Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The expression of cell cycle events in Caulobacter crescentus CB13 has been shown to be associated with regulation of carbohydrate utilization. Growth on lactose and galactose depends on induction of specific enzymes. Prior growth on glucose results in a delay in enzyme expression and cell cycle arrest at the nonmotile, predivisional stage. Dibutyryl cyclic adenosine 3',5'-monophosphate (AMP) was shown to stimulate expression of the inducible enzymes and, thus, the initiation of the cell cycle. beta-Galactosidase-constitutive mutants did not exhibit a cell cycle arrest upon transfer of cultures from glucose to lactose. Furthermore, carbon source starvation results in accumulation of the cells at the predivisional stage. The cell cycle arrest therefore results from nutritional deprivation and is analogous to the general control system exhibited by yeast (Hartwell, Bacteriol. Rev. 38:164-198, 1974; Wolfner et al., J. Mol. Biol. 96:273-290, 1975), which coordinates cell cycle initiation with metabolic state. Transfer of C. crescentus CB13 from glucose to mannose did not result in a cell cycle arrest, and it was demonstrated that this carbon source is metabolized by constitutive enzymes. Growth on mannose, however, is stimulated by exogenous dibutyryl cyclic AMP without a concomitant increase in the specific activity of the mannose catabolic enzymes. The effect of cyclic AMP on growth on sugars metabolized by inducible enzymes, as well as on sugars metabolized by constitutive enzymes, may represent a regulatory system common to both types of sugar utilization, since they share features that differ from glucose utilization, namely, temperature-sensitive growth and low intracellular concentrations of cyclic guanosine 3',5'-monophosphate.
 ...
PMID:Effect of carbon source and the role of cyclic adenosine 3',5'-monophosphate on the Caulobacter cell cycle. 19 60

The GLN1 gene of Saccharomyces cerevisiae was cloned by complementation of a gln1 auxotroph. A GLN1-lacZ fusion was constructed to assay GLN1 promoter activity. beta-Galactosidase and glutamine synthetase expression in chromosomally integrated GLN1-lacZ fusion strains were co-regulated in response to a shift from glutamine to glutamate as the nitrogen source, purine limitation, and 3-aminotriazole-induced histidine starvation. Regulation of GLN1 expression by each of the three pathways occurred at the transcriptional level. Increased accumulation of GLN1 mRNA was observed within 5 min after a shift from glutamine to glutamate as the nitrogen source. After 5 min, GLN1 mRNA levels were constant. The level of GLN1 transcript was reduced by approximately 75% within 5 min following glutamine addition to the cells growing with glutamate as nitrogen source. This indicates that the GLN1 message is unstable and has a half-life of approximately 3 min. Deletion analysis indicated that the sequences required for GLN1 expression are located within approximately 350 bp upstream from the transcriptional initiation site.
 ...
PMID:Three regulatory systems control expression of glutamine synthetase in Saccharomyces cerevisiae at the level of transcription. 257 Mar 48

Some metabolic modifications of Escherichia coli cells during starvation in seawater were studied in laboratory microcosms. The apparent die-off of this bacterium under such conditions, as observed by comparing the enumeration of CFU in conventional freshwater media and direct epifluorescence counts, was partially prevented when cells were previously grown in salted organic medium or on seawater-wastewater agar. beta-Galactosidase activity of starved cells disappeared gradually with time, even though some other enzymatic activities, such as that of alkaline phosphatase, increased. Moreover, some modifications of sensitivity to antibiotics, heavy metals, and bacteriophages in seawater- and wastewater-grown cells suggested that the cells undergo structural changes under natural marine conditions. These results provide additional experimental data indicating the possible active adaptation of E. coli cells to seawater.
 ...
PMID:Changes in Escherichia coli cells starved in seawater or grown in seawater-wastewater mixtures. 311 27

A purE::lac fusion strain was isolated by using a special Mu phage developed by M. Casadaban. In the presence of adenine (100 micrograms/ml), beta-galactosidase synthesis was repressed by greater than 90%. beta-Galactosidase activity could be detected 6 to 8 min after the removal of adenine and increased linearly for at least 20 min. purR- mutants were isolated and synthesized 1.7- to 1.8-fold-higher levels of beta-galactosidase compared with purR+ cells. Azaserine derepressed purE transcription approximately 1.7-fold by lowering purine nucleotide pools. Glutamine and pyrimidine supplementation or starvation had no effect on purE transcription. A comparison of the rate of de novo purine biosynthesis and purE transcription indicated that the in vivo rate of de novo purine biosynthesis was more sensitive to the inhibitory effects of adenine than was transcription at the purE locus.
 ...
PMID:Regulation of purE transcription in a purE::lac fusion strain of Escherichia coli. 703 38

