Escherichia coli

J Biol Chem, 1976 Feb 25, 251(4), 975 - 81
On the fidelity of DNA replication . Enzyme activities associated with DNA polymerases from RNA tumor viruses; Seal G et al.; DNA polymerase from RNA tumor viruses ("reverse transcriptase") has been analyzed for activities which have been associated with other DNA polymerases . Homogeneous DNA polymerase from avian myeoblastosis virus catalyzes pyrophosphate exchange and pyrophosphorolysis . Pyrophosphate exchange is dependent on a template and is base-specific . With avian myeloblastosis virus DNA polymerase, ribonucleotide templates are more efficient for synthesis while deoxyribonucleotide templates are more effective for pyrophosphate exchange . Synthesis, pyrophosphate exchange, and pyrophosphorolysis were inhibited by the chelating agent 1,10-phenanthroline, suggesting that enzyme-bound zinc is required for each of these reactions . The pyrophosphate exchange reaction was also demonstrated with the DNA polymerase from a mutant of Rous sarcoma virus that possesses a temperature-sensitive DNA polymerase . The pyrophosphate exchange reaction with the mutant polymerase is temperature-sensitive which demonstrates that pyrophosphate exchange is indeed catalyzed by the viral DNA polymerase and that the same mutation effects both DNA polymerase and pyrophosphatase activity . Unlike Escherichia coli DNA polymerase I, the DNA polymerase from avian myeloblastosis virus fails to degrade polydeoxyribonucleotides or to convert deoxynucleoside triphosphates into monophosphates . This lack of hydrolytic activities in avian myeoblastosis DNA polymerase should facilitate kinetic studies on the mechanism of DNA synthesis by this enzyme.

J Biol Chem, 1976 Feb 25, 251(4), 962 - 7
Calcium transport driven by a proton gradient and inverted membrane vesicles of Escherichia coli; Tsuchiya T et al.; Calcium transport into inverted vesicles of Escherichia coli was observed to occur without an exogenous energy source when an artificial proton gradient was used . The orientation of the proton gradient was acid inside and alkaline outside . Either phosphate or oxalate was necessary for transport, as was found for respiratory-driven or ATP-driven uptake (Tsuchiya, T., and Rosen, B.P . (1975) J . Biol . Chem . 250, 7687-7692) . Phosphate accumulation was found to occur in conjunction with calcium accumulation . Calcium transport driven by an artificial proton gradient was stimulated by dicyclohexylcarbodiimide, an inhibitor of the Mg2+ATPase (EC 3.6.1.3) . Valinomycin, which catalyzes electrogenic potassium movement, stimulated calcium accumulation, while nigericin, which catalyzes electroneutral exchange of potassium and protons, inhibited both artificial proton gradient-driven transport and respiratory-driven transport . Other properties of the proton gradient-driven system and the previously reported energy-linked calcium transport system are similar, indicating that calcium is transported by the same carrier whether energy is supplied through an artificial proton gradient or an energized membrane state . These results suggest the existence of a calcium/proton antiport.

J Biol Chem, 1976 Feb 25, 251(4), 1207 - 16
31P NMR of phosphate and phosphonate complexes of metalloalkaline phosphatases; Chlebowski JF et al.; 31P NMR spectra of phosphate and phosphonate complexes of Escherichia coli alkaline phosphatase have been obtained by Fourier transform NMR methods . One equivalent of P1i, bound to Zn(II) alkaline phosphatase, pH 8, gives rise to a single 31P resonance 2 ppm downfield from that for Pi, and assignable to the noncovalent complex, E-P . Inorganic phosphate in excess of 1 eq per enzyme dimer gives rise to a resonance at the position expected for free Pi . At pH 5.1, a second resonance appears 8.5 ppm downfield from that for free Pi, and is assignable to the covalent complex, E-P . The large downfield shift suggests that the enzyme phosphoryl group is highly strained with an O-P-O bond angle of under 100 degrees.

J Biol Chem, 1976 Feb 25, 251(4), 1202 - 6
Metallophosphoryl and Apophosphoryl Alkaline Phosphatases; Chlebowski JF et al.; The noncovalent phosphate (E-P) and covalent phosphory (E-P) complexes of Zn(II), Cd(II), and apoalkaline phosphatases of Escherichia coli have been studied by stopped flow kinetic methods and 32P-labeling techniques . With 2,4-dinitrophenylphosphate as substrate, preincubation of the Zn(II) enzyme with Pi at pH 8 slows the pre-steady state burst rate, but does not affect the burst magnitude of 1 mol of ROH per enzyme dimer . Preincubation of the enzyme with Pi at pH 5.5 reduces the burst magnitude by one-half, as well as reducing the burst rate . Reduction of the burst magnitude as a function of the pH of the preincubation with Pi follows the same function as that previously established for the formation of E-P . Hence, ROP phosphorylates the enzyme by displacing phosphate from E-P during a pre-steady state reaction, while E-P turns over at the steady state velocity.

Biochemistry, 1976 Feb 24, 15(4), 818 - 23
Mechanism of aminoacylation of tRNA . Proof of the aminoacyl adenylate pathway for the isoleucyl- and tyrosyl-tRNA synthetases from Escherichia coli K12; Fersht AR et al.; The following observations show that the formation of isoleucyl-tRNA catalyzed by the isoleucyl-tRNA synthetase from Escherichia coli K12 involves the initial rapid formation of an isoleucyl adenylate complex followed by the slow, rate-determining, transfer of the isoleucyl moiety to tRNA . (1) The rate constant for the transfer of {14C}Ile from the E-{14C}Ile approximately AMP complex to tRNA is the same as the turnover number for the steady-state isoleucylation of tRNA at pH 7.78 (1.5 s-1) and pH 5.87 (0.34 s-1) . (2) On mixing a solution of isoleucyl-tRNA synthetase and tRNA with {14C}Ile and ATP the steady-state rate of isoleucylation is attained in the first turnover of the enzyme, with little or no "burst" or charging that would indicate a slow step after the transfer step . (3) The pyrophosphate exchange reaction in the presence of tRNA is 40 times faster than the overall rate of isoleucylation of tRNA . (4) Similarly, rapid quenching experiments indicate that isoleucyl adenylate is formed prior to the transfer step . The possibility that isoleucyl adenylate formation is a parallel reaction caused by a second active site on the enzyme is ruled out both by the stoichiometry in this rapid quenching experiment and also the overall stoichiometry of isoleucyl-tRNA formation . At saturating reagent concentrations the major species in solution is the E-tRNA-Ile approximately AMP complex . Similar observations are found for the tyrosyl-tRNA systhetase except that at saturating reagent concentrations the rate constants for both tyrosyl adenylate formation and transfer are similar so that both processes contribute to the rate-determining step.

Biochemistry, 1976 Feb 24, 15(4), 804 - 11
The role of 16S rRNA in ribosomal binding of IF-3; Pon CL et al.; The binding of initiation factor IF-3 to Escherichia coli 30S ribosomal subunits has been found to be inhibited by rRNA ligands such as ethidium bromide, polyamines, and monovalent alkali metals . The order of effectiveness of the polyamines (spermine greater than spermidine greater than putrescine) and alkali metals (Li+ greater than Na+ greater than K+) in inhibiting the ribosomal binding of IF-3 parallels their degree of affinity for the RNA . Furthermore, the binding of IF-3 to 30S subunits chemically modified by photooxidation with rose bengal, nitration with tetranitromethane, and reaction with kethoxal, monoperphthalic acid, and p-chloromercuribenzoic acid was studied . Results obtained after the direct treatment of the 30S subunits with the above chemical reagents or upon reconstitution of 30S particles having a modified rRNA or ribosomal proteins indicate that the IF-3 binding site is preferentially lost when the rRNA becomes modified . It was found that IF-3 could bind normally to 30S subunits lacking protein S1 or proteins S11, S12, S19, and S21 (and perhaps S14) which had been cross-linked to IF-3 in other laboratories.

Biochemistry, 1976 Feb 24, 15(4), 734 - 40
Synchronous digestion of SV40 DNA by exonuclease III; Wu R et al.; We have established an optimal condition for the synchronous digestion of SV40 DNA with Escherichia coli exonuclease III . Electron microscopy and polyacrylamide gel electrophoresis were used to obtain accurate measurements on the lengths of DNA before and after exonuclease III digestion . Based on this finding, a new method for determining the sequence of long duplex DNA can be realized . It involves (a) the synchronous digestion of the DNA from the 3' ends with exonuclease III, followed by (b) repair synthesis with labeled nucleotides and DNA polymerase, and (c) sequence analysis of the repaired DNA.

Eur J Biochem, 1976 Feb 16, 62(2), 313 - 22
Molecular-weight determination of animal-cell RNA by electrophoresis in formamide under fully denaturing conditions on exponential polyacrylamide gels; Spohr G et al.; A method for electrophoretic analysis of RNA under fully denaturing conditions on exponential gradient polyacrylamide gels is described . Full denaturation, and strand separation of DNA - RNA hybrids and double-stranded RNA is obtained in dry formamide only if electrophoresis is carried out at 45 degrees and 55 degrees C, respectively . In such conditions, the effects of secondary structure of RNA, important in aqueous medium, are suppressed and a linear correlation is obtained between the logarithm of the molecular weight of an RNA and its final position in the gel over the entire molecular weight range of 10(4) - 10(7) . Based on absolute molecular weight standards, obtained from sequenced rRNA of Escherichia coli and tRNA and extrapolating to higher molecular weights the size of animal cell was reexamined . Precursor tRNA from HeLa cells migrates according to a molecular weight of 4.1 x 10(6) . Nascent precursor mRNA has molecular weights of up to 5 x 10(6) in the case of duck erythroblasts and of up to 10(7) in HeLa cells . This seems to represent the largest size of non-viral animal-cell RNA molecules.

Eur J Biochem, 1976 Feb 16, 62(2), 285 - 92
Enzyme-linked immunoassay . Conjugation of rabbit anti-(human immunoglobulin G) antibody with beta-D-galactosidase from Escherichia coli and its use for human immunoglobulin G assay; Kato K et al.; Rabbit immunoglobulin G (IgG) was reduced by incubating with 10 mM 2-mercaptoethylamine and then treated with excess amounts of N,N'-o-phenylenedimaleimide . As a result, maleimide residues were introduced into rabbit IgG molecules . Rabbit IgG containing maleimide residues could be coupled to beta-D-galactosidase from Escherichia coli which has sulfhydryl groups in the molecule . The resulting rabbit IgG (antibody)-enzyme complex may be useful for immunoassay of antigens . As an example, human IgG was assayed by the sandwich method using the rabbit anti-(human IgG) IgG-beta-D-galactosidase complex and amounts of human IgG as small as 3 fmoles were measurable.

Biochem J, 1976 Feb 15, 154(2), 311 - 8
An unusual precursor of 50S ribosomes in a mutant of Escherichia coli; Markey F et al.; Escherichia coli strain 15-28 is a mutant with a defect in ribosome synthesis that leads to the accumulation of large amounts of ribonucleoprotein ("47S") particles during exponential growth . These particles are precursors to 50S ribosomes, but are distinct from precursors detected by pulse-labelling of the parent strain and also from ribosome precursors that accumulate during inhibition of growth by CoC12 . Either ribosome assembly in the mutant differs from that in the wild-type strain, or 47S particles represent a hitherto unstudied stage in the synthesis of 50S ribosomes.

J Am Vet Med Assoc, 1976 Feb 15, 168(4), 317 - 8
Use of a formalin-treated, live Escherichia coli vaccine in the prevention of neonatal enteric colibacillosis in swine; Ward GE et al.; A field trial was conducted to evaluate the effectiveness of an Escherichia coli vaccine in prevention of neonatal enteric colibacillosis in swine . Sows (272 total) were allotted to control (151 sows) and vaccinated groups (121 sows) . Sows in the vaccinated groups were given a single intramuscular injection of a formalin-treated, live E coli vaccine 10 to 20 days prior to farrowing . The effects of the vaccination were to: (1) reduce mortality from 2.14 to 0.93 (P less than 0.001) pigs per litter; (2) reduce number of pigs with diarrhea, from 7.28 to 3.12 (P less than 0.004) per litter; and (3) increase number of pigs weaned, from 7.62 to 8.2 (P less than 0.005) per litter . The advantages of vaccination were most apparent in the barns with less than adequate sanitation and ventilation.

Biochem J, 1976 Feb 15, 154(2), 285 - 94
Kinetic characterization of the membrane-bound cytochromes of Escherichia coli grown under a variety of conditions by using a stopped-flow dual-wavelength spectrophotometer; Haddock BA et al.; A study was made of the rapid oxidation kinetics of the cytochromes of Escherichia coli . The b-type cytochromes were kinetically heterogeneous, with one species (presumably cytochrome o) oxidized so rapidly that it could fully support observed oxidation rates . Cytochrome d but not cytochrome a1 was also kinetically competent to support respiration . However, in cells grown anaerobically in the presence of NO3-, cytochrome d exhibited slow oxidation kinetics and a red-shift in its reduced-minus-oxidized difference spectrum.

Biochim Biophys Acta, 1976 Feb 13, 422(2), 302 - 8
Conformations of lysine-sensitive aspartokinase; Shaw JF et al.; 1 . The technique of differential thermal and proteolytic inactivation has been employed as a conformational probe for the lysine-sensitive aspartokinase (EC 2.7.2.4) of Escherichia coli B . 2 . L-Amino acid inhibitors of this enzyme each induce a characteristic enzyme conformation . This is evidenced by rates of thermal and proteolytic inactivation and Arrhenius activation energies for thermal inactivation which are characteristic of the amino acid present . 3 . Phenylalanine and leucine binding are mutually exclusive as evidenced by competitive behavior in thermal inactivation experiments, suggesting a hydrophobic amino acid binding site with broad specificity . 4 . The phenylalanine-dependent conformation and the leucine-dependent conformation differ considerably . In comparison with the native enzyme, the former is more labile to proteolysis by trypsin whereas the latter is more stable . First-order rate constants for thermal inactivation of the phenylalanine- and leucine-dependent conformations are, respectively, about one-half and one-tenth that of the native enzyme . 5 . Items 3 and 4 taken together suggest that the conformations are ligand induced and do not arise via ligand stabilization of spontaneously arising conformers.

J Bacteriol, 1976 Feb, 125(2), 518 - 23
Selection and properties of Escherichia coli mutants defective in the synthesis of cyclopropane fatty acids; Taylor F et al.; Mutants of Escherichia coli K-12 defective in the synthesis of cyclopropane fatty acids (CFA) have been selected and isolated by a L-{methyl-3H}methionine suicide procedure . Two mutants were isolated . Stationary-phase cultures of both mutants contain less than 0.7% of the CFA content found in the parental strain . The CFA deficiency is attributed to a deficiency of CFA synthetase activity . Extracts of both mutants contain less than 10% of the CFA synthetase activity found in extracts of the parental strain . Experiments in which parental and mutant extracts were mixed indicate that the lack of activity in the mutant strains is not due to an inhibitor of CFA synthetase present in the mutant extracts . We have not yet detected a physiological phenotype for these mutants . These strains grow normally at various temperatures in a variety of media . We have tested survival (colony-forming ability) in response to (i) prolonged incubation in stationary phase, (ii) exposure to drying, and (iii) exposure to detergents, heavy metals, low pH, high salt concentration, and a variety of other environmental conditions . The survival of both mutants is identical to that of the parental strain under all conditions tested . The compositions (excepting the CFA deficiency) and metabolic turnover rates of the phospholipids of both mutant strains are indistinguishable from those of the wild-type strain . The transport of several amino acids also seems normal in these mutants.

Biochemistry, 1976 Feb 10, 15(3), 593 - 9
Changes in the expression of the chloroplast genome of Euglena gracilis during chloroplast development; Chelm BK et al.; The transcription program from the chloroplast genome of Euglena gracilis Z during light-induced chloroplast development has been characterized by hybridization of total cell RNA to 3H-labeled chloroplast DNA . Pancreatic DNase activated, purified Euglena chloroplast DNA was enzymatically labeled by Escherichia coli DNA polymerase I with {3H}TTP as a substrate . The {3H}DNA 'hybridization probe" was characterized by the kinetics of its renaturation with purified chloroplast DNA, and the thermal stability of {3H}DNA-DNA, and {3H}DNA-RNA hybrids . The {3H}DNA was hybridized in trace amounts to total cellular RNA extracted from Euglena cells 0, 4, 8, 12, 24, 48, and 72 h after the onset of chloroplast development . A large percentage (17%) of the chloroplast genome was found to be transcribed in dark adapted cells . Development is marked by an initial decrease in the fraction of the genome transcribed followed by an increase to 23% transcribed at the end of 72 h of light growth . Chloroplast RNA transcripts were also characterized by the kinetics of their hybridization to chloroplast DNA . The chloroplast specific RNA population is composed of three abundance classes, and the R0t1/2 for each class varies during the early stages of chloroplast development.

Biochemistry, 1976 Feb 10, 15(3), 666 - 71
Behavior of colicins E1, E2, and E3 attached to sephadex beads; Lau C et al.; Colicins E1, E2, and E3 were covalently attached to Sephadex G-25 beads by cyanogen bromide activation . These immobilized colicins were still active in binding to specific receptors on sensitive and tolerant cells but not to resistant cells which lack such receptors . Bound colicin E3 also retained its ability to inhibit protein synthesis in vitro . Leakage of free colicin from these coated beads was negligible . Assays sensitive to free colicin activity of 1 part in 10(7) of the bound toxin failed to detect any soluble activity . The viability of different cell types bound specifically onto these colicin-Sephadex beads was assayed by using autoradiography based on labeled amino acid uptake . Immobilized E1 killed 90% of bound sensitive cells while less than 10% of sensitive cells bound to E2 and E3 were killed in this assay . These observations agree very well with previously suggested mechanisms which propose that E1, whose target site appears to be at the membrane level, can kill sensitive cells by binding to the cell surface, but that for E2 and E3 penetration of part or all of the molecule is necessary for killing action to be observed.

Biochemistry, 1976 Feb 10, 15(3), 569 - 75
Nepsilon-acetyllysine transfer ribonucleic acid: a biologically active analogue of aminoacyl transfer ribonucleic acids; Johnson AE et al.; Unfractionated Escherichia coli tRNA has been aminoacylated with lysine and preferentially acetylated at the epsilon-amino nitrogen of lysine by reaction with N-acetoxysuccinimide . After treatment with peptidyl-tRNA hydrolase, 90% of the aminoacylated tRNA molecules were Nepsilon-acetyl-Lys-tRNA . Post-ribosomal supernatant enzymes would not deacylate Nepsilon-acetyl-Lys-tRNA in the presence of AMP and PPi, even though such mixed enzymes could acylate, with lysine, tRNA which had been exposed to the acetylation reaction conditions . Poly(rA) stimulated the binding of Nepsilon-acetyl-Lys-tRNA to E . coli ribosomes . At the ribosome and tRNA concentrations used, Nepsilon-acetyl-Lys-tRNA was bound nearly as well as Lys-tRNA at 30 mM Mg2+; at 10 mM Mg2+, the analogue was bound one-half as well as Lys-tRNA . Both Lys-tRNA and Nepsilon-acetyl-Lys-tRNA reacted only slightly with puromycin at either 10 or 30 mM Mg2+ . When Lys-tRNAE . coli or Nepsilon-acetyl-Lys-tRNAE . coli were added to rabbit reticulocyte cell-free protein synthesizing incubations, the incorporation of either amino acid into protein was complete within 5 min . The final incorporation level of the analogue was 82% that of the unmodified lysine . After protein synthesized in the presence of Nepsilon-acetyl-{14C}Lys-tRNA had been digested enzymatically to single amino acids, ion-exchange chromatography and paper electrophoresis showed that nearly all of the radioactivity was present as Nepsilon-acetyllysine . Gel filtration of the post-ribosomal supernatant revealed that most of the Nepsilon-acetyllysine radioactivity cochromatographed with tetrameric hemoglobin.

Biochemistry, 1976 Feb 10, 15(3), 536 - 43
Manganese(II) and substrate interaction with unadenylylated glutamine synthetase (Escherichia coli w) . I . Temperature and frequency dependent nuclear magnetic resonance studies; Villafranca JJ et al.; A comprehensive study of solvent interaction with unadenylylated glutamine synthetase (E1.7) has been conducted using the enzyme isolated from Escherichia coli W . The longitudinal, (1/T1p)b, and transverse, (1/T2p)b, proton relaxation rates were measured with various enzyme samples as a function of frequency (6-48 MHZ) and temperature (1-40 degrees C) . With Mn(II) bound at the "tight" metal ion site approximately two water molecules are rapidly exchanging with bulk solvent . This number is reduced to approximately one in the presence of glutamine . All data were successfully analyzed according to the Solomon-Bloembergen-Morgan (SBM) scheme for dipolar relaxation of water protons interacting with enzyme-bound Mn(II) . The correlation time for this process varies from 1 to 3 X 10(-9) for the complexes described above . Significant contributions to the correlation time arise from both 1/taum, the exchange rate for water molecules bound at the metal site, and from 1/taus, the electron spin relaxation rate for Mn(II) with the latter rate showing a frequency dependence at the magnetic field strengths used in this study . A study of Mn(II) binding to E1.7 at 25 degrees C revealed two classes of metal ion sites, a "tight" set of one per subunit with KD=5.0 X 10(-7) M and a "weak" set of one per subunit with KD=4.5 X10(-5)M . In the presence of glutamine the affinity of the first site for Mn(II) was unchanged but the KD value for the weak site changed to 3 X 10(-6)M . In E1.7 samples with Mn(II) bound at both the tight and weak metal ion sites the data are interpretable with two rapidly exchanging water molecules interacting with each bound Mn(II)ion . With saturating amounts of glutamine or of ADP or of glutamine plus ADP plus arsenate, the proton relaxation rates progressively decreased suggesting that the substrates or inhibitors used were interacting with the bound Mn(II) ions resulting in diminished solvent accessibility to these bound ions . These results are interpretable in terms of ligand substitution into the coordination sphere of the bound Mn(II) ions . Indeed this is probably the case for Mn(II) at the weak metal ion site since Hunt et al . ((1975), Arch . Biochem . Biophys . 166, 102) showed that Mn(II) can bind as the Mn(II)-ADP complex to the second metal ion site . Results of proton relaxation rate data on E1.7 with Mn(II) bound at both the tight and weak metal ion sites led to the conclusion that these metal ion sites are greater than 6 A apart . In comparison with proton relaxation rate data on fully adenylylated glutamine synthetase (E11.8) as studied by Villafranca and Wedler ((1974), Biochemistry 13, 3286), the first "tight" metal ion site in E11.8 has three rapidly exchanging water molecules . Mn(II) has a weaker binding constant to E11.8 (KD approximately 5 X 10(-6)M) at the pH value used in both studies and a suggestion is made that an additional protein ligand is binding to Mn(II) in glutamine synthetase when the subunits are not adenylylated.

J Biol Chem, 1976 Feb 10, 251(3), 898 - 901
Syntheses of elongation factors Tu and G are under stringent control in Escherichia coli; Furano AV et al.; We have compared the synthesis of the elongation factors Tu and G at 30 and 36.5 degrees in three strains of Escherichia coli: NF314 (rel+valS+), NF536 (rel+valSts), and NF537 (rel-valSts) . At the elevated temperature, the latter two strains continue to grow but suffer a partial deprivation of valyl-tRNA . As a consequence, the syntheses of stable RNA, Tu, and G are decreased in NF536; the syntheses of stable RNA, Tu, and G are increased in NF537 . These results indicate that the syntheses of Tu and G are directly or indirectly under the influence of the rel gene.

J Biol Chem, 1976 Feb 10, 251(3), 883 - 92
Regulation of carbohydrate uptake and adenylate cyclase activity mediated by the enzymes II of the phosphoenolpyruvate: sugar phosphotransferase system in Escherichia coli; Saier MH Jr et al.; The uptake of various carbohydrates and the synthesis of adenosine 3':5'-monophosphate (cyclic AMP) are subject to inhibition by sugar substrates of the phosphoenolpyruvate:sugar phosphotransferase system in Escherichia coli . The induced synthesis of the sugar-specific components of the phosphotransferase system was studied and correlated with the induction of regulatory interactions controlling glycerol uptake and net cyclic AMP synthesis . Activities of the Enzyme II complexes specific for glucose, fructose, and mannitol were measured both in vivo and in vitro . These activities were induced 8- to 40-fold by growth in the presence of the appropriate substrate-inducers . Cross inducer specificities were noted . Maximal inhibition of glycerol uptake and cyclic AMP synthesis by a sugar substrate of the phosphotransferase system required induction of the Enzyme II complex specific for that sugar and was abolished by mutations which destroyed Enzyme II activity . The inducer specificities of the regulatory systems and of the Enzymes II were found to be the same . A mutation which depressed the cellular activity of Enzyme I of the phosphotransferase system did not relieve sensitivity to inhibition . The results suggest that adenylate cyclase and several carbohydrate permeases are subject to coordinate regulation by a mechanism which depends on the catalytic activities of the protein components of the phosphotransferase system.

J Biol Chem, 1976 Feb 10, 251(3), 651 - 7
Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from Escherichia coli . 9 . Enzymatic joining of chemically synthesized deoxyribopolynucleotide segments corresponding to nucleotide sequence 57-94; Panet A et al.; The DNA duplexes representing nucleotide sequences 61-89 and 57-94 have been synthesized, isolated pure, and fully characterized . Synthesis of the duplex with the nucleotide sequence 61-89 involved the DNA ligase-catalyzed joining of chemically synthesized deoxyoligonucleotide segments 14 to 18 shown in Fig . 1A, while for the longer duplex (sequences 57-94) seven deoxyribooligonucleotides (segments 13 to 19, Fig . 1B) were used in one-step enzymatic joining . The joining of the short tetranucleotide (segment 16) to the segment 17 required the presence of the adjacent segment 14, even if the latter did not contain a 5'-phosphate group, to allow its joining to segment 16 . However, in the synthesis of both of the DNA duplexes, the yields were comparatively low (30 to 40%) and could not be significantly increased although a variety of conditions was tried . The main cause in both cases evidently was the sluggish joining of segment 14 to 16 and of segment 16 to segment 17 . Although the original plan for the total synthesis of this part of the gene for the tRNA precursor involved the DNA duplex consisting of segments 14 to 18, this duplex could not be quantitatively phosphorylated at the two 5'-OH ends for subsequent joining to the adjoining parts of the gene . The DNA duplex consisting of segments 13 to 19, which possesses both terminal 5'-OH groups at protruding single-stranded ends, was readily phosphorylated and used successfully in the total synthesis of the gene as described in an accompanying paper.

J Biol Chem, 1976 Feb 10, 251(3), 642 - 59
Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from Escherichia coli . 8 . Enzymatic joining of the chemically synthesized segments to form DNA duplexes corresponding to nucleotide sequences 23-60 and 23-66; Loewen PC et al.; Polynucleotide ligase-catalyzed joining of the eight chemically synthesized deoxyribopolynucleotide segments (Fig . 1) comprising the nucleotide sequence 23-66 of the DNA corresponding to the Escherichia coli tyrosine tRNA precursor has been systematically investigated . Joining was studied using all possible combinations of 3, 4, and 5 and larger numbers of segments at a time . The extent of joining varied widely (0 to about 90%) in three component systems . The "self-structure" of some of the components evidently inhibited the joining . Addition of a fourth segment in general enhanced the extent of joining and optimal yields were obtained in systems containing six or more segments . A comparison of the T4-induced ligase and the E . coli polynucleotide ligase for joining of the chemically synthesized segments showed the E . coli enzyme to be inferior to the T4-induced ligase . Satisfactory syntheses of the duplexes {IIa} and {IIb} comprising, respectively, eight and seven segments were achieved in single steps . Of the two terminal segments carrying 5'-OH groups in the duplexes, only one (segment 7) was used in the prephosphorylated form . The duplexes were isolated pure and characterized by enzymatic degradations and by electrophoresis.

J Biol Chem, 1976 Feb 10, 251(3), 634 - 41
Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from Escherichia coli . 7 . Enzymatic joining of the chemically synthesized segments to form a DNA duplex corresponding to the nucleotide sequence 1-26; Sekiya T et al.; Duplex {I}, which represents the nucleotide sequence 1-26 of the double-stranded DNA corresponding to the precursor for a tyrosine suppressor tRNA, has been synthesized by the enzymatic joining of five chemically synthesized deoxyribooligonucleotide segments . The synthesis was accomplished in two different ways . In a one-step synthesis, all of the five segments were used together: segments 2, 3, and 5 carried 5'-33P-labeled phosphate groups while segment 4 carried a 32P-phosphate group . An alternative, two-step method involved the joining of 5'-32P-phosphorylated segment 2 to segment 4 (carrying 5'-OH group or 5'-32P- or 33P-labeled phosphate group) in the presence of segment 3 followed by the joining of {5-32P}segment 5 in a second step . The duplex {I}' (segments 2 to 5) thus obtained was phosphorlated at the 5'-ends with polynucleotide kinase and then joined to segment 1 to give duplex {I} quantitatively . The preparative methods described have the desired flexibility for performing the subsequent operations necessary for the total synthesis of the structural gene for the tyrosine suppressor tRNA precursor.

J Biol Chem, 1976 Feb 10, 251(3), 624 - 33
Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from Escherichia coli . 6 . Synthesis of the deoxyribopolynucleotide segments corresponding to the nucleotide sequence 100-126; Agarwal KL et al.; Chemical syntheses of the tridecanucleotide, d(G-C-T-T-C-C-C-G-A-T-A-A-G), the dodecanucleotide, d(G-C-T-C-C-C-T-T-A-T-C-G), the decanucleotide, d(G-G-A-G-C-A-G-G-C-C), the nonanucleotide, d(T-A-C-T-G-G-C-C-T), and the hexanucleotide, d(G-G-A-A-G-C), are described . Together, these syntheses represent the nucleotide sequence 100-126 of the DNA corresponding to the Escherichia coli tyrosine tRNA precursor . The synthesis of the dodecanucleotide d(G-C-T-C-C-C-T-T-A-T-C-G), was accomplished by the condensation of the previously described protected nonanucleotide, d{(MeOTr)ibG-anC-T-anC-anC-anC-T-T-bzA}, with the trinucleotide block d{pT-anC-mbG(Ac)} . Synthesis of the other segments involved stepwise condensations to the 3'-OH group of growing oligonucleotide chains, starting with suitably protected deoxyribonucleosides and using protected mono-, di-, and trinucleotides as the incoming blocks . The final products, after deprotection, were purified by anion exchange chromatography and characterized . The synthesis of this part of the DNA was planned so that only a hexanucleotide segment is used to go up to the 3'-end (nucleotide 126) of the DNA and, therefore, it is amenable to elongation by chemical methods when the nucleotide sequence of the several nucleotides beyond this end becomes known.

J Biol Chem, 1976 Feb 10, 251(3), 609 - 23
Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from Escherichia coli . 5 . Synthesis of the deoxyribopolynucleotide segments representing the nucleotide sequence 71-103; Jay E et al.; Chemical syntheses of the pentadecanucleotide, d(G-G-T-G-G-G-G-T-T-C-C-C-G-A-G), the undecanucleotides, d(G-G-T-G-G-G-G-T-T-C-C) and d(C-C-C-C-A-C-C-A-C-G-G), the decanucleotide, d(G-T-A-A-T-G-C-T-T-T), and the nonanucleotides, d(A-T-T-A-C-C-C-G-T) and d(A-G-T-A-A-A-A-G-C) are described . The deoxyribopolynucleotides together represent the DNA duplex corresponding to the nucleotide sequence 71-103 (from the 3'-end) of the gene for the tyrosine suppressor tRNA . Synthesis of the guanine-rich undecanucleotide d(G-G-T-G-G-G-G-T-T-C-C) was performed by the use of a new protecting group for the guanine ring, the methylbutyryl group . The heptanucleotide d{(MeOTr)mbG-mbG-T-mbG-mbG-mbG-mbG}, prepared by the new method, was condensed with the tetranucleotide d{panC-anC-T-T(Ac)} . All of the condensations described followed previously developed chemical principles and started with the N- and 5'-protected deoxyribonucleosides . Successive condensations at the 3'-end with protected mononucleotides, preformed di-, tri-, or tetranucleotides gave products which were separated by anion exchange chromatography and characterized by chemical and enzymatic methods.

