Biochim Biophys Acta, 1982 Jan 26, 696(1), 102 - 6 A comparison of the phage T4 gene 32 protein and Escherichia coli RNA polymerase binding sites on hamster papovavirus DNA; Vogel F et al.; Phage T4 gene 32 protein and Escherichia coli RNA polymerase were bound to hamster papovavirus DNA . The binding regions were identified by electron microscopy employing a protein-free spreading technique . After gene 32 protein treatment four denaturation regions could be mapped, at 0.04-0.12, 0.30-0.36, 0.50-0.60 and 0.75-0.90 DNA map units, respectively, using the unique BamHI cleavage site as zero point . Eight RNA polymerase binding sites can be found which are localized at positions 0.05; 0.11; 0.18; 0.31; 0.57; 0.66; 0.76 and 0.82 . A comparison of the RNA polymerase binding sites with the gene 32 protein denaturation pattern reveals a correspondence of six of eight polymerase binding sites with (A+T)-rich regions within the hamster papovavirus genome. J Biol Chem, 1982 Jan 25, 257(2), 626 - 32 L-Aspartate oxidase, a newly discovered enzyme of Escherichia coli, is the B protein of quinolinate synthetase; Nasu S et al.; In Escherichia coli, quinolinic acid, a precursor of NAD+, is synthesized from L-aspartate and dihydroxyacetone phosphate . This synthesis requires two enzymes, a FAD-containing "B protein" and an "A protein." The B protein has been purified 500-fold from E . coli cells . The enzyme behaves as an L-aspartate oxidase . In the absence of A protein, it converts L-aspartate to oxaloacetate . To our knowledge, no enzyme with this activity has been described previously . The enzyme displays some unusual properties . In its role as B protein in quinolinic acid synthetase, product formation (quinolinic acid) is linear with protein concentration; however, when it functions as an L-aspartate oxidase, product formation (oxaloacetate) is a parabolic function of protein concentration . The L-aspartate oxidase activity also shows marked substrate activation at substrate concentrations above 1.0 mM . The L-aspartate oxidase and B protein activities of the enzyme are inhibited by NAD+, which is competitive with FAD . The immediate reaction product of the enzyme has the same characteristics (rate of decay to oxaloacetate, and condensation with dihydroxyacetone phosphate to form quinolinate) as the unstable reaction product (iminoaspartate) formed from D-aspartate oxidase . A reaction mechanism for the A protein-catalyzed condensation of dihydroxyacetone phosphate and iminoaspartate to form quinolinate is presented. J Biol Chem, 1982 Jan 25, 257(2), 599 - 602 Biosynthesis of galactosyl-beta 1,3-N-acetylglucosamine; Sheares BT et al.; The biosynthesis of galactosyl-beta 1,3-N-acetylglucosamine has been demonstrated using membrane preparations from pig trachea . Unlike the UDP-galactose:2-acetamido-2-deoxy-D-glucose 4 beta-galactosyltransferase, which is inhibited by high levels of N-acetylglucosamine, the UDP-galactose:N-acetylglucosamine 3 beta-galactosyltransferase shows no inhibition at 200 mM N-acetylglucosamine . About 80% of the total disaccharide synthesized at 200 mM N-acetylglucosamine was base-labile suggesting the 1,3-linkage, alpha-Lactalbumin inhibits galactose incorporation into galactosyl-beta 1,4-N-acetylglucosamine but has little or no effect on the activity of the 1,3-galactosyltransferase . Escherichia coli beta-galactosidase readily hydrolyzed the base-stable product, but not the base-labile component . The apparent 1,3-linked disaccharide was reduced with NaBH4 and was isolated by Bio-Gel P-2 column chromatography . Methylation analysis by gas chromatography/mass spectrometry showed tetramethyl galactose and a 3-substituted N-acetylglucosaminitol . Neither the beta 1,4 nor the beta 1,3 disaccharide was hydrolyzed by green coffee bean alpha-galactosidase . Both disaccharides were readily hydrolyzed by bovine testes beta-galactosidase . This is the first report on the galactosyltransferase which catalyzes the synthesis of the galactosyl-beta 1,3-N-acetylglucosamine linkage such as found in the Type I chain of human blood group substances . A tissue survey in rats showed only rat intestine to have readily detectable UDP-galactose: N-acetylglucosamine 3 beta-galactosyltransferase activity . The intestinal membrane fraction like the tracheal enzyme catalyzes the synthesis of two disaccharides as judged by base treatment, and these appear to be the beta 1,3 and beta 1,4 isomers of galactosyl-N-acetylglucosamine. Nucleic Acids Res, 1982 Jan 22, 10(2), 645 - 52 Specificity of acid RNase from HeLa cell lysosomes; Saha BK; The specificity of the lysosomal acid RNase {Saha, B.K., Graham, M.Y . and Schlessinger, D . (1979) . J . Biol . Chem . 5951-5957} has been determined by 5'-end labeling and sequencing gel electrophoresis of rRNA . The enzyme has a predilection for the dinucleotide sequence ...NU..., which is cleaved into ...Np and HOU... . Sequences AU and GU sequences is enhanced by the presence of adjacent purine residues . The specificity remains unaltered after partial denaturation of the RNA. Nucleic Acids Res, 1982 Jan 22, 10(2), 473 - 85 Is DNA unwound by the cyclic AMP receptor protein? Kolb A, Buc H. Superhelical pBR 322 derivatives have been relaxed by eukaryotic topoisomerase I in the presence or in the absence of E . coli cyclic AMP receptor protein (CRP) and of cyclic AMP (cAMP) . CRP alone, or cAMP alone do not affect the average linking number of the distribution of the relaxed topoisomers . Hence, they do not unwind the template . In the presence of cAMP, CRP induces a small unwinding . The extent of this unwinding is barely modified when the relaxation is carried out on a similar vector plasmid where the CRP binding site of the lac or of the gal operon has been inserted . Under these conditions, we checked that CRP occupies the lactose control site and that upon addition of RNA polymerase, the corresponding promoter is readily activated . These findings are difficult to reconcile with the proposal that activation of these promoters results from the binding of the CRP-cAMP complex to left-handed DNA sequences. Biochemistry, 1982 Jan 19, 21(2), 269 - 75 Functional groups at the catalytic site of BF1 adenosinetriphosphatase from Escherichia coli; Ting LP et al.; The rates of inactivation of BF1 adenosinetriphosphatase (BF1-ATPase) from Escherichia coli by 7-chloro-4-nitro-2,1,3-benzoxadiazole, 1-fluoro-2,4-dinitrobenzene, 2,4,6-trinitrobenzenesulfonate, phenylglyoxal, and N,N'-dicyclohexylcarbodiimide have been measured in the presence and absence of various concentrations of inorganic phosphate, ADP, ATP, or magnesium ion . Dissociation equilibrium constants and rate constants for the labeling reactions have been deduced from a quantitative treatment of the kinetic data . The results suggest that the essential Tyr, Lys, Arg, and Glu or Asp residues are probably located at the catalytic site of BF1-ATPase and that in addition to steric interference, the effect of charge interaction should also be considered in interpreting the kinetic data on the protection of BF1-ATPase by substrate molecules against inactivation by the above labeling reagents . Examination of the relative values of the rate constants for the labeling reactions in the presence and absence of inorganic phosphate, ADP, ATP, or magnesium ion, respectively, and the effect of NBD label on the rates of labeling of the essential guanidinium, amino, and carboxyl groups suggest that the arrangement of these four functional groups at the catalytic site of BF1 may be similar to that previously proposed for MF1-ATPase from bovine heart; namely, the essential amino group and the unusually reactive phenol group are probably located near the bound inorganic phosphate or the gamma-phosphate group of the bound ATP, the essential guanidinium group is probably located nearer to the alpha- or beta-phosphate group than to the gamma-phosphate group of the bound ATP or the bound inorganic phosphate, and the essential carboxylate group is probably complexed with a magnesium ion which it shares with the bound inorganic phosphate. Nucleic Acids Res, 1982 Jan 11, 10(1), 391 - 402 Key for protein coding sequences identification: computer analysis of codon strategy; Rodier F et al.; The signal qualifying an AUG or GUG as an initiator in mRNAs processed by E . coli ribosomes is not found to be a systematic, literal homology sequence . In contrast, stability analysis reveals that initiators always occur within nucleic acid domains of low stability, for which a high A/U content is observed . Since no aminoacid selection pressure can be detected at N-termini of the proteins, the A/U enrichment results from a biased usage of the code degeneracy . A computer analysis is presented which allows easy detection of the codon strategy . N-terminal codons carry rather systematically A or U in third position, which suggests a mechanism for translation initiation and helps to detect protein coding sequences in sequenced DNA. J Biol Chem, 1982 Jan 10, 257(1), 495 - 500 Mechanism of export of outer membrane lipoproteins through the cytoplasmic membrane in Escherichia coli . Binding of lipoprotein precursors to the peptidoglycan layer; Ichihara S et al.; Upon treatment of Escherichia coli cells with globomycin, precursors of Braun's lipoprotein, a peptidoglycan-associated lipoprotein (PAL) and several new species of lipoproteins accumulated in the cell envelope (Hussain, M . Ichihara, S., and Mizushima, S . (1980) J . Biol . Chem . 255, 3707-3012; and Ichihara, S., Hussain, M., and Mizushima, S . (1981) J . Biol . Chem . 256, 3125-3129) . The precursors of the Braun's lipoprotein and PAL thus accumulated were able to interact with the peptidoglycan layer . A considerable fraction of the precursor of Braun's lipoprotein was covalently bound to the peptidoglycan layer through its COOH-terminal lysine residue in the same manner as in the mature form . The manner of interaction of the precursor of PAL with the peptidoglycan layer was also the same as that of its mature form in which the central to COOH-terminal region of the lipoprotein is important for the interaction . Both precursors were localized in the cytoplasmic membrane when the outer and cytoplasmic membranes were separated after digestion by lysozyme of the peptidoglycan layer . When the cell envelope fraction was incubated, these precursors were chased to the corresponding mature forms . These results indicate that these proteins can be exported through the cytoplasmic membrane while they still retain the signal peptide that is most probably held in the cytoplasmic membrane. J Biol Chem, 1982 Jan 10, 257(1), 370 - 6 Role of superhelicity in homologous pairing of DNA molecules promoted by Escherichia coli recA protein; Shibata T et al.; In the presence of ATP and an excess of recA protein, superhelical closed circular DNA (form I DNA) and homologous single-stranded fragments paired to form D-loops in the early stage of incubation and dissociated during subsequent incubation . RecA protein that was not bound to single-stranded DNA ("free recA protein") was shown to be responsible for the dissociation of D-loops . Larger amount of free recA protein gave a lower final yield of D-loops . When the concentration of form I DNA was increased in the presence of a fixed amount of single-stranded DNA, larger amounts of free recA protein were required to produce a certain extent of dissociation . When form I DNA, excess recA protein, and ATP were incubated without single-stranded DNA, or with heterologous single-stranded fragments before the addition of homologous single-stranded fragments, formation and subsequent dissociation of D-loops were observed as in the case when all components of the reaction were added from the start . Therefore, the dissociation of D-loops is a result of the stoichiometric interaction between free recA protein and form I DNA bearing D-loops . In the process of formation and dissociation of D-loops, form I DNA was converted to an inactive substrate without any apparent damage to the DNA . The concentration of free recA protein appeared to decrease during the reaction . These observations revealed that formation and dissociation of D-loops are sequential reactions when form I DNA is the substrate and recA protein is present in excess . The dissociation of D-loops and the inactivation of form I DNA can be explained by a model in which recA protein cooperatively binds to form I DNA from the site of D-loop, resulting in stimulation of unidirectional unwinding of the double helix. J Biol Chem, 1982 Jan 10, 257(1), 80 - 7 Analysis of the Escherichia coli ribosome-ribosomal subunit equilibrium using pressure-induced dissociation; Infante AA et al.; Hydrostatic pressure can be used to perturb the ribosome-ribosomal subunit equilibrium . We have used glutaraldehyde fixation and subsequent sucrose gradient analysis to determine the equilibrium concentrations of Escherichia coli 70 S, 50 S, and 30 S particles at pressures from 1 to 1400 atm . This method is shown to be sufficiently rapid and free of interfering ribosomal aggregation artifacts when performed at Mg2+ concentrations below 8 mM . We show directly that the E . coli ribosome is in equilibrium with its subunits and that the pressure-sensitive reaction is appropriately described by the expression: In Kp = ln K0 + (P delta V/RT), where Kp and K0 are the equilibrium constants at pressure P and 1 atm, respectively, and delta V is the change in molecular volume that occurs during the reaction . The method provides values for K0 under different conditions, and the effects of Mg2+ ion can be readily ascertained . K0 and delta V were also estimated by a method of fitting computer-generated sucrose gradient profiles to experimental profiles . Determination of delta H0, delta S0, and delta V0 at 5 mM Mg2+ are presented . The results are discussed in the context of previous thermodynamic studies of the E . coli ribosome. J Biol Chem, 1982 Jan 10, 257(1), 