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

The regulation of phospholipid synthesis in cells of Escherichia coli was studied in vivo during growth and during the stringent response to amino acid starvation. Strains harboring the hybrid plasmid pLC44-14 (Clark, L., and Carbon, J. (1976) Cell 9, 91-99), which had increased levels of glycerophosphate acyltransferase, were used to study the involvement of this enzyme in the control of phospholipid synthesis. In addition, regulation was studied by measuring the levels of three early intermediates of phospholipid synthesis:phosphatidic acid, CDP-diglyceride, and dCDP-diglyceride. The liponucleotides were measured by a new enzymatic method which allows determinations to be made on crude lipid extracts. Results from experiments on growing cells are consistent with regulation of membrane lipid synthesis occurring in fatty acid synthesis or at the level of glycerophosphate acylation, but not at any later step. Experiments on the inhibition of lipid synthesis during the stringent response make it possible to rule out explanations which involve the inhibition of a single enzyme; enzymes both before and after the liponucleotides in phospholipid synthesis must be affected.
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PMID:Control of membrane lipid synthesis in Escherichia coli during growth and during the stringent response. 22 65

Three isolates, a Pseudomonas sp., a Bacillus sp. and an Arthrobacter sp., which had been isolated from a meadow soil at Devon Island, Canada, were subjected to starvation under varying conditions. The viabilities of the three isolates during starvation for 30 days in a carbon-free medium was assessed after the organisms had been grown continuously at varying rates in carbon- and nitrogen-limited media at 5 and 15 degrees C. Pseudomonas M216 was the most resistant to starvation stress, Bacillus M153 the least, and Arthrobacter M51 was intermediate in its response. Cells grown and starved at 5 degrees C survived longer than those at 15 degrees C. Carbon-limited Bacillus and Arthrobacter cells grown at high rates prior to starvation survived longer than those grown slowly, while in nitrogen-limited Arthrobacter the reverse was observed. The pattern of endogenous metabolism of the three isolates during starvation at 15 degrees C for 10 days was similar to that observed in other organisms. Levels of endogenous substrates such as carbohydrate and protein showed a rapid decrease in the initial 20 h of starvation, followed by a gradual decline over the remainder of the starvation period. The rates of endogenous metabolism of the isolates were positively correlated with their survival rates during starvation.
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PMID:Effect of starvation on survival of three bacterial isolates from an arctic soil. 74 9

The response of the marine Vibrio sp. strain S14 to starvation for carbon, nitrogen, or phosphorus and to simultaneous depletion of all these nutrients (multiple-nutrient starvation) was examined with respect to survival, stress resistance, quantitative and qualitative alterations in protein and RNA synthesis, and the induction of the stringent control. Of the conditions tested, carbon starvation and multiple-nutrient starvation both promoted long-term starvation resistance and a rapid induction of the stringent control, as deduced from the kinetics of RNA synthesis. Carbon- and multiple-nutrient-starved cells were also found to become increasingly resistant to heat, UV, near-UV, and CdCl2 stress. Nitrogen- and phosphorus-starved cells demonstrated a poor ability to survive in the presence of carbon and did not develop a marked resistance to the stresses examined. The carbon, nitrogen, and phosphorus starvation stimulons consisted of about 20 proteins each, while simultaneous starvation for all the nutrients elicited an increased synthesis of 42 polypeptides. Nine common proteins were found to be induced regardless of the starvation condition used and were tentatively termed general starvation proteins. It was also demonstrated that the total number of proteins induced in response to multiple-nutrient starvation was not a predictable sum of the different individual starvation stimulons. Multiple-nutrient starvation induced 14 proteins which were not detected at increased levels of expression in response to individual starvation conditions. Furthermore, four out of five phosphorus starvation-specific polypeptides were not induced during simultaneous starvation for phosphorus, nitrogen, and carbon. The results are discussed in light of the physiological alterations previously described for Vibrio sp. strain S14 cells starved for carbon, nitrogen, and phosphorus simultaneously.
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PMID:Survival, stress resistance, and alterations in protein expression in the marine vibrio sp. strain S14 during starvation for different individual nutrients. 137 61