J Biol Chem, 1976 Feb 10, 251(3), 599 - 608
Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from Escherichia coli . 4 . Synthesis of deoxyribopolynucleotide segments corresponding to the nucleotide sequence 47-78; Agarwal KL et al.; The chemical syntheses of the dodecanucleotide, d(G-C-C-G-C-T-C-G-G-G-A-A), the decanucleotides, d(T-T-T-A-G-A-G-T-C-T), d(G-C-T-C-C-C-T-T-T-G), d(C-G-G-C-C-A-A-A-G-G), and the nonanucleotide, d(G-A-G-C-A-G-A-C-T), are described . The deoxypolynucleotides together represent the DNA duplex corresponding to the nucleotide sequence 47-78 of the gene for the tyrosine suppressor tRNA . Chemical syntheses used protected mono- and oligonucleotides and stepwise condensation methods . The detailed plans used are given in Diagrams 1 to 4 in the text . Two additional notable features in the present syntheses were: (a) solvent extraction procedures for the preparation of oligonucleotides as large as pentanucleotides and (b) the demonstration that a heptanucleotide containing 5'-phosphate group can be used successfully in condensation with the 3'-OH group of another oligonucleotide . The synthetic polynucleotides were purified and characterized at protected and unprotected levels.

J Biol Chem, 1976 Feb 10, 251(3), 571 - 86
Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from Escherichia coli . 2 . Chemical synthesis of the deoxypolynucleotide segments corresponding to the nucleotide sequence 1-31; van de Sande JH et al.; Chemical synthesis of the undecanucleotides d(T-G-G-G-G-G-A-A-G-G-A), d(C-C-C-C-A-C-C-A-C-C-A), and d(T-C-G-A-A-T-C-C-T-T-C), and the nonanucleotides, d(T-T-C-G-A-A-C-C-T) and d(T-T-C-G-A-A-G-G-T) are described . The deoxyribopolynucleotides together represent the DNA duplex corresponding to the nucleotide sequence 1-31 (from the 3'-end) of the gene for the tyrosine suppressor tRNA . The synthesis, which basically used the previously developed chemical methods, started with 5' and N-protected deoxyribonucleosides . Successive condensations at the 3'-end were performed using suitably protected mononucleotides or preformed di- and trinucleotides . The condensing agents used were mesitylenesulfonyl chloride or triisopropyl benzenesulfonyl chloride . The required condensation products were isolated partly by solvent partition methods or, in the case of longer chains, by anion exchange chromatography . The completely deprotected deoxypolynucleotides were further purified by anion exchange chromatography in the presence of 7 M urea and characterized by chemical and enzymatic methods.

J Biol Chem, 1976 Feb 10, 251(3), 565 - 70
Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from Escherichia coli . 1 . General introduction; Khorana HG et al.; With the ultimate objective of the total synthesis of a tRNA gene including its transcriptional signals, an Escherichia coli tyrosine suppressor tRNA gene was chosen . The arguments in favor of this choice are presented . A plan for the total synthesis of the 126-nucleotide-long DNA duplex corresponding to a precursor (Altman S., and Smith, J . D . (1971) Nature New Biol . 233, 35) to the above tRNA is formulated . The plan involves: (a) the chemical synthesis of 26 deoxyribooligonucleotide segments, (b) polynucleotide ligase-catalyzed joining of several segments at a time to form a total of four DNA duplexes with appropriate comlementary single-stranded ends, and (c) the joining of the duplexes to form the entire DNA duplex . Ten accompanying papers describe the experimental realization of this objective.

Biochemistry, 1976 Feb 10, 15(3), 487 - 93
Isolation of viral specific RNA from SV40 infected cells by viral DNA chemically linked to a cellulose matrix; Shih TY et al.; SV40 DNA fragments chemically attached to neutral cellulose powder with a water-soluble carbodiimide have been used to isolate late lytic viral specific RNA from virus infected cells . Exhaustive hybridization to SV40 DNA reveals that virtually all of the isolated RNA molecules contain SV40 specific sequences . Comparison with SV40 cRNA prepared with purified Escherichia coli RNA polymerase and a SV40 DNA I template suggests that the purity of the isolated SV40 specific RNA is very close to 100% . The background level for the nonspecific binding of RNA to a purified cellulose matrix is very low . Retention of nonspecific RNA by SV40 DNA-cellulose is only 1.5% of the viral specific RNA isolated under saturating conditions for the column . Sedimentation in neutral sucrose suggests that the major 16S viral specific RNA has been isolated largely intact.

J Biol Chem, 1976 Feb 10, 251(3), 676 - 94
Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from Escherichia coli . 12 . Synthesis of a DNA duplex corresponding to a sequence of 23 nucleotide units adjoining the C-C-A end; Ramamoorthy et al.; In continuing the work on the total synthesis of the gene for an Escherichia coli tyrosine suppressor tRNA (accompanying papers) and as a part of a study of the mechanism of transcription of this gene, a 23-nucleotide unit-long DNA corresponding to the previously determined (Loewen, P., Sekiya, T., and Khorana, H . G . (1974) J . Biol . Chem . 249, 217) sequence has been synthesized . The synthesis was carried out by dividing the total duplex into the following five deoxyribooligonucleotide segments, all of which were chemically synthesized: (a) the undecanucleotide, d(A-G-T-G-A-T-G-G-T-G-G); (b)the undecanucleotide, d(T-C-A-C-T-T-T-C-A-A-A); (c) the undecanucleotide, d(G-G-A-C-T-T-T-T-G-A-A); (d) the dodecanucleotide, d(A-G-T-C-C-C-T-G-A-A-C-T); and (e) the heptanucleotide, d(A-G-T-T-C-A-G) . All the five synthetic oligonucleotides were characterized by chromatographic and radioactive fingerprinting methods after labeling the 5'-ends with a 32P-phosphate group . Synthesis of the double-stranded DNA duplex was completed by joining 5'-phosphorylated segments 1, 3, and 4 in the presence of segments 2 and 5 using T4-polynucleotide ligase . The DNA duplex was characterized.

J Biol Chem, 1976 Feb 10, 251(3), 667 - 75
Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from Escherichia coli . 11 . Enzymatic joining to form the total DNA duplex; Kleppe R et al.; The DNA duplex corresponding to the entire length (126 nucleotides) of the precursor for an Escherichia coli tyrosine tRNA has been synthesized . Duplex {I} (Sekiya, T., Besmer, P., Takeya, T., and Khorana, H . G.(1976) J . Biol . Chem . 251, 634-641), corresponding to the nucleotide sequence 1-26, containing single-stranded ends and carrying one appropriately labeled 5'-phosphate group, was joined to duplex {II} (Loewen, P . C., Miller, R . C., Panet, A., Sekiya, T., and Khorana, H . G . (1976) J . Biol . Chem . 251, 642-650) (nucleotide sequence 23-66 or 23-60) was phosphorylated with {gamma-33P}ATP at the 5'-OH ends . Duplex {III} (Panet, A., Kleppe, R., Kleppe, K., and Khorana, H . G . (1976) J . Biol . Chem . 251, 651-657) (nucleotide sequence 57-94 (Fig . 2)) was also phosphorylated at 5'-ends with {gamma-33P}ATP and was joined to duplex {IV} (Caruthers, M . H., Kleppe, R., Kleppe, K., and Khorana, H . G . (1976) J . Biol . Chem . 251, 658-666) (nucleotide sequence 90-126) which carried a 33P-labeled phosphate group on nucleotide 90 . The joined product, duplex {III + IV} (nucleotide sequence 57-126) was characterized . The latter duplex was joined to the duplex {I + II} to give the total duplex . The latter contains singlestranded ends (nucleotides 1 to 6 and 121 to 126) which can either be "filled in" to produce the completely base-paired duplex or may be used to add the promoter and terminator regions at the appropriate ends.

J Biol Chem, 1976 Feb 10, 251(3), 658 - 66
Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from Escherichia coli . 10 . Enzymatic joining of chemically synthesized segments to form the DNA duplex corresponding to the nucleotide sequence 86-126; Caruthers MH et al.; The polynucleotide ligase-catalyzed joining of the eight chemically synthesized deoxypolynucleotides (segments 19 to 26), comprising the nucleotide sequence 86-126 of the DNA corresponding to the Escherichia coli tyrosine tRNA precursor has been investigated . Joining was studied using various combinations of 3, 4, or larger number of segments at a time . The extent of joining was in general low (0 to 40%) for the three-component as well as for the four-component systems . Joining of the five- and six- component systems was more satisfactory with yields from 25 to about 60% . The three duplexes {IVa} to {IVc}were prepared in single step reactions in yields of about 50% and were characterized . Duplex {IVd} could not be prepared in a single step reaction because of the failure of 5'-phosphorylated segment 26 to join to the rest of the duplex . Using a carefully annealed mixture of segments 24, 25, and phosphorylated segment 26, the joining of the latter to segment 24 could be realized in about 25% yield, much activated intermediate being concurrently present.

J Biol Chem, 1976 Feb 10, 251(3), 587 - 98
Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from Escherichia coli . 3 . Synthesis of deoxyribopolynucleotide segments corresponding to the nucleotide sequence 27-51; Minamoto K et al.; Chemical syntheses of the four deoxyribodecanucleotides, d(T-C-G-A-A-G-T-C-G-A), d(C-G-T-C-A-T-C-G-A-C), d(T-G-A-C-G-G-C-A-G-A), and d(C-T-A-A-A-T-C-T-G-C) are described . These polynucleotides form, respectively, segments 7 to 10 in the plan adopted for the total synthesis of the DNA corresponding to the precursor for the Escherichia coli tyrosine tRNA . The syntheses used the principles of stepwise addition of protected mono- and oligonucleotides to the 3'-hydroxyl end of growing oligonucleotide chains . Detailed schemes used in the present syntheses are shown in Diagrams 1 to 4 in the text . The final products were subjected to extensive chromatography and were characterized as pure by chemical and enzymatic procedures.

J Biol Chem, 1976 Feb 10, 251(3), 808 - 12
Purification and characterization of a DNA-dependent ATPase from Escherichia coli; Richet E et al.; A DNA-dependent ATPase has been isolated and purified from an Escherichia coli cell-free extract . The ATPase has the following characteristics: preferential dependence on single-stranded DNA, specificity for ATP hydrolysis, Km value of 1.4 X 10-4 M for ATP, and molecular weight of approximately 69,000 . The ATPase can be shown to bind to single stranded DNA . The resemblance between this ATPase and that isolated from vaccinia cores is discussed.

Biochemistry, 1976 Feb 10, 15(3), 544 - 53
Manganese (II) and substrate interaction with unadenylylated glutamine synthetase (Escherichia coli w) . II . Electron paramagnetic resonance and nuclear magnetic resonance studies of enzyme-bound manganese(II) with substrates and a potential transition-state analogue, methionine sulfoximine; Villafranca JJ et al.; The enhancement of the longitudinal proton relaxation rate of solvent water protons which occurs when Mn(II) is bound to the "tight" metal ion site of unadenylylated glutamine synthetase (GS) was used to determine the binding constant of L-methionine (SR)-sulfoximine to GS-Mn(II) complexes . The binary enhancement for GS-Mn(II) is 22 at 24 MHz, 25 degrees C . The enhancement is lowered in the presence of the sulfoximine and the computed dissociation constant is 30 muM with epsilont, the enhancement for the ternary complex, equal to 3.0 . Titration curves for the sulfoximine were also obtained in the presence of Mg-ADP, Mg-ADP plus Pi, and Mg-ATP . The dissociation constants were 9, 5, and 0.8 muM, respectively . The progressive tightening of the dissociation constants is symptomatic of conformational changes at the active site as the total subsite occupied by ATP is filled . The number of rapidly exchanging water molecules drops from 2 to approximately 0.1 when saturating concentrations of L-methionine (SR)-sulfoximine and nucleotide are present . The kinetically determined KI value of approximately 4 muM for the sulfoximine is about three orders of magnitude tighter than thee Km' value of approximately 3 mM for L-glutamate . The previously mentioned dissociation constants obtained by enhancement titrations are also orders of magnitude tighter than Km' . These data suggest that L-methionine (SR)-sulfoximine is a "transition-state" analogue for the glutamine synthetase reaction . ...

Science, 1976 Feb 6, 191(4226), 468 - 9
Characterization of a cell-lethal product from the photooxidation of tryptophan: hydrogen peroxide; McCormick JP et al.; Near-ultraviolet (300 to 400 nanometers) irradiation of saturated, oxygenated solutions of tryptophan in the absence of added sensitizer gives rise to substances that have various biological effects on isolated cells, including mutagenicity and selective lethality to recombination-deficient bacterial mutants . One of these biologically active products has been identified as H2O2, on the basis of spectrometric, chromatographic, chemical, and biological properties . Now H2O2 has been shown to account for the biological activities mentioned above.

Biochim Biophys Acta, 1976 Feb 5, 418(3), 315 - 20
Hydrodynamic determination of polynucleotide chain discontinuities . Improved molecular weight correlations for denatured DNA; Mingot F et al.; Evidence is presented of the constancy in the conformation of denatured DNA in 2% formaldehyde in SSC (0.15 M NaCl/0.015 M trisodium citrate (pH 7.0)) over a wide range of molecular weights . It is also shown that denatured RNA behaves in the same way as DNA . The range of molecular weights studied runs from 0.02 to 16 X 10(6) . In accordance with these results, biparametric expressions are proposed for molecular weight calculations from sedimentation or viscosity data of denatured DNA or RNA, when determined in 2% formaldehyde in SSC . Testing of the expressions with standard DNA and RNA preparations showed good correlation.

Biochim Biophys Acta, 1976 Feb 5, 418(3), 249 - 56
Informational complexity of the nuclear and chloroplast genomes of Chlamydomonas reinhardi; Howell SH et al.; DNA - DNA reassociation kinetics analyzed by hydroxylapatite chromatography have been used to determine the informational content of the Chlamydomonas reinhardi nuclear and chloroplast genomes . The kinetics indicate that nuclear DNA, with the exception of ribosomal cistrons, renatures as a single component with an informational complexity 25 times that of the Escherichia coli genome . The chloroplast genome has less than 0.3% of the informational complexity of the nuclear genome, but is present in about 50 copies in the vegetative cell . Chloroplast DNA shows about a 10-12% zero-time binding component.

Biochim Biophys Acta, 1976 Feb 5, 418(3), 266 - 76
Partial purification and properties of a DNA-binding protein from nuclei of cells infected with polyoma virus; Yeh WS et al.; A DNA-binding protein has been purified from nuclei of 3T3 cells infected with polyoma virus . The assay used to detect this activity measures the amount of double-stranded DNA retained on a nitrocellulose membrane filter in the presence of binding protein . The interaction between DNA and protein is salt dependent and occurs optimally at 0.8 M NaCl . The isolated protein can bind to both circular and linear duplex DNA . Incubation of the binding protein with PM2 or polyoma DNA results in the formation of a fast sedimenting DNA structure in neutral sucrose gradients . The isolated binding protein is also capable of producing a considerable stimulation of both Escherichia coli (Pol I) and T4 DNA polymerase activities when either single-stranded or intact, native T7 DNA is used as the template . The binding protein itself is free of detectable DNA polymerase or nuclease activity.

Eur J Biochem, 1976 Feb 2, 62(1), 189 - 92
The reconstitution of Anacystis nidulans DNA-dependent RNA polymerase from its isolated subunits; Herzfeld F et al.; The DNA-dependent RNA polymerase of the blud-green alga Anacystis nidulans was reconstituted from its isolated subunits in the absence of urea . Applying this technique the kinetics and the subunit requirements of the reconstitution process were analyzed . The results reveal differences with respect to the reconstitution of Escherichia coli polymerase . Reconstitution proceeds much more slowly in the case of the A . nidulans enzyme . Reconstitution here is absolutely dependent on the presence of the subunit sigma . On the other hand, the largest of the subunits of Mr=190000 can be fully substituted by a specific degradation product of this subunit of Mr=175000 . Heterologous reconstitution between subunits of E . coli and A . nidulans polymerase does not result in active enzyme hybrids, showing a divergent evolution of the structure of this enzyme in these procaryotic organisms.

Mol Gen Genet, 1976 Feb 2, 143(3), 339 - 44
R factor-mediated tetracycline resistance in Escherichia coli K12 . Dominance of some tetracycline sensitive mutants and relief of dominance by deletion; Foster TJ; Strains of Escherichia coli K12 heterozygous for the R100-1 tetracycline resistance region were constructed . They carried the wild-type Tetr genes in the chromosome and single site Tets mutations on plasmids . Some heterozygotes could not express tetracycline resistance fully after induction . The mutant tet allele was thus partially dominant . When heterozygotes carrying the dominant tet mutant were plated on agar containing 20 mg/ml tetracycline, mutants which grew normally occurred at a frequency of 1-4 X 10(-4) . Analysis of these dominance relief mutants showed that in 53/56 isolates the dominant tet allele was lost forming either Tra+ or Tra- deletion mutants of the plasmid . The mutation frequency was not affected either by the host chromosomal recA mutation or by the temperature of growth of the culture.

Mol Gen Genet, 1976 Feb 2, 143(3), 319 - 25
Characterisation of plasmids coding for the restriction endonuclease EcoRI; Smith HR et al.; The properties of two plasmids coding for the CcoRI restriction and modification enzymes are described . Both plasmids are non auto-transferring (NTP) but can be mobilised by transfer factors . Strains carrying NTP13 produce colicin E1 and the EcoRI enzymes . This plasmid has a molecular weight of 6 X 10(6) daltons and is present as approximately 12 copies per chromosome . The second plasmid, NTP14, was detected after mobilisation of the EcoRI plasmid with the R factor RI-19 . NTP14 codes for ampicillin resistance, synthesis of the EcoRI enzymes and colicin E1 . The molecular weight of NTP14 is 10.7 X 10(6) daltons and there are about 14 copies per chromosome . DNA-DNA reassociation experiments were performed to determine the interrelationships of NTP13, NTP14, ColE1 and the R factor R1-19 . NTP13 and NTP14 continue to replicate when cellular protein synthesis is inhibited by the addition of chloramphenicol.

Mol Gen Genet, 1976 Feb 2, 143(3), 297 - 9
Biosynthesis of Escherichia coli RNA polymerase subunits upon release of rifampicin inhibition; Engbaek F et al.; Upon release of rifampicin inhibition of Escherichia coli cells, the initiation of transcription will resume . The sequential resumption of the synthesis of proteins after release of rifampicin inhibition reflects the genetic order and size of the corresponding transcriptional units . We have used this approach to analyze whether the genes for alpha and sigma are on the same transcriptional unit as the genes for beta and beta', employing a method, which allowed us to measure the amounts of RNA polymerase subunits, alpha, beta, beta' and sigma in crude extracts . We have found that the alpha and sigma subunits are synthesized concurrently with the beta subunit in the rifampicin restart experiment, which suggests that the genes for alpha and sigma belongs to different transcriptional units.

Mol Gen Genet, 1976 Feb 2, 143(3), 243 - 52
Expression of a valine-resistant acetolactate synthase activity mediated by the ilv O and ilv G genes of Escherichia coli K-12; Favre R et al.; A strain carrying the ilv0603 mutation has been isolated in E . coli K-12 and its characteristics were found to be very similar to those previously reported by Ramakrishnan and Adelberg (1965a) for other ilv0 mutants . The strain carrying the ilv0603 mutation is resistant to valine inhibition (Valr) and we show that this resistance depends on the expression of a newly recognized gene, ilvG, which is located at min 75, between ilvE and ilvD on the E . coli K-12 map . The ilvG gene causes the expression of a Valr acetolactate synthase, which is detectable only when the ilv0603 mutation is also present in cis on the same chromosome . Under these conditions the Valr acetolactate synthase activity is eluted, on a hydroxylapatite column, at an ionic strength slightly lower than that required for elution of the remaining acetolactate synthase activity (sensitive to valine inhibition) . The Valr peak is missing in a strain carrying an ilvG (amber) mutation.

Mol Gen Genet, 1976 Feb 2, 143(3), 233 - 41
RNA polymerase mutants of Escherichia coli . III . A temperature-sensitive rifampicin-resistant mutant; Kawai M et al.; Temperature-sensitive mutants of Escherichia coli that are unable to grow at high temperature can be obtained among those selected for resistance to streptovaricin or rifampicin at low temperature (Yura et al., 1973) . One of these mutants (KY5323) that was supposed to carry a single mutation affecting both rifampicin resistance and temperature sensitivity was further investigated . Using purified RNA polymerase preparations obtained from the mutant and the wild type, it was found that the activity for RNA chain elongation is more sensitive to heat treatment than that for RNA chain initiation or DNA binding, and that the mutant enzyme is significantly more labile than the wild-type enzyme with respect to RNA chain elongation, when heat treatment is carried out at high salt concentration . These results, taken together with those of the enzyme reconstitution experiments, strongly suggest that the beta subunit of the polymerase is directly involved in both RNA chain initiation and elongation reactions . Enzyme reconstitution experiments using isolated subunits derived from the mutant and the wild-type polymerases demonstrate that the alteration of beta subunit is primarily responsible for both rifampicin resistance and thermolability of the mutant enzyme . In addition, the results suggested the apparent alteration of both beta and alpha subunits in this mutant . Extensive transduction experiments provided genetic evidence that are consistent with the view that the strain KY5323 carries a second mutation affecting the beta subunit, beside the primary mutation affecting the beta subunit . The hypothetical beta subunit mutation seems to modify quantitatively the rifampicin resistance caused by the beta subunit mutation.

Eur J Biochem, 1976 Feb 2, 62(1), 117 - 23
The involvement of protein L11 in the joining of the 30-S initiation complex to the 50-S subunit; Naaktgeboren N et al.; Ribosomal protein L11 participates in the coupling of the 30-S initiation complex with the 50-S subunit . P37 cores, lacking L7, L8, L12, L33, L10 and L11 were reconstituted with L7 and L10 . These particles are unable to join successfully to the 30-S initiation complex, whereas reconstitution of the same cores in the presence of L7, L10 and L11 restores 60-80% of the original coupling activity . P0 cores lacking only L7, L8, L12 and L33 are able to carry out one round of initiation, addition of L7 resulting in complete restoration of full activity . The data obtained with these P37 core particles resemble those obtained with untreated 50-S particles carrying thiostrepton, which prevents the binding of initiation factor IF-2 into the 70-S initiation complex . It is postulated that L11 induces a niche on the ribosomal surface to facilitate the proper binding of the IF-2 X GTP X fMet-tRNA complex . This binding of IF-2 enables the 30-S initiation complex to join to the 50-S subunit, because of the associative ability of IF-2 . If joining is impaired than both the level of fMet-tRNA binding and of the IF-2-mediated GTP hydrolysis is lowered.

J Pharmacol Exp Ther, 1976 Feb, 196(2), 469 - 77
Studies on the binding of 5,5-diphenyl-hydantoin to nucleic acids in vitro and to rat brain subcellular fractions in vitro and in vivo; Boykin ME et al.; The binding of 5,5-diphenylhydantoin (DPH) to nucleic acids (bovine brain RNA, rat liver ribosomal and tRNA, Torula utilis RNA, and calf thymus and Escherichia coli DNA was studied using ultraviolet spectroscopy, gel chromatography and thermal transition profiles . Within the sensitivity of these methods, it was found that there is essentially little or no interaction between DPH and nucleic acids in vitro as has been reported previously . Little, if any evidence of DPH intercalation with DNA was noted during thermal transition studies . DPH does not interfere with DNA reassociation . Further studies into the nature of the in vivo subcellular distribution of 14C-DPH in rat brain revealed accumulation of the radioactivity primarily in the soluble fractions . The nuclear fraction and the microsomes, containing high DNA and RNA tissue ratios, demonstrated the greatest particulate association with radioactivity at 2 and 12 hours, respectively . This association with particulate fractions was not demonstrated after gel chromatography . These data do not support a hypothesis relating DPH binding to nucleic acids in vitro or in vivo to a possible mechanism of action of the drug.

Proc Natl Acad Sci U S A, 1976 Feb, 73(2), 415 - 9
Studies on nucleic acid reassociation kinetics: empirical equations describing DNA reassociation; Britten RJ et al.; The rate of appearance of duplex DNA renaturation, measured with single strand specific nuclease, deviates significantly from a second order reaction . Measurements reported in paper I of this series indicate an inhibition in the rate of reassociation of single strand tails on partially reassociated molecules by a factor of at least two . Equations are derived that describe the observed form of reassociation kinetics as measured with hydroxyapatite and with single strand specific nuclease . The free parameter that describes the extent of inhibition of nucleation with single strand tails in these equations has been evaluated by least squares methods and agrees with the experimentally measured value.

J Lab Clin Med, 1976 Feb, 87(2), 251 - 9
Autoantigens in human sweat: purification and characterization of the D-group antigens; Silpananta P et al.; We have found several heteropolysaccharides in human thermal sweat which are both autoantigenic and isoantigenic for a majority of healthy adults . They are present in trace amounts and are difficult to isolate . We have facilitated extraction through the use of a DEAE-Sephadex batch technique . One of the major antigenic fractions, the D group, has been purified and characterized . It contains 88.5 per cent carbohydrate as uronic acid, hexosamine, methyl pentose, and glucose . The protein content was 12.5 per cent.

J Infect Dis, 1976 Feb, 133(2), 153 - 6
Enteropathogenic Escherichia coli: lack of correlation of serotype with pathogenicity; Goldschmidt MC et al.; Forty-eight strains of Escherichia coli isolated from children with diarrhea were classified according to nine enteropathogenic serotypes . The strains were examined for production of enterotoxin and for invasiveness by study of bacteria or bacteria-free filtrates in conventional animal and tissue culture models . Filtrates of only three strains (6%) consistently dilated rabbit ileal loops, while all 48 strains yielded negative results in suckling mice, adrenal cells, and guinea pig eyes . When filtrates of the three strains that dilated the rabbit ileum were heated at 60 C for 30 min, the reaction in rabbit ileal loops was negative; this finding indicated the production of a heat-labile enterotoxin . This study shows the lack of correlation between classical enteropathogenic serotypes of E . coli and presently known virulence properties in animal models . The results raise doubts about the value of serotyping E . coli isolates from sporadic cases of diarrhea . When it is suspected that an E . coli isolate is enteropathogenic, it may be important to perform more than one laboratory assay.

J Bacteriol, 1976 Feb, 125(2), 713 - 8
Analytical isoelectric focusing of R factor-determined beta-lactamases: correlation with plasmid compatibility; Matthew M et al.; R factor-determined beta-lactamases have been investigated by analytical isoelectric focusing . The enzymes such as those specified by the R6K and RP4 plasmids (TEM-type enzymes) are notably homogenous in biochemical tests (Hedges et al., 1974), but two subclasses can be distinguished by isoelectric focusing . Three subclasses can be distinguished among the oxacillin-hydrolyzing enzymes, in good agreement with the classification based upon biochemical characteristics (Dale and Smith, 1974) . The TEM-type beta-lactamases are promiscuously distributed among plasmids of a wide variety of compatibility groups, whereas the various oxacillin-hydrolyzing enzymes show some degree of correlation with compatibility.

J Bacteriol, 1976 Feb, 125(2), 670 - 8
Adaptation of membrane lipids to alcohols; Ingram LO; The effects of alcohols of different chain lengths on the fatty acid composition of Escherichia coli K-12 have been examined . My results indicate that these cells radically change their fatty acid composition when grown in the presence of alcohols . These changes represent an adaptive membrane alteration compensating for the direct physicochemical interaction of alcohols with the membrane . Similar adaptive responses of membrane lipids are proposed as a possible biochemical basis for tolerance to alcohol and related drugs.

J Bacteriol, 1976 Feb, 125(2), 540 - 44
Evidence for the involvement of ribonucleic acid in the production of F pili; Fives-Taylor P et al.; The effects of rifampin and streptolydigin, inhibitors of ribonucleic acid (RNA) synthesis, on the production of F pili by Escherichia coli were studied by electron microscopy . The inhibition of RNA synthesis reduces the number of new pili produced by depiliated cells, but does not affect their length or the number of pili present at the time of inhibition or the retraction of pili . We suggest that the rifampin-sensitive step may be linked to the establishement of a site for pili production . Evidence is provided that chloramphenicol inhibits retraction . We suggest that retraction requires some protein whose pool size is limited.

J Bacteriol, 1976 Feb, 125(2), 423 - 8
H2-dependent anaerobic growth of Escherichia coli on L-malate: succinate formation; Macy J et al.; Escherichia coli grew anaerobically on L-malate only in the presence of H2; 91% of the L-malate utilized was converted to succinate . Anaerobically isolated membrane vesicles catalyzed the reduction of fumarate with H2 and contained a b-type cytochrome . Cytochrome c552 was present in the "periplasmic space."

J Biochem (Tokyo), 1976 Feb, 79(2), 289 - 92
Studies of enzyme-catalyzed modification of proteins . I . Tyrosinase-catalyzed modification of asparaginase; Tokushige M et al.; Asparaginase {EC 3.5.1.1.} of Escherichia coli, an anti-tumor enzyme, was inactivated in a time-dependent fashion by mushroom tyrosinase {EC1.14.18.1.} . The inactivation did not proceed, however, when heat-inactivated tyrosinase was used . Exculusion of the atmospheric oxygen or addition of diethyldithiocarbamate, a copper selective chelating agent, prevented the inactivation . The difference absorption spectrum of tyrosinase-inactivated asparaginase versus intact asparaginase exhibited the appearance of marked absorption peaks at 300 and 350 nm . These results indicate that the tyrosyl residue(s) of asparaginase, which is essential for the activity is enzymatically modified by tyrosianes.

Nucleic Acids Res, 1976 Feb, 3(2), 371 - 80
Comparative base compositions of chloroplast and cytoplasmic tRNAPhe's from Euglena gracilis; Hecker LI et al.; The nucleoside compositions of chloroplast and cytoplasmic tRNAPhe's from Euglena gracilis have been determined . The modified nucleoside compositions of these two tRNAs indicate that tRNAPheChl is more similar to procaryotic (E . coli) tRNAPhe than to either the Euglena cytoplasmic tRNAPhe or other eucaryotic cytoplasmic tRNAPhe's.

J Natl Cancer Inst, 1976 Feb, 56(2), 333 - 8
Altered immunologic responsiveness in mastocytoma-bearing mice; Kamo I et al.; Immune responses to sheep erythrocytes were enhanced in mice bearing small mastocytomas soon after injection of a few tumor cells . In contrast, mice with larger tumors after transfer of a greater number of mastocytoma cells and those in the later stages of tumor development after transfer of small numbers of tumor cells showed moderately suppressed immune responses . Transfer of spleen cells from mastocytoma-bearing mice to irradiated recipients resulted in more antibody-forming cells as compared to transfer of splenocytes from normal donor mice . The addition of graded numbers of mastocytoma cells to a constant amount of normal spleen cells transferred to irradiated mice also resulted in enhanced responses and increased spleen weights in the recipients . This increase, in direct proportion to the number of mastocytoma cells transferred, also occurred when Escherichia coli lipopolysaccharide (a T-cell independent antigen) was used to immunize animals given spleen cells from normal mice and mastocytoma cells . Mastocytoma cell-free homogenates or X-irradiated tumor cells also heightened immune responses in recipient mice, which indicated that viable cells were not needed for the effect . Such homogenates, as well as the tumor cells per se, stimulated increased lactate dehydrogenase (LDH) activity in the sera of recipient mice . However, tumor cells passaged in tissue culture for several months, those derived from mice bearing a mastocytoma cell line with a low LDH-stimulatory activity, or UV-irradiated mastocytoma cells with a high LDH-stimulatory activity did not induce enhanced plaque-forming cell responses.

J Med Chem, 1976 Feb, 19(2), 342 - 4
Racemic diastereoisomers of 1-amino-2-hydroxycyclopentanecarboxylic acid; Gaitanopoulos DE et al.; The synthesis and characterization of the two diastereoisomeric forms of 1-amino-2-hydroxycyclopentanecarboxylic acid have been accomplished . A previously reported synthesis produced a racemic mixture of the threonine analog trans-2-hydroxy-1-aminocyclopentanecarboxylic acid (trans with respect to the hydroxy and carboxyl group) . The alternate allothreonine analog was produced by conversion of cyclopentene oxide to trans-2-methoxycyclopentanol, followed by oxidation to 2-methoxycyclopentanone and conversion to a hydantoin . Fractional crystallization of the hydantoin sample, followed by hydrolysis, produced cis-2-hydroxy-1-aminocyclopentanecarboxylic acid (cis with respect to the hydroxy and carboxyl group) in high purity . Neither of the isomeric forms significantly inhibited the growth of the bacterial strains examined nor were they effective in inhibiting Jensen sarcoma cells in tissue culture.

