Escherichia coli

J Biol Chem, 1979 Nov 10, 254(21), 10803 - 10
A synthetic tyrosine suppressor tRNA gene with an altered promoter sequence . Its cloning and relative expression in vivo; Ryan MJ et al.; The total synthesis of a tyrosine suppressor tRNA gene with a modified promoter is described . The alteration involves the replacement of the four G:C base pairs immediately preceding the start point of transcription by A:T base pairs . The new sequence contains the recognition sequence for the HindIII restriction endonuclease at the transcriptional start point, thus permitting fusion of the structural gene with promoters containing independent sequence modifications . The construction, cloning, and biological activity of several recombinant DNAs containing the tRNA gene with the modified promoter are described . The expression of this gene in vivo is compared with that of both the unmodified synthetic suppressor gene and a naturally occurring tyr su3+ gene cloned onto a multicopy plasmid.

J Biol Chem, 1979 Nov 10, 254(21), 10604 - 6
Nucleotide sequence of the intercistronic region preceding the gene for RNA polymerase subunit alpha in Escherichia coli; Post LE et al.; The gene for RNA polymerase subunit alpha is a co-transcribed with several ribosomal protein genes (Jaskunas, S.R., Burgess, R.R., and Nomura, M . (1975) Proc . Natl . Acad . Sci . U.S.A . 72, 5036-5040) . The DNA sequence whicch codes for the COOH-terminal amino acids of S4 and the NH2-terminal amino acids of alpha, and the 25 nucleotide intercistronic sequence have been determined . This short distance supports the idea that some post-transcriptional regulation determines the differential synthesis of alpha and ribosomal proteins.

J Biol Chem, 1979 Nov 10, 254(21), 10846 - 52
Paraquat and Escherichia coli . Mechanism of production of extracellular superoxide radical; Hassan HM et al.; Paraquat mediates a superoxide dismutase-inhibitable reduction of cytochrome c by suspensions of Escherichia coli B . Glucose was most effective in providing electrons for this cytochrome c reduction, but other nutrients could serve in this capacity, provided the cells were preconditioned by growth on these nutrients . Paraquat reduction depended upon a NADPH:paraquat diaphorase, present in the cytosol . Reduced paraquat could diffuse across the cell envelope and react with dioxygen, in the suspending medium, thus generating O2- in that compartment . Most of the paraquat reduced in the cell, under the conditions used, reoxidized in situ and most of the O2- production was thus intracellular . The partitioning of reduced paraquat between intracellular and extracellular compartments, prior to reaction with dioxygen, depended upon intracellular pO2 and any strategy which raised intracellular pO2 decreased the efflux of reduced paraquat and thus decreased extracellular O2- production . Extracellular O2- and H2O2 did contribute to cell damage in proportion to the amount produced . O2- appeared to be unable to cross the cell envelope in either direction and the only O2- which was effective in raising the rate of biosynthesis of the manganese-superoxide dismutase, was that generated within the cell.

J Biol Chem, 1979 Nov 10, 254(21), 10575 - 8
Site of action of RNase I on the 50 S ribosome of Escherichia coli and the association of the enzyme with the partially degraded subunit; Raziuddin et al.; The 50 S ribosome of Escherichia coli is partially degraded by RNase I in presence of a high concentration of Mg2+ (10 to 20 mM); the partially degraded subunit becomes resistant to the further action of RNase I . The latter remains latent in association with the subparticle as in case of 30 S ribosome (Neu, H.C., and Heppel, L.A . (1954) Proc . Natl . Acad . Sci . U.S.A . 51, 1267-1274) . As a result of nucleolytic action, 23 S RNA is degraded to a smaller size and four proteins (L4, L10, L7/L12) are released from the subunit . From the location of these proteins, it appears that the primary site of action of RNase I is the central protuberance of the armchair model proposed for the subunit (Stoffler, G., and Whitman, H.G . (1977) in Molecular Mechanisms of Protein Biosynthesis (Weissbach, H., and Pestka, S., eds) pp . 117-144, Academic Press, New York).

Biochim Biophys Acta, 1979 Nov 9, 571(1), 55 - 62
Dephosphorylation of purine mononucleotides by alkaline phosphatases . Substrate specificity and inhibition patterns; Jensen MH; Three purine mononucleotides, adenosine-, inosine- and guanosine monophosphate, were used as substrates at pH 7.4 and at 10.4 for three alkaline phosphatases (orthophosphoric-monoester phosphohydrolase (acid optimum), EC 3.1.3.1) containing similar phosphate-binding serine groups at their esteratic sites . Substrate specificity was found for the enzymes from calf intestine and bovine liver . Alkaline phosphatase from Escherichia coli was nonspecific . A substrate-dependent and pronounced inhibition with the purine analogue 1,3-dimethyl xanthine was found for the enzymes from intestine and liver, but not for alkaline phosphatase from E . coli . A substrate-independent and pronounced inhibition was found for all three enzymes with the phosphomonoester p-nitrophenol phosphate as the inhibitor . Alkaline phosphatases may play an important role in the regulation of the intracellular content of purine mononucleotides.

Sem Hop, 1979 Nov 8-15, 55(37-38), 1747 - 8
{Anterior perinephritic phlegmon (author's transl)}; Loup J; A case is reported of an unsuspected anterior perinephritic phlegmon which had caused peritonitis of pyelonephritic origin thought to be due to a cholecystitis . The lesion was discovered during laparotomy and intravenous urography at operation demonstrated the condition of the underlying kidney and determined the therapeutic approach and the prognosis.

Biochem J, 1979 Nov 1, 183(2), 247 - 54
Wheat-germ aspartate transcarbamoylase . Steady-state kinetics and stereochemistry of the binding site for L-aspartate; Grayson JE et al.; 1 . The steady-state kinetics of the bisubstrate reaction catalysed by aspartate transcarbamoylase purified from wheat (Triticum vulgare)-germ have been studied at 25 degrees C, pH 8.5 AND I 0.10-0.12 . Initial-velocity and product-inhibition results are consistent with an ordered sequential mechanism in which carbamoyl phosphate is the first substrate to bind, followed by L-aspartate, and carbamoyl aspartate is the first product to leave, followed by Pi . The order of substrate addition is supported by dead-end inhibition studies using pyrophosphate and maleate as inhibitory analogues of the substrates . Product inhibition permitted a minimum value for the dissociation constant of L-aspartate from the ternary complex to be estimated . This minimum is of the same order as the dissociation constant (Ki) of succinate . 2 . A range of dicarboxy analogues of L-aspartate were tested as possible inhibitors of the enzyme . These studies suggested that L-aspartate is bound with its carboxy groups in the eclipsed configuration, and that the stereochemical constraints around the binding site are very similar to those reported for the catalytic subunit of the enzyme from Escherichia coli {Davies, Vanaman & Stark (1970) J . Biol . Chem . 245, 1175-1179}.

Cell, 1979 Nov, 18(3), 843 - 53
Nonallelic histone gene clusters of individual sea urchins (Lytechinus pictus): polarity and gene organization; Cohn RH et al.; We have analyzed the histone genes from the sea urchin Lytechinus pictus . Examination of native DNA from individuals reveals four major Eco RI restriction endonuclease histone gene DNA fragments which have been labeled A (6.0 kb), B (4.1 kb), C (3.1kb) and D (1.2 kb) . The fragments A, B and C have been cloned into E . coli plasmids (pLpA, pLpB and pLpC) . These histone gene fragments display length and sequence heterogeneity in different individuals . The plasmid pLpA contains the coding regions for H1, H4, H2B and H3 histones, and we determined that the DNA fragment D is tandem to A in native DNA and that it contains the H2A gene . The plasmids pLpB and pLpC contain the histone genes H2A-H1-H4 and H2B-H3, respectively, and together contain the sequences for the five major histones . Restriction analysis of native L . pictus DNA reveals that B and C are tandem to each other but not intermingled with the A--D-type repeat units, and are thus in separate clusters with a repeat length of 7.2 kb . Since the two cluster types do not segregate, they are not alleles . Hybridization of histone mRNA to exonuclease III-digested linear DNA demonstrated an identical polarity of the histone genes in the A--D- and B--C-type repeat units . This result revealed that the L . pictus histone genes have a polarity which is the same as other sea urchin histone genes examined to date--that is, 3' H1-H4-H2B-H3-H2A 5' . Restriction endonuclease cleavage patterns of the cloned segments indicate that considerable sequence heterogeneity exists between the two types of histone gene repeat units.

J Mol Evol, 1979 Nov, 13(4), 271 - 9
Post-maturation of the plastid ribosomal RNA in the plant kingdom; Rozier C et al.; The in vivo fragmentation of the plastid rRNA from plants situated at different places in the evolutionary sclae, with the exception of Algae, was analysed by electrophoresis using fully denaturing conditions . This fragmentation corresponds to an in vivo post-maturation . It exists only in some bacteria and is not random . Five main groups of fragments with the following real molecular weights (Mr) are found in 23 S: ca 0.9 x 10(6); 0.7 x 10(6); 0.45 x 10(6); 0.35 x 10(6) and 0.15 x 10(6) . The existence of a large fragment (Mr = 0.9 x 10(6)) corresponds to a primitive type of fragmentation found in some archaic plants . Dicotyledons and several other groups have the same pattern of 23 S fragmentation, often comprising all the fragments mentioned above, whilst Graminaceae (Monocotyledons) constitute a special group with a very predominant 0.35 x 10(6) dalton fragment and the absence of the 0.45 x 10(6) dalton fragment . The plastid 16 S rRNA in all plants studied here has a Mr of 0.54 x 10(6) which is smaller than the 16 S of Escherichia coli taken as reference (0.56 x 10(6) dalton).

Tsitol Genet, 1979 Nov-Dec, 13(6), 492 - 6
{Use of mathematical recombination models for mapping Escherichia coli K-12 markers}; Dromashko SE et al.; The possibility is discussed of mapping the E . coli K-12 markers on the basis of mathematical models of recombination previously developed by the authors . The analysis showed that it is advisable to use the symmetrical crossing-over model for mapping the genes close to the selective marker . The stochastic model of recombination gives good results also for genes located in the proximal part of the chromosome.

Mol Biol (Mosk), 1979 Nov-Dec, 13(6), 1384 - 96
{Quaternary structure of the ribosomal 30S subparticle: the model and its experimental verification}; Spirin AS et al.; In considering the structure of the ribosomal 30S subparticle from Escherichia coli we have assumed that : 1) all or almost all the proteins in the 30S subparticle are compact and globular as has been shown for isolated proteins S4, S7, S8, S15 and S16 in solution {Serdyuk I . N., Zaccai G . and Spirin A . S . (1978) FEBS Letters, 94, 349-352}; 2) RNA within the 30S subparticle has the same specific V-like or Y-like shape demonstrated for the isolated 16S RNA in a compact conformation {Vasiliev V . D., Selivanova O . M . and Koteliansky V . E . (1978) FEBS Letters, 95, 273-276} . On the basis of this assumption and numerous data published on the mutual localization of ribosomal proteins, we have constructed a model of the quaternary structure of the ribosomal 30S subparticle . We have tested the model by comparing the theoretically calculated curves of neutron and X-ray scattering at different contrasts with the corresponding experimental scattering curves of the E . coli 30S subparticles and have found that they coincide . The calculated scattering curves of several previously published three-dimensional diagrams of protein topography in the 30S subparticle do not agree with experiment.

Mol Biol (Mosk), 1979 Nov-Dec, 13(6), 1327 - 40
{Cold-sensitive mutation in the beta-subunit of Escherichia coli RNA polymerase affecting the opening of promoters}; Larionov OA et al.; A cold-sensitive mutation in Escherichia coli, affecting the beta-subunit of RNA polymerase and causing an increase in the temperature of promoter opening on T2 phage DNA, was obtained . The mutation also affects the stages preceding promoter opening by increasing the dissociation rate of RNA polymerase--DNA closed complexes . The affinity of RNA polymerase to T2- and lambda-DNA is differently changed by the mutation . The relative efficiency of transcription of these two templates is also changed . These results suggest a participation of the beta-subunit of RNA polymerase in the interaction with promoters.

Infect Immun, 1979 Nov, 26(2), 408 - 14
Prostaglandin regulation of colony-stimulating factor production by lipopolysaccharide-stimulated murine leukocytes; Moore RN et al.; The production of colony-stimulating factor by lipopolysaccharide-stimulated murine peritoneal leukocytes and their adherent subpopulations (greater than 80% macrophages) was markedly enhanced by indomethacin at concentrations sufficient to block prostaglandin E synthesis . Addition of physiological concentrations of E-series prostaglandins reversed this enhancing effect of indomethacin in a dose-dependent manner . These results indicate that colony-stimulating factor production by stimulated leukocytes is regulated by E-series prostaglandins and suggest that prostaglandins function to limit myelopoiesis by inhibiting colony-stimulating factor production and concomitantly the induction of cell proliferation.

Appl Environ Microbiol, 1979 Nov, 38(5), 956 - 64
Plasmids in Escherichia coli controlling citrate-utilizing ability; Ishiguro N et al.; The citrate-utilizing ability of 19 out of 22 citrate-positive Escherichia coli strains isolated from pig sewage was transferred via conjugation to E . coli K-12 . The conjugal transfer of citrate-utilizing (Cit) abilities was thermosensitive and concurrent with transfer of drug resistance . Weakly citrate-positive colonies were readily obtained in conjugation experiments . Their Cit characters could be transmitted to the other E . coli strains at a similar frequency in the retransfer experiments, and the transconjugants obtained still showed same characteristic growth on Simmons citrate agar plates . The 19 thermosensitive plasmids conferring citrate utilization and drug resistance were Fi-, and 16 of these plasmids belonged to incompatibility group H1 . However, occasionally two conjugative plasmids (pOH3122-1 and pOH3124-1) carrying only the citrate utilization were also obtained in the conjugation experiments, and they were Fi+ and compatible with 19 reference R plasmids . In the two citrate-positive E . coli strains, it was suggested that the conjugative Cit plasmid showing Fi+ character and the more thermosensitive H1 plasmid conferring both the Cit character and drug resistance coexisted in the strain . The characterization of citrate utilization plasmids derived from pig farm sewage is discussed.

Appl Environ Microbiol, 1979 Nov, 38(5), 911 - 5
Statistical procedure for evaluating the sensitivity of Limulus amoebocyte lysate by using a reference lysate; Rastogi SC et al.; A study was designed to estimate variability of the Limulus amoebocyte lysate test by comparing a reference lysate against itself . Three technicians performed parallel tests, i.e., titrated side by side, the contents of two vials of reference lysate on 4 different days using 24 vials of the United States reference lysate and 12 vials of the United States reference endotoxin . Each parallel test was replicated three times . From the sensitivity endpoints, ratios were calculated for each parallel test . These ratios were converted to the logarithm for estimating variability among technicians and among vials of endotoxin . By using the overall variability of log ratios, a statistical procedure was developed to evaluate the sensitivity of each lot of licensed lysate submitted to the Bureau of Biologics for release.

Can J Biochem, 1979 Nov, 57(11), 1328 - 30
Hybrid plasmids complement a putP mutation in Escherichia coli K12; Wood JM et al.; Clarke and Carbon have prepared a colony bank of 2000 Escherichia coli strains each containing a random segment of the Escherichia coli chromosome inserted into the EcoR1 restriction site of the plasmid ColE1 . We have screened the colony bank by conjugation and have identified three strains bearing hybrid plasmids that complement a defective putP gene . Each of these strains shows increased L-proline uptake activity in comparison with the unmodified host or with the host bearing noncomplementing hybrid plasmids . However, CS520, the DNA source strain employed in constructing the hybrid plasmids, is a putP mutant . Since Escherichia coli possesses two L-proline porters, a variety of possible complementation mechanisms are discussed.

J Gen Microbiol, 1979 Nov, 115(1), 89 - 94
Interrelation of DNA replication, specific growth rate and growth temperature in the sensitivity of Escherichia coli to cold shock; Gilbert P et al.; Escherichia coli W3110 was grown in a chemostat under conditions of carbon limitation at various temperatures and specific growth rates (mu) . Exponential survivor-time curves following cold osmotic shock were biphasic . These could be described by the sum of two exponential functions representing the survival of sensitive and resistant fractions of the population where the size of the sensitive fraction was directly proportional to mu . Decimal reduction times for the more resistant fraction were unaffected by mu yet decreased with increasing growth temperature . Sensitivity to cold shock was evaluated for an E . coli CR34 mutant, temperature-sensitive in initiation of DNA replication . When grown in the chemostat at the non-restrictive temperature (30 degrees C) sensitivity was directly proportional to mu . Following a rise in the incubation temperature to 42 degrees C, sensitivity decreased markedly and reached a minimum 45 to 60 min after the temperature increase . Sensitivity of the E . coli mutant grown at 30 degrees C and raised to 42 degrees C for 1 h was low and relatively unaffected by growth rate.

J Gen Microbiol, 1979 Nov, 115(1), 69 - 77
Generation time statistics of Escherichia coli B measured by synchronous culture techniques; Plank LD et al.; Synchronous cultures of Escherichia coli B were produced under various environmental conditions . Analysis of the cell number data permitted the characterization of the generation time distribution for these organisms and the estimation of the mother-daughter generation time correlation coefficients . For all growth conditions, the distribution of generation times was found to be symmetrical with a coefficienoefficient was significantly negative at doubling times between 40 and 64 min . However, the results for a culture growing in succinate medium at 37 degrees C, which had a significantly greater generation time, yielded a correlation coefficient close to zero . Within the range of temperatures studied (26 to 37 degrees C), no significant effect on the correlation coefficient was observed.

Biochem J, 1979 Nov 1, 183(2), 255 - 68
Impairment of the catalytic activity of Escherichia coli ribonucleic acid polymerase by a unique reaction of 4-chloro-7-nitrobenzofurazan; Bratcher SC et al.; Escherichia coli RNA polymerase loses 55-65% of its catalytic activity on reaction with Nbf-Cl (4-choro-7-nitrobenzofurazan) . This partial inactivation was shown to be the result of specific impairment of RNA-chain elongation, since initiation of RNA chains was not altered after treatment with Nbf-Cl . The site of reaction was shown to be a unique thiol on the beta-subunit . This thiol is not accessible to reaction with 5,5'-dithiobis-(2-nitrobenzoic acid) . No protection of the enzyme against reaction with Nbf-Cl could be obtained with the inhibitor rifamycin nor with calf thymus DNA, GTP or 1,10-phenanthroline, indicating that the unique thiol is probably not within the active site . The specific impairment of RNA-chain elongation thus appears to be the result of a local conformational change which leaves chain initiation unimpaired . Changes observed in the tryptophan fluorescence spectrum of the enzyme or reaction with Nbf-Cl are consistent with formation of a Meisenheimer complex of the reagent with a nucleophilic group on the enzyme near the reactive thiol . It is proposed that formation of such a complex and a subsequent conformational change renders this thiol unusually susceptible to reaction with Nbf-Cl.

Proc Natl Acad Sci U S A, 1979 Nov, 76(11), 5631 - 5
Detection of proteins like human gamma and beta globins in Escherichia coli carrying recombinant DNA plasmids; Wilson LB et al.; Escherichia coli strain chi 1776 carrying recombinant DNA plasmids containing cDNA copies of human beta or gamma globin mRNAs has been shown by radioimmunoassay to synthesize polypeptides antigenically related to the beta and gamma chains of human hemoglobin . The gamma and beta polypeptides have been enriched from lysates on immunoabsorbent columns containing hemoglobin antibodies and shown to specifically inhibit the antigen-antibody binding between 125I-labeled hemoglobin and the homologous antibody but not other hemoglobin-antihemoglobin reactions . Clone JW151, which is known to contain a complete copy of the coding portion of the gamma globin mRNA, has been shown to produce a protein that reacts specifically with antibody to the chain of fetal hemoglobin, hemoglobin Kenya, and hemoglobin Bart's.

Proc Natl Acad Sci U S A, 1979 Nov, 76(11), 5592 - 5
Biotinyl 5'-adenylate: corepressor role in the regulation of the biotin genes of Escherichia coli K-12; Prakash O et al.; A DNA filter-binding technique was used to study the interaction of the biotin repressor and operator site . From a biotin saturation curve, the concentration for half-maximal binding (K0.5) was calculated to be 1 microM . However, in a similar study with the in vitro coupled transcription-translation system in which biotin served as the corepressor, the K0.5 for repression was 7.1 nM . This marked difference of over 2 orders of magnitude was attributed to the activation of biotin by the partially purified repressor preparation in the in vitro system . The activated product formed from biotin, ATP, and repressor preparation was identified as biotinyl 5'-adenylate by paper chromatography and hydroxamic acid formation . Synthetic biotinyl 5'-adenylate was as effective as biotin in the in vitro system (K0.5, 10 nM) and much more effective than biotin in the DNA-binding assay (K0.5 1.1 nM versus 1 microM) . These studies indicate that biotinyl 5'-adenylate has a more direct role in the regulation of the biotin genes than does biotin per se.

Proc Natl Acad Sci U S A, 1979 Nov, 76(11), 5572 - 6
Replication at restrictive temperatures in Escherichia coli containing a polCts mutation; Niwa O et al.; Escherichia coli cells with a polCts mutation contain a temperature-sensitive DNA polymerase II and fall to replicate DNA at the restrictive temperature (43 degreees C) . Mutants deficient in polymerizing activity of the other two recognized DNA polymerases in E . coli can replicate DNA . We have isolated temperature-resistant revertants from a strain containing polA-, polB-, and polCts mutations . These revertants grow at 43 degrees C, but analysis of partially purified DNA polymerase III from several such revertants shows a temperature-sensitive DNA polymerase III activity . Genetic analysis by P1 transduction confirms that such revertants can contain a polCts mutation and also a polA- mutation . We find that such revertants behave phenotypically as PolI+ cells (DNA polymerase I-containing), and extracts of such cells show a DNA polymerase I-like activity . Revertants of polA-, dnaAts and polA-, dnaBts strains do not show such a DNA polymerase activity.

Proc Natl Acad Sci U S A, 1979 Nov, 76(11), 5544 - 8
Attractants and repellents control demethylation of methylated chemotaxis proteins in Escherichia coli; Toews ML et al.; A group of methylated proteins, the methyl-accepting chemotaxis proteins (MCP), has been shown to play a central role in bacterial chemotaxis . Both methylation and demethylation of MCP occur continuously in the absence of added stimuli; these two processes are in balance such that a basal level of methylation is maintained . Attractants cause the methylation level to increase to a new value, whereas repellents bring about a decrease in level . Therefore, attractants and repellents must somehow perturb the balance between methylation and demethylation of MCP . In this report the effect of attractants on demethylation of MCP was monitored in two ways: (i) by following the disappearance of {methyl-3H}MCP and (ii) by measuring formation of {3H}methanol, the product of MCP demethylation . Both methods showed that addition of attractants causes a transient inhibition of MCP demethylation . Repellent addition has previously been shown to stimulate MCP demethylation . It is therefore concluded that control of demethylation plays a crucial role in changing the level of methylation of MCP in response to attractants and repellents.

Proc Natl Acad Sci U S A, 1979 Nov, 76(11), 5529 - 33
Control of phosphoenolpyruvate-dependent phosphotransferase-mediated sugar transport in Escherichia coli by energization of the cell membrane; Reider E et al.; The phosphoenolpyruvate-dependent phosphotransferase-mediated sugar transport in Escherichia coli is inhibited by the energized of the membrane . This was shown in intact cells as well as in membrane vesicles . Relaxation of the proton gradient by uncouplers stimulated the uptake of sugars via the phosphotransferase system in aerobically cultured cells . No such effect was seen in anaerobic cells, apparently because the cell membrane of these cells is poorly energized . Energization by respiration of D-lactate or ascorbate inhibited the phosphotransferase uptake system in membrane vesicles . This inhibition was reversed by the addition of cyanide . Oxamate, a specific inhibitor of lactate dehydrogenase, prevented the inhibitory effect of D-lactate . Membrane vesicles prepared from a cytochrome-less mutant were not energized by D-lactate oxidation and the phosphotransferase uptake system was not inhibited.

Proc Natl Acad Sci U S A, 1979 Nov, 76(11), 5480 - 4
Initiation of Escherichia coli ribosomal RNA synthesis in vivo; Lund E et al.; The 5'-terminal sequences of Escherichia coli ribosomal RNA precursors (pre-rRNAs) synthesized in vivo were characterized by RNA oligonucleotide sequence analysis . The 60- to 170-nucleotide-long 5'-end-specific fragments were produced by RNase III treatment of 30S and 18S pre-rRNAs . Comparison of the RNA oligonucleotides of these fragments with known DNA sequences of the promoter regions of several ribosomal RNA operons allows us to determine the start points of transcription of each operon . We conclude that transcription of most (and perhaps all) rRNA operons is initiated in vivo at two tandem promoters, called P1 and P2, which have recently been identified by in vitro transcription studies of several groups . Depending on the transcription unit, the initiating nucleotide at P1 promoters is either ATP or GTP, whereas at P2 promoters it is either CTP or GTP.

Mol Gen Genet, 1979 Nov, 176(3), 335 - 42
Stable yeast transformation with chimeric plasmids using a 2 micron-circular DNA-less strain as a recipient; Blanc H et al.; By using two chimeric plasmids containing yeast URA3 gene as a selection marker and 2 micron yeast DNA linked to the bacterial plasmid pCR1, a yeast strain devoid of any 2 micron DNA sequence was transformed . Recovery in E . coli of plasmids from yeast transformants showed that the 2 micron-less strain was able to maintain the chimeric plasmids as autonomous replicons, with very infrequent plasmid recombination . Hybridization experiments gave no evidence for integration of the URA3 DNA sequence in the chromosomal DNA . The transformed clones showed a high stability of the ura+ character during vegetative multiplication, even in the absence of selective pressure . The specific activity of orotidine 5' monophosphate decarboxylase (coded by the URA3 gene) was 5 to 10 fold higher than in the wild type . These features should offer new possibilities for cloning with yeast.

Mol Gen Genet, 1979 Nov, 176(3), 313 - 8
The gene for ribosomal protein L25 (rplY) maps at 47.3 min near nalA in Escherichia coli K-12; Schnier J et al.; A temperature sensitive mutant, termed JE1306, derived from Escherichia coli strain PA3092 was found to have an alteration in the ribosomal protein L25 . Crosses with various Hfr strains and transductions with P1 kc phage have revealed that the mutation maps at 47.3 min between nalA and fpk, in a region where no ribosomal protein gene has so far been located . The gene affected by this mutation is most probably the structural gene for protein L25 (rplY), because a strain heteromerozygous for the region shows both wild type and mutant forms of protein L25.

Immunology, 1979 Nov, 38(3), 503 - 8
The binding of LPS to the lymphocyte surface; Symons DB et al.; Bacterial lipopolysaccharide (LPS) from Escherichia coli labelled with tritium has been used to follow the binding of LPS to lymphocytes . Binding to cells rose to a maximum 2-7 min after addition of {3H}-LPS, followed by loss of {3H}-LPS from cells, reducing to about 10% of the peak level at 20-30 min . Peripheral blood lymphocytes, mesenteric lymph node and thymus cells of the pig and CBA, C3H/He and C3H/HeJ mouse spleen cells all bound {3H}-LPS transiently at similar levels . It is concluded that this type of LPS binding cannot be solely responsible for the preferential stimulation of B cells by LPS.

Eur J Biochem, 1979 Nov, 101(2), 469 - 73
Interaction of arginine with the ribosomal peptidyl transferase centre; Palacian E et al.; Arginine inhibits the formation of acetylleucyl-puromycin from C(U)-A-C-C-A-LeuAc and puromycin ('fragment reaction'), catalized by Escherichia coli and yeast ribosomes . From 18 different L-amino acids assayed, arginine was the most effective in producing inhibition (50% inhibition at 20 mM, with 1 mM puromycin) . L-Argininamide and D-arginine gave about the same inhibition as L-arginine . The inhibition by L-arginine is competitive with respect to puromycin . The plot of the slopes obtained in a Lineweaver and Burk representation versus {Arg}2, and the plot of 1/v versus {Arg}2 at a fixed concentration of puromycin, are linear, which seems to indicate that two arginine molecules must interact at the puromycin binding site to produce inhibition . In addition to the 'fragment reaction', arginine inhibits the non-enzymatic binding of AcPhe-tRNA, C(U)-A-C-C-A-Leu and C(U)-A-C-C-A-LeuAc to ribosomes . However, it does not inhibit poly(U)-directed polyphenylalanine synthesis or the reaction of puromycin with AcPhe-tRNA previously bound to the peptidyl site . The results agree with arginine binding to the acceptor site, and with a sequential mechanism for the 'fragment reaction', puromycin binding first.

J Med Microbiol, 1979 Nov, 12(4), 487 - 96
The ability of cholestyramine resin and other adsorbents to bind Escherichia coli enterotoxins; Mullan NA et al.; Several adsorbent materials were evaluated for their ability to bind Escherichia coli enterotoxins . Cholestyramine, a strong anion-exchange resin, bound the heat-labile and the heat-stable types of enterotoxin and reduced significantly their effects in some animal models . However, its efficacy in the treatment of diarrhoeic piglets appeared to be adversely affected by the presence of milk in the alimentary tract.

Genetika, 1979 Nov, 15(11), 1971 - 8
{Nature of the compatible inheritance of hybrid plasmid pAS8 and its deletion mutants with replicon ColE1}; Stepanov AI et al.; Hybrid plasmid pAS8, that consists of RP4 and ColE1 replicons, is incompatible with RP4 but co-exists with ColE1 replicon . The deletion mutants of pAS8, that replicates under the control of ColE1 replicon only, are incompatible with ColE1 derivatives, although the copy number of pAS8 and its deletion mutants in the cell is the same (1-3 per the chromosome) . Incompatibility effect of plasmids is expressed in a sharp decrease in transformant's yield during selection of incoming and resident plasmids markers . In this case incompatibility is a very fast process, that leads to the elimination of resident or incoming plasmid just before plating on the selective medium . On the base of negative control theory, the repressors yield, synthesized in the presence of 1-3 copies of the deletion mutant is enough for the expression of ColE1-specific incompatibility . This ColE1 incompatibility is probably connected with the functional activity of ColE1 replicon . When ColE1 factor replicates under the control of RP4 replicon the expression of ColE1-specific incompatibility does not occur . Possibly, the incompatibility effect takes place when pAS8 deletion mutants cause the synthesis of ColE1-specific repressor . Also, the replicons of ColE1 may competein the membrane attachment site.

Genetika, 1979 Nov, 15(11), 1918 - 24
{Chloroplast DNA cloning in Escherichia coli . II . The properties of the recombinant plasmids bearing the EcoRI fragments of pea chloroplast DNA and the cloning of the DNA sequences with rRNA genes}; Andrianov VM et al.; Previously a method of selection of colicine-defective recombinant plasmids by mitomycin C was described . A series of recombinant plasmids (CPS) with various EcoRI-fragments of pea chloroplast DNA has been obtained . This paper describes some properties of cloned fragments replicated in Escherichia coli . The alkali stability of recombinant plasmid DNAs has been demonstrated, indicating the absence of ribonucleotides in their structure . Heterogeneity of chloroplast DNA in nucleotide composition was demonstrated using ultracentrifugation analysis of CPS-plasmid DNAs in CsCl-actinomycin D density gradient . Pea chloroplast rDNA was cloned in recombinant plasmids.

