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PubMed1996

Starvation-induced multiresistance in Enterococcus faecalis JH2-2.

Compared with growing bacteria, carbohydrate-starved cells of Enterococcus faecalis show development of a multiresistance state against heat, H2O2, acid, and ethanol, but not against UV irradiation. The kinetics of acquisition of resistance is different according to the stress. Three hours of starvation provide maximal resistance against ethanol, while the tolerance to heat, H2O2, and acid increases progressively with the duration of starvation. Chloramphenicol treatment does not abolish the ethanol tolerance. Protein synthesis inhibition during the transitional growth phase and the first hours of starvation partially inhibit the acquisition of heat and oxidative resistances. Antibiotic treatment after 3 h of starvation does not affect the increase of these resistances. We suggest that synthesis of specific proteins revealed by 2-D gel analysis in the first 3 h of starvation, followed by a second mechanism related to protein degradation or alteration, is necessary for acquisition of maximal resistance towards heat and oxidative stresses.

Bacterial Proteins↗
PubMed2000

Conditional identification of phosphate-starvation-response mutants in Arabidopsis thaliana.

Plants have evolved elaborate metabolic and developmental adaptations to low phosphorus availability. Biochemical responses to phosphate limitation include increased production and secretion of phosphate-acquisition proteins such as nucleases, acid phosphatases, and high-affinity phosphate transporters. However, the signal transduction pathways that sense phosphate availability and integrate the phosphate-starvation response in plants are unknown. We have devised a screen for conditional mutants in Arabidopsis thaliana (L.) Heynh. to dissect signaling of phosphate limitation. Our genetic screen is based on the facultative ability of wild-type Arabidopsis plants to metabolize exogenous DNA when inorganic phosphate is limiting. After screening 50,000 M2 seedlings, we isolated 22 confirmed mutant lines that showed severely impaired growth on medium containing DNA as the only source of phosphorus, but which recovered on medium containing soluble inorganic phosphate. Characterization of nine such mutant lines demonstrated an inability to utilize either DNA or RNA. One mutant line, psr1 (phosphate starvation response), had significantly reduced activities of phosphate-starvation-inducible isoforms of ribonuclease and acid phosphatase under phosphate-limiting conditions. The data suggest that a subset of the selected mutations impairs the expression of more than one phosphate-starvation-inducible enzyme required for utilization of exogenous nucleic acids, and may thus affect regulatory components of a Pi starvation response pathway in higher plants.

Arabidopsis↗
PubMed2007

Transcriptomic adaptations in rice suspension cells under sucrose starvation.

Sugar is an important resource for energy generation and developmental regulation in plants, and sucrose starvation causes enormous changes in cellular morphology, enzyme activities and gene expression. Genome-wide gene expression profiling provides a comprehensive knowledge of gene expression under nutrient depletion and senescence; however, that of a monocot model plant, rice, under sucrose depletion is still under investigation. Here, the time-course monitoring of gene expression profiles in sucrose-starved rice (Oryza sativa cv Tainung67) suspension cells was investigated by 21495 probes contained in Agilent rice chip. In sucrose-starved cells, the induced vacuolar biogenesis coincided with significantly upregulated transcripts of H+-pyrophosphatase, delta-TIP, one putative alpha-TIP, several vacuolar proteases and proteinase inhibitors, and one OsATG3. To survey the overall metabolic adaptations under sucrose depletion, the genes with significantly altered expression level were incorporated into multiple metabolic pathways. Most genes encoding enzymes involved in biosynthesis and degradation pathways of various macromolecules were comprehensively down-and upregulated, respectively, with sucrose starvation. Transcriptional regulation of gene expression is important for physiological adaptations to environmental stress, and many transcription factors, including bZIPs, NACs, and WRKY, showed significant increase in transcriptional level under sucrose starvation. Concurrently, statistical analysis revealed that their corresponding consensus cis-elements, such as ABA-responsive element, CACG, ACI, ACII and CTTATCC, were frequently found in the promoter regions of many sucrose starvation-upregulated genes. Particle bombardment-mediated and luciferase activity-based transient promoter assays revealed the CTTATCC, derived form TATCCA, and the AC motifs to be promising sucrose-starvation responsive activators in rice suspension cells.

