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)

Saccharomyces cerevisiae activates general amino acid control (GCN) in response to amino acid starvation. Some aspects of this response are known to be conserved in other fungi including Candida albicans, the major systemic fungal pathogen of humans. Here, we describe a proteomic comparison of the GCN responses in S. cerevisiae and C. albicans. We have used high-resolution two-dimensional (2-D) gel electrophoresis and peptide mass fingerprinting to develop a 2-D protein map of C. albicans. A total of 391 protein spots, representing 316 open reading frames, were identified. Fifty-five C. albicans and 65 S. cerevisiae proteins were identified that responded reproducibly to 3-aminotriazole (3AT) in a Gcn4p-dependent fashion. The changes in the S. cerevisiae proteome correlated with the response in the S. cerevisiae transcript profile to 3AT treatment (rank correlation coefficient = 0.59; Natarajan et al., Molec. Cell. Biol. 2001, 21, 4347-4368). Significant aspects of the GCN response were conserved in C. albicans and S. cerevisiae. In both fungi, amino acid biosynthetic enzymes on multiple metabolic pathways were induced by 3AT in a Gcn4p-dependent fashion. Carbon metabolism functions were also induced. However, subtle differences were observed between these fungi. For example, purine biosynthetic enzymes were induced in S. cerevisiae, but were not significantly induced in C. albicans. These differences presumably reflect the contrasting niches of these relatively benign and pathogenic yeasts, respectively.
 ...
PMID:Proteomic response to amino acid starvation in Candida albicans and Saccharomyces cerevisiae. 1527 37

This study examines the effect of carbon starvation on the ability of a Moraxella sp. strain to degrade p-nitrophenol (PNP). Carbon starvation for 24 h decreased the induction time for p-nitrophenol degradation by the bacterium in a minimal salt medium from 6 to 1 h but it did not completely eliminate the induction time. Moraxella cells with 2-day carbon starvation had an induction time of 3 h and the induction time of the 3-day starved cells was 6 h. A 100% increase in density of the non-starved cells did not affect the induction time for p-nitrophenol degradation by the bacterium, indicating that the initial increase in cell density of the carbon-starved culture did not cause the faster onset of p-nitrophenol degradation. However, the initial uptake of p-nitrophenol of the 1-day carbon-starved Moraxella cells was 3-fold higher than the non-starved cells. A green fluorescent protein gene (gfp)-labelled Moraxella (M6 strain) was constructed to examine the survival of and p-nitrophenol degradation by the bacterium in non-sterile river water samples. Similar p-nitrophenol degradation behaviour was observed in the river water samples inoculated with the M6 cells. The time needed for complete degradation of p-nitrophenol by the non-starved M6 was 19-27 and 33 h in samples spiked with 80, 200 and 360 microM p-nitrophenol, respectively. However, the 1-day carbon-starved inocula required about 16 h to degrade the p-nitrophenol completely regardless of its concentration in the water samples. Survival of the carbon-starved and non-starved M6 was not significantly different from each other in the river water regardless of the p-nitrophenol concentration. In the absence of p-nitrophenol, the inoculum density decreased continuously. At 200 and 360 microM p-nitrophenol, the cell densities of M6 increased in the first two days of incubation and declined steadily afterward.
 ...
PMID:Effect of carbon starvation on p-nitrophenol degradation by a Moraxella strain in buffer and river water. 1632 72

Carbon-starved cultures of strain Ant-300, a psychrophilic marine vibrio isolated from the Antarctic Convergence, were compared with their nonstarved counterparts for resistance to heat. Specifically, starved and unstarved cells were exposed to 17 degrees C, which is 4 degrees C above the maximum growth temperature, and compared with cells maintained at the optimum temperature (5 to 7 degrees C). Total cell counts, direct viable-cell counts, and plate counts were monitored. At a temperature of 17 degrees C, viability (as indicated by plate counts) was lost within 40 h, with direct viable-cell counts indicating less than 5% viability at this time. However, when cells were carbon starved for 1 week prior to heat challenge, significant plateability was maintained for more than 6 days; direct viable-cell counts of starved cells maintained at 17 degrees C indicated the presence of viable cells for at least 12 days. Because starvation is the normal physiological state of copiotrophic, heterotrophic bacteria in oligotrophic marine waters, these data suggest that starvation conditions may be a significant factor in providing heat tolerance to psychrophiles.
 ...
PMID:Starvation-induced thermal tolerance as a survival mechanism in a psychrophilic marine bacterium. 1634 20