Eur J Biochem, 1979 Nov 1, 101(1), 123 - 33
Translation by Escherichia coli ribosomes of alfalfa mosaic virus RNA 4 can be initiated at two sites on the monocistronic message; Castel A et al.; Substantial evidence is provided to corroborate our previous finding that Escherichia coli ribosomes recognize two binding sites on the 5' end of alfalfa mosaic virus (AMV) RNA 4 {for a preliminary report see Castel, A., Kraal, B., Kerklaan, P . R . M., Klok, J., and Bosch, L . (1977) Proc . Natl Acad . Sci . U.S.A . 74, 5509--5513} . Translation can start at either site using AcPhe-tRNA or fMet-RNA as initiator and takes place in the same reading frame along the monocistronic mRNA . The size and composition of the isolated extra NH2-terminal fragment of the acetylphenylalanyl product were found to be in agreement with the 5' non-coding region of the messenger . Removal of the 5'-terminal cap structure of AMV RNA 4 did not influence significantly both initiation reactions . Ribosomal protein S1 was essential for binding as well as incorporation of both fMet-tRNA and AcPhe-tRNA . A similar interaction on the ribosome was found for AcPhe-tRNA directed by AMV RNA 4 as for fMet-tRNA directed by either AMV RNA 4 or MS2 RNA with respect to the influence of initiation factors . It is concluded that the heterologous plant viral messenger is reliably translated in the E . coli system and that E . coli ribosomes recognize with high specificity an extra initiation site close to the 5' extremity of the messenger . The relationship of this site to a hypothetical entry site involved in the early recognition in the initiation mechanism between ribosome and messenger is discussed.

J Neurosurg, 1979 Nov, 51(5), 685 - 90
Production of experimental brain abscess in the rat; Winn HR et al.; Experimental evaluation of brain abscess has been inhibited by the lack of a simple and reproducible model in small animals . A stereotaxic headholder and slow infusion of 1 microliter of saline, containing a known number of bacteria, were used to produce brain abscess consistently in the rat . The natural history of the brain abscess produced by this technique closely simulated that found in the human clinical situation.

J Bacteriol, 1979 Nov, 140(2), 620 - 33
Regulated breakdown of Escherichia coli deoxyribonucleic acid during intraperiplasmic growth of Bdellovibrio bacteriovorus 109J; Rosson RA et al.; During growth of Bdellovibrio bacteriovorus on {2-14C}deoxythymidine-labeled Escherichia coli, approximately 30% of the radioactivity was released to the culture fluid as nucleoside monophosphates and free bases; the remainder was incorporated by the bdellovibrio . By 60 min after bdellovibrio attack, when only 10% of the E . coli deoxyribonucleic acid (DNA) had been solubilized, the substrate cell DNA was degraded to 5 X 10(5)-dalton fragments retained within the bdelloplast . Kinetic studies showed these fragments were formed as the result of sequential accumulation of single- and then double-strand cuts . DNA fragments between 2 X 10(3) and 5 X 10(5) daltons were never observed . Chloramphenicol, added at various times after initiation of bdellovibrio intraperiplasmic growth on normal or on heated E . coli, which have inactivated deoxyribonucleases, inhibited further breakdown and solubilization of substrate cell DNA . Analysis of these intraperiplasmic culture deoxyribonuclease activities showed that bdellovibrio deoxyribonucleases are synthesized while E . coli nucleases are inactivated . It is concluded that continuous and sequential synthesis of bdellovibrio deoxyribonucleases of apparently differing specificities is necessary for complete breakdown and solubilization of substrate cell DNA, and that substrate cell deoxyribonucleases are not involved in any significant way in the degradation process.

J Bacteriol, 1979 Nov, 140(2), 518 - 24
Alterations of deoxyribonucleoside triphosphate pools in Escherichia coli: effects on deoxyribonucleic acid replication and evidence for compartmentation; Pato ML; Inhibition of ribonucleic acid synthesis in Escherichia coli 15 TAU bar with rifampin or streptolydigin leads to large increases in the sizes of cellular ribonucleoside and deoxyribonucleoside triphosphate pools . Inhibition of protein synthesis leads to increases in the sizes of all nucleoside triphosphate pools except the guanosine triphosphate and deoxyguanosine triphosphate pools; a decrease in the size of the latter pool may be responsible for the slowing of deoxyribonucleic acid replication fork movement observed in this strain in the absence of protein synthesis . Analysis of the kinetics of incorporation of labeled precursors into deoxyribonucleic acid and into cellular pools suggests that functional compartmentation of nucleotide pools exists, allowing the incorporation of exogenously supplied precursors into deoxyribonucleic acid without prior equilibration with the cellular pools.

J Bacteriol, 1979 Nov, 140(2), 445 - 51
Effect of blocking protein synthesis at nonpermissive temperatures on temperature-sensitive deoxyribonucleic acid mutants of Escherichia coli; Evans IM et al.; When protein synthesis was blocked in temperature-sensitive deoxyribonucleic acid synthesis mutants of Escherichia coli at nonpermissive temperatures, it reduced the amount of apparent subsequent chain elongation to approximately half that observed in the mutants either at nonpermissive temperatures alone or when protein synthesis was blocked at the permissive temperature . Blocking protein synthesis at the nonpermissive temperatures for periods of 40 min caused the loss of ability to reinitiate deoxyribonucleic acid synthesis at the permissive temperature.

J Bacteriol, 1979 Nov, 140(2), 436 - 44
Multiple, independent components of ultraviolet radiation mutagenesis in Escherichia coli K-12 uvrB5; Smith KC et al.; Reversion systems involving the lacZ53(amber) and leuB19)missense) mutations were developed to study the mutant frequency response of Escherichia coli K-12 uvrB5 (SR250) to ultraviolet radiation (254 nm) . A one-hit mutant frequency response was discernible at ultraviolet radiation fluences below approximately 0.5 J m-2 . At higher fluences the overall mutant frequency response could be resolved into one-hit and two-hit components . A new interpretation of the published data on E . coli K-12 indicates that SR250 is not unique in this respect . In addition, the Lac reversion system showed enhanced mutagenesis after ultraviolet radiation fluences of approximately 1 to 3 J m-2, whereas the Leu reversion system did not . We conclude that the complex ultraviolet radiation mutant frequency response curves for E . coli K-12 uvrB5 were the result of three independent mutagenic processes for Lac reversion and two for Leu reversion.

J Bacteriol, 1979 Nov, 140(2), 388 - 94
Role of the ftsA gene product in control of Escherichia coli cell division; Donachie WD et al.; The kinetics of cell division have been studied in a strain of Escherichia coli which has an amber mutation in the ftsA gene and which also carries a temperature sensitive amber suppressor . This strain is therefore temperature sensitive for the synthesis of the ftsA protein . Cells of this strain were able to divide only if the synthesis of this protein took place during a specific part of the cell cycle . This was a short period (roughly 10 min in duration) immediately before the normal time of cell division.

J Bacteriol, 1979 Nov, 140(2), 377 - 80
Microcalorimetric study of Escherichia coli aerobic growth: kinetics and experimental enthalpy associated with growth on succinic acid; Dermoun Z et al.; A new batch calorimeter was used to study the aerobic growth of Escherichia coli in a minimal containing a growth-limiting concentration of succinic acid . The shape of the thermograms obtained was simple when the energy source was the only growth-limiting factor and showed a stationary phase when the oxygen transfer was limiting . The experimentally determined value of the heat production during growth was found to be significantly lower than the heat of combustion of the succinic acid corrected for the assimilated-substrate fraction . An interpretation has been given to explain the difference between the experimental and the theoretical values.

J Bacteriol, 1979 Nov, 140(2), 311 - 9
Inversion in the lactose region of Escherichia coli K-12; Savic DJ; A spontaneous mutant of Escherichia coli K-12, strain SY99, with an inversion in the lactose region was isolated and partially characterized . The inversion was detected due to inverse chromosomal conjugational transfer after introduction of an F42 (F'lac) episome . The termini of the inversion are between proAB and lac on one side and lac and proC on the other . The inverse conjugational transfer in SY99 did not appear to be absolute but was always accompanied by a residual "normal" counterclockwise mobilization . This residual transfer was further shown to be caused by the intrinsic instability of this region (at least in the line W3110) . The possible involvement of IS3 elements flanking the lactose operon is discussed.

CRC Crit Rev Biochem, 1979 Nov, 7(1), 45 - 74
Analysis of in vitro replication of different DNAs; Hurwitz J; The conversion of single-stranded circular DNA to duplex DNA in vitro occurs by at least three different mechanisms . These differences reside in the manner of priming of these DNAs . In contrast, the elongation of primed DNA templates is a general reaction . A number of these proteins have been isolated and further characterized . In addition, cell-free preparations capable of supporting phi X RFI DNA replication as well as the synthesis of progeny viral phi X174 single-stranded circular DNA have been prepared.

Cancer Res, 1979 Nov, 39(11), 4512 - 5
Correlation between metabolic reduction rates and electron affinity of nitroheterocycles; Olive PL; Nitroheterocyclic compounds can selectively sensitize hypoxic (tumor) cells to radiation damage in vitro . However, results in vivo have generally been less optimistic, inasmuch as metabolic reduction of these drugs not only limits effective lifetime but also produces metabolic intermediates with marked cytotoxic and carcinogenic activity . With three reducing systems in vitro, E . coli B/r, mouse L-929 cells, and mouse liver microsomes, the rate of nitroreduction of several nitroheterocycles was found to be proportional to their electron affinity (half-wave reduction potential) . Relative to the rate of nitrofurazone reduction in each system, metronidazole (Flagyl), N-hydroxyethyl-3,5-dinitropyrrole, misonidazole, nifuroxime, nitrofurantoin, and furylfuramide were metabolized about 200, 20, 2, 1.4, and 1.2 times less rapidly, while 3,5-dinitrobenzonitrile, 2,5-dinitrophenol, and 5-nitro-2-furaldehyde diacetate were reduced 2, 3, and 4 times more rapidly . Since nitroreduction has previously been correlated with subsequent cytotoxicity, DNA damage, and mutagenicity, the present results suggest that improvements in the therapeutic efficacy of nitroheterocycles (i.e., sensitization without toxicity and carcinogenicity) will be dependent on development of drugs with more appropriate pharmacological properties.

Br J Haematol, 1979 Nov, 43(3), 457 - 63
Reduced leucocyte alkaline phosphatase activity and decreased NBT reduction test in induced iron deficiency anaemia in rabbits; Celada A et al.; Iron deficiency anaemia was induced in rabbits by repeated bleeding . The leucocyte alkaline phosphatase (LAP) of 26 +/- 28 units was significantly reduced compared with control values of 233 +/- 35 units (P less than 0.001) . Leucocyte NBT reduction was also diminished, both in Hanks solution (P less than 0.01) and in autologous serum (P less than 0.001) . After administration of iron, these values returned to normal . The results suggest that reduced LAP may reflect a deficiency of iron dependent constituents which are necessary for the integrity of normal granulocyte metabolism.

Mol Biol (Mosk), 1979 Nov-Dec, 13(6), 1341 - 9
{Effect of DNA supercoiling on transcription performed by normal and mutant Escherichia coli RNA-polymerases}; Mirkin SM et al.; A specific DNA-gyrase, inhibitor, coumermycin A1, causes differential changes in the spectrum of proteins synthesized in E . coli wild types cells, while protein spectrum in the mutant cells with coumermycin-resistant DNA-gyrase is left unaffected . The mutation of RNA-polymerase RpoB265 lowers the sensitivity of bacteria to coumermycin A1, whereas the RpoC3 enhances it . The differences between the normal and mutant RpoB265 RNA polymerases on interaction in vitro with ColE1 DNA plasmid depend on its supercoiling . No dependences of this kind were detected when comparing the normal and RpoC3-RNA polymerase . The obtained data indicate that the template supercoiling may significantly affect the transcription in vivo and that the properties of RNA polymerase may in some cases define this influence.

Can J Biochem, 1979 Nov, 57(11), 1281 - 3
In vivo preparation of {32P}cAMP and thin-layer chromatography of cAMP-related compounds; Yamazaki H et al.; A simple and rapid method for preparing {32P}adenosine 3'5'-cyclic monophosphate (cAMP) is described . A culture of an Escherichia coli mutant which excretes cAMP about 150 times faster than does a wild-type strain was incubated overnight with {32P}orthophosphate of high specific activity (e.g., 4000 Ci/mol (1 Ci = 37 GBq) . The {32P}cAMP which accumulated extracellularly was then purified to 99.9% radiochemical purity in less than 4 h by adsorption to charcoal and alumina column chromatography . A two-dimensional chromatography system using a PEI-cellulose plate is also described which should prove useful for studying cAMP metabolism with 32P- or 3H-labeled cAMP or ATP.

Proc Natl Acad Sci U S A, 1979 Nov, 76(11), 5596 - 600
Synthesis of simian virus 40 t antigen in Escherichia coli; Roberts TM et al.; Plasmids are constructed by using recombination in vitro according to Roberts, T.M., Kacich, R . & Ptashne, M . (1979) Proc . Natl . Acad . Sci . USA 76, 760-764 in which the t antigen gene of simian virus 40 is fused to a promoter of the Escherichia coli lac operon . In the fusions, transcription commences at the lac promoter, and, in some of the fusions, translation begins at the ATG initiator codon of the t gene . This translation is directed most efficiently by those plasmids in which the lac sequences abut the t gene such that a hybrid ribosome binding is encoded . In this case, the Shine-Dalgarno sequence is of lac origin but the ATG derives from the t gene . translation from this initiator codon is greatly decreased if the lac sequences are separated from the ATG by 17 base pairs and is abolished if the AT of this triplet is deleted . Cells bearing the productive fusions synthesize a 20,000-dalton protein with t antigenic determinants . This protein has an isoelectric point(s) indistinguishable from that of t antigen isolated from simian virus 40-transformed cells . Moreover, a partial sequence of the amino-terminal region of the bacterial product is that predicted for authentic t antigen . We conclude that these bacteria are for authentic t antigen . We conclude that these bacteria are producing a protein, the sequence of which is identical to that of authentic t antigen unfused to other polypeptides.

Proc Natl Acad Sci U S A, 1979 Nov, 76(11), 5567 - 71
Spliced adenovirus-associated virus RNA; Laughlin CA et al.; We describe the structure of cytoplasmic RNA species transcribed from the DNA of adenovirus-associated virus, a defective parvovirus . The RNA was hybridized with minus strand template DNA and visualized in the electron microscope . Alternatively, the DNA.RNA duplex molecules were digested with nuclease S1 or Escherichia coli exonuclease VII and analyzed by agarose gel electrophoresis . A set of RNA species was observed with 5' terminal at map positions 5, 13, 19, or 39 and a 3' terminus and poly(A) tail at position 96 (one map unit is equivalent to 1% of genome length) . Most of these RNAs are spliced and lack sequences approximately between positions 40 and 49 . Some RNA preparations also contained unspliced molecules with 5' and 3' terminal at positions similar to those in the spliced RNA.

Proc Natl Acad Sci U S A, 1979 Nov, 76(11), 5520 - 3
Regulation of synthesis of a major outer membrane protein: cyclic AMP represses Escherichia coli protein III synthesis; Mallick U et al.; Cyclic AMP is the effector molecule for both positive and negative control of synthesis of several Escherichia coli proteins . Among the latter is the major outer membrane protein III . The control mechanism occurs at the level of transcription and involves the cyclic AMP receptor protein . The repressing system is saturated at lower concentrations of cyclic AMP than is the positive control system.

Mol Gen Genet, 1979 Nov, 176(3), 449 - 50
Control of minicell producing cell division by cAMP-receptor protein complex in Escherichia coli; Kumar S et al.; It has been established that the strain CA8000 of Escherichia coli K12 produces minicells . This phenotype of CA8000 has been shown to be suppressed by additional mutations in cya or crp genes . Minicell production by cya+ crp+ min bacteria is probably a consequence of error, introduced by horizontal growth, in the selection of site on the envelope for initiation of hemispherical growth.

Mol Gen Genet, 1979 Nov, 176(3), 375 - 7
The stimulation of Escherichia coli stringent factor-dependent synthesis of guanosine 3',5'-polyphosphate {(p)ppGpp} by rat liver ribosomal proteins; Fehr S et al.; The effect of groups of proteins from rat liver ribosomes on the Escherichia coli stringent factor-catalyzed synthesis of (p)ppGpp was tested . Most groups were capable of supporting (p)ppGpp synthesis; the exceptions were A40, B140, B240 and B160 which contain proteins which are relatively less basic than those in the active groups . The capacity of 30 individual rat liver ribosomal proteins to activate stringent factor was assessed; most sustained the synthesis of (p)ppGpp . Proteins S12, S21, L12, P1, and P2 (which are acidic or relatively acid) had no activity; proteins S6, S8, and L3 were the most active: the others had moderate activity.

Mol Gen Genet, 1979 Nov, 176(3), 343 - 50
Involvement of cyclic AMP and its receptor protein in the sensitivity of Escherichia coli K 12 toward serine: excretion of 2-ketobutyrate, a precursor of isoleucine; Daniel J et al.; A relationship between serine-induced growth sensitivity and the cAMP-CAP complex is established . Mutants of Escherichia coli K 12 deficient either in the cya or crp gene function exhibit a resistant phenotype on serine media although they harbor a relA allele normally leading to sensitivity toward serine . The presence of a crp allele in a cya delta relA background restores the sensitivity phenotype, while the analysis of serine resistant mutants selected from a crp cya delta relA strain shows that the mutation leading to resistance is located at, or very near, the crp gene, giving a more or less Crp- phenotype . In addition crp cya delta relA strains excrete large quantities of 2-ketobutyrate when grown on glucose M63 medium . This excretion is unambiguously linked to the presence of the crp allele and is correlated with an enhanced threonine deaminase activity . Besides, the complex regulation exerted on the acetolactate synthase activities is discussed.

Gene, 1979 Nov, 7(3-4), 335 - 42
Construction and characterization of a recombinant plasmid encoding the gene for the thymidine kinase of Herpes simplex type 1 virus; Enquist LW et al.; We have constructed a hybrid plasmid by insertion of the thymidine kinase (TK) gene of Herpes simplex virus (HSV) type I at the BamHI site on Escherichia coli plasmid pBR322 . The restriction endonuclease cleavage site map for the viral DNA fragment was determined for ten nucleases, and the insert in the recombinant plasmid has the same restriction nuclease digestion pattern as bona fide viral DNA . This result indicates that the plasmid contains an accurate copy of the viral DNA . The viral TK gene carried on the plasmid can be introduced into mammalian cells where it is expressed . This source of DNA with a selectable marker should be of considerable practical use in gene-transfer experiments in mammalian cells.

J Bacteriol, 1979 Nov, 140(2), 459 - 67
Transport of cyclic adenosine 3',5'-monophosphate across Escherichia coli vesicle membranes; Goldenbaum PE et al.; The uptake and efflux of cyclic adenosine 3',5'-monophosphate (3',5'-cAMP) by Escherichia coli membrane vesicles were studied . Metabolic energy was not required for the uptake process and was found to actually decrease the amount of 3',5'-cAMP found in the vesicles . 3',5'-cAMP uptake exhibits saturation kinetics (Km = 10 mM, Vmax = 2.8 nmol/mg of protein per min) and was competitively inhibited by a number of 3',5'-cAMP analogs . The uptake of 3',5'-cAMP was found to be sharply affected by a membrane phase transition . The excretion of 3',5'-cAMP was studied by using everted membrane vesicles . Efflux in this system was dependent upon metabolic energy and was reduced or abolished by uncouplers . Different energy sources powered efflux at different rates, showing a relationship between the degree of membrane energization and rate of excretion of 3',5'-cAMP . The efflux process also displayed saturation kinetics (Km = 10.0 mM, Vmax = 0.98 nmol/mg of protein per min) and was competitively inhibited by the same 3',5'-cAMP analogs and to the same degree as was the uptake process . 3',5'-cAMP was found to be chemically unaltered by both the uptake and excretion processes . These data are interpreted as showing that the uptake and excretion of 3',5'-cAMP in E . coli membrane vesicles are carrier-mediated phenomena, possibly employing the same carrier system . Uptake is by facilitated diffusion whereas efflux is via an energy-dependent, active transport process . Evidence is presented showing that cells can regulate the number of 3',5'-cAMP transport carriers . The rate of 3',5'-cAMP excretion is possibly regulated by both the degree of membrane energization and the number of carriers present per cells.

J Bacteriol, 1979 Nov, 140(2), 415 - 23
Production and excretion of cloacin DF13 by Escherichia coli harboring plasmid CloDF13; Van Tiel-Menkvled GJ et al.; The production and the mechanism of excretion of cloacin DF13 were investigated in noninduced and mitomycin C-induced cell cultures . A mitomycin C concentration was selected which did not cause lysis of cloacinogenic cells, but at the same time induced a maximal production of cloacin DF13 . Native cloacin DF13, possessing killing activity, was first released into the cytoplasm . Shortly thereafter, the bacteriocin was transported through the cytoplasmic membrane and accumulated in the periplasm . Finally, cloacin DF13 was excreted into the culture medium . A small amount of cloacin DF13 remained associated with the cell surface . Producing cells did not become permeable for the cytoplasmic enzyme beta-galactosidase . Apparently the cloacin DF13 leaves the producing cells by an excretion process which is not similar to the mechanism proposed for bacterial secretory proteins . The processes of excretion by producing cells and of uptake by susceptible cells were also not identical because mutant cloacin DF13, which was not transported through the outer membrane into susceptible cells, was excreted like the wild-type cloacin DF13 . The composition of the culture medium greatly affected production of cloacin DF13 . The presence of sugars known to cause catabolite repression not only inhibited the production but also strongly reduced the excretion of cloacin DF13 into the culture medium.

Proc Natl Acad Sci U S A, 1979 Nov, 76(11), 5799 - 803
Gene expression of an Escherichia coli ribosomal RNA promoter fused to structural genes of the galactose operon; Ota Y et al.; The promoter region of the rrnB ribosomal RNA gene of Escherichia coli has been ligated within the epimerase gene (galE) of the galactose operon in a lambda phage vector . The recombinant lambda phage has been characterized by restriction mapping and assays of both galK (galactokinase) gene activity and galactose messenger RNA hybridization . In such lyosgens, expression of the fused galactose operon occurs as a function of growth rate in a manner characteristic of ribosomal RNA gene expression and is subject to stringent control by amino acid availability for protein synthesis . Galactose messenger RNA arising from the ribosomal promoter is not as metabolically stable as ribosomal RNA.

Mol Gen Genet, 1979 Nov, 176(3), 361 - 8
Cloning the trpR gene; Roeder W et al.; In Escherichia coli, the structural gene for purine nucleoside phosphorylase, deoD, is subject to insertional inactivation by prophage lambda . From one such secondary site lambda lysogen, strain SP265, one may isolate deletions that remove all or part of the trpR gene and other genes in the deo-thr sector of the E . coli chromosome . Specialized transducing phages harboring serB+ and trpR+ were liberated following induction of SP265 . All such phages were N-defective, bio-type pseudolysogens whose DNA persisted in the form of plasmids . A collection of transducing phages, differing in their complement of bacterial DNA, was used to locate cleavage sites for BamHI, SalI, and PvuI within the deoD-trpR region of the E . coli genome . The trpR gene lies within a specific 950 base pair BamHI-PvuI segment . A 1250 base pair BamHI fragment carrying a functional trpR gene was cloned into the amplifiable plasmid pBR322 . A single SalI site in this fragment was shown to lie within the TrpR gene . In two situations where increased gene dosage might generate elevated amounts of Trp repressor (N-defective trpR+ pseudolysogens and strains harboring pBR322 trpR+ plasmids) neither tryptophan auxotrophy, enhanced sensitivity to DL-5-methyl-tryptophan, nor super repression of the tryptophan biosynthetic enzymes was observed.

Gene, 1979 Nov, 7(3-4), 181 - 95
A rightward promoter to the left of the att site of lambda phage DNA: possible participant in site-specific recombination; Kravchenko VV et al.; The binding has been studied of Escherichia coli RNA-polymerase to the fragments of lambda DNA obtained by digestion with restriction endonucleases BsuI, HindIII, BamHI, EcoRI and HindII + III . There are at least six sites of RNA-polymerase binding in the b2-region . In vitro transcription of those BsuI-fragments of the b2-region which contain six binding sites is rightward . Therefore, the fragments contain promoters rather than mere RNA-polymerase binding sites . One of the promoters of the b2 region named patt was calculated to be about 50 bp to the left of the att site . We postulate that this promoter might correspond to the hef-target which was described as important for the site-specific recombination.

J Bacteriol, 1979 Nov, 140(2), 381 - 7
Suppression of tif-mediated induction of SOS functions in Escherichia coli by an altered dnaB protein; D'Ari R et al.; The tif-1 mutation in the Escherichia coli recA gene is known to cause induction of the various "SOS" functions at high temperature, including massive synthesis of the recA protein, lethal filamentation, elevated mutagenesis, and, in lambda lysogens, induction of prophage . It is shown here that the deoxyribonucleic acid initiation mutation dnaB252 suppresses all these manifestations of tif expression . Induction of lambda by ultraviolet irradiation, however, is not affected by the dnaB252 mutation . No similar suppression of tif is observed with other dnaB mutations affecting deoxyribonucleic acid elongation or with other deoxyribonucleic acid initiation mutations at the dnaA and dnaC loci . The fact that an alteration of the dnaB protein specifically suppresses tif-mediated SOS induction implies a role of the replication apparatus in this process, as has been suggested for ultraviolet induction . The induction of lambda is known to proceed via repressor cleavage, presumably promoted by an activated (protease) form of the recA protein . Since lambda induction is normal after ultraviolet irradiation of the tif-1 dnaB252(lambda) strain, tif-mediated induction in this strain may be blocked in a tif-specific step leading to activation of the recA (tif) protein . It is possible that the recA (tif) mutant protein may be directly involved in the replication complex in processes leading to this activation.

Proc Natl Acad Sci U S A, 1979 Nov, 76(11), 5524 - 8
Attenuation in the Escherichia coli tryptophan operon: role of RNA secondary structure involving the tryptophan codon region; Oxender DL et al.; The secondary structure of the terminated trp leader transcript from Escherichia coli was analyzed by RNase T1 partial digestion . Base-paired regions were recovered by nondenaturing gel electrophoresis and identified by denaturing gel electrophoresis and fingerprinting . The tandem tryptophan codons in the leader peptide coding region were found to be base paired with a more distal region of the transcript . This and other secondary structures that the trp leader RNA can form help explain the physiological response of the operon as well as the behavior of regulatory mutants.

J Biochem (Tokyo), 1979 Nov, 86(5), 1233 - 8
In vivo methylation of elongation factor Tu of Escherichia coli; Ohba M et al.; A protein existing mainly in the supernatant fraction of Escherichia coli was found to be methylated by accepting the methyl moiety originating from methionine . The protein was identified as peptide synthesis elongation factor Tu (EF-Tu) by the following criteria . 1) The methylatable protein separated at the same position as purified EF-Tu on two-dimensional gel electrophoresis . 2) The methylatable protein interacted with antiserum specific for EF-Tu . Amino acid analysis of the methyl-labeled protein suggested that the site of methylation was an epsilon-amino group of lysine.

Gene, 1979 Nov, 7(3-4), 197 - 215
Isolation and characterization of recombinant DNA plasmids carrying Drosophila tRNA genes; Dunn R et al.; Recombinant plasmids carrying Drosophila melanogaster tRNA genes were constructed by ligation of HindIII-cleaved Drosophila DNA to HindIII cut pBR322 DNA . 90 clones were isolated that contained genes for one or more of eleven tRNAs . 43 of the plasmids were characterized by a number of methods: restriction nuclease digestion; agarose gel electrophoresis; hybridization with individual, purified, 125I-labelled Drosophila tRNA molecules and in situ hybridization to Drosophila chromosomes . The results show that several different tRNA genes have been isolated which code for single, specific isoacceptors . The DNAs from 8 plasmids each hybridize to single sites on Drosophila polytene chromosomes . In addition, the data show examples of two different plasmids hybridizing to different loci coding for the same tRNA; this means that we have isolated representatives of tRNA genes which map at widely separated points on the Drosophila genome.

Genetika, 1979 Nov, 15(11), 1925 - 36
{Mutations in the purine nucleoside phosphorylase (pup) gene of Escherichia coli K-12 characterized by leaky damage to enzymatic activity and a pleiotropic effect}; Skladnev DA et al.; The phenotype of earlier obtained mutants AIR38 and AIR6 is caused by leaky mutations of the structural gene for purine nucleoside phosphorylase (pup) . These mutants are unable to grow on the medium with inosine as the only carbon source in the presence of thymidine . In contrast to ordinary leaky mutations, AIR38 and AIR6 are dominant in heterozygotes . When the strain F' with mutations AIR38 or AIR6 on episomes was used for conjugational matings with F- recA (pup+), recombinants with unexpected phenotype were observed: about 20% of recombinants F' became pup+ and thus the convertion of AIR38 and AIR6 alleles to pup+ took place . AIR38 mutation, unlike AIR6, is mapped in the proximal region of the pup gene and is characterized by pleyotropic effect on deo-genes: the inosine-induction of purine nucleoside phosphorylase in AIR38 mutant is absent and the induction of thymidine phosphorylase by exogenous thymidine is decreased . A speculation was made that the mutation AIR38 altered the structure of purine nucleoside phosphorylase in the site responsible for its interaction with membrane.

J Bacteriol, 1979 Nov, 140(2), 342 - 50
Transcriptional regulation of Escherichia coli K-12 major outer membrane protein 1b; Hall MN et al.; Eleven independent insertion mutations were isolated that prevented expression of major outer membrane protein 1b . Seven of the mutations were Mucts insertions located at ombP . These ompB::Mucts strains fell into two phenotypic classes with regard to expression of proteins 1a and 1b . The remaining four mutants were comprised of one Tn5 and three Mucts insertions mapping at par . The Mucts insertions at par were used to construct fusions of the lac operon to the par promoter . Expression of beta-galactosidase in these fusion strains reflected known regulatory properties of protein 1b . When an ompB allele was introduced into the par-lac fusion strains, beta-galactosidase activity was reduced 14- to 31-fold . Transcriptional regulation of the par gene and the existence of two functions at ompB are discussed . The results suggest that par is the structural gene for protein 1b and that an ompB gene product is a diffusible, positive regulatory element controlling expression of par.