Two Tn5 lac insertions into the Myxococcus genome at sites omega 4414 and omega 4473, which are separated by 550 nucleotides, inactivate fruiting body development. Sporulation is decreased 100- to 10,000-fold. At least two genes, devR and devS, are transcribed in this region, probably as an operon. Expression of devR begins by 6 h after starvation has initiated development. On the basis of their nucleotide sequences, devR and devS are expected to encode proteins of 302 and 214 amino acids, respectively. Dev+ function can be restored by a segment of 7.8 kb cloned from the devRS region of wild-type cells. Two experiments show that devR expression is under strong negative autoregulation. beta-Galactosidase is expressed at a higher level from a transcriptional devR::lacZ fusion when the fused operon is in a dev strain than when it is in the dev/dev+ genetic background of a partial diploid. There is more mRNA accumulation from the devRS region in the dev strain than in a rescued dev/dev+ tandem duplication strain. Sporulation rescue is correlated with some degree of negative autoregulation, even though sporulation is not inversely proportional to beta-galactosidase expression from omega 4414. A second level of regulation is suggested by complementation of dev by dev+ in duplication strains. The expression of devRS, measured by sporulation levels, differs 1,000-fold when devRS+ is moved from a distance of 20 kb to 3 Mb from the mutant devRS locus. Expression of devR is also dependent on the cell density at which development is initiated, a third level of regulation. Multiple levels of regulation suggest that devRS is a switch required to activate completion of aggregation and sporulation.
 ...
PMID:devRS, an autoregulated and essential genetic locus for fruiting body development in Myxococcus xanthus. 769 58

Expression of the Aspergillus nidulans brlA gene plays a fundamental role in the switch from vegetative growth to asexual reproduction. Using a media-shifting protocol to induce submerged sporulation and brlA-lacZ as an expression marker, it was shown that carbon and nitrogen starvation stress induced brlA transcription to different degrees. Glucose starvation induced briA rapidly to high levels and resulted in spore formation on reduced conidiophores, whereas nitrogen starvation induced brlA gradually to lower levels and sporulation occurred to a lesser extent but from more complex conidiophores. beta-Galactosidase activity paralleled brlA alpha and brlA beta mRNA. No clear qualitative differences between the two brlA transcripts were found in these starvation conditions, suggesting that the different patterns of sporulation could be explained by quantitative expression differences. Since brlA mRNA did not accumulate in the presence of a high glucose concentration, we investigated the role of other carbon sources on brlA expression. Non-repressing carbon sources such as glycerol, acetate and arabinose were as effective as glucose in preventing brlA mRNA accumulation, suggesting that the glucose effects on brlA expression could be explained as a response to nutrient starvation, rather than by carbon catabolite repression. Despite similar low levels of brlA transcripts being detected during growth in glucose or non-repressing carbon sources, conidiophores were formed only in medium containing glycerol, acetate or arabinose. When mycelia were not shifted to starvation conditions, sporulation was not observed in standard minimal medium even after glucose was exhausted, unless the medium was buffered.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Starvation stress modulates the expression of the Aspergillus nidulans brlA regulatory gene. 789 14

Sequence data for genes encoding 16S rRNA indicated that the marine strain previously named Pseudomonas sp. strain S9 would be better identified as a Pseudoalteromonas sp. By use of transposon mutagenesis, a chitinase-negative mutant of S9 with a lacZ reporter gene insertion was isolated. Part of the interrupted gene was cloned and sequenced. The deduced amino acid sequence had homology to sequences of bacterial chitinases. Expression of the chitinase gene promoter was quantified by measuring the lacZ reporter gene product, beta-galactosidase, beta-Galactosidase production was induced 10-fold by N-acetylglucosamine and 3-fold by chitin in minimal medium. Repression of beta-galactosidase synthesis was observed in rich medium either with or without chitin but was not observed in minimal medium containing glucose. The chitinase gene promoter was induced by starvation and higher-than-ambient levels of carbon dioxide but not by cadmium ion, heat or cold shock, or UV exposure.
 ...
PMID:Use of a promoterless lacZ gene insertion to investigate chitinase gene expression in the marine bacterium Pseudoalteromonas sp. strain S9. 925 Nov 87

