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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Considerable decrease of polysome number (22% as compared with 48% in normally grown culture) was observed under methionine starvation of E. coli Hfr (Met-)culture . At the same time the amount of 70S ribosomes increased up to 32%, while it was 2--6% in the control, the content of free ribosome subunits (50S+30S) being stable. The number of polysomes was the same (congruent to 50%) both in the control culture and under inhibition of protein synthesis in E. coli Hfr(Met-) cells with chloramphenicol, the content of 70S ribosomes was increased (30%) like in the case of methionine starvation, and the amount of free ribosome subunits was decreased (24% as compared with 46% in the control). The rate of ribosome movement in polysomes in the presence of chloramphenicol is comparable with that in the control. The rate of ribosome movement along mRNA under methionine starvation in 1.6 times lower than in normally grown E.coli culture. The level of (14)C-leucine incorporation into newly synthesizing polysome proteins under chloramphenicol inhibition of protein synthesis and methionine starvation comprised 20% and 12% of the incorporation level inthe control respectively. It suggested that ribosomes under inhibition of protein synthesis by chloramphenicol or amino acid starvation continue their movement along mRNA with the rate comparable with that in the control. However in this case no peptide bonds are formed ("abortive" translocation).
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PMID:[Rate of ribosome movement along messenger RNA in E. coli under normal and inhibited translation]. 79 17

Prior treatment of Escherichia coli with nalidixic acid in nutritionally complete medium altered the subsequent pattern of deoxyribonucleic acid (DNA) synthesis normally observed in nutritionally deficient medium. Transfer of E. coli 15 TAU to an amino acid- and pyrimidine-deficient medium usually resulted in a 40 to 50% increase in DNA content. Previous treatment with nalidixic acid caused a 200 to 300% increase in DNA content under these conditions. The extent of this DNA synthesis depended on the duration of prior exposure to nalidixic acid. The maximal rate of synthesis was obtained after a 40- to 60-min exposure to nalidixic acid and was two to three times that of the control. The induction of this excessive DNA synthesis was prevented by chloramphenicol or phenethyl alcohol, but the synthesis of this DNA was only partially sensitive to these agents. With E. coli TAU-bar, the rate of DNA synthesis, after removal of nalidixic acid, was similar to that of E. coli 15 TAU, but the maximal amount of DNA synthesized was 180 to 185% of that initially present. Cesium chloride density gradient analysis demonstrated that DNA synthesis after removal of nalidixic acid occurs by a semiconservative mode of replication. The density distribution of this DNA was similar to that obtained after thymine starvation. These results suggest that nalidixic acid treatment may induce additional sites for DNA synthesis in E.coli.
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PMID:Induction of excessive deoxyribonucleic acid synthesis in Escherichia coli by nalidixic acid. 486 1

Unusual guanosine nucleotides synthesised during amino acid or energy source starvation are thought to be the effectors of the stringent response. In vitro experiments suggest that the magic spot compounds alter transcription specificity of RNA polymerase by binding to the enzyme. However, there is no good in vivo evidence for such an interaction. We define sites on the beta-subunit of RNA polymerase which, when altered, yield E.coli mutants apparently insensitive to the presence of ppGpp.
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PMID:Relaxed mutants of Escherichia coli RNA polymerase. 635 28

Previous work has shown that clinical Escherichia coli strains, starved in seawater, are able to present residual growth, with subsequent alterations to their enzymatic activities and metabolism. Gelatinolytic activity of starved cells is of importance because it appears and increases gradually with time. In this work, several forms of gelatinolytic activity were detected by SDS-polyacrylamide gel electrophoresis, differing in molecular masses and appearance, before and after starvation of E. coli cells. The enzymic forms are classified into 4 categories according to the effect of certain inhibitors on the appearance of gelatinolytic activity: a. those whose appearance is inhibited by the chelating factors EDTA, 1,10-phenanthroline and whose presence is also inhibited by N-ethylmaleimide (metalloproteinases with thiol group active); b. those affected by the presence of chelators, N-ethylmaleimide and Ca2+ (Ca2(+)-dependent metalloproteinases with thiol group active); c. those inhibited by chelators and activated in the presence of Ca2+ (Ca2(+)-dependent metalloproteinases) and d. those whose appearance is independent of the presence of inhibitors used. The forms of gelatinolytic activity of the fourth category coincide with enzyme forms that can also use casein as substrate in electrophoresis. These data suggest that there are considerable differences in the gelatinolytic pattern of clinical strains of E.coli cells before and after starvation in seawater.
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PMID:Study of the gelatinolytic activities Escherichia coli cells before and after starvation in seawater by substrate gel electrophoresis. 881 23