Mol Biol (Mosk), 1979 Nov-Dec, 13(6), 1413 - 9
{Inhibition of RNA synthesis in vitro by antibodies against mononucleotides}; Makarova OV et al.; Antibodies against purine nucleotides were obtained from rabbits immunized with conjugates of bovine serum albumine with AMP or GMP . The antibodies purified by affinity chromatography on nucleoside monophosphate-human serum albumine-Sepharose columns inhibited RNA synthesis on native T4 phage DNA by E . coli RNA polymerase . The inhibition of transcription was due mainly to inhibition of the initiation stage of RNA synthesis.

J Antibiot (Tokyo), 1979 Nov, 32(11), 1181 - 5
Response to bleomycin of Escherichia coli mutants deficient in DNA repair; Yamamoto K et al.; The effect of bleomycin on the colony forming ability of Escherichia coli K12 strains in exponential growth at 37 degrees C was not affected by introducing recA13, lexA1, polA1 and uvrA6 mutations . For cells starved for amino acids, wild type strains became ten-fold more resistant to bleomycin, but again introducing lexA1, polA1 and uvrA6 strains did not change the effect on colony forming ability; however, starved recA13 cells were now four-fold more sensitive . Strains with recA13, lexA1 and polA1 mutations were always more sensitive than wild type to gamma rays under the same conditions as used for the bleomycin treatment . It is suggested that bleomycin-induced lesions may be concentrated in that part of the bacterial genomes at the cell wall, near the replication forks.

Infect Immun, 1979 Nov, 26(2), 453 - 7
In vitro adherence of radioactively labeled Escherichia coli in normal and cystitis-prone females; Parsons CL et al.; Numerous investigators report data obtained using an in vitro quantitative assay for measuring bacterial adherence to epithelial cells . We found this assay to contain significant sources of error in the large variation in number of bacteria bound per cell and in the dependence on the investigator's visual counting of bacteria bound per cell . In the modified assay described here, we eliminated the need for visual counting of bacteria by incorporating the use of radioactively labeled Escherichia coli . This allowed quantitation of bacterial adherence to as many as 50,000 vaginal cells, whereas the visual counting system limits the determination to perhaps 50 cells . We feel that the use of radioactively labeled bacteria in place of the visual counting system increases the validity and sensitivity of this assay . Using the modified method, we found no statistically significant differences among values for adherence of E . coli type 04 to the vaginal cells of control and cystitis-prone women at either pH 6.4 or 4.0.

J Biochem (Tokyo), 1979 Nov, 86(5), 1251 - 7
Phosphoenolpyruvate carboxylase of Escherichia coli . Affinity labeling with bromopyruvate; Kameshita I et al.; Phosphoenolpyruvate carboxylase {EC 4.1.1.31} from Escherichia coli W was alkylated by incubation with bromopyruvate, substrate analog, leading to irreversible inactivation . The reaction followed pseudo-first-order kinetics . Mg2+, an essential cofactor for catalysis, enhanced the inactivation, and the enhancing effect increased as the pH increased . The inactivation rate showed a tendency to saturate with increasing concentrations of bromopyruvate, indicating that an enzyme-bromopyruvate complex was formed prior to the alkylation . DL-Phospholactate, a potent competitive inhibitor with respect to phosphoenolpyruvate, protected the enzyme from inactivation in a competitive manner . Examination of the acid hydrolysate of the enzyme modified with {14C}bromopyruvate by paper chromatography showed that radioactivity was solely incorporated into carboxyhydroxyethyl cysteine . In addition, determination of sulfhydryl groups of the native and modified enzymes with 5,5'-dithiobis(2-nitrobenzoate) showed that inactivation occurred concomitant with the modification of one cysteinyl residue per subunit . The results indicate that bromopyruvate reacted with the enzyme as an active-site-directed reagent.

J Biochem (Tokyo), 1979 Nov, 86(5), 1239 - 49
Studies on regulatory functions of malic enzymes . VII . Structural and functional characteristics of sulfhydryl groups in NADP-linked malic enzyme from Escherichia coli W; Iwakura M et al.; NADP-linked malic enzyme from Escherichia coli W contains 7 cysteinyl residues per enzyme subunit . The reactivity of sulfhydryl (SH) groups of the enzyme was examined using several SH reagents, including 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) and N-ethylmaleimide (NEM) . 1 . Two SH groups in the native enzyme subunit reacted with DTNB (or NEM) with different reaction rates, accompanied by a complete loss of the enzyme activity . The second-order modification rate constant of the "fast SH group" with DTNB coincided with the second-order inactivation rate constant of the enzyme by the reagent, suggesting that modification of the "fast SH group" is responsible for the inactivation . When the enzyme was denatured in 4 M guanidine HCl, all the SH groups reacted with the two reagents . 2 . Althoug the inactivation rate constant was increased by the addition of Mg2+, an essential cofactor in the enzyme reaction, the modification rate constant of the "fast SH group" was unaffected . The relationship between the number of SH groups modified with DTNB or NEM and the residual enzyme activity in the absence of Mg2+ was linear, whereas that in the presence of Mg2+ was concave-upwards . These results suggest that the Mg2+-dependent increase in the inactivation rate constant is not the result of an increase in the rate constant of the "fast FH group" modification . 3 . The absorption spectrum of the enzyme in the ultraviolet region was changed by addition of Mg2+ . The dissociation constant of the Mg2+-enzyme complex obtained from the Mg2+- dependent increment of the difference absorption coincided with that obtained from the Mg2+- dependent enhancement of NEM inactivation . 4 . Both the inactivation rate constant and the modification rate constant of the "fast SH group" were decreased by the addition of NADP+ . The protective effect of NADP+ was increased by the addition of Mg2+ . Based on the above results, the effects of Mg2+ on the SH-group modification are discussed from the viewpoint of conformational alteration of the enzyme.

Genetika, 1979 Nov, 15(11), 1963 - 70
{Effect of plasmid F'Col+trp+ on the transfer of plasmid RP4}; Gol'dfarb DM et al.; Interaction of conjugative plasmids F'colV colB trp and PR4 in Escherichia coli host was studied during the transfer of the plasmids from cell to cell . The plasmid F'colV colB trp is found to stimulate the transfer of RP4 from the diplasmid strain . This seems to be due to stabilization of the conjugating pairs which require normal pili coded by the plasmid F'colV colB trp.

J Bacteriol, 1979 Nov, 140(2), 395 - 9
Sucrose transport by the Escherichia coli lactose carrier; Heller KB et al.; Several lines of evidence suggest that sucrose is transported by the lactose carrier of Escherichia coli . Entry of sucrose was monitored by an osmotic method which involves exposure of cells to a hyperosmotic solution of disaccharide (250 mM) . Such cells shrink (optical density rises), and if the solute enters the cell, there is a return toward initial values (optical density falls) . By this technique sucrose was found to enter cells at a rate approximately one third that of lactose . In addition, the entry of {14C}sucrose was followed by direct analysis of cell contents after separation of cells from the medium by centrifugation . Sucrose accumulated within the cell to a concentration 160% of that in the external medium . The addition of sucrose to an anaerobic suspension of cells resulted in a small alkalinization of the external medium . These data are consistent with the view that the lactose carrier can accumulate sucrose by a proton cotransport system . The carrier exhibits a very low affinity for the disaccharide (150 mM) but a moderately rapid Vmax.

J Bacteriol, 1979 Nov, 140(2), 320 - 6
Rhamnose-induced propanediol oxidoreductase in Escherichia coli: purification, properties, and comparison with the fucose-induced enzyme; Boronat A et al.; Escherichia coli are capable of growing anaerobically on L-rhamnose as a sole source of carbon and energy and without any exogenous hydrogen acceptor . When grown under such condition, synthesis of a nicotinamide adenine dinucleotide-linked L-lactaldehydepropanediol oxidoreductase is induced . The functioning of this enzyme results in the regeneration of nicotinamide adenine dinucleotide . The enzyme was purified to electrophoretic homogeneity . It has a molecular weight of 76,000, with two subunits that are indistinguishable by electrophoretic mobility . The enzyme reduces L-lactaldehyde to L-1,2-propanediol with reduced nicotinamide adenine dinucleotide as a cofactor . The Km were 0.035 mM L-lactaldehyde and 1.25 mM L-1,2-propanediol, at pH 7.0 and 9.5, respectively . The enzyme acts only on the L-isomers . Strong substrate inhibition was observed with L-1,2-propanediol (above 25 mM) in the dehydrogenase reaction . The enzyme has a pH optimum of 6.5 for the reduction of L-lactaldehyde and of 9.5 for the dehydrogenation of L-1,2-propanediol . The enzyme is, according to the parameters presented in this report, indistinguishable from the propanediol oxidoreductase induced by anaerobic growth on fucose.

Nucleic Acids Res, 1979 Oct 25, 7(4), 971 - 80
A unique method utilizing antinucleotide antibodies for evaluating changes in the levels of modified nucleosides of tRNAs from crude extracts of whole cells; Vold BS et al.; The utilization of antibodies directed toward modified nucleosides in evaluating changes in the levels of certain modified nucleosides in transfer RNA is reported . Antibodies directed toward the N6-(delta 2-isopentenyl)adenosine modification were used in this model system with a mutant strain of Escherichia coli designated ipaA . The procedure is rapid, sensitive, and specific . In addition, it does not depend on the existence of an in vitro remodification system or any radiochemical labeling of the tRNA . By varying the extraction technique, the method could be applied to procaryotic or eukaryotic cell lines . The existence of antibodies specific for other nucleoside modifications makes this a system that is potentially applicable to a variety of deficiencies in the modification of both tRNA and rRNA.

Nucleic Acids Res, 1979 Oct 25, 7(4), 879 - 93
The influenza virus haemagglutinin gene: cloning and characterisation of a double-stranded DNA copy; Sleigh MJ et al.; A protocol has been developed for the synthesis of a double-stranded DNA (dsDNA) copy of the influenza virus RNA genome segment which codes for the major surface antigen, haemagglutinin (HA) . This dsDNA copy was inserted, after digestion with S1 nuclease and poly (dC) tailing with terminal transferase, into poly(dG)-tailed, PstI-cut, pBR322 DNA, and used to transform E . coli RR1 . Tetracycline-resistant bacterial colonies were screened for the presence of plasmid containing the copied HA gene by testing their ability to hybridise to a specific, 32P-labelled, single-stranded DNA probe . Four cloned hybrid plasmids, containing DNA complementary to the HA gene of the influenza strain 29C (a laboratory derivative of influenza A/NT/60/68 (1)) were analysed by restriction enzyme mapping . Each contained a dsDNA insert equivalent to a full length copy of the HA gene . The nucleotide sequence of a selected restriction fragment from the DNA inserted in one of these cloned plasmids (C89) was determined . The amino acid sequence deduced from these data agreed with the amino acid sequence determined for the corresponding region of HA from the influenza strain A/Mem/102/72, another member of the Hong Kong subtype, identifying the inserted dsDNA of C89 as an authentic copy of the influenza HA gene.

J Biol Chem, 1979 Oct 25, 254(20), 9979 - 81
Precursor maltose-binding protein is active in binding substrate; Ferenci T et al.; Precursor maltose-binding protein synthesized in vitro was shown to be active in binding maltose by affinity chromatography.

J Biol Chem, 1979 Oct 25, 254(20), 10237 - 42
The 6-phosphogluconate dehydrogenase reaction in Escherichia coli; de Silva AO et al.; This study is an attempt to relate in vivo use of the 6-phosphogluconate dehydrogenase reaction in Escherichia coli with the characteristics of the enzyme determined in vitro . 1) The enzyme was obtained pure by affinity chromatography and kinetically characterized; as already known, ATP and fructose-1,6-P2 were inhibitors . 2) A series of isogenic strains were made in which in vivo use of thereaction might differ, e.g . a wild type strain versus a mutant lacking 6-phosphogluconate dehydrase, as grown on gluconate; a phosphoglucose isomerase mutant grown on glucose or glycerol . 3) The in vivo rate of use of the 6-phosphogluconate dehydrogenase reaction was determined from measurements of growth rate and yield and from the specific activity of alanine after growth in 1-14C-labeled substrates . 4) The intracellular concentrations of 6-phosphogluconate, NADP+, fructose-1,6-P2, and ATP were measured for the strains in growth on several carbon sources . 5) The metabolite concentrations were used for assay of the enzyme in vitro . The results allow one to calculate how fast the reaction would function in vivo if ATP and fructose-1,6-P2 were its important effectors and if the in vitro assay conditions apply in vivo . The predicted in vivo rates ranged down to as low as one-tenth of the actual rates, and, accordingly, one cannot yet draw firm conclusions about how the reaction is actually controlled in vivo.

J Biol Chem, 1979 Oct 25, 254(20), 10139 - 44
The hydrodynamic shape, conformation, and molecular model of Escherichia coli ribosomal 5 S RNA; Fox JW et al.; The structure of ribosomal 5 S RNA has been examined using several physical biochemical techniques . Hydrodynamic measurements yield a s020,omega and {eta} of 5.5 x 10(-13) x and 6.9 ml/g, respectively . Other parameters calculated from these values indicate the shape of 5 S RNA is consistent with that of a prolate ellipsoid 160 A in length and 32 A wide . Sedimentation equilibrium results show that 5 S RNA exists as a monomer in the reconstitution buffer with an apparent molecular weight of 44,000 . Ultraviolet absorption difference spectra show that approximately 75% of the bases in 5 S RNA are involved in base pairing, and of these base pairs 70% are G-C and 30% are A-U . These results on the overall shape and secondary structure of 5 S RNA have been incorporated with the results of other investigators as to the possible location of single-stranded and double-stranded helical regions, and a molecular model for 5 S RNA is proposed . The molecular model consists of three double helices in the shape of a prolate ellipsoid, with two of the double helical regions at one end of the molecule . The structure is consistent with the available data on the structure and function of 5 S RNA and bears similarity to the molecular model proposed by Osterberg et al . ((1976) Eur . J . Biochem . 68, 481-487) based on small angle x-ray scattering results and the secondary structure proposed by Madison ((1968) Annu . Rev . Biochem . 37, 131-148).

J Biol Chem, 1979 Oct 25, 254(20), 10128 - 34
High resolution thermal denaturation analyses of small sequenced DNA restriction fragments containing Escherichia coli lactose genetic control loci; Hardies SC et al.; Differential melting curves are reported for four DNA restriction fragments (789, 301, 203, and 95 base pairs in length) spanning the lactose control region . All but the smallest melt with two or more subtransitions . Maps are proposed which identify the positions of regions of different thermal stability in the sequences . The sizes of regions comprising subtransitions range from 60 to 200 base pairs . An analysis is made of the cooperativity exhibited between regions in the sequence . The effect on the shape of the differential melting curves of Na+ between 10 mM and 0.5 M as well as that of Mg2+ and glycerol has been determined . An 81-bp-long sequence of unusual thermal stability occurs at the lactose promoter . Its TM change, resulting from the above change in salt concentration, is out of step by 1.5 degree C with the neighboring DNA sequence . The potential biological significance of this behavior is discussed.

Nucleic Acids Res, 1979 Oct 25, 7(4), 859 - 77
Hybrid plasmids containing an active thymidine kinase gene of Herpes simplex virus 1; Wilkie NM et al.; The gene for the thymidine kinase (TK) of Herpes simplex virus type 1 (HSV-1) is located in the KpnI m and BamHI p fragments of the genome (Wigler et al., Cell 11, 223-232 (1977)) . These fragments have been inserted into the EcoRI and BamHI sites, respectively, of plasmid pBR322, and propagated in E.coli . The TK gene contained in the recombinant plasmids was shown to be biologically active when introduced into TK- mouse L cells . Detailed restriction site maps of the BamHI p fragment have been constructed and the approximate location of the TK gene has been determined . Mouse cells transformed with cloned HSV-1 tk+ DNA produced HSV-1-specific thymidine kinase; superinfection with HSV-1 tk- virus increased the level of TK activity tenfold, suggesting that the BamHI p sequences present in transformed cells respond to virus-encoded regulatory gene product(s).

J Biol Chem, 1979 Oct 25, 254(20), 10449 - 52
Phosphorylation of 5-iodo-5'-amino-2',5',dideoxyuridine by herpes simplex virus type 1 encoded thymidine kinase; Chen MS et al.; Herpes simplex virus type 1 (HSV-1) encoded thymidine kinase converts 5-iodo-5'-amino-2',5'-dideoxyuridine (AIdUrd), a highly specific anti-herpes agent, into the 5'-diphosphate (AIdUDP) derivative in vitro . AIdUDP was identified by its acid lability, sensitivity to alkaline phosphatase hydrolysis, chromatographic behavior, and ratio of double isotope (125I, 32P) labeling . ATP, but not AMP, is a phosphate donor, and the direct transfer of the beta and gamma phosphate of ATP as pyrophosphate to AIdUrd was ruled out . The presence of a phosphoramidate bond was supported by the acid lability of AIdUDP which has a half life (t1/2) of 320 min at pH 3.0 . At neutral pH, the hydrolysis products are AIdUrd and orthophosphate, with AIdUrd monophosphate being the probable hydrolytic intermediate at these pH values . However, at acidic pH, some pyrophosphate was detected in addition to AIdUrd and orthophosphate . AIdUrd competitively inhibited the phosphorylation of thymidine and deoxycytidine . Escherichia coli thymidine kinase, even though 100-fold higher in activity, was unable to phosphorylate AId-Urd under similar incubation conditions.

Nature, 1979 Oct 25, 281(5733), 704 - 6
Ribonucleotides in DNA newly synthesised in 3T6 cells in vivo; Kowalski J et al.; Within the field of DNA replication, considerable interest has focused in recent years on the mechanism of initiation of synthesis of DNA molecules . In vitro replication systems from Escherichia coli have been instrumental in uncovering a priming function fo9r ribonucleotides on the earliest intermediates of DNA polymerisation in vitro and in identifying the proteins involved . In vitro replication systems from mammalian cells that permit the use of the phosphate-transfer method for detection of RNA-DNA junctions as well as direct labelling of the RNA moiety of the molecules have suggested a similar role for ribonucleotides in DNA synthesis in eukaryotes . However, the existence of this mechanism in mammalian cells in vivo has not been established . Here we report the first evidence that a significant proportion of the earliest intermediates in mammalian DNA polymerisation in vivo do, in fact, possess ribonucleotides, presumably because their synthesis was initiated with one or more ribonucleotides.

Biochim Biophys Acta, 1979 Oct 24, 580(2), 289 - 97
Studies on the subunits of Escherichia coli coenzyme A transferase . Reconstitution of an active enzyme; Frerman FE et al.; The alpha and beta subunits of the acetyl-CoA:acetoacetate-CoA transferase were purified by isoelectric focusing of the enzyme in the presence of 6 M urea . The purified beta subunit, in which the active center of the enzyme is located, exhibits low catalytic activity (2% of the specific activity of the native enzyme) which is stimulated 5-6-fold in the presence of an equimolar concentration of alpha subunit . The presence of the substrate,acetoacetyl-CoA, is required to recover the catalytic activity of the beta subunit and mixtures containing purified alpha and beta subunits . When the enzyme is dissociation in the presence of 6 M urea and the subunits are not fractioned, removal of the urea by dialysis results in the recovery of 88-98% of enzymic activity and the native alpha2beta2 subunit structure . However, analysis of this renatured enzyme by immunochemical techniques shows that the enzyme does not refold to a completely native conformation . This renatured enzyme exhibits an immunological reactivity more closely resembling the isolated alpha subunit . The results indicate that the alpha subunit serves as a structural subunit, or possible a maturation subunit, imposing a conformation on the beta subunit that is catalytically more competent.

Nature, 1979 Oct 18, 281(5732), 544 - 8
Direct expression in Escherichia coli of a DNA sequence coding for human growth hormone; Goeddel DV et al.; DNA coding for human growth hormone was constructed by using chemically synthesised DNA in conjunction with enzymatically prepared cDNA . This 'hybrid' gene was expressed in Escherichia coli under the control of the lac promoter . A polypeptide was produced having the size and immunological properties characteristic of mature human growth hormone.

Eur J Biochem, 1979 Oct 15, 100(2), 399 - 410
The complete nucleotide sequence of the ribosomal 16-S RNA from Excherichia coli . Experimental details and cistron heterogeneities; Carbon P et al.; The complete nucleotide sequence of the 16-S RNA from Escherichia coli has been determined using rapid RNA-sequencing gel methods . The experimental data are fully described in this paper . The specificities of the ribonucleases, especially the ribonuclease PhyI are discussed and the consequences of the persistence of stable secondary structure are considered . The proposed sequence contains 1541 nucleotides and agrees completely with the DNA sequence of the rrnB cistron deduced by Brosius, J., Palmer, M.L., Kennedy, P.J., and Noller, H.F . {Proc . Natl . Acad . Sci . U.S.A . (1978) 75, 4801-4805} . But there are several cistron heterogeneities of which we described 16 single-base heterogeneities, 7 of the deletion/insertion type and 9 of the transition or transversion type . Our observations suggest the existence, among the 7 ribosome RNA cistrons, of one or two mutated ones . The respective advantages and disadvantages of both RNA and DNA sequencing methods are discussed.

Eur J Biochem, 1979 Oct 15, 100(2), 321 - 8
Arrangement of proteins O-8 and O-9 in outer membrane of Escherichia coli K-12 . Existence of homotrimers and heterotrimers; Ichihara S et al.; 1 . The molecular arrangement of major outer membrane proteins O-8 and O-9 that exist as trimers has been studied by means of cross-linking with dimethylsuberimidate . 2 . The cross-linked samples were examined on a urea/sodium dodecyl sulfate/polyacrylamide gel which was developed to separate cross-linked trimer and dimer of O-8 from those of O-9 . 3 . Cells simultaneously synthesizing both O-8 and O-9 formed heterotrimers (trimers containing both proteins) as well as homotrimers . 4 . Quantitative analyses revealed that there was no discrimination between O-8 and O-9 in the assembly process to form trimers . 5 . When cells were grown sequentially under two different sets of conditions so that the cells synthesized either one of the two proteins in the first stage and the other in the second stage of growth, no heterotrimers were formed . This result indicates that subunit exchange did not take place between trimers which had been incorporated into the outer membrane.

Experientia, 1979 Oct 15, 35(10), 1398 - 400
Colony stimulating activity in acute and chronic endotoxinemia in man; Hinterberger W et al.; Blood granulocyte-macrophage colony stimulating activity (GM CSF) was measured in 6 normal individuals challenged with low-dose endotoxin and in 63 unselected patients with nonhaematological disorders . 5/63 patients were febrile and 5 other patients whoed detectable endotoxin levels, as measured by the Limulus assay . CSA levels showed a rapid increase in normal individuals following endotoxin administration, but were in the normal range in patients with chronic endotoxinemia or in those with febrile disorders . Thus, unlike acute endotoxinemia, chronic endotoxinemia is not associated with elevated activity that promotes growth of myeloid commited stem cells . In addition, fever per se did not coincide with elevated blood CSA levels.

Tijdschr Diergeneeskd, 1979 Oct 15, 104(20), suppl 4:169 - 75
Detection of the K99 antigen of Escherichia coli in calf faeces by enzyme-linked immunosorbent assay (ELISA); Ellens DJ et al.; An enzyme-linked immunosorbent assay (ELISA) is presented for the detection of the K99 antigen of Escherichia coli in calf faeces . False-positive reactions were not observed with K99-negative strains and with several viral antigens . Only bovine coronavirus caused slight positive reactions which could be eliminated by a blocking test . As compared with the conventional procedure for the detection of the K99 antigen, ELISA seemed to be a least as sensitive and had the advantage that samples could be stored at --20 degrees C before testing . In addition many samples could be handled at the same time and the results became available quickly . By carrying out the assay as a blocking test, specific antibody against K99 in serum or colostrum could be detected and titrated.

Experientia, 1979 Oct 15, 35(10), 1318 - 20
Mg2+-ATPase defective mutant of Escherichia coli and thiamine transport; Nishimune T et al.; Mg2+-ATPase deficient mutant of Escherichia coli showed an evident dependency of thiamine uptake on the oxidative metabolism of glucose, whereas the parent strain did not . In both cells, this uptake was completely inhibited by H+ conductors.

Biochem J, 1979 Oct 15, 184(1), 13 - 21
Linked transport of phosphate, potassium ions and protons in Escherichia coli; Russell LM et al.; Pi entry into Escherichia coli cells through either of the two Pi-transport systems (Pit or Pst) prompts the influx of K+ and H+ in a ratio that depends on the external pH . The entry of Pi is absolutely dependent on the presence of K+, and the entry of K+ is equally dependent on the presence of Pi . Experiments with a number of mutants carrying any one functional Pi-transport system and one or more of the individual K+-transport systems indicate a permissive type of linkage of the two transports, in that there is no obvious preference by any of the Pi-transport systems for a particular K+-transport system for the concomitant entry of the two ions.

Biochim Biophys Acta, 1979 Oct 11, 570(2), 248 - 58
Two forms of pyruvate kinase in Escherichia coli . A comparison of chemical and molecular properties; Valentini G et al.; The two forms of pyruvate kinase (ATP:pyruvate 2-O-phosphotransferase, EC 2.7.1.40) present in Escherichia coli have been purified from the same cultures and crystallized . A modified procedure for the purification of type I pyruvate kinase is described . Molecular weight, subunit structure, amino acid composition, NH2-terminal amino acid, maps of tryptic peptides and conditions for crystallization have been determined for the two forms . A comparison of these data shows that the two forms are different proteins, each being a tetramer of identical subunits.

Nature, 1979 Oct 11, 281(5731), 447 - 52
Directive segregation in the basis of colE1 plasmid incompatibility; Bedbrook JR et al.; Incompatibility between colE1 plasmids in Escherichia coli can be explained by competition for a limited number of replication sites . These sites ensure directive segregation of plasmids to daughter cells on cell division . The number of sites can be more than one only if a linear segregation mechanism is postulated.

Nucleic Acids Res, 1979 Oct 10, 7(3), 735 - 49
A rhelogical separator for very large DNA molecules; Dill KA et al.; We present a rheological separation method for DNA molecules in which their deformability is used to advantage . This is the "radial migration method"; here we present experimental verification of the principle, theory having been reported elsewhere . The main conclusions are: (1) the theory is reasonably good; (2) radial migration is highly sensitive to the molecular weight, as predicted, and (3) intact T2 DNA (1.25 X 108 daltons) can be made to migrate about three centimeters in less than three hours.

Nucleic Acids Res, 1979 Oct 10, 7(3), 639 - 49
Gene expression in vitro of colicin El plasmid; Ebina Y et al.; Among eighteen polypeptides synthesized in vitro from colicin El plasmid, one of the major products with a molecular weight of 59,000 was identified as colicin El by its immunological property, molecular size, and biological activity . In addition to this polypeptide, seven other polypeptides reacted with colicin El antiserum . Using EcoRI-cleaved colicin El DNA, a 56,000 dalton polypeptide of truncated colicin El was synthesized, but no polypeptide that reacted with colicin El antiserum was produced from SmaI-cleaved colicin El DNA . This fact indicates that the direction of transcription of colicin El structural gene is from SmaI site to EcoRI site in vitro . The immunity protein of a molecular weight of 14,300 and a component of relaxation proteins of a molecular weight of 64,000 were deduced by comparing the results of the gene expression in vitro of one-half (pAO100) and a quarter (pAO2) of colicin El plasmid . The directions of transcription-translation in the genes on the plasmid were discussed . The colicin El plasmid appears to have at least three transcriptional units.

J Biol Chem, 1979 Oct 10, 254(19), 9800 - 6
Identification of the amino acid residues of proteins S5 and S8 adjacent to each other in the 30 S ribosomal subunit of Escherichia coli; Allen G et al.; When Escherichia coli 30 S ribosomal subunits are reacted with protein-protein bifunctional reagents, a number of protein pairs as well as aggregates containing three or more ribosomal proteins are formed . In the present study we have purified one of the protein pairs obtained by reaction of 30 S ribosomal subunits with either radioactive or nonradioactive dimethylsuberimidate . Following molecular weight determination and ammonolysis, the pair was shown to consist of ribosomal proteins S5 and S8 . The "native" structure of the complex was surmised from its capacity to be reconstituted into a biologically active 30 S ribosomal subunit . From peptide maps and primary structure determination of various peptides it was demonstrated that the cross-linking bond between ribosomal proteins S5 and S8 involves primarily the residues Lys-93 of protein S8 and the COOH-terminal lysine (Lys-166) of ribosomal protein S5 . This result is substantiated by the finding that a mutant carrying an altered S5 lacking the COOH-terminal lysine yields a greatly reduced amount of S5-S8 cross-link . In addition to the points of cross-linking it was found that Lys-30, Lys-68, and Lys-86 of S8 and Lys-5 of S5 react with dimethylsuberimidate, indicating that these residues are available for reaction and suggesting their topographical localization on the ribosomal surface.

J Biol Chem, 1979 Oct 10, 254(19), 9627 - 32
Thioredoxin catalyzes the reduction of insulin disulfides by dithiothreitol and dihydrolipoamide; Holmgren A; Thioredoxin from Escherichia coli was shown to catalyze the reduction of insulin disulfides by dithiothreitol . A quantitative assay was developed which measures the rate of insulin reduction spectrophotometrically at 650 nm as turbidity formation from the precipitation of the free insulin B chain . Thioredoxin, at 5 microM concentration, accelerated the reaction between 0.130 mM insulin and 1.0 mM dithiothreitol at pH 7 around 20-fold . The pH optimum of the reaction was 7.5 . Thioredoxins from E . coli and calf liver showed similar specific activities . Stopped flow fluorescence measurements of the rate of reduction of thioredoxin-S2 by dithiothreitol showed a second order rate constant of 1647 M-1 s-1 at pH 7.2 . This is between 10(2) to 10(3) times larger than the reaction between insulin or linear model disulfides and dithiothreitol . It is consistent with a ping-pong mechanism of thioredoxin catalysis since reduced thioredoxin is known to react very fast with insulin . Thioredoxin also catalyzed lipoamide-dependent reduction of the insulin disulfides in a coupled system with NADH, lipoamide, and lipoamide dehydrogenase . The fast spontaneous reaction between dihydrolipoamide and thioredoxin-S2 provides a mechanism for NADH or pyruvate-dependent disulfide reduction . The implication of the dithiol-disulfide oxidoreductase activity of thioredoxin for the regulation of enzyme activities by thiol oxidation-reduction control is discussed.

J Biol Chem, 1979 Oct 10, 254(19), 9429 - 40
ilvU, a locus in Escherichia coli affecting the derepression of isoleucyl-tRNA synthetase and the RPC-5 chromatographic profiles of tRNAIle and tRNAVal; Fayerman JT et al.; A mutation in the ilvU locus of Escherichia coli has led to a complex phenotype that included resistance to thiaisoleucine, a loss of derepressibility of isoleucyl tRNA synthetase, and an alteration of the RPC-5 chromatographic profile of the branched-chain aminoacyl-tRNA's . The alterations were manifest in an increase in the amount of Species 2 of both tRNAIle and tRNAVal at the expense of Species 1 . A similar alteration, but independent of (and additive to) that caused by the ilvU mutation, was observed upon limitation of either isoleucine or valine . The shift in profile caused by limitation was also independent of the reduced growth rate or the derepression of the isoleucine and valine biosynthetic enzymes that also result from limitation . During chloramphenicol treatment nearly all tRNAIle and tRNAVal formed appears as species 2 . Upon recovery from chloramphenicol, Species 2 of both acceptors are converted to Species 1 . It is proposed that the ilvU product not only allows derepression of isoleucyl-tRNA synthetase but also retards the conversion of tRNA2Ile to tRNA1Ile and that of tRNA2Val to tRNA1Val . The mutated ilvU loci abolish the derepression and are more efficient in retarding the conversion.