J Pediatr Surg, 1976 Feb, 11(1), 23 - 30
Endotoxin clearance after intralipid infusion; Tovar JA et al.; Healthy 6-8-wk-old New Zealand white rabbits were injected with chromium-chloride- or sodium-chromate-labeled E . coli endotoxin after rapid infusion (10 ml/kg in 1 hr) or slow and repeated infusions (40 ml/kg daily for 7 consecutive days) of 10% Intralipid . Endotoxin clearance rates and RES organ uptakes were determined and the results were compared with those of the controls treated with correspondingly equal volumes of 5% D/W instead of fat . In the acute experiment, the clearance rates were similar in all animals during the first 15 min following endotoxin injection . After this phase, however, experimental animals had faster endotoxin clearance and eventually higher organ uptakes than the controls . In the chronic experiment, there was no significant difference in endotoxin clearance rates or total and per-gram organ uptakes between experimental and corresponding control animals infused with 5% D/W instead of fat . Experimental animals, particularly those having received multiple infusions of fat emulsion, showed deposition of polarizable brown pigment inside and outside the reticuloendothelial cells in the liver, spleen, and bone marrow . None of the controls had these pigments in their organs.

Jpn J Med Sci Biol, 1976 Feb, 29(1), 25 - 37
Further studies on the lethal effect of long-chain fatty acids on mycobacteria; Kondo E et al.; Mycobactericidal activity of long-chain fatty acids was confirmed by in vitro exposure of BCG . The killing effect was accompanied by inhibition of the membrane-bound acid phosphatase activity . Such active fatty acids were those having a stronger hemolytic activity (e.g., C12:0, C14:0, C18:1, C18:2) . Heat-killed BCG cells or their cell walls adsorbed the toxic fatty acids, whereas the fatty acid-insensitive E . coli cells did not . It was suggested that the mycobactericidal action of long-chain fatty acids is due to their detergent-like action on the cytoplasmic membrane, and that the determinant factor for the fatty acid-sensitivitiy of bacteria is the property of the cell wall by which fatty acids are adsorbed so that the active site is brought into contact with the inner membrane.

Cell, 1976 Feb, 7(2), 205 - 12
A temperature-sensitive suppressor enabling the manipulation of the level of individual proteins in intact cells; Oeschger MP et al.; A temperature-sensitive suppressor strain of E . coli has been isolated and characterized . The properties of the mutant indicate a strong potential for its use in biochemical and genetic work . In particular, the mutant makes possible the variation of the intracellular concentration of selected protein, permitting an evaluation of its role in cell growth and biochemistry . The mutant also permits the selective radiochemical labeling of proteins in vivo for in vitro identification and analysis . The utilization of the mutant for these and other applications is discussed.

Agents Actions, 1976 Feb, 6(1-3), 251 - 5
In vivo and in vitro macrophage activation by systemic adjuvants; Bruley-Rosset M et al.; Six systemic adjuvants of immunity were tested for their ability to induce macrophage activation . Four of them: living BCG, hydrosoluble extracts from BCG (HIU II) and from M.smegmatis (IPM), and lipopolysaccharide from E.coli (LPS), when administered to normal mice render macrophages non-specifically cytotoxic for tumor cells in vitro . The intensity of this phenomenon varied according to the route and time of adjuvant administration . In contrast, lentinan extracted from Lentinus edodes, and levamisole which is a synthetic chemical compound, depressed macrophage cytotoxic potential . BCG, IPM and LPS were shown to have a direct action on macrophages . After in vitro exposure to these agents, the cytotoxic potential of normal macrophages was greatly increased . Levamisole was unable to stimulate this macrophage function directly in vitro . On the other hand, such a macrophage activation has been induced in vitro when normal macrophages were cultivated in the presence of MIF coming from the supernatant of human lymphoblastoid cell lines.

Arzneimittelforschung, 1976 Feb, 26(2), 187 - 9
{Spontaneous peripheral proteolysis/2nd communication: Effect of peripheral proteolysis (author's transl)}; Greuer W et al.; With the modified Astrup-plate method a spontaneous peripheral proteolysis was often found in chronical infections of the skin and mucous membranes . The origin of this proteolysis and its effects on the bacterial growth and wound healing were discussed.

J Biochem (Tokyo), 1976 Feb, 79(2), 305 - 11
Dessociation and reconstitution of colicin E3 and immunity substance complex; Hirose A et al.; It has recently been found that so-called native colicin E3, which has been used for studies of its mode of action, is a complex of two kinds of proteins . The complex could be dissociated into the two components in SDS . These components were isolated by gel filtration of 1% SDS followed by treatment with Sowex-2 to remove bounds SDS . One component, characterized by its low molecular weight, prevented colicin E3-induced inhibition of poly(U)-dependent protein synthesis and was designated as immunity substance . The other component (protein A), which was of high molecular weight, had 100-fold higher in vitro ribosome-inactivating activity than native colicin E3, but had lower bacteriocidal activity . Colicin E3 was reconstituted from the two isolated protein components . The reconstituted colicin E3, when compared with protein A, showed a decrease in in vitro activity (inhibition of poly(U)-dependent protein synthesis), but had higher bacteriocidal activity in vivo . Thus complex formation of protein A with immunity substance should play and important role in the bacteriocidal action, but protein A itself might inactivate ribosomes in the interior of the sensitive cells.

Jpn J Antibiot, 1976 Feb, 29(2), 189 - 96
{Clinical studies with amoxicillin (Pasetocin) (author's transl)}; Ito K et al.; This paper describes briefly the results obtained with AMPC (Pasetocin) administered by oral route to 21 patients with infection of the respiratory tract . 1 . There was no difference in therapeutic effect on infection of the respiratory tract between daily dosages of 1,000 mg and 750 mg (the former was orally given in 4 divided doses every 6 hours a day and the latter in 3 divided doses after meal) . The response of the patients to AMPC was remarkable or satisfactory . 2 . Acute aggravation symptoms associated with chronic infection of the respiratory tract showed similar improvement to single acute infection of the respiratory tract . 3 . The patients presenting acute aggravation symptoms received treatment for chronic stage consisting of consecutive oral administration of AMPC (500 approximately 750 mg a day) and their prognosis was favorable . Side effects attributable to prolonged treatment were not noted . 4 . The incidence of side effects can be reduced largely by rejecting form AMPC therapy the patients who are hypersensitive to drugs including penicillins.

Infect Immun, 1976 Feb, 13(2), 533 - 42
Changes in lactoferrin, immunoglobulin G, bovine serum albumin, and alpha-lactalbumin during acute experimental and natural coliform mastitis in cows; Harmon RJ et al.; An experimentally induced Escherichia coli infection of a bovine mammary gland resulted in a 30-fold increase in lactoferrin (Lf) concentration in the mammary secretion by 90 h postinoculation and a 4-fold increase in total daily production of Lf by 264 h postinoculation in the infected quarter . A simultaneous rise and fall of bovine serum albumin (BSA) and immunoglobulin G (IgG) concentrations occurred during the acute phase of the infection . Peak BSA and IgG levels were reached 36 h before peak Lf levels . BSA concentrations declined rapidly after the acute phase, whereas IgG and Lf levels remained elevated and decreased slowly as the infection subsided . A decline in alpha-lactalbumin concentration by 48 h postinoculation indicated decreased synthetic capability . The increased Lf production may be a result of a specific response of secretory tissue to inflammatory agents and thus the infectious process . Analogous changes in Lf, IgG, and BSA were observed during a natural coliform infection . Sephadex G-200 chromatography of mastitis skim milk showed that Lf approximated the monomer (molecular weight 77,100) early in infections progressed and abated, the apparent molecular weight of Lf increased to approximately that of the trimer and subsequently decreased to about 1.5 times that of the monomer.

Infect Immun, 1976 Feb, 13(2), 448 - 56
Effect of estradiol on immune competence: in vivo and in vitro studies; Kenny JF et al.; The administration of a single dose of 2.5 mug of microcrystalline estradiol-17 beta from 1 day before and up until 3.5 days after the administration of 3 X 10(5) heat-killed Escherichia coli significantly increased numbers of splenic anti-E . coli antibody-producing cells in male mice sacrificed 4 days after receiving anitgen . Administration early in the proliferative phase of antibody production, i.e., 1 day before or 1 day after the antigen, appeared to increase numbers of antibody-producing cells more than when it was administered at a later time . When given 2 days before the antigen or 2 h before sacrifice no effect was observed . Spleen cells harvested from male animals injected 3 days before with 5 X 10(6) heat-killed E . coli were incubated for 24 h in vitro with estradiol in concentrations ranging from 5 pg to 20 ng/ml . With concentrations of 500 pg to 5,000 pg/ml, significant increases in antibody-producing cells occurred, whereas at concentrations of 20 ng/ml some decrease was observed . The increase in antibody-producing cells was blocked by a mitotic inhibitor . Significant changes in numbers of antibody-producing cells were not observed after a 2-h incubation period . Uptake of titrated thymidine was increased in thymic and spleen cells incubated for 24 h with 500 pg of estradiol per ml; a concentration of 20 ng/ml slightly (but insignificantly) decreased uptake . Findings suggest that estradiol, in concentrations that approximate physiological serum levels in females, enhances mitosis of immunocompetent cells . This phenomenon may have bearing on the better immunological responsiveness of females than males.

Can J Biochem, 1976 Feb, 54(2), 192 - 3
Ribosomal RNA: the message or matrix for ribosomal proteins; Miller DR et al.; The known nucleotide sequence of Escherichia coli 16S ribosomal RNA has been converted to amino acid sequences in all possible ways, and compared to known ribosomal protein sequences . The degree of similarity is precisely what one would expect by chance alone, providing additional evidence that ribosomal proteins cannot be coded for by ribosomal RNA.

Am J Vet Res, 1976 Feb, 37(2), 159 - 63
Local immune responses in the bovine fetus vaccinated in utero with Escherichia coli antigen; Wamukoya JP et al.; Using specific immunofluorescent examinations, the local immune responses were studied in 14 calves prenatally vaccinated (10 to 50 days before birth) with Escherichia coli (O26:K60:NM) antigen or sterile saline solution . All calves were colostrum-deprived, were given oral doses of homologous organisms (killed or live), and were necropsied either at birth or within 12 days after birth . Immunofluorescent plasma cells were not seen in duodenum, jejunum, jejunal lymph nodes, ileum, ileal lymph node, or spleen of control calves prenatally vaccinated with sterile saline solution . All of these tissues, except ileal lymph node, from calves vaccinated in utero with E coli showed fluorescence . Jejunum, jejunal lymph node, and ileum had the greatest number of immunofluorescent plasma cells . There were more immunoglobulin G2-than immunoglobulin M-producing cells . The cells producing specific antibodies against E coli (1 calf studied) comprised approximately 33% of the total number of immunofluorescent cells.

Proc Natl Acad Sci U S A, 1976 Feb, 73(2), 317 - 21
Identification of biological molecules in situ at high resolution via the fluorescence excited by a scanning electron beam; Hough PV et al.; Proteins, nucleic acids, and fluorescein-conjugated antibody are shown to be identifidable in situ via the fluorescence excited by the focused electron beam of a canning electron microscope . A molecular species is identified by its characteristic fluorescence spectrum and by a characteristic alteration of the spectrum with time under the electron beam . Primary protein fluorescence is relatively rapidly destroyed by the beam, but protein photoproduct fluorescence is more rugged and will in some cases permit detection of small numbers of protein molecules . Nucleic acid fluorescence is extremely long-lived and will permit detection of small numbers of nucleic acid residues . The theoretical resolution limit for localization of a particular molecular species -- about 20 A--is determined by the known maximum distance for molecular excitation by fast electrons . Drect extapolation from an observed resolution of 900 A in the localization of nucleic acid using a low-efficiency detector leads to an experimental resolution limit of less than 60 A . Fluorescence is strongly quenched by residual water in the specimen . Similar quenching is produced by some macromolecular associations and so may serve to localize such associations.

Mutat Res, 1976 Feb, 38(1), 33 - 42
Use of a simplified fluctuation test to detect low levels of mutagens; Green MH et al.; As a mutagen screening procedure we have used a modification of the Luria and Delbruck fluctuation test in which the individual tubes are scored by eye for the presence or absence of a mutation . The test is simple and extremely sensitive, detecting concentrations of mutagens up to 100-fold lower than conventional tests . Measuring mutation to tryptophan independence in Escherichia coli strain WP2 we have found that methyl methanesulphonate (0.5 mug/ml), mitomycin C (0.0015 mug/ml), dichlorvos (5 mug/ml, and K2CrO4 (0.5 mug/ml) are all positively mutagenic in the test, whereas NiCl2 is negative . Chronic exposure to low levels of mutagens using this method appears to induce more mutations than might be predicted by extrapolation from short exposure experiments at higher doses . The procedure is applicable to any system which involves mutation to prototrophy from a non-leaky auxotrophic requirement and should prove valuable in detecting and investigating the effects of low doses and chronic exposures.

Mutat Res, 1976 Feb, 38(1), 3 - 32
Mutagen testing using TRP+ reversion in Escherichia coli; Green MH et al.; Escherichia coli strain WP2 and its repair-deficient derivatives are suitable strains for mutagen screening . In these strains, agents which cause base substitution mutations can be shown to increase the frequency of Trp+ revertants . In addition, agents causing many types of DNA damage can be detected through increased killing of the repair deficient derivatives . Four ways of performing tests are described: (a) Spot tests in which a small amount of the agent under test is placed directly on a selective agar plate . Trp+ revertants are counted and increased sensitivity of repair-deficient strains determined from the size of the zone of inhibition of cell growth . (b) Treat and plate tests, where a strain is treated with the agent under test and subsequently plated to determine survival or frequency of Trp+ revertants . (c) A simplified fluctuation test which shows exceptional sensitivity in measuring mutation with low levels of mutagens . (d) Use of a liver microsomal fraction in conjunction with treat and plate tests to detect metabolically activated mutagens . The merits and defects of these systems are discussed . Common pitfalls in evaluating tests and procedures for avoiding them are described.

Am J Surg, 1976 Feb, 131(2), 213 - 8
Gunshot wounds of the colon . A review of 100 consecutive patients, with emphasis on complications and their causes; Haygood FD et al.; The cases of one hundred civilian patients with gunshot wounds of the colon treated at the Louisville General Hospital have been reviewed . Most injuries were in the transverse colon (44%), followed by the ascending colon (27%), rectosigmoid (19%), and descending colon (10%) . Associated injuries occurred in 81 per cent of the patients; the small bowel was the most common structure injured . Primary closure was used in 52% of the patients, with a resultant 19% rate of wound infection and 14% rate of serious complication . When the extent of contamination or tissue destruction required resection, an attempted primary anastomosis was followed by a high rate of wound infection (57%) and serious complications (36%) as compared with end-colostomy and mucous fistula, which resulted in a 24% rate of wound infection and 24% rate of serious complication . The rate of wound infection between these groups is significant (p = 0.05) . Results end-colostomy and mucous fistula were better than with attempted primary anastomosis.

Proc Soc Exp Biol Med, 1976 Feb, 151(2), 329 - 32
Endotoxin toxicity in rats is enhanced by tilorone; Levine S et al.; The relatively nontoxic drug, tilorone, greatly enhanced the susceptibility of rats to lethal effects of endotoxin . The magnitude of the synergy was similar to that produced by adrenalectomy, but the effect of tilorone was not mediated by the adrenal glands . The histopathologic effects of endotoxin plus tilorone resembled those produced by much larger doses of endotoxin alone, including instances of the generalized Shwartzman reaction.

Proc Soc Exp Biol Med, 1976 Feb, 151(2), 271 - 4
Inhibition by nalidixic acid of post-uv survival of Escherichia coli; Nishida M et al.; Nalidixate inhibited the post-uv survival of E . coli B . TAU-bar and Ts-7, but not Bs-1 or B/r when included in the plating medium . Removal of the drug sensitivity by photoreactivation was consistent with pyrimidine dimers as the target for the effect . Nalidixate did not inhibit liquid-holding recovery from uv when included in the holding medium, but survival was inhibited if the drug was in the subsequent plating medium . In fact, there was an actual increase in the number of nonsurvivors due to the drug following a period of holding.

J Immunol, 1976 Feb, 116(2), 379 - 86
The in vitro suppression of antigen- or mitogen-induced DNA synthesis by murine spleen cells after the addition of freshly prepared syngeneic cells; Ficho TW et al.; The suppression of antigen- and mitogen-induced DNA synthesis by murine spleen cells in vitro was investigated . It appears that cultures receiving two signals exhibit marked suppression of DNA synthesis . The addition of KLH, PPD, Con A, PHA, or LPS to 72-hr-lod cultures of KLH-stimulated murine spleen cells resulted in the suppression of DNA synthesis assayed at 144 hr . When small numbers of freshly prepared KLH-PPD SC or NSC were added to these cultures at 72 hr the suppression of DNA synthesis was abrogated . However, the addition of larger numbers of KLH-PPD SC or NSC resulted in increased suppression of DNA synthesis . Large numbers of KLH-PPD SC or NSC could substitute for the second stimulant (KLH, PPD, Con A, PHA, or LPS) in suppressing DNA synthesis . The addition of fresh cells obtained from KLH-PPD-immunized mice were more effective in eliciting the subsequent suppression than were cells obtained from non-immunized mice . Cells obtained 30 to 75 days post immunization were most effective in suppressing DNA synthesis.

J Am Vet Med Assoc, 1976 Feb 1, 168(3), 231 - 2
Effect of supplemental dietary vitamin E on the serologic response of swine to an Escherichia coli bacterin; Ellis RP et al.; Three groups of 10 pigs (6 to 8 weeks old) were fed a nutritionally complete ration (control ration, CR), CR plus 20,000 IU of vitamin E/ton (CR + recommended E), and CR plus 100,000 IU of vitamin E/ton (CR + high E), respectively . Each pig was given an intramuscular injection of an Escherichia coli bacterin at experimental days 0 and 35 . Serums were collected 7 days prior to the first injection and at days 7, 14, 21, 35, 42, 49, and 56 . Pigs fed the CR + high E ration developed anti-E coli serum antibody titers two- to threefold higher than those of the controls . Pigs fed the CR + recommended E ration developed serum antibody titers intermediate between those of pigs in the other 2 groups.

Chem Biol Interact, 1976 Feb, 12(2), 211 - 20
Removal of minor methylation products 7-methyladenine and 3-methylguanine from DNA of Escherichia coli treated with dimethyl sulphate; Lawley PD et al.; Persistence of methylpurines in DNA methylated in vitro and in vivo in Escherichia coli WP2 cells, by dimethyl sulphate (DMS) was studied, with particular reference to the minor products 7-methyladenine and 3-methylguanine, not previously investigated in this respect, but known to be removed from DNA in vitro by spontaneous hydrolysis at neutral pH . The half-life of 7-methyladenine in vivo was relatively short (2.6 +/- 0.2 h) but not significantly shorter than in vitro at pH 7.2, 37 degrees C . The half-life of 3-methylguanine was 3.6 +/- 0.3 h in vivo, markedly shorter than in vitro, where its stability was somewhat greater than that of 7-methylguanine . Enzymatic excision of 3-methylguanine was therefore indicated to occur in E . coli . Previous findings that 7-methylguanine is probably not enzymatically excised from DNA in vivo, whereas 3-methyladenine is rapidly removed, were confirmed, and additional support for the concept of enzymatic removal of 3-methyladenine was obtained by showing extensive inhibition of its removal from cells treated with iodoacetamide prior to methylation . It is suggested that methylations of adenine or guanine in DNA at N-3 constitute blocks to template activity of DNA and stimulate a "repair" response of enzymatic removal of 3-methylpurines . Possible valence bond structures for 3-methylpurine residues in DNA are discussed, leading to the suggestion that ionized forms with positively charged amino groups may be the most effective blocks to template activity.

Biokhimiia, 1976 Feb, 41(2), 357 - 62
{Escherichia coli membrane-bound polyphosphatase}; Severin AI et al.; A complex of polyphosphatase with E . coli membranes has been isolated and studied . It is shown by gel-filtration through G-200 Sephadex and centrifugation in sucrose concentration gradient that about 5% of polyphosphatase total content in cells is bound with the heterogenous fraction containing smooth membranes and the ribosome-membrane complex . On the basis of the data obtained it is suggested that the formation of a complex of polyphosphatase with membranes is a stage of synthesis and secretion of this enzyme to protoplasm.

Infect Immun, 1976 Feb, 13(2), 332 - 6
Interferon-producing capacity of germfree mice; Ito Y et al.; The general capacity of germfree mouse spleen cells to produce interferon in vitro in response to various stimuli was investigated . The interferon response of germfree mouse spleen cells in vitro, when compared with that of the conventionals, appears to be lower to some inducers . Interferon production in vitro stimulated by hemagglutinating virus of Japan (HVJ) or BHK-HVJ cells (BHK cells persistently infected with HVJ) was apparently suppressed in germfree mouse spleen cells as compared with the corresponding conventionals, whereas no difference of interferon production was observed between germfree and conventional mouse spleen cells in response to Newcastle disease virus, Escherichia coli endotoxin, poly(I:C), and phytohemagglutinin . Although monocontamination with HVJ had no enhancing effect on the interferon-producing ability of germfree mouse spleen cells in response to HVJ, conventionalization for 2 weeks greatly enhanced interferon-producing capacity.

Scand J Haematol, 1976 Feb, 16(2), 144 - 53
Function of granulocytes with deficient myeloperoxidase-mediated iodination in a patient with generalized pustular psoriasis; Stendahl O et al.; The granulocytes of a patient with generalized pustular psoriasis (GPP) were found to have impaired ability to fix iodine after ingestion of yeast particles . Since hexose monophosphate shunt (HMS) activity was increased and the contents of 3 other lysosomal enzymes, beta-glucuronidase, N-acetyl-beta-glucosaminidase and lysozyme, were within normal range, the impaired iodination appeared to be due to a selective defect of myeloperoxidase (MPO) activity within the phagocytic cells . The deficient iodination was accompanied by a decreased intracellular killing of E . coli and C . albicans . Since hexose monophosphate shunt activity was enhanced and azide and cyanide inhibited the intracellular killing of E . coli only moderately, the patient's granulocytes may possess azide- and cyanide-resistant, MPO-independant microbicidal systems coupled to the oxidative metabolism . Assessment of granulocyte iodination and enzyme contents of the relatives of the patient revealed no hereditary transmission . Since GPP is characterized by the development of subcorneal pustules containing granulocytes, the MPO-deficiency may be the cause of or enhance the development of the disease.

J Virol, 1976 Feb, 17(2), 614 - 21
Simian virus 40 DNA replication: characterization of gaps in the termination region; Chen MC et al.; A class of precursor DNA (pDNA) II molecules has been identified as the immediate precursor of simian virus 40 DNA I . A pDNA II molecule contains a strand of newly synthesized DNA with an interruption located in the region where DNA synthesis terminates (4) . These pDNA II molecules have been isolated and further characterized . They are converted to covalently closed structures (simian virus 40 DNA I) only when they are treated in vitro with both T4 DNA polymerase and Escherichia coli ligase . After in vitro repair of pDNA II with T4 DNA polymerase and nucleoside triphosphates, approximately 7 mol of alpha-{32P}dATP is incorporated per mol of DNA II . Alkaline sucrose analysis of these gap-filled molecules, after they have been cleaved with Eco RI restriction endonuclease, has demonstrated that gaps are specifically located in the termination region . alpha-{32P}dATP is incorporated equally into the two labeled products that are generated by RI cleavage of these molecules . This indicates the presence of gaps in both the newly synthesized plus the minus strands . Electrophoretic analysis of the gap-filled molecules, after they have been cleaved with endonuclease Hind, has shown that gaps are localized in Hind fragments G and B and to a minor degree in fragment J . pDNA II molecules have the following properties . There is a gap in the newly synthesized linear DNA strand contained in the pDNA II molecule . Nicked pDNA II molecules cannot be detected . The two molecules that arise by segregation contain gaps in both of the complementary strands . Based on the amount of alpha-{32P}dATP incorporated and the rate of exonuclease III digestion of gap-filled molecules, it is estimated that the size of the gaps is between 22 and 73 nucleotides . Models for termination of DNA synthesis are proposed based on these findings.

Proc Natl Acad Sci U S A, 1976 Feb, 73(2), 366 - 70
"Early" simian-virus-40-specific RNA contains information for tumor antigen formation and chromatin replication; Graessmann M et al.; Simian virus 40 (SV40) induces tumor (T)-antigen formation, chromatin replication, and mitosis in primary mouse kidney cells arrested in G0 phase of the mitotic cycle . The temporal and quantitative relation between these early virus-specific reactions led to the hypothesis that the early SV40 mRNA contains information necessary for T-antigen formation and induction of cellular DNA synthesis . To get direct experimental evidence for this hypothesis, the early strand of SV40 DNA was transcribed in vitro by Escherichia coli DNA-dependent RNA polymerase and the SV40-specific cRNA was transferred by microinjection into epitheloid cells of confluent primary mouse kidney cultures . T-antigen formation and stimulation of DNA synthesis were investigated in the recipient cells . The experimental results obtained agree with the hypothesis that T-antigen is a virus-coded protein and that the early virus-specific mRNA contains information necessary for stimulation of cellular DNA replication in the arrested cells.

J Bacteriol, 1976 Feb, 125(2), 575 - 80
Suppressor-induced structural changes in a missense L-ribulokinase of Escherichia coli; Cribbs RM et al.; A suppressor mutation specific for a missense codon in the L-ribulokinase structural gene of the L-arabinose operon of Escherichia coli B/r enhanced L-arabinose utilization by the strain containing the missense codon . Electrophoretic comparisons of the wild-type, missense, and suppressed missense L-ribulokinases indicated that the suppressor changed the structure of the missense kinase, thereby increasing its catalytic activity . Hyperinducibility imposed on an operator-distal gene by the missense codon was not affected by the suppressor mutation.

J Immunol, 1976 Feb, 116(2), 454 - 61
Cellular mechanism of endotoxin unresponsiveness in C3H/HeJ mice; Glode LM et al.; B cells from C3H/HeJ mice fail to respond to an endotoxin (LPS K235) which is mitogenic for normal mice including the closely related C3H/HeN strain . The cellular basis for this unresponsive state has been investigated . The C3H/HeJ mice have normal numbers of B cells, which are capable of normal responses to other B cell mitogens, such as polyinosinic acid (Poly I) . Addition of normal macrophages or spleen cells fails to reconstitute the normal response . Furthermore, neither macrophages nor spleen cells from the C3H/HeJ strain suppress the normal C3H/HeN spleen cells . Finally, spleen cells enriched for B cells by the removal of macrophages or T cells demonstrate the same differences in responsiveness to LPS . These results indicate that LPS unresponsiveness is a defect of the B cell itself and not due to suppressor cells or the absence of helper cells . When LPS is added to Poly I-stimulated cultures, there is additional enhancement of the response of normal C3H/HeN spleen cells . However, LPS causes a dose-dependent suppression of the Poly I response of C3H/HeJ spleen cells . This suppression is dependent on the time of addition of LPS to the Poly I-stimulated cultures . These data are interpreted as indicating that the binding of LPS to the membrane of C3H/HeJ B cells results in their inactivation or suppression, and that this is the basis of LPS unresponsiveness in this mouse strain.

J Bacteriol, 1976 Feb, 125(2), 524 - 30
Coordinated alterations in ribosomes and cytoplasmic membrane in sucrose-dependent, spectinomycin-resistant mutants of Escherichia coli; Mizuno T et al.; Alterations in cytoplasmic membrane and ribosomes from sucrose-dependent spectinomycin-resistant (Sucd-Spcr) mutants of Escherichia coli, mutants that are resistant to spectinomycin in the presence of 20% sucrose but sensitive in the absence of sucrose, were studied . The protein composition of cytoplasmic membrane was analyzed by gel electrophoresis on polyacrylamide gel containing 8 M urea and 0.5% sodium dodecyl sulfate, which assured the reproducible separation of 28 protein bands . A major protein band, I-19, was missing in all cytoplasmic membrane preparations from 10 Sucd-Spcr mutants . Besides protein I-19, proteins I-13 and I-24 were missing in some mutants . On the other hand, the protein composition of cytoplasmic membrane from a sucrose-independent spectinomycin-resistant mutant was indistinguishable from that from the wild-type strain . The polypeptide synthetic activity of ribosomes from Sucd-Spcr mutants was resistant to spectinomycin . Studies on a revertant obtained from one of these mutants without any selection for sensitivity to spectinomycin revealed that a single mutation was responsible for both the ribosomal alteration, i.e., spectinomycin resistance, and the lack of protein I-19 in the cytoplasmic membrane . Studies on a transductant obtained with a Sucd-SPcr mutant as the donor also confirmed the single-mutation concept . It was concluded that in Sucd-SPcr mutants an alteration in the ribosomes caused the deletion of protein I-19 from cytoplasmic membrane.

J Bacteriol, 1976 Feb, 125(2), 467 - 74
Mutant of Escherichia coli defective in response to colicin K and in active transport; Plate CA; A mutant of Escherichia coli has been isolated that grows poorly on succinate and exhibits a markedly reduced sensitivity to colicin K . This mutant is also deficient in the respiration-linked transport of proline and thiomethyl-beta-D-galactoside but appears normal for the adenosine triphosphate-dependent transport of glutamine and arginine . A temperature-conditional revertant of the mutant grows on succinate and is sensitive to colicin K at 27 C, but fails to grow on succinate and is insensitive to colicin K at 42 C . Proline transport in the temperature-conditional revertant is reduced at 42 C when either glucose or succinate is used as energy source . Glutamine transport, on the other hand, is normal at 42 C with glucose as energy source, but is reduced with succinate, although not to the same extent as is proline transport . The lack of growth on succinate and the deficiencies in transport at 42 C are not due to a temperature-dependent lesion in either the electron transport chain or in Ca2+, Mg2+-activated adenosine triphosphatase activity . Membrane vesicles prepared from the temperature-conditional revertant are impaired in proline transport at both 27 and 42 C . These findings suggest the existence in the cytoplasmic membrane of E . coli cells of a component, presumably protein, that is required for colicin K action and that functions in respiration-linked and, to a lesser degree, in adenosine triphosphate-dependent active transport systems . This protein may serve as the primary target of colicin K action.

Cell, 1976 Feb, 7(2), 279 - 88
Enzymatic in vitro synthesis of globin genes; Efstratiadis A et al.; Full-length, single-stranded rabbit globin cDNA, synthesized by AMV reverse transcriptase, apparently contains a small double-stranded sequence (hairpin) at the 3' terminus . This cDNA can serve as template-primer for E . coli DNA polymerase I, which synthesizes a strand complementary to the cDNA and covalently bound to it . The loop connecting the two strands can be cut by S1 nuclease . Reassociation, hybridization, and restriction endonuclease studies, as well as electrophoretic analyses, indicate that the sequential actions of reverse transcriptase, DNA polymerase 1, and S1 nuclease generate full-length, double-stranded synthetic globin genes.

Acta Virol, 1976 Feb, 20(1), 86 - 8
Consumption of complement in chelated and nonchelated guinea pig serum after challenge with some viral and nonviral interferon inducers; Rathova V et al.; The consumption of complement observed during the induction of interferon by various inducers may proceed via the alternate pathway . The alternate pathway requires the presence of Mg ions in the medium while Ca ions may be absent.

Proc Natl Acad Sci U S A, 1976 Feb, 73(2), 476 - 80
Mechanistic studies of glutamine synthetase from Escherichia coli: kinetic evidence for two reaction intermediates in biosynthetic reaction; Rhee SG et al.; Fast reaction techniques were used to study the kinetics of protein fluorescence intensity changes that are associated with the reactions of unadenylylated Escherichia coli glutamine synthetase {L-glutamate: ammonia ligase (ADP-forming), EC 6.3.1.2} with its substrates . It was established that the synthesis of glutamine occurs by a stepwise mechanism . During the catalytic process two fluorometrically distinct intermediates were observed . Both forward and reverse rate constants which lead to the formation and consumption of these intermediates were evaluated . The catalytic rate constant, kc, which was calculated from these rate constants agrees well with the values of kc which were determined by direct measurement of the overall biosynthetic activities by means of stopped-flow technique or the steady-state assay method.

Nature, 1976 Jan 29, 259(5541), 285 - 90
Replication control in a composite plasmid constructed by in vitro linkage of two distinct replicons; Cabello F et al.; Although it carries two competent replication systems, a composite plasmid formed in vitro by linkage of the complete ColE1 and pSC101 plasmid replicons at their unique EcoRI endonuclease cleavage sites normally uses only the replication origin and functions of the ColE1 component . Restriction of ColE1 replication functions by DNA polymerase I deprivation results, however, in exclusive use of the pSC101 replication origin . When using the ColE1 replication system the composite plasmid is nevertheless incompatible with both the parent replicons . This suggests that a trans-dominant gene product is involved in plasmid incompatibility and supports negative control rather than positive control models for regulation of the initiation of DNA replication.