289 - 97 Catalytic cycle of the biosynthetic reaction catalyzed by adenylylated glutamine synthetase from Escherichia coli; Rhee SG et al.; The covalently attached AMP moiety of adenylylated glutamine synthetase from Escherichia coli has been replaced by its fluorescent analog, 2-aza-1,N6-etheno-AMP (aza-epsilon-AMP) . The modified glutamine synthetase (aza-epsilon-GS) exhibits divalent cation requirement (Mn2+, rather than Mg2+), pH profile, Vmax, and Km similar to those of naturally adenylylated glutamine synthetase . Whereas naturally adenylylated glutamine synthetase exhibits only negligible fluorescence changes upon the binding of substrates, aza-epsilon-GS exhibits large fluorescence changes . The fluorescence changes have been used by means of a stopped flow technique to reveal the involvement of five fluorometrically distinct intermediates in the catalytic cycle for the biosynthesis of glutamine catalyzed by the adenylylated glutamine synthetase . The mechanism is very similar to that previously established for the unadenylylated enzyme, using intrinsic tryptophan fluorescence . Substrates bind via a rapid equilibrium random mechanism, but the reaction proceeds in a stepwise manner . The formation of an enzyme-bound intermediate (probably gamma-glutamyl phosphate + ADP) from ATP and L-glutamate is the rate-limiting step, with the subsequent reaction of the enzyme-bound intermediate occurring very rapidly . The success in elucidating this complex mechanism is due largely to the vastly different amplitudes of the fluorescence changes at the two excitation maxima (300 nm and 360 nm) of the aza-epsilon-AMP moiety which accompany the formation of the various intermediates. Biochemistry, 1982 Jan 5, 21(1), 96 - 102 Raman spectral evidence for a mu-oxo bridge in the binuclear iron center of ribonucleotide reductase; Sjoberg BM et al.; The Raman spectrum of the B2 subunit of Escherichia coli ribonucleotide reductase shows a peak at 496 cm-1 that appears to be in resonance with the 370-nm electronic transition of the binuclear iron center in both the native and radical-free forms of the protein . Exposure of the protein to H218O causes the peak to shift to 481 cm-1, indicating that the vibrational mode is due to an Fe-O moiety in which the oxygen can exchange with solvent . The rate of oxygen exchange (kobsd = 8.3 x 10-4 s-1) is consistent with a mu-oxo-bridged structure . Protonation of the oxygen is unlikely since the Fe-O vibration fails to shift to lower frequency in D2O . Instead, there is a gradual increase in the vibrational frequency with time to a maximum value of 502 cm-1 after 3 h in 70% with time to a maximum value of 602 cm-1 after 3 h in 70% D2O . Apparently, the deuteration of successive protein functional groups causes a slight alteration in the structure of the binuclear iron center . The resonance Raman characteristics of the Fe-O-Fe group in protein B2 are similar to those previously reported for the mu-oxo-bridged binuclear iron center in hemerythrin . A further similarity between the two proteins is the high degree of alpha-helical content . Circular dichroism measurements place this value at approximately 60% for the B2 subunit of ribonucleotide reductase. Biochemistry, 1982 Jan 5, 21(1), 189 - 95 Adenylate kinase of Escherichia coli: evidence for a functional interaction in phospholipid synthesis; Goelz SE et al.; Previous genetic and biochemical experiments have suggested that the adenylate kinase of Escherichia coli may be directly involved in phospholipid synthesis through formation of a complex with sn-glycerol-3-phosphate acyltransferase, the membrane-bound enzyme that catalyzes the first step in phospholipid synthesis . In this paper we report direct experiments to test this hypothesis . A mutation within the adenylate kinase structural gene is described that results in a temperature-sensitive phospholipid synthesis (assayed in vivo) and a temperature-sensitive acyltransferase . The adenylate kinase activity of this strain is only minimally altered either in vitro or {as assayed by adenosine 5'-triphosphate (ATP) levels} in vivo . This result demonstrates that the inhibition of phospholipid synthesis is not the result of reduced ATP levels . We report the purification of E . coli adenylate kinase to homogeneity; and find that the addition of homogeneous wild-type adenylate kinase to membranes containing a mutationally altered temperature-sensitive acyltransferase results in thermal stabilization of the acyltransferase activity . Ovalbumin has no such protective effect . Purified E . coli inner membranes contain several proteins that are precipitated by addition of anti adenylate kinase antibody to detergent-solubilized membranes. Lancet, 1982 Jan 2, 1(8262), 18 - 20 Hepatic encephalopathy and the gamma-aminobutyric-acid neurotransmitter system; Schafer DF et al.; gamma-Aminobutyric acid (GABA), the principal inhibitory neurotransmitter of the mammalian brain, is synthesised by gut bacteria . In a rabbit model the development of hepatic encephalopathy was associated with increased levels of GABA in plasma, increased permeability of the blood-brain barrier, increased numbers of binding-sites for GABA and benzodiazepines in the brain, and a pattern of neural activity similar to that induced by drugs which activate the GABA neurotransmitter system . It is postulated that in liver failure gut-derived GABA passes through a permeable blood-brain barrier and induces its own receptors in the brain, that gut-derived GABA contributes to the neural inhibition of hepatic encephalopathy, and that an increased number of drug-binding sites mediates enhanced sensitivity to barbiturates and benzodiazepines in liver failure. Tokai J Exp Clin Med, 1982, 7 Suppl, 157 - 64 The use of the laser light scattering for the molecular weight determination of membrane proteins in surfactants; Ishii JN et al.; A method is described for the determination of the molecular weight of the protein moiety of protein surfactant complexes using of low angle laser light (633 nm) scattering in combination with high performance porous silica gel chromatography, precision differential refractometry and differential UV absorption was described . The calibration curves in sodium dodecyl sulfate (SDS) and in a non-ionic surfactant, octaethyleneglycol dodecyl ether, using several reference proteins yielded linear lines . Molecular weight of porin oligomers and monomers, an intrinsic membrance protein that forms the permeability channel in the outer membrane of Escherichia coli, were calculated and were found to be 109,000 and 36,300, respectively in SDS and that of oligomers in octaethy leneglycol dodecyl ether was 114,200 . Similarly, the molecular weights of maltoporin oligomers and monomers, which form maltose-maltodextrin specific channels, appeared to be 148,500 and 48,200, respectively, in SDS and that of oligomers in octaethyleneglycol dodeclyl ether was 149,000. Leuk Res, 1982, 6(2), 183 - 95 A comparative study of the effectiveness of different mitogens for karyotypic analysis in chronic B cell leukemia; Katz RL et al.; In order best to study the karyotypic abnormalities of nine patients with chronic lymphocytic leukemia of B cell origin, we used a combination of T and/or B cell mitogens so as to achieve an optimal proliferative response . As assessed by DNA synthesis, and subsequent cytogenetic study, pokeweed mitogen (PWM) and protein A Sepharose (PROT A) appeared to hold promise as potent stimulators of neoplastic B lymphocytes . Lipopolysaccharide from E . coli (LPS) proved to be an ineffective mitogen . Phytohemagglutinin (PHA), while producing the highest stimulation indices by DNA assay, appeared to induce predominantly diploid metaphases . Pseudodiploid clonal abnormalities were noted in three out of nine patients, while another four patients showed random structural abnormalities, including translocations, which were indicative of damage . Presence of the A33 antigen, as determined by HLA typing, was noted in five out of nine patients . The increased frequency of this antigen in patients with chronic B cell leukemia is discussed. J Cell Biochem, 1982, 20(4), 381 - 92 Repair of O6-methyl-guanine residues in DNA takes place by a similar mechanism in extracts from HeLa cells, human liver, and rat liver; Myrnes B et al.; Extracts from HeLa S3 cells, human liver, and rat liver were found to contain an activity that transfers the methyl group from O6-methyl-guanine residues in DNA to a cysteine residue of an acceptor protein . The molecular weights of the acceptor proteins in HeLA cells and human liver are 24,000 +/- 1,000 and 23,000 +/- 1,000, respectively . Assuming that each acceptor molecule is used only once, the average number of acceptor molecules in HeLa cells was calculated to be about 50,000 . The extracts also contained 3-methyl-adenine-DNA glycosylase activity and 7-methyl-guanine-DNA glycosylase activity, although the latter activity was not detected in extracts from human liver in our assay system . Thus, the three major alkylation products resulting from the effect of methylating agents, such as N-methyl-N-nitroso urea, can all be repaired in animal cells . Pretreatment of HeLa cells with N-methyl-N'-nitro-N-nitrosoguanidine (0.1 micrograms/ml) strongly reduced the capacity of HeLa cell extracts to repair O6-methyl-guanine residues, while the activity of three DNA-N-glycosylases was essentially unaltered . This inactivation was not caused by a direct methylation of the enzyme by the carcinogen . The results demonstrate that the mechanism of repair of O6-methyl-guanine residues in DNA is strikingly similar in E coli and animal cells, including humans. Pol J Pharmacol Pharm, 1982, 34(1-3), 169 - 75 The plasma cation pattern in fever and sodium salicylate antipyresis; Hac EE; The effect of sodium salicylate at a dose of 200 and 1000 mg/kg, per os, on body temperature and plasma cation pattern was investigated in healthy rabbits and those infected with 1 microgram/kg iv of lipopolysaccharide Escherichia coli (LPS) . An increase in plasma Cu2+ and decrease in Fe2+ and Mg2+ concentration appeared to be the most important effect in LPS treated animals . Sodium salicylate in a dose-dependent manner attenuated the febrile response to LPS . Furthermore, this antipyretic antagonized the rise of Cu2+ concentration induced by pyrogen . Smaller increases of K+ and Mg2+ were observed during antipyresis than in the group of rabbits treated with sodium salicylate alone. Acta Chem Scand B, 1982, 36(10), 685 - 8 Antibodies to ornithine decarboxylase . Immunochemical cross-reactivity; Persson L; L-Ornithine decarboxylase was purified to apparent homogeneity from the kidneys of testosterone-treated mice . Antibodies to ornithine decarboxylase were raised in a rabbit using the purified enzyme . Ouchterlony double diffusion technique revealed a single precipitin line between the antiserum and purified mouse kidney ornithine decarboxylase . The antibodies inhibited ornithine decarboxylase from various tissues of mice and rats to the same extent, indicating a close immunological relationship . S-Adenosyl-L-methionine decarboxylase and L-histidine decarboxylase from mouse kidney as well as ornithine decarboxylase from Escherichia coli were unaffected by the antibodies. Rev Esp Fisiol, 1982, 38 Suppl, 141 - 6 {Regulation of the glyoxylic cycle: effect of the NADPH/NADP ratio}; Machado A; The utilization of two-carbon sources is carried out through the operation of the glyoxylic acid cycle . The cycle involves several Krebs cycle steps as well as two additional specific enzymes, isocitrate lyase and malate synthase . Kinetic data from the isocitrate transforming enzymes suggest that the flow of isocitrate through the glyoxylic acid cycle depends upon the inhibition of the isocitrate decarboxylating enzymes . Three different mechanisms have been proposed at present that could account for this inhibition: a) Inhibition by concerted action of oxalacetate and glyoxylate; b) NADP-linked isocitrate dehydrogenase phosphorilation in E . coli, and c) competitive inhibition by NADPH with respect to NADP . In the present case the variations of the NADPH/NADP ratio would be channeling the utilization of isocitrate into the glyoxylic acid cycle. Adv Shock Res, 1982, 8, 91 - 7 An evaluation of the functional implications of the intestinal mucosal lesions in shock; Haglund U et al.; Small intestinal mucosal lesions are reported in clinical shock and are commonly found in experimental shock . Experimental series in which shock is induced by regional intestinal ischemia or IV infusion of live Escherichia coli in cats or by graded intestinal vascular occlusion in rats are described . In all series mucosal damage was related to pronounced hypotension or mortality . In the cat models myocardial dysfunction was demonstrated in vivo by IV volume load and recording of changes in left ventricular filling pressure as related to cardiac performance . Following intestinal ischemia in cats and intestinal vascular obstruction in rats the intestinal venous plasma was found to contain cardiotoxic factors when tested in vitro . It is proposed that the development of small intestinal mucosa lesions in shock tends to further aggravate hypotension by causing intestinal release of cardioinhibitory material. J Cancer Res Clin Oncol, 1982, 104(1-2), 81 - 7 Tumor promoters specifically and reversibly disturb development and behavior of Caenorhabditis elegans; Miwa J et al.; The effect of phorbol ester tumor promoters on the development and behavior of a free-living soil nematode, Caenorhabditis elegans, was studied . When young developing C . elegans were grown on E . coli-seeded agar with low concentrations (0.1 microgram/ml) of 12-0-tetradecanoyl-phorbol-13-acetate or phorbol-12,13-didecanoate, their growth was arrested . These tumor promoters reduced the brood size when gravid adults were treated and caused uncoordinated movement in animals treated at any stage