Prokaryotic chromosomes encode toxin-antitoxin loci, often in multiple copies. In most cases, the function of these genes is not known. The chpA (mazEF) locus of Escherichia coli has been described as a cell killing module that induces bacterial apoptosis during nutritional stress. However, we found recently that ChpAK (MazF) does not confer cell killing but rather, induces a bacteriostatic condition from which the cells could be resuscitated. Results presented here yield a mechanistic explanation for the detrimental effect on cell growth exerted by ChpAK and the homologous ChpBK protein of E.coli. We show that both proteins inhibit translation by inducing cleavage of translated mRNAs. Consistently, the inhibitory effect of the proteins was counteracted by tmRNA. Amino acid starvation induced strong transcription of chpA that depended on Lon protease but not on ppGpp. Simultaneously, ChpAK cleaved tmRNA in its coding region. Thus, ChpAK and ChpBK inhibit translation by a mechanism very similar to that of E.coli RelE. On the basis of these results, we propose a model that integrates TA loci into general prokaryotic stress physiology.
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PMID:Toxin-antitoxin loci as stress-response-elements: ChpAK/MazF and ChpBK cleave translated RNAs and are counteracted by tmRNA. 1297 53

We report on a new type of systematic annotation error in genome and pathway databases that results from the misinterpretation of partial Enzyme Commission (EC) numbers such as '1.1.1.-'. This error results in the assignment of genes annotated with a partial EC number to many or all biochemical reactions that are annotated with the same partial EC number. That inference is faulty because of the ambiguous nature of partial EC numbers. We have observed this type of error in multiple databases, including KEGG, VIMSS and IMG, all of which assign genes to KEGG pathways. The Escherichia coli subset of the KEGG database exhibits this error for 6.8% of its gene-reaction assignments. For example, KEGG contains 17 reactions that are annotated with EC 1.1.1.-. A group of three E.coli genes, b1580 [putative dehydrogenase, NAD(P)-binding, starvation-sensing protein], b3787 (UDP-N-acetyl-D-mannosaminuronic acid dehydrogenase) and b0207 (2,5-diketo-D-gluconate reductase B), is assigned to 15 of those reactions, despite experimental evidence indicating different single functions for two of the three genes. Furthermore, the databases (DBs) are internally inconsistent in that the description of gene functions for genes with partial EC numbers is inconsistent with the activities implied by reactions to which the genes were assigned. We infer that these inconsistencies result from the processing used to match gene products to reactions within KEGG's metabolic pathways. These errors affect scientists who use these DBs as online encyclopedias and they affect bioinformaticists who use these DBs to train and validate newly developed algorithms.
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PMID:Genome annotation errors in pathway databases due to semantic ambiguity in partial EC numbers. 1603 25

Human acidic fibreblast growth factor (haFGF) was a kind of cell growth factor with wide bio-activity on cell from mesectoderm and neuro-ectoderm.In this paper, the effect of acetate concentration on the growth and expression of recombinant human acidic fibroblast growth factor mutant system E.coli BL21(DE3)/pET3C-haFGF was investigated. Four fed-batch modes: batch-fed, batch-DO static balance, DO static balance-glucose starvation, and pH-static state were investigated. The accumulation of acetate during the fermentation course was effectively inhibited. The OD600nm value was about 22, after purification, the soluble rhaFGF yielded 450mg/L. During the fermentation, no special ways such as pure oxygen, pressure were adopted, thus the established process would be easily scaled up for industry purpose.
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PMID:[Research of the feeding strategy in the fermentation of recombinant human fibreblast growth factor mutant]. 1660 64