Nucleic Acids Res, 1979 Oct 10, 7(3), 689 - 703
Analysis of RNA secondary structure by photochemical reversal of psoralen crosslinks; Rabin D et al.; Aminomethyltrioxsalen (AMT), a psoralen, is known to cause interstrand crosslinks in double stranded nucleic acids . We have demonstrated the photochemical reversal of this reaction, and have used this result to develop a method for identification of specific sequences which are adjacent because of RNA secondary structure formation . E . coli 5S rRNA is used as a model system . We isolated and characterized a product that is derived from the stem region of 5S RNA.

Nucleic Acids Res, 1979 Oct 10, 7(3), 547 - 69
Review: ethidium fluorescence assays . Part 1 . Physicochemical studies; Morgan AR et al.; DNA and RNA can be assayed rapidly and very sensitively by exploiting the enhanced fluorescence of ethidium intercalated into duplex regions . By assaying at different pHs and introducing a heating/cooling cycle, a great many physicochemical aspects of DNA and RNA can be studied avoiding the use of radiolabels, and often giving information not otherwise readily obtainable . Studies are described on duplex DNA which involve measurement of extinction coefficients, cross-linking by chemicals, Cot curve analysis as well as estimation of drug-DNA binding constants . The assays can be adapted to investigate multi-stranded nucleic acid structures . The use of covalently closed circular DNA also allows rapid and extremely sensitive measurements of nicking caused by irradiation or drugs.

Med J Aust, 1979 Oct 6, 2(7), 376 - 8
Suppurative pyephlebitis and multiple hepatic abscesses with silent colonic diverticulitis; Waxman BP et al.; This report records the first known case in the literature of suppurative pylephlebitis associated with multiple intrahepatic and extrahepatic abscesses and gross hypoalbuminaemia, as a consequence of colonic diverticulitis.

Mol Gen Genet, 1979 Oct 3, 176(2), 233 - 8
IS2-61 and IS2-611 arise by illegitimate recombination from IS2-6; Ghosal D et al.; A more stable derivative of IS2-6 has been isolated, which had lost 54 bp of the 108 bp long insert characteristic of IS2-6 . This new allele of IS2, IS2-61, segregates the remaining 54 bp to yield allele IS2-611 . DNA sequence analysis shows that the segregation products of IS2-6 arise by recA-independent, illegitimate recombination at 9 bp long direct sequence repetitions.

Mol Gen Genet, 1979 Oct 3, 176(2), 183 - 9
The DNA-protein relaxation complex of the plasmid RK2: location of the site-specific nick in the region of the proposed origin of transfer; Guiney DG et al.; The broad jost range plasmid, RK2, has been isolated as a DNA-protein relaxation complex . Nicking of the plasmid DNA in the relaxation complex occurs at a single specific site (rlx) located approximately 20 kb away from the origin of DNA replication . A cis-acting function required for plasmid transfer, the presumptive origin of transfer, maps in the same region as rlx . The region of RK2 encompassing rlx has been cloned onto pBR322 and shown to promote mobilization of the hybrid plasmid by an RK2 derivative . These results indicate that the RK2 relaxation complex nicks at or near the origin of transfer of the RK2 plasmid.

Mol Gen Genet, 1979 Oct 3, 176(2), 161 - 70
Nucleotide sequence of the region required for maintenance of colicin E1 plasmid; Ohmori H et al.; Plasmids carrying various portions of colicin E1 plasmid (ColE1) DNA have been isolated in an attempt to determine the regions of ColE1 DNA which are required for maintenance of the plasmid in bacteria . To construct the plasmids, the DNA of a ColE1 derivative that contains a gene which controls ampicillin resistance was cleaved by the restriction endonuclease HaeII . The digestion products were joined by T4 DNA ligase and then used to transform bacteria to ampicillin resistance . The plasmid derivatives obtained in this way were always composed of certain HaeII segments . These contain approximately 10% of the ColE1 genome and include the origin of replication of ColE1 . We presume that the region of ColE1 which is common to all these derivatives is required for maintenance of the plasmid . After a description of these results, the nucleotide sequence of this region is presented, and possible roles of the region in plasmid replication and maintenance are discussed.

Mol Gen Genet, 1979 Oct 3, 176(2), 209 - 19
Amplification of chloramphenicol resistance transposons carried by phage P1Cm in Escherichia coli; Meyer J et al.; We have characterized a number of P1Cm phages which contain the resistance genes to chloramphenicol and fusidic acid as IS1-flanked Cm transposons . Restriction cleavage and electron microscopic analysis showed that these Cm transposons were carried as monomers (M) or tandem dimers (D) . Lysogens of P1Cm (D) are more resistant to chloramphenicol than those of its P1Cm (M) presumably as a result of an increased gene dosage . Amplification of the Cm transposons to tandem multimers was frequently observed in P1Cm (D) lysogens grown in the presence of high concentrations of chloramphenicol or fusidic acid and was also detected in P1Cm (M) lysogens . The degree of amplification varied in different clones which suggests that cells containing spontaneously amplified Cm transposons were selected by high doses of the antibiotics . The dimeric as well as the amplified Cm transposons carried in P1Cm lysogens grown in the absence of chloramphenicol displayed considerable stability . Mechanisms for the amplification of the IS1-flanked transposons are discussed.

Mol Gen Genet, 1979 Oct 2, 176(1), 147 - 9
Identification of a mutation affecting an alanine-alpha-ketoisovalerate transaminase activity in Escherichia coli K-12; Falkinham JO 3rd; A mutation affecting alanine-alpha-ketoisovalerate transaminase activity has been shown to be cotransducible with ilv gene cluster . The transaminase deficiency results in conditional isoleucine auxotrophy in the presence of alanine.

Mol Gen Genet, 1979 Oct 2, 176(1), 139 - 46
ColE1 DNA sequences interacting in cis, essential for mitomycin-C induced lethality; Shafferman A et al.; Protein synthesis and survival of colicinogenic bacteria carrying different ColE1 deletion and insertion mutants, were followed in presence or absence of the inducing agent mitomycin-C . It is concluded that active colicin is not involved in the process leading to death of the induced colicinogenic cell . The region of ColE1, essential for cell induced lethality, is carried on the DNA between map positions 0.74 to 0.27 . In this region the DNA sequences carried between 0.74 to 0.79 and 0.0 to 0.27 are essential, while those located between 0.79 to 0.0 are nonessential for commitment to death . A cis interaction of the ColE1 DNA sequences in the essential regions is probably necessary for cell induced lethality . Some possibilities for such a cis interaction are suggested and discussed.

Mol Gen Genet, 1979 Oct 2, 176(1), 105 - 11
A cold-sensitive beta subunit mutant RNA polymerase from Escherichia coli with defects in promoter opening in vitro; Larionov OA et al.; A cold-sensitive mutation in the rpoB gene for the RNA polymerase beta subunit increasing the temperature of promoter opening on T2 phage DNA was obtained in Escherichia coli . The mutation also affects the stages preceding promoter opening by increasing the dissociation rate of RNA polymerase--DNA closed complexes . The affinity of RNA polymerase to T2 and lambda DNA is differentially changed by the mutation . The relative efficiency of transcription of these two templates is also changed . These results suggest a participation of the RNA polymerase beta subunit in the interaction with promoters.

Mol Gen Genet, 1979 Oct 2, 176(1), 1 - 9
Induction of UV-resistant DNA replication in Escherichia coli: induced stable DNA replication as an SOS function; Kogoma T et al.; The striking similarity between the treatments that induce SOS functions and those that result in stable DNA replication (continuous DNA replication in the absence of protein synthesis) prompted us to examine the possibility of stable DNA replication being a recA+ lexA+-dependent SOS function . In addition to the treatments previously reported, ultraviolet (UV) irradiation or treatment with mitomycin C was also found to induce stable DNA replication . The thermal treatment of tif-1 strains did not result in detectable levels of stable DNA replication, but nalidixic acid readily induced the activity in these strains . The induction of stable DNA replication with malidixic acid was severely suppressed in tif-1 lexA mutant strains . The inhibitory activity of lexA3 was negated by the presence of the spr-51 mutation, an intragenic suppressor of lexA3 . Induced stable DNA replication was found to be considerably more resistant to UV irradiation than normal replication both in a uvrA6 strain and a uvr+ strain . The UV-resistant replication occurred mostly in the semiconservative manner . The possible roles of stable DNA replication in repair of damaged DNA are discussed.

Chromosoma, 1979 Oct 2, 75(1), 63 - 74
Localization of satellite DNAs in the chromosomes of the guinea pig; Duhamel-Maestracci N et al.; The in situ hybridization method has been used to investigate the localization of each of the three satellite DNAs present in the genome of the guinea pig . Purified fractions of the satellite DNAs were utilized as templates for synthesis of 3H-labeled complementary RNA (cRNA) by E . coli RNA polymerase, then each cRNA was hybridized to metaphase spreads of embryonic guinea pig cells . The cRNAs of all three satellite DNAs hybridized predominantly to the centromeric region of the chromosomes . The cRNAs of satellite DNAs II and III hybridized to all chromosomes except the Y chromosome . The cRNA of satellite DNA I did not hybridize to the Y chromosome nor to two pairs of small acrocentric chromosomes . Satellite II cRNA hybridized to the telomeric region of chromosomes 3 and 4.

Mol Gen Genet, 1979 Oct 2, 176(1), 121 - 8
A kinetic analysis of cell division, and induction and stability of recA protein in U.V . Irradiated ion+ and ion-strains of Escherichia coli K12; Darby V et al.; Kinetic analysis of induction of recA protein synthesis after U.V . irradiation does not show correspondence with the kinetics of division inhibition in ion+ and ion- strains . When the induction of recA protein after U.V . is drastically reduced by rifampicin treatment, no effect on the kinetics of division inhibition is observed.

Mol Gen Genet, 1979 Oct 2, 176(1), 113 - 20
Transposon 10 promoted deletions and inversions in the transfer genes of R100-1; Kehoe MA et al.; Spontaneous tetracycline-sensitive, transfer-deficient mutants of R100-1 were selected and analysed by genetic complementation tests and with the restriction endonuclease EcoR1 . While some of the Tets Tra- mutants were caused by a single deletion event which removed the Tetr genes and extended into the neighbouring transfer genes, other mutants were the result of the deletion of the Tetr genes within Tn10 which was accompanied by an inversion of adjacent DNA sequences . A clustering of deletion and inversion endpoints occurred in the traA gene . Some of the transfer genes of R100-1 were assigned to EcoR1 fragments.

Biochemistry, 1979 Oct 2, 18(20), 4431 - 43
Involvement of eucaryotic deoxyribonucleic acid polymerases alpha and gamma in the replication of cellular and viral deoxyribonucleic acid; Krokan H et al.; In an effort to identify the deoxyribonucleic acid (DNA) polymerase activities responsible for mammalian viral and cellular DNA replication, the effect of DNA synthesis inhibitors on isolated DNA polymerases was compared with their effects on viral and cellular DNA replication in vitro . DNA polymerase alpha, simian virus 40 (SV40) DNA replication in nuclear extracts, and CV-1 cell (the host for SV40) DNA replication in isolated nuclei all responded to DNA synthesis inhibitors in a quantitatively similar manner: they were relatively insensitive to 2',3'-dideoxythymidine 5'-triphosphate (d2TTP), but completely inhibited by aphidicolin, 1-beta-D-arabinofuranosylcytosine 5'-triphosphate (araCTP), and N-ethylmaleimide . In comparison, DNA polymerases beta and gamma were inhibited by d2TTP but insensitive to aphidicolin and 20--30 times less sensitive to araCTP than DNA polymerase alpha . Herpes simplex virus type 1 (HSV-1) DNA polymerase and DNA polymerase alpha were the only enzymes tested that were relatively insensitive to d2TTP; DNA polymerases beta and gamma, phage T4 and T7 DNA polymerases, and Escherichia coli DNA polymerase I were 100--250 times more sensitive . The results with d2TTP were independent of enzyme concentration, primer-template concentration, primer-template choice, and the labeled dNTP . A specific requirement for DNA polymerase alpha in the replication of SV40 DNA was demonstrated by the fact that DNA polymerase alpha was required, in addition to other cytosol proteins, to reconstitute SV40 DNA replication activity in N-ethylmaleimide-inactivated nuclear extracts containing replicating SV40 chromosomes . DNA polymerases beta and gamma did not substitute for DNA polymerase alpha . In contrast to SV40 and CV-1 DNA replication, adenovirus type 2 (Ad-2) DNA replication in isolated nuclei was inhibited by d2TTP to the same extent as gamma-polymerase . Ad-2 DNA replication was also inhibited by aphidicolin to the same extent as alpha-polymerase . Synthesis of CV-1 DNA, SV40 DNA, and HSV-1 DNA in intact CV-1 cells was inhibited by aphidicolin . Ad-2 DNA replication was also inhibited, but only at a 100-fold higher concentration . We found no effect of 2'-3'-dideoxythymidine (d2Thd) on cellular or viral DNA replication in spite of the fact that Ad-2 DNA replication in isolated nuclei was inhibited 50% by a ratio of d2TTP/dTTP of 0.02 . This was due to the inability of CV-1 and Hela cells to phosphorylate d2Thd to d2TTP . These data are consistent with the hypothesis that DNA polymerase alpha is the only DNA polymerase involved in replicating SV40 DNA and CV-1 DNA and that Ad-2 DNA replication involves both DNA polymerases gamma and alpha.

Biochemistry, 1979 Oct 2, 18(20), 4270 - 7
Purification of the messenger ribonucleic acid for the lipoprotein of the Escherichia coli outer membrane; Wang SS et al.; The mRNA for the lipoprotein of the Escherichia coli outer membrane has been purified to 85% homogeneity . The purification procedure involved phenol extraction, NaCl extraction, gel filtration on Sephadex G-100 and Sephadex G-200, and reversed-phase column chromatography on RPC-5 . The purity of the final product was estimated to be 85% by analysis of the ribonuclease T1 fingerprint of the mRNA . The purified mRNA was able to direct the synthesis of cross-reactive material with antilipoprotein serum in both the E . coli and the wheat germ cell-free protein-synthesizing systems . The size of the mRNA was determined to be 8.2 S from its mobility in polyacrylamide--agrose gels . During the purification, two other RNA species, similar in size to the lipoprotein mRNA, were also isolated . Their sizes were determined to be 8.7 and 9.1 S . They both were inactive in an E . coli cell-free protein-synthesizing system.

Neurochem Res, 1979 Oct, 4(5), 557 - 65
Age-dependent changes in the specificity of tRNA methyltransferases in the cerebellum of the icteric and nonicteric Gunn rat; Dainat J et al.; The activity of tRNA methyltransferases present in the cerebellum of 6- and 21-day-old nonicteric and icteric Gunn rats was compared using purified E . coli tRNAs as substrates . At 6 days the tRNA methyltransferases of the icteric animals were significantly more effective in methylating tRNAGlu2 and tRNAPhe than were those of their nonicteric counterparts . This relationship reversed itself at 21 days . The action of the tRNA methyltransferases from the 6-day-old icteric animals led to higher proportions of 1-methyladenine in tRNAGlu2 and tRNAPhe than were obtained using the corresponding enzymes of the nonicteric animals . The proportion of N2-methylguanine was also higher, yet only in tRNAfMet and not in tRNAPhe . The study reveals much more extensive fluctuations in the activity and in the substrate recognition specificity among the cerebellar tRNA methyltransferases of the icteric than among those of the nonicteric controls during the crucial 6--21 day period of cerebellar development.

J Nutr, 1979 Oct, 109(10), 1815 - 23
The effect of vitamin A deficiency on the in vitro cellular immune response of rats; Nauss KM et al.; The effect of vitamin A deficiency on the response of splenic lymphocytes to mitogenic stimulation was determined in an experimental rat model . Male Lewis rats were divided into three groups . The ad libitum group (AL) was fed unlimited amounts of a vitamin A-supplemented diet . The vitamin A-deficient group (DEF) received a commercial vitamin A-free diet . The pair-fed group (PF) received a vitamin A-containing diet equivalent in amount to that consumed by the DEP group . During the early stages of vitamin A deficiency (determined by cessation of weight gain), the rats were killed and the isolated splenic lymphocytes subjected to mitogenic stimulation . Lymphocytes from DEF rats had one-third the transformation response to the mitogens Concanavalin A, Phytohemagglutinin and E . coli Lipopolysaccharide S of the AL and PF groups . When the DEF rats were supplemented with vitamin A, the transformation response returned to control values within 3 days . In addition to the alterations in the immune response, the DEF rats showed a marked leukopenia, a decrease in the number of circulating lymphocytes and an increase in the number of circulating neutrophils.

Eur J Biochem, 1979 Oct, 100(1), 245 - 55
A restriction map of cauliflower mosaic virus DNA (strain PV 147) . Mapping of the cleavage sites of HhaI, SacI, AvaI, PvuII, PstI, XbaI, EcoRI, Bg/II, HincII, HpaII and HindII + III; Volovitch M et al.; The virion-extracted DNA (Mr5 x 10(6)) of cauliflower mosaic virus (CaMV) has three single-stranded interruptions . The mapping of this DNA using eleven restriction endonucleases (HhaI, SacI, AvaI, PvuII, PstI, XbaI, EcoRI, Bg/II, HincII, HpaII and HindII + III) is reported here . The existence of the three single-stranded breaks complicates the identification and the molecular weight determination of fragments produced by HpaII, HindIII and HindII + III . Indeed the electrophoretic mobility of some fragments in which a single-stranded discontinuity is located is modified, and the fluorescence of ethidium bromide complexed with these fragments is reduced as compared to that observed for the other fragments existing in a molar ratio . These drawbacks were overcome by performing experiments of nick-translation of CaMV DNA with Escherichia coli DNA polymerase I . FRom the data it follows that the CaMV DNA molecule bears bears 1 site for HhaI and SacI, 2 for AvaI and PvuII, 3 for PstI, 4 for XbaI, 5 for EcoRI, 6 for Bg/II and HincII, 11 for HpaII and 15 for HindII + III . The corresponding fragments have all been ordered and precisely located providing a suitable map for further investigations connected with the study of the fine structure and the function of the CaMV genome.

Biophys J, 1979 Oct, 28(1), 65 - 79
Deoxythymidine sugars are not direct precursors of DNA-thymine; Loehr J et al.; A theoretical model for the kinetics of uptake of a putative precursor molecule into nucleotide pools and into replicating DNA has been developed . The relationship between the accumulation of radioactively labeled precursors in the pool and the appearance of radioactivity in DNA is then derived . Experiments have been carried out in bacteria to compare the uptake of radioactive thymine into deoxythymidine triphosphate, deoxythymidine diphosphate sugars, and DNA to test the suitability of either compound as the direct precursor of thymine in DNA . New one-dimensional, thin-layer chromatographic procedures were used to determine the specific activity of deoxythymidine triphosphate and deoxythymidine triphosphate and deoxythymidine diphosphate sugars in growing cultures of 32PO4-labeled Escherichia coli during pulse labeling with {3H}-thymine . A comparison of the experimental data with our theoretical model supports the hypothesis that deoxythymidine triphosphate, but not deoxythymidine sugar, is the direct precursor of thymine in normally replicating DNA in vivo.

J Biochem Biophys Methods, 1979 Oct, 1(5), 263 - 73
Chromatographic fractionation of Escherichia coli transfer RNA on a new support, naphthoyl-Sepharose; Hjerten S et al.; The noncharged naphthoyl-Sepharose CL-6B has been prepared . Escherichia coli tRNA binds to this new adsorbent in 0.75 M ammonium sulphate at neutral pH at room temperature . Using a negative salt gradient, the tRNAs are eluted in a defined order . The chromatographic pattern is clearly different from those of other commonly used tRNA separation techniques.

Arq Gastroenterol, 1979 Oct-Dec, 16(4), 205 - 8
An Escherichia coli strain that causes diarrhea by invasion of the small intestinal mucosa and induces monosaccharide intolerance; Fagundes Neto U et al.; E . coli can induced diarrhea either by enterotoxin production or by invasion of the colonic mucosa . Here we report a 2/12 year old infant with caute diarrhea induced by E . coli strain, isolated from the jejunal fluid, that had no enterotoxigenic activity but invaded the small intestinal mucosa and induced severe morphological alterations . Total villous atrophy and monosaccharide intolerance occured . After 51 days of hospitalization there was a partial recovery of the small intestinal morphology and the patient could also tolerate disaccharides again.

Int J Radiat Biol Relat Stud Phys Chem Med, 1979 Oct, 36(4), 349 - 57
Excision of uracil from bromodeoxyuridine-substituted and U.V.-irradiated DNA in cultured mouse lymphoma cells; Makino F et al.; A uracil-DNA glycosylase activity was detected in cell-free extracts from cultured mouse lymphoma L5178 cells . We investigated whether or not this enzyme plays a role in the removal of uracil from chromosomal DNA . U.V . light (254nm) irradiation of the cells with BUdR-substituted DNA produced not only single-strand breaks but also 'internal' uracil residues that were recognized as substrate sites by uracil-DNA glycosylase . These 'internal' uracil residues were lost from the DNA upon reincubation of the irradiated cells . The product released from the DNA was identified as uracil . Thus, the intracellular action of the uracil-DNA glycosylase was demonstrated and the subsequent reconstitution of the DNA strand was inferred in cultured mammalian cells.

J Gen Microbiol, 1979 Oct, 114(2), 467 - 70
Recombinant plasmids formed in vivo carrying and expressing two incompatibility regions; Nugent ME et al.; The formation in vivo of recombinants between a plasmid of incompatibility group N (R1010-10) and plasmids of groups P (R751) and W (R388) is described . From examination of the molecular weights of these recombinant plasmids, they appear to be cointegrates . These cointegrates have the incompatibility properties of both 'parent' plasmids.

Acta Haematol Pol, 1979 Oct, 10(4), 311 - 3
{Pericecal abscess and infiltration as a complication in the early phase of acute non-differentiated cell leukemia}; Sadowski J et al.; Acute abdomen syndrome was the presenting sign of leukaemia in the reported case . The authors discuss indications to surgical treatment in patients with leukaemia.

Genetics, 1979 Oct, 93(2), 353 - 60
Rho and ribosome mutation interaction: lethality of rho-15 in rpsL or rpsE strains, and rho-15 methionine auxotrophy in rps+ strains of Escherichia coli; Guterman SK et al.; The phenotype of Escherichia coli K-12 carrying rho-15 in the genetic background DW319 ilv lacZ::IS1 is described . Seventy-eight percent (70/90) of Ilv+ transductants acquired the following phenotype: temperature-sensitive growth on minimal salts medium, Ts+ growth on complex medium and suppression of the lac polar mutation . At 42 degrees on minimal medium, the rho-15 transductants were cross-fed by a substance diffusing from Rho+ transductants or controls . The requirement for this substance was satisfied by methionine or cystathionine, but not by any other single amino acid or combination of amino acids, by spermidine, or by mono- or divalent cationic salts.--Transduction of rho-15 into four other Ilv- recipients revealed two phenotypic patterns . Recipients with rpsL or rpsE ribosomes yielded rho-15 transductants that were Ts on all media, or Ts on minimal medium whether or not methionine was present . The effect of the ribosome on expression of rho-15 was confirmed by transduction of appropriate rps alleles into DW319, followed by co-transduction of rho-15 with Ilv+ . The growth rate of double rho-15 rpsL or rho-15 rpsE strains was severely reduced at 42 degrees in comparison with strains carrying any of these single mutations . Models for rho and ribosome interaction are presented.

Genetics, 1979 Oct, 93(2), 345 - 51
Suppression of the formation of polygenotypic recombinant colonies by a maf mutation in mating with HfrH; Ou JT et al.; W3011, a Cavalli-type Hfr (HfrC), was mated with F-KY9474, maf-1, which cannot maintain F or F-like plasmids, and with F-OU9474, Maf+, a spontaneous revertant of KY9474 . The recombinant colonies obtained were 100% monogenotypic from KY9474 and 90% monogenotypic from OU9474 . On the other hand, in matings with OU11, a Hayes-type Hfr (HfrH), and these two F- strains, recombinant colonies derived from KY9474 showed only 22% polygenotypic recombinant colonies; whereas, those derived from OU9474 showed a high production rate (57%) of polygenotypic recombinant colonies . Among the polygenotypic recombinant colonies derived from KY9474 maf-1, 50% contained three or more recombinant types . These were probably derived from a small fraction of Maf+ revertants in the KY9474 population, as suggested by the results of mating this strain with M80, an F' strain that contains an amber mutation in traH . These results support the hypothesis that the donor DNA fragments derived from an HfrH can undergo a limited replication in the recipient to produce polygenotypic recombinant colonies, whereas those derived from HfrC cannot.

Genetics, 1979 Oct, 93(2), 321 - 43
Deletions generated by the transposon Tn10 in the srl recA region of the Escherichia coli K-12 chromosome; Csonka LN et al.; A negative regulatory gene for the srl operon (srlR) was recognized by the characteristics of an insertion mutation generated by the transposon Tn10 determining tetracycline resistance . This finding is discussed in light of previous hypotheses on the regulation of the srl genes, which mediate metabolism of glucitol (i.e., sorbitol) . Mapping showed that the order of genes in this region is: srlR srlD srlC recA alaS . Using two different methods, five mutations of both srl and recA were detected . The phenotype conferred by these mutations, UV sensitivity and extreme recombination deficiency, is characteristic of standard recA point mutants . Three of the mutations were deletions that also removed the genes for tetracycline resistance of the nearby transposon . A fourth mutation ended at a distance from Tn10 sufficient to allow separation of the two by recombination following P1 transduction; our tests did not allow us to conclude whether this mutation was an inversion or a deletion . The fifth mutation was a deletion that seemed to end immediately adjacent to the boundary of Tn10, proximal to recA . Mechanisms for the generation of these srl recA mutations are discussed.

Genetics, 1979 Oct, 93(2), 308 - 19
Physiological characterization of polar Tn5-induced isoleucine-valine auxotrophs in Escherichia coli K.12: evidence for an internal promoter in the ilvOGEDA operon; Berg CM et al.; The properties of 22 isoleucine-valine auxotrophs induced in Escherichia coli K-12 by the transposable element, Tn5, were characterized on the basis of growth requirements, cross-feeding behavior, and enzyme activity . Mutants defective in ilvA, ilvC, ilvD and ilvE were found . Mutation in ilvE were not completely polar on ilvD and ilvA enzyme activities (that is, ilvE mutants possessed a low constitutive level of expression of the enzymes coded by ilvD and ilvA), while mutations in ilvD were completely polar on ilvA enzyme activity . The data suggest that there is an internal promoter between the sites of Tn5 insertion in ilvE and ilvD.

Can J Microbiol, 1979 Oct, 25(10), 1206 - 8
Regulation of peptidoglycan biosynthesis in relA+ and relA- strains of Escherichia coli during diauxic growth on glucose and lactose; Ishiguro EE; In both relA+ and relA- derivatives, the biosynthesis of peptidoglycan, lipid intermediates, and nucleotide precursors abruptly halted at the onset of diauxic lag from glucose to lactose with a concomitant accumulation of guanosine 5'-diphosphate 3'-diphosphate (ppGpp) . These results are consistent with the proposal that ppGpp is involved in inhibiting the incorporation of disaccharide-pentapeptide into peptidoglycan and in regulating nucleotide precursor synthesis.

Biochem J, 1979 Oct 1, 183(1), 11 - 22
Purification of the membrane-bound hydrogenase of Escherichia coli; Adams MW et al.; The membrane-bound hydrogenase (EC class 1.12) of aerobically grown Escherichia coli cells was solubilized by treatment with deoxycholate and pancreatin . The enzyme was further purified to electrophoretic homogeneity by chromoatographic methods, including hydrophobic-interaction chromatography, with a yield of 10% as judged by activity and an overall purification of 2140-fold . The hydrogenase was a dimer of identical subunits with a mol.wt . of 113,000 and contained 12 iron and 12 acid-labile sulphur atoms per molecule . The epsilon 400 was 49,000M-1 . cm-1 . The hydrogenase catalysed both H2 evolution and H2 uptake with a variety of artificial electron carriers, but would not interact with flavodoxin, ferredoxin or nicotinamide and flavin nucleotides . We were unable to identify any physiological electron carrier for the hydrogenase . With Methyl Viologen as the electron carrier, the pH optimum for H2 evolution and H2 uptake was 6.5 and 8.5 respectively . The enzyme was stable for long periods at neutral pH, low temperatures and under anaerobic conditions . The half-life of the hydrogenase under air at room temperature was about 12 h, but it could be stabilized by Methyl Viologen and Benzyl Viologen, both of which are electron carriers for the enzyme, and by bovine serum albumin . The hydrogenase was strongly inhibited by carbon monoxide (Ki = 1870Pa), heavy-metal salts and high concentrations of buffers, but was resistant to inhibition by thiol-blocking and metal-complexing reagents . These aerobically grown E . coli cells lacked formate hydrogenlyase activity and cytochrome c552.

Am J Vet Res, 1979 Oct, 40(10), 1391 - 7
Enterotoxigenic colibacillosis in colostrum-fed calves: pathologic changes; Bellamy JE et al.; Enterotoxigenic colibacillosis was experimentally produced in 8 of 9 colostrum-fed calves orally given 10(11) Escherichia coli . The eight calves developed profuse diarrhea accompanied by dehydration and depression . At 12 hours after exposure, all calves were euthanatized for necropsy and for collection of tissues for microscopic examination . Histopathologic changes included stunted villi in the jejunum and ileum, focal degeneration and exfoliation of absorptive epithelial cells at the tips of jejunal and ileal villi, and focal emigration of neutrophils which was especially prominent above the dome area of aggregated lymphatic follicles (Peyer's patches) . A layer of E coli adhered to the epithelial surface of the jejunum and ileum . In the duodenum, lesions were minimal or absent and bacteria were not adhering to the mucosa . Histopathologic changes were not observed in other tissues . In two calves examined 24 hours after they were inoculated and in two calves euthanatized 24 to 36 hours after spontaneously developing enteric colibacillosis, lesions were similar to those observed in the calves at 12 hours after exposure.