Biochemistry, 1976 Jan 27, 15(2), 271 - 6
Replacement of metal in metalloenzymes . A lead-alkaline phosphatase; Sabbioni E et al.; Lead ions can interact with calf intestine alkaline phosphatase . Experiments using 203Pb-labeled Pb2+ ions showed that Pb2+ ions bind the native protein in a molar ratio of Pb/protein of 1:5 with moderate inhibition of its biochemical activity . The 4 g-atoms of Zn per mol present in the native enzyme may be removed by dialysis against EDTA . The inactive apoenzyme is capable of incorporating Pb2+ ions in a Pb/protein molar ratio of 2:1, giving a lead-protein complex still enzymatically active also when genetic material, such as nucleotides or DNA, has been used a a substrate . The reconstituted lead-protein is capable of binding Zn2+ ions without any release of the Pb2+ ions and with an increase in the catalytic activity of only 10-15% . The absence of Zn in the inactive apoenzyme as well as in the reconstituted lead-protein, the incorporation of Pb2+ ions in stoichiometric amounts in the apoenzyme, and the weak influence of the Zn2+ ions on the enzymatic assay of the lead-enzyme suggest that lead ions partially reactivate the calf intestine alkaline phosphatase apoenzyme.

Biochemistry, 1976 Jan 27, 15(2), 422 - 5
Renaturation of a multisubunit multiactivity enzyme complex: recovery of phage Qbeta RNA replicase, EF-Tu, and EF-Ts activities after denaturation in urea; Blumenthal T et al.; Phage Qbeta RNA replicase consists of four nonidentical subunits three of which are required for poly(C)-directed synthesis of poly(G): a phage-coded polypeptide and the two host-supplied protein biosynthesis elongation factors EF-Tu and EF-Ts . After denaturation of the enzyme in 8 M urea, poly(G) polymerase activity can be renaturated by dilution of the denatured subunits into a high ionic strength buffer with glycerol . The renaturation reaction has a broad temperature optimum between 11 and 21 degrees . The extent of renaturation is dependent on enzyme concentration: at low enzyme concentrations and 21 degrees renaturation proceeds for more than 3 h with greater than 40% recovery of activity, whereas at high enzyme concentrations the reaction is complete by 1 h with less than 10% of the poly(G) polymerase activity regained . Activities catalyzed by the elongation factors can be measured while they are part of the replicase complex . Study of rates of renaturation of EF-Tu and EF-Ts dependent activities alone and in the replicase complex revealed that virtually 100% of the EF-Ts activity was recovered more rapidly than could be assayed at temperatures as low as 2 degrees, while the rate of recovery of EF-Tu activity was comparable to that of the poly(G) polymerase activity and was independent of either EF-Tu concentration or the presence of other enzyme subunits . The rate of recovery of the poly(G) polymerase activity was found to be limited by the renaturation of EF-Tu, since the rate was dramatically increased by the addition of undenatured EF-Tu.

Biochemistry, 1976 Jan 27, 15(2), 328 - 34
Randomization of membrane lipids in relation to transport system assembly in Escherichia coli; Thilo L et al.; The distribution of newly synthesized lipid molecules in the pre-existing lipid phase of the membrane was studied in whole cells of the fatty acid requiring Escheria coli strain K1062 . The fluorescence probe N-phenyl-1-naphthylamine revealed reversible lipid phase transitions in cells supplemented with cis-delta9-octadecenoate (transition temperature Tt = 14 degrees C; width of the transition deltaT = 13 degrees C) or trans-delta9-hexadecenoate (Tt = 27 degrees C; deltaT = 7 degrees C) . Cells were first grown in the presence of cis-delta9-octadecenoate at 37 degrees C and subsequently for various periods in the presence of trans-delta9-hexadecenoate at 37 or 22 degrees C, i.e . above or below the transition of the newly formed lipids . Reproducible phase transitions with single, well-defined Tt values between 14 and 27 degrees C were observed under both conditions . Beta-Galactoside transport induced in a similar experiment before or during a change in the fatty acid composition showed a single change in activation energy at a temperature close to the lipid transition temperature, Tt . Starvation of cis-delta9-octadecenoate-supplemented cells for this fatty acid led to a gradual rise in the transition temperature, due to an increase in the percentage of saturated acyl chains in the membrane lipids . It is concluded that under all conditions investigated a mixed lipid phase composed of newly synthesized and pre-existing lipid molecules is formed in the membrane . Since conserved domains of newly synthesized lipids surrounding simultaneously formed transport proteins could not be demonstrated, the results do not support a membrane assembly mechanism proposed by N . Tsukagoshi and C . F . Fox {(1973), Biochemistry 12, 2822-2829} . It rather appears that newly formed lipid molecules are continuously released from their sites of synthesis into the lipid matrix by a rapid diffusion-controlled process.

Biochemistry, 1976 Jan 27, 15(2), 311 - 7
Fluorescence energy transfer measurements between ligand binding sites of the pyruvate dehydrogenase multienzyme complex; Shepherd GB et al.; The interaction of the pyruvate dehydrogenase multienzyme complex from Escherichia coli with 8-anilino-1-naphthalenesulfonate (ANS), pyruvate, and acetyl-CoA has been investigated using equilibrium binding, steady-state fluorescence, and fluorescence lifetime measurements . The fluorescnece of ANS is greatly enhanced when bound to the enzyme complex and to the pyruvate dehydrogenase component of the complex . Approximately 22 molecules of ANS are bound to a molecule of the complex with a binding constant of 3.69 muM in 0.03 M potassium potassium phosphate (pH 7.0) . Direct and competitive binding measurements indicate that about 42 pyruvate binding sites are present per mole of enzyme complex which has been stripped of thiamine diphosphate; the number of binding sites is reduced to 28,5 in the presence of a saturating concentration of thiochrome diphosphate, a thiamine diphosphate analogue . The dissociation constant for pyruvate to the enzyme complex in the presence of thiochrome diphosphate is 308 muM in 0.02 M potassium phosphate (pH 7.0) . Pyruvate, thiochrome diphosphate, and acetyl-CoA all displace ANS from the enzyme complex . In the cases of pyruvate and thiochrome diphosphate, the concentration dependence of the displacements suggests the displacement is allosteric, while in the case of acetyl-CoA direct competition appears to be involved . GTP decreased the effect of acetyl-CoA to the enzyme complex indicate that 24-26 bound acetyl-CoA molecules per complex can be readily displaced by ANS, and the binding of acetyl-CoA to these sites displays positive cooperativity . Fluorescence energy transfer measurements between bound ANS on the pyruvate dehydrogenase enzyme and FAD on the dihydrolipoyl dehydrogenase enzyme indicate, assuming the emission and absorption dipoles are randomly oriented, that these two probes must be at least 58 A apart in the intact complex.

Biochemistry, 1976 Jan 27, 15(2), 277 - 82
The control of pyruvate kinase of Escherichia coli . Binding of substrate and allosteric effectors to the enzyme activated by fructose 1,6-bisphosphate; Waygood EB et al.; The binding of various regulatory ligands and substrates to the fructose bisphosphate activated pyruvate kinase from Escherichia coli has been studied at equilibrium . The allosteric activator, fructose bisphosphate, and the substrate phosphoenolypyruvate bind in a cooperative manner to the enzyme . There is one site for each of these ligands per monomer . In the presence of fructose bisphosphate the binding of phosphoenolpyruvate follows an absorption isotherm, i.e., all homotropic interactions of the substrate are lost . In reciprocal experiments, however, both phosphoenolpyruvate and KCl are required in order to facilitate binding of the activator . The allosteric inhibitors of pyruvate kinase, ATP, succinyl-CoA, and GTP compete on the enzyme surface with the binding of the activator, fructose bisphosphate, Inhibitor pairs such as ATP and succinyl-CoA together bring about not cooperative but only additive inhibition of the binding of the activator . The nucleotide substrate GDP and the allosteric inhibitor GTP have in contrast to the activator two seemingly noninteracting sites on each monomer . In the saturating presence of fructose bisphosphate, however, binding of GDP and possibly also of GTP occurs at only one site on each monomer . Magnesium ions inhibit binding of GDP and GTP . KCl which is an activator of the enzyme along with its analogues, such as ammonia, thallium, rubidium, etc., enhances the binding of phosphoenolpyruvate but not of the nucleotides or fructose bisphosphate . The data are analyzed on the basis of a two-site model, where the substrate and fructose bisphosphate bind to one conformation and the inhibitors to the other.

Biochemistry, 1976 Jan 27, 15(2), 261 - 71
Soluble tri- and dipeptidases in Escherichia coli K-12+; Simmonds S et al.; As part of a study of the metabolic role of peptidases in Escherichia coli K-12, cell extracts were examined for the presence of three enzymes originally identified {Sussman, A . J., and Gilvarg, C . (1970), J . Biol . Chem . 245, 6518} in extracts of the lysine auxotroph ASO13 by virtue of their activity toward lysine homopolymers . It has now been shown that the activity ascribed to a Co2+-dependent dilysine-specific enzyme is a function of the strain K-12 dipeptidase DP, a metal-dependent enzyme active toward a variety of dipeptides, and that the activity ascribed to a trilysine-specific enzyme is a function of the strain K-12 tripeptidase TP, an aminopeptidase capable of hydrolyzing substrates in the series X-Gly-Gly, X-Gly-X, and X-Leu-Gly (where X is Leu or Met) but devoid of activity toward dipeptides . The third enzyme, an oligopeptidase not previously observed in strain K-12, was found to include among its substrates not only di- and trilysine but other di- and tripeptides that are hydrolyzed by the di-and tripeptidase as well as by aminopeptidases L and AP; the aminopeptidases, however, lack activity toward di- and trilysine . The absence of oligopeptidase activity from extracts of strain AJOO5, a "PEPTIDE-DEFICIENT MUTANT" derived from strain ASO13 by Sussman and Gilvarg, has been confirmed, and strain AJOO5 has been shown to contain all the other peptidases known to be present in strain K-12 . Possible functions of the oligopeptidase are proposed on the basis of its observed activity in vitro and of the basis of its observed activity in vitro and of the differences between the growth responses of strains AJOO5 and ASO13 in various media . Some general aspects of peptide metabolism are discussed with emphasis on the use of peptidase-deficient mutants in the study of this problem, and methods that may prove helpful in the isolation of such mutants are suggested.

Biochemistry, 1976 Jan 27, 15(2), 426 - 30
Mechanism of phosphonoacetate inhibition of herpesvirus-induced DNA polymerase; Leinbach SS et al.; Phosphonoacetate was an effective inhibitor of both the Marek's disease herpesvirus- and the herpesvirus of turkey-induced DNA polymerase . Using the herpesvirus of turkey-induced DNA polymerase, phosphonoacetate inhibition studies for the DNA polymerization reaction and for the deoxyribonucleoside triphosphate-pyrophosphate exchange reaction were carried out . The results demonstrated that phosphonoacetate inhibited the polymerase by interacting with it at the pyrophosphate binding site to create an alternate reaction pathway . A detailed mechanism and rate equation for the inhibition were developed . For comparison to phosphonoacetate, pyrophosphate inhibition patterns and apparent inhibition constants were determined . Twelve analogues of phosphonoacetate were tested as inhibitors of the herpesvirus of turkey-induced DNA polymerase . At the concentrations tested, only one, 2-phosphonopropionate, was an inhibitor . The apparent inhibition constant for it was about 50 times greater than the corresponding apparent inhibition constant for phosphonoacetate . DNA polymerase alpha of duck embryo fibroblasts, the host cell for the herpesviruses, was inhibited by phosphonoacetate . The apparent inhibition constants for the alpha polymerase were about 10-20 times greater than the corresponding inhibition constants for the herpesvirus-induced DNA polymerase . Duck DNA polymerase beta, Escherichia coli DNA polymerase I, and avian myeloblastosis virus reverse transcriptase were not inhibited by phosphonoacetate.

J Biol Chem, 1976 Jan 25, 251(2), 524 - 9
Effect of estrogen on gene expression in the chick oviduct . In vitro transcription of the ovalbumin gene in chromatin; Harris SE et al.; RNA was transcribed from chromatin isolated from chick oviduct and spleen by using RNA polymerase from Escherichia coli . RNA was also transcribed from whole chick DNA using E . coli RNA polymerase . DNA complementary to ovalbumin messenger RNA (cDNAov) was then used as a hybridization probe to estimate the concentration of ovalbumin messenger RNA sequences (mRNAov) in these in vitro transcripts . Although chromatin from unstimulated chick oviduct was capable of substantial RNA synthesis, no detectable mRNAov sequences could be found in the transcript . Likewise, mRNAov sequences could not be found in RNA synthesized from spleen chromatin using E . coli RNA polymerase . However, chromatin from estrogen-stimulated chick oviducts was capable of supporting synthesis of ovalbumin mRNA . We estimate that approximately 0.01% of the RNA synthesized from estrogen-stimulated chromatin was mRNAov sequences . When RNA synthesized from chick DNA was tested with the cDNAov probe, mRNAov sequences could be detected in a concentration of approximately 10% that found in the RNA transcript from estrogen-stimulated chromatin . This was as expected if the ovalbumin gene is considered to be in the "open or derepressed" region of the estrogen-stimulated oviduct chromatin . Chromatin isolated from chicks withdrawn from hormone for 12 days was only capable of supporting mRNAov synthesis in vitro at a level of 5 to 10% of that observed in chromatin prepared from estrogen-stimulated chicks, thus indicating the requirement for estrogen to maintain the ovalbumin gene in the available or "open" state in the majority of oviduct cells . These data militate against post-transcriptional control as the primary mechanism of steroid hormone regulation of specific mRNA synthesis in the chick oviduct system, and favor primary gene derepression as the most likely mechanism for estrogen induction of ovalbumin synthesis.

J Biol Chem, 1976 Jan 25, 251(2), 329 - 33
Escherichia coli glyoxalate carboligase . Properties and reconstitution with 5-deazaFAD and 1,5-dihydrodeazaFADH2; Cromartie TH et al.; Glyoxalate carboligase (EC 4.1.1.47) has been purified to electrophoretic homogeneity from Escherichia coli . The enzyme was found to be a dimer of subunits of identical molecular weight of 68,000 . Resolution of the holoenzyme into apoenzyme and FAD led to a dissociation of the dimer into monomers . The apoenzyme could be reconsitituted to full catalytic activity with FAD or the flavin coenzyme analogue 5-deazaFAD . Reconstitution of the apoenzyme with the reduced flavin analogue 1,5-dihydro-5-deazaFADH2 led to the recovery of 50% of enzymatic activity . The reconstitution of apoglyoxalate carboligase with all three coenzymes followed Michaelis-Menten kinetics with Km values of 0.25, 0.74, and 0.72 muM for FAD deazaFAD, and deazaFADH2, respectively.

Can Med Assoc J, 1976 Jan 24, 114(2), 135 - 6
Massive pulmonary hemorrhage in neonatal infection; Yeung CY; Of 35 newborn infants who died from an infection 19 had postmortem evidence of massive pulmonary hemorrhage . All but 1 of the 19 had evidence of antimortem formation of intravascular fibrin clots in lung tissue . Seventeen infants had low platelet counts . Of the 11 infants in whom coagulation studies were done, 8 had evidence of disseminated intravascular coagulation (DIC) during life . Vasculitis in the lungs, associated with fibrin clots and hemorrhages, was detected in two infants . It is postulated that sepsis is an important cause of hemorrhage in the newborn, probably as a result of the development of DIC.

Biochim Biophys Acta, 1976 Jan 23, 422(1), 109 - 19
Kinetic studies on the reaction catalyzed by polynucleotide kinase from phage T4-infected Escherichia coli; Sano H; Kinetic properties of polynucleotide kinase (EC 2.7.1.78) isolated from Escherichia coli cells infected with phage T4 were investigated . The reaction depends on the concentration of MgATP, while free ATP or free Mg2+ have neither inhibitory nor accelerating effect . The initial reaction velocity was plotted against variable concentrations of ATP as the phosphate donor at various fixed concentrations of 5'-hydroxyl-DNA or -oligo(rA) as the phosphate acceptor in the presence or absence of products . The double reciprocal plot analysis of the data suggested that the reaction obeys the random sequential mechanism . Various constants were determined and the reaction mechanism was discussed.

Biochim Biophys Acta, 1976 Jan 21, 419(2), 261 - 70
Inactivation by detergents of the proline transport system in membrane vesicles from Escherichia coli and its reactivation by bovine serum albumin; Mizushima S; The proline transport system of membrane vesicles from Escherichia coli was inactivated by a low concentration of detergents such as deoxycholate, dodecyl sulfate and Triton X-100 . The addition of a large amount of bovine serum albumin to membrane vesicles which had been treated with one of these detergents resulted in the restoration of the proline transport activity . The restoration of the transport activity by bovine serum albumain was most remarkable with the deoxycholate-inactivated membrane vesicle . 80% inactivation of the transport system with 0.005% deoxycholate was completely overcome by the addition of albumin . The degree of restoration was dependent on the concentration of albumin . Although albumin stimulated the proline transport activity itself, the stimulatory effect could not account for the restoration of transport activity . The binding of deoxy {14C}cholate to the membrane vesicle was roughly proportional to the amount of detergent added . Deoxycholate once bound to the membrane vesicle was removed almost completely by the incubation with albumin . It is concluded that the removal of detergent from the membrane vesicle by bovine serum albumin results in the restoration of the proline transport activity.

Biochim Biophys Acta, 1976 Jan 19, 418(2), 160 - 6
The action of cordycepin on nascent nuclear RNA and poly(A) synthesis in regenerating liver; Glazer RI; Following a 5 min pulse of {5- 3H}orotic acid via the protal vein, the specific radioactivity of non-poly(A)heterogeneous nuclear RNA (HnRNA) reaches a peak at 12 h after partial hepatectomy . In contrast, poly(A)-HnRNA was maximally elevated only at 2 h after operation . After intraportal injection of cordycepin (3'-deoxyadenosine) 1 min before {5-3H}orotic acid, a dose-dependent inhibition of nuclear HnRNA and rRNA occurred . Fractionation of HnRNA on poly(U)-Sepharose following 20 mg/kg of cordycepin revealed that a 65% reduction occurred in the labeling of poly(A)-HnRNA while non-polyactivity of UTP in control and cordycepin-treated animals indicated no significant alterations in these parameters . Assessment of poly(A) size using poly(A)-HnRNA annealed with oligo(dT)10 as template primer for Escherichia coli DNA polymerase I, showed that 20 mg/kg of cordycepin inhibited nuclear polyadenylylation by 43%; no alteration in the binding of poly(A)-HnRNA to Millipore filters occurred at this dose of cordycepin . These results indicate that cordycepin is a non-selective inhibitor of nuclear RNA and poly(A)synthesis in regenerating rat liver.

Biochim Biophys Acta, 1976 Jan 19, 418(2), 204 - 16
The polypeptide chain growth rate in amino acid-starved Escherichia coli determined by a novel method; Cassada R et al.; The proteins synthesized by arginine-requiring Escherichia coli during growth or arginine starvation were characterized by polyacrylamide gel electrophoresis in sodium dodecyl sulfate to give size distributions . The proteins made during amino acid starvation were smaller than those made by growing cells . This was true for otherwise isogenic rel- ("relaxed") and rel+ ("stringent") bacteria . Also using electrophoretic profiles, the peptide chain growth rate was estimated by a novel method based on comparison of theoretically predicted and observed kinetics of pulse labeling protein chains of different sizes . During arginine starvation, the rate was 2--5 amino acids/s for both rel- and rel+ cells, compared to 20 amino acids/s for growing cells . The results rule out chain growth-rate differences as an aspect of the "relaxed" phenomenon.

Biochim Biophys Acta, 1976 Jan 19, 418(2), 137 - 45
The binding of near-ultraviolet light-induced tryptophan photoproduct(s) to DNA; Glatzer L et al.; To test one possible mode of toxicity of L-tryptophan photoproduct(s) to bacterial cells, we have examined the binding of near-ultraviolet light-treated tryptophan to purified Escherichia coli DNA in vitro . The results show that co-irradiated (or pre-irradiated) {3H}tryptophan binds to purified DNA as assayed by trichloroacetic acid co-precipitation of DNA and 3H counts on cellulose filters . This was supported by co-sedimentation of DNA and 3H photoproduct(s) on CsCl gradients . Hot trichloroacetic acid extraction or enzymatic digestion of DNA prevents filter binding . The binding is most efficient when tryptophan and DNA are co-irradiated . Under these conditions, binding is more efficient with denatured rather than native DNA . From kinetic studies, the binding is DNA-dependent at constant doses of near-ultraviolet light . At a dose of 2.16 - 10(6) ergs - mm-2 we estimate that 100-150 L-{3H}tryptophan equivalents are bound per E . coli genome equivalent . The binding does not occur with another aromatic amino acid such as tyrosine.

Biochim Biophys Acta, 1976 Jan 18, 486(1), 47 - 54
Studies on the biosynthesis of acylphosphatidylglycerol in Escherichia coli B and B/r; Cho KS et al.; The present study has demonstrated that one molecule of acylphosphatidylglycerol was synthesized from two molecules of phosphatidylgycerol by the transacylation reaction in which phosphatidylglycerol acted both as an acyl donor and an acceptor . Phosphatidylethanolamine was identified as an another acyl donor, participating in acylphosphatidylglycerol formation . These results are discussed in terms of a new pathway for the turnover of phosphatidylglycerol in Escherichia coli.

Mol Gen Genet, 1976 Jan 16, 143(2), 223 - 32
Isolation of rec- mutants from an F-prime merodiploid strain of Escherichia coli K-12; Stacey KA et al.; This paper describes a method of screening mutagenised populations of an E . coli galA/galB F- prime merodiploid for mutants defective in recombination . The method relies on scoring colonies on Eosin-Methylene Blue agar that have fewer than normal numbers of Gal+ papillae . With a suitable choice of gal- mutations most of the papillae arise by recombination and some of those colonies with less than normal numbers prove to be defective in some aspect of recombination or DNA repair . In addition to strains carrying mutations that can be ascribed to known loci, several novel mutant phenotypes were identified.

Mol Gen Genet, 1976 Jan 16, 143(2), 211 - 21
Isolation and genetic characterization of the nitA mutants of Escherichia coli affecting the termination factor rho; Inoko H et al.; Taking advantage of the Spi (sensitivity to P2 interference) phenomenon, bacterial mutants seemingly resistant to phage lambdasusNnin5, but sensitive to phage lambdaspi, were isolated from a strain of E . coli K12 carrying no nonsense suppressor and lysogenic for P2 . A class of these mutants, designated nitA (N-independent transcription), is described here . Upon infection of the nitA mutants with a trp transducing phage lambdasusN7N53ptrp46 which carries the E . coli trpE and D genes in the CIII-att region of the lambda genome, formation of anthranilate synthetase (ASase, a complex protein of trp E and D gene products) was clearly demonstrated . In contrast, no ASase formation was observed in the parent nitA+ strain under the same conditions . The synthesis is subject to "turn off" control, and is completely repressed by the CI repressor of phage lambda . The nitA cells lysogenic for lambdaCI857susN7N53 are killed by thermal induction much more efficiently than the parent cells lysogenic for the same phage . The nitA mutants support the growth of lambdasusN7N53byp much better than the parent . These results suggest that the nitA mutation permits the early leftward and rightward transcription of the lambda genome in the absence of the N gene product . On the E . coli genetic map, nitA is located between ilv and metE, nearer to ilv . The mutant allele is recessive to the wild-type allele . The present evidence, together with results of biochemical investigations to be reported, suggests that nitA is a gene specifying the transcription termination factor rho.

Eur J Biochem, 1976 Jan 15, 61(2), 563 - 72
Action of nucleases on double-stranded RNA; Edy VG et al.; Double-stranded RNAs from Penicillium chrysogenum virus have been treated with RNAse III, pancreatic RNAse A and RNAse T1 and the degradation of the RNAs has been studied under different conditions . It was found that only the two former enzymes cut across both strands, RNase T1 cannot cleave double strands . RNase III was shown to digest double-stranded RNA by a two step process: an initial phase of specific cleavage is followed by random degradation . In the first phase the enzyme exhibited a definite preference for some specific base pattern . Partial or complete degradation with pancreatic RNase A could also be achieved in media with high salt concentration provided that the enzyme: substrate ratio was increased together with the salt concentration . By combining different assay techniques, the process of degradation was followed from the early stages to complete digestion and the breakdown products were characterised . It is suggested that a structural change in the enzyme molecules enables them to act on double-stranded RNA . RNAse T1, being unable to cleave double strands, provides a useful tool for studying the secondary structure of RNA molecules . Treatment with different nucleases yielded some new information on the structure of different RNA species in Penicillium stoloniferum virus.

Biochem J, 1976 Jan 15, 154(1), 239 - 41
Membrane attachment of folded chromosome of Escherichia coli; Dworsky P; By fractionation of the envelope part of membrane-associated folded chromosomes it is shown that only the outer membrane is bound to the DNA . Experiments with the M-band technique suggest the presence of attachment points for the membrane also in membrane-released folded chromosomes.

Eur J Biochem, 1976 Jan 15, 61(2), 501 - 13
Carcinogen-induced DNA repair in nucleotide-permeable Escherichia coli cells . Analysis of DNA repair induced by the carcinogens N-acetoxy-N-2-acetylaminofluorene and 7-bromomethyl-benz(a)anthracene; Thielmann HW; Upon exposure to the carcinogens N-acetoxy-N-2-acetylaminofluorene and 7-bromomethyl-benz{a}anthracene, which bind covalently to DNA, ether-permeabilized (nucleotide-permeable) Escherichia coli wild-type cells responded with DNA excision repair . This repair was missing in mutants carrying defects in genes uvrA, uvrB and uvrC, whereas it was present in uvrD and several rec mutants . Enzymic activities involved were identified by measuring repair polymerization and size reduction of denatured DNA . 1 . An easily measurable effect in E . coli wild-type cells was carcinogen-induced repair polymerization . When initiated by N-acetoxy-N-2-acetylaminofluorene or 7-bromomethyl-benz{a}anthracene, it depended upon an ATP-requiring step; CTP, GTP or UTP did not substitute for ATP . DNA repair synthesis was inhibited by p-chloromercuribenzoate and quinacrine . In uvrA, uvrB and uvrC mutants no carcinogen-stimulated DNA synthesis could be detected, indicating that steps involved in pyrimidine dimer excision are also involved in chemorepair . In recA, recB and recC mutant cells, repair synthesis was stimulated by the carcinogens to a normal extent . This evidence excludes the ATP-dependent recB,C deoxyribonuclease and recA gene products as playing an important role in carcinogen-induced excision repair . polA1 cells showed drastically reduced levels of rapair polymerization, indicating that DNA polymerase I is the main polymerizing enzyme . 2 . As determined by DNA size reduction in alkaline sucrose gradients, the arylalkylating carcinogens caused endonucleolytic cleavage of endogenous DNA in wild-type cells . This incision step was most effectively performed in the presence of ATP; UTP, CTP and GTP were only slightly effective . Incision was inhibited by p-chloromercuribenzoate and quinacrine . When exposed to the arylalkylating carcinogens, uvrA, uvrB and uvrC mutant cells did not perform the incision step in the presence of ATP, suggesting the involvement of the respective gene products in the initiation of chemorepair.

Eur J Biochem, 1976 Jan 15, 61(2), 433 - 42
Processing of the 17-S Escherichia coli precursor RNA in the 27-S pre-ribosomal particle; Hayes F et al.; An RNase activity probably involved in the maturation of 16-S pre-ribosomal RNA in Escherichia coli has been partially purified from crude cell extracts . When 27-S ribosome precursor particles are incubated with this enzyme preparation in vitro, their 17-S RNA is converted to a product with the same electrophoretic mobility as mature 16-S rRNA . Fingerprint analysis of this product shows that it contains the 3'-OH but not the 5'-P terminus of mature 16-S rRNA . Generation of the normal 5'-P terminus seems to require a factor present in cell extracts since incubation of the 27-S precursor particle in an extract obtained after centrifugation at 30 000 x g causes conversion of the 17-S RNA to a 16-S species containing both termini of mature 16-S rRNA . Preliminary experiments suggest that correct maturation of the 5' end of the 17-S precursor RNA requires a system in which protein synthesis can take place.

Eur J Biochem, 1976 Jan 15, 61(2), 597 - 603
The purification and properties of the trimethoprim-resistant dihydrofolate reductase mediated by the R-factor, R388; Amyes SG et al.; The R-factor R388 mediates the production of a trimethoprim-resistant dihydrofolate reductase . This enzyme has a different molecular weight and pH profile to the trimethoprim-sensitive enzyme of the Escherichia coli host . The R-factor mediated enzyme was separated completely from the host E . coli enzyme by DEAE-cellulose ion-exchange chromatography . The purified R-factor enzyme was about 20 000 times less susceptible to trimethoprim than the E . coli enzyme and although it was inhibited competitively by trimethoprim, its inhibitor constant (Ki) was 20 000 times greater than that of the host enzyme . The R388 and E . coli enzymes also differed in their substrate specificity requirements . In addition, the R388 enzyme suprisingly conferred high level resistance to the broad spectrum dihydrofolate reductase inhibitor, amethopterin . The possible origins of the R388 enzyme are discussed.

Biochim Biophys Acta, 1976 Jan 14, 421(1), 33 - 43
The influence of glutamine, its decomposition products, and glutaminase on the transformation of human and mouse lymphocytes; Baechtel FS et al.; The extent of blast transformation for human and BALB/c mouse lymphocytes has been examined over a wide range of glutamine concentrations with several agents which initiate blastogenesis . Maximum {3H} thymidine incorporation was seen at 0.5 mM glutamine for lymphoid tissues stimulated in the following manner: human and BALB/c splenic and peripheral blood lymphocytes with phytohemagglutinin, BALB/c splenic lymphocytes with lipopolysaccharide, and BALB/c vs C3H/HeJ two-way mixed lymphocyte cultures . The inhibition of blastogenesis exerted by glutamine concentrations greater than 0.5 mM could not be reversed by washing and reculturing the cells at 0.5 mM glutamine . To elucidate the reason for inhibition by higher glutamine concentrations, the products of spontaneous glutamine decomposition, L-2-pyrrolidone-5-carboxylic acid and ammonia were tested for their in vitro influence on BALB/c splenocyte blastogenesis . Pyrrolidone-carboxylic acid, in concentrations up to 5 mM, was without effect . In contrast, ammonia concentrations exceeding 1 mM became increasingly more inhibitory . The genesis of inhibitory levels of ammonia in culture medium was confirmed and has been considered as primarily responsible for inhibiton by high glutamine . Addition of Escherichia coli glutaminase (pH optimum 4.9) to cultures of BALB/c splenocytes or human peripheral blood lymphocytes had no effect on either the extent of blastogenesis of these tissues or the glutamine levels in their culture medium.

Biochemistry, 1976 Jan 13, 15(1), 160 - 8
Conformational changes of transfer RNA . The role of magnesium(II); Stein A et al.; Magnesium ions added to tRNAfMET1 selectively stabilize the dihydrouridine helix-tertiary structural region . Low Mg2+ levels have little direct effect on the remaining three cloverleaf helices, but these are prevented from melting independently when their intrinsic Tm is surpassed by the Tm of the tertiary structure . At high Mg2+ concentration the thermal unfolding of tRNAfMet1 is approximately a two-state, concerted transition from the globular native structure to the random coil, in contrast to the sequential unfolding observed without Mg2+ . We interpret the kinetics of refolding to mean that the D helix serves as a required nucleus for the rate-limiting step of tertiary structure formation . We found that unfolding of the tertiary structure leads to loss of the tightly bound Mg2+ ions, and showed with a Mn2+-sensitive fluorescent indicator that the rate of Mn2+ release is the same as the rate of unfolding the tertiary structure . Hence the tightly bound divalent ion must be located in a site formed by the tertiary structure-D helix region of the molecule.

Biochemistry, 1976 Jan 13, 15(1), 157 - 60
Equilibrium binding of magnesium(II) by Escherichia coli tRNAfMet; Stein A et al.; Equilibrium dialysis measurements show that tRNAfMet1 in 0.17 M Na+ has one strong Mg2+ binding site, K = 3 X 10(4) M-1, and approximately 26 weak binding sites with K = 4 X 10(2) M-1, with RNA concentration measured in moles of tRNA per liter and T = 4 degrees C . The data fit significantly less well to a model with two strong sites and a large class of weak sites . Binding is noncooperative . Our results differ from previous experiments showing cooperative binding because the binding equilibrium is not coupled to a cooperative conformational change of the macromolecule . Measurements at relatively high Na+ concentrations and low temperature ensure that the tRNA is in the "native" region of the conformational phase diagram for all Mg2+ concentrations.