Carbon starvation induces the development of a starvation- and stress-resistant cell state in marine Vibrio sp. strain S14 (CCUG 15956). The starved cells remain highly responsive to nutrients during prolonged starvation and exhibit instantaneous severalfold increases in the rates of protein synthesis and RNA synthesis when substrate is added. In order to elucidate the physiological basis for the survival of cells that are starved for a long time, as well as the capacity of these cells for rapid and efficient recovery, we analyzed the ribosome content of carbon-starved Vibrio sp. strain S14 cells. By using direct chemical measurements of the amounts of ribosomal particles in carbon-starved cultures, we demonstrated that ribosomes were lost relatively slowly (half life, 79 h) and that they existed in large excess over the apparent demand for protein synthesis. After 24 h of starvation the total rate of protein synthesis was 2.3% of the rate during growth, and after 3 days this rate was 0.7% of the rate during growth; the relative amounts of ribosomal particles at these times were 81 and 52%, respectively. The ribosome population consisted of 90% 70S monoribosomes, and no polyribosomes were detected in the starved cells. The 70S monoribosomes were responsible for the bulk of the protein synthesis during carbon starvation; some activity was also detected in the polyribosome size region on sucrose density gradients. We suggest that nongrowing carbon-starved Vibrio sp. strain S14 cells possess an excess protein synthesis capacity, which may be essential for their ability to immediately initiate an upshift program when substrate is added.
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PMID:Ribosomes exist in large excess over the apparent demand for protein synthesis during carbon starvation in marine Vibrio sp. strain CCUG 15956. 138 95

Escherichia coli induces the synthesis of at least 30 proteins at the onset of carbon starvation, two-thirds of which are positively regulated by the cyclic AMP (cAMP) and cAMP receptor protein (CRP) complex. Two of the cAMP-CRP-dependent genes mapped to 14 and 93 minutes of the chromosome and are designated cstA and cstB, respectively. The cstA promoter region was cloned and localized to a 600 base-pair fragment downstream from the iron-regulated entCEBA-P15 operon. Carbon starvation-inducible transcription initiated at three sites spaced one turn of the DNA helix apart. All had--10 sequences similar to consensus E sigma 70 promoters and poor--35 sequences. Deletion of a putative CRP binding site abolished carbon starvation-mediated induction. Sequence analysis of the cstA coding region revealed the presence of three sequential open reading frames potentially encoding two hydrophobic proteins of 60,223 Da and 15,201 Da and a hydrophilic protein of 7467 Da. Overexpression of the cstA region produced starvation-inducible proteins of the expected sizes. Suggestive evidence was obtained that cstA is involved in peptide utilization.
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PMID:Molecular and functional characterization of a carbon starvation gene of Escherichia coli. 184

The Salmonella dublin plasmid gene vsdC is essential for virulence. We have constructed a vsdC-lacZ translational fusion to demonstrate that vsdC is selectively expressed during the stationary phase of bacterial cell growth. This pattern of expression has been confirmed by mRNA hybridization studies. Carbon starvation is able to induce vsdC expression by limiting bacterial growth. The expression of vsdC is dependent upon an upstream gene, vsdA, whose gene product possesses significant amino-terminus homology with the LysR family of transcriptional activator proteins. We have further demonstrated that vsdC expression is not dependent upon the known Salmonella chromosomal virulence regulatory loci ompR, phoP, and cya-crp and that vsdC can be expressed in a range of nontyphoidal Salmonella serovars, including some serovars in which introduction of the virulence plasmid does not confer mouse virulence. The vsd system provides a model for the study of transcriptional activation, a basis for the development of new expression vectors, and a novel mechanism of virulence gene regulation. Bacterial growth limitation within the phagosomes of host phagocytic cells may be the environmental signal inducing plasmid-mediated virulence gene expression in salmonellae.
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PMID:Growth regulation of a Salmonella plasmid gene essential for virulence. 193 84

When cultured human lymphoblasts are starved 3 h for an essential amino acid, rates of purine nucleotide synthesis decrease markedly because of a decrease in the intracellular phosphoribosylpyrophosphate concentration (Boss, G.R., and Erbe, R.W. (1982) J. Biol. Chem. 257, 4242-4247; Boss, G. R. (1984) J. Biol. Chem. 259, 2936-2941). In amino acid-starved cells, glucose transport was not changed, whereas total glucose consumption and lactate production decreased by approximately 25 and 10%, respectively. Carbon flow through the oxidative pentose phosphate pathway, measured by 14CO2 release from [1-14C]glucose, decreased by 18% during amino acid starvation. However, kinetic studies of ribulose-5-phosphate 3-epimerase and phosphoriboisomerase suggested that the ribulose 5-phosphate produced by this pathway is converted mostly to xylulose 5-phosphate instead of to ribose 5-phosphate so that this pathway produces little phosphoribosylpyrophosphate. The activity of the nonoxidative pentose phosphate pathway, measured by high performance liquid chromatography following the incorporation of [1-14C]glucose into phosphoribosylpyrophosphate, ATP, and GTP, decreased by approximately 55% during amino acid starvation. None of the enzymes of either pathway changed in specific activity during amino acid starvation. We conclude that the nonoxidative pentose phosphate pathway is the major source of phosphoribosylpyrophosphate for purine nucleotide synthesis and that this pathway is regulated by a metabolite which changes in concentration during amino acid starvation.
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PMID:Phosphoribosylpyrophosphate synthesis from glucose decreases during amino acid starvation of human lymphoblasts. 258 46