Acta Hepatogastroenterol (Stuttg), 1979 Oct, 26(5), 368 - 74
Binding sites for endotoxic lipopolysaccharide on the plasma membrane of isolated rabbit hepatocytes; Ramadori G et al.; The in vitro fixation of bacterial lipopolysaccharide (LPS) on the plasma membrane of mechanically or enzymatically isolated hepatocytes from rabbits was studied by immunofluorescence technique . Antisera against LPS from E . coli 026:B6 and 0111:B4 were induced in rabbits . Antibody titers up to 1:1024 were determined by the passive hemagglutination test . There was no immunologic cross reactivity between the two antisera . IgG and IgM were prepared from anti-LPS as well as from normal rabbit serum and conjugated with fluorescein-isothiocyanate . The antibody activity against LPS was localized in the IgM fraction . Hepatocytes were isolated by a perfusion technique without enzymes and with collagenase . LPS binding to the hepatocellular plasma membrane increased proportionally with the LPS concentration in a range between 0.01 and 1.0 mg per ml . The fluorescence pattern of the membrane fixed IgM anti-LPS-antibody at the surface of LPS coated hepatocytes was coarse granular . The in vitro reaction of LPS with hepatocytes was not influenced by the presence of complement . The demonstration of binding sites for LPS on the hepatocellular plasma membrane supports the hypothesis that not only Kupffer cells but also parenchymal liver cells are involved in the hepatic clearance activity for endotoxin.

Mol Gen Genet, 1979 Oct 1, 175(3), 369 - 73
IS4 is found between eleven or twelve base pair duplications; Habermann P et al.; Three mutations caused by the integration of IS4 in galT in both possible orientations were shown by DNA sequence analysis to be integrated between a duplication of eleven base pairs of gene galT . IS4 has been cloned from its single position on the E . coli K12 chromosome . Here, 12 base pairs are duplicated adjacent to IS4 . This sequence is unrelated to the duplicated sequence in galT.

Mol Gen Genet, 1979 Oct 1, 175(3), 343 - 50
Plasmid cistrons controlling synthesis and excretion of the exotoxin alpha-haemolysin of Escherichia coli; Noegel A et al.; The synthesis and secretion of the toxic exoprotein alpha-haemolysin of E . coli PM152 is coded by the transmissible plasmid pHly152 (41 x 10(6) dalton) as shown by the transformation of the plasmid DNA and the isolation of mutants that are specifically altered in the synthesis and transport of haemolysin . These mutants were obtained by chemical mutagenesis and insertion of the ampicillin transposon (Tn3) into pHly152 . Tn3 transposition was also used for the identification and the location of the cistrons on pHly152 essential for haemolysis . The EcoRI and HindIII fragments of the haemolytic plasmid pHly152 were cloned and used for the complementation of the haemolysis negative Tn3 insertion mutants . A DNA segment of 3.2 x 10(6) dalton could be thus identified which consists of at least three clustered cistrons necessary for haemolysis . Two of these cistrons are required for the formation of active haemolysin . At least one other cistron seems to be involved in the secretion of active haemolysin through the outer membrane of E . coli . The gene products determined by these cistrons were identified in minicells of E . coli . Their molecular properties were determined and their possible function in the formation and secretion of haemolysin will be discussed.

Mol Gen Genet, 1979 Oct 1, 175(3), 305 - 11
Natural premature protein synthesis termination can be reduced in Escherichia coli by decreased translation rates; Atherly AG; Peptidyl tRNA hydrolase is an essential enzyme for normal growth inasmuch as a mutant strain of Escherichia coli with a temperature-sensitive hydrolase cannot continue protein synthesis at the non-permissive temperature . In the absence of hydrolase peptidyl tRNA rapidly accumulates . Why peptidyl tRNA should be formed is the subject of this report . The rapid rate of protein synthesis is likely one mechanism of formation of peptidyl tRNA . A strA mutant of the hydrolase (pth-1) mutant strain that has a 40% reduction in amino acid polymerization rate can grow at 42 degrees C . StrA mutants with normal polymerization rates, however, cannot grow at 42 degrees C when pth-1 is present . Furthermore, addition of low levels of chloramphenicol (2--4 micrograms/ml) but not several other tested drugs, phenotypically suppressed pth-1 at 42 degrees C . Chloramphenicol, at these concentrations, was found to reduce the amino acid polymerization rate 30--40% . On the other hand, no evidence could be found that amino acyl tRNA selection errors are incorporated into pseudo revertants of the pth-1 strain.

Mol Gen Genet, 1979 Oct 1, 175(3), 275 - 9
A novel priming system for conjugal synthesis of an IncI alpha plasmid in recipients; Boulnois GJ et al.; Synthesis of DNA complementary to the transferred strand of an IncI alpha plasmid has been shown previously to require DNA polymerase III . The possible involvement of the two defined priming proteins of Escherichia coli K12, RNA polymerase and primase, in initiating this conjugal DNA synthesis had been examined . Primase was inactivated using temperature-sensitive dnaG3 mutants and RNA polymerase was inhibited using rifampicin . When these two proteins were simultaneously inactivated in both parental strains, the average recipient synthesised at least one single-stranded equivalent of R144drd-3 before the rifampicin-treated donors lost the ability to transmit DNA . It is proposed that the product of a plasmid transfer gene is responsible for initiating this DNA synthesis in recipients . The results imply that this protein is supplied by the donors.

Gann, 1979 Oct, 70(5), 705 - 8
Effect of N-carboxymethyl-N-nitrosourea on viability and mutagenic response of repair-deficient strains of Escherichia coli; Yoshikawa K et al.; Under simulated human gastric conditions, glycocyamine which exists in meat is known to be converted into N-carboxymethyl-N-nitrosourea (CMNU) by reaction with sodium nitrite . Because of its suspected hazards to man, CMNU was tested for its mutagenicity and lethal activity with a set of isogenic strains of Escherichia coli possessing the same auxotrophic marker but different DNA-repair capacities . Both strains NG30 (recA-) and R15 (polA-) were far more sensitive to lethality induced by CMNU than H/r30R (wild) and Hs30R (uvrA-) strains . The uvrA- strain was more sensitive to induction of mutations by CMNU than the wild and polA- strains, but the recA- strain was hardly mutable by CMNU . It can be concluded from these findings that the major cause of lethality of CMNU in E . coli is different from that of mutation induction.

Res Commun Chem Pathol Pharmacol, 1979 Oct, 26(1), 187 - 96
Steric hindrance enzyme immunoassay (SHEIA); a novel method in enzyme immunoassay; Monji N et al.; We have developed a new method for separation of antibody bound and unbound enzyme conjugates . The technique as applied to the assay of choriomammotropin involves the use of beta-D-galactosylamine bound to agarose to separate the unbound choriomammotropin-beta-galactosidase conjugates for antibody bound conjugates . When beta-galactosidase was conjugated with choriomammotropin using the N-hydroxy-succinamide ester of m-maleimidobenzoic acid the affinity of the enzyme conjugate to beta-D-galactosylamine attached to agarose diminished markedly following incubation with antibody . In a typical enzyme immunoassay of choriomammotropin, 5 microliter of swelled affinity gel per tube was required to precipitate unbound enzyme following one hour gentle shaking at room temperature . Choriomammotropin antibody was used at titer of 1:1,000 . The standard curve for the assay was adjusted to cover a range of 0-10 mg/l with maximum sensitivity between 1-4 mg/l.

Mutat Res, 1979 Oct, 62(3), 451 - 7
UV protection and mutagenesis in uvrD, uvrE and recL strains of Escherichia coli carrying the pKM101 plasmid; Todd PA et al.; The effect of the pKM101 plasmid on UV mutagenesis and survival was examined in DNA-repair-deficient strains of E . coli carrying the uvrD, uvrE and recL mutations . Although enhancement of UV mutagenesis by pKM101 was found in all 3 strains, UV protection was only observed in the uvrD strain . We conclude that the plasmid not only requires lexA+ recA+ functions of the cell, but also those of uvrE+ recL+ for its UV-protective effect.

J Med Chem, 1979 Oct, 22(10), 1260 - 3
In vivo inhibitors of Escherichia coli phenylalanyl-tRNA synthetase; Santi DV et al.; N-Benzyl-D-amphetamine is a potent in vitro and in vivo inhibitor of phenylalanyl-tRNA synthetase of Escherichia coli . The concentration of this inhibitor necessary for the in vivo inhibition is approximately 100-fold greater than that necessary for inhibition of the purified enzyme . Treatment of rel+ strains of E . coli with the inhibitor results in a decreased percentage of tRNA Phe which is charged, guanosine tetraphosphate formation, cessation of RNA synthesis, and growth arrest . Evidence is presented which demonstrates that the primary and perhaps sole mode of action of N-benzyl-D-amphetamine is inhibition of phenylalanyl-tRNA synthetase.

J Infect Dis, 1979 Oct, 140(4), 626 - 8
Evidence for enterotoxin production by a classic enteropathogenic serotype of Escherichia coli; Ryder RW et al.; Isolates of classic enteropathogenic Escherichia coli O:128 that had been implicated in an outbreak of diarrhea in a hospital nursery were found to produce heat-stable enterotoxin after storage for six years . This finding indicated that enteropathogenicity and the ability to produce enterotoxin may coincide in E . coli, and further study of enteropathogenic strains that produce enterotoxin may help in elucidation of the relationship between enteropathogenic and enterotoxigenic E . coli.

Am J Ophthalmol, 1979 Oct, 88(4), 708 - 13
Pneumatosis oculi and spontaneous hyphema in association with pneumatosis intestinalis; Lissner GS et al.; A premature infant with acute necrotizing enterocolitis, Escherichia coli sepsis, and disseminated intravascular coagulation developed spontaneous bilateral hyphemas at 3 days of age . The necrotizing enterocolitis was associated with gas bubbles in the intestinal walls . The anterior chambers of both eyes also contained bubbles of gas, formed possibly by a mechanism similar to those in the intestine.

Proc Natl Acad Sci U S A, 1979 Oct, 76(10), 5105 - 9
A 3.0-A resolution study of nucleotide complexes with aspartate carbamoyltransferase; Honzatko RB et al.; The binding sites of CTP, CDP, 5-BrCTP, and ATP to the allosteric site of aspartate carbamoyltransferase (carbamoylphosphate:L-aspartate carbamoyltransferase, EC 2.1.3.2) have been found in electron-density maps obtained at about 3 A resolution from x-ray diffraction studies of single crystals . The activator ATP binds in the anti conformation, whereas the inhibitor 5-BrCTP binds in the syn conformation . Both activator and inhibitor bind to the same local region of the enzyme . All of the cytidine nucleotides show important interactions of the base with the protein . The triphosphate conformations are similar, whereas the terminal phosphate of CDP occupies the site of the gamma-phosphate of CTP, thus implying a protein-nucleotide interaction at this site . These results are then related to biochemical studies.

Proc Natl Acad Sci U S A, 1979 Oct, 76(10), 5095 - 9
RNA polymerase III transcriptional units are interspersed among human non-alpha-globin genes; Duncan C et al.; Cloned human DNA fragments containing globin genes are transcribed in vitro to form discrete RNA species . One transcription unit is located approximately 1500 base pairs upstream from the G-gamma-globin gene . This transcript is partially homologous to a polymerase III template located approximately 1000 base pairs upstream from the delta-globin gene and to DNA located a short distance downstream from the beta-globin gene.

Proc Natl Acad Sci U S A, 1979 Oct, 76(10), 5036 - 40
Construction and selection of recombinant plasmids containing full-length complementary DNAs corresponding to rat insulins I and II; Chan SJ et al.; We have used a synthetic deoxydecanucleotide to generate an insulin-specific cDNA probe suitable for selecting transformants that contain nearly full-length cDNAs corresponding to the mRNAs coding for rat insulins I and II . Double-stranded cDNA was synthesized from x-ray-induced rat insulinoma poly(A)-RNA, inserted in pBR322 plasmid DNA by the homopolymeric tailing technique, and cloned in Escherichia coli chi 1776 . Colony hybridization with oligonucleotide-primed cDNA yielded 16 positive clones of which 7 corresponded to rat insulin I mRNA and 9 to rat insulin II mRNA . Restriction endonuclease maps of representative clones of each group indicated that these contained the complete coding sequences, as was confirmed by nucleotide sequence analysis of the 5' region of the cloned DNA for rat insulin II . Nucleotide sequence analysis also established the amino acid sequence of the prepeptide of rat preproinsulin II . Comparison of the amino acid sequence of the prepeptides of rat preproinsulin I and II shows that three conservative amino acid substitutions have occurred in this region of the molecule.

Proc Natl Acad Sci U S A, 1979 Oct, 76(10), 5014 - 7
Primary structure of major outer membrane protein I of Escherichia coli B/r; Chen R et al.; The amino acid sequence of the pore-forming outer membrane protein I (porin) from Escherichia coli B/r has been determined . The polypeptide contains 340 amino acid residues resulting in a molecular weight of 37,205 . The transmembrane polypeptide has no stretches of nonpolar residues, uninterrupted by charged side chains, longer than 11 amino acid residues . Regarding polarity, the chain can be subdivided into three regions: a distinctly hydrophilic region between residues 1 and 82 (51.2% polarity), a fairly nonpolar region between residues 83 and 194 (33.9% polarity), and a more hydrophilic region up to the COOH terminus (48% polarity) . These results are interpreted as evidence against a simple transmembrane structure in which the membrane is spanned by a single contiguous sequence of hydrophobic amino acids, as has been proposed, for example, for glycophorin.

Proc Natl Acad Sci U S A, 1979 Oct, 76(10), 4981 - 5
Cloning and nucleotide sequence of DNA coding for bovine preproparathyroid hormone; Kronenberg HM et al.; We have cloned in Escherichia coli a DNA copy of mRNA coding for bovine preproparathyroid hormone . Double-stranded DNA was inserted into the Pst I site in plasmid pBR322 by using the poly(dG)-poly(dC) homopolymer extension technique to join the DNA molecules . Recombinant plasmids coding for preproparathyroid hormone were identified by the plasmid's ability to arrest specifically the translation of preproparathyroid hormone mRNA . The nucleotide sequence of the largest recombinant was determined by using both chemical and enzymatic techniques . The parathyroid insert contains 470 nucleotides--102 nucleotides from the 5' noncoding region of the mRNA, 345 nucleotides representing the entire coding region, and 23 nucleotides from the 3' noncoding region . The coding sequence clarifies the hormone's amino acid sequence, which has been disputed . Codon usage is discussed.

Proc Natl Acad Sci U S A, 1979 Oct, 76(10), 4867 - 71
Quaternary structure of the ribosomal 30S subunit: model and its experimental testing; Spirin AS et al.; In considering the structure of the 30S subunit of the Escherichia coli ribosome, we have assumed that: (i) all or almost all the proteins within the 30S particle are compact and globular, as recently shown for the isolated proteins S4, S7, S8, S15, and S16 in solution {Serdyuk, I.N., Zaccai, G . & Spirin, A.S . (1978) FEBS Lett . 94, 349-352}; (ii) the RNA within the 30S particle has approximately the same specific V-like or Y-like shape that was demonstrated for the isolated 16S RNA in a compact conformation {Vasiliev, V.D., Selivanova, O.M . & Koteliansky, V.E . (1978) FEBS Lett . 95, 273-276} . From these assumptions and using the numerous data reported on neighboring ribosomal proteins, we have constructed a model of the quaternary structure of the ribosomal 30S subunit . The model has been tested by calculation of the theoretical curves of neutron scattering at different contrasts, as well as those of x-ray scattering, and their comparison with the experimental scattering curves for E . coli 30S particles . It has been found that the calculated scattering curves for the model practically coincide with the experimental scattering curves for the 30S particles in the range of Bragg distances down to 40-55 A . The scattering curves calculated for several three-dimensional patterns of arrangement of the 30S subunit proteins proposed earlier have been shown to be inconsistent with the experiments.

J Biochem (Tokyo), 1979 Oct, 86(4), 1129 - 38
Properties of purified detergent-resistant phospholipase A of Escherichia coli K-12 . Inactivation, and protection with detergents and phospholipids; Tamori Y et al.; A crude preparation of membrane-bound phospholipase A (detergent-resistant) in Escherichia coli K-12 cells was found to be quite stable or even apparently activated on incubation at 100 degrees C, but became strikingly thermolabile when it was highly purified and Triton X-100 was removed from the purified enzyme preparation . The rate of inactivation showed a biphasic temperature dependence: inactivation was rapid at 37 degrees C and also above 70 degrees C . Inactivation above 70 degrees C changed the mobility of the enzyme on sodium dodecyl sulfate/polyacrylamide gel electrophoresis, but inactivation at 37 degrees C did not affect the electrophoretic mobility . Triton X-100 effectively protected the enzyme against inactivation at 37 degrees C . The concentration required for the protection of the enzyme was more than its critical micelle concentration . Phospholipids, such as phosphatidylethanolamine, phosphatidylglycerol, cardiolipin, phosphatidylcholine, lysophosphatidylethanolamine, and lysophosphatidylcholine, also protected the enzyme against inactivation at 37 degrees C . These results suggest that the binding of hydrophobic compounds stabilizes the enzyme.

J Bacteriol, 1979 Oct, 140(1), 301 - 5
Deletions in the r-determinant mer region of plasmid R100-1 selected for loss of mercury hypersensitivy; Foster TJ et al.; A mutant of plasmid R100-1, which conferred cellular hypersensitivity to Hg2+ because of the insertion of Tn801 (TnA) into the gene determining synthesis of mercuric reductase enzyme, allowed further mutational events to be selected which resulted in either reversion to Hg2+ resistance (characteristic plasmid R100-1) or sensitivity at a level characteristic of plasmidless strains . Restriction endonuclease EcoRI and BamHI analysis showed that reversion to resistance resulted from loss of TnA from the R100-mer:Tn801 plasmid, whereas the change from hypersensitivity to sensitivity to Hg2+ usually resulted from deletion of part or all of Tn801 plus plasmid deoxyribonucleic acid sequences corresponding to the operator-proximal end of the mer operon.

J Bacteriol, 1979 Oct, 140(1), 229 - 39
Escherichia coli pleiotropic mutant that reduces amounts of several periplasmic and outer membrane proteins; Wanner BL et al.; We have isolated a mutant of Escherichia coli K-12 that is reduced from 6- to 10-fold in the amount of alkaline phosphatase found in the periplasmic space . The reduced synthesis is not due to effects at the level of transcription regulation of the phoA gene, the structural gene for the enzyme . In addition, the mutation (termed perA) responsible for this phenotype results in reduced amounts of possibly six or more other periplasmic proteins and at least three outer membrane proteins . One of the outer membrane proteins affected is protein IA (D . L . Diedrich, A . O . Summers, and C . A . Schnaitman, J . Bacteriol . 131:598-607, 1977) . Although other possibilities exist, one explanation for the phenotype of the perA mutation is that it affects the cell's secretory apparatus.

J Bacteriol, 1979 Oct, 140(1), 167 - 81
Transposon A-generated mutations in the mercuric resistance genes of plasmid R100-1; Foster TJ et al.; A series of 23 transposon 801(Tn801)-induced mutations of plasmid R100-1 from mercuric salts resistance to sensitivity was studied . Although Tn801 transposed frequently into the mer region of the plasmid, fine structural analysis showed that the site of insertion within mer varied . About one-half of the Tn801 insertion events also caused a deletion of greater than 1 megadalton . Genetic and restriction endonuclease EcoRI and BamHI analysis of the mutant plasmid deoxyribonucleic acid elucidated the organization of the mer operon and suggested the existence of a trans-acting regulatory factor governing resistance to mercuric salts . Tn801 insertions leading to mercuric sensitivity occurred in the restriction endonuclease fragments EcoRI-H and EcoRI-I . Regulatory mutations leading to a 50-fold-reduced synthesis of mercuric reductase enzyme occurred in two complementation classes thought to represent the gene for a trans-acting inducer molecule and a cis-acting operator-promoter sequence . Mutations leading to total loss of the enzyme mercuric reductase occurred on both the EcoRI-H and EcoRI-I fragments, showing that the structural gene for this enzyme (merA) bridges the EcoRI cleavage site separating the segments . Hypersensitivity to mercuric salts resulted when Tn801 insertion occurred in the reductase gene in the operatordistal portion of the operon . Hypersensitive cells inducibly bound three to five times more Hg2+ at low concentrations than did sensitive (plasmidless) cells . This finding led to the proposal that another gene (merT) controls uptake of Hg2+ by the cells . Transcription of the operon was deduced to start in the EcoRI-H fragment and to move into the EcoRI-I fragment of the plasmid genome.

J Bacteriol, 1979 Oct, 140(1), 161 - 6
Hypersensitivity to Hg2+ and hyperbinding activity associated with cloned fragments of the mercurial resistance operon of plasmid NR1; Nakahara H et al.; The region of plasmid NR1 concerned with resistance to Hg2+ and organomercurials consists of sequences found on restriction endonuclease fragments EcoRI-H and EcoRI-I . When both fragments were cloned together into a derivative of plasmid ColE1, the hybrid plasmid conferred properties indistinguishable from those of the parental plasmid, NR1: resistance to Hg2+ and to the organomercurials merbromin and fluoresceinmercuric acetate and the inducible synthesis of the enzyme mercuric reductase . When fragment EcoRI-I was cloned into plasmid ColE1, cells containing the plasmid was as sensitive to Hg2+ and organomercurials as plasmidless strains . When fragment EcoRI-H was cloned into ColE1, cells with the hybrid plasmid were hypersensitive to Hg2+ and organomercurials . This hypersensitivity was inducible by prior exposure to low, subtoxic Hg2+ or merbromin levels . It was associated with an inducible hyperbinding activity attributed to a gene governing Hg2+ uptake and found on fragment EcoRI-H (which contains the proximal portion of a mercuric resistance {mer} operon).

J Bacteriol, 1979 Oct, 140(1), 125 - 30
Isolation and characterization of mutations in the structural gene for protease III (ptr); Cheng YS et al.; Escherichia coli mutants defective in protease III were isolated by enzyme assays of heavily mutagenized colones . One mutant produced thermolabile enzyme, and it is presumed to have a mutation in the structural gene of protease III . Two other mutants mapping at the same site had less than 5% of the wild-type protease III level . The genetic locus of these mutations, designated ptr, was located at approximately 60 min on the E . coli linkage map based on its high frequency (70%) of contransduction by P1 with argA . Strains with less than 5% of the wild-type protease III activity grew normally and degraded nonsense fragments of beta-galactosidase at wild-type rates.

J Bacteriol, 1979 Oct, 140(1), 114 - 24
Characterization of molybdenum cofactor from Escherichia coli; Amy NK et al.; Molybdenum cofactor activity was found in the soluble fraction of cell-free extracts of Escherichia coli grown aerobically in media supplemented with molybdate . Cofactor was detected by its ability to complement the nitrate reductase-deficient mutant of Neurospora crossa, nit-1, resulting in the vitro formation of nitrate reductase activity . Acid treatment of E . coli extracts was not required for release of cofactor activity . Cofactor was able to diffuse through a membrane of nominal 2,000-molecular-weight cutoff and was insensitive to trypsin . The cofactor was associated with a carrier molecule (approximately 40,000 daltons) during gel filtration and sucrose gradient centrifugation, but was easily removed from the carrier by dialysis . The carrier molecule protected the cofactor from inactivation by heat or oxygen . E . coli grown in molybdenum-free media, without and with tungsten, synthesized a metal-free "empty" cofactor and its tungsten analog, respectively, both of which were subsequently activated by the addition of molybdate . Empty and tungsten-containing cofactor complemented the nitrate reductase subunits in the nit-1 extract, forming inactive, but intact, 7.9S nitrate reductase . Addition of molybdate to the enzyme complemented in this manner restored nitrate reductase activity.

J Bacteriol, 1979 Oct, 140(1), 1 - 13
Escherichia coli mutants impaired in maltodextrin transport; Wandersman C et al.; Wild-type Escherichia coli K-12 was found to grow equally well on maltose and on maltodextrins containing up to seven glucose residues . Three classes of mutants unable to grow on maltodextrins, but still able to grow on maltose, were investigated in detail . The first class, already known, was composed of phage lambda-resistant mutants, which lack the outer membrane protein coded by gene lamB . These mutants grow on maltose and maltotriose but not at all on maltotetraose and longer maltodextrins which cannot cross the outer membrane . A second class of mutants were affected in malE, the structural gene of the periplasmic maltose binding protein . The maltose binding proteins isolated from the new mutants were altered in their substrate binding properties, but not in a way that could account for the mutant phenotypes . Rather, the results of growth experiments and transport studies suggest that these malE mutants are impaired in their ability to transport maltodextrins across the outer membrane . This implies that the maltose binding protein (in wild-type strains) cooperates with the lambda receptor in permeation through the outer membrane . The last class of mutants described in this paper were affected in malG, or perhaps in an as yet undetected gene close to malG . They were defective in the transfer of maltodextrins from the periplasmic space to the cytoplasm but only slightly affected in the transport of maltose.

Infect Immun, 1979 Oct, 26(1), 339 - 47
Relationship between the intestinal permeability to macromolecules and invasion of septicemia-inducing Escherichia coli in neonatal piglets; Murata H et al.; The influence of age and diet on the invasion of septicemia-inducing Escherichia coli and the endocytotic activity of the small intestinal epithelium were examined in colostrum-deprived conventional and gnotobiotic piglets orally infected with E . coli 078 . The piglets infected at birth and the animals fed glucose-amino acids solution and infected at 3 days after birth soon suffered from septicemia caused by the invasion of E . coli 378 . The piglets fed artifical milk and infected at 3 days after birth, however, showed resistance to the invasion of E . coli in the absence of passively acquired serum gamma globulin . The endocytotic activity of the small intestinal epithelium was more intense in the former than in the latter piglets . Some of the ileal epithelial cells of the piglets infected at birth contained organisms, although these cells were morphologically intact and showed intense endocytosis . The present results suggest that the intestinal permeability to macromolecules, which depends on the endocytotic activity of the small intestinal epithelium, might predispose neonatal piglets to colisepticemia.

Infect Immun, 1979 Oct, 26(1), 173 - 7
Isolation and partial characterization of two different heat-stable enterotoxins produced by bovine and porcine strains of enterotoxigenic Escherichia coli; Kapitany RA et al.; Heat-stable enterotoxins (ST-124 and ST-1261) have been isolated from two different enterotoxigenic Escherichia coli of bovine (124) and porcine (1261) origin . The enterotoxin preparations were isolated by ultrafiltration and ion-exchange chromatography and were both active in the suckling mouse test and pig ligated loop test in the nanogram range . The bovine (ST-124) enterotoxin was not stable to heating in its isolated form, and significant differences in amino acid composition were observed between the two enterotoxins . Although both toxins were active at similar levels in the suckling mouse and pig ligated loop tests, ST-124 lacked the ability to cause the profound secretory responses seen with ST-1261 in the weanling pig ligated loop.

Hoppe Seylers Z Physiol Chem, 1979 Oct, 360(10), 1483 - 95
Amino acid sequences of the tryptic peptides from carboxymethylated L-asparaginase from Escherichia coli; Maita T et al.; S-Carboxymethylated L-asparaginase was digested with trypsin and the resulting peptides were isolated by using gel filtration, ion exchange column chromatography and paper chromatography . Among the peptides thus isolated, 27 peptides were considered not to overlap and the sum of the amino acids from these 27 peptides is in good agreement with amino acid composition of the enzyme . The amino acid sequences of the peptides were determined by fragmentation with various enzymes and subtractive Edman degradation.

Chem Biol Interact, 1979 Oct, 27(2-3), 221 - 33
Mutation induction and killing of Escherichia coli by DNA adducts and crosslinks: a photobiological study with 8-methoxypsoralen; Bridges BA et al.; Low doses of 350 nm radiation (NUV) in the presence of 8-methoxypsoralen (8-MOP) induce predominantly mono-adducts in bacterial DNA . Further exposure to NUV in the absence of 8-MOP converts a proportion of these mono-adducts to interstrand cross-links . Using this approach the relative effects of adducts and cross-links on bacteria with different repair capacities was studied . Escherichia coli WP100 uvrA recA, believed to be totally deficient in the ability to repair 8-MOP plus NUV damage to DNA, was inactivated on average by a single photon event occurring with a quantum efficiency of about 0.03 . We conclude that the inactivating lesion is probably a single mono-adduct . E . coli WP2 uvrA, deficient in excision endonuclease activity, may be inactivated by a very small number of cross-links, probably one . These conclusions are consistent with present knowledge of the repair capabilities of these bacteria . Conversion of mono-adducts to cross-links in WP2 uvrA (which occurs with a quantum efficiency of around 0.3) greatly increases lethality but results in a reduction of the induced mutation frequency presumably because cross-links are (almost) invariably lethal . In the repair-proficient strain WP2 both adducts and cross-links can be repaired but the latter are more likely than the former to lead to either death or mutation.

Cell, 1979 Oct, 18(2), 277 - 85
The molecular topography of RNA polymerase-promoter interaction; Simpson RB; Ultraviolet irradiation forms covalent crosslinks between E . coli RNA polymerase and the lac UV5 promoter substituted with bromouracil in the place of thymine . I have determined the polymerase subunit and the base within the promoter sequence that are joined to each other in two such crosslinks . The sigma and beta subunits of RNA polymerase, respectively, are crosslinked to the third base upstream (-3) and the second base downstream (+3) from the starting point of transcription (+1) . Both bases are on the nontemplate strand of the promoter DNA . The location of the beta subunit suggests that it forms at least part of the catalytic site of the enzyme . The disposition of sigma suggests that this subunit plays a direct role in unwinding the DNA at the promoter . The sigma crosslink is close to the "Pribnow Box," which is centered about 10 bases upstream from the RNA start site, contains a striking homology between promoters and is the locus of many promoter mutations.

Antibiotiki, 1979 Oct, 24(10), 761 - 4
{Conjugative properties of the R factors found in 2 different strains of Escherichia coli}; Bel'kind AM; The transfer frequency of R124-17, RI, RI-19 and RP4 factors as dependent on the origin of the donor strain was studied . The transfer frequencies of these factors from E . coli W strains are much lower than those from the strains of E . coli K12 . The effect is connected neither with the repression of the tra-genes, nor with the restriction enzymes activity against the alien DNA in the recipient bacteria.

J Hyg (Lond), 1979 Oct, 83(2), 243 - 54
Bacteriostasis of Escherichia coli by milk . III . The activity and stability of early, transitional and mature human milk collected locally; Honour P et al.; Milk from 150 local mothers has been assayed for bacteriostatic activity for milk-sensitive and milk-resistant indicator strains of Escherichia coli . Activity is greatest in colostrum which is active directly against all strains of E . coli . One week after delivery of the baby, milk is active against the milk-sensitive strain and becomes active against the milk-resistant strain in the presence of physiological amounts of bicarbonate and iron-binding protein . This activity decreases within 2--4 days on keeping milk unheated at 4 degrees C but is preserved for at least 4 months and often up to 2 years in milk heated to 56 degrees C then stored at 4 degrees C or in milk frozen, unheated, at -28 degrees C provided it is not repeatedly thawed and frozen . Later lactation milks are usually indistinguishable in activity from 1-week post-partum milk but may be less stable on storage particularly if frozen . Lyophyilization in vacuo preserves activity of early-lactation milk for at least 6 months . Heating milk to above 65 degrees C causes a progressive loss of activity which can be partially restored by adding bicarbonate and iron-binding protein . Iron abolishes the activity of milk and reduces that of colostrum.