Biochemistry, 1976 Jan 13, 15(1), 208 - 16
ATPase of Escherichia coli: purification, dissociation, and reconstitution of the active complex from the isolated subunits; Vogel G et al.; A simple procedure for the purification of Mg2+-stimulated ATPase of Escherichia coli by fractionation with poly(ethylene glycols) and gel filtration is described . The enzyme restores ATPase-linked reactions to membrane preparations lacking these activities . Five different polypeptides (alpha, beta, gamma, delta, epsilon) are observed in sodium dodecyl sulfate electrophoresis . Freezing in salt solutions splits the enzyme complex into subunits which do not possess any catalytic activity . The presence of different subunits is confirmed by electrophoretic and immunological methods . The active enzyme complex can be reconstituted by decreasing the ionic strength in the dissociated sample . Temperature, pH, protein concentration, and the presence of substrate are each important determinants of the rate and extent of reconstitution . The dissociated enzyme has been separated by ion-exchange chromatography into two major fragments . Fragment IA has a molecular weight of about 100000 and contains the alpha, gamma, and epsilon polypeptides . The minor fragment, IB, has about the same molecular weight but contains, besides alpha, gamma, and epsilon, the delta polypeptide . Fragment II, with a molecular weight of about 52000, appears to be identical with the beta polypeptide . ATPase activity can be reconstituted from fragments IA and II, whereas the capacity of the ATPase to drive energy-dependent processes in depleted membrane vesicles is only restored after incubation of these two fractions with fraction IB, which contains the delta subunit.

Biochemistry, 1976 Jan 13, 15(1), 108 - 14
The binding of reduced nicotinamide adenine dinucleotide to citrate synthase of Escherichia coli K12; Duckworth HW et al.; Citrate synthase from Escherichia coli enhances the fluorescence of its allosteric inhibitor, NADH, and shifts the peak of emission of the coenzyme from 457 to 428 nm . These effects have been used to measure the binding of NADH to this enzyme under various conditions . The dissociation constant for the NADH-citrate synthase complex is about 0.28 muM at pH 6.2, but increases toward alkaline pH as if binding depends on protonation of a group with a pKa of about 7.05 . Over the pH range 6.2-8.7, the number of binding sites decreases from about 0.65 to about 0.25 per citrate synthase subunit . The midpoint of this transition is at about pH 7.7, and it may be one reflection of the partial depolymerization of the enzyme which is known to occur in this pH range . A gel filtration method has been used to verify that the fluorescence enhancement technique accurately reveals all of the NADH molecules bound to the enzyme in the concentration range of interest . NAD+ and NADP+ were weak competitive inhibitors of NADH binding at pH 7.8 (Ki values greater than 1 mM), but stronger inhibition was shown by 5'-AMP and 3'-AMP, with Ki values of 83 +/- 5 and 65 +/- 4 muM, respectively . Acetyl-CoA, one of the substrates, and KCl, an activator, also inhibit the binding in a weakly cooperative manner . All of these effects are consistent with kinetic observations on this system . We interpret our results in terms of two types of binding site for nucleotides on citrate synthase: an active site which binds acetyl-CoA, the substrate, or its analogue 3'-AMP; and an allosteric site which binds NADH or its analogue 5'-AMP and has a lesser affinity for other nicotinamide adenine dinucloetides . When the active site is occupied, we propose that NADH cannot bind to the allosteric site, but 5'-AMP can; conversely, when NADH is the in the allosteric site, the active site cannot be occupied . In addition to these two classes of sites, there must be points for interaction with KCl and other salts . Oxaloacetate, the second substrate, and alpha-ketoglutarate, an inhibitor whose mode of action is believed to be allosteric, have no effect on NADH binding to citrate synthase at pH 7.8 . When NADH is bound to citrate synthase, it quenches the intrinsic tryptophan fluorescence of the enzyme . The amount of quenching is proportional to the amount of NADH bound, at least up to a binding ratio of 0.50 NADH per enzyme subunit . This amount of binding leads to the quenching of 53 +/- 5% of the enzyme fluorescence, which means that one NADH molecule can quench all the intrinsic fluorescence of the subunit to which it binds.

Am J Vet Res, 1976 Jan, 37(1), 15 - 24
Pathogenesis of edema disease in swine: pathologic effects of hemolysin, autolysate, and endotoxin of Escherichia coli (O141); Kurtz HJ et al.; Hemolysin, cell-free autolysate, and lipopolysaccharide (LPS) prepared from Escherichia coli (O141) were parenterally administered to 113 weaned pigs . Both the hemolysin and the cell-free autolysate were crude preparations which probably contained several biologically active substances . Pigs in all groups which die less than 72 hours after injection had similar gross and microscopic lesions . The pigs which survived (chronically affected pigs) were killed 3 to 12 days after injection . Of the pigs that lived more than 72 hours after injection, those given hemolysin and autolysate had generalized vascular myolysis and fibrinoid necrosis, whereas those given LPS had morphologically normal blood vessels . The vascular changes produced by hemolysin and autolysates of E coli (O141) were the same as the histologic angiopathy of naturally occurring edema disease of pigs . The LPS produced acute lesions of endotoxin shock in the pigs, but did not produce the angiopathy characteristic of edema disease . Typical clinical signs of naturally occurring edema disease were not a consistent observation in any of the treatment groups.

J Biol Chem, 1976 Jan 10, 251(1), 241 - 6
Studies on arginyl-tRNA synthetase from Escherichia coli B . Dual role of metals in enzyme catalysis; Craine JE et al.; Studies carried out in arginyl-tRNA synthetase from Escherichia coli indicate that metals may have two functional roles in the catalytic mechanism . Complete metal activation is observed when MgCl2, MnCl2, CoCl2, or FeCl2 is present at a concentration (5.0 mM) in excess of the total ATP concentration (2.0 mM) . When CaCl2 is substituted for MgCl2, activity is not observed unless a small amount (0.1 mM) of MgCl2, MnCl2, CoCl2, FeCl2, or ZnCl2 (unable to produce activity alone at 5.0 mM) is added . A model, based on kinetic data, is proposed in which the enzyme possesses a site for free metal, which, when filled, lowers the Km for all three substrates (arginine, tRNAArg, and metal-ATP) and increases the Vmax of the reaction.

N Engl J Med, 1976 Jan 8, 294(2), 75 - 80
Reverse transcriptase in leukocytes of leukemic patients in remission; Viola MV et al.; A cytoplasmic particulate fraction from human leukemic cells has been shown to contain reverse transcriptase and its associated high-molecular weight RHA template . We attempted to detect the reverse-transcriptase-template complex in morphologically normal peripheral blood leukocytes from patients with acute leukemia in complete remission . Our assay system consisted of a velocity glycerol gradient and cesium sulfate equilibrium gradient analysis of the endogenous reverse transcriptase reaction product . Three of nine patients in remission had positive reactions determined by glycerol gradient analysis, and eight of 10 patients in remission had positive reactions by cesium sulfate gradient analysis . We were unable to detect the template complex in leukocytes of normal persons . Thus, normal-appearing leukocytes in the peripheral blood of some leukemia patients in remission seem to retain a number of biochemical characteristics, possibly viral related, associated with leukemic cells.

Biochim Biophys Acta, 1976 Jan 5, 418(1), 133 - 6
Apparent thermal destabilization of Escherichia coli nucleoprotein due to the incomplete dialysis of EDTA; Searcy DG et al.; Escherichia coli nucleoprotein has been found to undergo thermal denaturation approx . 5 degrees C lower than purified E . coli DNA, measured in 0.25 mM sodium EDTA, pH 8.0 (Searcy, D.G . (1975) Biochim . Biophys . Acta 395, 535-547) . This is now shown to be an artifact due to the impermeability of dialysis membranes to sodium EDTA, especially at low concentrations such as 1 mM or less . Thermal denaturation data can be corrected by measuring the electrical conductivity of the solutions . When this is done, the nucleoprotein and DNA both denature at the same temperature.

Eur J Biochem, 1976 Jan 2, 61(1), 81 - 91
Studies of intracellular thymidine nucleotides . Relationship between the synthesis of deoxyribonucleic acid and the thymidine triphosphate pool in Escherichia coli K12; Ohkawa T; The two types of mutant strains which show resistance to T-even phage infection have been isolated and been shown to have either a higher or lower ratio of dTDP-sugar to dTTP than that of the parent strains . The one with a higher ratio of dTDP-sugar to dTTP than the parents has a large dTDP-sugar pool and small dTTP pool, and a high level of dTDPG pyrophosphorylase activity . The other one, with a lower ratio of dTDP-sugar to dTTP than the parents, has a small dTDP-sugar pool and large dTTP pool, and a low or deficient level of this enzyme activity . They form an entirely mucoid colony in the synthetic agar plate . Mutant cells (Ter-6 and Ter-21) which have deficient dTDPG pyrophosphorylase activity show 2 -- 3 times higher activity of UDPG pyrophosphoyrlase than that of parent cells . The dTDPG pyrophosphorylase-deficient mutants (Ter-15 and Ter-21) have a 3 -- 4 times higher concentration of dTTP and a faster rate of DNA synthesis and cell division than those of parent strains in growth with external thymine . The dTDPG pyrophosphorylase constitutive mutant (Ter-4) has a 0.5 -- 0.33 smaller dTTP pool and a slower rate of DNA synthesis and cell division than those of parent cells grown in the same medium . In the Ter-15 and Ter-21 mutants, the intracellular dTTP-dependent DNA synthesis rapidly disappeared in thymine suboptimal concentration, but the Ter-4 mutant maintained its dTTP-dependent DNA synthesis over a 20 muM concentration of external thymine . In high concentration (100 muM) of external thymidine, the thymidine effects on the intracellular dTTP concentration do not significantly appear in these enzyme-deficient mutants (Ter-15 and Ter-21) . Also, the concentration of intracellular dTTP in the cell growth with external thymidine is 2.5 times greater than that with external thymine in these enzyme-deficient mutants (Ter-15 and Ter-21).

Eur J Biochem, 1976 Jan 2, 61(1), 307 - 15
Chemical inactivation of Escherichia coli 30-S ribosomes by iodination . Identification of proteins involved in tRNA binding; Shimizu M et al.; 30-S ribosomal subunits are inactivated by iodination for both enzymic fMet-tRNA and non-enzymic Phe-tRNA binding activities . This inactivation is due to modification of the protein moiety of the ribosome . Reconstitutions were performed with 16-S RNA and mixtures of total protein isolated from modified subunits and purified proteins isolated from unmodified subunits . This allowed identification of the individual proteins which restore tRNA binding activity . S3, S14 and S19 were identified as proteins involved in fMet-tRNA binding . S1, S2, S3, S14 and S19 were identified as proteins involved in Phe-tRNA binding . Modified particles shown normal sedimentation constants and complete protein compositions both before and after reconstitution . This suggests that the loss of activity is due to modification of one or more of the actual binding sites located on the 30-S subunit and that restoration of activity is due to structural correction at this site rather than to correction of an assembly defect.

Eur J Biochem, 1976 Jan 2, 61(1), 317 - 23
Activity of the 30-S CsCl core in elongation-factor-dependent GTP hydrolysis; Sander G et al.; The activity of a 30-S CsCl core lacking proteins S1, S2, S3, S5, S9, S10, S14, S20 and S21 has been studied in the ribosome-dependent FTPase reactions in the presence of the 50-S subunit with and without methanol . Without methanol, the 30-S CsCl core was unable to sustain GTPase activity dependent on elongation factor G (EF-G), while it was only slightly active in the presence of elongation factor T (EF-T) . With EF-T, addition of methanol induced in the presence of either 30-S subunits or 30-S CsCl cores an activity which was more than 10-fold higher than that observed with the 30-S subunit in the absence of methanol . Methanol lowered the Mg2+ optimum of the EF-T-dependent GTPase reaction from approximately 20 mM to approximately 10 mM . In the absence of methanol the EF-G-dependent (GTPase reaction at low concentration of monovalent cations depends on the 50-S subunit alone (30-S-uncoupled EF-G GTPase) . Addition of the intact 30-S subunit but not of its CsCl core abolished inhibition of the 30-S-uncoupled EF-G-GTPase by NH4+ . The 30-S CsCl core caused the same effect as the 30-S subunit when methanol was present . 30-S-uncoupled EF-G GTPase activity was lower than the GTPase activity dependent on 30-S plus 50-S subunits at {EF-G}/{50-S} below 5 but was considerably higher in the presence of a large excess of EF-G . In the presence of methanol the 30-S CsCl core behaved similarly to the 30-S subunit . Our results indicate that the action of the 30-S subunit in elongation-factor-dependent GTPases is supported by structural features that are preserved in the 30-S CsCl core . The 30-S split proteins are therefore not essential for EF-G and EF-T activities in the hydrolysis of GTP . With EF-T, in all conditions tested association of the ribosomal subunits appeared to accompany GTPase activity . Association seems also to be a prerequisite of the EF-G GTPase activity that depends on both ribosomal subunits.

Biochimie, 1976, 58(3), 253 - 9
{Phenylalanyl-tRNA synthetase of wheat embryos . Purification, molecular weight, structure, properties}; Carias JR et al.; From wheat germ, a phenylalanyl-tRNA synthetase (E.C.6.1.1.20) has been isolated and purified 187 fold by means of ammonium sulfate fractionation (40-50 per cent) followed by Sephadex G-200 gel filtration, chromatographies on DEAE-cellulose and hydroxyapatite . The enzyme appears to be homogeneous on Sephadex G-200 molecular filtration and polyacrylamide gel electrophoresis . Molecular weight determinations by sucrose gradient centrifugation, gel filtration and gel electrophoresis give an average of 250 00 daltons . The enzyme is dissociated in 1 per cent sodium dodecyl sulfate into two different equimolar components of 80 000 and 50 000 daltons ; this result suggests that the phenylalanyl-tRNA synthetase has a subunit structure : alpha2 beta2 . Dissociation with sodium dodecyl sulfate and dithiothreitol gives four other components, probably resulting from the breakdown of the subunits . Optima values of pH, Mg2+ and K+ concentrations, effect of SH-compnents, kinetic parameters have been determined in the aminoacylation reaction . Physical and catalytic properties of wheat germ phenylalanyl-tRNA synthetase appear very similar to those of the yeast and E . coli enzymes.

Gerontology, 1976, 22(3), 111 - 23
Influenza of age on chromatin transcription in murine tissues using a heterologous and an homologous RNA polymerase; Hill BT; No gross changes in the compositions of chromatin prepared from liver, kidney and brain were noted with age . A decreased age-dependent in vitro chromatin template activity was observed using an Escherichia coli RNA polymerase . This was paralleled by a reduction in the number of initiation sites on the chromatin for the enzyme . However, using a homologous RNA polymerase definite age-related specificities in template activity were found . When chromatin and enzyme were 'age-matched', maximal activity was observed . This levle of activity was comparable in both 6 and 31-month-old mice, which suggested no impairment of function with age.

J Clin Microbiol, 1976 Jan, 3(1), 21 - 5
Preparation and properties of a national reference endotoxin; Rudbach JA et al.; A large pool of refined endotoxin was prepared from Escherichia coli O113 by extraction with hot acqueous phenol . It was characterized chemically and biologically and will be available for a reference standard designated as reference endotoxin EC.

Nucleic Acids Res, 1976 Jan, 3(1), 177 - 90
The use of a dipolar ion-exchanger for the fractionation of transfer ribonucleic acid; Jay FT et al.; Transfer ribonucleic acid is well fractionated on columns of arginine-agarose, whose properties appear in general to be similar to those of DEAE-Sephadex . However, the amino acid acceptor species are separated into sharper peaks and in several instances, notably for methionine, glycine, serine, leucine and aspartate accepting tRNAs from Escherichia coli, isoaccepting species are well resolved . In the case of methionine accepting tRNA from E . coli the tRNA Met-m species is eluted before the tRNA Met-f species and since it is also eluted prior to the bulk of the tRNA it is obtained in a high degree of purity . By comparing the properties of columns of arginine-agarose and its methyl ester in which the carboxylate anion is blocked, it is seen that the carboxylate ion plays a role in the fractionation of the tRNA Met species.

Proc Natl Acad Sci U S A, 1976 Jan, 73(1), 91 - 4
Chemical and enzymatic synthesis of lactose operator of Escherichia coli and its binding to lactose repressor; Bahl CP et al.; The 21-nucleotide-long duplex DNA constituting the lactose operator sequence of E . coli has been synthesized by both chemical and enzymatic methods . The synthetic duplex has the essential feature of the lactose operator as seen by its binding to the lactose repressor . The binding of the synthetic operator fragment to the lactose repressor is specific because it is inhibited by the inducing ligand isopropyl-beta-D-thiogalactoside . Thus, it is now possible to show that a chemically synthesized oligodeoxynucleotide can be specifically recognized by its natural regulatory protein.

Proc Natl Acad Sci U S A, 1976 Jan, 73(1), 86 - 90
Incorporation of fatty acids containing photosensitive groups into phospholipids of Escherichia coli; Greenberg GR et al.; A series of new fatty acids containing photosensitive groups at different positions on the paraffin chains supported the growth of an auxotroph of E . coli requiring unsaturated fatty acids . The derivatives were 6-, 9-, 11-, and 12-azidostearic acids, 12-azido-oleic acid, 16-azidopalmitelaidic acid, and 12-(4-azido-2-nitrophenoxy)-stearic and -oleic acids . Analyses of the phospholipids from cultures grown in the presence of the first six compounds showed that these derivatives accounted for 16-43% of the total fatty acids . Further analysis of phospholipids from cultures grown with 12-azido-oleic acid, 11-azidostearic acid, or 16-azidopalmitelaidic acid indicated that the azido fatty acids were at the 2-position of the glycerol moieties . The incorporation of these fatty acid derivatives offers a new approach to the study of membrane structure and, in particular, phospholipid-protein interactions by photolysis-induced crosslinking of the fatty acids to the structures in their immediate vicinity.

Proc Natl Acad Sci U S A, 1976 Jan, 73(1), 64 - 8
Molecular cloning of DNA from F sex factor of Escherichia coli K-12; Skurray RA et al.; We describe the molecular cloning of various DNA segments generated by partial EcoRI endonuclease digestion of the sex factor F . These segments have been analyzed by agarose gel electrophoresis of EcoRI digests and were arranged in a series of overlapping fragments using the EcoRI fragment map of F established by H . Ohtsubo and E . Ohtsubo . The clones isolated demonstrate one or more of the following F-specified functions: inhibition of female-specific phage (T7) multiplication, formation of F pili, surface exclusion, or immunity to lethal zygosis . These properties are discussed in terms of the EcoRI fragments of F that specify them.

Proc Natl Acad Sci U S A, 1976 Jan, 73(1), 59 - 63
Mechanism of growth delay induced in Escherichia coli by near ultraviolet radiation; Ramabhadran TV et al.; Continuously growing cultures of E . coli B/r were irradiated with a fluence of broad-band near-ultraviolet radiation (315-405 nm) sufficient to cause extensive growth delay and complete cessation of net RNA synthesis . Chloramphenicol treatment was found to stimulate resumption of RNA synthesis, similar to that observed with chloramphenicol treatment after amino-acid starvation . E . coli strains in which amino-acid starvation does not result in cessation of RNA synthesis ("relaxed" or rel- strains) show no cessation of growth and only a slight effect on the rate of growth or of RNA synthesis . These findings show that such near-UV fluences do not inactivate the RNA synthetic machinery but affect the regulation of RNA synthesis, in a manner similat to that produced by amino-acid starvation . Such regulation is believed to be mediated through alterations in concentration of guanosine tetraphosphate (ppGpp), and our estimations of ppGpp after near-UV irradiation are consistent with such an interpretation . These data, combined with earlier published data, strongly suggest that the mechanism of near-UV-induced growth delay in E . coli involves partial inactivation of certain tRNA species, which is interpreted by the cell in a manner similar to that of amino-acid starvation, causing a rise in ppGpp levels, a shut-off of net RNA synthesis, and the induction of a growth delay.

Proc Natl Acad Sci U S A, 1976 Jan, 73(1), 198 - 202
Novel F prime factors able to replicate in Escherichia coli Hfr strains; Hiraga S; A novel type of F' plasmid that can replicate extrachromosomally in cells of Hfr strains has been isolated . Genetic analysis of these plasmids indicates that all carry the dnaA-bglA region of the E . coli chromosome as well as ilv+ used as a selective marker . It is suggested that a specific site, designated poh+ (permissive on Hfr), is located in this region, and is essential for these plasmids to replicate in Hfr cells . The most interesting explanation, among others, would be that the poh+ site represents the replication origin of the bacterial chromosome.

Obstet Gynecol, 1976 Jan, 47(1), 56 - 62
Antenatal infection: adequate protection against hyaline membrane disease?
Dimmick J, Mahmood K, Altshuler G.
It has been argued that fetal and placental infections decrease the incidence of hyaline membrane disease (HMD) . However, others contend that this is not so . We performed a rigidly controlled clinicopathologic investigation of one group of infants with evidence of severe antenatal infection compared with another group free of infection . This study shows that placental infection correlated positively with neonatal sepsis and that in this series of patients neither infection nor prolonged rupture of membranes is associated with a decrease of HMD . Our data do not support the proposal that antenatal infections protect the neonate against later development of HMD.

J Med Chem, 1976 Jan, 19(1), 71 - 98
Correlation analysis of Baker's studies on enzyme inhibition . 2 . Chymotrypsin, trypsin, thymidine phosphorylase, uridine phosphorylase, thymidylate synthetase, cytosine nucleoside deaminase, dihydrofolate reductase, malate dehydrogenase, glutamate dehydrogenase, lactate dehydrogenase, and glyceraldehyde-phosphate dehydrogenase; Yoshimoto M et al.; The inhibitory activity of 1058 inhibitors of the title enzymes has been formulated in 13 equations correlating chemical structure with inhibitory potency . Two types of regions in enzymes have been defined by means of pi and molar refractivity constants . The use of indicator variables has been extensively developed to suggest special enzyme-ligand interactions . Several examples are given of the use of correlation equations in comparing structural features of different systems.

J Gen Microbiol, 1976 Jan, 92(1), 156 - 66
Genetical and physiological studies on a thermosensitive mutant of Escherichia coli defective in cell division; Holland IB et al.; A new temperature-sensitive mutant of E . coli, defective in cell division, was isolated after selection for tolerance to colicin E2 . The mutant strain, ASHI24, growing in either minimal or complex medium, commences filament formation immediately upon shift to high temperature . High densities of bacteria or the presence of 0-44 M-sucrose prevents filament formation at 42 degrees C and division continues . Filament formation in the mutant is reversible and upon return to 29 degrees C the multinucleate filaments divide up into normal-sized bacteria by a series of rapid but sequential divisions . In the presence of chloramphenicol at 29 degrees C, 25% of these division sites are still expressed . A genetic locus designated ftsH, apparently controlling both temperature sensitivity and filament formation, was provisionally mapped at minute 80 on the E . coli K12 map.

J Gen Microbiol, 1976 Jan, 92(1), 133 - 7
Mutations in Escherichia coli that relieve catabolite repression of tryptophanase synthesis . Tryptophanase promoter-like mutations; Ward DF et al.; From a strain lacking adenyl cyclase and the catabolite-sensitive gene activator protein, two mutants were isolated that can synthesize tryptophanase . Each mutation is extremely closely linked to the tryptophanase structural gene . The mutations differ from one another in the rate of synthesis of tryptophanase that they permit in the genetic background in which they were isolated; they differ from one another and also from the wild type in the maximum rate of synthesis of tryptophanase that they permit in a genetic background with intact adenyl cyclase and catabolite-sensitive gene activator protein . Both mutations appear to lie in the tryptophanase promoter.

J Immunol, 1976 Jan, 116(1), 8 - 11
Antibody responses of mice to alkaline detoxifield lipopolysaccharide; Von Eschen KB et al.; The antibody responses of outbred normal mice and nude mice injected with alkaline detoxified lipopolysaccharide (Alk-LPS) were measured . In some cases the antibody against lipopolysaccharide (LPS) and native protoplasmic polysaccharide (NPP) . The kinetics of the primary responses to Alk-LPS and NPP were similar, whereas LPS stimulated a more rapid appearance of antibodies in the primary responses . Alk-LPS stimulated only primary antibody responses in both types of mice and sensitized nude mice for secondary responses which could be triggered with LPS . However, secondary antibody responses could not be triggered in normal mice primed with Alk-LPS . These data suggested that, on a functional basis, Alk-LPS possessed the specific antigenic signal associated with LPS antigens but lack the second nonspecific mitogenic signal dependent on the lipid A portion of LPS.

J Bacteriol, 1976 Jan, 125(1), 58 - 67
Genetic and physical studies of recombinant plasmids formed between an R plasmid of compatibility group FI and sex factor F of HfrH; Horodniceanu T et al.; Recombinant plasmids between an R plasmid of the FI group (R162/3) and the sex factor F or HfrH were produced after the conjugal transfer of this R plasmid into HfrH . Three types of recombinant plasmids were identified after the mating of HfrH (R162/3) with recA and rec+ recipients . One specimen of each type (pIP218, pIP222, pIP226) was studied in this report . All three recombinant plasmids carry the same genetic information for resistance to antibiotics (CSSuT) retained from R162/3 . pIP218 retained all the other properties from F of HfrH: derepression for pilus synthesis, mobilization of the chromosome for the proximally transferred HfrH genes (thr, leu, proA), interference with T7 propagation, and ability to be cured by acridine orange . pIP222 retained from F of HfrH the derepression for pilus synthesis and the same polarity of chromosome transfer (thr, leu, proA), while pIP226 retained the interference with T7 propagation and acridine orange curing . Physical studies revealed that replication control and/or recovery of F and pIP218 as covalent circles of deoxyribonucleic acid are similar, and are different from R162/3 . The new plasmids are more likely the result of a substitutive recombination event than a fusion . We propose genetic maps of these recombinant plasmids, showing the unequal participation of the parental plasmids in their formation.

J Bacteriol, 1976 Jan, 125(1), 353 - 65
Actin-like properties from Escherichia coli: concept of cytotonus as the missing link between cell metabolism and the biological ion-exchange resin; Minkoff L et al.; A protein fraction (A-L fraction) with characteristics reminiscent of muscle actin has been isolated from Escherichia coli . The A-L fraction undergoes reversible aggregation under the same conditions in which actin is polymerized and depends primarily on potassium for its polymerization . This fraction, upon electrophoresis on acrylamide gels in the presence of sodium dodecyl sulfate, exhibits a distinct peak at the characteristic molecular weight of 45,000 . Passage of skeletal muscle myosin through the A-L fraction specifically removes this 45,000-molecular weight peak . Examination of the myosin by sodium dodecyl sulfate electrophoresis after the passage reveals a new band at the proper molecular weight . The A-L fraction from wild-type E . coli is compared with the protein from a potassium transport mutant . Important catalytic differences exist between the A-L fractions of the two strains . The A-L fraction from the mutant fails to polymerize in low-K media in the K+ concentration range in which the mutant fails to take up to K+ . In low-K+ media, the parent strain accumulates potassium and the A-L fraction from this organism polymerizes . The cell swelling reaction of both strains has been studied . Parent cells swell during low-K+ uptake, whereas the mutant does not . It is construed from this that the differences in the characterization of the A-L fraction relative to that of the wild type are related to the loss of cell swelling in the mutant and hence to the loss in alkali cation selectivity . The possible role of contractile proteins in biological ion exchange is discussed.

J Bacteriol, 1976 Jan, 125(1), 346 - 52
Direction of deoxyribonucleic acid replication in Escherichia coli under various conditions of cell growth; Rodriguez RL et al.; The direction of chromosome replication in a temperature-sensitive initiation mutant of Escherichia coli (CT28) is shown autoradiographically to be bidirectional . This mode of replication persists even when the rate of replication is reduced by slow growth in succinate minimal medium or in the presence of chloramphenicol . Therefore, although the rate of replication can be affected by certain physiological stimuli, the topology of replication need not be.

J Bacteriol, 1976 Jan, 125(1), 248 - 57
Morphological analysis of nuclear separation and cell division during the life cycle of Escherichia coli; Woldringh CL; Quantitative electron microscope observations were performed on Escherichia coli B/r after balanced growth with doubling times (tau) of 32 and 60 min . The experimental approach allowed the timing of morphological events during the cell cycle by classifying serially sectioned cells according to length . Visible separation of the nucleoplasm was found to coincide with the time of termination of chromosome replication as predicted by the Cooper-Helmstetter model . The duration of the process of constrictive cell division (10 min) appeared to be independent of the growth rate for tau equals 60 min or less but to increase with increase doubling time in more slowly growing cells . Physiological division, i.e., compartmentalization prior to physical separation of the cells, was only observed to occur in the last minute of the cell cycle . The morphological results indicate that cell elongation continues during the division process in cells with tau equals 32 min, but fails to continue in cells with tau equals 60 min.

J Bacteriol, 1976 Jan, 125(1), 233 - 47
cis-Dominant, transfer-deficient mutants of the Escherichia coli K-12 F sex factor; Guyer MS et al.; Rare conjugational progeny formed by crossing each of five Hfr strains with a recA-F- strain have been characterized . Selection was made for a proximal Hfr marker, taking strict precautions to prevent transfer of recA+ to the zygotes . Most of the progeny were found to be F' strains containing deletion mutant plasmids . With two exceptions, these mutant plasmids have lost all of the tra genes, which are required to confer conjugational donor ability upon a host . In addition, all but the exceptional mutant plasmids were found to be very poorly transmissible from transient heterozygotes which also contain a wild-type F' plasmid . The poor transmissibility is a cis-dominant transfer-defective phenotype which may result from deletion of all or part of the origin of transfer replication (ori), or of a gene determining a cis-acting protein . The two exceptional mutant plasmids may carry short deletions of some of the tra genes or polar tra mutations . The remaining progeny were nonmutant F' strains and F- strains . The frequency with which the F- strains were recovered permits us to estimate that the maximum amount of recombination possible in a recA56 zygote is 10(-6) that of a recA+ zygote.

J Bacteriol, 1976 Jan, 125(1), 220 - 4
Excision of pyrimidine dimers in toluene-treated Escherichia coli; Deutsch WA et al.; Toluene-treated cells were used for examining excision of pyrimidine dimers in Escherichia coli strains W3110, DM845 (uvrA-), P3478 (polA-), and KS5064 (polAex1) . Excision occurring in toluene-treated cells is rapid, adenosine 5'-triphosphate dependent, and requires the uvrA gene function . In strains lacking either the polymerizing or 5' leads to 3' exonucleolytic activity of deoxyribonucleic acid polymerase I, excision does occur . However, both in vivo and in vitro, the excision in such strains is initially slower than wild type.

J Bacteriol, 1976 Jan, 125(1), 205 - 10
Inhibition of nucleoside Q formation in transfer ribonucleic acid during methionine starvation of relaxed-control Escherichia coli; Katze JR et al.; The elution profiles of Asp-tRNA from unstarved and starved cultures of a relaxed-control (Rel-) strain of Escherichia coli were compared by reversed-phase chromatography . Methionine starvation results in the appearance of several additional species of Asp-tRNA which are not observed with starvation for leucine or histidine . By the criterion of cyanogen bromide-effected shifts in chromatographic elution position, a large portion of the tRNAAsp synthesized in methionine-starved cells lacks the normal Q nucleoside . By the same criterion, virtually all of the tRNAAsp from unstarved, leucine-starved, and histidine-starved cells contain Q . We conclude that methionine starvation prevents the formation of the norma Q nucleoside in Rel- E . coli.

J Bacteriol, 1976 Jan, 125(1), 191 - 6
Deoxyribonucleic acid polymerase II activity in an Escherichia coli mutator strain; Smith CL et al.; The polB gene encoding deoxyribonucleic acid (DNA) polymerase II has been located close to a mutator gene, mutT1, in Escherichia coli . We find the DNA polymerase II prepared from mutT1, strains to be normal in reaction requirements, heat stability, and ability to remove mismatched bases at termini . Recombinants formed from a mutant defective in DNA polymerase II (polB100) and mutT1 are deficient in polymerase II and have the same mutator phenotype as mutT1 . Our linkage analysis indicates that mutT1 and polB100 are not isoallelic.