of development . The effects of these tumor promoters on nematode development and behavior were partially reversible . The nonpromoting derivatives phorbol and 4 alpha-phorbol-12,13-didecanoate showed no effect on the animals. Carcinogenesis, 1982, 3(8), 923 - 8 Excision of O6-methylguanine from DNA by human fibroblasts determined by a sensitive competition method; Teo IA et al.; A new, simple and relatively inexpensive assay for measuring O6-methylguanine (O6-MeG) in methylated DNA is described . This assay used the property of suicide inactivation of Escherichia coli methyltransferase . When crude extracts of methyltransferase are incubated with DNA containing O6-MeG, transfer of the methyl group to a cysteine residue on the protein occurs and the protein is subsequently inactivated . Each protein molecular has been shown to act only once . In our assay, methylated DNA is first incubated with a fixed amount of the extract . The O6-MeG present in this DNA proportionally inactivates a part of the methyltransferase activity . The remaining activity is then incubated with a fixed amount of O6-{3H}MeG substrate of known specific activity and precipitated with acid . Hydrolysis of the acid precipitable fraction releases the unaltered O6-{3H}MeG enabling the amount of O6-MeG present in the unknown sample to be calculated . This method enables the accurate measurement of as little as 0.1 pmol of O6-MeG in methylated DNA and compares favourably with current radiochemical and immunological techniques . We have used this assay to measure O6-MeG produced in the DNA of human fibroblasts treated with N-methyl-N'-nitro-N-nitrosoguanidine . We have also studied the kinetics of removal of this lesion . We confirm previous reports of a rapid repair system for the removal of O6-MeG from DNA by human fibroblasts. Immunobiology, 1982, 162(1), 15 - 27 Lactic dehydrogenase virus (LDV) impairs the antigen-presenting capacity of macrophages yet fails to affect their phagocytic activity; Isakov N et al.; The effect of acute infection of mice with lactic dehydrogenase virus (LDV) on two major functions of peritoneal macrophages was tested . Using a macrophage-dependent T cell proliferative assay to test the antigen-presenting capacity of LDV-infected macrophages we found that LDV impairs the capacity of antigen-presenting cells to trigger memory T lymphocytes . Endocytosis of antigen by LDV-infected macrophages was similar to that of uninfected cells . In addition, the proportion of intracellular antigen versus membrane-bound antigen in LDV-infected cells were similar to that observed in uninfected mice . It appears therefore, that the impaired immunogenic effect of LDV-infected macrophages results from reduced immunogenicity of the membrane-bound antigen . Testing the phagocytic activity of peritoneal macrophages we found that the uptake of radiolabeled antibody-coated sheep erythrocytes or bacteria (E . coli) by infected cells was similar to that by uninfected macrophages . In addition, LDV failed to affect the ability of peritoneal macrophages in a nitroblue tetrazolium reduction reaction which serves as an alternative parameter for measuring phagocytic activity . Our results support the assumption that LDV, which probably propagates in the cells of the reticuloendothelial system, impairs some of the immunogenic functions of macrophages and thereby affects macrophage-dependent immune responses. J Virol, 1982 Jan, 41(1), 51 - 65 Nucleotide sequence of a cloned woodchuck hepatitis virus genome: comparison with the hepatitis B virus sequence; Galibert F et al.; The complete nucleotide sequence of a woodchuck hepatitis virus genome cloned in Escherichia coli was determined by the method of Maxam and Gilbert . This sequence was found to be 3,308 nucleotides long . Potential ATG initiator triplets and nonsense codons were identified and used to locate regions with a substantial coding capacity . A striking similarity was observed between the organization of human hepatitis B virus and woodchuck hepatitis virus . Nucleotide sequences of these open regions in the woodchuck virus were compared with corresponding regions present in hepatitis B virus . This allowed the location of four viral genes on the L strand and indicated the absence of protein coded by the S strand . Evolution rates of the various parts of the genome as well as of the four different proteins coded by hepatitis B virus and woodchuck hepatitis virus were compared . These results indicated that: (i) the core protein has evolved slightly less rapidly than the other proteins; and (ii) when a region of DNA codes for two different proteins, there is less freedom for the DNA to evolve and, moreover, one of the proteins can evolve more rapidly than the other . A hairpin structure, very well conserved in the two genomes, was located in the only region devoid of coding function, suggesting the location of the origin of replication of the viral DNA. Cell, 1982 Jan, 28(1), 177 - 84 Filamentous phage pre-coat is an integral membrane protein: analysis by a new method of membrane preparation; Russel M et al.; We show, using a simple, rapid fractionation method, that the precursor to the filamentous phage major coat protein is an integral membrane protein . The method, which consists of treatment of Escherichia coli with 0.1 N NaOH followed by centrifugation, leaves a subset of inner and outer membrane proteins in the NaOH pellet . Most proteins partition into the NaOH pellet (membrane) or supernatant (cytoplasm and periplasm) in a manner consistent with their subcellular location as determined by more conventional techniques . We find no evidence for cytoplasmic filamentous phage pre-coat protein in either wild-type of mutant-infected cells . Our evidence suggests that a protein identified as "soluble procoat" by K . Ito, G . Mandell and W . Wickner may be the amber fragment of a different phage protein. J Reticuloendothel Soc, 1982 Jan, 31(1), 3 - 16 A microtechnique for studying chemiluminescence response of phagocytes using whole blood and its application to the evaluation of phagocytes in pregnancy; Selvaraj RJ et al.; Previous investigators have demonstrated that polymorphonuclear neutrophils exhibit intense chemiluminescence (CL) during phagocytosis and the CL response can be used to study the cellular and humoral aspects of the phagocytic process . A microtechnique that used 10 microliters of whole blood as a source of phagocytes was developed and used to measure the phagocytic CL response during pregnancy . Increased sensitivity was achieved by the use of a high concentration of luminol (0.5 mM), prepared by sonication, as a CL amplifier . The high intensity of CL produced with luminol permitted the use of a scintillation counter in the IN coincidence mode, avoiding the necessity of dark-adapting the counting vials and reagents and working under subdued red light . The CL response was dose dependent on the number of phagocytes and/or particles (polystyrene spherules, opsonized zymosan, and E coli) . The CL response was decreased by inhibitors that prevent particle uptake (iodoacetate and fluoride), inhibitors that prevent free-radical production (sodium benzoate and superoxide dismutase), and by inhibitors that inactivate myeloperoxidase (cyanide and azide) . Results suggested that the phagocytic CL response in our assay system was dependent on O2 activation followed by the activated O2 species reacting with myeloperoxidase and chloride . The new technique was used to demonstrate a progressive increase with gestation in the phagocytic CL response in pregnancy and a rapid decrease to normal values at 1 week postpartum. Adv Enzyme Regul, 1982, 20, 39 - 54 Identification of radiation-induced thymine derivatives in DNA; Teebor GW et al.; A methodology for the separation of radiation-induced thymine derivatives in DNA using high pressure liquid chromatography is presented . DNA was subjected to enzymatic hydrolysis yielding 2'-deoxyribonucleosides and the hydrolysate cochromatographed with marker compounds . Confirmation of the presence of derivatives was accomplished by chromatography on Sephadex LH-20 and microderivatization . The method separates free bases from nucleosides allowing for identification of spontaneously released bases or those released through the action of repair enzymes . The results indicate that most of the thymine derivatives formed in irradiated cellular DNA were the same as those found in DNA irradiated in solution . However, the major cellular derivative was not present in the latter . This derivative was identified as 5-hydroxymethyl-2'-deoxyuridine (HMdU) . HMdU has previously been shown to be cytotoxic to cells in culture and caused diarrhea and bone marrow failure when administered to mice . Thus, the presence of this radiation-induced thymine derivative in cellular DNA correlates with the known effects of ionizing radiation on cells and animals. Z Allg Mikrobiol, 1982, 22(3), 185 - 90 Bistability in the glucose and energy metabolism of ammonia-limited chemostat cultures of Escherichia coli ML 30; Muller PJ et al.; Recently bistability in the pyruvate production of ammonia-limited glucose-grown Escherichia coli ML 30 chemostat cultures was evidenced . The present investigation shows that the state of higher pyruvate production is connected with a lower glycogen content than in cells in the state of lower pyruvate production . The results support the view of a regulation of bistability on the step of pyruvate consumption by the citric acid cycle . Pronounced differences in energy formation in the two states of glucose bistability are discussed. Z Allg Mikrobiol, 1982, 22(3), 169 - 74 Fatty acid composition of lipids of Escherichia coli W 1655 F+ and its stable protoplast type L-form; Gumpert J et al.; The comparative fatty acid analysis of extractable and non-extractable lipids of Escherichia coli W 1655 F+ and its stable protoplast type L-form shows quantitative as well as qualitative differences . From 10 different fatty acids obtained 16:0, 17:0 and 18:0 are present at about the same quantities in the lipid fractions of the bacterial and L-form . The absence of larger amounts of 12:0, 14:0, and 14:beta OH fatty acids in non-extractable L-form lipids reflects the loss of the cell wall in L-form cells . 16:1 fatty acid was found in L-form lipids only . This qualitative difference and the 2-3 times higher content of 18:1 in L-form lipids and the 7 times lower content of cyc 19:0 in extractable lipids of the L-form may be interpreted as alterations characteristic for the changed composition of the cytoplasmic membrane in L-form cells. Microbios, 1982, 33(132), 81 - 92 Spontaneous mutation rates in continuous cultures: the effect of some environmental factors; Savva D; The rate of spontaneous mutation from tryptophan auxotrophy to prototrophy has been determined under different growth-limiting and environmental conditions in continuous cultures of Escherichia coli WP2 . The growth rate, aeration rate, pH and temperature were found to affect the rate of mutation . In glucose-limited cultures the mutation rate was found to be directly proportional to both the growth rate and the aeration rate . A temperature coefficient of 2 was observed and there was an optimum temperature and pH for mutation. Mol Gen Genet, 1982, 186(2), 298 - 300 Plasmid pKM101-mediated mutagenesis in Escherichia coli is inducible; Ciesla Z; A tif-1 umuC36 double mutant of Escherichia coli was constructed . It has been found that the umuC36 mutation prevents both increased spontaneous mutagenesis and enhanced reactivation of UV-irradiated lambda, phenomena normally observed in the tif-1 strain grown at 42 degrees C . When the plasmid pKM101 was introduced into tif-1 umuC36, an elevated spontaneous reversion rate of the his-4 mutation observed at 30 degrees C was further increased 6-fold at 42 degrees C . This was accompanied by a 10-fold increase in the ability of tif-1 umuC36 containing pKM101 and grown before infection at 42 degrees C to reactivate UV-irradiated lambda. Mol Gen Genet, 1982, 186(2), 240 - 6 New acetohydroxy acid synthase activity from mutational activation of a cryptic gene in Escherichia coli K-12; Robinson CL et al.; A mutation in an allele identified as ilvJ662 causes the expression of acetohydroxy acid synthase activity that is resistant to feedback inhibition by L-valine . the ilvJ662 allele was transduced as an unselected marker into a strain, CU1126 (ilvB, ilvHI), deficient in acetohydroxy acid synthase activity . The ilvJ662 allele appears to code for a new acetohydroxy acid synthase activity (acetohydroxy acid synthase IV), with physical, kinetic, and physiological properties distinct from the other three isozymes . The catalytic function of acetohydroxy acid synthase IV is highly stable at 37 degrees C in the presence or absence of ethylene glycol . However, sensitivity to feedback inhibition by valine is rapidly lost at 37 degrees C, but this property is somewhat stabilized by ethylene glycol . The rate of synthesis of acetohydroxy acid synthase IV is uniquely repressed by either leucine or isoleucine . These results suggest that the ilvJ+ allele is cryptic for acetohydroxy acid synthase IV, an isozyme distinct from the other acetohydroxy acid synthases. Mol Gen Genet, 1982, 186(2), 193 - 203 Detection and mapping of six miniF-encoded proteins by cloning analysis of dissected miniF segments; Komai N et al.; Various DNA subfragments were derived from miniF DNA by complete or partial PstI cleavage, and cloned in the plasmid vectors pBR322 or lambda dv1 . The recombinant plasmids obtained were introduced into an Escherichia coli minicell-producing strain, and the plasmid-coded proteins were radiolabeled and analyzed by gel electrophoresis . Six miniF-encoded proteins, larger than 11 000 daltons, were detected and their coding regions were mapped on the F plasmid genome . Three of them were assigned by taking into account the known nucleotide sequences (Murotsu et al . 