Eur J Biochem, 1979 Oct, 100(1), 101 - 13
50-S subunit from Escherichia coli ribosomes . Isolation of active ribosomal proteins and protein complexes; Wystup G et al.; A method is described for the isolation of highly purified proteins from the 50-S subunit of Escherichia coli ribosomes . All the proteins from the large subunit could be isolated with the exception of L14, L26, L31 and L34 . The isolated proteins are functionally active in reconstituted particles . The method consists of successive NH4Cl/EtOH and LiCl washing steps, which split off distinct groups of proteins from the ribosome . The protein groups are further separated by a combination of gel filtration (Sephadex G-100) and ion-exchange chromatography (carboxymethylcellulose) in the presence of 6 M urea, at neutral pH and 4 degrees C . The purity of the proteins was analyzed by two-dimensional gel electrophoresis . In addition, ten protein complexes were isolated and identified.

Gene, 1979 Oct, 7(2), 153 - 71
In vivo enhancement of general and specific transcription in Escherichia coli by DNA gyrase activity; Kubo M et al.; The effect of drugs which inhibit DNA gyrase, including nalidixic acid, oxolinic acid and coumerycin, on transcription of Escherichia coli bacteria, phage and plasmid genomes was studied . Quantitative estimates of the synthesis of RNA under drug-treatment conditions showed that synthesis of many RNA species, including trp mRNA, was subject to inhibiton by the drug . Transcription directed by the lambda promoter pR was selectively less sensitive to the drug action than transcription initiated at the lambda promoter pL . Evidence was obtained showing that diminished transcription resulted from less frequent RNA chain initiation rather than a premature arrest of the chain elongation . Inhibiton of transcription by these DNA gyrase inhibitors was observed even in the absence of DNA replication . The inhibition by oxolinic acid or coumerycin was not observed in an E . coli strain bearing a nalAr mutation or a cour mutation, respectively . The reduction of trp mRNA synthesis in oxolinic acid-treated cells cannot be attributed to the increase in the rate of nascent mRNA degradation . These results indicate that DNA gyrase is generally required for intracellular RNA synthesis, and suggest that the supercoiling of DNA by this winding enzyme enhances the initiation of transcription.

Proc Natl Acad Sci U S A, 1979 Oct, 76(10), 5090 - 4
Interaction site of Escherichia coli cyclic AMP receptor protein on DNA of galactose operon promoters; Taniguchi T et al.; Cyclic AMP (cAMP) and its receptor protein (CRP) have a dual role in the regulation of the two promoters that control the galactose (gal) operon of Escherichia coli . One promoter, P1, requires cAMP-CRP for activity; the other, P2, is inhibited by these factors . We have examined the interactions site of cAMP-CRP on gal DNA by using two types of protection experiments, involving DNase digestion and methylation by dimethyl sulfate . Our results indicate that cAMP-CRP binds to gal DNA in a segment located between 50 and 24 base pairs preceding the P1 start point for transcription . Although the location of the cAMP-CRP interaction site is clearly different in gal and lac DNA, comparison of the DNA sequences suggests a similar recognition sequence . The location of the cAMP . CRP-binding site in gal further suggests that protein-protein interactions between RNA polymerase and cAMP . CRP play an important role in transcription initiation at the gal and possibly other cAMP-dependent promoters.

J Bacteriol, 1979 Oct, 140(1), 50 - 8
Deoxyribonucleic acid and outer membrane: strains diploid for the oriC region show elevated levels of deoxyribonucleic acid-binding protein and evidence for specific binding of the oriC region to outer membrane; Wolf-Watz H et al.; We have recently reported that part of the chromosomal deoxyribonucleic acid (DNA) of Escherichia coli is associated with the outer membrane fraction and that an outer membrane protein having a molecular weight of 31,000 probably is involved in this association (H . Wolf-Watz and A . Norqvist, J . Bacteriol . 140:43-49, 1979) . We have now found that F' merodiploid strains containing two copies of the DNA between bglB and ilv have increased levels of this protein and an increased amount of DNA in their outer membranes . Increased levels of the protein are also found when lambda asn phage, containing at 1.5-megadalton fragment of DNA located to the right of the uncA uncB genes but to the left of oriC, are induced . It therefore seems that this 1.5-megadalton fragment of DNA either codes for or binds to the 31,000-dalton outer membrane protein . Hybridization studies utilizing DNA found to be bound to outer membrane and DNA isolated from a specialized transducing phage lambda asn 132 revealed that at least 5 to 10% of outer membrane DNA has a DNA sequence homologous with a chromosomal segment carried by this oriC-containing phage.

J Bacteriol, 1979 Oct, 140(1), 43 - 9
Deoxyribonucleic acid and outer membrane: binding to outer membrane involves a specific protein; Wolf-Watz H et al.; The binding of deoxyribonucleic acid (DNA) to the outer membrane of Escherichia coli was examined . The amount of DNA found to be bound to outer membrane was low and was estimated to be about 0.4% of the total DNA . Treatment of cells with chloramphenicol or rifampin caused a disassociation of the apparent DNA-outer membrane complex . The results presented here suggest that the binding between membrane and DNA is specific and involves a membrane protein having a molecular weight of 13,000.

J Bacteriol, 1979 Oct, 140(1), 14 - 9
Mutant single-strand binding protein of Escherichia coli: genetic and physiological characterization; Glassberg J et al.; A mutation in the Escherichia coli gene for single-strand binding protein results in temperature-sensitive deoxyribonucleic acid replication (R . R . Meyer, J . Glassberg, and A . Kornberg, Proc . Natl . Acad . Sci . U.S.A . 76:1702-1705, 1979) . The mutant (ssb-1) is also more sensitive to ultraviolet irradiation and about one-fifth as active in recombination . Single-strand binding protein is thus implicated in repair and recombination as well as in replication . The mutation in ssb is located between uvrA and melA at 90.8 min on the genetic map . The ssb gene appears to be allelic with lexC, a gene with a proposed role in regulating inducible deoxyribonucleic acid repair.

Eur J Biochem, 1979 Oct, 100(1), 175 - 80
The ATP synthetase of Escherichia coli K12: purification of the enzyme and reconstitution of energy-transducing activities; Friedl P et al.; The ATP synthetase of Escherichia coli K12 was purified by a simple procedure . The dicyclohexylcarbodiimide-sensitive ATPase activity was enriched 21-fold . The ATP synthetase preparation contained the eight polypeptides (alpha, beta, gamma, a,delta, b,espilon, c) of the enzyme and a residual contamination (4% of the total protein) as shown by dodecylsulfate/polyacrylamide electrophoresis . The polypeptide c was specifically labelled with {14C}dicyclohexylcarbodiimide . Energy-transducing activities were reconstituted from soybean phospholipids and the purified enzyme . The proteoliposomes exhibited a significantly higher ATP-32Pi exchange activity and a higher proton-translocating activity as compared to the untreated membranes.

J Gen Microbiol, 1979 Oct, 114(2), 471 - 5
Complementation analysis of eleven tryptophanase mutations in Escherichia coli; White MK et al.; Nine independent mutants deficient in tryptophanase activity were isolated . Each mutation was transferred to a specialized transducing phage that carries the tryptophanase region of the Escherichia coli chromosome . The nine phages thus produced, and a tenth carrying a previously characterized tryptophanase mutation, were used to lysogenize a bacterial strain harbouring a mutation in the tryptophanase structural gene and also a suppressor of polarity . In no case was complementation observed; we conclude that there is no closely linked positive regulatory gene for tryptophanase.

Proc Natl Acad Sci U S A, 1979 Oct, 76(10), 5100 - 4
Homologous pairing in genetic recombination: complexes of recA protein and DNA; Shibata T et al.; recA protein, which is essential for general genetic recombination in Escherichia coli, promotes the homologous pairing of single-stranded DNA with double-stranded DNA to form a D loop . The amount of recA protein required for the reaction was directly proportional to the amount of single stranded DNA and was unaffected by similar variations in the amount of double-stranded DNA . The ATP analog, adenosine 5'-O-(3-thiotriphosphate) (ATP gamma S), which was not rapidly hydrolyzed by recA protein, blocked the formation of D loops but promoted the formation of stable complexes of recA protein and single-stranded DNA . These complexes, in turn, bound homologous or heterologous double-stranded DNA and partially unwound it . Because ATP gamma S competitively inhibited the ATPase activity of recA protein (Km/Ki approximately 300), we infer that ATP gamma S binds at a site that overlaps the site for ATP and that the functional complexes formed in the presence of the analog probably represent partial steps in the overall reaction . If the complexes formed in the presence of ATP gamma S reflect natural intermediates in the formation of D loops, recA protein must promote homologous pairing either by moving juxtaposed single-stranded and double-stranded DNA relative to one another or by forming and dissociating complexes reiteratively until a homologous match occurs.

Proc Natl Acad Sci U S A, 1979 Oct, 76(10), 4946 - 50
Fidelity of replication of phage phi X174 DNA by DNA polymerase III holoenzyme: spontaneous mutation by misincorporation; Fersht AR; DNA from phi X174 is replicated in vitro with a fidelity similar to that found genetically . A mutation of TAG leads to TGG may be induced, however, by varying the concentrations of deoxynucleoside triphosphates, with a frequency proportional to {dGTP}2/{dATP} . This complex concentration dependence is consistent with the active participation of a proofreading mechanism that hydrolytically excises mismatched base pairs as they are formed . A simple kinetic analysis predicts that the frequency of misincorporation depends on the ratio of incorrect to correct deoxynucleoside triphosphates times the concentration of the next triphosphate in the sequence to be added . This suggests that spontaneous mutation by misincorporation depends crucially on the composition of the deoxynucleoside triphosphate pool.

J Bacteriol, 1979 Oct, 140(1), 251 - 60
Physical characterization of ilv-lac fusions; Leathers TD et al.; Electron microscopic heteroduplex analysis and comparative restriction digests have been used to characterize lambda p123(209), the complementary pair of phages used in the Casadaban technique of gene fusion . Derivatives of lambda 1(209) constructed to carry fusions of the lac genes to the control regions of the ilvC and ilvEDA operons were also analyzed . These physical maps have provided confirmation of the genetic models for these constructions and physical specifications important in interpreting the behavior of these ilv-lac fusions.

J Bacteriol, 1979 Oct, 140(1), 246 - 50
Cyanobacterial ribonucleic acid polymerases recognize lambda promoters; Miller SS et al.; We compared the initiation specificities in vitro of deoxyribonucleic acid-dependent ribonucleic acid polymerases purified from two cyanobacteria, Fremyella diplosiphon and Anacystis nidulans, and from Escherichia coli . A restriction fragment made from lambda deoxyribonucleic acid was used as a template . The cyanobacterial and E . coli ribonucleic acid polymerases recognized the same lambda promoters but exhibited different sensitivities to the inhibitor heparin, suggsesting differences in the structure of the initiation complexes.

J Bacteriol, 1979 Oct, 140(1), 106 - 13
Structural and functional analysis of cloned deoxyribonucleic acid containing the trpR-thr region of the Escherichia coli chromosome; Gunsalus RP et al.; Specialized transducing phages containing the thr-trpR region of the Escherichia coli chromosome were derived from a strain with lambda prophage inserted in thr . Cloning of segments of the chromosomal deoxyribonucleic acid of one such lambda thr + trpR+ phage in various plasmid vectors established that a 1.3-kilobase BamHI fragment carried trpR+ intact . Strains with a multicopy plasmid vector containing the BamHI insert produced 20-fold-higher levels of trp aporepressor than did the wild-type strain of Escherichia coli . Similarly, induction of lambda thr + trpR+ lysogens resulted in increased aporepressor levels . The 1.3-kilobase trpR+ BamHI fragment was inserted in either orientation downstream from lambda pLN in a plasmid vector in which transcription from lambda pL was under the control of a temperature-sensitive lambda repressor . Induction established the orientation of transcription of trpR and led to the production of 100-fold-increased levels of trp aporepressor . A presumptive 23,500-dalton trpR+ polypeptide was detected by using lambda pLNtrpR+ plasmid deoxyribonucleic acid in a cell-free transcription-translation system.

Zentralbl Bakteriol {B}, 1979 Oct, 169(3-4), 253 - 64
{Evaluation of the viral contamination of the sea water after the emission of an effluent into the sea (author's transl)}; Hugues B et al.; Research of virus in the sea water has been made by the concentrated method of adsorption-elution on glass powder . --This method has enabled us to strike the balance on the concentration of virus in the sea water, from the emission to the bank . The frequency of isolation of virus in the bathing zone considered as healthy is very high . The concentration of virus is practically constant in the length of an axis, 200 m distant in comparison with the bank.--The increase of particles of virus in the sea, in the estuary of the emission, reflects in the same way in the bathing zone, 5 m away from the bank . The phenomenon of dilution of the effluent in the sea water doesn't seem to play a part.

J Gen Microbiol, 1979 Oct, 114(2), 341 - 8
Relationship of group P1 plasmids revealed by heteroduplex experiments: RP1, RP4, R68 and RK2 are identical; Burkardt HJ et al.; The molecular relationships of the IncP1 plasmids RP1, RP4, R68 and RK2 were tested by electron microscopic examination of heteroduplexes . In several hybridization experiments molecules were detected which had a 7.8% portion of incomplete reannealing . This 'heterologous region' could be explained by the typical renaturation behaviour of the transposon Tn1 . The identity of the Tn1 transposon present in RP1 and RP4 was proved by heteroduplex experiments with lambda phage DNA containing this transposon . These results indicated that the plasmids RP1 and RP4 are identical . Additional heteroduplex experiments between plasmids R68.45 and RP8 and between R68.45 and RK2 were performed . R68.45, a derivative of R68, has a small DNA insertion and RP8 can be regarded as a large insertion mutant of RP4; both insertions were used as single-stranded hybridization markers . From the hybrid molecules formed, it was deduced that R68 and RK2 are identical with RP1 and RP4 as far as molecular structure is revealed by the technique used.

Acta Pathol Microbiol Scand {C}, 1979 Oct, 87(5), 333 - 40
Adhesion and locomotion of human leukocytes in vitro; importance of protein coating; effect of lidocain, ethanol and endotoxin; Schreiner A et al.; The adhesion of leukocytes to glass beads in protein-free media was quantitatively high and not dependent on divalent cations . Addition of plasma, albumin or gelatin in increasing concentrations gradually reduced leukocyte adhesion, which then became increasingly dependent on divalent cations . Heat inactivation of plasma did not affect leukocyte adhesion . Leukocyte migration in glass capillary tubes, which was dependent on a heat labile plasma factor, was promoted by each of the proteins listed and by siliconizing the tubes . Leukocyte migration in millipore filters was enhanced when albumin was present in the cell starting compartment . Lidocain reduced both leukocyte adhesion to protein-coated glass and leukocyte migration in capillary tubes and millipores filters . Ethanol reduced leukocyte adhesion and leukocyte filter migration . E . coli endotoxin enhanced adhesion of leukocytes but inhibited their migration in tubes and filters . The findings indicate the existence of a relationship between adhesion and migration of leukocytes.

Proc Natl Acad Sci U S A, 1979 Oct, 76(10), 4922 - 6
Control features within the rplJL-rpoBC transcription unit of Escherichia coli; Barry G et al.; Gene fusions constructed in vitro have been used to examine transcription regulatory signals from the operon which encodes ribosomal proteins L10 and L7/12 and the RNA polymerase beta and beta' subunits (the rplJL-rpoBC operon) . Portions of this operon, which were obtained by in vitro deletions, have been placed between the ara promoter and the lacZ gene in the gene-fusion plasmid pMC81 developed by M . Casadaban and S . Cohen . The effect of the inserted DNA segment on the expression of the lacZ gene (in the presence and absence of arabinose) permits the localization of regulatory signals to discrete regions of the rplJL-rpoBC operon . An element that reduces the level of distal gene expression to one-sixth is located on a fragment which spans the rplL-rpoB intercistronic region . This strongly supports the idea that there is an attenuator in this region . The terminator for the operon is located on a fragment which spans the 3' end of the rpoC gene . The major promoter for the operon precedes the rplJ gene {Yamamoto, M . & Nomura, M . (1978) Proc . Natl . Acad . Sci . USA 75, 3891-3895 and Linn, T . & Scaife, J . (1978) Nature (London) 276, 33-37} and was not examined in this study . However, a weak promoter is observed on the fragment that spans the rplJ-rplL intercistronic region . Other regions of the operon may also contain weak promoters . The contribution of these elements to the regulation of this complex operon is discussed.

J Biochem (Tokyo), 1979 Oct, 86(4), 943 - 9
Enzyme immunoassay of pancreatic glucagon at the picogram level using beta-D-galactosidase as a label; Iwasa S et al.; An enzyme immunoassay of pancreatic glucagon was established by using E . coli beta-D-galactosidease {EC 3.2.1.23} as a marker . In order to increase the sensitivity of the immunoassay, different peptides obtained from glucagon fragments were used to produce the enzyme conjugate and the immunogen . Antiserum N6E raised against C-terminal fragment peptide (15-29) could be diluted to more than 1 : 100,000 in the assay and was highly specific for pancreatic glucagon . The antiserum reacted well with the C-terminal fragment peptide (21-29) as well as another fragment peptide (15-29) and pancreatic glucagon . The enzyme immunoassay using antiserum N6E and fragment peptide (21-29)-enzyme conjugate could detect as little as 1 to 2 pg of glucagon . The mean recovery of glucagon added to serum specimens was 104% and the coefficients of variation were 3.7-14.5% (within assay) and 9.0-18.5% (between assay).

J Gen Microbiol, 1979 Oct, 114(2), 477 - 81
Relationships among raffinose plasmids determined by the immunochemical cross-reaction of their alpha-galactosidases; Schmid K et al.; Plasmid-encoded alpha-galactosidase served as a marker enzyme for the recognition and comparison of raffinose (Raf) plasmids present in strains of Escherichia coli . Immunochemical relationships were established among Raf plasmids of 39 independent isolates from man and domestic animals (from three continents) by using antiserum against alpha-galactosidase . Immunodiffusion revealed three serological subclasses of alpha-galactosidase, which are correlated with the biological and geographical origin of the host strains . It is concluded that the raf determinants of all Raf plasmids tested have evolved from a common ancestor.

Arch Biol Med Exp (Santiago), 1979 Oct, 12(3), 415 - 26
Regulation of biosynthesis of aminoacyl-transfer RNA synthetases and of transfer-RNA in Escherichia coli; Morgan S et al.; We have isolated temperature resistant revertants from temperature sensitive E . coli strains containing either a thermolabile glutaminyl-tRNA synthetase or leucyl-tRNA synthetase . Among the revertants which still contained the thermolabile leucyl-tRNA synthetase we found two classes of regulatory mutants (leuX and leu Y) which have elevated levels of this enzyme . The leuX mutation specifies an operator-promoter region adjacent to the structural gene (leuS) for the enzyme . The leuY gene maps away from the leuS gene and codes for a protein . Using these mutants we demonstrated that the levels of leucyl-tRNA are related to the derepression of the leucine and isoleucine-valine operons . Among the revertants which still contained the thermolabile glutaminyl-tRNA synthetase were characterized three classes of mutants, glnT, glnU, and glnR . The glnT and glnU mutants contain elevated levels of tRNAgln, while the glnR mutant possesses elevated levels of glutaminyl-tRNA synthetase . The level of glutamine synthetase, the enzyme responsible for the formation of glutamine, is also derepressed in the glnT and glnR mutants.

Gastroenterol Jpn, 1979 Oct, 14(5), 432 - 5
Clinical investigation of serum deoxyribonuclease: I . Analysis of serum deoxyribonuclease activity in comparison with normal and after endoscopic retrograde pancreatography; Funakoshi A et al.; Serum Deoxyribonuclease (DNase) micro-assay method was developed using 32P-labelled E . coli DNA as substrate . The serum DNase showed maximum activity at pH 7.5 . It required Mg+ for activity, and was inhibited by EDTA or EGTA . The enzyme was also inhibited by actin (60-65%) or bovine pancreatic DNase I antibody (40-45%) . The serum DNase activity was markedly increased following endoscopic retrograde pancreatography (ERP) examination . These results imply that serum DNase activity is mostly at least 60-65% pancreatic DNase I.

J Bacteriol, 1979 Oct, 140(1), 20 - 7
Distribution of coenzyme F420 and properties of its hydrolytic fragments; Eirich LD et al.; The ability of hydrolytic products of coenzyme F420 to substitute for F420 in the hydrogenase and nicotinamide adenine dinucleotide phosphate-liniked hydrogenase systems of Methanobacterium strain M.o.H . was kinetically determined . The nicotinamide adenine dinucleotide phosphate-linked hydrogenase system was employed to quantitate the levels of F420 in a number of methanogenic bacteria as well as in some nonmethanogens . Methanobacterium ruminantium and Methanosarcina barkeri contained low levels of F420, whereas other methanogens tested contained high levels (100 to 400 mg/kg of cells) . F420 from six of the seven methanogens was tested by thin-layer electrophoresis and was found to be electrophoretically identical to that purified from Methanobacterium strain M.o.H . The only exception was M . barkeri, which contained a more electronegative derivative of F420 . Acetobacterium woodii, Escherichia coli, and yeast extract contained no compounds able to substitute for F420 in the nicotinamide adenine dinucleotide phosphate-linked hydrogenase system.

J Bacteriol, 1979 Oct, 140(1), 182 - 7
Purification and properties of a nicotinamide adenine dinucleotide-linked dehydrogenase that serves an Escherichia coli mutant for glycerol catabolism; Tang CT et al.; Glycerol:NAD+2-OXIDOREDUCTASE (EC 1.1.1.6) was purified to homogeneity from a mutant of Escherichia coli K12 that uses this enzyme, instead of ATP:glycerol 3-phosphotransferase (EC 2.7.1.30), as the first enzyme for the dissimilation of glycerol . Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate shows a subunit of 39,000 daltons . During electrophoresis under nondenaturing conditions, the protein migrates as two bands . These two forms, both of which are enzymatically active, appear to be dimers and octomers of the same subunit . The optimal pH for the oxidation of glycerol is about 10, and that for the reduction of dihydroxyacetone is about 6 . Glycerol dehydrogenation is highly activated by NH4+, K+, or Rb+, but strongly inhibited by N-ethylmalemide, 8-hydroxyquinoline, 1,10-phenanthroline, Cu2+, and Ca2+ . The enzyme exhibits a broad substrate specificity . In addition to glycerol, it act on 1,2-propanediol and several of its analogs.

Infect Immun, 1979 Oct, 26(1), 362 - 8
Attachment pili from enterotoxigenic Escherichia coli pathogenic for humans; Deneke CF et al.; Pili from enterotoxigenic Escherichia coli pathogenic for humans have been isolated by adsorption to the surface of erythrocytes followed by thermal elution . The pili are composed of two protein subunits with molecular weights of 13,100 and 12,500 as determined by sodium dodecyl sulfate-gel electrophoresis . These pili also bind to human buccal cells under temperature conditions (37 degrees C) which prevent the binding of these pili to the erythrocytes . Analogous temperature effects on binding have previously been observed with whole bacterial cells . This binding can be inhibited by antiserum prepared against the isolated pili.

Nature, 1979 Sep 27, 281(5729), 320 - 1
The stereochemical course of amino acid activation by methionyl- and tyrosyl-tRNA synthetases; Langdon SP et al.; Stereochemical analysis has long been recognised as a powerful tool for elucidating the mechanisms of chemical and enzyme-catalysed reactions . Although much is known about the stereochemical course of reactions at saturated carbon, phosphate and thiophosphate esters whose ligands to phosphorus are also tetrahedrally disposed, are capable in principle of revealing sterochemical information about events at the active site of enzymes that transform such substrates . Nucleotidyl transferases are a group of enzymes which in general selectively use one of the diastereoisomers of a nucleoside 5'(1-thiotriphosphate), such as isomers A and B of adenosine 5'(1-thiotriphosphate), designated ATP alpha S-A and ATP alpha S-B, and allow investigation of the stereochemical course of nucleotidyl transfer . We have developed a simple method based on 31P nuclear magnetic resonance spectroscopy for determining the stereochemical course of these reactions, and using this method show here that the nucleotidyl transfer step in two aminoacyl-tRNA synthetases from Escherichia coli occurs with inversion of configuration at phosphorus . These observations greatly constrain the mechanistic possibilities for these enzymes, and are interpreted most simply as a direct 'in line' transfer from ATP to the amino acid.

Biochim Biophys Acta, 1979 Sep 27, 564(2), 311 - 21
Action of thiazolidine-2-carboxylic acid, a proline analog, on protein synthesizing systems; Busiello V et al.; Thiazolidine-2-carboxylic acid, or beta-thiaproline, is a proline analog in which the beta methylene group of proline is substituted by a sulfur atom . It has been deomonstrated that beta-thiaproline is activated and transferred to tRNAPro by Escherichia coli and rat liver aminoacyl-tRNA synthetases, and inhibits proline incorporation into polypeptides in protein synthesizing systems from E . coli, rat liver or rabbit reticulocytes . In mammalian systems beta-thiaproline inhibits also leucine incorporation; in rabbit reticulocyte lysate it inhibits ribosome run-off . Both these effects may be explained by the fact that beta-thiaproline once incorporated into the growing polypeptide chain impairs its further elongation, as shown by experiments made with puromycin . All tests were performed in comparison with thiazolidine-4-carboxylic acid, or gamma-thiaproline, another proline analog having the gamma methylene group substituted by a sulfur atom; it was shown that in all the reactions studied both compounds act as competitive inhibitors of proline . Some differences in the effects of the two analogs have been evidenced: in almost all the reactions and mainly in the whole protein synthesizing systems, beta-thiaproline shows an higher inhibitory activity.

Biochim Biophys Acta, 1979 Sep 27, 564(2), 225 - 34
Optimization of conditions for the in vitro formation of hybrid DNA molecules by DNA ligase; Graf H; Conditions for the ligation with T4 induced DNA ligase of two DNA molecules via their complementary sticky ends have been established which lead preferentially to the formation of hybrid molecules . This is demonstrated with two combinations of parent molecules varying greatly in their relative molecular weights . In one case the intact hybrid molecule could be directly isolated . In addition a DNA dependent quantitative electrophoretic assay for DNA ligase activity is described which does not need a radioactively labeled substrate . The ligation procedure has been shown to be useful in molecular cloning experiments.

Biochim Biophys Acta, 1979 Sep 27, 564(2), 212 - 24
Circular dichroism anisotrophy of DNA with different modifications at N7 of guanine; Zavriev SK et al.; The complexex DNA-Ag1+, DNA-Cu1+, protonated DNA and DNA methylated at N7 of guanine were oriented by pumping the solutions through a multicapillary cell in the direction of a light beam . The CD components along the DNA axis, delta epsilon parallel, and normal to it, 2 delta epsilon perpendicular, were calculated from the CD spectra of the oriented samples by the method of Chung and Holzwarth, (1975) J . Mol . Biol . 92, 449--466 . It was shown that in most cases, except that of the protonated DNA, the degree of orientation was only slightly less than that for pure DNA . This demonstrated the absence of aggregation and of appreciable denaturation . In all cases the modifications of DNA give rise to a negative component 2 delta epsilon perpendicular, whose magnitude increased as the extent of modification increased . From both the CD spectra of non-oriented samples and the absorption spectra, an inference is drawn that Ag1+ and Cu1+ are attached to the same site as CH3 groups i.e., to the N7 atom of guanine . Proton transfer along the H-bond from the N1 atom of G to the N3 atom of the complementary cytosine is suggested to be a result of the modifications, although the case of H+-DNA may differ from the others . Based on the CD spectra for the anisotropic components, delta epsilon parallel and 2 delta epsilon perpendicular, it is proposed that ligand binding is accompanied by winding of the DNA helix.

J Biol Chem, 1979 Sep 25, 254(18), 8796 - 800
Purification and characterization of a ribosome dissociation factor (eukaryotic initiation factor 6) from wheat germ; Russell DW et al.; A wheat germ ribosome dissociation factor, eukaryotic initiation factor 6 (eIF-6), has been purified almost to homogeneity from the 25 to 40% ammonium sulfate fraction of the postribosomal supernatant . This dissociation factor is distinct from initiation factor eIF-3 and its chromatographic properties permit its separation from the known wheat germ initiation factors . Under certain conditions, eIF-6 stimulates the incorporation of amino acids into polypeptides in a partially fractionated wheat germ cell-free system . The eight-step purification procedure developed includes chromatography on DEAE-cellulose, phosphocellulose, Sephadex G-75, and hydroxyapatite and yields a dissociation factor more than 80% pure . The purified factor is composed of a single polypeptide chain with a molecular weight of approximately 23,000 as determined by gel filtration chromatography and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis . It is an acidic protein which is heat labile and is inactivated by treatment with N-ethylmaleimide . The dissociation factor is much more effective in preventing the reassociation of 40 S and 60 S ribosomal subunits than in directly dissociating 80 S ribosomes . Like Escherichia coli IF-3, about 10 pmol of the dissociation factor are required to dissociate 1 pmol of ribosomes.

Nucleic Acids Res, 1979 Sep 25, 7(2), 517 - 28
Determination of the recognition sites of cytosine DNA-methylases from Escherichia coli SK; Nikolskaya II et al.; Two different cytosine DNA-methylases, NI and GII, are present in Escherichia coli SK . The GII methylase recognizes the five-member symmetric sequence: 5'...NpCpCpApGpGpN...3' . This sequence is identical with the recognition site of the hsp II type determined by RII plasmid but, in contrast to RII methylase, the GII enzyme methylates cytosine located on the 5' side of the site . By analogy with the isoshizomery of the restricting endonucleases, RII and GII DNA methylaeses may be called isomethymers which recognize the same site but methylate different bases . Since the phage of the SK and hsp II phenotypes is effectively restricted in respective cells it may be assumed that the isomethymeric modification does not provide any protection against the corresponding restrictases . NI methylase recognizes the five-member symmetric site which represents an inverted sequence of the GII site: 5'...NpGpGpApCpCpN...3' . In this case cytosine at the 3'-end of the recognition site is methylated.

Nucleic Acids Res, 1979 Sep 25, 7(2), 501 - 15
The glutamyl-tRNA synthetase of Escherichia coli: substrate-induced protection against its thermal inactivation; Kern D et al.; The substrates-induced protection against the heat-inactivation of the glutamyl-tRNA synthetase has been investigated . tRNAGlu and ATP protect efficiently the enzyme, whereas glutamate does not . In the presence of tRNAGlu, glutamate induces an additional protection to that given by the tRNAGlu alone . A weak synergism was observed between ATP and tRNAGlu, whereas no synergism was detected between ATP and glutamate . These results suggest that tRNAGlu and ATP, but not glutamate are able to bind to the free enzyme form; glutamate binds only to the Enzyme.tRNAGlu and to the Enzyme.tRNAGlu.ATP complexes . The presence of the three substrates induces a higher stabilization of the enzyme than that expected from the protection observed for the various other substrates combinations, suggesting the existence of a marked synergism between the three substrates against the heat-inactivation of the enzyme . The protection constants determined from this study are similar to the dissociation constants determined by direct binding experiments and to the Km values determined kinetically.