Escherichia coli relB mutants react to amino acid starvation by several abnormal responses, including accumulation of a translational inhibitor. We have isolated a relB-complementing plasmid from the Clarke and Carbon E. coli DNA library. From this plasmid we sequenced a 2140-bp segment which included the relB gene by the following two criteria: (i) it complements chromosomal relB mutations, (ii) the corresponding DNA segment cloned from chromosomal DNA of three relB mutants was defective in relB complementation. All three mutations fell within an open reading frame of 79 amino acids. A polypeptide of 9 kd compatible with this open reading frame was synthesized in maxicells and is in all probability the product of the relB gene. By nuclease S1 mapping we have determined the transcription start and stop of an 870 base transcript of the relB gene.
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PMID:Sequence of the relB transcription unit from Escherichia coli and identification of the relB gene. 299 Sep 7

1,2,4-Trichlorobenzene (TCB) and 1,2,4-tribromobenzene (TBB) were administered for 7 d to rats at a dose of 1 mmol/kg.d. The animals were sacrificed at various times to observe the decline in enzyme induction. Carbon 14-labeled TCB and TBB were administered and the disposition of the radioactivity was determined. The influence of starvation and phenobarbital on the inductive effects of TCB and TBB was observed. p-Nitroanisole demethylation and EPN (O-ethyl O-p-nitrophenyl phenylphosphonothionate) detoxification increases declined with time but were still elevated 16 d after the last dose of TBB. Cytochorme P-450 and NADPH-cytochrome c reductase were alsoinduced. Tissue analysis showed greater retention of TBB than of TCB, with highest levels in the fats. More TCB than TBB was excreted in the urine, and fecal excretion was only 5-10% of the dose. The highest enzyme levels were found after 4 d of starvation following the 7 d of treatment and 6 d of recovery. Starvation resulted in increased plasma, fat, and liver concentrations and increased urinary excretion of 14C after TBB dosing. Phenobarbital treatment decreased the levels of induction by the halogenated benzenes. The results demonstrate that, on an equimolar basis, TBB leads to higher levels of induction that are maintained for longer periods than does TCB. Treatments, such as starvation and phenobarbital, that after storage in fat of these materials change the decline with time of the level of induction.
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PMID:Various pharmacokinetic parameters in relation to enzyme-inducing abilities of 1,2,4-trichlorobenzene and 1,2,4-tribromobenzene. 742 Apr 77

The Saccharomyces cerevisiae ALG7, ALG1 and ALG2 genes, whose products function early in the dolichol pathway of protein N-glycosylation, are essential for cell viability, and perturbation in their expression causes G1-specific cell cycle arrest. Here, we show that expression of the ALG7, ALG1 and ALG2 genes is coordinately regulated at the G0/G1 transition point in the yeast life cycle. Carbon starvation, which induces cells to exit from the G1 stage of the mitotic cycle into G0, resulted in a time-dependent decrease in the levels of the early ALG genes' mRNAs. Accordingly, addition of glucose, which stimulates the G0-arrested cells to resume proliferation, resulted in a rapid induction of their mRNAs. Cycloheximide alone also induced the early ALG transcripts, albeit to a much lower extent than glucose. Simultaneous addition of glucose and cycloheximide caused superinduction of these mRNAs, indicating that more than one control level was involved in their activation. Consistent with this, rapid degradation of ALG7, ALG1 and ALG2 mRNAs was completely abolished in the presence of cycloheximide. These data suggest that in yeast, the early N-glycosylation genes are regulated in a manner similar to that of the early growth-response genes.
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PMID:Growth-related coordinate regulation of the early N-glycosylation genes in yeast. 782 5


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