1981; K . Yoshioka, personal communication) . The coding directions of some proteins were determined by inserting the lac promotor into one of the recombinant plasmids and analyzing the increase in production of the proteins . The coding direction of the five proteins analyzed so far was uniform . Comparison of these results with a functional map of miniF suggested possible roles of the proteins. Mol Gen Genet, 1982, 186(1), 66 - 70 Regulation of DNA synthesis and capacity for initiation in DNA temperature sensitive mutants of Escherichia coli . II . Requirements for acquisition and expression of initiation capacity; Eberle H et al.; This paper deals with the conditions that are necessary for the acquisition and expression of initiation potential in dnaA temperature sensitive mutants after they have been held for periods of time at nonpermissive temperature and then returned to permissive temperature in the presence of chloramphenicol . The following conditions were found to be essential: (1) 40-60 min at nonpermissive temperature during which time protein synthesis must occur; this period must be followed by (2) return to permissive temperature under which conditions active dnaA product is present, and (3) protein synthesis must be blocked during the first 10-20 min immediately after return to permissive temperature (when initiation takes place) . In order for expression of the initiation potential (4) the chloramphenicol must be removed to allow the progression of the replication forks which had been initiated to occur and (5) the recA+ phenotype appears to be required for acquisition or expression (or both) of the initiation potential. Mol Gen Genet, 1982, 186(1), 57 - 65 Regulation of DNA synthesis and capacity for initiation in DNA temperature sensitive mutants of Escherichia coli I . Reinitiation and chain elongation; Eberle H et al.; The capacity for initiation and subsequent chain elongation was examined in several DNA temperature sensitive mutants of Escherichia coli after the mutants had been held at nonpermissive temperature for approximately 1.5 generation equivalents and then returned to permissive temperature in the presence of chloramphenicol . The results obtained indicate that 4-5 sets of replication forks can be initiated after return to permissive temperature in the presence of chloramphenicol but the forks apparently become stalled and fail to complete chromosomal replication in the presence of chloramphenicol . In temperature reversible dnaA mutants, once the chloramphenicol is removed the forks appear to be able to resume replication at the nonpermissive temperature . The relationship between premature initiation and premature chain termination is discussed. Mol Gen Genet, 1982, 186(1), 153 - 5 Curing effect of clorobiocin on Escherichia coli plasmids; Cejka K et al.; Clorobiocin, an inhibitor of the gyrB subunit of DNA gyrase, was used for the curing of some Escherichia coli plasmids . Of the plasmids studied, ampicillin resistant R28K and a miniplasmid derived from R1drd-19 were effectively eliminated . We also succeeded in eliminating the ColA factor from E . coli strain B834(pBS103), which was resistant to the effect of currently used curing agents . Although a derivative of ColE1-pBR322 was effectively cured by clorobiocin, the ColE1 plasmid was resistant to its effect . The ColV plasmid determining virulence was effectively eliminated. Mol Gen Genet, 1982, 186(1), 1 - 9 The mechanism of untargeted mutagenesis in UV-irradiated yeast; Lawrence CW et al.; The SOS error-prone repair hypothesis proposes that untargeted and targeted mutations in E . coli both result from the inhibition of polymerase functions that normally maintain fidelity, and that this is a necessary precondition for translesion synthesis . Using mating experiments with excision deficient strains of Bakers' yeast, Saccharomyces cerevisiae, we find that up to 40% of cycl-91 revertants induced by UV are untargeted, showing that a reduction in fidelity is also found in irradiated cells of this organism . We are, however, unable to detect the induction or activation of any diffusible factor capable of inhibiting fidelity, and therefore suggest that untargeted and targeted mutations are the consequence of largely different processes . We propose that these observations are best explained in terms of a limited fidelity model . Untargeted mutations are thought to result from the limited capacity of processes which normally maintain fidelity, which are active during replication on both irradiated and unirradiated templates . Even moderate UV fluences saturate this capacity, leading to competition for the limited resource . Targeted mutations are believed to result from the limited, though far from negligible, capacity of lesions like pyrimidine dimers to form Watson-Crick base pairs. Genetika, 1982, 18(6), 947 - 55 {Mutation affecting the rate of RNA-polymerase beta beta'-subunit synthesis in Escherichia coli}; Sever IS et al.; As shown previously, rpoC1 temperature sensitive mutation affecting RNA polymerase beta' subunit, results in acceleration of beta beta' subunit synthesis at 42 degrees C . Also, it leads to the change in RNA polymerase sedimentation coefficient and to the reduction of RNA polymerase activity in vitro . According to the existing hypotheses, these properties of a mutant enzyme may be the cause of acceleration of synthesis of RNA polymerase in vitro . The opr1 mutation was found among Ts+ revertants of the Ts double mutant carrying rpoC1 and rif-r rpoB251 mutations . Reduction of the rate of beta beta' subunit synthesis caused by the opr1 mutation, is related to the structural changes of RNA polymerase itself . It has been shown, however, that the low activity in vitro and the altered sedimentation coefficient of the enzyme are not responsible for the accelerated synthesis of beta beta' subunits at 42 degrees C in the RpoC1 strains . Opr1 is a dominant mutation and it is located in the rpoBC region of the genetic map of Escherichia coli chromosome. Genetika, 1982, 18(6), 939 - 46 {Regulation of uridine phosphorylase gene activity in Escherichia coli K-12 . II . A study of the nature of the constitutive synthesis of uridine phosphorylase in the rho15(ts) genome}; Mironov AS; The nature of uridine phosphorylase constitutive synthesis was studied in the rho15(ts) mutant strain of Escherichia coli . The rho15 mutation causes the 8-10 fold increase in uridine phosphorylase activity under conditions of both induction of enzyme synthesis by cytidine and complete inhibition of the udpP promoter activity in the crp background . These data indicate that regulation of the udp gene which is controlled by the cytR repressor protein and by cyclic AMP -- CRP complex, is disturbed in the presence of the mutated rho factor . Introduction of the rho15 mutation into the udpP1 and udpP18 promoter mutants which are characterized by cytR and (or) CRP independent expression of the udp gene, leads to 2 fold reduction in uridine phosphorylase activity . From this, it may be concluded that the presence in bacteria of the rho15 mutation prevents transcription initiation from the intact udpP+ promoter and also leads to udpP1 and udpP18 mutant promoters inhibition . On the basis of these data, it is proposed that the effect of rho15 mutation on the udp gene expression is rather due to read-through transcription from an upstream highly efficient foreign promoter, than to relief of attenuation within the udp gene regulatory region . The uridine phosphorylase activity under control of this foreign promoter, i.e . in the rho15 genome, is reduced 2-3 fold when bacteria are grown on the minimal medium supplemented with L-methionine or casaamino acids . Based on these dat, it is suggested that increased udp gene expression in the rho15 background is due to read-through transcription, possibly, from the promoter of the neighbouring metE gene. Genetika, 1982, 18(6), 929 - 38 {Effect of mutations in the relC and spoT genes of the "stringent" control regulatory system on the gene expression of Escherichia coli K-12 nucleoside catabolism}; Brikun IA et al.; Influence of the relC and spoT mutations on the expression of catabolite-sensitive promoters of the deo operon (cytP0 and the udp gene (udpP) was studied by defining the activity of thymidine phosphorylase (the deoA gene) and uridine phosphorylase (the udp gene) under conditions of amino acid limitation on media with different carbon sources and in the cya genome . Under certain conditions, the activity of cytP and udpP promoters increased under the action of the spoT mutation, whereas the relC mutation suppressed this effect . These findings may indicate indirectly that the ppGpp accumulation in the spoT mutant cell was responsible for the effect . However, the relC mutation itself resulted in a decrease of the activity of neither the cytP, nor the udpP . On the contrary, under certain conditions, in the cytR constitutives for thymidine phosphorylase and only in the "double" deoR cytR constitutives for uridine phosphorylase, the relC caused an increased in the cytP and udpP activity . The deoR-dependent synthesis of uridine phosphorylase was found in the relC genome, i.e . the activity of this enzyme was increased about two fold under the influence of the deoR mutation . The data obtained are explained based on the following suggestion . The ppGpp accumulation in the spoT cells, on the one hand, can activate the catabolite sensitive cytP and udpP promoters, thus promoting the Rho-dependent termination prior to these promoters (Sukhodolets, Mironov, Linkova, 1981) and, on the other hand, it can inhibit expression of catabolite sensitive promoters as a result of a possible indirect effect of lowering the level of intracellular cAMP. Genetika, 1982, 18(6), 896 - 905 {New class of RP4 plasmid mutations inducing a mucoid-type of Escherichia coli K-12 cell growth}; Danilevich VN et al.; A new class of mutations is described which induce mucoid growth of Escherichia coli K-12 . Unlike classical capR and capS mutations, the mucoid phenotype of colonies of the cap forms obtained is determined by mutations in genomes of thermosensitive plasmids pEG1 and RP1-6Repts12, derivates of the RP1 Inc P1 Ap Tc Km factor and accompanied by a complete or partial loss of the thermosensitive character of maintenance . The morphological character induced by plasmids is not associated with changes in the sensitivity of bacteria to UV irradiation and is determined by superproduction of capsular polysaccharide differing in the chemical structure from colanic acid, a common capsular polysaccharide of E . coli K-12. Trans R Soc Trop Med Hyg, 1982, 76(2), 265 - 7 Enteropathogenic, enterotoxigenic and enteroinvasive Escherichia coli isolated from acute gastroenteritis patients in Lagos, Nigeria; Agbonlahor DE et al.; Enteropathogenic, enterotoxigenic and enteroinvasive Escherichia coli were isolated from 52 (4.8%) of 1,082 patients with acute gastroenteritis reporting at the Lagos University Teaching Hospital, Lagos, Nigeria between October 1979 and March, 1981 . Of the 52 strains of E . coli isolated, 35 (67.3%) were enteropathogenic, 12 (23.1%) were enterotoxigenic and five (9.6%) were enteroinvasive . E . coli 0111 (25.7%) was the most predominant among the serotypes of the "classical" enteropathogenic strains found in this study . Diarrhoea associated with enteropathogenic E . coli occurred only in children aged less than five years, whereas enterotoxigenic and enteroinvasive E . coli were found primarily in adults . The study has highlighted for the first time the important role that enterotoxigenic and enteroinvasive E . coli strains could play in acute diarrhoeal diseases in Lagos, Nigeria. Radiat Environ Biophys, 1982, 20(2), 79 - 87 Estimation of the contribution of ionization and excitation to the lethal effect of ionizing radiation; Petin VG et al.; A simple theoretical model is proposed for estimating the differential contribution of ionization and excitation to the lethal effect of ionizing radiation . Numerical results were obtained on the basis of published experimental data on the ability of bacterial cells Escherichia coli to undergo photoreactivation of radiation-induced damage . It was shown that inactivation by excitation may be highly significant for UV-hypersensitive cells capable of photoreactivation; inactivation by excitation increased with the energy of ionizing radiation and the volume of irradiated suspensions . The data are in qualitative agreement with the assumption of a possible contribution of the UV-component of Cerenkov radiation to the formation of excitations responsible for the lethal effect and the phenomenon of photoreactivation after ionizing radiation . Some predictions from the model are discussed. Mol Gen Genet, 1982, 185(3), 373 - 8 Biosynthesis of RNA polymerase in Escherichia coli . XII . Noncoordinate synthesis of core enzyme subunits after suppression of cell growth; Enami M et al.; In spite of the generally well-coordinated synthesis of RNA polymerase core enzyme subunits (alpha, beta and beta') in Escherichia coli, a situation was found during the growth transition from exponential to stationary phase in which this coordination was broken (the order of differential repression being alpha leads to beta' leads to beta; Kawakami et al . (1979) . The present study indicates that, during a certain period of the growth transition, twice as much beta subunit is synthesized as beta' subunit and the overproduced beta subunit accumulates as the assembly intermediate alpha 2 beta complex, which is rapidly and preferentially degraded . Two independent factors, i.e., carbon source down-shift and oxygen depletion, were examined separately for their influence on the coordinated regulation of the synthesis of RNA polymerase subunits . The depletion of glucose added as a sole carbon source was accompanied by repression of the synthesis of all core enzyme subunits, while under the same conditions the differential rate of sigma subunit synthesis increased . In contrast, the sudden ending of the oxygen supply resulted in specific repression of the synthesis of only beta and beta' subunits but not of sigma and alpha subunits . The latter result may be explained by the autogenous repression of the rpoBC genes by a temporal increase in the amount of unused cytoplasmic RNA polymerase. Carcinogenesis, 1982, 3(4), 415 - 21 Mutagenic activity of three isomeric N-nitroso-N-methylaminopyridines towards Escherichia coli K-12 in in vitro and animal-mediated assays; Kerklaan P et al.; Three isomeric nitrosomethylaminopyridines (2-NMPY, 3-NMPY, and 4-NMPY), of which only the 2-isomer exerts significant carcinogenic activity in rats, were tested in vitro and in the host-mediated assay for their activity to induce gene mutations in E . coli K-12 strain 343/113 . Two related carcinogenic nitrosamines were also tested, namely, nitrosodimethylamine (NDMA) and nitrosomethylaniline (NMA) . The in vitro mutagenicity tests were performed either without or in the presence of various fractions (S-9, microsomes, S-100) of rodent liver homogenates . The in vivo mutagenicity was determined in host-mediated assays, in which the indicator E . coli cells were recovered for the liver of treated animals . In experiments involving the S-9 liver fraction, only 2-NMPY among the nitrosomethylaminopyridines exerted a slight mutagenic effect . The low mutagenicity of this isomer, and the non-mutagenicity of the remaining 3- and 4-isomer could be partly explained in experiments involving microsomes and the S-100 fraction of rodent liver: 2-NMPY and 4-NMPY were activated to mutagenic factors by microsomes, but their mutagenic effect was completely abolished when S-100 was added . 