Nucleic Acids Res, 1979 Sep 25, 7(2), 465 - 80
Binding of magnesium ions and ethidium bromide: comparison of ribosomes and free ribosomal RNA; Elson D et al.; Comparative studies of free ribosomal RNA and ribosomes were made with two probes, Mg++ ions and ethidium bromide, which interact with RNA in different ways . Mg++ . E . coli 16 S rRNA and 30 S ribosomes were equilibrated with four different buffers . Equilibration required several days at 4 degrees and several hours at 37 degrees . In all buffers ribosomes bound more Mg than free rRNA, the difference sometimes reaching 20--30% . Ribosomes were more resistant than free rRNA to heat denaturation and their denaturation was more highly cooperative . Ribosomes that bound more Mg++ had higher denaturation temperatures . Ethidium bromide . Fluorescence enhancement studies of ethidium intercalation showed the free 16 S rRNA to have 50--80 binding sites per molecule . A large fraction of these sites were present and accessible in the ribosome, but their ethidium-binding constants were reduced by an order of magnitude . In addition, free rRNA contained a small number of very strong binding sites that were virtually absent in the ribosomes.

Nucleic Acids Res, 1979 Sep 25, 7(2), 453 - 64
The synthesis of oligodeoxyribonucleotides using RNA ligase; Hinton DM et al.; T4 RNA ligase catalyzes the addition of a single deoxyribonucleoside 3',5'-bisphosphate to the 3'-hydroxyl of oligodeoxyribonucleotides (Hinton et al . (1978) Biochemistry 17, 5091) . We have determined improved conditions for this reaction which give yields equal to or greater than 85% when any of five common deoxyribonucleoside bisphosphate (pdAp, pdCp, pdGp, pdTp, or pdUp) are added to dA(PDA)4 . A low ATP concentration, which is constantly maintained by a regeneration system composed of phosphocreatine, creatine kinase, and myokinase, contributes to the attainment of high yields . The addition of RNase A and spermine also enhances the rates and yields of the reactions . These conditions facilitate the use of RNA ligase as a reagent for the stepwise synthesis of DNA of defined sequence.

Nucleic Acids Res, 1979 Sep 25, 7(2), 401 - 16
Studies on gene control regions XII . The functional significance of a lac operator constitutive mutation; Fisher EF et al.; The functional significance of a lac operator constitutive mutation has been determined . The transition adenine-thymine to guanine-cytosine was shown to be a constitutive mutation simply because thymine contains the functionally important 5-methyl group whereas cytosine does not . The remainder of the base pair is of no consequence . The experimental approach was to synthesize various modified operators containing cytosine, 5-methyl-cytosine, and 5-bromocytosine . The synthetic operator containing a guanine-cytosine base pair displays an eightfold reduction in stability with lac repressor whereas the operator containing 5-methylcytosine binds repressor at least as tightly as does the wild type sequence . Results published previously have shown that a similar decrease in stability of the repressor-operator complex can be obtained simply by substituting uracil for thymine or by inverting the base pair to thymine-adenine . All these results taken together implicate the thymine 5-methyl as the only important functional group recognized by the lac repressor at this base pair . Further confirmation of this conclusion was obtained by substitution of 5-bromocytosine and 5-bromouracil at this base pair . Both altered the stability of the repressor-operator complex by about the same percent suggesting that the bromine atom was the important determinant of complex stability for 5-bromopyrimidine analogs.

Nucleic Acids Res, 1979 Sep 25, 7(2), 361 - 75
Sequence of 1019 nucleotides encompassing one of the inverted repeats from the yeast 2 micrometer plasmid; Hindley J et al.; A sequence of 1019 nucleotides encompassing one of the 600 base inverted repeats and non-repeated flanking regions has been determined in the type A yeast 2 micrometers plasmid cloned in pMB9 . Methods are described for applying the Maxam-Gilbert sequencing procedure to DNA fragments labelled at the 3'-end using a T4-polymerase exchange/repair reaction and for sequencing 5'-end labelled fragments using dideoxy-nucleotides as chain terminators in the presence of E . coli DNA polymerase (nach Klenow) . A notable feature of the sequence is its unusual content of symmetry elements . In one region of 140 nucleotides, 137 are involved in a complex arrangement of direct and inverted repeats linked by palindromic sequences.

Nucleic Acids Res, 1979 Sep 25, 7(2), 305 - 20
Molecular cloning and nucleotide sequence of the human growth hormone structural gene; Roskam WG et al.; An almost complete cDNA copy of human growth hormone has been cloned and sequenced . The nucleotide sequence confirms the known protein sequence and predicts the sequence of a precursor region of 26 amino acids . We have compared the nucleotide sequence to that for the homolgous proteins, rat growth hormone and human chorionic somatomammotropin (Seeburg et al . and Shine et al., Nature 270, 486 (1977)) . There appears to be evolutionary conservation of mRNA sequence features not related to protein structure.

J Biol Chem, 1979 Sep 25, 254(18), 9277 - 83
Isolation of recombinant plasmids bearing cDNA to hen ovomucoid and lysozyme mRNAs; Buell GN et al.; A large library of hen oviduct cDNA-pCR1 recombinant plasmids has been established in Escherichia coli X1776 . From this library, ovomucoid cDNA and lysozyme cDNA-bearing plasmids have been identified . One of these plasmids, pMu7, yielded the sequence of the 3'-untranslated region of ovomucoid mRNA.

J Biol Chem, 1979 Sep 25, 254(18), 9130 - 4
Kinetics of the utilization of medium and long chain fatty acids by mutant of Escherichia coli defective in the fadL gene; Nunn WD et al.; Experiments were performed to assess the role of the fadL gene in Escherichia coli . These studies have revealed that this organism requires a functional fadL gene in order to (i) transport optimally the fatty acids C10 to C18:1 into the cell, (ii) optimally grow on and oxidize C10 to C18:1 fatty acids, and (iii) incorporate efficiently C12 to C18:1 fatty acids into its membrane phospholipids . A defect in the fadL gene does not prevent E . coli from optimally utilizing fatty acids with chain lengths less than 10 carbon atoms . These results suggest that the fadL gene governs a transport component(s) which is required for the optimal transport of fatty acids with chain lengths greater than 9 carbon atoms.

J Biol Chem, 1979 Sep 25, 254(18), 9090 - 3
Studies on the function of two adjacent N6,N6-dimethyladenosines near the 3' end of 16 S ribosomal RNA of Escherichia coli . II . The effect of the absence of the methyl groups on initiation of protein biosynthesis; Poldermans B et al.; The effect of the presence or absence of methyl groups on the N6 atoms of two adjacent adenosines near the 3' end of 16 S rTNA of Escherichia coli on initiation of protein biosynthesis has been studied using wild type (methylated) and kasugamycin-resistant (unmethylated) E . coli ribosomes (see preceding paper (Poldermans, B., Goosen, N., and Van Knippenberg, P . H . (1979) J . Biol . Chem . 254, 9085--9089)) . Conditions of pH, temperature, and ionic strength at which binding of fMet-tRNA to ribosomes proceeds maximally are the same for wild type and mutant ribosomes . Mg2+- and factor-dependent dissociation of ribosomes as well as the association of the subunits is also the same for methylated and unmethylated ribosomes . Binding of fMet-tRNA to wild type and to mutant 70 S ribosomes requires the same amount of the three initiation factors . However, optimal fMet-tRNA binding to unmethylated 30 S ribosomes needs more of initiation factor 3 than does binding to methylated 30 S ribosomes, provided that initiation factor 1 is absent . This difference is completely abolished when mutant 30 S ribosomes are methylated using purified methylase from the wild type strain and the methyl donor S-adenosylmethionine.

Biochim Biophys Acta, 1979 Sep 21, 556(2), 233 - 43
Architecture of the outer membrane of Escherichia coli K12 . IV . Relationship between outer membrane particles and aqueous pores; van Alphen L et al.; The hypothesis that intramembraneous particles, observed in the outer membrane of Escherichia coli by freeze-fracture electron microscopy, are the morphological representation of aqueous pores, was tested . A mutant which is deficient in five major outer membrane proteins, b, c, d, e and the phage lambda receptor protein, contains a largely decreased number of intramembraneous particles and also shows a greatly decreased rate of uptake of several solutes . In derivatives of this strain which contain only one of these proteins in large amounts a strong decrease of the number of intramembraneous particles is observed, which is accompanied by a complete restoration of the rate of uptake of those solutes which use pores in which the protein in question is involved . The results provide strong evidence for the notion that an individual pore contains only one protein species, a property which has been found earlier for individual particles . The observed correlation between particles and equeous pores strongly supports the hypothesis that the particles are the morphological representation of pores . Implications of this hypothesis for the structure of the particles are discussed.

Nature, 1979 Sep 20, 281(5728), 191 - 5
Single strands induce recA protein to unwind duplex DNA for homologous pairing; Cunningham RP et al.; Single-stranded DNA, whether homologous or not, stimulates purified Escherichia coli recA protein to unwind duplex DNA . This helps to explain how recA promotes a search for homology in genetic recombination . As oligodeoxynucleotide also stimulate unwinding, a common mechanism may relate the function of recA protein in recombination to other functions (SOS) induced by oligonucleotides.

Biochemistry, 1979 Sep 18, 18(19), 4165 - 9
Thallous ion is accumulated by potassium transport systems in Escherichia coli; Damper PD et al.; The accumulation of 204T1+ by Escherichia coli occurs primarily via either of two K+ transport systems called Kdp and TrkA . T1+ influx is inhibited and T1+ efflux is stimulated by the addition of K+ to the assay medium . Mutants defective in both the Kdp and TrkA systems accumulate little T1+ . Uptake of triphenylmethylphosphonium, a lipid-soluble cation whose distribution is widely used to estimate the membrane electrical potential in bacteria, occurs to about the same extent in mutants that accumulate little T1+ as in strains that accumulate T1+ to high levels . These findings indicate that T1+ may be useful as a probe of bacterial K+ transport systems but is not a reliable indicator of the membrane electrical potential in E . coli.

Biochemistry, 1979 Sep 18, 18(19), 4155 - 8
Peptidyl transfer ribonucleic acid hydrolase activity of proteinase k; Vidales FJ et al.; Proteinase k, a seryl-protease obtained from Tritirachium album, is able to specifically hydrolyze N-blocked aminoacyl transfer ribonucleic acids (tRNAs) . The blocked amino acid is released, and the tRNA molecule remains able to be recharged by its cogante amino acid . Aminoacyl-tRNAs are highly resistant to hydrolysis by the protease . This activity is not due to contamination of the protease preparation . A commercial protease from Streptomyces griseus displayed a similar activity, while trypsin, chymotrypsin, and papain unspecifically hydrolyzed all charged tRNAs tested . The characteristics of the hydrolysis performed by proteinase k closely resemble the peptidyl-tRNA hydrolase activity described in different cells as a scavenger for the peptidyl-tRNA that eventually falls from the polysomes . Out results warn about a hasty identification of any N-blocked aminoacyl-tRNA hydrolase activity in the cytoplasm as an independent peptidyl-tRNA hydrolase.

Biochemistry, 1979 Sep 18, 18(19), 4144 - 7
In vivo studies on the incorporation of microinjected acidic proteins of the large ribosomal subunit from Escherichia coli and artermia salina into oocyte ribosomes from Xenopus laevis; Kalthoff H et al.; Tritium-labeled acidic proteins from the large ribosomal subunit of Artermia salina or Escherichia coli were microinjected into the cytoplasm of stage IV/V oocytes from Xenopus laevis . eL12 from the large ribosomal subunit of A . salina but not L7/L12 or L7/L12--L10 from E . coli is specifically incorporated into 60S ribosomal subunits of oocytes . This incorporation is not significantly inhibited by actinomycin D . Incorporation of eL12 into the 60S subunits occurs in enucleated oocytes, suggesting that active ribosomal ribonucleic acid synthesis and ribosome assembly as well are not prerequired for this reaction . Apparently the incorporation proceeds via an exchange reaction between a free cytoplasmic pool of eL12 and ribosomal eL12.

Biochemistry, 1979 Sep 18, 18(19), 4116 - 20
Mechanistic studies on deoxyribonucleic acid dependent ribonucleic acid polymerase from Escherichia coli using phosphorothioate analogues . 1 . Initiation and pyrophosphate exchange reactions; Yee D et al.; The diastereomers of adenosine 5'-O-(1-thiotriphosphate) (ATP alpha S) and adenosine 5'-O-(2-thiotriphosphate) (ATP beta S) can replace adenosine triphosphate (ATP) in the initiation reaction catalyzed by deoxyribonucleic acid (DNA) dependent ribonucleic acid (RNA) polymerase from Escherichia coli . In both cases, the Sp diastereomer is a better initiator than the Rp isomer . The diasteromers of 3'-uridyl 5'-adenosyl ,O-phosphorothioate {Up(S)A} can replace UpA in the primed initiation reaction catalyzed by RNA polymerase; however, the Rp diastereomer is a better initiator than the Sp isomer . By using ATP or CpA as initiator and UTP alpha S, isomer A, as substrate, we determined the stereochemical courses of both the initiation and primed initiation reactions, respectively, with T7 DNA template and found them to proceed with inversion of configuration . Determination of the stereochemical course of the pyrophosphate exchange reaction catalyzed by RNA polymerase provides evidence that this reaction is the reverse of the phosphodiester bond-forming reaction.

Biochemistry, 1979 Sep 18, 18(19), 4090 - 5
Interaction of divalent cations with beta-galactosidase (Escherichia coli); Huber RE et al.; Although the addition of various divalent metals to beta-galactosidase resulted in apparent activation, only Mg2+ and Mn2+ actually did activate . The apparent activation by the other divalent metals was shown to be due to Mg2+ impurities . Calcium did not activate, but experiments suggested that it did bind . Other divalent metals which were studied failed to bind . The dissociation constants for Mg2+ and Mn2+ were 2.8 X 10(-7) and 1.1 X 10(-8) M, respectively, and in each case one ion bound per monomer . These constants corresponded very closely to apparent values which were obtained from activation studies . The apparent binding constant for Ca2+, obtained from competition studies, was 1.5 X 10(-5) M . Data were obtained which showed that Mg2+, Mn2+, and Ca2+ all compete for binding at a single site . Of interest and of possible molecular biological importance was the observation that, while Mg2+ bound noncooperatively (n = 1.0), Mn2+ did so in a highly cooperative manner (n = 3.4) . The binding of Mn2+ (as compared to Mg2+) resulted in a twofold drop in the Vmax for the hydrolysis and transgalactosylis reactions of lactose but had little effect on the Vmax of hydrolysis of allolactose, p-nitrophenyl beta-D-galactopyranoside (PNPG), or o-nitrophenyl beta-D-galactopyranoside (ONPG); Km values were not effected differently for any of the substrates by Mn2+ as compared to Mg2+ . When very low levels of divalent metal ions were present (0.01 M EDTA added) or when Ca2+ was bound with lactose as the substrate, a greater decrease was observed in the rate of the transgalactosylic reaction than in the rate of the hydrolytic reaction, and the Km values for lactose and ONPG were increased . Of the three divalent metal ions which bound to beta-galactosidase, only Mn2+ had significant stabilizing effects toward denaturing urea and heat conditions.

Science, 1979 Sep 14, 205(4411), 1140 - 2
Molecular cloning of polyoma virus DNA in Escherichia coli: oncogenicity testing in hamsters; Israel MA et al.; Inoculation of suckling hamsters with 2 x 10(8) live cells of Escherichia coli K12 strain chi1776, carrying the complete genome of polyoma virus in a recombinant plasmid, failed to induce tumors in any of 32 recipients . Also, lambda phage DNA and particles with a monomeric insert of polyoma DNA did not induce tumors . Purified recombinant plasmid DNA, as well as phage particles and DNA containing a head-to-tail dimer of polyoma DNA, showed a low degree of oncogenicity, comparable to that of polyoma DNA prepared from mouse cells . These findings support the previous conclusions, based on infectivity assays in mice, that propagation of polyoma virus DNA as a component of recombinant DNA molecules in E . coli K12 reduces its biologic activity many orders of magnitude relative to the virus itself.

Biochim Biophys Acta, 1979 Sep 12, 570(1), 179 - 86
Immobilization of Escherichia coli cells containing aspartase activity with kappa-carrageenan . Enzymic properties and application for L-aspartic acid production; Sato T et al.; Whole cells of Escherichia coli having high aspartase (L-asparate ammonialyase, EC 4.3.1.1) activity were immobilized by entrapping into a kappa-carrageenan gel . The obtained immobilized cells were treated with glutaraldehyde or with glutaraldehyde and hexamethylenediamine . The enzymic properties of three immobilized cell preparations were investigated, and compared with those of the soluble aspartate . The optimum pH of the aspartase reaction was 9.0 for the three immobilized cell preparations and 9.5 for the soluble enzyme . The optimum temperature for three immobilized cell preparations was 5--10 degrees C higher than that for the soluble enzyme . The apparent Km values of immobilized cell preparations were about five times higher than that of the soluble enzyme . The heat stability of intact cells was increased by immobilization . The operational stability of the immobilized cell columns was higher at pH 8.5 than at optimum pH of the aspartase reaction . From the column effluents, L-aspartic acid was obtained in a good yield.

J Biol Chem, 1979 Sep 10, 254(17), 8641 - 5
Identification by affinity chromatography of the eukaryotic ribosomal proteins that bind to 5.8 S ribosomal ribonucleic acid; Ulbrich N et al.; The proteins that bind to rat liver 5.8 S ribosomal ribonucleic acid were identified by affinity chromatography . The nucleic acid was oxidized with periodate and coupled by its 3'-terminus to Sepharose 4B through and adipic acid dihydrazide spacer . The ribosomal proteins that associate with the immobilized 5.8 S rRNA were identified by polyacrylamide gel electrophoresiss: they were L19, L8, and L6 from the 60 S subunit; and S13 and S9 from the small subparticle . Small amounts of L14, L17', L18, L27/L27', and L35', and of S11, S15, S23/S24, and S26 also were bound to the affinity column, but whether they associate directly and specifically with 5.8 S rRNA is not known . Escherichia coli ribosomal proteins did not bind to the rat liver 5.8 S rRNA affinity column.

J Biol Chem, 1979 Sep 10, 254(17), 8679 - 89
Gene amplification causes overproduction of the first three enzymes of UMP synthesis in N-(phosphonacetyl)-L-aspartate-resistant hamster cells; Wahl GM et al.; Mutant Syrian hamster cells resistant to N-(phosphonacetyl)-L-aspartate (PALA), a transition state analog inhibitor of aspartate transcarbamylase, overproduce CAD, a multifunctional protein which catalyzes the first three reactions of de novo UMP biosynthesis . Increased levels of a single mRNA cause the overproduction of CAD in all PALA-resistant mutants examined thus far . A recombinant plasmid containing a 2,3-kilobase insert complementary to the 3'-proximal region of this 7.9-kilobase mRNA has been prepared and used to show that the CAD gene is amplified in each of the 10 PALA-resistant mutants examined . Rates of association of CAD sequences in DNA isolated from PALA-sensitive and PALA-resistant cells with labeled plasmid DNA indicated that the degree of amplification is approximately equal to the degree of overproduction of protein and mRNA in each mutant . The patterns of digestion of these DNAs with restriction enzymes confirmed this result and showed that the lower limit for the size of the amplified unit is 19 kilobases, much larger than the mRNA . A comparison of restriction endonuclease digests of the cloned cDNA with digests of genomic DNA indicated that part of this difference is attributable to intervening sequences in the CAD gene . A 10.2-kilobase RNA which contains CAD sequences is found in cytoplasmic fractions from some PALA-resistant mutants but not in wild type cells . Restriction patterns were analyzed by a new method in which fragments of DNA are transferred from agarose gels to diazo paper with a high efficiency which is independent of size.

J Biol Chem, 1979 Sep 10, 254(17), 8590 - 3
Fumarate reductase of Escherichia coli . Elucidation of the covalent-flavin component; Weiner JH et al.; Fumarate reductase is a membrane-bound terminal oxidase which is induced when Escherichia coli is grown anaerobically . The purified enzyme is composed of two polypeptide chains of 69,000 and 24,000 daltons and contains 1 mol of covalently bound flavin adenine dinucleotide per mol of enzyme . Fluorescence scanning of SDS-polyacrylamide gels of the protein shows that the flavin is attached to the large subunit . The hypsochromic shift of the 372 nm band of riboflavin to 350 nm in both native fumarate reductase and a flavin peptide released by proteolytic digestion indicates that the flavin is attached via position 8 alpha of riboflavin . Based on the spectral properties and pH-fluorescence dependence we have identified the linkage as 8 alpha-{N(3)-histidyl}FAD.

J Biol Chem, 1979 Sep 10, 254(17), 8584 - 9
A pleiotropic defect of membrane synthesis in a thermosensitive mutant tsC42 of Escherichia coli; Yamato I et al.; Synthesis of membrane proteins in a thermosensitive mutant of Escherichia coli K12, tsC42, that has a defect in a mechanism of cell cycle-dependent duplication of membrane enzymes was examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis . The cells were labeled differentially with {14C}- and {3H}arginine and the membrane proteins synthesized at nonpermissive and permissive temperatures were compared . The results showed that at the nonpermissive temperature, the syntheses of cytoplasmic membrane proteins and outer membrane proteins were reduced more than 70% and 50%, respectively . No significant accumulation of precursor molecules of membrane proteins at the nonpermissive temperature was detected in pulse-chase experiments . It is therefore assumed that the mutant has a defect in a gene that regulates the biosynthesis of many membrane proteins.

J Biol Chem, 1979 Sep 10, 254(17), 8295 - 307
Evidence for new factors in the coordinate regulation of energy metabolism in Escherichia coli . Effects of hypoxia, chloramphenicol succinate, and 2,4-dinitrophenol on glucose utilization, glycogen synthesis, adenylate energy charge, and hexose phosphates during the first two periods of nitrogen starvation; Dietzler DN et al.; We studied the effects of decreased aeration, chloramphenicol succinate, and 2,4-dinitrophenol on the cellular rates of glycogen synthesis and glucose utilization and on the cellular concentrations of adenine nucleotides, glucose 6-phosphate, fructose 1,6-diphosphate, and phosphoenolpyruvate during the first two periods of nitrogen starvation of Escherichia coli W4597(K) . A quantitative relationship between the changes in the rates and the accompanying changes in the hexose phosphates is demonstrated . However, the relationship for glycogen synthesis is different in different sets of metabolic conditions . We suggest that this difference reflects a change in the steady state level of a previously unknown effector of ADP-glucose synthetase (glucose 1-phosphate adenylyltransferase, EC 2.7.7.27) the rate-limiting enzyme of bacterial glycogen synthesis . We show that the properties of the hypothetical in vivo effector are consistent with the inhibitory effects of ppGpp (guanosine 3'-diphosphate 5'-diphosphate) and pppGpp (guanosine 3'-diphosphate 5'-triphosphate) on this enzyme in vitro . In addition, tetracycline, an inhibitor of the synthesis of these nucleotides, apparently prevents the change in the quantitative relationship . The relationship between glucose utilization and the hexose phosphates is altered at the transition to Period II of nitrogen starvation . We propose that this change reflects the alteration of the cellular steady state level of an unknown effector of the glucose phosphotransferase system . In contrast to the ATP-hexose phosphate system of shared regulatory effects, the specific effects of the unknown effectors allow the rates of glucose utilization and glycogen synthesis to be altered independently of each other and independently of changes in the rate of glycolysis . This independence allows a greater latitude of response for the individual pathways in more severe metabolic stress or in accommodating the metabolic changes necessary for long term survival.

J Biol Chem, 1979 Sep 10, 254(17), 8276 - 87
Regulation of glycogen synthesis and glucose utilization in Escherichia coli during maintenance of the energy charge . Quantitative correlation of changes in the rates of glycogen synthesis and glucose utilization with simultaneous changes in the cellular levels of both glucose 6-phosphate and fructose 1,6-diphosphate; Dietzler DN et al.; Treatment of nitrogen-starved cultures of Escherichia coli W4597(K) with sodium azide results in simultaneous changes in both glucose 6-phosphate and fructose 1,6-diphosphate as well as in the rate of glycogen synthesis . Based on these observations, a comprehensive equation was developed which relates the cellular levels of both of these hexose phosphates with the rate of glycogen synthesis . This relationship apparently represents the interaction in vivo between the rate-limiting enzyme of bacterial glycogen synthesis, glucose 1-phosphate adenylyltransferase (adenosine diphosphoglucose synthetase, EC 2.7.7.27), and its substrate glucose 1-phosphate (reflected by glucose 6-phosphate) and its major allosteric activator fructose diphosphate . The form of the equation that describes this relationship was determined from studies presented here of the kinetic properties of the E . coli W4597(K) enzyme in the presence of physiological concentrations of its substrates and modulators . We show here and in subsequent reports of this series that the comprehensive relationship between glycogen synthesis and hexose phosphates can serve as a reference to evaluate the possible participation of new factors in the regulation of glycogen synthesis . Treatment with NaN3 did not change the cellular level of glucose 1-phosphate adenylyltransferase . The value of the adenylate energy charge, (ATP + 1/2 ADP)/(ATP + ADP + AMP), was maintained despite losses of up to 35% in cellular adenylates . The quantitative co-variance between hexose phosphates and the cellular rate of glucose utilization that we previously described for other metabolic conditions was also observed in the azide-treated cultures . We integrate the new information into the system of coordinated regulation of glycogen synthesis, glycolysis, and glucose utilization that we proposed previously.

J Biol Chem, 1979 Sep 10, 254(17), 8099 - 102
Isolation and characterization of recombinant clones containing the chicken adult beta-globin gene; Ginder GD et al.; We have isolated and characterized two independent clones containing the chicken adult beta-globin gene . Each clone contains a 6.2-kilobase-pair Eco RI restriction fragment of chicken erythrocyte DNA inserted into the vector, lambda gtWES . lambda B . The orientation of the inserted fragment is opposite in the two clones . Characterization of the clones by electron microscopic R-loop studies, by restriction enzyme mapping, and by filter hybridization shows that the adult beta-globin gene is interrupted by at least one small and one large intervening sequence . In addition to the complete adult beta-globin gene, at least part of a second beta-globin-like gene was identified about 2.7 kilobase pairs from the 3'-end of the adult gene . The two independent clones, while very similar, do differ at two Msp I restriction endonuclease sites in regions flanking the adult beta-globin gene.

J Biol Chem, 1979 Sep 10, 254(17), 8256 - 62
Biophysical properties of a major membrane phospholipid, dielaidoylphosphatidylethanolamine, found in an Escherichia coli fatty acid auxotroph; Yang RD et al.; Dielaidoylphosphatidylethanolamine, a principal lipid component of membranes of Escherichia coli fatty acid auxotrophs enriched in elaidic acid, has been studied by paramagnetic resonance, fluorescence, and calorimetric methods . EPR measurements with perdeutero-di-tert-butylnitroxide and 2,2,6,6-tetramethyl piperidine-1-oxyl indicate that, when dispersed in aqueous media, this phospholipid undergoes an abrupt order leads to disorder transition at 37.5 degrees C and 36.5 C, respectively . A similar transition temperature is suggested by experiments with 9-doxyl-dimyristoylphosphatidylethanolamine (DEPE) . cis- and trans-Parinaric-acid fluorescence polarization measurements indicate that the midpoint of this transition occurs at 34.0 degrees C and 35.5 degrees C, respectively . Differential scanning calorimetry of DEPE revealed a single, sharp endotherm at 38.5 degrees C with increasing temperature; two exotherms of similar magnitude were observed at 36.5 degrees C and 34.5 degrees C upon cooling . This double transition was not observed by any of the other methods . From these results we conclude that the major structural transition at 30-31 degrees C observed previously with 5-, 12-, and 16-doxyl stearate in intact E . coli membranes is due to the DEPE present (Morrisett, J.D., Pownall, H.J., Plumlee, R.T., Smith, L.C., Zehner, Z.E., Esfahani, M., and Wakil, S.J . (1975) J . Biol . Chem . 250, 6969-6976).

J Biol Chem, 1979 Sep 10, 254(17), 8404 - 8
DNA-directed in vitro synthesis of beta-galactosidase . Purification and characterization of stimulatory factors in an ascites extract; Kung HF et al.; Previous studies have described a partially defined system for the DNA-directed in vitro synthesis of beta-galactosidase (Kung, H.F., Redfield, B., Treadwell, B.V., Eskin, B., Spears, C., and Weissbach, H . (1977) J . Biol . Chem . 252, 6889-6894) . An Ehrlich ascites extract was shown in these in vitro studies to acylate Escherichia coli tRNA with 13 amino acids, and the ascites extract was used in place of the corresponding 13 E . coli aminoacyl-tRNA synthetases . The present studies indicate that the ascites extract is supplying an additional protein factor, besides the aminoacyl-tRNA synthetases, that stimulates the DNA-directed synthesis of beta-galactosidase . The protein factor has been highly purified and may be functioning by protecting mRNA against degradation . In addition, NAD or T4 DNA ligase stimulates the synthesis of beta-galactosidase in the partially defined system.

J Biol Chem, 1979 Sep 10, 254(17), 8143 - 52
Proton magnetic resonance studies on Escherichia coli dihydrofolate reductase . Assignment of histidine C-2 protons in binary complexes with folates on the basis of the crystal structure with methotrexate and on chemical modifications; Poe M et al.; The effects of pH upon the C-2 resonances of the 5 histidine residues of Escherichia coli MB 1428 dihydrofolate reductase in binary complexes with methotrexate, aminopterin, folate, methopterin, and trimethoprim were studied by 300-MHz 1H nmr spectroscopy . Three of the five histidine residues, labeled 1, 2, and 3, exhibited similar pK' values and chemical shifts for their C-2 protons in the five binary complexes . One histidine, 4, was quite different in the folate complex and the last histidine, 5 was quite different in the trimethoprim complex . For all five binary complexes, each histidine had a pK' which was significantly different from the other 4 histidines of that complex . Titration of the binary methotrexate complex of a 5,5'-dithiobis(2-nitrobenzoate)-modified enzyme showed that 2 histidines were not perturbed by this modification of Cys 152, and that the alkaline form of histidine 2, the acid form of histidine 4, and, to a lesser extent, the acid form of histidine 3 were slightly perturbed . Titration of the binary methotrexate complex of a N-bromosuccinimide-modified enzyme demonstrated that this modification slightly affected all of the histidines and drastically affected histidine 5 . Histidines 3 and 5 of the binary methotrexate complex reacted rapidly with the histidine-specific reagent, ethoxyformic anhydride, while histidines 2 and 4 reacted at a moderate rate and histidine 1 reacted slowly if at all . The local electrostatic environments of the 5 histidine residues as deduced from the crystal structure of the binary complex of the enzyme with methotrexate (Matthews, D.A., Alden, R.A., Bolin, J.T., Freer, S.T., Hamlin, R., Xuong, N., Kraut, J., Poe, M., Williams, M.N., and Hoogsteen, K . (1977) Science 197, 594-597) were used as the basis for proposed assignments of the five histidine C-2 nmr resonances . The assignments were: 1, pK' 7.9 to 8.2, His 124; 2, pK' 7.2 to 7.4, His 141; 3, pK' 6.5 to 6.7, His 149; 4, pK' 5.7 to 6.3, His 114; and 5, pK' 5.2 to 5.9, His 45 . The effect of the chemical modifications upon the enzyme's histidine residues were consistent with the assignments, but no direct chemical evidence in support of the assignments was obtained . It was proposed that, since the crystallographic data provided consistent assignments of the histidine nmr data for both native and chemically modified enzyme, the local environment of each of the 5 histidine residues was similar in the crystal and in solution.