We studied the impact of grazing and substrate supply on the size structure of a freshwater bacterial strain (Flectobacillus sp.) which showed pronounced morphological plasticity. The cell length varied from 2 to >40 microm and encompassed rods, curved cells, and long filaments. Without grazers and with a sufficient substrate supply, bacteria grew mainly in the form of medium-sized rods (4 to 7 microm), with a smaller proportion (<10%) of filamentous forms. Grazing experiments with the bacterivorous flagellate Ochromonas sp. showed that freely suspended cells of <7 microm were highly vulnerable to grazers, whereas filamentous cells were resistant to grazing and became enriched during predation. A comparison of long-term growth in carbon-limited chemostats with and without grazers revealed that strikingly different bacterial populations developed: treatments with flagellates were composed of >80% filamentous cells. These attained a biomass comparable to that of populations in chemostats without grazers, which were composed of medium-sized rods and c-shaped cells. Carbon starvation resulted in a fast decrease in cell length and a shift towards small rods, which were highly vulnerable to grazing. Dialysis bag experiments in combination with continuous cultivation revealed that filament formation was significantly enhanced even without direct contact of bacteria with bacterivores and was thus probably stimulated by grazer excretory products.
 ...
PMID:Direct and indirect effects of protist predation on population size structure of a bacterial strain with high phenotypic plasticity. 1639 Oct 28

Spirodela oligorrhiza plants were used to study direct effects of light on plastid gene expression uncoupled from sequential chloroplast-developmental processes. Specific transcript levels were analysed using chloroplast, gene-fragment probes. Protein synthesis in vivo and in vitro was also measured. In tissue with mature chloroplasts, light/dark regimes had no substantial effect on transcript levels of the psbA gene coding for the 32-kd protein. However, under the same conditions, synthesis of the protein itself was dramatically affected. We conclude that in mature chloroplasts synthesis of 32-kd protein is regulated mainly at a translational level. Transcript levels of the rbcL gene, coding for the large subunit of ribulosebisphosphate carboxylase-oxygenase, were somewhat sensitive to light/dark effects, although not to the same degree as was synthesis of the protein. We conclude that translational events and transcript levels are involved in regulating synthesis of this polypeptide. Carbon deprivation in the dark reduced psbA and rbcL transcript levels appreciably below those found in non-starved, dark-grown tissue. This suggests that starvation and dark effects must be experimentally separated from each other for valid conclusions to be drawn about light/dark regulation of chloroplast gene expression.
 ...
PMID:Control of psbA gene expression: in mature Spirodela chloroplasts light regulation of 32-kd protein synthesis is independent of transcript level. 1645 5

Pseudomonas putida mt-2(pWWO) exhibited a carbon starvation response in the presence of toluene, a utilizable carbon source. When growth-supporting (4-mg/liter), inhibitory (130-mg/liter), and lethal (267-mg/ liter) levels of toluene were provided as the sole carbon source, P. putida responded by rapidly inhibiting protein synthesis and by producing 26 new proteins, 22 of which overlapped with those induced by carbon starvation. P. putida produced the same proteins when cultures were starved by depleting their carbon source or were downshifted into a carbon-free medium. Carbon supplementation of toluene-exposed cells suppressed the production of the toluene-induced proteins. The level of toluene provided as the sole carbon source influenced the length of time that this response was observed. Following 1.5 to 3 h in a basal salts medium with 4 mg of toluene per liter, protein synthesis increased, the production of the majority of the toluene-induced proteins ceased, and the cells began to grow. In cells provided with 130 mg of toluene per liter, protein synthesis remained inhibited over a 6.5-h experimental period. At this concentration, the production of 15 toluene-induced proteins was prolonged, with nine still detectable in the profiles at 6.5 h. In cells provided with 267 mg of toluene per liter, there was a rapid loss of viability and the toluene-induced proteins were detected prior to death. In cells provided with 4 mg of toluene per liter, the carbon starvation response is transient and likely reflects a period of induction and/or adaptation prior to growth on toluene. At the toluene concentrations which inhibit growth, P. putida exhibits a prolonged starvation response despite the presence of an excess of a utilizable carbon source.
 ...
PMID:Toluene Elicits a Carbon Starvation Response in Pseudomonas putida mt-2 Containing the TOL Plasmid pWW0. 1653 5