3-NMPY, on the other hand, was directly mutagenic for E . coli but, again, its mutagenic potential was abolished when S-100 liver fraction was added to the incubation mixtures . NDMA was activated to mutagenic factors with both microsomes and S-9 fractions, whereas NMA could not be shown as mutagenically active under any of the present experimental conditions . It could be shown that the deactivating effect of the S-100 fraction was of nonenzymatic nature, and probably was due to the presence of thiol-containing "scavenger" molecules in this fraction . In the host-mediated assays, only the 2-isomer among the three exerted a mutagenic affect . The present results indicate that the three isomers investigated here are mutagenic either directly (3-NMPY) or upon microsomal activation (2-NMPY and 4-NMPY) . The non-carcinogenicity of 3-NMPY and 4-NMPY, and the non-mutagenicity of these compounds in host-mediated assays, is probably the result of very efficient deactivation by cytosolic (thiol-group-containing?)factors. Ann N Y Acad Sci, 1982, 389, 354 - 67 Hepatic metallothionein induction in inflammation; Sobocinski PZ et al.; Numerous chemically distinct phlogistic substances have been shown to induce hepatic metallothionein-Zn (MT) accumulation when administered to rats . These findings suggest that induction of this cysteine-rich metalloprotein occurs through the action of some common mediator(s) . Possible mediators include substances such as leukocytic endogenous mediator (LEM) and/or hormones known to influence hepatic protein synthesis . Studies were performed to examine further the mechanism(s) and potential mediators involved in endotoxin-induced MT accumulation . Additionally, the studies were performed to determine the possible involvement of genetic factors, which reportedly influence LEM production, in the induced MT response . Endotoxin (ET) was administered ip to rats and to EP-resistant, C3H/HeJ, and susceptible, C3Heb/FeJ, stains of mice . ET induced hypozincemia, hyperglucagonemia, and increased MT concentrations in rats . ET induced hypozincemia and MT accumulation to the same extent in both strains of mice . The induction of tolerance in rats to Zn depressing activity of ET also prevented hyperglucagonemia and additional accumulation of MT . Results suggest that glucagon, but not LEM, may be a common mediator in MT response during inflammatory stress. Ann N Y Acad Sci, 1982, 384, 417 - 34 The exchange of small molecules as a measure of normal and abnormal lung microvascular function; Harris TR et al.; Evidence exists for the utility of measures of small-molecule exchange in assessing the normal and abnormal transport status of the lung vasculature . The evidence for the usefulness of PS for 14C-urea is: 1 . PSu compares to other small molecules as would be expected from free-diffusion coefficients . 2 . The extraction of 14C-urea decreases with increase flow as would be expected of a diffusion-limited indicator . 3 . PSu is unaffected by moderate pressure increase, it increases when lymph protein flow indicated permeability increase, and it decreases when surface area is reduced . 4 . Lung injuries such as E . coli endotoxemia in sheep and ARDS in patients can both reduce PSu, presumably through surface area reduction, and increase PSu, through increased permeability . Two events that accompany clinically important vascular injury complicate the interpretation of lung MT curves . These events are surface area loss and heterogeneity of flow and transport properties in the lung . Additional work is needed to precisely measure these variables and assess their importance. Am J Vet Res, 1982 Jan, 43(1), 41 - 9 Scanning and transmission electron microscopic study of the small intestine of colostrum-fed calves infected with selected strains of Escherichia coli; Hadad JJ et al.; Colostrum-fed calves were fed milk replacer containing 10(11) enteropathogenic Escherichia coli (EEC) or nonenteropathogenic E coli (NEEC) . The NEEC failed to colonize the small intestine or to be associated with the intestinal wall . The EEC colonized the middle and caudal portions of the small intestine, and in these areas, 80% of the organisms were associated with the intestinal wall . Light, immunofluorescence, scanning, and transmission electron microscopic studies demonstrated a layer of EEC adherent to the mucosal surface of the jejunum and ileum of infected calves . Transmission electron microscopy revealed that each EEC was surrounded by an electron-lucent zone and that some organisms had dense fuzzy surface structures which resembled pili . In the staining with ruthenium red, the electron-lucent areas were occupied by thick capsular material which seemed to be in contact with the microvilli . In some areas of contact with EEC, the microvilli were elongated and projected into the intestinal lumen . Light microscopy demonstrated stunted, thickened, and fused villi with the lamina propria expanded by inflammatory infiltrate . Changes in the villous surface topography, such as denudation of the tips of the villi and exposure of the lamina propria into the lumen, were observed by light and scanning microscopies in samples taken after death of the calves, but not in adjacent samples removed from calves under general anesthesia. Am J Vet Res, 1982 Jan, 43(1), 140 - 4 Endotoxin-induced change in hemograms, plasma enzymes, and blood chemical values in anesthetized ponies: effects of flunixin meglumine; Fessler JF et al.; A study was made of flunixin meglumine (FM), an analgesic agent with antiprostaglandin activity, in the management of endotoxin-induced changes in ponies . Three groups of 5 ponies each were used: A--controls, B--nontreated ponies with endotoxin-induced shock, and C--ponies with endotoxin-induced shock treated with FM . Shock was induced in anesthetized ponies with IV injections of Escherichia coli endotoxin . Disruption of glucose homeostasis, insulin levels, hemograms, aerobic metabolism, and cell damage as indicated by plasma enzymes were observed . Treatment with FM (5 minutes) after shock was induced did not prevent general tissue damage as indicated by plasma enzymes, but separation of creatine phosphokinase into its 3 isoenzymes revealed a significant increase in the amount of the creatine phosphokinase isoenzyme bb in group B ponies, but not in FM-treated ponies (group C) . The source of this isoenzyme is believed to be brain tissue . Acidosis as indicated by lactic acid and venous pH was less in FM-treated ponies than in nontreated (group B) ponies . Blood glucose and insulin concentrations changed in both groups B and C (endotoxin-induced shock), but the patterns of change were different . The only effect of FM on hematologic values was a significant decrease in blood platelet counts . The results of these experiments indicate that FM improved cellular metabolism and reduced brain damage . These effects were believed to be the result of the maintenance of mean arterial blood pressure and enhanced perfusion of vital organs by preventing extensive vasodilation in the gastrointestinal tract. Acta Microbiol Acad Sci Hung, 1982, 29(1), 17 - 25 Drug-receptor interaction on plasmid elimination by phenothiazines and imipramine in Escherichia coli; Molnar J et al.; Plasmid elimination in Escherichia coli by a quaternary amine of chlorpromazine was demonstrated on different incompatibility groups of plasmid . The biological effect of the drug depends partly on the host bacteria and partly on the plasmid itself . Various receptor substrates such as adenosine, dopamine, histamine and norepinephrine do not alter the plasmid elimination by promethazine and imipramine . None of the known drug-receptors studied are involved in drug binding of the bacteria . The direct membrane action of imipramine and promethazine was demonstrated in electron microscopic studies and alterations in the bacterial membrane such as discontinuities, phase separation or rarely extensive lytic alterations were observed . Magnesium ions prevent the ultrastructural membrane alterations caused by imipramine and promethazine . There is some evidence that the drugs bind to two different receptor sites simultaneously on the plasmid replication site . The first and strongest binding has to be ionic through the side chain amino group, displacing the bivalent cations . In turn, the two aromatic rings of the fixed (ionically bound) drug molecules bind weakly through pi-electrons, hydrophobically or by a charge transfer complex . This weaker binding together with the ionic one are essential for biologic action and lead to the inhibition of plasmid replication . A schematic model of the effect of tricyclic psychotropic drugs on the bacterial membrane is proposed. Prikl Biokhim Mikrobiol, 1982 Jan-Feb, 18(1), 29 - 33 {Synthesis of aspartate decarboxylase in Escherichia coli strains}; Ruzgene AV et al.; The ability to synthesize intracellular aspartate decarboxylase was investigated in 19 E . coli strains, out of which strain AB 2472 proved most effective . The maximum accumulation of the enzyme was seen after 6-hour cultivation at pH 6.0, t = 37 degrees C and 4% DL-aspartate used as inducer . By thin-layer chromatography on silufol it was demonstrated that the product of aspartate decarboxylation was beta-alanine. Mol Gen Genet, 1982, 185(2), 369 - 71 Involvement of the nusB gene products in transcription of Escherichia coli tryptophan operon in vitro; Kuroki K et al.; Synthesis of trp mRNA in vitro directed by plasmid DNA carrying the entire trp operon was studied using crude protein extracts (S-100) from Escherichia coli strains carrying the nusA or nusB mutation or both . It was found that the levels of trp mRNA transcribed from the promoter-distal genes (trpCBA) relative to that from the promoter-proximal genes (trpED) was markedly lower with extracts from the nus- mutants than that from the nus+ strain . Kinetic experiments suggest that termination of RNA transcripts at intragenic transcriptional barriers is prevented by the nus gene products from allowing efficient expression of the operon. Mol Gen Genet, 1982, 185(2), 352 - 5 Damage to DNA induces expression of the ruv gene of Escherichia coli; Shurvinton CE et al.; Regulation of the ruv gene of E . coli was studied using phage Mud (Ap lac) to obtain a fusion of the lac genes to the ruv promoter . Beta-galactosidase synthesis in the ruv-lac fusion strain was induced by mitomycin C and other agents that damage DNA . The induction of beta-galactosidase could be altered by mutations either in lexA or recA from which it is concluded that ruv is regulated by lexA repressor . A possible function of ruv in promoting cell recovery following damage to DNA is discussed. Mol Gen Genet, 1982, 185(2), 344 - 51 Plasmid ColE1 conjugal mobility: the nature of bom, a region required in cis for transfer; Finnegan J et al.; Conjugal mobility of ColE1 and related plasmids is promoted by a wide range of conjugative plasmids . ColE1 produces trans-acting products and has a region required in cis (bom ; basis of mobility) for such mobility . Here we show that plasmid pBR322 contains a functional bom sequence located within a 141 bp HhaI fragment . This bom region is functional for conjugation promoted by several different conjugative plasmids and is highly conserved in ColE1 and contains nic the putative origin of transfer . The orientation and position of bom with respect to the ColE1 vegetative origin of replication can be changed without affecting the frequency of conjugal mobility promoted by R64drd11. Mol Gen Genet, 1982, 185(2), 334 - 8 Involvement of a gene of the chl E locus in the regulation of the nitrate reductase operon; Pascal MC et al.; A strain of E . coli carrying a Mudl insertion leading to chlorate resistance was found to lack nitrate reductase and formate dehydrogenase activities, but to synthesize b-type cytochrome constitutively . Introduction of this insertion mutation into a strain bearing a fusion between the nitrate reductase operon (chl C, chl I) and the lac structural genes resulted in the constitutive expression of the lac genes of this last fusion . Identical results were found when the Mudl was eliminated promoting