Base Sequence↗
PubMed1992

The human multidrug resistance 1 promoter has an element that responds to serum starvation.

We have previously demonstrated in transient expression assay systems that a human multidrug resistance 1 (MDR1) promoter can be directly activated by cytotoxic anticancer agents. In this study, we examined whether the MDR1 promoter could be regulated in response to growth arrest induced by serum starvation. We have established human and rodent cell lines which stably expressed the chloramphenicol acetyltransferase (CAT) gene driven by various lengths of the MDR1, the viral thymidine kinase (TK) and the simian virus 40 (SV40) promoters. Serum starvation caused enhanced expression of CAT gene with MDR1 promoter, but not with two viral gene promoters in human cancer KB cells. Hydroxyurea activated the MDR1 promoter, but not TK and SV40 promoters. By contrast, the DNA topoisomerase II inhibitor, etoposide, equally activated the MDR1, TK and SV 40 promoters. Increased CAT gene expression by serum starvation was also specifically observed in stable transfectants of human adrenal SW-13 cell lines, but not in stable transfectants of mouse fibroblast NIH3T3 and adrenal Y-1 cell lines when the human MDR1 promoter-CAT was introduced. Etoposide, however, effectively induced CAT activity in both human and rodent cells. Assays with deletion constructs of the MDR1 promoter showed that serum starvation activated the MDR1 promoter carrying -258 approximately +121 base sequence of the promoter, but not -198 approximately +121 of the promoter. These results suggest that the expression of the MDR1 gene induced by serum starvation is regulated at the transcriptional level in a promoter sequence-specific manner in human cells.

Animals↗
PubMed1985

Anorectic behavior, mood, and metabolic and endocrine adaptation to starvation in anorexia nervosa during inpatient treatment.

Twenty-two patients with anorexia nervosa were studied at 2-week intervals during treatment on psychiatric wards. In order to characterize the metabolic situation in starvation, levels of free fatty acids, beta-hydroxybutyric acid, and acetoacetate were measured. The endocrine adaptation to starvation was studied by measuring triiodothyronine, noradrenaline, and cortisol. Anorectic symptoms were assessed by the Anorexia Nervosa Inventory Scale (ANIS) and mood changes on the basis of a "Befindlichkeits" Scale (BF). Only half of the patients showed metabolic and endocrine signs of starvation on admission to the hospital, despite low body weight. This group had significantly more severe anorectic symptoms (ANIS) and gained weight at a lesser rate. Metabolic signs of starvation disappeared during the first 4 weeks of therapy in most of the patients. The endocrine indicators for starvation normalized much more slowly, with noradrenaline having the slowest pace. "Bulimics" and "restricters" could not be distinguished from one another by metabolic or endocrine observations. The "bulimics," however, showed more severe anorectic symptoms (ANIS) and a more depressed mood.

Adolescent↗
PubMed2006

Neoplastic transformation of human diploid fibroblasts after long-term serum starvation.

Serum starvation for several days has been considered as a positive effect on the efficiency of nuclear transfer using donor cells. The effects of longer period serum starvation are not clear while similar starvation might occur in vitro maintained cells (i.e. tissue engineering products) and in vivo such as ischemia of human tissues or organs. We found human dermis fibroblasts were transformed for about 70 days caused by serum starvation (0.5% serum). The transformed cells became round and had more than one nucleolus. In 0.5% serum medium they kept almost constant growth rate as the normal fibroblasts in 10% serum medium. Abnormal karyotype including aneuploidy and structural aberrations was observed. The transformed cells had high telomerase activities, in contrast, normal fibroblasts had no detectable telomerase activities. C-myc was up-regulated while cdk2, cyclin A, p21 were down in transformed cells. Cell transplantation into SCID nude mice confirmed that the cells had the capacity of forming solid tumors. The results indicated that long-term serum starvation could lead to cell chromosomal instability and transformation.