J Bacteriol, 1976 Jan, 125(1), 111 - 8
Inactivation of adenosine 5'-triphosphate synthesis and reduced-form nicotinamide adenine dinucleotide dehydrogenase activity in Escherichia coli by near-ultraviolet and violet radiations; Lakchaura BD et al.; Near-ultraviolet (near-UV) light (300 to 380 nm) is a significant component of sunlight and has a variety of effects on biological systems . The present work is an attempt to identify chromophores (molecular absorbers of light) and targets (critical damaged molecules) for inhibition of adenosine triphosphate (ATP) synthesis in Escherichia coli by near UV . The fluence of 334 nm required for 37% survival of net ATP synthesis (F37) in E . coli AB2463 in succinate medium is 140 kJ/m2 . The action spectrum for this inactivation is almost structureless, exhibiting a smooth transition from high efficiency at 313 nm to low efficiency at 405 nm . The action spectrum for inhibition of net ATP synthesis is consistent with the chromophore being either ubiquinone Q-8 or vitamin K2 . The fluence required is consistent with ubiquinone Q-8 also being a target molecule . The activity of reduced nicotinamide adenine dinucleotide dehydrogenase in extracts of E . coli B is also inactivated by near UV and shows an F37 of about 40 kJ/m2 . The action spectrum for this effect is quite structureless; it shows high efficiency at 313 nm and low efficiency at 435 nm . The data do not suggest a target molecule for this action, although it is possible that ubiquinone Q-8 absorbs the near-UV energy and then passes it on to some other target molecule . The data further indicate that inactivation of the oxidative phosphorylation system is not a primary factor in near-UV-induced growth delay in E . coli.

J Bacteriol, 1976 Jan, 125(1), 102 - 10
Genetic control of multiple pathways of post-replicational repair in uvrB strains of Escherichia coli K-12; Youngs DA et al.; The effect of the recA, uvrD, exrA, and recB mutations and of post-irradiation treatment with chloramphenicol on the survival and post-replication repair after ultraviolet irradiation of uvrB strains of Escherichia coli K-12 was examined . Each of these mutations or treatments was found to decrease survival and the extent of repair . The interactions of the inhibitory effects of the uvrD, exaA, and recB mutations and chloramphenicol treatment were determined by examining the survival and repair characteristics of the several multiple mutants . The survival results suggest that the post-replication repair process in uvrB strains may be subdivided into at least five different branches . These include three branches that are blocked by the exrA, recB, or uvrD mutation, a fourth branch that is blocked by any of these mutations and is also sensitive to chloramphenicol treatment, and at least one additional branch that is not sensitive to either of these mutations or to chloramphenicol treatment . The extent of post-replicational repair observed with each of the strains is in general agreement with the pathways postulated on the basis of the survival data, although there are several apparent exceptions to this correlation.

Int Arch Allergy Appl Immunol, 1976, 50(2), 164 - 71
Antibodies against Escherichia coli O antigen . Antibody amounts and avidities measured with ammonium sulfate precipitation technique; Ahlstedt S et al.; The ammonium sulfate precipitation (ASP) technique, modified Farr assay, has been utilized to study antibodies to Escherichia coli O2, O4, O6 and O75 antigens the induction of which could not be ascribed to the effect of a defined antigen . It was noted that the antibody titers against the O6 antigen in children, 0.1-2.5 years of age, were of lower magnitude than the others, significantly for the O2 and O4 antigens . Comparison between boys and girls under and over 1.0 year of age revealed higher titers in sera from girls and in the older children . However, significant differences were obtained only in a few instances . The antibody avidities were in most cases low and no correlation was found between antibody quantity and avidity . In consecutive samples from adults a varying pattern of antibodies to the O6 and O75 antigens was observed.

Nephron, 1976, 16(3), 236 - 9
Actinomyces peritonitis associated with dialysis; De Santo NG et al.; A case of actinomyces peritonitis occurring in a young girl undergoing regular dialytic treatment is reported . The peritoneal localization was the only one detectable and occurred in a patient who at the beginning of the dialytic treatment had received peritoneal dialysis on two occasions . During 4 months of treatment the patient underwent surgical drainage of the peritoneal fluid and medical treatment with various antibiotics . Super-infection with Escherichia coli and Candida, and an acute episode of bronchopneumonia, complicated the course of the treatment which was finally successful

Ann N Y Acad Sci, 1976, 276, 466 - 78
Discussion paper: impairment of B-lymphocyte functions in concanavalin A-treated friend virus infected mice; Kateley JR et al.; Friend leukemia virus (FLV) leukemogenesis was prevented by treatment of the virus with Concanavalin A (Con A) . Mice infected with the lectin-treated virus, however, showed evidence of a dormant infection since infectious virus could be recovered for as long as 100 days . Humoral immune responses to sheep erythrocytes (SRBC), a thymus-dependent antigen, and to E . coli lipopolysaccharide (LPS), a thymus-independent antigen, were depressed (approximately 80-90%) in mice given the Con A-treated FLV . Cell transfer studies indicated that the impaired responsiveness to SRBC was related to a defect in B-lymphocyte function, similar to the impairment in mice infected with untreated FLV . The mitogenic response of splenocytes from Con A-FLV mice to E . coli LPS was also depressed as was the ability of Ig-bearing spleen cells to redistribute these immunoglobulin receptors into polar caps . The impaired immune responsiveness in the Con A-FLV infected mice appeared associated with the persistent virus infection and not to neoplastic transformation generally associated with leukemogenic process.

Cancer Res, 1976 Jan, 36(1), 73 - 6
Stimulatory effects of 5-lodo-2'-deoxyuridine on number and function of splenic B- and T-cells and of macrophages in C3HeB/FeJ mice; Anaclerio A et al.; 5-lodo-2'-deoxyuridine (lUdR) significantly increases the total number of spleen cells on the fourth day after administration of 100 mg/kg in normal C3HeB/FeJ male mice . The number of splenic B-cells {cells sensitive to the cytotoxic activity of a rabbit antiserum to mouse F(ab)2, plus complement} increases on the same day . The number of T-cells (cells sensitive to the cytotoxic activity of a rabbit antiserum to mouse brain-associated theta antigen, plus complement) and of macrophages (adherent-phagocytic cells) does not increase . Spleen cells from lUdR-treated mice show heightened responsiveness in vitro to Escherichia coli lipopolysaccharide or concanavalin A on Day 4 and Days 5 to 6, respectively . The rate of clearance of i.v.-injected colloidal carbon is also increased for 3 days after lUdR . Thus, lUdR is able to functionally activate either T- or B-cells or macrophages, but only to increase the number of splenic B-cells.

Ann N Y Acad Sci, 1976, 276, 431 - 41
Reversal of immunosuppression induced by murine leukemia viruses; Bendinelli M et al.; BALB/c mice infected with Rowson-Parr virus, a lymphatic leukemia virus isolated from the Friend complex, undergo a rapid depression of antibody response . Spleen cells from these mice in culture show a similar deficit in the response to stimulation with sheep red cells and inhibit the reactivity of normal splenocytes . In an attempt to reverse this immunosuppression, near normal responses were obtained in vitro from infected splenocytes by increasing antigen dose, by adding E . coli lipopolysaccharide, or, more effectively, by cocultivating with small numbers of unfractionated or T cell-depleted peritoneal exudate cells (PC), whereas other manipulations proved ineffective . PC did not prevent the inhibition of normal splenocytes by infected spleen cells, but exhibited substantial restorative activity in vivo . In similar experiments, the immunosuppression exerted by the entire Friend complex could be reversed by PC in vitro but not in vivo . These results indicate that a functional deficit of macrophages may be partially responsible for the immunological impairment induced by leukemia viruses and suggest rational approaches to evaluate the relevance of this impairment to oncogenesis.

Ciba Found Symp, 1976, (42), 193 - 208
Intestinal exfoliated cells in infant diarrhoea: changes in cell renewal and disaccharidase activities; Torres-Pinedo R; Lactase deficiency, manifested clinically by lactose malabsorption, is often the only biochemical evidence of a residual disturbance of jejunal mucosal function after Escherichia coli enteropathy in the infant . Villous morphology is usually normal . A sustained depression of the processes of biochemical differentiation of lactase biosynthesis has been postulated to explain similar states of lactase deficiency, but a possible influence of altered epithelial cell turnover on the mucosal lactase levels has not been investigated . In ten infants with a residual lactose malabsorption, after E . coli infection, jejunal cell renewal activity and disaccharidase activities were studied by analysis of the exfoliated cells collected by lumenal perfusion . Significant increases in DNA and protein exfoliation and in the brush border activities of sucrase and lactase were observed during recovery from the malabsorptive disturbance . DNA and protein efflux increased almost linearly during a 20-day period . Lactase was initially four times more deficient than sucrase activity in the exfoliated cells . Both enzyme activities increased at almost identical rates . Therefore, it took longer for lactase activity to return to normal levels . The lactase/sucrase ratios approached normal at the end of the 20-day period . The changes in the exfoliating levels of the two enzymes, when analysed in relation to the increases in cell renewal activity, suggested a relationship between sucrase and lactase levels and cell age.

Somatic Cell Genet, 1976 Jan, 2(1), 63 - 76
Nucleotide analysis of DNA and RNA in cells with thymidine totally replaced by bromodeoxyuridine; Bick MD et al.; The nucleotide composition of nuclear DNA has been determined in a cell line (HAB) that has grown for 275 generations with complete substitution of bromodeoxyuridine (BrdU) for thymidine in nuclear DNA . Within 50 generations there is a approximately 3% decrease in the G content and an equivalent increase in the BrdU content of DNA, relative to the unsubstituted parent cell line . However, these alterations do not continue to accumulate when the cells are grown for up to 275 generations with fully substituted DNA, suggesting that they are not brought about by BrdU-induced base transitions due to mispairing . RNA transcription has been examined both in vivo and in vitro to determine whether or not BrdU substitution in DNA results in large-scale transcriptional errors . The nucleotide composition of 18S and 28S rRNA from cells 0, 60%, and 100% substituted with BrdU does not significantly differ . Further, when DNA from these cells is transcribed in vitro with E . coli RNA polymerase, there is no evidence for altered incorporation of nucleotides into RNA made from the substituted templates.

Biochimie, 1976, 58(11-12), 1355 - 8
{Biological methylations in the crab Carcinus maenas; in vitro inhibition by a fraction purified from androgen gland extracts}; Tekitek A et al.; Extracts from muscles, testis, seminal vesicles and ovaries of the Crab, Carcinus maenas, have been studied in vitro, in presence of {14C}-methyl S-adenosylmethionine, with an E . coli tRNA as methyl acceptor . The highest level of methylases is found in the testis . It has been reported previously that a purified fraction extracted from the androgenic glands of Carcinus maenas inhibits the vitellogenesis in ovaries . We now show that the same fraction inhibits tRNA methylation in an extract of testis as methylase; a 50% inhibition is obtained with about 10 mug of a purified fraction corresponding to 15 glands . With an enzymatic preparation from the ovaries, a 50% inhibition of the tRNA methylase is observed with the purified extract from 4 glands.

Biochimie, 1976, 58(11-12), 1337 - 44
Transfer ribonucleic acid methylase activity in adult and foetal rat liver; Landin RM et al.; Foetal rat liver extracts were found to have higher tRNA methylene activities than corresponding extracts of adult liver . When the specific activities were expressed per mg of liver or per mg of protein, the foetal tRNA methylating enzymes were respectively 2.5 and 6 times higher than those of adult livers . The presence of an inhibitor in adult liver can be excluded, since the same recoveries of total tRNA methylase activity were obtained after partial purification of both adult and foetal liver extracts: yields were close to 100% . The apparent Km's for the substrates in the methylating reactions were the same when tRNA methylases from either adult or foetal liver were used: values were 0.2 muM for Escherichia coli tRNA and 2.1 muM for S-adenosyl-L-methionine . After T1-T2 ribonuclease digestion of an in vitro methylated tRNA, similar methyl nucleotide patterns were observed in foetal and adult enzymatic extracts . It is concluded that the same tRNA methylase pool is present in adult and foetal liver . In addition, it is hypothesized that the different reaction rates exhibited by these enzymes might be due to the tRNA functional requirements rather than to the presence of a tRNA methylase inhibitor.

Genetika, 1976, 12(9), 112 - 7
{New lambdoid phages of Escherichia coli . II . Comparison of several genetic characteristics with lambda phages}; Tsygankov IuD et al.; Functions of some newly isolated lambdoid phages and phage lambda genes were compared by their ability to interact with unrelated phages and the product of the bacterial gene gro P . 19 of 23 lambdoid phages studied interfere with prophage P2, that points out the presence of functionally active genes, essential for spi+ phenotype in their genomes . The development of 4 lambdoid phages with spi- phenotype is independent on the prophage P2 presence . Most of lambdoid phages show the reduced growth ability on the C600 groP- bacterial lawn . This indicates that they have a function similar to the gene P of phage lambda . The development of phage phi M417 in bacterial mutants groP- is not disturbed, which indicates that the gene P of phage phi M417 is different from that of the phage lambda . Newly isolated phages, that are homoimmune to phage lambda, restrict the development of T4 rII phage . The rest lambdoid phages have no rex function . The growth efficiency of lampodid phages on E . coli C cells, carrying Eco R1 plasmid, varies from 10(-6) to 10(-8) that presumbaly indicates on different amounts of restionci strites in DNA of these phages.

Genetika, 1976, 12(9), 104 - 11
{New lambdoid Escherichia coli phages . I . Isolation, group immunity and recombination with lambda phage}; Krylov VN et al.; 550 bacterial strains were isolated from sewage . 69 of them were lysogenic by phages active on Escherichia coli . The phages were divided into two groups on the basis of UV-inducibility, the ability to form plaques on Rep-E . coli mutants and particle morphology: lambdoid (23 phages) and related to P2 (46 phages) . Hybrid phages isolated from the crosses of lambdoid phages with phage lambda harboured the region imm lambda and the gene of adsorption specificity from other parent . Ten groups of heteroimmune phages were found in the collection of new temperate phages are homoimmune with known phages: lambda, phi 80, phi 81, 434 . Another 7 phages involved in 6 groups of immunity which were heteroimmune to known phages . Diversity of lambdoid phage genes determining the structure of repressor is discussed.

Acta Biol Med Ger, 1976, 35(8-9), 1141 - 9
Effects of prostaglandins in canine endotoxin shock; Shatney CH et al.; Endotoxin shock was produced in healthy, adult mongrel dogs by the intravenous injection of 1.5 mg/kg of E . coli endotoxin . The 24 hour survival of untreated animals was 34% and was not enhanced by volume replacement with low molecular weight dextran . Treatment with dextran and prostaglandin A1 or E1, although effecting significant hemodynamic improvements, did not increase survival.

Genetika, 1976, 12(8), 131 - 8
{Substrate of a UV-induced repair system providing for W-reactivation of lambda phage}; Mosevitskaia TV et al.; Escherichia coli uvrA, polA and uvrD cells carrying non-UV-inducible prophage lambdac1857ind- were infected with 3H-thymidine labelled homoimmune phage lambdac1857, and the effect of UV-irradiation of super-infecting phage and lysogenic bacterial cells on the content of intracellular covalently-closed lambda DNA circles (cccDNA) and pyrimidine dimer content in lambda DNA are studied . UV-irradiation of host cells results in two-fold increase of relative content of cccDNA of UV-irradiated phage lambda in uvrD mutant, while there is no such an effect in uvrA and polA mutants . In UV-irradiated or intact uvrA lysogens cccDNA molecules, forming after the infection with UV-irradiated phage lambda, contain pyrimidine dimers, but in uvrD mutant cccDNA in free of dimers . The data indicate that the repair system induced by UV-irradiation of uvrA and polA cells acts exclusively on the DNA defects appearing after (or in the course) of phage genomes replication . UV-inducible repair system in uvrD mutant can operate also on some intermediates of abortive excision repair, possibly on long single straided excision gaps.

Genetika, 1976, 12(6), 95 - 102
{Suppression of DNA-ligase deficiency and selective breeding of mutants and recombinants of T4 phage with phenotype rII}; Chirkov GP et al.; A number of methods which greatly simplify the introduction of frame shift mutations in the limited segment of the phage T4 rII genes were developed for studying genetical recombination between closely linked markers . These methods enable to construct multiple rII mutants with relatively small expenditure of labour . Suppression of gene 30 deficiency by rII mutations has been studied for a variety of conditions . The results obtained indicate that rIIB polypeptide is involved in two different activities: rIIB region which is dispensable for growth on lambda-lysogenic Escherichia coli strains behaves as indispensable in phenomenon of suppression of ligase deficiency.

Dev Biol Stand, 1976, 33, 29 - 32
Non-parenteral vaccines for veterinary use in the United Kingdom; Frerichs GN; The first vaccine specifically formulated for non-parenteral administration was licensed for use in the United Kingdom over 15 years ago . Since that time there has been a dramatic increase in the use of this type of product, particularly within the last five years, and at present no fewer than 46 of the 220 currently licensed vaccines are recommended for administration by the non-parenteral route . The majority (42) of these products are for use in poultry with the remainder being for cattle, pigs and mink (1 vaccine each) . All except two of the products are viral vaccines, the exceptions being a cattle helminth vaccine and the pig vaccine which is used for the control of intestinal E . coli infections in the young animal . Administration is principally by mouth, the vaccines being given either directly by the oral route to individual animals or incorporated in drinking water or feedstuffs for mass medication purposes but spray and eye-drop administration methods are also used.

Prep Biochem, 1976, 6(5), 339 - 46
Separation of Met-tRNAf and Met-tRNAm by chromatography on Sepharose 4B columns; Nygard O et al.; Unfractionated rabbit liver tRNA, charged with {3H}methionine by use of rat liver enzymes, was separated into two {3H5methionine-containing fractions by column chromatography on Sepharose 4B . The two fractions were identified as Met-tRNAMetm and Met-tRNAMetf by (a) their different ability for form a GTP-dependent ternary complex with IF-MP, and (b) the absence of the first fraction after selective charging of the tRNA with E . coli amino acyl tRNA synthetase . The methionine residue was without noticeable influence on the separation.

Int J Pept Protein Res, 1976, 8(4), 349 - 56
Structure-activity studies on mammalian tissue lytic enzymes: chemical characterization and substrate specificity of rat kidney nuclear lysozyme; Raghunathan R et al.; Studies on the structure and substrate specificity of purified rat kidney nuclear (RKN) lysozyme are reported . The carboxyl and amino terminal residues of RKN-lysozyme were found to be leucine and alanine respectively . The amino acid composition indicated similarities and differences as compared with that of hen egg white (HEW) lysozyme . There were alterations in the nine amino acid residues, Lys, His, Arg, Asp, Glu, Pro, 1/2 Cys, Tyr and Trp . The other nine residues were present in identical proportions to those of HEW-lysozyme . The decrease in the arginine and aspartic acid residues was found to be compensated by the increase in the number of lysine, histidine and glutamic acid residues . The overall ratio of the acidic to basic amino acids has thus been conserved in the mammalian enzyme . In addition, RKN-lysozyme contained decreased numbers of Trp, Tyr and 1/2 Cys, and increased numbers of proline residues as found in HEW-lysozyme . RKN-lysozyme did not cross react with heterologous antibodies produced against HEW-lysozyme, and vice versa . RKN-lysozyme showed distinct specificity towards the lysis of M . luteus . Against this substrate, it was three times more efficient than HEW-lysozyme . It also cleaved E . coli B, but its efficiency was half as much as with M . luteus . However, it cleaved P . septica and B . subtilis at a rate similar to HEW-lysozyme under identical conditions.

Acta Haematol, 1976, 56(2), 73 - 7
Response of blood and bone marrow neutrophils to the nitroblue-tetrazolium test in children; Cassimos C et al.; The ability of blood and bone marrow neutrophils to reduce nitroblue-tetrazolium both before and after stimulation with Escherichia coli endotoxin was investigated . The polymorphonuclear cells of the bone marrow are less able to reduce the dye than blood cells . This difference is maintained after stimulation by endotoxin . Early forms of neutrophils (myelocytes and metamyelocytes) have some reducing ability but this is more marked after stimulation with endotoxin.

Chemotherapy, 1976, 22(5), 277 - 85
Relationships between the concentrations of doxycycline in serum and in thoracic duct lymph after oral and intravenous administration in man; Anderson KE et al.; The concentrations of doxycycline in serum and in thoracic duct lymph at various times after oral and intravenous administration of 200 mg of the drug were determined in 10 patients subjected to thoracic duct cannulation for diagnostic purposes . After oral administration, a mean peak serum concentration of 2.4 mug/ml (n=7) was obtained within 3 h; then the levels successively declined . The concentrations in thoracic lymph were lower, a mean peak concentration of 1.6 mug/ml being found 3 and 6 h after the intake . After intravenous administration (n=3), the concentrations of doxycycline in thoracic duct lymph were lower than but closely followed those in serum . The difference in concentrations between serum and lymph 1-6 h after the start of the infusion never exceeded 30% . The results suggest that doxycycline is rapidly distributed to the extracellular tissue fluids.

Acta Physiol Lat Am, 1976, 26(5), 330 - 6
Purification of polyribosomes, 70S, monomers or ribosomal subunits by gel filtration; Garcia-Patrone M et al.; Chromatography through Bio-Gel columns is a simple and rapid method for the purification of different ribosomal particles . This mild procedure, easily adapted to many purposes with good yields, can substitute the conventional sucrose gradient centrifugations, especially when the integrity of labile particles or complexes must be preserved.

Acta Physiol Lat Am, 1976, 26(5), 289 - 96
{Studies on the initiation of glycogen metabolism in Escherichia coli (author's transl)}; Barengo R et al.; Glycogen biosynthesis was studied in Escherichia coli . An enzyme complex composed of UDP-glucose; protein glucosyltransferase, ADP-glucose: protein glucosyltransferase and ADP-glucose: alpha-1,4 glucan alpha-4-glucosyltransferase was found . Further results revealed that while glycogen concentration remained unchanged, the specific activity of the glucosyltransferase complex increased during the growth phase of the culture . The detergents Lubrol and Brij provoked a decrease of 80% and 20% in the glucose transfer to protein from ADP-glucose and UDP-glucose, respectively . These detergents did not inhibit the glucose incorporation into glycogen by ADP-glucose: alpha-1,4-glucosyltransferase . We postulated that the biosynthesis of glycogen in Escherichia coli could be initiated by two different enzymes which catalyze the transfer of glucose from UDP-glucose or ADP-glucose to an acceptor protien . In a second step, the glucan protein formed is used as primer by the ADP-glucose: alpha-1,4 glucan alpha-1-glucosyltransferase for glycogen formation.

Acta Biol, 1976, 27(2-3), 119 - 24
Effect of endotoxin on the peritoneal mast cells in mice; Jokay I et al.; Endotoxin administered intraperitoneally has been found to decrease the absolute and relative number of the peritoneal mast cells in mice . The number of peritoneal mast cells showed a dose-dependent biphasic response to endotoxin . Maximal and more consistent decrease in the peritoneal mast cell count was observed at about 24 h and lasted for at least 4 days . Mast cell damage also occurred . The possible mechanism of this phenomenon is discussed.

G Batteriol Virol Immunol, 1976 Jan-Jun, 69(1-6), 85 - 90
{Oral immunization of human adult volunteers using a trivalent coli-vaccine}; Barbaro S et al.; Oral vaccination of 19 human adult volunteers with a killed trivalent E . coli vaccine induced an antibody response detectable either in sera and feces . Production of specific IgA immunoglobulins in the intestine was also observed . Antibody titres reached the highest levels 5-10 days after vaccination and were still detectable in the majority of volunteers about 2 months later.

Arch Exp Veterinarmed, 1976, 30(6), 951 - 7
{Effect of acetylsalicylic acid on experimentally induced endotoxin reactions in swine}; Schimmel D et al.; The time and severity of clinical responses to endotoxin depend on dosage, Administration of acetylsalicyclic acid and Indometacin prior to endotoxin application may delay or moderate the clinical phenomena that are likely to result from certain endotoxin amounts.

Arch Exp Veterinarmed, 1976, 30(6), 853 - 9
{Experimental studies on the pathogenesis of coli enterotoxemia in swine . 3 . Effect of coli enterotoxin in weaned piglets following intragastric administration}; Johannsen U; The following results were obtained from experiments with 23 clinically intact weaned piglets, aged between five and six weeks (18 animals) or eight weeks (five animals), which had received three intragastric applications of crude enterotoxin (culture filtrate supernatant of Escherichia coli O149:K91(B)K88(L): . 1 . Twelve animals (52 per cent) responded to enterotoxin application by temporary outbreaks of diarrhoea (1-8.5 hours) following differentiated latencies (2.5-10 hours) . No diarrhoea was recorded from eleven piglets (48%) which had received the same doses of enterotoxin . 2 . No signs of a systemic disease were clinically recordable after enterotoxin administration from 22 (96%) animals, no matter whether diarrhoea had developed or not . Respiration, temperature, heart rate, and haematological values were unchanged . Feed and water intake were normal . No exsicosis was observed . All animals exhibited lively behaviours and activity . The conclusion drawn regarding the pathogenesis of the gastrointestinal form of coli-enterotoxaemia, with reference to the authors' own earlier findings, is that in this disease parenteral endotoxin effects (following endotoxin resorption) seem to coincide with enteral enterotoxin effects.

Arch Virol, 1976, 52(4), 315 - 21
The use of agarose gels for the assay of the deoxyribonuclease activity associated with the soluble penton of adenoviruses; Medveczky P et al.; Evidence is presented that the excess pool of penton complexes purified from adenovirus type 1-infected HEp-2 cells also carry an endonucleolytic activity . The effect was measured with both E . coli and adenovirus type 1 double-stranded DNA substrates . The use of agarose gels for assaying the endonuclease activity allowed the approximative calculation of the number of penton molecules which might produce one DNA double-strand break under the experimental conditions selected.

Arch Exp Veterinarmed, 1976, 30(5), 709 - 25
{Pathology and pathogenesis of coli dysentery and coli diarrhea in suckling piglets . 2 . Studies on the experimental induction of disease through the intragastric administration of coli-enterotoxin}; Johannsen U; Fractionated intragastric application of a crude enterotoxin of Escherichia coli O 149:K91 (B) K88 (L) was part of experimental intoxication of 88 nursed piglets, aged between one and three days . The experiment was based on culture filtrate supernatant which had produced positive enterotoxic effect in an intestinal ligature test of swine and rabbit . The results were compared with 50 controls, piglets of the same age with intragastric administration of physiological salt solution . The experiment gave pronounced aquaeous diarrhoea (100 per cent) accoumpanied by exsiccosis, weight loss, rough hair, greyish discoloration of the skin, and other manifestations . The mortality was nine per cent . The clinical and pathomorphological picture of the enterotoxin syndrome was in close agreement with spontaneous coli-bacillosis of nursed piglets . Enterotoxin-caused diarrhoea occurred, with the gastro-intestinal mucous membrane remaining morphologically intact . This intoxication method has proved to be a safe model for experimental induction of coli-bacillosis, and it is likely to be suitable for vaccine testing . It can be used, as well, as a simple qualitative enterotoxin test . Additional issues relating to the pathology and pathogenesis of the coli-enterotoxin syndrome of piglets are discussed.

Arch Exp Veterinarmed, 1976, 30(5), 687 - 708
{Pathology and pathogenesis of coli dysentery and coli diarrhea in suckling piglets . 1 . Studies on the pathomorphology of the gastrointestinal tract in coli dysentery as well as coli diarrhea in the suckling piglet}; Johannsen U; The following findings were obtained from histomorphological examination of 45 piglets with coli-bacillosis (with serotypical Escherichia coli detected) and ten piglets with coli-diarrhoea (with non-serotypical E . coli detected): Diarrhoea accompanying either disease was not attributable to catarrhal or haemorrhagic gastro-enteritis . The mucous membrane of the gastro-insestinal tract remained histomorphologically intact in either disease . No change was recorded particularly from villous or surface epithelia and glandular epithelium, and the villous structure was not basically altered . Different degrees of hyper aemia of the gastro-intestinal mucous membrane and moderate oedematisation of the villous stroma were irregular findings . Adhesion of enteropathogenic E . coli to mucous membrane surface was observed but rarely and did not exhibit any visible relationship with the incidence in E . coli of L-antigen K88 . In coli-bacillosis and coli-diarrhoea both the diarrhoea and morphological situation of the gastro-bacillosis tract were in conformity with the cholera-type "intestinal noninflammatory secretory diarrhoea" as caused by enterotoxins . Other issues relating to pathology and diagnosis are also discussed.

Zentralbl Bakteriol Parasitenkd Infektionskr Hyg, 1976, 131(3), 501 - 5
Biological studies on a strain of Escherichia coli B resistant to chlorpromazine; Mostafa SA; A strain of Escherichia coli B resistant to chlorpromazine was developed from the sensitive strain . Cells of the resistant strain were different from those of the sensitive strain . Thus, the premeability of the resistant cells (measured by the uptake of 14C-glutamic acid) was not interfered with by Cpz . Moreover, the resistant cells were able to cause detoxification or partial detoxification of the durg.

Genetika, 1976, 12(9), 154 - 63
{Detailed model of semi-conservative DNA replication . Possible role of DNA-polymerase errors in fragmented copying of both matrix strands}; Mosevitskii MI; A model of semiconservative DNA synthesis is considered . The model is based on a suggestion that the synthesis proceeds in the course of one-directional stretching of both matrix strands through the replicase complex (replisome), or of one-directional movement of the replisome along the chromosome . Each nucleotide link of the matrix strand find itself successively in the section of RNA primer synthesis, in the section of DNA polymerase and in the control section of a proofreading 3' leads to 5' exonuclease . Deoxynucleoside incorrectly joined by DNA polymerase of the replisome to the 3'-OH end of growing chain are, as a rule, removed when transferred in the control section . Since the reverse movement is prohibited, the DNA polymerase loses the 3'-OH end of new DNA chain and proves to be incapable to continue the synthesis . It can be renewed only after a new RNA primer formation . For continuation of the DNA synthesis after an incorrect deoxynucleotide addition, replicase must take two more mistakes in succession: to retain the incorrect nucleotide and to join the next one to this unproperly arranged primer . Only in that case the non-complementary nucleotide in a new DNA chain can escape the action of proofreading exonucleases . Hence, according to the model under discussion, the frequency of mutations should be many times lower than that of incorrect nucleotide joinings . The latter results, as a rule, in DNA chain synthesis cessation and in fragments formation . Taking into consideration the frequency of spontaneous mutations in bacteria (about 10(-9) per base-pair), the frequency of non-complementary joinings during semiconservative synthesis can be suggested of the order 10(-3) in accordance with the average Okazaki fragments size of 1000 nucleotides . Another possible reason for periodical interruptions of semiconservative DNA synthesis and for fragments formation is a distortion of replisome structure, accompanying the release of the matrix strand being copied in the direction of already replicated chromosome region . Both mechanisms can participate concurrently in DNA fragments formation . If replisomes are attached to a cell membrane, the sites of chromosome that are also fastened in the membrane, in particular, the site of "origin", are to be replicated using some mobile replicase complex.

Genetika, 1976, 12(11), 162 - 4
{Transmissible hybrid plasmid RP4-ColE1}; Stepanov AI et al.; Hybrid plasmid RP4-ColE1 was obtained by joining DNA plasmids RP4 and ColE1, each of which possessed only one site of restriction for EcoR1 . These plasmid molecules were restricted by endonuclease EcoR1 and then treated by ligase . The hybrid plasmid retained the property of transmissibility typical for drug factor resistance RP4 . Non-transmissible mutant of the hybrid plasmid selected by the character of the resistance of Escherichia coli C600 (RP4-ColE1) to the phage PRR1 is used for subsequent investigations.

Genetika, 1976, 12(11), 101 - 14
{Reversion of RNA-polymerase mutations affecting F'-factor stability}; Mindlin SZ et al.; Ts+ reversions of amber mutations tsR on the beta-subunit of Escherichia coli RNA polymerase (79 min on the genetic map) were investigated . TsR mutants are viable due to the partial suppression of amber mutations by su2 suppressor . Three types of reversions were isolated in the course of the selection for Ts+ character, namely, intragenic reversions and two types of extragenic reversions, located at different regions of the bacterial chromosome . The mutation N5, located between 0 and 15 min . on the map, increases practically to normal the amount of RNA polymerase beta-polypeptide, which is diminished as a result of ts22 amber mutation action, and increases the plating efficiency of several T4 phage amber mutants . The mutations designated as D are located on the chromosome near the spcA locus (64 min . on the E . coli map) . These mutations are characterized by pleiotropic effect . They have properties of a weak suppressor increasing the efficiency of su2 action on amber mutations of E . coli and phage T4 . At the same time D mutations are capable to decrease sharply the efficiency of the crosses with F' strains . Both these characters determined by D mutations do not segregate in transduction . It is suggested that the decrease of sexduction by D mutations depends on their influence on replication of episomes in the recipient cells.