Carbon-energy source starvation is a commonly encountered stress that can influence the epidemiology and virulence of Salmonella enterica serovars. Salmonella responds to C-starvation by eliciting the starvation-stress response (SSR), which allows for long-term C-starvation survival and cross-resistance to other stresses. The stiC locus was identified as a C-starvation-inducible, sigma(S)-dependent locus required for a maximal SSR. We report here that the stiC locus is an operon composed of the yohC (putative transport protein) and pbpG (penicillin-binding protein-7/8) genes. yohC pbpG transcription is initiated from a sigma(S)-dependent C-starvation-inducible promoter upstream of yohC. Another (sigma(S)-independent) promoter, upstream of pbpG, drives lower constitutive pbpG transcription, primarily during exponential phase. C-starvation-inducible pbpG expression was required for development of the SSR in 5 h, but not 24 h, C-starved cells; yohC was dispensable for the SSR. Furthermore, the yohC pbpG operon is induced within MDCK epithelial cells, but was not essential for oral virulence in BALB/c mice. Thus, PBP 7 is required for physiological changes, occurring within the first few hours of C-starvation, essential for the development of the SSR. Lack of PBP 7, however, can be compensated for by further physiological changes developed in 24 h C-starved cells. This supports the dynamic overlapping and distinct nature of resistance pathways within the Salmonella SSR.
 ...
PMID:Sigma(s)-Dependent carbon-starvation induction of pbpG (PBP 7) is required for the starvation-stress response in Salmonella enterica serovar Typhimurium. 1760 59

A simple way to prevent protein hyperglycosylation in Hansenula polymorpha was found. When glucose oxidase from Aspergillus niger and carboxymethyl cellulase from Bacillus subtilis were expressed under the control of an inducible methanol oxidase (MOX) promoter using methanol as a carbon source, hyperglycosylated forms occurred. In contrast, MOX-repressing carbon sources (e.g., glucose, sorbitol, and glycerol) greatly reduced the extent of hyperglycosylation. Carbon source starvation of the cells also reduced the level of glycosylation, which was reversed to hyperglycosylation by the resumption of cell growth. It was concluded that the proteins expressed under actively growing conditions are produced as hyperglycosylated forms, whereas those under slow or nongrowing conditions are as short-glycosylated forms. The prevention of hyperglycosylation in the Hansenula polymorpha expression system constitutes an additional advantage over the traditional Saccharomyces cerevisiae system in recombinant production of glycosylated proteins.
 ...
PMID:Variations in protein glycosylation in Hansenula polymorpha depending on cell culture stage. 1816 41

Carbon starvation is a significant stress encountered by the opportunistic fungal pathogen Candida albicans, and mutations in several pathways required to assimilate non-fermentable carbon sources attenuate virulence. These pathways -- beta-oxidation, the glyoxylate cycle and gluconeogenesis -- are compartmentalized in the fungal cell between the peroxisome, mitochondria and cytosol; thus, the cell must transport key intermediates between these organelles. Transport of acetyl-CoA, a particularly important intermediate of carbon metabolism, is catalysed by membrane-associated carnitine acetyltransferases (CATs). We report here the characterization of the three predicted CAT genes in C. albicans, CTN1, CTN2 and CTN3. Strains lacking CTN1 or CTN2 were unable to grow on ethanol or acetate as sole carbon source; additionally, citrate was utilized poorly (Deltactn2) or not at all (Deltactn1) and the Deltactn2 mutant failed to grow on fatty acids as well. In contrast, deletion of CTN3 had no observable phenotype. All three genes were upregulated in the presence of non-fermentable carbon sources and after macrophage phagocytosis. CTN1 and CTN3 were able to complement the corresponding Saccharomyces cerevisiae Deltayat1 and Deltayat2 mutants. However, these mutants had no obvious attenuation in virulence in a mouse model of disseminated candidiasis, in contrast to other carbon metabolism mutants. These findings extend our understanding of nutrient stress in vivo and in vitro and the contribution of metabolic pathways to virulence in C. albicans.
 ...
PMID:Carnitine acetyltransferases are required for growth on non-fermentable carbon sources but not for pathogenesis in Candida albicans. 1822 54

This study sought to identify the factors and conditions that affected production of the antifungal glycolipid flocculosin by the biocontrol agent Pseudozyma flocculosa. For this purpose, different parameters known or reported to influence glycolipid release in fungi were tested. Concentration of the start-up inoculum was found to play an important role in flocculosin production, as the optimal level increased productivity by as much as tenfold. Carbon availability and nitrogen source (i.e., organic vs inorganic) both had a direct influence on the metabolism of P. flocculosa, leading to flocculosin synthesis. In general, if conditions were conducive for production of the glycolipid, carbon availability appeared to be the only limiting factor. On the other hand, if yeast extract was supplied as nitrogen source, fungal biomass was immediately stimulated to the detriment of flocculosin synthesis. Unlike other reports of glycolipid release by yeast-like fungi, inorganic nitrogen starvation did not trigger production of flocculosin. The relationship between the factors influencing flocculosin production in vitro and the conditions affecting the release of the molecule by P. flocculosa in its natural habitat appears to be linked to the availability of a suitable and plentiful food source for the biocontrol agent.
 ...
PMID:Nutritional regulation and kinetics of flocculosin synthesis by Pseudozyma flocculosa. 1854 44


<< Previous 1 2 3 4 5 6 7 Next >>