Vet Rec, 1979 Sep 8, 105(10), 228 - 30
Escherichia coli diarrhoea in pigs with or without the K88 receptor; Sellwood R; There was a high incidence of neonatal scours in 38 litters of pigs born at Compton in a four month period during 1978 . The most important cause of the disease was an enteropathogenic Escherichia coli strain which possessed the K88 antigen . The Compton herd has been bred to produce pigs of three genotypes with respect to the presence or absence of the intestinal receptor for the K88 antigen . These are homozygous dominants (SS) and heterozygotes (Ss) susceptible to infection by virulent K88-positive E coli, and homozygous recessives (ss) resistant to the disease . The highest incidence of diarrhoea was in the susceptible progeny of resistant dams and susceptible sires . There was no K88 associated diarrhoea in resistant progeny or in susceptible progeny of susceptible dams.

Biochemistry, 1979 Sep 4, 18(18), 4017 - 24
Nuclear magnetic resonance studies on the tertiary folding of transfer ribonucleic acid: assignment of the 7-methylguanosine resonance; Hurd RE et al.; Analysis of the low-field nuclear magnetic resonance (NMR) spectra of several class 1 D4V5 transfer ribonucleic acid (tRNA) species containing 7-methylguanosine in their variable loops reveals a set of six to seven tertiary base pair resonances, one of which is always located at ca . --13.4 ppm . Other tRNA species which do not contain 7-methyl-guanosine do not contain the tertiary resonance at --13.4 ppm . Chemical removal of 7-methylguanosine from several tRNAs containing the same dihydrouridine (DHU) helix sequence as yeast tRNAPhe results in the loss of the --13.4-ppm tertiary resonance . In the initiator methionine tRNA, which contains a different DHU helix sequence, the 7-methylguanosine hydrogen bond has been assigned at --14.55 ppm by chemical removal of this residue . In these experiments the aromatic C8H proton of 7-methylguanosine was also assigned (--9.1 ppm) . The unexpectedly low-field position of the 7-methylguanosine resonance is explained by the deshielding effect of the delocalized positive charge in this nucleoside.

Biochemistry, 1979 Sep 4, 18(18), 4012 - 7
Paramagnetic ion effects on the nuclear magnetic resonance spectrum of transfer ribonucleic acid: assignment of the 15--48 tertiary resonance; Hurd RE et al.; We have studied the effects of Co2+ and Mn2+ ions on the low-field nuclear magnetic resonance (NMR) spectra of pure class 1 transfer ribonucleic acid (tRNA) species . With 1.2 mM tRNA in the presence of 15 mM MgCl2 discrete paramagnetic effects were observed for Co2+ at concentrations in the range 0.02--0.1 mM and for Mn2+ in the range 0.002--0.01 mM, indicating fast exchange of these cations with tRNA . Both of these cations paramagnetically relax the s4U8--A14 resonance as well as other resonances from proximal base pairs . The Co2+ site appears to be the same site on G15 which was observed crystallographically {Jack, A., Ladner, J . E., Rhodes, D., Brown, R . S., & Klug, A . (1977) J . Mol . Biol . 111, 315-328}; the initially occupied tight Mn2+ site is the cation site involving the phosphate of U8 . There are three base pairs within 10 A of both sites, namely, G15--C48, A14--s4U8, and C13--G22; this has led to the assignment of the G15--C48 and C13--G22 resonances in the NMR spectrum {Jack, A., Ladner, J . E., Rhodes, D., Brown, R . S., & Klug, A . (1977) J . Mol . Biol . 111, 315--328; Holbrook, S . R., Sussman, J . L., Warrant, R . W., Church, G . M., & Kim, Sung-Hou (1977) Nucleic Acids Res . 4, 2811--2820; Quigley, G . J., Teeter, M . M., & Rich, A . (1978) Proc . Natl . Acad . Sci . U.S.A . 75, 64--68}.

Biochemistry, 1979 Sep 4, 18(18), 4005 - 11
Nuclear magnetic resonance studies on transfer ribonucleic acid: assignment of AU tertiary resonances; Hurd RE et al.; The hydrogen-bonded ring NH nuclear magnetic resonance (NMR) spectra of several transfer ribonucleic acid (RNA) species have been examined with particular emphasis on the extreme low-field portion . Betwen --13.8 and --15 ppm there are two extra resonances which are not derived from cloverleaf base pairs . A combined approach involving undermodified tRNAs, chemical modification, and hairpin fragment studies has assigned the T54--A58 resonance at --14.3 ppm in yeast tRNAPhe and Escherichia coli tRNA1 Val., the U8--A14 resonance has been assigned at --14.3 ppm, and the s4U8--A14 resonance in bacterial tRNAs has been assigned at --14.9 ppm . The T54--A58 resonance shifts between --14.3 . and --13.8 ppm depending on the surrounding nucleotide sequence in the ribothymidine loop.

Biochemistry, 1979 Sep 4, 18(18), 3996 - 4005
Identification of tertiary base pair resonances in the nuclear magnetic resonance spectra of transfer ribonucleic acid; Reid BR et al.; The low-field hydrogen-bond ring NH proton nuclear magnetic resonance (NMR) spectra of several transfer ribonucleic acids (tRNAs) related to yeast tRNAPhe have been examined in detail . Several resonances are sensitive to magnesium ion and temperature, suggesting that they are derived from tertiary base pairs . These same resonances cannot be attributed to cloverleaf base pairs as shown by experimental assignment and ring current shift calculation of the secondary base pair resonances . The crystal structure of yeast tRNAPhe reveals at least six tertiary base pairs involving ring NH hydrogen bonds, which we conclude are responsible for the extra resonances observed in the low-field NMR spectrum . In several tRNAs with the same tertiary folding potential and dihydrouridine helix sequence as yeast tRNAPhe, the extra resonances from tertiary base pairs are observed at the same position in the spectrum.

Biochemistry, 1979 Sep 4, 18(18), 3927 - 33
Stereochemical course of phosphokinases . The use of adenosine {gamma-(S)-16O,17O,18O}triphosphate and the mechanistic consequences for the reactions catalyzed by glycerol kinase, hexokinase, pyruvate kinase, and acetate kinase; Blattler WA et al.; We report the synthesis of adenosine {gamma-(S)-16O,17O,18O}triphosphate, an isotopically labeled species of ATP that is chiral at the gamma-phosphoryl group, the configuration of which has been confirmed by independent stereochemical analysis . This molecule has been used as a substrate in the reactions catalyzed by glycerol kinase and by acetate kinase . The resulting samples of isotopically labeled sn-glycerol 3-phosphate and of acetyl phosphate have been used as substrates in the alkaline phosphatase mediated transfer of the chiral phosphoryl groups to (S)-propane-1,2-diol, whence the configuration at phosphorus has been determined {Abbott, S . J., Jones, S . R., Weinman, S . A., & Knowles, J . R . (1978) J . Am . Chem . Soc . 100, 2558} . It is shown that glycerol kinase and acetate kinase (and, by virtue of an earlier correlation, pyruvate kinase and hexokinase) proceed by pathways that result in inversion of the configuration at phosphorus . The sterochemical approach provides an access to the otherwise cryptic events that are involved in phosphoryl-group transfer within the ternary complexes of these kinases and their substrates.

Biochim Biophys Acta, 1979 Sep 3, 586(3), 537 - 44
Degradation of proteins in steady-state cultures of Escherichia coli; St John AC et al.; The degradation of proteins in Escherichia coli was investigated in cells grown under steady-state conditions in a glucose-limited chemostat . During the first 24 h, approximately 25% of pulse-labeled proteins were degraded and after 72 h up to 58% of the proteins were broken down . To examine the stability of subcellular components steady-state cultures were labeled with an initial pulse of {14C}leucine, 24 h were allowed for turnover of these proteins, and the cells were then labeled with a short pulse of {3H}leucine . By this double-label protocol, the labile proteins were preferentially labeled with {H}leucine and had high 3H/14C ratios, while the more stable proteins had lower 3//14C ratios . The 3/-labeled proteins were degraded approximately five times as rapidly as the 14C-labeled proteins in exponentially growing cells . The relative stability of subcellular fractions was determined by comparing their 3H/14C ratios to the ratio of the cells at harvest . The soluble fraction contained the most labile proteins, while the ribosomal and membrane fractions were at least as stable as the average cell protein.

Int J Biomed Comput, 1979 Sep, 10(5), 401 - 15
Numerical analysis of binding studies: a direct procedure avoiding the pitfalls of a Scatchard analysis of equilibrium data for unknown binding models; Peters F et al.; It is shown on theoretical grounds that the straightforward analysis of binding data according to Scatchard may lead to erroneous results, especially when more complicated binding schemes are involved . We have demonstrated this point by presenting Scatchard plots with slight variation of experimental parameters . These inherent difficulties of Scatchard analyses can be avoided by applying a direct procedure . We have developed a program, which compares the measured quantity and the theoretical value directly and which considers the following binding models: (i) independent equivalent binding of n ligands; (ii) independent unequivalent binding of 2 ligands; (iii) positive or negative cooperative binding of 2 ligands . Other binding schemes can easily be implemented . We have used this procedure for the evaluation of equilibrium data on the complex formation of tRNA-Tyr and tyrolyl tRNA synthetase from E . coli in terms of different binding models.

Aust Vet J, 1979 Sep, 55(9), 435 - 6
Vaccination of piglets against Escherichia coli enteritis; Husband AJ et al.; An immunisation procedure involving intraperitoneal followed by oral administration of a killed Escherichia coli vaccine was used to reduce losses associated with colibacillosis in young pigs reared under commercial conditions . Mortality was reduced in both the preweaning and postweaning period . The mortality rate among vaccinated piglets was half that of unvaccinated controls and by 3 weeks after weaning the total weight of pigs produced was 33% higher in the vaccinated group than in the control group.

Appl Environ Microbiol, 1979 Sep, 38(3), 431 - 5
Improved detection of coliforms and Escherichia coli in foods by a membrane filter method; Sharpe AN et al.; Analytical procedures based on filtration of homogenates through membrane filters, and particularly hydrophobic grid-membrane filters (HGMF), offer definite improvements in the enumeration of Escherichia coli and coliforms in foods . Whereas the counted specimen in pour plates may not usually be greater than 0.1 g, up to 1.0 g of ground beef, green beans, potato, cod, strawberries, or grapes could be filtered and counted on HGMF . Greatly improved limit of detection, reduced interference by noncoliforms, and complete removal of growth inhibitors such as polyphenols were demonstrated for HGMF, using violet red bile and mFC agars . In addition, counting on HGMF eliminated a false-positive reaction caused by sucrose in ice cream.

J Gen Virol, 1979 Sep, 44(3), 609 - 13
Is the DNA of virus T7 methylated?
Auer B, Gunthert U, Wagner EF, Schweiger M.
DNA modification of T7 wild type and of T7 M-mutants was studied by determining the percentage of 5-methylcytosine (5MC)/cytosine (C) and N6-aminopurine (6MA)/adenine (A) and by evaluating the plating efficiencies of restriction-sensitive T7 M-mutants on modifying and non-modifying host strains . Only 0.03% adenine and 0.02% cytosine were methylated in the DNA of T7 wild type as well as in T7 M-mutants, which was independent of the host DNA methylation (30- to 50-fold higher) . The restriction of T7 M-mutants, determined from the plating efficiencies, was not altered on modifying or non-modifying hosts . These results indicate that host-specific modification is blocked during T7 development and that this is not due to the M-protein.

Can J Genet Cytol, 1979 Sep, 21(3), 423 - 8
The influence of the PO1A1 mutation upon recombination in Escherichia coli K12; Glickman BW et al.; Genetic recombination in Escherichia coli is a highly regulated process involving multiple gene products . We have investigated the role of DNA polymerase I in this process by studying the effect of the po1A1 mutation upon DNA transfer and conjugation in otherwise isogenic suppressor-free strains of E . coli K-12 . It was found that the po1A1 mutation greatly reduces recombination in Hfr crosses (a factor of 20 in Pol+ x Po1A1 crosses and more than a factor of 100 in Po1A1 X Po1A1 crosses) . However, since the po1A1 mutation reduces the strains capacity to act as a recipient for an F-prime and the analysis of recombination transfer gradients revealed no differences between Po1+ and Po1- strains, it is concluded that DNA polymerase I probably affects the transfer and/or stability of donor DNA rather than the recombinational process itself.

Am J Vet Res, 1979 Sep, 40(9), 1285 - 7
Vaccination of the dam by the intramuscular or deep subcutaneous route to prevent neonatal calf enteric colibacillosis; Bagley CV et al.; Comparison of colostrum-induced immunities in calves was made by challenge exposure with Escherichia coli . These calves were delivered of cows which were vaccinated intramuscularly or deep subcutaneously (in the region of the mammary lymph nodes) with strain B44 E coli bacterin during the last trimester of pregnancy . The calf of each cow was allowed to nurse colostrum naturally after birth . Cows vaccinated by either route of administration were capable of providing increased resistance to their calves, via the colostrum, when compared with nonvaccinated cows.

Am J Vet Res, 1979 Sep, 40(9), 1223 - 6
Studies on the pathogenesis of Escherichia coli in the bursa of Fabricius (cloacal bursa) of the turkey; Hoskins JD et al.; Turkey poults were inoculated with avirulent or virulent strains of Escherichia coli by direct application to anal lips and were killed at postinoculation hours (PIH) 0.1, 2, 5, 10, 24, 48, 72, and 96 . Bursae of Fabricius (cloacal bursae) were collected, cultured, and examined by light, fluorescent, and electron microscopy . The virulent strain of E coli was not recovered from the bursae after PIH 24, although the avirulent strain was recovered up to PIH 96 . The E coli strains neither localized at nor associated with the bursal fold epithelium, passed through the follicular pad epithelium, nor caused cytopathologic changes in the lymphoid follicle . A mild catarrhal bursitis was observed at PIH 48 with the avirulent strain of E coli.

Acta Pathol Microbiol Scand {A}, 1979 Sep, 87A(5), 335 - 46
Hepatic changes in late canine endotoxin shock . A light and electron microscopic investigation; Nordstoga K et al.; The patho-morphological lesions in the liver in late stages of canine endotoxin shock were studied by light and electron microscopy . Light microscopic lesions included sinusoidal dilatations, with accumulation of red cells and leucocytes, varying damage of the sinusoidal lining, microthrombi and widening of the space of Disse . Necrotic foci were in some cases recognized within a varying number of lobuli, at times in the centrilobular areas . Electron microscopy revealed severe hepatocytic damage . These lesions included formation of blebs and other surface protrusions corresponding to cytoplasmic ecdysis . The resulting cytoplasmic fragments seemed frequently to enter the sinusoids . It is suggested that the severe disturbances observed in the proteolytic enzyme systems of plasma during endotoxin shock are influenced by the hepatic parenchymal changes observed.

Res Vet Sci, 1979 Sep, 27(2), 175 - 9
Increase in resistance to acute experimental coli-septicaemia in chicks given high levels of ferrous sulphate in the diet; Harry EG; The resistance of chicks to coli-septicaemia following injection of approximately 10(8) cells of Escherichia coli O78 was found to be appreciably increased in terms of mortality by the supplementation of their diet with 360 mg/kg or more of iron in the form of commercial hydrated ferrous sulphate . This was related to an increase in the plasma iron levels . The results suggest that increased resistance to infection could be partly achieved by correcting the hypoferraemia which has previously been shown to be produced in chickens by injections of E coli endotoxin lipopolysaccharide (LPS) . The results also showed that haematological disturbances in survivors of coli-septicaemia can persist for up to at least 30 days after infection.

Mol Gen Genet, 1979 Sep, 175(2), 231 - 3
Plasmid pSC101 replication in integratively suppressed cells requires dnaA function; Felton J et al.; Maintenance of plasmid pKC17, a derivative of plasmid pSC101, in E . coli requires a functional dnaA gene product . This was demonstrated by segregation experiments using an E . coli dnaA46 mutant, at various temperatures . Growth of this mutant at elevated temperature was allowed by the presence of a P2sig5 prophage . rpoB mutations, which suppress the temperature sensitivity of a dnaA46 mutant permit efficient maintenance of plasmid pKC17 at temperatures up to 40 degrees, conditions which normally inactivate the dnaA46 product.

Mol Gen Genet, 1979 Sep, 175(2), 121 - 7
Temperature dependent release of beta-beta' subunits of DNA dependent RNA polymerase from the folded chromosome of a dnaAts mutant of Escherichia coli; Eaton LC et al.; DNA-dependent RNA polymerase has been found to be preferentially released at 43 degrees C from the folded nucleoids of an E . coli dnaAts mutant when compared with the same nucleoids at 30 degrees C or with nucleoids of a dnaA+ strain at either 30 degrees or 43 degrees C . The polypeptides released are identical in molecular weight with those of the beta and beta' constituent polypeptides of the core enzyme of a known E . coli RNA polymerase . In addition, these polypeptides are precipitated by specific anti-RNA polymerase rabbit IgG . The implications of the interactions of RNA polymerase with the dnaA gene product are discussed.

Cell, 1979 Sep, 18(1), 61 - 71
Role of plasmid-coded RNA and ribonuclease III in plasmid DNA replication; Conrad SE et al.; An in vitro replication system has been used to study the control of DNA replication of the relaxed plasmids Col E1 and RSF1030 . An RNA transcript approximately 100 nucleotides long is synthesized during the in vitro DNA replication reaction . This RNA is synthesized approximately 450 bp away from the origin of replication . A small insertion in the coding sequence for the RNA made from Col E1 DNA leads to a larger RNA species and simultaneously to an increase in plasmid copy number . Revertants missing the specific insertion show shorter RNA transcripts and wild-type copy number . Although plasmids Col E1 and RSF1030 have no extensive sequence homology, the RNA synthesized during RSF1030 replication has almost the same mobility as the Col E1 RNA on polyacrylamide gels and hybridizes to the Col E1 origin region . Extracts prepared from mutants of Escherichia coli deficient in ribonuclease III do not replicate RSF1030 or Col E1 plasmids in vitro . When supplemented with homogeneous RNAase III, such extracts do support DNA replication on these templates, indicating that RNAase III is required for DNA replication . We propose that the 100 nucleotide RNA species is involved in regulating the initiation of DNA replication of these plasmids, and that RNAase III may be involved in processing this RNA.

Transfusion, 1979 Sep-Oct, 19(5), 558 - 61
Anti-Kell (K1) in idiopathic thrombocytopenic purpura; O'Brien M et al.; A transiently occurring anti-Kell antibody was observed in a 2 1/2-year-old child who had idiopathic thrombocytopenic purpura after recovery from an upper respiratory tract infection . The antibody was probably of the IgM class . There was no history of prior blood transfusion.

Proc Natl Acad Sci U S A, 1979 Sep, 76(9), 4507 - 10
On the evolution of accuracy and cost of proofreading tRNA aminoacylation; Savageau MA et al.; Aminoacylation of tRNA occurs with a high degree of accuracy in many cases because misacylated molecules are effectively proofread on the aminoacyl-tRNA synthetase by preferential hydrolysis . This hydrolysis releases an ATP equivalent of energy . An explicit relationship between cost of proofreading and the resulting degree of accuracy is presented . Experimental data from Escherichia coli for isoleucyl-tRNA synthetase proofreading valyl-tRNAIle are examined by means of this relationship, and a conjecture concerning the natural selection of accuracy and proofreading costs is put forth and tested . We have found the energy cost of accurate proofreading to be high . The minimum error, derived in previous theoretical studies, is never actually reached . Instead, higher values, determined by the balance between energy wasted in the cell as a consequence of error and the energy cost of proofreading, appear to be selected . The total cost of proofreading all types of tRNA aminoacylations is estimated to be approximately 2% of the energy required to synthesize a bacterial cell.

Proc Natl Acad Sci U S A, 1979 Sep, 76(9), 4400 - 4
Accessibility of guanine at position 44 in the invariant sequence 5'CCG44AAC3' of Escherichia coli 5S RNA to reaction with kethoxal; Larrinua I et al.; The reaction of Escherichia coli ribosomes with beta-ethoxy-alpha-ketobutyraldehyde (kethoxal) in a buffer containing 50--100 mM Tris.HCl at pH 7.4, 50 mM NH4Cl, and 5 mM Mg(OAc)2 readily released the 5S RNA from the ribosomes . When liberated, the 5S RNA is in a conformation such that position 44 is selectively reactive, in addition to the normally reactive quanines at positions 41 and 13 . Positions 41 and 13 have been previously shown to react in the 5S RNA in situ . The resulting new RNase T1 resistant oligonucleotides 5'CCG 44K AAUCAG51(3') and 5'ACCCCAUG 41KCCG 44KAACUCAG51(3') have been isolated and identified . These oligonucleotides have not been found in RNase T1 digests of 5S RNA that is not released from the ribosome . The guanine at position 44 is part of the invariant sequence 5'CCG44AAC3' which includes that portion of the molecule thought to interact with the invariant 5'GT psi C3' of tRNAs in the ribosomal A site . This invariant sequence of the 5S RNA may also form part of the binding site for protein L5.

Proc Natl Acad Sci U S A, 1979 Sep, 76(9), 4350 - 4
Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications; Towbin H et al.; A method has been devised for the electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets . The method results in quantitative transfer of ribosomal proteins from gels containing urea . For sodium dodecyl sulfate gels, the original band pattern was obtained with no loss of resolution, but the transfer was not quantitative . The method allows detection of proteins by autoradiography and is simpler than conventional procedures . The immobilized proteins were detectable by immunological procedures . All additional binding capacity on the nitrocellulose was blocked with excess protein; then a specific antibody was bound and, finally, a second antibody directed against the first antibody . The second antibody was either radioactively labeled or conjugated to fluorescein or to peroxidase . The specific protein was then detected by either autoradiography, under UV light, or by the peroxidase reaction product, respectively . In the latter case, as little as 100 pg of protein was clearly detectable . It is anticipated that the procedure will be applicable to analysis of a wide variety of proteins with specific reactions or ligands.

Mutat Res, 1979 Sep, 62(2), 227 - 37
MMS mutagenesis in strains of Escherichia coli carrying the R46 mutagenic enhancing plasmid: phenotypic analysis of Arg+ revertants; Todd PA et al.; Arg+ revertants of E . coli AB1157 and derivative strains were selected after MMS mutagenesis and subjected to a phenotypic analysis which permitted the partitioning of revertants into 4 classes . The distribution of these revertant classes was influenced by mutations affecting DNA-repair systems, mutagen treatment and revertant-selection methods . Introduction of the R46 plasmid into strains also affected this mutational specificity, and it was concluded that the plasmid's mutagenic enhancing effect does not merely augment the cellular error-prone capacity to repair MMS damage to DNA.

Mutat Res, 1979 Sep, 62(2), 213 - 20
The mutagenicity of nitrosopyrrolidine is related to its metabolism; Hecker LI et al.; Various cell fractions from rat liver were tested for their ability to convert nitrosopyrrolidine (NO-PYR) to products which were mutagenic to E . coli in liquid-incubation assays . Microsomes alone produced only a small number of tyr+ revertants, approximately 40/10(8) survivors), while the S100 supernatant produced none at all . However, the S8 Fraction or combinations of microsomes and the S100 supernatant, yielded 300-400 tyr+ revertants/10(8) survivors . Neither products of the microsomal, nor microsome + supernatant reactions were mutagenic in the absence or presence of cellular fractions . These results suggest that bacterial mutagens are formed during the microsomal metabolism of NO-PYR to 2-hydroxytetrahydrofuran by alpha-hydroxylation, but not during the metabolism of 2-hydroxytetrahydrofuran by the S100 supernatant enzymes . Possible roles of the supernatant enzymes in the formation of mutagenic intermediates during the initial alpha-hydroxylation of NO-PYR are discussed.

Mol Biol (Mosk), 1979 Sep-Oct, 13(5), 994 - 1000
{Chemical modification of the complex of tRNA Phe with phenylalanyl-tRNA synthetase from Escherichia coli}; Ankilova VN et al.; Alkylation of E . coli tRNAPhe, bound to the cognate synthetase was investigated . The alkylating reagent is a derivative of 2-chloroethylamine: 2',3'-O-{4(N-2-chloroethyl-N-methylamino)-benzylidene}-uridine-5'-methylphosphate . It was found that the enzyme protects from the reaction D-stem (guanosine G24) and the region of juxtaposition of acceptor stem and D-stem (S4U8 and C13) in the tRNAPhe.

Mol Biol (Mosk), 1979 Sep-Oct, 13(5), 965 - 82
{Internal structure of ribosomes using different types of emission}; Serdiuk IN; A review is made of the experimental results obtained by the author and co-workers on the study of the structural organization of the RNA and the protein in ribosomes by the method of joint use of light, X-ray and neutron scattering and by the method of contrast variation in neutron scattering . Two rules are formulated for the folding of the ribonucleoprotein strand in ribosomes: (1) in each ribosomal subparticle the RNA is concentrated predominantly closer to the center of the particle whereas the protein has a more peripherical localization; (2) the compact ("crystallic") packing of hydrated RNA helices is an essential feature of the nucleus (nuclei) organization of the particles . An analysis of the experimental data on neutron scattering by ribosomal proteins has been done and the globulin conformation in solution of some of these proteins has been established . The widespread concept according to which the majority of ribosomal proteins on the ribosome and in solution are enlongated expanded structures is disputed . It is suggested that all, or almost all, ribosomal proteins are usual globular proteins recognizing the specific sequence of RNA on the periphery of the particles, and , hence, that the formation of functional centrers on the ribosome is, in principle, analogous to the formation of functional centers of other complex proteins with a quaternary structure.

Mol Biol (Mosk), 1979 Sep-Oct, 13(5), 1077 - 84
{Transcription initiation: influence of ionic strength and actinomycin D on the kinetics of the open promoter complex formation between Escherichia coli RNA-polymerase and T7 DNA}; Zavriev SK et al.; A membrane filter assay has been devised to study the influence of ionic strength (0--150 mM NaCl) and actinomycin D on the kinetics of the open promoter complex formation between E . coli RNA-polymerase and {3H}DNA of T7 phage . The dependence of the complex formation rate upon the ionic strength is non-monotoneus with a maximum at 75--100 mM . The addition of one actinomycin molecule per 200 base pairs decreases the open promoter complex formation rate at ionic strength less than 100 mM . A promoter site selection model including liner diffusional selection is proposed which is in a good agreement with the experimental results obtained.

Mol Biol (Mosk), 1979 Sep-Oct, 13(5), 1012 - 20
{Complementarily addressed alkylation of Escherichia coli ribosomal RNA in complexes with particular conformation}; Karpova GG et al.; Among the number of complementary complexes of 23S RNA with alkylating derivatives of complementary oligonucleotides ((Ap)3-5 ARCl, (Cp)5CRCl and (Np)5NRCl) some complexes of peculiar conformation are observed . The rate constant of alkylaation within the peculiar complexes is four fold greater than that within the rest complexes . The latter are alkylated via an active intermediate that is formed in the first rate determining step by two step alkylation . Both individual 23S RNAs and one in the rRNA mixture are alkylated in the peculiar complexes . But 16S RNA is alkylated only by the two step alkylation . There is a single binding site in the rRNA that is alkylated with the alkylating derivatives of the definite nucleotide sequence at the definite base . The reagments with different sequences can alkylate different bases . The alkylating derivatives of hexa-nucleotide isoplits that are complementary to rRNA alkylate up to 45 +/- 10 complexes simultaneously . The conformation of these complexes enables alkylation with the higher rate constant mentioned above.

Mol Biol (Mosk), 1979 Sep-Oct, 13(5), 1001 - 11
{Influence of the structure of photoreactive ATP analogs on the affinity modification of phenylalanyl-tRNA synsthetase . Modification of the enzyme at two types of nucleotide sites}; Lavrik OI et al.; ATP gamma-(p-azidoanilidate) (1) and ATP gamma-(p-azidobenzyl)-methylanilidate (2) were shown to be competitive inhibitors for ATP and amino acid in tRNA aminoacylation catalyzed by E . coli MRE-600 phenylalanyl-tRNA synthetase (E.C.6.1.1.20) . Low concentration (10(-5)--10(-6) M) of either ATP, gamma-anilidate or GMP stimulates the aminoacylation of tRNA suggesting their interaction with some nucleotide binding sites of the enzyme other than catalytic ones . Covalent photobinding of (1) to the enzyme does not inhibit aminoacylation, nor does it prevent nucleotides from activating the enzyme . UV-irradiation of the synthetase in the presence of (2) results in complete inactivation of the enzyme which can be prevented by phenylalanine or phenylalanine-ATP to save 50% of the enzyme activity but not ATP and tRNA . The photobinding of (2) to the enzyme in the presence of phenylalanine and ATP removes the activation of the enzyme by nucleotides suggesting that both the catalytic and effector sites of the synthetase are blocked in the same manner by compound (2).

Infect Immun, 1979 Sep, 25(3), 978 - 85
Purification and partial characterization of heat-stable enterotoxin of enterotoxigenic Escherichia coli; Takeda Y et al.; Heat-stable enterotoxin was purified from a strain of enterotoxigenic Escherichia coli 53402 A-1 from human intestine . The cells were cultured in Casamino Acids-yeast extract-salts medium, and the purification procedure consisted of protamine sulfate treatment of the culture supernatant, ultrafiltration with an Amicon PM-10 membrane, diethylaminoethyl-cellulose column chromatography, hydroxyapatite column chromatography, Bio-Gel P-10 gel filtration, 90% ethanol extraction, and preparative polyacrylamide gel disc electrophoresis . About 300-fold purification was achieved, with a yield of about 12% . However, the homogeneity of the purified heat-stable enterotoxin was not rigorously demonstrated . The purified heat-stable enterotoxin had an absorption maximum at about 275 nm, and its isoelectric point was about 3.90 . The molecular weight of the purified heat-stable enterotoxin was ca . 4,000 by Sephadex G-100 gel filtration . The minimum effective dose of purified heat-stable enterotoxin was about 2.5 ng in the suckling mouse assay . The purified heat-stable enterotoxin gave a positive reaction in not only the suckling mouse assay but also the mouse intestinal loop test and the guinea pig skin permeability test.

Clin Gastroenterol, 1979 Sep, 8(3), 625 - 44
The role of Escherichia coli in gastroenteritis; Rowe B; Publication Types:

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