Animals↗
PubMed2006

Stage-dependent effects of starvation on the growth, metamorphosis, and ecdysteroidogenesis by the prothoracic glands during the last larval instar of the silkworm, Bombyx mori.

The stage-dependent effects of starvation on the growth, metamorphosis, and ecdysteroidogenesis of the prothoracic glands during the last larval instar of the silkworm, Bombyx mori, were studied in the present study. When last instar larvae were starved beginning on day 1 of that instar, all larvae died between days 5 and 7 of the instar. Although the prothoracicotropic hormone (PTTH) release from the brain-corpus cardiacum-corpus allatum (BR-CC-CA) did not significantly change during starvation, a deficiency in PTTH signal transduction was maintained, which led to very low levels of hemolymph ecdysteroids after the beginning of starvation. However, when starvation began on day 3 of the last larval instar, the major hemolymph ecdysteroid peak, preceding larval-pupal transformation, occurred 1 day earlier than that in control larvae. Protein content of the prothoracic glands in day 3-starved larvae was maintained at a low level as compared to that of control larvae. The secretory activity of the prothoracic glands in day 3-starved larvae was maintained at a level similar to that of control larvae. However, the rate of ecdysteroidogenesis, expressed per microgram of glandular protein, was greatly enhanced in these starved larvae, indicating that upon starvation, larvae increased the ecdysteroid production rate to enhance the rate of survival.

Animals↗
PubMed2006

Endogenous processes during long-term starvation in activated sludge performing enhanced biological phosphorus removal.

In many biological wastewater treatment systems, bacterial growth and the amount of active biomass are limited by the availability of substrate. Under these low growth conditions, endogenous processes have a significant influence on the amount of active biomass and therefore, the overall system performance. In enhanced biological phosphorus removal (EBPR) systems endogenous processes can also influence the levels of the internal storage compounds of the polyphosphate accumulating organisms (PAO), directly affecting phosphorus removal performance. The purpose of this study was to evaluate the significance of different endogenous processes that occur during the long-term starvation of EBPR sludge under aerobic and anaerobic conditions. Activated sludge obtained from a laboratory sequencing batch reactor was used to perform a series of batch starvation experiments. Under aerobic starvation conditions we observed a significant decay of PAO (first-order decay rate of 0.15/d) together with a rapid utilization of polyhydroxyalkanoates (PHA) and a slower utilization of glycogen and polyphosphate to generate maintenance energy. On the other hand, anaerobic starvation was best described by maintenance processes that rapidly reduce the levels of polyphosphate and glycogen under starvation conditions while no significant decay of PAO was observed. The endogenous utilization of glycogen for maintenance purposes is currently not included in available EBPR models. Our experimental results suggest that mathematical models for in EBPR should differentiate between aerobic and anaerobic endogenous processes, as they influence active biomass and storage products differently.

Aerobiosis↗
PubMed2001

Effects of the duration and timing of starvation during larval life on the metamorphosis and initial juvenile size of the polychaete Hydroides elegans (Haswell).

The larvae of the polychaete Hydroides elegans were exposed to different feeding schedules to evaluate the effects of starvation on metamorphosis and initial juvenile volume. The timing of starvation (early or late in development) and the total number of days of feeding (3, 5 or 8 days) at 24 degrees C had significant effects on the percentage of larvae that successfully completed metamorphosis and on the volume of the post-metamorphic juveniles. However, the duration of starvation (2, 4, 6 or 8 days) did not influence metamorphosis or juvenile volume. For larvae that had fed for 3 or 5 days, those that were starved at the beginning of development had a higher percentage of successful metamorphosis and produced larger juveniles compared with those starved after an initial 3-day feeding period. Larvae that had been allowed to feed for a total of 8 days were not affected by the timing of starvation. The percentage metamorphosis was lower in larvae that had fed for 3 days (16%), but was not significantly different between those that fed for 5 days (47%) compared to 8 days (47%). However, juvenile volume increased with the number of days of feeding from 0.95 nl after 3 days to 1.35 nl after 5 days, to 1.91 nl after 8 days of feeding. Discontinuous feeding reduced the proportion of larvae undergoing metamorphosis and juvenile volume compared to larvae continuously fed for only 5 days, but had no effect on larvae that fed for 8 days. The larvae of this extremely successful fouling species are remarkably tolerant of starvation and seem to require approximately 5 days of continuous feeding to achieve high levels of metamorphic success and large initial juvenile volume.