Genetika, 1976, 12(8), 110 - 5
{Competency of Escherichia coli cells . IV . Effect of freezing--thawing on the formation of competency in Escherichia coli cells in the presence of Ca++ ions}; Rudchenko ON et al.; The paper is initiated in the aim to use the effect of freezing-thawing in the system of intact Escherichia coli cells treated with Ca++ ions to increase the transfection efficiency . It is demonstrated that freezing-thawing of Ca++ treated cells increases the transfection indices of lambda phage DNA for E . coli Hfr clone with low transfection indices in 20-30 times, and for the strain of E . coli X7026 of high competence-in 5 times . Freezing-thawing efficiently increased the transfection only in cells with a decreasing competence . E . coli Hfr H cells acquired the capacity of more efficient lambda phage DNA perception independently on the growth phase, while in E . coli X7026 cells the maximal transfection increase under the effect of complementary interactions was observed at the beginning of the logariphmic and stationary growth stages, but not during the competence period . Short-term changes emerging in cells during freezing-thawing can probably promote the better penetration of Ca++ ions to active sites on the cell surface, which produces favourable conditions for lambda phage DNA formation.

Genetika, 1976, 12(8), 100 - 3
{Transforming activity of Escherichia coli DNA fragments obtained following endonucleolytic splitting by EcoRI restrictase}; Kalinina NA et al.; Escherichia coli DNA with molecular weight of 20 - 10(6) daltons was digested by restriction endonuclease EcoR1, and the transforming activity of resctricts was studied . The transforming activity of restricts for two markers (Leu and Arg) was 2-5 fold increased, for two other markers (Thr and His) was not changed, and for one marker (Pro) was completely absent . The molecular weight of E . coli DNA restricts was 7,5-10(6) daltons . An increase and a decrease of the transforming activity for different markers appeared to be the result of two effects: 1) more efficient uptake of low molecular weight DNA into the cell and 2) the inactivation of markers as a result of location close to EcoR1 induced break.

Genetika, 1976, 12(7), 100 - 8
{Phenotypic manifestation of mutations involving resistance to 2,6-diaminopurine (apt) in the genome of purine auxotrophs of Escherichia coli K-12}; Kocharian ShM et al.; Strains of Escherichia coli K-12 containing various combinations of pur (de novo synthesis of purines), pup (purine nucleoside phosphorylase), add (adenosine deaminase) and apt (adenine phosphoribosyl transferase) mutations have been constructed . The apt mutation blocks the ability of strains of pur add and pur add pup genotype to utilize both adenine and adenosine as sole purine sources . Exogenously supplied histidine (that blocks conversion of AMP to guanine nucleotides) does not reduce the growth rate of the strain of pur apt genotype on adenosine as the sole purine source . Adenine released into the cultural medium of bacteria containing simultaneously apt and pup mutations . This data suggest that cultures of E . coli are unable to phosphorylate adenosine to AMP and that they are capable to degrade adenosine to free adenine without participation of purine nucleoside phosphorylase (gene pup).

Arch Exp Veterinarmed, 1976, 30(4), 553 - 66
{General adaptation syndrome (Selye) in cattle . 6 . Influence of stress conditions on antibody levels after active and passive immunization as well as on the topographic distribution of various groups of pathogens in the gastrointestinal canal}; Hartmann H et al.; The action of experimental and natural stressors on the humoral immune response of calf was studied . Particular attention was given to the H-antigen of S.dublin and equine erythrocytes,the degradation rate of passively acquired humoral antibody, as well as the quantity and topographic distribution of certain groups of germs in the gastrointestinal tract . The following results were obtained:1 . Antibody formation was impededby repeated or lasting stressor effect (ACTH injections) . 2 . The immunological reactions of the calves involved to antigen injection immediately after transport into the rearing unit were stronger than those to antigen application three days from transfer . Immunisation of animals transferred to rearing or fattening units, therefore, should be applied immediately after arrival in the new accomodation, but no interval of three or four days should be allowed . 3 . Antibody formation was no longer impaired in calves immunised two weeks from transfer, as compared to those immunised immediately after arrival in the rearing unit . This seemed to suggest that by that time adaptation of the animals to their new environment had been almost complete . 4 . Lasting stress (slow drip infusion of ACTH, cortisol, colibacteria or coli-endotoxin) led to no detectable by paper electrophoresis . 5 . Calves that had been given three weekly dosesof 1 IU ACTH per kilogram of live weight through four weeks,did not differ,withthe authors'method,from the controls regarding the decomposition rate of passively acquired humoral antibody . 6 . ACTH slow drip infusions of calves over several days caused higher concentrations of colibacteria throughout the intestinal tract, including those proximal sections of the small intestine in which little or no colibacteria should occur under physiological conditions in calves of that age.

Folia Microbiol (Praha), 1976, 21(6), 431 - 7
Simultaneous and gradual induction of beta-galactosidase and tryptophanase synthesis in an Escherichia coli batch culture; Pavlasova E et al.; beta-Galactosidase and tryptophanase can be induced in Escherichia coli simultaneously or gradually during a batch cultivation . In the strain Escherichia coli K 12 and ML 30, in which the synthesis of the two enzymes was induced simultaneously, only the synthesis of tryptophanase partially decreased, whereas the synthesis of beta-galactosidase was not influenced . In the strains B 28 and ATCC 9637 the synthesis of both enzymes was partially decreased . On a gradual induction of these enzymes in the strain Escherichia coli K 12 only the synthesis of tryptophanase decreased . Thus, the results obtained here resemble those observed during the simultaneous induction . In addition, it was found that it is not important which of the two enzymes is induced as the first one.

Genetika, 1976, 12(6), 129 - 34
{Radiosensitive mutants of Escherichia coli with disrupted cell membrane permeability}; Nesterova GF et al.; Membrane proteins and cell permeability of Escherichia coli B/r and different substrains of B/r containing mutations of loci uvrB, exrA, lon and suppressors of that mutations were studied . Membrane proteins were found to be modified only in E . coli B/r exrA . The content of 40 000--70 000 D polypeptides was increased and the content of 80 000--100 000 D polypeptides was decreased . Alteration of membrane proteins in E . coli B/r exrA was associated with the impaired permeability of cell membrane.

Ciba Found Symp, 1976, (42), 45 - 72
Neonatal Escherichia coli infections in domestic mammals: transmissibility of pathogenic characteristics; Smith HW; Apart from the fact that different serotypes are involved, natural and experimental Escherichia coli infection in domestic mammals closely resembles natural E . coli infection in human beings . Some of the important characteristics of E . coli strains that cause disease in domestic mammals are determined by transmissible plasmids . These include enterotoxin, haemolysin and K88 antigen in piglet enteropathogenic strains and enterotoxin and K99 antigen production in calf and lamb enteropathogenic strains; most strains that cause generalized infections in young domestic mammals, i.e . invasive strains, also produce plasmid-determined colicine V . These are all good reasons for employing young domestic mammals as the animal model for studying certain aspects of E . coli infection in human beings . Exploiting the fact that plasmids can be introduced into bacterial cells by conjugation and can be removed from them by "curing", bacterial strains were created that differed from each other, as far as could be determined, only by the presence or absence of one or more of these plasmid-determined properties . These strains, or cell-free preparations of them, were then given by mouth to piglets, calves, lambs and baby rabbits . The results showed that the K88 antigen, probably on account of its adhesive properties, permitted pig enteropathogenic strains of E . coli to proliferate in the small intestine of piglets; the K99 antigen performed a similar function in calf and lamb enteropathogenic strains . The enterotoxin produced by the proliferating organisms was then chiefly responsible for the subsequent movement of fluid from the body into the small intestine and the consequent diarrhoea . Possession of the Col V plasmid contributed significantly to the virulence of invasive strains of E . coli by enabling them to resist more successfully the defence mechanisms of the host.

Ciba Found Symp, 1976, (42), 339 - 66
Taking science where the diarrhoea is; Rohde JE et al.; With attack rates exceeding two episodes per year in the young diarrhoea with attendant dehydration is by far the major single killer in the developing world . An invariable accompaniment of the more insidious and chronic protein-energy malnutrition (PEM), diarrhoea is itself an acute form of malnutrition: fluid-electrolyte malnutrition (FEM) . Scientific attention to FEM has focused heavily on mechanisms of pathogenesis and disordered physiology, often to the neglect of preventive and effective control measures . A notable exception was the huge step from the short-circuit chamber to the cholera ward which carried the science of coupled transport to the field . Glucose-electrolyte solutions provide effective prevention and treatment of dehydration and, where combined with early proper feeding, an interruption of the FEM-PEM cycle . Wider use of this simple technology awaits greater understanding and interact-on with the social systems that determine the ecology of diarrhoeal disease.

Arch Exp Veterinarmed, 1976, 30(3), 379 - 85
{Contributions to the study of properdin . 4 . Report: in vitro model study on the effect of cattle properdin on Escherichia coli}; Zimmermann G et al.; Light and electron microscopy were used in model experiments to study a high-titre "properdine-system" culture and its action in terms of altering E . coli bacteria . The reaction was altogether strongly predominated by the three following phases of lysis . 1 . Onset of massive agglutination after few minutes; 2 . Decomposition of bacterial structure by lysis after ten to twelve hours; 3 . Terminal phase of lysis after two to three days (amorphous detritus).

Arch Exp Veterinarmed, 1976, 30(2), 293 - 8
{The effect of Mecadox on the immune response and on various chicken lymphatic organs}; Giurgea R et al.; Through 35 days Mecadox was admixed to feed rations for chicken, 40 days of age, and inhibited immunogenesis which, generally, is reflected in lowering of antibody titre and gamma globulin level as well as in quantitative variation of the differential leucocyte count . Change of immune reactivity in chicken treated with Mecadox and deviation from the normal are attributable to changes in the organs which are responsible for immunological processes (thymus and bursa), such as reduction of ascorbic acid levels in the adrenal gland.

Z Allg Mikrobiol, 1976, 16(7), 543 - 50
Assimilatory nitrate reductase in a chlorate-resistant mutant of Escherichia coli; Motohara K et al.; Nitrate reductase was investigated in extracts from cells of a chlorate-resistant mutant strain of E . coli which grew anaerobically on nitrate as the sole source of nitrogen . The nitrate reductase was of particulate nature and reduced chlorate like the nitrate reductase from the wild strain, but in contrast was inhibited only weakly by azide or cyanide . Nitrate reductase activity was found in extracts from the mutant cells grown on nitrate as the sole source of nitrogen, but not in extracts from cells grown in complex nutrient medium . Addition of ammonia also caused a decrease in activity . Accordingly, the nitrate reductase in the chlorate-resistant mutant is of the assimilatory type.

Med Pediatr Oncol, 1976, 2(3), 243 - 52
Template properties of human DNA-dependent RNA polymerase II; Garcia HD et al.; DNA-dependent RNA polymerase II has been purified from lymphocytes of patients with chronic lymphocytic leukemia (CLL) . Form II polymerase and Escherichia coli RNA polymerase have been used to study the transcription of human DNA and chromatin . The hybridization kinetics of the transcripts of DNA and chromatin by the human polymerase are quite different; chromatin transcripts hybridized to DNA at a much slower rate than DNA transcripts, whereas the transcripts of DNA and chromatin by bacterial polymerase have similar hybridization kinetics.

J Immunol Methods, 1976, 13(2), 145 - 52
Density gradient electrophoresis of mouse spleen lymphocytes: separation of T and B cell fractions; Platsoucas CD et al.; Preparative electrophoresis in an isotonic Ficoll--sucrose density gradient has been employed for the separation of mouse (C57Bl/6J) spleen lymphocyte subpopulations . The separated cells were pooled into six fractions according to their relative position (Rp) within the total cell distribution . In general, the high mobility cells were identified as T lymphocytes . These cells exhibited immunofluorescence upon reaction with fluorescein isothiocyanate-conjugated mouse anti-theta globulin and responded in vitro to phytohemagglutinin stimulation . The low mobility cells were activated in vitro by E . coli lipopolysaccharide and showed immunofluorescence upon reaction with fluorescein isothiocyanate-conjugated anti-mouse Ig which is typical of mouse B lymphocytes . Both T and B cells were completely isolated from each other in certain fractions of very high and very low mobility, respectively . Overlapping of the two distributions was observed in the intermediate mobility fractions . The method which utilizes an inexpensive commercially available apparatus should be useful for the preparation of other lymphocyte subpopulations differing in surface charge.

Infection, 1976, 4(3), 139 - 45
Escherichia coli isolated from babies delivered by caesarean section and their environment; Lennox-King SM et al.; The sources from which eight Caesarean section babies acquired E . coli are described and the probable routes by which the organisms reached the babies are outlined . Suggestions are made concerning the control of the spread of E . coli in premature nurseries and during outbreaks of E . coli gastroenteritis.

Acta Biochim Pol, 1976, 23(2-3), 243 - 59
Activity of methoxyamine-modified f2 RNA in initiation and elongation steps of protein synthesis; Filipowicz W et al.; 1 . Messenger activity of phage f2 RNA modified with methoxyamine under non-denaturing conditions was studied in E . coli-free system . The incorporation of amino acids into phage polypeptides was decreased, and the synthesis of phage-specific proteins was diminished . The RNA replicase synthesis was more affected than synthesis of coat protein . The impaired messenger activity of the methoxyamine-modified f2 RNA was due to the blocking of elongation process by modified cytosines present in RNA chain . 2 . Specificity of f2 RNA to stimulate ribosomal binding predominantly at the coat protein initiation site was not affected by methoxyamine-treatment, as demonstrated by unchanged binding of f{3H}Met-tRNA and {14C}alanyl-tRNA to ribosomes . 3 . Unfolding of f2 RNA molecule on treatment with methoxyamine in the presence of guanidine-HCl resulted in a significant increase of RNA capacity to direct fMet-tRNA binding to ribosomes . Sucrose-density gradient profiles revealed the formation of polysome-like initiation complexes indicating that ribosomes were able to bind at many hitherto inaccessible initiation codons in RNA molecules . fMet-tRNA bound to ribosomes in the presence of unfolded RNA was found to be fully reactive with puromycin.

Scand J Infect Dis, 1976, 8(3), 195 - 8
A NEW Escherichia coli O-group, O159, associated with outbreaks of enteritis in infants; Gross RJ et al.; An outbreak of enteritis occurred amongst babies in a nursery unit . 25 babies were affected and 5 required intravenous therapy; there were not fatalities . From 24 of the 25 babies affected, an Escherichia coli with a previously undescribed O-antigen was isolated . An outbreak of diarrhoea had taken place in the same hospital a year before and re-examiniation of cultures of E . coli isolated at that time showed that 5 of the 15 babies affected had been excreting E . coli with the same O-antigen . Isolates from 10 of the babies were tested for enterotoxin production in the infant mouse model and 4 gave a positive response . The new O-antigen has been accepted into the international serotyping scheme and has been designated E . coli O159.

Int Arch Allergy Appl Immunol, 1976, 51(5), 560 - 73
Dissociation of correlates of cellular immunity in man: functional heterogeneity within the antigen-reactive cell population?
Holt PG, Fimmel PJ, Bartholomaeus WN, Roberts LM, Tandon MK, Keast D.
Cellular immune responsiveness (CMI) to ubiquitous bacterial antigens was assessed in serial peripheral blood samples collected from normal subjects, employing three in vitro correlates of CMI in parallel . Delayed cutaneous hypersensitivity (DCH) was also assessed on a number of occasions in these subjects . These experiments showed that the reactivity of peripheral blood leukocytes from normal individuals as measured in each of the in vitro tests fluctuated from day to day, and that the reactivity of cells functioning in each of the tests fluctuated independently of one another . In contrast, DCH reactivity in these individuals was not subject to such fluctuations . The results are discussed in terms of the periodic appearance of functionally distinct subpopulations of T lymphocytes in the peripheral circulation.

Biomembranes, 1976, 8, 47 - 88
Intracellular localization and immunogenic capacities of phenotypic products of mouse histocompatibility genes; Manson LA; The transplantation antigens are the phenotypic products of genes which control histocompatibility in vertebrate species . The products of major histocompatibility locus of the mouse, H-2, have been studied as a model . The H-2 transplantation antigens are expressed on cellular membranes in all tissues examined . These gene products have been isolated from cells associated with subcellular membranes . These membranes have been assayed both for their antigen content (antigenicity) and for their capacities to induce a primary humoral and a cell-mediated response (immunogenicity) . In all tissues examined, the H-2 antigens (products of the K and D regions of H-2) were found expressed in high concentration on cell surface membrane . However, immunogenic activity was observed only with spleen and thymus preparations, consisting mainly of intracellular membranes (MLP) . Immunogenic MLP was also isolated from lymphoblast and fibroblast cells, and again was derived mainly from endoplasmic reticulum . In other tissues, such as liver, kidney, and erythrocytes, H-2 antigens were found only on surface membrane and in an antigenic but nonimmunogenic form . A novel method for tagging surface membrane of mammalian cells is presented . It consists of binding, to whole cells in a covalent linkage, purified preparations of the beta-galactosidase of E . coli . The bound enzyme has proved to be an unambiguous marker for surface membrane . With this marker, the stability of surface membrane to shear forces during homogenization could be assessed . A number of considerations suggest that immunogenicity of transplantation antigens may be due to factor(s) present on the membranes in addition to the H-2 antigenic determinants . There are indications that these factors may be controlled by the I region of the H-2 complex . It is interesting to note that normal tissues which have Ia antigens on their surface membranes yield immunogenic MLP (spleen and thymus), whereas those without Ia surface antigens yield an antigenic MLP that has no immunogenic capacity (liver, kidney, and erythrocytes).

Ann N Y Acad Sci, 1976, 274, 461 - 7
Myasthenia gravis: the role of immunological deficiency; Dawkins RL et al.; To evaluate further the association between myasthenia gravis and humoral immune deficiency, 92 sera from myasthenic patients were tested so as to determine titers against commensal E . coli, isohemagglutinin titers, and IgG and IgM concentrations . Results were compared with those obtained from normals, disease controls, and W27 positive arthropathy . On the basis of these three investigations it is concluded that subtle immunodeficiency is common in myasthenia gravis, and it is suggested that an immune defect might explain such diverse associations as thymic disease, HL-A antigens, and various autoimmune phenomena.

Zentralbl Gynakol, 1976, 98(12), 751 - 2
{Problem of the relationship between pyelonephritis in pregnancy and ABO blood-group system}; Gunther M et al.; In the present publication the attempt is made to show relationship between pyelonephritis and blood-group . A shift of the blood-group distribution in disfavour of blood-group O can be seen finding its expression especialy in the representation of the relationship between E . coli demonstration and blood groups.

Mol Biol (Mosk), 1976 Jan-Feb, 10(1), 89 - 98
{Inhibiting effect of S-adenosyl-L-homocysteine and its structural analogs on the process of enzymatic methylation of tRNA}; Kogan MV et al.; The action of S-adenosyl-l-homocysteine (S-Ado-Hcy), its four structural analogues S-Ino-Hcy, S-Guo-Hcy, S-Urd-Hcy, S-Cyd-Hcy and the five corresponding sulfoxides on tRNA methylases has been investigated . The data obtained in the study of overall incorporation of 14CH3-groups into an unfractioned tRNA preparation suggested that both the affinity of the inhibitors tested for various methylases and the type of inhibition were different . The experiments performed with unfractioned tRNA preparation permit to get an idea of the average inhibitory potency of each of the compounds . The study of their action on individual tRNA methylases by means of fractionation of minor components produced demonstrated that the affinity of the inhibitors tested for various methylases was really different . Thus, S-Ado-Hcy, S-Ino-Hcy and S-Urd-Hcy practically do not inhibit m1A methylase but have the highest affinity for m5C methylase . In an experiment with tRNAPhe which is a substrate for a single, namely m5C methylase, the type of inhibition of this methylase by S-Cyd-Hcy was revealed; it was found to be non-competitive with respect to S-Ado-Met, and the S-Cyd-Hcy concentration reducing the methylation by 50 percent was 1.2-10(-4) M.

Mol Biol (Mosk), 1976 Jan-Feb, 10(1), 3 - 34
{Chromosome structure, histones and gene activity in Drosophila}; Khesin RB et al.; The problem to be reviewed in this study concerns the mechanism of regulation of gene activity relied on the structural changes of the chromatin . The role of histones in the regulation of transcription is discussed on the basis of the results obtained by the authors and literature data . In particular, the results are presented of the investigations of decrease of the histone amount in the cell nucleus using the deficiency of histone structural genes . This leads both to the increase of the X-chromosome template activity and the inhibition of variegated position effect . The latter is also inhibited by feeding of larvae with T2-DNA . It is supposed that the chromatin structure is a mechanism of epigenetic changes and the gene inactivation due to the position effect inherited in cell lineages in an example of such epigenetic changes.

Mol Biol (Mosk), 1976 Jan-Feb, 10(1), 216 - 23
{Catabolyte repression of Escherichia coli K12 mutants with defects in different systems of glucose transport}; Gershanovich VN et al.; The phenomenon of glucose catabolite repression was studied in E . coli mutants inable to transport this carbohydrate . The pts 1, H mutant P34 was much less sensitive to the repressive effect of glucose on beta-galactosidase synthesis than the parent type . The 1103 mutant devoid of enzyme 1 of the phosphoenolpyruvate-dependent phosphotransferase system (PTS) behaves in the same way as P34 mutant after addition of glucose to casamino acid mineral medium . However, in minimal medium with succinate as the sole source of carbon, cells of the 1103 mutant show enhanced sensibility to transient glucose repression . The effect of hypersensibility disappears when the lac I mutation leading to constitutive the beta-galactosidase synthesis is introduced in 1103 mutant . It is shown that the enhanced sensibility of beta-galactosidase synthesis to glucose transient repression in 1103 mutant is an effect of the aburpt decrease in its growth rate in the presence of succinate and most probably this decrease leads to "inducer exclusion" of the lac operon . It is also shown that if one introduces the P34 mutation in strain JD3 devoid of one of the enzymes II for glucose (and due to this resistant to glucose catabolite respression) then the level of resistance in double mutant does not increase in spite of considerable supression of 14C glucose accumulation . In connection with this the role is discussed of separate components of the E . coli K 12 glucose transport system in realization of the phenomenon of catabolite repression.

Genetika, 1976, 12(4), 100 - 8
{Genetic control of the RecF recombination pathway . II . Effect of recL- and uvrE- mutations}; Smirnov GB et al.; It was found earlier that the effect of the uvrE- mutation on the yield of recombinants formed via RecF pathway of recombination was mainly due to the decreased viability of the recB-C-sbcB-uvrE- recipient . The results of the present paper show the uvrE- and recL- mutations reduce the recipient ability of the recB-C- sbcB- strains to the same extent . We were unable to find any evidence for complementation between the recL- and uvrE- mutations in transient as well as in stable uvrE-/recL- merozygotes . The recL152 as well as the uvrE502 mutation is lethal for the strains deficient in DNA polymerase I . Both recL- and uvrE- mutations reduce in the recB-C- sbcB- strains the probability of inheritance of the proximal non-selective donor markers as well as selective markers located close to the leading end of the donor chromosome . The former effect however could not be completely due to the latter.

Biochimie, 1976, 58(6), 663 - 75
{Transaminase B from Escherichia coli . I.-Purification and first properties}; Monnier N et al.; Transaminase B (EC.2.6.1.6.) from E . coli, the specific enzyme for branched-chain aminoacids, was obtained in a purity equal to or greater than 96 p . cent after an 800-fold purification, employing two different procedures . One of the procedures involved heating at 60degreesC . The apparent molecular weight of the enzyme was estimated by chromatography on Sephadex and gel electrophoresis to be close to 180,000 . The protein is made up of 6 subunits of equal size, with one molecule of coenzyme in each . Its absorption spectrum shows bands at 335 and 415 nm, and was found to be almost insensitive to the pH of the medium between 4.6 and 9 . Transaminase B is active on phenylalanine as well, although the reaction between L-phenylalanine and alpha-ketoglutarate is about 50 to 100 times slower than the analogous reaction using L-valine as an aminoacid . Three sets of data show that the phenylalanine aminotransferase activity associated with transaminase B is not an artefact due to a protein contaminant . 1) Activities displayed toward phenylalanine and valine cannot be resolved by different methods, including chromatography, gel electrophoresis, and electrofucussing . 2) The absorption spectrum of the enzyme is as strongly modified by phenylalanine as by valine . 3) A ketoglutarate-free reaction between phenylalanine, tyrosine or typtophane and an aliphatic alpha-ketoacid is catalyzed by the pure enzyme and follows a mechanism belonging to the usual ping pong type . The possible significance of this reaction as a regulatory device in the cell metabolism is briefly discussed.

Biochimie, 1976, 58(6), 629 - 45
The methylation of tRNA; Nau F; The methylation of tRNA is a post-transcriptional modification which is achieved by specific enzymes, the tRNA methylases, with S adenosylmethionine as a methyl donor . The level and pattern of methylation are characteristic of the tRNA species and origin . Abnormally methylated tRNAs have been obtained, in vivo and in vitro, by a variety of methods, and their properties have been studied . The tRNA methylases are found in all cells and tissues . Their activity varies with the differentiation state of the cells, and under the influence of many internal and external factors ; it is especially elevated in embryonic and cancerous tissues . These enzymes are very unstable, and none of them has been purified to homogeneity . We present here their known properties and we propose a theory concerning their specificity . Finally, after reviewing the few available experimental data, we discuss the current hypotheses and speculations about the roles and functions of tRNA methylation.

Biochimie, 1976, 58(1-2), 81 - 5
The periplasmic galactose receptor protein of Escherichia coli in relation to galactose chemotaxis; Kalckar HM; The periplasmic galactose receptor protein of E . coli is the common macromolecule in the initiation of two functions, chemotaxis and active transport . The substrates are glucose and galactose and the affinity for binding to the receptor protein is high (Kp -2 X 10(-8) M for glucose and 1 X 10(-7) M for galactose) . A second binding site shows a 100-fold lower affinity . The high concentration of the galactose receptor protein in the periplasmic space tends to give retention through recapture of the ligands . The kinetic properties of the galactose receptor protein are, in general, in harmomy with the kinetics of chemotactic responses to spatial or temporal sugar gradients.

Biochimie, 1976, 58(1-2), 233 - 8
{Escherichia coli K12 mutant with increased RNA content and messenger RNA stability}; Liebart JC et al.; A strain of Escherichia coli has been isolated from a E . coli HfrH after a treatment with nitrosoguanidine for a partial resistance to thymineless death . This strain shows, in addition, a global increase of the RNA content amounting to 50 per cent . The half-life of the unstable RNA as well as of the messenger RNA of the beta-galactosidase is increased to a considerable degree . The RNA polymerase of this strain is modified with respect to its resistance to rifampicin and its transcription efficiency in vitro of various DNA templates . Our working hypothesis is that the primary alteration of this strain lies at the RNA polymerase level with a consequent increase of the synthetic rate of the ribosomal RNA . The increase of the messenger RNA half-life may be an indirect consequence of this event via a saturation of the RNAase by the excess of ribosomal RNAs not associated to their proteins.

Biochimie, 1976, 58(1-2), 201 - 5
{New studies on inhibition of tRNA N2 guanine methyltransferase by S-adenosyl-homocysteine and S-adenosyl-methionine analogs}; Michelot R et al.; New structural analogs of S-adenosyl homocysteine (SAH) 1-9, 11-14, 19-21) and of S-adenosyl methionine (15-18) have been tested as inhibitors of a N-2 guanine methyltransferase extract from rabbit liver with E . coli B tRNA as substrate . The sulfonium compounds (mixture of +/- diastereoisomers) are more inhibitory than the sulfide derivatives but less inhibitory than SAH itself . The replacement of the aminoacid chain in SAH by various alphatic radicals leads to a correlation between their bulk and the size of the enzymatic site . The monosubstitution of N-6 amino group does not affect significantly the inhibitory effect, which is completely canceled by the disubstitution of N-6.

Adv Exp Med Biol, 1976, 69, 349 - 70
Energetics of low affinity amino acid transport into brain slices; Banay-Schwartz M et al.; It appears possible to dissect and study some of the potential energy sources for amino acid transport in brain slices despite the apparent complexity of the tissue in comparison to that of isolated bacterial vesicles23 . The uptake capability of the tissue may be inadvertently damaged in some experimental protocols so that very special controls must be used to ensure that the treatment did not somehow inactivate the very mechanism that thereafter will be tested . We have presented some evidence that brain slice amino acid transport may not be obligatorily linked to glycolysis, ATP levels, Na+, K+-ATPase activity, K+ levels or direction of flux, or to Na+ flux . However, the energy source linkage for different amino acids appears to be rather specific, so that further generalizations are difficult to sustain . For instance, the incubation media and conditions we describe here were experimentally adjusted to maximize uptake of D-glu or alpha-AIB in the absence of glucose, or in lowered K+ or Na+ . Therefore, these procedures, the results of which directly challenge some common assumptions regarding the energy basis for active transport in brain slices, probably will not be universally extensible to all other actively transported amino acids.

Mikrobiologiia, 1976 Jan-Feb, 45(1), 151 - 6
{Mutagenesis of synchronous populations of Escherichia coli with normal and defective reparative enzymes under the influence of hydroxylamine}; Soifer VN et al.; Bacterial populations of E . coli K12 uvr+ and E . coli K12 uvr- were preliminary synchronized on membrane nitrocellulose filtres and then treated with 1 M hydroxylamine for different times; the frequency of mutants failing to assimilate glucose was estimated . Kinetics of mutagenesis in the cells of both strains was almost the same and indicated that lesions induced by hydroxylamine were not repaired . It is for the first time that the maximum mutation frequency was registered in experiments with hydroxylamine; this suggests that the repair hypothesis of attaining the maximum mutation frequency is not universal.

Folia Microbiol (Praha), 1976, 21(3), 161 - 7
The effect of substitution of diaminopimelic acid by 4-hydroxy-diaminopimelic acid on the synthesis and degradation of murein in Escherichia coli 173-25; Chaloupka J et al.; Defects in the formation of the septum and gradually autolysis of cells occur when the dap-dependent mutant of Escherichia coli is grown in a medium with 4-hydroxy-diaminopimelic acid . When the culture grown in the presence of the labelled analogue is supplemented with the non-radioactive diaminopimelic acid a portion of the TCA-soluble radioactivity is released from the cells during 20 min after the addition of diaminopimelic acid . During this time interval the elongated forms formed in the presence of the analogue divide, however, only on the condition that the above forms are not irreversibly damaged . The increased concentration of the analogue in the medium substantially suppresses the irregularities in the development of the septum as well as the degradation of analogue containing cell wall . However, the growth rate in the presence of the analogue is always slightly lower than that in the presence of diaminopimelic acid . The cell wall pulse-labelled with diaminopimelic acid or its analogue for a time interval shorter than 1/4 of the generation time exhibits the same or only slightly higher rate of diaminopimelic acid is probably utilized less effectively for the synthesis of murein than diaminopimelic acid . However, its incorporation into the wall does not result in pronounced damage of the cell.

Folia Microbiol (Praha), 1976, 21(2), 90 - 9
Role of post-replication and excision repair mechanism in the induction of Trp+ revertants of UV-irradiated Escherichia coli; Balgavy P et al.; Both the post-replication and the excision repair mechanism participate in the induction of Trp+ revertants in Escherichia coli B/r Hcr+ thy trp after a UV-irradiation . At low radiation doses (surviving cell fraction greater than 10(-1) most Trp+ reversions are due to post-replication repair mechanism while at high doses (surviving cell fraction less than 10(-1)) the Trp+ reversions arise probably as the result of an inaccurate excision repair . The absolute accuracy of repair processes decreases with increasing radiation dose.

Acta Microbiol Pol A, 1976, 8(1), 35 - 42
Transformation of Escherichia coli by R404 factor DNA and properties of the transformants; Kurowska E et al.; Three r-determinants (Cb Cm Cf) out of eight present in R404 factor were transferred in transformation of Escherichia coli by the plasmid DNA isolated from minicells . The r-determinants acquired in this way formed the replicon tr404-1 and were untransferable by conjugation unless another self-transmissible plasmid was present in recipient . The evidences are presented in support of hypothesis that the transfer events consist in infection of transformant cells with sex factor, recombination between tr404-1 replicon and the sex factor and finally transfer of the new formed structure to the host cells of the sex factor.