Polyphosphate kinase (Ppk) catalyzes the formation of polyphosphate from ATP. We cloned the ppk gene (2,073 bp) from Acinetobacter sp. strain ADP1; this gene encodes a putative polypeptide of 78.6 kDa with extensive homology to polyphosphate kinase from Escherichia coli and other bacteria. Chromosomal disruption of ppk by inserting a transcriptionally fused lacZ does not affect growth under conditions of phosphate limitation or excess. beta-Galactosidase activity expressed from the single-copy ppk::lacZ fusion is induced 5- to 15-fold by phosphate starvation. An increased amount of ppk transcript (2.2 kb) was detected when cells were grown at a limiting phosphate concentration. Primer extension analysis revealed a regulated promoter located upstream of a second, constitutive promoter. Potential similarities of this regulation with the effects of PhoB and PhoR of E. coli are discussed.
 ...
PMID:Transcription of ppk from Acinetobacter sp. strain ADP1, encoding a putative polyphosphate kinase, is induced by phosphate starvation. 950 29

beta-Galactosidase activity of Escherichia coli was investigated in response to long-term starvation, changes in temperature and the presence of certain nutrient sources in lake water. beta-Galactosidase activity decreased markedly in filtered-autoclaved lake water at 25 degrees C and 37 degrees C, whereas it remained almost constant at 4 degrees C and 15 degrees C for 60 days. Increases in beta-galactosidase activity were observed in response to the following nutrient sources: glycine, serine, methionine and ammonium sulfate at 4 degrees C; glycine and ammonium sulfate at 15 degrees C; glycine, serine, methionine and ammonium sulfate at 30 degrees C. Glycine addition led to an increase in beta-galactosidase activity of almost five and seven orders of magnitude at 15 degrees C and 30 degrees C, respectively. In addition, L-methionine had the strongest influence on beta-galactosidase activity, which was detected as an increase of seven and eleven orders of magnitude at 4 degrees C and 30 degrees C, respectively. The effect of several amino acids and other nitrogen sources depended on the concentration of the nutrient source and the temperature. The results showed that, in lake water, long-term starvation, temperature change, and variations in nitrogen sources alter beta-galactosidase activity. Those effects should be taken into account when monitoring coliforms from the environment.
 ...
PMID:beta-Galactosidase activity of Escherichia coli under long-term starvation, alterations in temperature, and different nutrient conditions in lake water. 1220 14

Introduction of bcl-2 gene in EIA + c-Ha-ras-transformed rat embryo fibroblasts, which are unable to be arrested after damaging influences and possess high proapoptotic sensitivity, results not only in suppression of cell death but also in re-establishment of cell cycle block following DNA damage and serum starvation. Flow cytometry showed that E1A + c-Ha-ras + bcl-2-transformants treated with DNA-intercalator adriamycin are capable of being arrested at G1/S boundary for a long time (for less than 5 days). According to the growth curve data, the number of Bcl-2-overexpressing cells remanins constant for a week of cultivation with adriamycin. Clonogenic efficacy of E1A + c-Ha-ras + bcl-2-cells is brought to no already in 16 h after adriamycin addition. Apoptotic death, revealed by oligonucleosomic fragmentation of DNA, as well as cell death, occurring due to mitotic catastrophe, after adriamycin treatment are almost absent in Bcl-2-overexpressing transformants, as compared with parental E1A + c-Ha-ras-transformants. Bcl-2 introduction in E1A + c-Ha-ras-transformants is accompanied by a rise of SA beta-Gal (Senescence Associated beta-Galactosidase) activity, which is commonly considered to be a marker of cell senescence. Adriamycin treatment of E1A + c-Ha-ras + bcl-2-transformants results in a much higher rise in SA beta-Gal activity, as compared with untreated cells. Co-immunoprecipitation experiments demonstrated the introduction of Bcl-2 to result in formation of Bcl-2 complexes with early region E1A oncoproducts, which are thought to be responsible for proapoptotic susceptibility of E1A-expressing transformants. The data obtained lead to suggestion that bcl-2 transfer to E1A + c-Ha-ras-transformants may induce a switch from the cell death program on the program of senescence after DNA damage, due, presumably, to Bcl-2 interaction with the apoptosis activator the viral oncoprotein E1A.
 ...
PMID:[Antiapoptotic oncogene bcl-2 induces a program of senescence in E1A + c-Ha-ras-transformants treated with adriamycin]. 1671 90


1 2 Next >>