Journal Article↗
PubMed1999

Starvation-associated mutagenesis in yeast Saccharomyces cerevisiae is affected by Ras2/cAMP signaling pathway.

The number of revertants with restored ability to form colony increases in a time-dependent manner during long-term selective starvation of dense mutant microbial cultures. This is due to starvation-associated (also called adaptive) mutations that arise in a replication independent manner. Here we report that in Saccharomyces cerevisiae the frequency of starvation-associated reversions of mutant genes whose products are necessary for amino acids biosynthesis are influenced by Ras2/cAMP signaling pathway. This signaling pathway is a yeast general regulatory pathway involved in nutritional sensing, UV response, sporulation control and life span control and its changes are manifested in both, cell cycle and life cycle. Inactivation of the RAS2 gene causes an increase in number of starvation-associated revertants in comparison to an isogenic wild type strain and a strain with constitutively activated Ras2/cAMP signaling pathway. Therefore, we suggest that starvation-associated mutagenesis is different from spontaneous mutagenesis and is related to the cellular capacity to adopt distinct physiological states in response to environmental signals.

Culture Media↗
PubMed2003

Glutamine starvation of monocytes inhibits the ubiquitin-proteasome proteolytic pathway.

Peripheral blood monocytes utilize free glutamine (Gln) in addition to glucose as an important energy substrate. Although this demand increases upon activation, monocytes are commonly confronted with decreased plasma Gln during critical illness and thus suffer from Gln-starvation. Here we investigate the influence of Gln-starvation on protein stability and its effects on the monocyte proteome. Gln-starvation caused a reduction of protein degradation which was accompanied by an accumulation of ubiquitin-protein conjugates and a reduction of intracellular ATP. Similar effects were observed under ATP-reducing conditions and in the presence of a proteasome inhibitor. Using two-dimensional gel electrophoresis we identified the IL-1beta precursor protein (pIL-1beta) as the, by far, most induced protein in endotoxin-treated monocytes. The degradation of the short-lived pIL-1beta was strongly reduced during Gln-starvation, while the degradation of the long-lived, constitutively expressed beta-actin was less affected. This indicates that although Gln-starvation reduces protein breakdown on the overall proteasome level, it leads to differential changes in the stability of specific proteins. This selective effect is likely to contribute to the immunocompromised state of monocytes commonly observed during critical illness.

Actins↗
PubMedDate not supplied

Starvation alters the activity and mRNA level of glutaminase and glutamine synthetase in the rat intestine.

The metabolism of glutamine, the main respiratory fuel of enterocytes, is governed by the activity of glutaminase and glutamine synthetase. Because starvation induces intestinal atrophy, it might alter the rate of intestinal glutamine utilization. This study examined the effect of starvation on the activity, level of mRNA, and distribution of mRNA of glutaminase and glutamine synthetase in the rat intestine. Rats were randomized into groups and were either: (1) fed for 2 days with rat food ad libitum or (2) starved for 2 days. Standardized segments of jejunum and ileum were removed for the estimation of enzyme activity, level of mRNA, and in situ hybridization analysis. The jejunum of the fed rats had a greater activity of both enzymes per centimeter of intestine (P < 0.01), a greater glutaminase specific activity (1.97 +/- 0.45 vs. 1.09 +/- 0.34 micromol/hr/mg protein, P < 0.01), and a lower level of glutaminase and glutamine synthetase mRNA. The ileum of the fed rats had a greater activity of glutamine synthetase per centimeter of intestine (162.9 +/- 50.6 vs. 91.0 +/- 23.1 nmol/hr/cm bowel, P < 0.01), a lower level of glutaminase mRNA, and a greater level of glutamine synthetase mRNA. In situ hybridization analysis showed that starvation does not alter the distribution of glutaminase and glutamine synthetase mRNA in the intestinal mucosa. This study confirms that starvation decreases the total intestinal activity per centimeter of both glutaminase and glutamine synthetase. More importantly, the results indicate that the intestine adapts to starvation by accumulating glutaminase mRNA. This process prepares the intestine for a restoration of intake.