a deletion in the original insertion site . This mutation was located midway between gal and aro A, at the Chl E locus . Study of a chl E strain already described revealed similar behaviour . Absence of nitrate reductase activity in these strains which constitutively express the structural genes of the nitrate reductase operon was tentatively attributed to the simultaneous lack of a cofactor of the nitrate reductase terminal enzyme, possibly cofactor Mo-X, and of a repressor of the operon. Mol Gen Genet, 1982, 185(2), 296 - 301 Proteolytic activities in yeast after UV irradiation . II . Variation in proteinase levels in mutants blocked in DNA-repair pathways; Schwencke J et al.; When the levels of three common yeast proteinases in exponentially growing cells of mutants blocked in different repair pathways are compared to that of isogenic wild-type cells, it can be seen that the level of proteinase B is enhanced in the mutants whereas the levels of leucin aminopeptidase (Leu.AP) and lysine aminopeptidase (Lys.AP) are similar in all strains . As in its corresponding wild type, the level of proteinase B activity is further enhanced after UV-irradiation in a mutant blocked in excision-repair (rad1-3) . In contrast, following the same treatment the level of proteinase B remains almost constant in a mutant blocked in a general error-prone repair system (rad6-1) and in a mutant defective in a more specific mutagenic repair pathway (pso2-1) . Cycloheximide, an inhibitor of protein synthesis, blocks the post-UV enhancement in proteinase B activity observed in rad1-3 indicating that, as in the wild-type cells, an inducible process is involved . The levels of Lys.AP and Leu.AP are, respectively, either unaffected or only moderately increased following UV-treatment of the repair defective mutants, as in wild-type strains . It is obvious that the induction of protease B activity following UV-treatment in Saccharomyces cannot be equated to the induction of the recA protein in Escherichia coli . However the correlation found between the block in mutagenic repair and the lack of UV-induction of protease B activity leads to questions on the possible role of certain protease activities in mutagenic repair in eucaryotic cells. Mol Gen Genet, 1982, 185(2), 290 - 5 Proteolytic activities in yeast after UV irradiation I . Variation in proteinase levels in repair proficient Rad+ strains; Schwencke J et al.; Specific proteolytic activities are known to be induced in Escherichia coli following irradiation . Consequently it seemed of interest to investigate whether variations in proteinase activities occur in yeast . Among the five most well known proteinases of Saccharomyces cerevisiae, we have found that proteinase B activity increases up to three times in wild-type RAD+ yeast cells after a dose of 50 Jm-2 of 254 nm ultraviolet light (40% survival) . Carboxypeptidase Y and aminopeptidase I (leucin aminopeptidase) activities were only moderately increased . Proteinase A activity was only slightly enhanced, while aminopeptidase II (lysin aminopeptidase) was unaffected in both RAD+ strains studied . The observed post UV-increase in proteinase B activity was inhibited by cycloheximide and was dose dependent . Increases in proteinase B levels were independent of the activation method used to destroy the proteinase B-inhibitor complex present in the crude yeast extracts . A standard method for comparison of the postirradiation levels among different proteinases, strains and methods of activation is presented. Mol Gen Genet, 1982, 185(2), 269 - 74 Kinetic suppression of translational errors by (p)ppGpp; Wagner EG et al.; The effect of (p)ppGpp on the accuracy of translation was studied in vitro using a poly(U)-programmed poly(Phe)-synthesizing system operating at incorporation rates and missense error frequencies close to the values obtained in vivo . Simulation of a relaxed phenotype in vitro was accomplished by limitation of the cognate aminoacyl-tRNA synthetase, while the noncognate aminoacyl-tRNA synthetase was included at saturating concentrations . This protocol yielded a Phe-tRNA-starved steady state system displaying the expected decrease in Phe polymerization rates accompanied by a drastic increase in relative Leu misincorporation errors . The use of purified enzymes permitted us to assay for the effects of the individual nucleotides ppGpp and ppGpp as well as their potential targets, the elongation factors Tu and G, upon the missense error rates . Our results support the conclusion that ppGpp reduces misincorporation in a starved in vitro system by preferentially inhibiting EF-Tu . The details of the proposed mechanism and their relevance to an in vivo situation are discussed. Mol Gen Genet, 1982, 185(2), 189 - 97 Characterization of long patch excision repair of DNA in ultraviolet-irradiated Escherichia coli: an inducible function under rec-lex control; Cooper PK; Excision repair in ultraviolet-irradiated wild-type Escherichia coli produces a bimodal distribution of repair patch sizes in the DNA . Approximately 99% of the repair events result in short patches of 20-30 nucleotides produced by a constitutive repair system . The remaining 1% result in patches which are at least 1,500 nucleotides in length . This long patch repair is shown to be a damage-inducible process under control of the rec-lex regulatory circuit . The kinetics of the two processes differ; short patch synthesis begins immediately after irradiation and is virtually completed prior to synthesis of the majority of the long patches . Long patch repair synthesis is a linear function of UV dose up to a plateau at 60 J/m2, and hence each long patch event is the consequence of a single UV-induced lesion . Long patch repair does not appear to be necessarily error-prone, since no alteration in repair synthesis occurs as a result of a mutation umuC- which renders cells nonmutable by UV . Evidence is presented suggesting that DNA polymerase I is responsible for both long and short patch synthesis in wild type cells under inducing conditions . In the absence of polymerase I the constitutive patch size averages 80-90 nucleotides, and this distribution is unchanged by induction. Int Arch Allergy Appl Immunol, 1982, 68(3), 226 - 32 Characterization and mitogenesis of feline lymphocyte populations; Rojko JL et al.; Feline lymphocyte populations from blood, spleen, lymph node, thymus and bone marrow were examined for the following markers: rosette formation with guinea pig erythrocytes (GPE-T cells); surface feline thymocyte antigen (T cells); surface immunoglobulin (B cells); cytoplasmic immunoglobulin (preB cells, plasma cells); receptors for the Fc portion of IgG (FcyR-positive T and B cells), and the third component of complement (CR-positive cells - primarily B cells) . The blastogenic responses of feline lymphocytes from peripheral blood, spleen, lymph node (LN), thymus and marrow were investigated using the following mitogens: Escherichia coli lipopolysaccharide (LPS), dextran sulfate (DxS), concanavalin A (conA), phytohemagglutinin (PHA) and pokeweed mitogen (PWM) . Feline T lymphocytes identified by rosette formation with GPE and surface thymocyte antigen were present in thymus, spleen, LN, blood and, rarely, in marrow . T cell subsets, but not B cell subsets, were differentiated according to mitogen activation . Cells responding to PHA were immature, nonrecirculating cells, which were most strongly activated in thymus {stimulation index (SI) = 12}, lymph node (SI = 11) and spleen (SI = 6) . PWM-responsive cells were relatively mature, recirculating lymphocytes of widespread distribution and blastogenesis was greater in spleen (SI = 36) and LN (SI = 29), followed by thymus (SI = 23) and blood (SI = 15) . Con A was a potent mitogen for cells of spleen (SI = 113), blood (SI = 80) and LN (SI = 77), but not thymus (SI = 7), suggesting that the con-A-inducible cell was a mature, recirculating, postthymic cell . Optimal mitogenic response to the B cell mitogen, LPS, was dependent upon increased cell concentrations (3 x 10(5) versus 1 x 10(5) per microtiter well) and increased incubation time (5 days versus 3 days) . Surface IgG- and IgM-bearing lymphocytes and CR-bearing cells from spleen and blood were stimulated preferentially . DxS was moderately mitogenic for CR-bearing lymphocytes in spleen (SI = 4), LN (SI = 3) and blood (SI = 3), but not marrow (SI = 1). Folia Microbiol (Praha), 1982, 27(2), 138 - 41 A rapid and economic method for estimation of the number of plasmid copies in Escherichia coli cells; Hochmannova J et al.; An economic method for a rapid estimation of the number of copies of plasmid R6K delta 1 in E . coli cells using lysis of the cells directly on the agarose gel and electrophoretic separation of radioactively labelled plasmid and chromosomal DNA's is described . The method, particularly useful for screening purposes, permits detection of both the CCC and OC forms of plasmids of molar mass 2-150 Mg/mol and it can be applied to other bacterial systems. Circ Shock, 1982, 9(2), 99 - 106 Variation in toxicity of Escherichia coli endotoxin after treatment with perfluorated blood substitutes in mice; Lutz J et al.; Treatment with perfluorochemicals (PFCs) shows a temporary decrease in phagocytic activity as measured by carbon clearance . The importance of this effect was checked by investigating the lethality after administrations of PFCs and Escherichia coli endotoxin in mice (NMRI strain) . When endotoxin was applied simultaneously with PFC (4.4 g/kg body weight, a dose which could compensate a loss of a third of blood volume) the lethality rose 7.8-fold . If the challenge with endotoxin occurred later than 12 h after PFC injection, the increase of lethality was of a distinctly smaller degree . By means of pretreatment with various substances the increased lethality of endotoxin could be shifted in the direction of the control . C 48/80, aristolochic acid, and hydrocortisone were effective in this respect; zymosan remained ineffective . The results show a weakened resistance towards toxins from the intestinal tract under PFC administration; precaution in this regard should be taken during therapy with PFC. Antimicrob Agents Chemother, 1982 Jan, 21(1), 5 - 10 Mode of action of the biotin antimetabolites actithiazic acid and alpha-methyldethiobiotin; Eisenberg MA et al.; Actithiazic acid and alpha-methyldethiobiotin inhibited the conversion of dethiobiotin to biotin resting-cell suspensions of Escherichia coli . The concentrations which effected 50% inhibition were 0.45 and 1.1 microM for actithiazic acid and alpha-methyldethiobiotin, respectively . Cells grown in low concentrations of the two biotin antimetabolites showed derepression of the biotin A operon, as evidenced by the enhanced levels of the enzymes 7,8-diaminopelargonic acid aminotransferase and dethiobiotin synthetase . Derepression was not due to any direct regulatory effect of the antibiotics but was the consequence of the inhibition of the biotin synthetase enzyme; this inhibition prevented the intracellular concentration of biotin from reaching the levels required for normal regulation of the biotin A operon. Zh Nevropatol Psikhiatr Im S S Korsakova, 1982, 82(3), 9 - 17 {Current status of the problem of the treatment and prevention of hereditary diseases}; Davidenkova EF; The author demonstrates the development of S . N . Davidenkov's concepts concerning the problem of treating and preventing hereditary diseases in modern genetics . The results of research work carried out by the author and her colleagues are presented . A new direction in the treatment of hereditary diseases, that is, targeted delivery of microincapsulated macromolecules (enzymes) to the cells, as an alternative to enzymotherapy, is described, and the results attained in this field are presented . Prospects of the new direction are demonstrated . Problems of prophylaxis and, particularly, prenatal diagnosis of hereditary diseases are described. Trans R Soc Trop Med Hyg, 1982, 76(1), 4 - 7 Correlation between susceptibility to malaria and babesia parasites and to endotoxicity; Clark IA; Adult (185g) rats are about twice as sensitive to the harmful effects of injected endotoxin as are younger (65g) rats . This relationship correlates with an earlier report on the densities of Plasmodium berghei at which deaths occur in rats of these two age groups . Similarly lizards, which withstand very high parasitaemias of malaria parasites, are refractory to very large doses of endotoxin . This correlation appears to hold for malaria and babesiosis in all host species for which information is available, with man, for instance, very sensitive to these infections and to injected endotoxin . It is now realized that endotoxicity is not caused by the direct effects of endotoxin, but is the consequence of the release of a range of harmful soluble mediators, mainly from macrophages . Since the susceptibility of a host species to endotoxicity and to malaria and babesiosis correlate, and the illness produced in each case is very similar, these harmful mediators which cause endotoxicity are likely candidates for the origins of much of the pathology of malaria and babesiosis . This concept may also explain the relationship between parasite density and illness in these infections in man. Toxicon, 1982, 20(1), 223 - 8 Colicins: a minireview; Lazdunski C et al.; Colicin are toxins that kill specifically E . coli bacteria . These cells have both an outer and a cytoplasmic membrane . Thus, three steps can be distinguished in colicin action: a) the interaction with specific receptors located at the cell surface, b) the uptake through the outer and eventually through the inner membrane, c) the action of the cell target that leads to cell death . In this short review, an overlook of these three steps is given. Proc Natl Acad Sci U S A, 1982 Jan, 79(2), 515 - 9 Propagation of satellite phage P4 as a plasmid; Goldstein R et al.; Satellite phage P4 has two known options for propagation . In its lytic cycle, its regulatory functions can act in trans to alter the actions of a helper virus (P2), which then provides necessary gene products, including capsid proteins . P4 also can be propagated in the absence of a helper as a prophage, with distinct sites for integration within the Escherichia coli chromosome . We determined that a single spontaneous mutation (vir1) of phage P4 allows a third mode of propagation: as a plasmid (along with continued integration into the host chromosome) . Hence, the P4 regulatory element is capable of (i) temperate; (ii) lytic, helper-dependent; and (iii) plasmid modes of development . These findings emphasize the close relationship between defective viruses and plasmids. Proc Natl Acad Sci U S A, 1982 Jan, 79(2), 302 - 6 Are DNA precursors concentrated at replication sites? Mathews CK, Sinha NK. We have asked whether the effective concentrations of deoxyribonucleotide 5'-triphosphates (dNTPs) at sites of DNA replication in vivo might be higher than the concentrations of dNTPs averaged over the entire cell volume . The approach involved determination of the dependence of DNA replication rate upon thymidine triphosphate concentration, both in vivo and in vitro system that closely approximates the intracellular replication apparatus . In T4 phage-infected Escherichia coli maximal rates of DNA synthesis were attained with dTTP pools of approximately 1.2 x 10(5) molecules per cell, corresponding to an average intracellular concentration of about 65 microM . When DNA synthesis was measured in the T4 purified protein system {Sinha, N . K., Morris, C . F . & Alberts, B . M . (1980) J . Biol . Chem . 