Acta Microbiol Pol A, 1976, 8(1), 17 - 26
Segregation of Col Ib and drd7 into minicells; Skorupska A et al.; The wild-type plasmid ColIb and its mutant drd7 derepressed in conjugation were transferred to Escherichia coli K12 P678-54 which produces minicells . Fertility functions of drd7 remained derepressed in the new host . P678-54drd7 transmitted the plasmid at a high frequency (28.6%) and it was effectively lysed by the phage If1 . Significant amounts of 3H-DNA segregated from P67854Col+ into minicells dependent upon the presence of the plasmid . The depressed plasmid segregated more effectively into minicells than the wild-type plasmid . ColIb segregated into 2% whereas ColIbdrd7 into 8.4% of minicells . The difference in the frequency of segregation of the wild-type and the derepressed plasmid indicated different cell membrane attachment sites of each plasmid studied . Mini-drd7 were able to transfer the plasmid to E . coli Row at a low frequency (0.1%) . Minicells carrying either of plasmid were capable to synthesize RNA and protein . RNA and protein synthesis were plasmid specific and the precursors were not incorporated into minicells without plasmids . Rifampin and chloramphenicol inhibited RNA and protein synthesis in minicells, respectively . The more effective incorporation of 3H-uridine or 14C-leucine into minicells harboring drd7 than ColIb resulted presumably from the high efficiency of the segregation of drd7 into minicells . Polyacrylamide gel electrophoresis of 3H-RNA has shown that plasmids in minicells were able to code low molecular RNA of 4s . No 16 or 23 ribosomal RNA was found in the profiles of de novo synthesized RNA in minicells.

Acta Microbiol Acad Sci Hung, 1976, 23(1), 69 - 76
Demonstration of adenovirus associated endonuclease; Medveczky P et al.; In HEp-2 and amnion cell cultures infected with type 1 adenovirus the DNase activity of cell extracts was measured on 32P-labelled Escherichia coli DNA substrate . Enzyme activity was demonstrated by the acid soluble nucleotides released from the 32P-DNA and by the decreased sedimentation rate of labelled DNA . High DNase activity was measured in both adenovirus infected and in untreated HEp-2 cell extracts . Nuclease activity of the amnion host cells being much lower than that of HEp-2 cells, virus-associated endonuclease activity was successfully demonstrated in them . Purified type 1 adenovirus decreased the sedimentation rate of 32P-labelled E . coli DNA . The phenomenon is explained by the virion-associated endonuclease activity . Trypsin inactivated and anti HEp-2 IgG failed to inhibit the virion nuclease . An association between endonuclease and trypsin sensitive penton is assumed.

Nephron, 1976, 17(1), 8 - 19
The role of vesico-ureteric (V-U) reflux in the pathogenesis of kidney scars in the rat; Morgan M et al.; In Wistar rats V-U reflux with distilled water and sterile saline of varying osmolar strength produces scars in the perihilar region of the kidneys in 80% of animals . Using Indian ink as a marker, rupture of the forniceal epithelium regularly followed V-U reflux . Intrapelvic pressure rose to 120 mm Hg during the reflux procedure . A slowing of proximal tubular transit time was observed by the Lissamine Green technique in the nephrons in the perihilar region immediately after the kidney had been subjected to reflux . It is suggested that the kidney scars which develop after reflux of sterile solutions are ischaemic in origin . It was shown that kidneys damaged by reflux have an increased susceptibility to haematogenous infection.

J Supramol Struct, 1976, 4(4), 449 - 65
Conjugated polyene fatty acids as fluorescent membrane probes: model system studies; Sklar LA et al.; The use of conjugated polyene fatty acids as probes of membrane structure is examined, alpha- and beta-parinaric acid (cis, trans, trans, cis- and all trans-9, 11, 13, 15-octadecatetraenoic acid) and synthetic lecithins containing an alpha-parinaric acid chai in position 2 have been prepared, and their absorption and fluorescence properties have been determined . Their absorption spectra are at sufficiently long wavelength to be unobscured by cellular chromophores such as nucleotides and aromatic amin acids . Parinaric acid absorption does, however, overlap tryptophan emission which allows fluorescence energy transfer . Potential uses of these fluorescent probes are presented with studies on mode systems with known physical properties . Dipalmitoyl phosphatidylcholine exhibits a sharp phase transition 1 degree wide at 42 degrees C, as monitored by the fluorescence intensit of parinaric acid . The magnitude of the transition is independent of probe concentration, but the width of the transition and hysteresis are dependent upon such factors as the probe concentration and whether or not sonication is used in sample preparation . Using both fluorescence and absorption properties of the probe, we show that the addition of cholesterol to the dispersion broadens and decreases the magnitude of the transition . These results are interpreted in terms of a change in the polarizability of the acyl chains of a lipid bilayer undergoes a thermal transition . Lipid-protein interactions are studied by the binding of alpha-parinaric acid to bovine serum albumin . Fluorescence enhancement, absorption spectral shifts, and quenching of tryptophan fluorescnece are observed when alpha-parinaric acid binds to bovine serum albumin . Calculations based on these measurements are consistent with two binding sites of KB approximately 10(8) (M-1) and three to four binding sites of KB approximately 10(6)-10(7) (M-1), similar to known values for the binding of other long-chain fatty acids . Biosynthetic incorporation of beta-parinaric acid into the E . coli fatty acid auxotroph 30E betaox has been accomplished and phase transitions in cells and isolated phospholipids are shown.

Ann Microbiol (Paris), 1976 Jan, 127A(1), 131 - 42
The multipartite genome of brome mosaic virus: aspects of in vitro translation and RNA structure; Davies JW; The multipartite nature of the brome mosaic virus genome is described . Particular attention is given to the translation of the RNAs in cell-free extracts, from dry wheat seed embryos and commercial wheat germ . Such studies have demonstrated that the smallest RNA is a monocistronic message for coat protein . This cistron is also carried on the intermediate sized RNA, which also codes for a larger protein, of unknown function . Translation of the larger RNAs 1 and 2 is compared, incell-free extracts of wheat embryo and wheat germ . There is evidence that these RNAs may also be monocistronic messages for large polypeptides (molecular weight 100,000), indicating that there are few non-translatable regions on these RNAs . Some recent nucleotide sequence studies are described, including the ribosome binding site of the coat protein cistron, and the 3' termini of all four RNAs, which appear to be identical, at least over a region of 150 nucleotides.

Genetika, 1976, 12(1), 98 - 110
{Revertants of recA-strains of Escherichia coli K-12}; Shishkova OV et al.; The paper presents the results of a study of revertants of strains AB2463 recA13, AB2465 rec15, No 41 rec16 . It is shown that revertants are characterized as intermediate strains between recA and rec+ (on the level of recB, recC strains) on their recombination proficiency in crosses with Hfr, sensitivity to UV and gamma-rays and in F-heterogenote formed cultures on their capacity of the formation of recombinants between episome and chromosome and the capacity to chromosome mobilization . In the same time revertants do not differ from rec+ in the frequency of spontaneous and UV-induction of prophage constitution of recombinants formed in crosses, and in the synthesis of beta-galactosidase in postconjugation period . It is found that the mutations studied are mapped apparently in recA gene.

Adv Exp Med Biol, 1976, 66, 95 - 9
Cell selection in the thymus of mice treated with escherichia coli lipopolysaccharide (LPS); Uccini S et al.; The present data indicate that injection of LPS induces a decrease in thymus weight with selection of thymocytes more efficient in killer and helper activities . It has been reported (12) that two T-cell types may cooperate in the GVH reaction: the effector T1 and the amplifier T2 . The maturation from T1 to T2 occurs mainly in the periphery, whereas immature cortex thymocytes differentiate to T1 within the thymus (13) . Our results, showing an LPS-dependent enhancement of thymocyte killing activity, suggest that LPS selects thymocytes mostly of the T1 type . LPS-treated thymocytes are more efficient in the reconstitution of the anti-SRBC response . These data can be explained considering that LPS, like cortisone (14), enriches the thymus with more immunocompetent helper cells . Alternatively it may be suggested that LPS selects in the thymus cell populations characterized by high proliferative activity . Unpublished observations showing that LPS-treatment in vivo increases the in vitro response of thymocytes to Con-A are consistent with this interpretation.

Dev Biol Stand, 1976, 31, 230 - 4
{Mitogenic activity of Brucella fractions on cultured lymphocytes}; Renoux M et al.; LPS from smooth B . melitensis extracted by the phenol-water method has no mitogenic activity for lymphocytes of men or mice uninfected by brucellosis, in amounts that are not toxic in vitro for these cells . Mitogenic activities of other B . melitensis fractions are evidenced only in amounts 100-fold greater than an effective dose of LPS from E . coli . We interpret these findings as reflecting a virgin immune status against brucella antigens.

Biochem J, 1976 Jan 1, 153(1), 55 - 62
Substrate-binding ability of Escherichia coli ribonucleic acid polymerase in relation to its protein composition; Rognes A et al.; Interaction between Escherichia coli RNA polymerase and its substrates, the nucleoside triphosphates, was studied by gel-filtration and dialysis-rate-measurement techniques . 2 . The holoenzyme bound variable amounts of ATP and GTP . There was no correlation between substrate-binding ability and enzyme activity of different enzyme preparations . 3 . The core enzyme bound a maximum of 0.1 mol of ATP/mol of enzyme . The dissociation constant of this interaction was of the order of 1 X 10(-5)M . The core enzyme did not bind GTP . 4 . A protein of mol.wt . 60000, which was eluted in the first fraction during phosphocellulose column chromatography of the holoenzyme, bound appreciable amounts of ATP . The dissociation constant of this interaction was of the order of 3 X 10(-5)-5 X 10(-6)M . 5 . Evidence presented shows that this protein, and not the sigma factor, is responsible for the observed variation in the ATP-binding ability of the holoenzyme.

Nucleic Acids Res, 1976 Jan, 3(1), 101 - 16
Terminal labeling and addition of homopolymer tracts to duplex DNA fragments by terminal deoxynucleotidyl transferase; Roychoudhury R et al.; Terminal deoxynucleotidyl transferase, which requires a single-stranded DNA primer under the usual assay conditions, can be made to accept double-stranded DNA as primer for the addition of either rNMP or dNMP, if Mg+2 ion is replaced by Co+2 ion . The priming efficiency in the presence of (C leads to) CO+2 ion with respect to initial rate tested with 2 single-stranded primer, is 5-6 fols higher than that observed with Mg+2 ion . In the presence of Co+2 ion, the primer specificity is altered so that all forms of duplex DNA molecules can be labeled at their unique 3' -ends regardless of whether such ends are staggered or even . Thus, using ribonucleotide incorporation, we have for the first time employed this reaction for sequence analysis of duplex DNA fragments generated by restriction endonuclease cleavages . Furthermore, by using Co+2 ion, it is possible to add a long homopolymer tract of deoxyribonucleotides to the 3'-terminus of double-stranded DNA . Therefore, without prior treatment with lambda exonuclease to expose the 3' terminus as single-stranded primer, this reaction now permits insertion of homopolymer tails at the 3'-ends of all types of DNA molecules for the purpose of in vitro construction of recombinant DNA.

Nucleic Acids Res, 1976 Jan, 3(1), 1 - 10
Interactions between 30s ribosomal proteins and 50s subunits of Escherichia coli; Jenness D et al.; The interaction between ribosomal proteins of the 30s subunit with intact 50s subunits was investigated . Experiments with mixtures of total 30s proteins indicated that several 30s proteins including protein s4 would form a stable complex with 50s subunits . Further work with pure s4 indicates that this protein binds stoichiometrically to the 50s subunits, probably through protein-nucleic acid interaction . The possible significance of this interaction is discussed.

Nord Vet Med, 1976 Jan, 28(1), 19 - 32
{The K antigens of Escherichia coli (author's transl)}; Soderlind O; The development of the serology of Escherichia coli, especially the present division of the antigen into L, B, and A antigens is described . Only the A antigen should be regarded as a capsular antigen whereas L and B antigens are to be considered as envelope antigens . Immunoelectrophoretic studies by Orskov & Orskov (1972) on the K antigens and O antigens of Escherichia coli revealed that the strains could be placed into a few well defined groups according to migration patterns of the O antigens and of the thermostable polysaccharide K antigens . Orskov's et al proposed new criteria for K antigens and studies on the importance of K antigens as determinants of virulence in Escherichia coli are presented

Infect Immun, 1976 Jan, 13(1), 100 - 7
Experimental neonatal colibacillosis in cows: immunoglobin classes involved in protection; Wilson RA et al.; Pregnant cows were vaccinated with one of four vaccine preparations to induce passive immunity in their offspring against a homologous oral challenge with Escherichia coli strain B-44 . Quantitative assays of specific antibody in colostral whey from both immunized and nonimmunized dams revealed that immunoglobulin G, immunoglobulin A (IgA), and immunoglobulin M (IgM) with anti-O (somatic) activity were present in whey of all dams tested, whereas a marked deficiency of IgA and IgM anti-K immunoglobulin was noted in the whey from control dams only . The degree of scours (neonatal colibacillosis) induced by oral challenge was evaluated clinically and reported by a semiquantitative scour index as 0 to 4+ . Calf scour indexes showed an inverse relationship to the frequency of occurrence and to the levels of IgA and IgM in whey of dams vaccinated with killed vaccine, live vaccine, and culture supernatant, and from nonvaccinated controls . The data strongly suggested that IgA and colostral IgM anti-K immunoglobulins were important in passive immunity in experimental neonatal bovine colibacillosis.

Immunology, 1976 Jan, 30(1), 49 - 57
Antibody formation in mouse bone marrow . V . The response to the thymus-independent antigen Ecsherichia coli lipopolysaccharide; Benner R et al.; The occurrence of plaque-forming cells (PFC) in mouse bone marrow was studied during primary and secondary responses to the thymus-independent antigen Escherichia coli lipopolysaccharide (LPS) . Anti-LPS responses were induced by various doses of LPS . During the primary response, doses of 1 and 10 mug LPS intravenously (i.v.) were found to evoke a distinct PFC response in both spleen and bone marrow . The spleen contained the majority of PFC until about 5 days after immunization . During the course of the reaction the number of PFC in the bone marrow rose to a level which equalled or surpassed the level in the spleen . LPS doses of 0-001, 0-01 and 0-1 mug i.v . only induced a PFC response in the spleen . Apparently there is a minimal threshold dose of LPS of about 1 mug for PFC to appear in the bone marrow . The secondary response was studied in mice primed with 1 mug LPS i.v . and boosted with either 0-001, 0-1 or 10 mug LPS i.v . 3 months later . After each dose tested the PFC activity in the spleen was several times higher than during the primary response . As was observed in the primary response doses of 0-001 and 0-1 mug LPS i.v . did not evoke a PFC response in the bone marrow . After boosting with 10 mug of LPS i.v . a significant PFC response was found in spleen, bone marrow, thymus, lymph nodes, Peyer's patches and blood . From about 5 days after the booster injection the number of PFC in the bone marrow exceeded the total number found in all other lymphoid organs . The results are discussed in relation to the bone marrow PFC response to the thymus-dependent antigen sheep red blood cells . To this antigen a clear PFC response in the bone marrow is found only during the secondary response.

Hoppe Seylers Z Physiol Chem, 1976 Jan, 357(1), 21 - 33
Lipid-lipid and lipid-protein interactions as studied with a novel type of fluorescent fatty acid and phospholipid probes; Stoffel W et al.; A novel fluorescent-labelled group of fatty acids and phospholipids has been applied to determine phase transitions in liposomes by fluorescence intensity and polarisation measurements . The chromophore of these amphiphilic lipids proved to be very suitable to demonstrate temperature-dependent lipid-lipid interactions . Liposomes from 1,2-dipalmitoyl-3-sn-glycero-phosphoethanolamine and from lipids isolated from membranes of E . coli K 1062 mutant grown on elaidic acid were used in these studies . These probes also made it possible to observe conformational changes in membrane proteins in isolated plasma membranes from this mutant . The changes in protein conformation were dependent on structural changes in the lipid phase.

Folia Microbiol (Praha), 1976, 21(1), 1 - 9
Elimination of lethal and pre-mutational DNA lesions during the photoreactivation of UV-irradiated Escherichia coli; Balgavy P et al.; The comparison of the frequency of trp+ revertants of Escherichia coli B/r Hcr+ thy trp after UV-irradiation on the one hand and after UV-irradiation plus photoreactivation on the other showed that both photoreversible pyrimidine dimers of the cyclobutane type and the non-photoreversible DNA lesions cause, at equal lethal effects, also trp+ reversions with the same efficiency . If lethal, the pyrimidine dimers may thus be conceived as primary pre-mutational lesions.

Clin Nephrol, 1976 Jan, 5(1), 20 - 4
Infantile nephrotic syndrome; George CR et al.; The clinical features and renal histology of twelve chinldren who developed nephrotic syndrome in the first year of life were studied . Six suffered from microcystic disease and six from primary mesangial cell proliferation and/or sclerosis . A consistent family history, premature birth, large placenta pressence of other congenital abnormalities, onset in the first two months of life and lower plasma albumin level all suggested microcyste disease, but the most reliable distinction was histological . All microcystic children died within two years, whereas four with primary mesangial disease survived indefinitely . Corticosterid and immunosuppressive herapy failed to help either group and most deaths were due to sepsis, especialy with E . coli.

Chem Biol Interact, 1976 Jan, 12(1), 91 - 8
Adaptation of the cells of Escherichia coli to the presence of hydroxyurea increases the level of inorganic pyrophosphatase acttivity; Heinonen J et al.; Hydroxyurea, an inhibitor of ribonucleoside diphosphate reductase, completely arrested the net synthesis of DNA for 3-4 h, when it was added in 30 mM concentration to growing cultures of Escherichia coli K12 . Thereafter the net synthesis of DNA started again, although slowly, and simultaneously with it the formation of inorganic pyrophosphatase activity was stimulated leading to a 2-fold increase in the specific activity of the enzyme in 2-3 h . Subsequently cell division began again . In this way a new steady state, stable in the presence of hydroxyurea, was reached . This new state was characterized by the high specific activity of inorganic pyrophosphatase, a small but constant amount of DNA/cell mass (1/4 of the normal value), and large elongated cells . All these changes were slowly reversed during 5-6 h, when the cells were transferred into a drug-free medium . The activity of isoleucyl-tRNA synthetase, assayed as a control, did not change significantly in the presence of hydroxyurea . Hydroxyurea had no effect on the activity of inorganic pyrophosphatase in vitro.

Microbios, 1976, 16(65-66), 207 - 18
Detection of precursors of quinolinic acid in Escherichia coli; Chen J et al.; A technique is described which allows the detection of precursors of quinolinic acid produced by Escherichia coli, independent of a bioassay . This is based on a double autoradiogram utilizing radioactive aspartic acid and fructose-1,6-diphosphate (as a source of dihydroxyacetone phosphate) . Six radioactive spots are derived from aspartic acid and four are derived from fructose-1,6-diphosphate . The latter four spots correspond to four of the former spots in migration in each of two solvent systems . The significance of these data relative to genetic and enzymatic data is discussed.

Genetika, 1976, 12(7), 180 - 2
{Effect of 2,6-diaminopurine resistance mutations on adenine and adenosine assimilation by cells of an adenine-dependent strain of Escherichia coli K-12}; Livshits VA; In purine-requiring strain of Escherichia coli K-12 defective in purine nucleoside phosphorylase (pur, pup) mutants (designated apt) have been obtained that are resistant to 2,6-diaminopurine on guanine-containing medium and incapable to utilize adenine for their growth at 42degreesC, but they are still sensitive to the analogue and can utilize adenine at 28degreesC . It has been shown that the introduction of the corresponding apt mutations in the genome of adenine-requiring strains impaired the ability of these strains to grow on both adenine and adenosine at 42degreesC.

Biokhimiia, 1976, 41(7), 1256 - 62
{Effect of detergents and proteolytic enzymes on membrane-bound phosphohydrolases in Escherichia coli cells with repressed and depressed biosynthesis of these enzymes}; Nesmeianova MA et al.; Solubilization of protein membranes by detergents and protein liberation from the membranes induced by proteolytic enzymes results in a change of activity of membrane-bound phosphohydrolases--alkaline phosphatase and polyphosphatase . The activity of enzymes under conditions of repressed and derepressed biosynthesis of phosphohydrolases changes differently, thus indicating their different membrane environment in the two types of membranes . Some data were obtained on the localization of alkaline phosphatase in a hydrophobic region, possibly in lipid bilayer and polyphosphatase in the surface layers of the membrane.

Arch Virol, 1976, 52(3), 217 - 31
Comparative studies on the structural proteins of T3 and T7 phages; Issinger OG et al.; A comparison of the coat protein patterns of the wild types of the related phages T3 and T7 on SDS polyacrylamide gel electrophoresis was carried out . After infection of the nonpermissive host with T7 amber mutants in genes 7, 11, 12, 13 or 17 and T3 amber mutants in genes 11, 12, 13 and 17 respectively, noninfectious, DNA containing particles were produced . The protein pattern, as well as electron microscopy of defective particles of T3 and T7 led to the conclusion that the proteins specified by genes 11, 12, 13 and 17 are tail proteins whereas the proteins coded by genes 7, 8, 10, 14, 15 and 16 enter the head structure . The "serum blocking protein" (gene 17 product) seems to play a different role in the assembly of T3 and T7 tails, since T3 particles defective in gene 17 did not show any tail structure connected with the head whereas T7 particles defective in gene 17 had a tail which looked different from that of the wildtype . Treatment of wildtype particles with ammonium nitrate or sodium pyrophosphate led to morphologically abberrant forms which had partially or completely lost the hexagonal head structure . After treatment with ammonium nitrate ball-like structures were obtained, both for T3 and T7 . However, in the case of T3 these abberrant forms contained the proteins specified by genes 7, 8 and 10 whereas those derived from T7 contained only the proteins specified by genes 8 and 10 . Sodium pyrophosphate treatment of T3 and T7 wildtype particles led to a release of the phage tails . The isolated tails were examined by electron microscopy thus revealing for the first time a detailed substructure of the T3 and T7 phage tails . In order to find out more about the tail proteins, absorption experiments with isolated bacterial cell walls were carried out.

Ciba Found Symp, 1976, (42), 223 - 36
The aetiology of diarrhoea in newborn infants; Bishop RF et al.; Diarrhoea is a common problem in newborn infants in hospital nurseries . In the past, sporadic diarrhoea was often attributed to dietary indiscretion by the mother, and epidemic diarrhoea was though to be caused by an unknown infectious agent . Techniques with which to locate non-cultivable viruses and untypable enteropathogenic strains of Escherichia coli allow reevaluation of the aetiology of diarrhoea in newborn infants . Preliminary results from Melbourne, Australia, suggest that most diarrhoea in newborn infants is induced by a specific infectious agent . During 1975 the agent most often identified from sporadic and epidemic diarrhoea in hospital nurseries was a reovirus-like particle ("duovirus") . Enterotoxin-producing strains of E . coli were rarely isolated . Future attempts to protect newborn infants from developing diarrhoea must be based on an accurate understanding of the aetiology of this disease.

Ciba Found Symp, 1976, (42), 109 - 27
Regulation of active ion transport in the small intestine; Field M; The epithelium of the small intestine can both actively absorb and actively secrete electrolytes and water . Secretion can be elicited in vitro by adding cyclic AMP or a stimulator of intestinal mucosal adenylate cyclase (cholera and Escherichia coli enterotoxins, prostaglandins, vasoactive intestinal peptide) or an inhibitor of cyclic AMP phosphodiesterase (theophylline) . Cyclic AMP appears to alter intestinal ion transport at two different loci: it inhibits a coupled influx process for Na+ and Cl- at the luminal border, thereby reducing active absorption of NaCl, and it also stimulates the active secretion of anion (or Na+ and anion) . A variety of evidence suggests that these two effects of cyclic AMP reside in different types of cells, the former in villus cells and the latter in crypt cells . The latter process is Na+-dependent and is inhibited by low concentrations of ouabain and ethacrynic acid . Active ion absorption in vitro can be enhanced by (1) stimulating Na+-coupled organic solute absorption with glucose, amino acids and possibly also oligo peptides; (2) reducing the HCO3- concentration and/or pH of the serosal bathing solution; and (3) introducing an alpha-adrenergic agonist . Cholera toxin-induced fluid production in vivo can be diminished by the first of these manoeuvres . The in vivo efficacies of the other two have not been evaluated.

Acta Microbiol Acad Sci Hung, 1976, 23(2), 171 - 80
Allosteric enzyme-tRNA complexes as regulators of transcription or translation; Denes G et al.; The dehydrogenase activity of chorismate mutase-prephenate dehydrogenase, the allosteric enzyme of the tyrosine biosynthetic pathway in Escherichia coli, is inhibited by tRNA . The inhibitory effect of tRNA from E . coli is specific, other RNA species or polynucleotides have no inhibitory effect or only slightly influence the activity of the enzyme . While NAD only slightly influences the inhibitory effect of tRNA from E . coli, prephenic acid at high concentrations suppresses the inhibition . In he presence of a fixed concentration of NAD and low concentration or absence of prephenic acid the inhibitory effect of tRNA is time and temperature dependent . It seems that in the presence of tRNA and low concentration of prephenate the enzyme undergoes a time and temperature dependent conformational change . This process is reversible and can be influenced by the concentration of prephenic acid, the first precursor of the tyrosine biosynthetic pathway . The possible regulatory role of allosteric enzyme-tRNA complexes is discussed.

Arch Exp Veterinarmed, 1976 Jan 1, 30(1), 59 - 73
{General adaptation syndrome (Selye) in the calf . 5 . Effect of increased glucocorticosteroid values on the phagocytosis activity of luekocytes, the function of RHS and the morphology of lymphatic organs}; Hartmann H et al.; Studies were conducted with the view to elucidating the correlations between increased glucocorticosteroid levels in the blood and the defense potential of calf organism against infectious diseases . The test animals were exposed to several substances (ACTH, cortisol, colibacteria, coliendotoxin), and even one to two days of increased 11-OHKS values were followed by marked decline in phagocytosis activity of leucocytes . In addition, RHS function was considerably reduced, after ten to thirteen days of application had elapsed, since at that point the disappearance of intravenously applied bacteria from circulating blood of test animals took place at rates which were much lower than those recorded from untreated calves . Differentiated length of stress or action (four to thirteen days) was followed by conspicuous changes in the lymphatic tissue of calf organism, with severe involution of thymus and follicular atrophy of intestine-associated lymphatic tissue having been the major findings . The results seem to suggest that rise in adrenocortical hormone level under stress may reduce potential organic defense to infection.

Ann Microbiol (Paris), 1976 Jan, 127A(1), 39 - 46
Interactions of plant viral RNAs and tRNA nucleotidyl transferase; Busto P et al.; Ribonucleic acid from TMV and BMV can accept AMP and CMP when digested with VPD . This incorporation is catalyzed by E . coli and yeast tRNA nucleotidyl transferases . Complex formation is obtained between TYMV RNA and tRNA nucleotidyl transferase in sucrose gradients while TMV and BMV RNAs failed to form a complex in the same conditions . The affinity of the enzyme for viral RNAs is lower than the affinity for tRNA as shown by complex formation on nitrocellulose filters and competition with tRNA . Coat protein from TMV particles enhances AMP and CMP incorporation onto tRNA catalyzed by the E . coli tRNA nucleotidyl transferase.

Trans R Soc Trop Med Hyg, 1976, 70(1), 54 - 6
In vitro sensitivity of Entamoeba histolytica to furazolidone and iodochlorhydroxyquin, separate and combined; Sargeaunt PG et al.; Entamoeba histolytica trophozoites isolated in Robinson's medium from faeces containing cysts, transported from India, have been tested in vitro against the drugs furazolidone, iodochlorhydroxyquin, and both drugs combined as Dependal . Results show the levels at which drug action is significant and that interaction between the drugs occurs at two concentrations.

Can J Biochem, 1976 Jan, 54(1), 22 - 6
On the monomeric structure and proposed regulatory properties of phosphoenolpyruvate carboxykinase of Escherichia coli; Krebs A et al.; Phosphoenolpyruvate carboxykinase (ATP:oxaloacetate carboxy-lyase (transphosphorylating)) (EC 4.1.1.49) has been purified to homogeneity from Escherichia coli . The enzyme shows the same molecular weight (ca . 65000) either by sedimentation equilibrium under nondenaturing conditions or by polyacrylamide gel electrophoresis in the presence of detergent, indicating that the enzyme has a monomeric structure . We have confirmed the previous observation that NADH is an inhibitor of this enzyme, but we have failed to detect the previously reported appearance of homotropic cooperativity with respect to substrate binding the presence of this inhibitor . Lack of such homotropic interactions is in harmony with our conclusion that the enzymes is a monomer . Replacement of Mg2+ by Mn2+ in the assay medium lowers the Km for phosphoenolpyruvate by an order of magnitude, but does not affect the characteristics of inhibition by NADH.

Nucleic Acids Res, 1976 Jan, 3(1), 35 - 47
A spin label study of the thermal unfolding of secondary and tertiary structure in E . colic transfer RNAs; Caron M et al.; The molecular mechanism of thermal unfolding of E . coli tRNAGlu, tRNAfMet and tRNAPhe (in 0.02M Tris-HC1, pH 7.5 . 10 MM Mg C12) has been examined by the spin-labeling technique . The rate of tumbling of the spin label has been measured as a function of temperature for ten different selectively spin-labeled tRNAs . Only spin labels at position s4U-8 were able to probe the tertiary structure . Evidences are presented which support the hypothesis that the thermal denaturation of the three species of tRNAs studied is sequential . The unfolding process occurs in three discrete stages . The first step (30 degrees-32 degrees) could either be assigned to a localized reorganization of the cold-denatured structure or to a "transient" melting, followed by the simultaneous disruption of the tertiary structure and part of the hU helix . This transition is observed even in the absence of magnesium . The second step (50 degrees-54 degrees) involves the melting of the anticodon and miniloop regions . The last step occurs above 65 degrees where the t psi c and amino acid acceptor stems, forming one continuous double helix, melt . A simple dynamic model is considered for tRNA function in protein biosynthesis.

Nucleic Acids Res, 1976 Jan, 3(1), 19 - 34
Specific spin-labeling of transfer ribonucleic acid molecules; Caron M et al.; The spin labels anhydride (ASL), bromoacetamide (BSL) and carbodiimide (CSL) were used to label selectively tRNAGlu, tRNA fMet and tRNAPhe from E . coli . The preparation and characterization of the sites of labeling of eight new spin-labeled tRNAs are described . The sites of labeling are: s2U using ASL, BSL and CLS and tRNAGlu; s4U using ASL and BSL on tRNAfMet and tRNAPhe; U-37 with CSL on tRNfMet; U-33 with CSL on tRNAPhe . The rare base X at position 47 of tRNAPhe has been acylated with a spin-labeled N-hydroxysuccinimide (HSL) . The 3'end of unfractionated tRNA molecules has been chemically modified to a morpholino spin-labeled analogue (MSL) . Their respective e.s.r . spectra are reported and discussed.

J Clin Pathol, 1976 Jan, 29(1), 46 - 9
An epidemic of diarrhoea in human neonates involving a reovirus-like agent and 'enteropathogenic' serotypes of Escherichia coli; Bishop RF et al.; During December 1974, an epidemic of diarrhoea occurred in the Royal Children's Hospital, Melbourne, in a ward caring for neonates with acute or chronic medical and surgical problems . Electron microscopy of diarrhoeal faeces revealed a reovirus-like particle ('duovirus' or 'rotavirus') known to cause acute enteritis in older children . This virus is considered to have been primarily involved in the aetiology of the epidemic . In addition, three 'enteropathogenic' serotypes of Escherichia coli were isolated from babies during the epidemic, but none produced enterotoxin when tested in ligated ileal loops of rabbits or in monolayers of Y1 adrenal cells . Further epidemics of neonatal diarrhoea must be studied using culture and electron microscopy of faeces to determine the relative importance of this virus and of E . coli in the aetiology of diarrhoea in this age-group.

Infect Immun, 1976 Jan, 13(1), 263 - 72
Characteristics of cells present in peritoneal fluids of mice injected intraperitoneally with Bordetella pertussis; Fishel CW et al.; Peritoneal fluids obtained from mice after the intraperitoneal administration of Bordetella pertussis vaccine, heated vaccine, an extract of the organisms, killed Escherichia coli, or thioglycolate medium were examined in terms of total cells and percentage that adhered to glass cover slips during 2-h incubation period . All these substances were found to increase the number of leukocytes in peritoneal fluid within 1 to 2 days after the injection . This increase appeared to be due to an influx of macrophages and polymorphonuclear leukocytes with relative proportions at a given time dependent upon the material involved in the induction of the response . The initial increases after pertussis vaccine seemed to be due mainly to an influx of monomuclear cells, whereas with E . coli neutrophils constituted the major portion of the cell population . The percentage of peritoneal cells that attached to glass was also found to be markedly reduced in preparations obtained from mice after the injection of B . pertussis or E . coli . There appeared to be differences in persistence of this phenomenon, with preparations containing the histamine-sensitizing factor being the most active in affecting adherence properties . Thus these data would suggest that the action of B . pertussis on macrophages (or precursors) and neutrophils is not expressed in terms of suppression of emigration properties, as has been reported by others for lymphocytes, but is manifested in the alteration of glass-adherence characteristics . Within experimental limitations, it is believed that macrophages are possibly more involved in terms of altered function than are the polymorphonuclear cells.

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