255 4290--4303}, maximal rates were observed at dTTP concentrations of 200--240 microM . This represents a minimal estimate, therefore, of dTTP concentration at replication sites and suggests that at least a 3- to 4-fold concentration gradient exists near these sites . We discuss why such concentration gradients might be needed and how they might be generated . We also discuss the implications of these results for understanding the relationship between intracellular dNTP pools and mutation rates . A by-product of our study was the finding that exogenous thymidine is used for T4 DNA synthesis in preference to endogenous pathways to thymidine nucleotides; at high thymidine concentrations in vivo the endogenous pathways can be completely bypassed. Proc Natl Acad Sci U S A, 1982 Jan, 79(2), 218 - 22 lac repressor-lac operator interaction: NMR observations; Nick H et al.; We show here the changes in the NMR spectra of the Escherichia coli lac repressor when bound to isolated lac operator DNA . The observations focus on the aromatic residues--four tyrosines and a single histidine--in the amino-terminal DNA binding domain of the lac repressor . There is a good correlation between chemical shift changes seen by 19F NMR when compared with 1 H NMR of otherwise identical repressor--DNA complexes . The results suggest that the tyrosines do not intercalate in the DNA . The NMR spectral changes with similarly sized DNA fragments, not containing the lac operator DNA sequence, are different . Thus, the amino-terminal domain of the lac repressor is independently capable of discriminating between lac operator and nonspecific DNA sequences . There can be two amino-terminal fragments per operator in the specific complex. Gene, 1982 Jan, 17(1), 1 - 8 Recombinant plasmids carrying the glutamate dehydrogenase structural gene from Escherichia coli K-12; Sanchez-Pescador R et al.; Plasmid pRSP1, isolated from the Escherichia coli gene bank of Clarke and Carbon (1975), has been shown to complement the gdh-1 mutation that affects the synthesis of glutamate dehydrogenase (GDH) in the E . coli strain PA340 . The GDH structural gene of E . coli is present on a 2.3-Md DNA fragment from the hybrid plasmid pRSP1 and certain of its derivatives . Polypeptides synthesized by minicells carrying some of these plasmids, enabled us to make a preliminary determination of the direction of transcription of the gdh gene on the cloned fragments. Can J Comp Med, 1982 Jan, 46(1), 21 - 6 The role of K antigens of enteropathogenic Escherichia coli in colonization of the small intestine of calves; Hadad JJ et al.; The colonizing and proliferating abilities of enterotoxigenic acapsular or K99- mutants of bovine enteropathogenic Escherichia coli strains were compared with those of their capsulated and K99+ parent strains in the small intestine of infected colostrum-fed calves . Calves infected with the enteropathogenic E . coli parent strains developed profuse diarrhea and severe dehydration . None of the calves which received the acapsular mutant developed diarrhea and one of three calves inoculated with the K99- enterotoxigenic mutant developed moderate diarrhea . The parent enteropathogenic E . coli strains colonized the middle and lower small intestine; in these areas a layer of specific immunofluorescence against the enteropathogenic E . coli covered most villi and 80% of the organisms were associated with the intestinal wall . The acapsular mutant strain failed to colonize the small intestine and fluorescent bacteria were not observed in any area of the small intestine . The K99- mutant proliferated to a lesser extent than did the K99+ parent strain in all areas of the small intestine but moderately colonized the lower small intestine where fluorescent bacteria were observed to cover parts of the intestinal villi. Bol Med Hosp Infant Mex, 1982 Jan, 39(1), 11 - 7 {Antigenic cross-reaction between neonatal intestinal mucosa and certain serotypes of Escherichia coli}; Carrillo J; In the soluble and insoluble fractions of three intestinal mucosa of neonates, a study was made of the contents of Kunin's (ECA) common heterogenous antigen, and of somatic antigens of different E . coli serotypes . In the three mucosas, evidence was found that a fraction capable of hindering the antiserum anti-014, (antiserum anti-ECA), does exist . It was also discovered that the three mucosas have a variable content of substances which hinder antiserums contrary to different somatic antigens of various E coli's serotypes . Furthermore, the soluble and insoluble fractions of the intestinal mucosas "combine' when they are preincubated with some of the crude lipopolysaccharides (LPS) of E . coli enteropathogens and non-enteropathogenes, according to the determining antigens be they divided into equal parts or not . This last phenomenon modifies, in variable degrees, the capacity of these fractions to hinder the antiserums contrary to the determinative equal parts with E . coli . Based on the above observations, the author proposes a hypothesis in order to explain the different behaviour, (pathogen and/or commensal), of a similar E . coli's serotype when it settles in the intestine of different people Ann Microbiol (Paris), 1982 Jan, 133A(1), 91 - 9 Genetic studies concerning the mechanism of secretion of the maltose-binding protein of Escherichia coli; Bassford PJ Jr; Strains of Escherichia coli have been isolated in which the malE-gene encoding the periplasmic maltose-binding protein has been used to the lacZ-gene encoding the cytoplasmic enzyme beta-galactosidase . Certain of these strains synthesize malE-lacZ hybrid proteins that retain beta-galactosidase enzyme activity . The unusual properties of these fusion strains, at variance with our original predictions, have provided us the means to initiate a detailed genetic analysis of the protein export process. Ann Microbiol (Paris), 1982 Jan, 133A(1), 71 - 5 Synthesis of mRNA of malB operons at specific stages in the cell cycle of Escherichia coli; Ohki M et al.; The mRNA synthesis of the malB operons was examined using synchronous cultures of Escherichia coli . mRNA of the malB operons were synthetized in cell cycle-specific manners different from the bulk mRNA synthesis . The synthesis occurred in two stages during a cell cycle, one in the middle of the cycle and the other at the time slightly before cell division . Identification of the species of mRNA revealed that the malK-lamB operon was preferably transcribed in the former stage of the cycle while a major fraction of mRNA of the malE-malF operon was synthesized in the later stage. Ann Microbiol (Paris), 1982 Jan, 133A(1), 49 - 53 Sequence studies on the maltose-binding protein of Escherichia coli; Fowler AV et al.; The amino terminal sequence of the maltose-binding protein as well as the leader region were reported earlier {2} . The amino acid composition of the protein indicated that the protein has no cysteine and very few methionine, arginine and histidine residues . In contrast, the residues of lysine, alanine and aspartic acid (or asparagine) account for about a third of the approximately 360 amino acid residues in the protein . Five cyanogen bromide peptides ranging in size from 10 to 154 residues have now been isolated by Sephadex G50 and G100 gel filtration . These five peptides account for the whole protein . Sequence determination of these fragments as well as of others has now been initiated. Ann Microbiol (Paris), 1982 Jan, 133A(1), 37 - 41 Structural investigations of outer membrane proteins from Escherichia coli; Garavito RM et al.; The receptor of phage lambda of Escherichia coli W3110, and matrix porin from E . coli BE have been crystallized . Porin occurs in two crystal forms whose packing arrangements are different, allowing the conclusion that crystal growth occurs from monodisperse protein-detergent complexes . The tetragonal form yields resolution to 2.9 A . The hexagonal form allows conclusive support for the hypothesis that a large fraction of the polypeptide is present in beta-pleated sheet structure with the strands nearly parallel to the normal of the membrane plane. Ann Microbiol (Paris), 1982 Jan, 133A(1), 199 - 204 Membrane potential stimulated binding of the maltose-binding protein to membrane vesicles of Escherichia coli; Richarme G et al.; We show in this study that radioactively labelled purified maltose-binding protein of Escherichia coli binds specifically to membrane vesicles, in the presence of maltose . When a potential is imposed across the membrane, the specific binding is increased, dependent on maltose, abolished in a mutant defective in the tar-gene product, one of the methyl-accepting chemotaxis proteins. Ann Microbiol (Paris), 1982 Jan, 133A(1), 181 - 9 Maltose transacetylase of Escherichia coli: a preliminary report; Freundlieb S et al.; Crude extracts of Escherichia coli K12 contain an enzyme that is able to transfer the acetyl group of acetyl-co-enzyme A to maltose (maltose transacetylase) . Half maximal acetylation occurs at about 20 microM acetyl-coenzyme A . Half maximal concentration of maltose has not been determined precisely, but it is clear that it exceeds 10 mM . The appearance of maltose transacetylase is not induced by growth on maltose . Mutants carrying a defect in the malT gene, the positive regulator for the well known malA and malB regions, exhibit elevated levels of maltose transacetylase . The gene coding for the enzyme is not known that mutant analysis demonstrated that it is not part of malA, malB or malT . In addition, it is clear that the enzyme is not identical with thiogalactoside transacetylase, the gene product of the lacA gene . Besides maltose, maltodextrins and thiomaltose are substrates for maltose transacetylase. Ann Microbiol (Paris), 1982 Jan, 133A(1), 171 - 80 Reconstitution of maltose transport in malB and malA mutants of Escherichia coli; Brass JM; Pretreatment of lamB cells for 3 h with 10 mM Tris, pH 7.2, containing 25 mM Ca++ resulted in a Ca++-induced shift of the apparent Km of the maltose transport system from about 100 microM to about 15 microM . In contrast to maltose transport in untreated cells, that of Ca++-treated lamB cells was inhibited by anti-MBP (maltose-binding protein) antibodies . The calcium-induced permeability increase of the outer membrane allowed reconstitution of maltose transport in a malE mutant upon exposure to shock fluid or purified MBP . The efficiency of reconstitution, as judged by the Km of the maltose transport system in reconstituted cells, was rather high (Km = 5 microM) . Vmax was around 20% of the wild-type . The rapid increase in maltose transport between 2' and 30' of incubation with shock fluid indicated that MBP readily entered the periplasm of Ca++-treated cells . Maltose transport continued for at least 1 h after washing the reconstituted cells . Surprisingly, Ca++ treatment also seemed to allow partial reconstitution of maltose transport in strain SF1701 malT::Tn10 after incubation with cell-free extracts of strain pop1740 malB,malTc. Ann Microbiol (Paris), 1982 Jan, 133A(1), 161 - 3 Maltose and maltodextrin transport in Escherichia coli; Wandersman C; Escherichia coli K12 strains producing reduced amounts of LamB protein (one tenth the wild type amount) grow normally on dextrins but transport maltose at a concentration of 1 microM at about one tenth the normal rate . Dex--lamB missense mutants were found as derivatives of these strains . These Dex- mutants had a structurally altered LamB protein in the outer membrane, impaired in its interaction with phages lambda and K10, inefficient in maltose transport at low concentration (10 microM and below) . The Dex- mutants still produced one tenth the wild type amount of the LamB protein as the parental Dex+ strains . Analysis of Dex+ revertants showed that the phenotype reverts to Dex+ when the altered LamB protein is made in wild type amounts . Even though they were Dex+, these revertants were still drastically altered in maltose transport at low concentration. Ann Microbiol (Paris), 1982 Jan, 133A(1), 153 - 9 The maltose-maltodextrin transport system of Escherichia coli; Shuman HA; The general features of the active transport system for maltose and maltodextrins are described . Two cytoplasmic membrane components have been identified with the aid of lacZ-gene fusions . One protein (MalF) is an integral membrane protein . The other protein (MalK) seems to be a peripheral membrane protein on the inner aspect of the membrane. Ann Microbiol (Paris), 1982 Jan, 133A(1), 145 - 51 Aspects of maltose transport in Escherichia coli: established facts and educated guesses; Boos W; The transport system can translocate maltose and maltodextrins (up to 7 glucose moieties) in chemically unmodified form against concentration gradients that can reach 1:10(5) . To overcome the problems of diffusion of substrate across the outer membrane at substrate concentrations below 0.1 mM, the receptor for phage lambda has to be present in the outer membrane . The facilitated diffusion via the lambda receptor is accomplished by its interaction with maltose-binding protein . The maltose-binding protein-substrate complex, but not free substrates is recognized at the cytoplasmic membrane . This implies that the maltose-binding protein is essential for substrate translocation and that the cytoplasmic membrane has no second maltodextrin recognition site . Substrate translocation through the cytoplasmic membrane is tightly coupled to energy consumption and unidirectionally inward . The energy source used for substrate accumulation is not the electrochemical potential of protons, but phosphate-bound energy, likely to be ATP . In mutants that are blocked in maltose metabolism, exit of maltose occurs in chemically modified form as acetylmaltose . It is energy-dependent, blocked by uncouplers of the proton-conductive type and is stimulated by energy sources . It is not mediated by any malB-dependent function . The membrane-bound components of the system may establish a non-specific pore that is triggered by its interaction with the maltose-binding protein bound to its substrate . After translocation of one molecule substrate the pore has to be re-energized, possibly by ATP hydrolysis. Ann Microbiol (Paris), 1982 Jan, 133A(1), 129 - 38 Co-translational insertion of envelope proteins: theoretical consideration and implications; Vos-Scheperkeuter GH et al.; In this paper we examine some of the quantitative consequences of co-translational insertion of outer membrane proteins (OMP) . Due to the linkage of OMP-synthesizing polysomes to the cell envelope, the whole machinery involved in the synthesis of OMP must necessarily be membrane-bound and dynamic . Implications of the model are discussed. Ann Microbiol (Paris), 1982 Jan, 133A(1), 123 - 7 Reconsidering the early steps of protein secretion; Hall MN et al.; We have reviewed a unique mutation affecting the hydrophilic segment of the lambda-receptor signal sequence . Considering the implications of this mutation, we have proposed a model depicting early steps of protein secretion . The salient, novel features of this model are as follows . 1) The model explicitly states that the LamB protein must initiate the export process to be synthesized . Commitment to synthesis occur subsequent to an interaction between the hydrophilic segment of the signal sequence and a membrane export site, the initial interaction between the nascent secreted protein and the membrane . Implicit in this concept is obligatory co-translational secretion of lambda receptor . 2) We suggest the existence of a "stop translation" sequence . The role of this sequence is to halt translation in order to allow sufficient time for the hydrophilic portion of the signal sequence to initiate export by interacting with a membrane receptor . 3) We suggest that at least part of the "stop translation" sequence is located down-stream from the signal sequence, after residue 15 of the mature LamB protein . 4) We further speculate, albeit in the absence of direct evidence, that the hydrophobic portion of the signal sequence may also be part of the "stop translation" sequence. Mol Biol (Mosk), 1982 Jan-Feb, 16(1), 94 - 7 {Effect of Escherichia coli mutation affecting the RNA polymerase sigma factor on phage T4 development}; Zograf IuN; The bacterial RNA polymerase sigma factor is necessary throughout T4 development . T4 can develop in the E . coli RpoD800 mutant cells only at permissive temperature . RNA synthesis in T4-infected mutant cells remains temperature-sensitive throughout infection as in uninfected mutant bacteria . This shows that bacterial sigma factor is necessary for all types of RNA synthesis in infected E . coli . The data obtained suggest also that active sigma factor is necessary for early, but not for late T4 DNA replication. Mol Biol (Mosk), 1982 Jan-Feb, 16(1), 35 - 46 {Contacts of Escherichia coli RNA polymerase subunits with nucleotides of lacUV5 promoter}; Chenchik AA et al.; We have localized contacts between DNA and subunits of E . coli RNA polymerase (of both holo and core enzymes) along lacUV5 promoter . In the complex with the holo enzyme the anti-sense strand of DNA makes contacts with beta' subunit at -47, -46, -30, -12, +1, +5, +7, +9; beta subunit at -30, -25, -23, -12, +11, +30 and delta subunit at -17, -5, -3 nucleotides, while the sense-strand of DNA makes contacts with beta' subunit at -22, -21, -9, -6, -4, +3, +4, +6, +17; beta subunit at +17, +25, +27, +34; and delta subunit at -35, -18 nucleotides . In the complex with the core enzyme the anti-sense strand of DNA makes contacts with beta'subunit at -47, -23, -5, -3, +5, +7, +9; beta subunit at -23, -16, +11, +30 nucleotides while the sense-strand of DNA makes contacts with beta' subunit at -20, -19, +3, +4, +6, +17; beta subunit at -36, -35, -34, -31, -29, +17, +25, +27, +34 nucleotides alpha subunits of the holo as well as the core enzyme show no contact with DNA in the conditions providing specific complex formation. Mol Biol (Mosk), 1982 Jan-Feb, 16(1), 177 - 82 {Plasmid proteins inhibiting the activity of K and E1 colicins}; Rekesh AN et al.; Plasmid proteins with m . w . of 14 000--15 000 were chromatographically isolated from lysates of E . coli cells containing plasmids ColK and ColE1 . These proteins can reversibly inhibit the killing activity of K and E1 colicine and appear to be the immunity proteins of ColK and ColE1 plasmids and provide the defence of colicinogenic cells from their own colicin . The immunity protein of the ColK plasmid acts both upon K colicin and E1 colicin and vice versa . Unlike E2, E3 colicins or CloDF13 cloacin, K and E1 colicins are extracted from cells in a free state and not in a complex with the immunity protein. Mol Biol (Mosk), 1982 Jan-Feb, 16(1), 156 - 9 {Kinetic determination of the non-specific constants for the binding of Escherichia coli RNA polymerase to T7 phage DNA}; Zavriev SK et al.; The kinetics of promoter complex formation of E . coli RNA polymerase with T7 phage DNA was studied under different ionic strengths at DNA concentrations 0.15, 1.5 and 20 microns/ml . Based on the results obtained the non-specific binding constants, Keq, and the promoter complex formation rate constants, kp, were estimated . Within ionic strength range 0 + 125 mM NaCl the Keq and kp vary from 5.10(6) to 9.10(5) M-1 and from 0.8 x 0.26 x 10(9) M-1 S-1, respectively . The results are discussed from the view point of the one-dimensional diffusion sliding of the enzyme along DNA in the process of phomoter site selection. J Cell Biochem, 1982, 18(2), 239 - 44 Regulation of lactose transport by the phosphoenolpyruvate-sugar phosphotransferase system in membrane vesicles of Escherichia coli; Dills SS et al.; Regulation of lactose uptake by the phosphoenolpyruvate-sugar phosphotransferase system (PTS) has been demonstrated in membrane vesicles of Escherichia coli strain ML 308-225 . Substrates of the phosphotransferase system inhibited D-lactate energized uptake of lactose but did not inhibit uptake of either L-alanine or L-proline . This inhibition was reversed by intravesicular (but not extravesicular) phosphoenolpyruvate . Lactose uptake was also inhibited by enzyme IIIglc preparations that were shocked into the vesicles, and this inhibition was reversed by phosphoenolpyruvate . Intravesicular HPr and enzyme I stimulated methyl alpha-glycoside uptake but did not inhibit or stimulate lactose accumulation . Vesicles maintained at 0 degree C for several days partially lost 1) the ability to take up lactose, 2) the ability to accumulate PTS substrates, and 3) PTS-mediated regulation . Phosphoenolpyruvate addition restored all of these activities . These results support a mechanism in which the relative proportions of phosphorylated and nonphosphorylated forms of a phosphotransferase constituent regulate the activity of the lactose permease. J Cell Biochem, 1982, 18(2), 231 - 8 Evidence for the functional association of enzyme I and HPr of the phosphoenolpyruvate-sugar phosphotransferase system with the membrane in sealed vesicles of Escherichia coli; Saier MH Jr et al.; Several independent assay procedures were used to estimate the activities of the enzyme constituents of the phosphoenolpyruvate-sugar phosphotransferase system (PTS) in osmotically shocked bacterial membrane vesicles . The soluble enzymes of the system were found to be in association with the membrane by several criteria . Phosphoenolpyruvate-dependent sugar phosphorylation was catalyzed by this membrane-bound enzyme system far more efficiently than by a mixture of the individual enzymes at corresponding concentrations . By contrast, the rates of the phosphoryl exchange reactions catalyzed by enzyme I and the enzyme II complexes were essentially the same for the associated and dissociated forms of the system . Functional association of the PTS-enzyme complex was stabilized by Mg++ and phosphoenolypyruvate and could be destroyed by detergent treatment, sonication, or by passage of the vesicle preparation through a French pressure cell . These results lead to the possibility that in the intact bacterial cell the soluble enzymes of the phosphotransferase system exist, in part, as peripheral membrane constituents associated with the integral membrane enzyme II complexes. Int J Biochem, 1982, 14(2), 127 - 40 Negative cooperativity in alkaline phosphatase from E . col: new kinetic evidence from a steady-state study; Del Arco A et al.; 1 . A study has been carried out on the steady-state kinetics followed by the alkaline phosphatase from Escherichia coli at different pH, temperatures, ionic strengths, phosphate concentrations and in the presence of the effectors such as Tris, NH4+--NH3 and CH3OH; p-nitrophenyl phosphate was used as substrate . 2 . Contrary to what has generally been accepted, in most cases the enzyme follows non-Michaelian kinetics for a wide substrate concentration range, giving concave-down Lineweaver-Burk plots . Only at high phosphate concentrations (5 . 10(-3) M) and at high ionic strengths (2.0 M) is a linear Lineweaver-Burk plot obtained (Michaelian kinetics) . 3 . In order to analyse the kind of kinetics obtained, a non-linear regression fitting method was used to obtain rate vs substrate concentration equations as polynomial quotients of minimum degree with positive coefficients . 4 . Most of the data obtained follows 2:2 degree type equations . 5 . These results tend to suggest an idea of cooperativity rather than one of independence between the sites of the dimeric enzyme . A model is discussed for cooperativity between the sites with a wide concentration range giving concave-down Lineweaver-Burk plots. Circ Shock, 1982, 9(1), 37 - 45 Effect of endotoxin and glucocorticoid pretreatment on hexose monophosphate shunt activity in rat liver; Kuttner RE et al.; The acceleration of glycolysis by the Embden-Meyerhof pathway (EMP) in endotoxic and septic states and its counteraction by glucocorticoids has been demonstrated by past research . Although the glycolytic contribution of the hexose monophosphate (HMP) shunt is minor, its response during endotoxemia, if similar to that of EMP, could be theoretical interest, Fasted male rats (150-260 gm) were sacrificed at 5 hr after IV injection of E coli endotoxin in dosages of 2 or 3 mg/100 gm rat weight: LD50 (Nm= 15) . A second group received 1 mg dexamethasone (DMS) IV per 100 gm rat weight simultaneously with endotoxin (N = 15) . Livers were homogenized in 0.25 M cold sucrose and centrifuged at 15,000 g for 20 min . Specific activity of glucose-6-phosphate dehydrogenase (G6PDH) in control livers (N = 17) was 7.1 nmoles of substrate consumed per min/mg biuret protein . Endotoxin raised G6PDH activity by 49% to 10.64 units, and the endotoxin-DMS-protected group was 6.0 units . Levels of 6-phosphogluconate (6PG) were also measured in frozen liver biopsies from similar groups of rats . Liver 6PG concentrations of control (N = 15), endotoxic (N = 15), and endotoxified-DMS-treated (N = 9) groups were 22.5, 14.3, and 17.6 nmoles/gm wet tissue, respectively . The data indicate a significant 36% acceleration in 6PG consumption during endotoxemia, which is not blocked by DMS . The cofactor, nicotinamide adenine dinucleotide phosphate (NADP), decreased significantly by 18% from the control level of 152 nmoles/gm liver (N = 9) during endotoxemia, and this fall was not corrected by DMS . In a small group (N = 6), sedoheptulose-7-phosphate declined from the control value of 76 nmoles/gm wet liver by 38% after endotoxification . It is concluded that endotoxin stimulates G6PDH, the initial enzyme of the HMP pathway, and accelerates consumption of several intermediates, Glucocorticoid prevents the enzyme activity increase but does not restore 6PC and NADP concentrations to normal levels, suggesting that different enzyme sites along the HMP shunt may have unequal responses to DMS. Carcinogenesis, 1982, 3(2), 139 - 45 Evaluation of the carcinogenic potential of 2,4-dinitrofluorobenzene and its implications regarding mutagenicity testing; Warren ST et al.; Tumor promoters are compounds which dramatically enhance the appearance of tumors when chronically applied after an initiating dose of a carcinogen . Initiators are generally considered mutagens while p