Journal Article↗
PubMed2002

Effect of starvation on the performance and re-acclimation of biotrickling filters for air pollution control.

Biotrickling filters for air pollution control are expected to encounter fluctuating conditions or periods without pollutant supply. In the present study, we investigated the effect of pollutant starvation in bench-scale biotrickling filters treating toluene. The experimental protocol consisted of starving biotrickling filters under various conditions: with or without airflow, with or without liquid recycle, and with or without an alternate carbon source (glucose) supply. The duration of the period without toluene was varied from 2 to 9 days, during time which the biotrickling filters were monitored for biomass content, endogenous and toluene-induced oxygen uptake rates during starvation, and toluene overall elimination capacity after restart. During starvation, all reactors lost their ability to degrade toluene within 5 days, regardless of the mode of starvation. The biomass content significantly decreased during starvation, in particular in those reactors where the recycle liquid was maintained, but this decrease was not critical for future re-acclimation. Glucose addition to starved biotrickling filters had several detrimental effects. It resulted in a faster decrease of the biomass content and slowed the reacclimation phase. Overall, the results show that the reacclimation of toluene-degrading biotrickling filters after periods of nonuse is short (10-24 h to re-establish full performance), and they suggest that, in the case of toluene-degrading biotrickling filters, re-acclimation time is largely governed by the induction of key pollutant-degrading enzymes.

Air Pollution↗
PubMed1991

Glucose starvation and acidosis: effect on experimental metastatic potential, DNA content and MTX resistance of murine tumour cells.

Exposure to oxygen deprivation in vitro has been reported to cause drug resistance in CHO cells (Rice et al., 1986; PNAS 83, 5978) and enhancement of experimental metastatic (colonisation) ability of murine tumour cells (Young et al., 1988; PNAS 85, 9533). Both these studies also demonstrated the induction of a subpopulation of cells with excess DNA content. Since the micromilieu in tumours results in exposure of the tumour cells to conditions of acid pH and nutrient deprivation, as well as hypoxia, we have examined the effect of exposure to acidosis (pH 6.5) and glucose starvation on drug resistance, cellular DNA content and the experimental metastatic ability of KHT sarcoma and B16F1 melanoma cells. Cells were exposed to these conditions for 24 and 48 h and tested for resistance to methotrexate (MTX) or experimental metastatic ability either immediately following these exposures or after 24 or 48 h of recovery in normal growth medium. Both cell lines demonstrated an enhancement of colonisation potential, which was most marked when cells were injected after 48 h of exposure followed by a 24 or 48 h recovery period. Flow cytometric analysis demonstrated an increase in the fraction of KHT cells with excess DNA following both glucose starvation and acidosis we observed only a small increase in MTX resistance following acidic exposure of cells and no change following glucose starvation. Since both acidosis and glucose starvation are known to induce glucose regulated proteins (grp), a subset of the stress protein family, we studied the effect of treatment with another known inducer, 2-deoxyglucose. We found that this agent affected the metastatic efficiency of KHT cells in a manner similar to that observed following exposure to glucose starvation and acidosis. However, further studies are required to establish what role, if any, grp play in this effect. In conclusion this study shows that transient exposure of murine tumour cells to an acidic or glucose deprived environment can cause progression in terms of metastatic potential.

Acidosis↗
PubMed2005

Selective charging of tRNA isoacceptors induced by amino-acid starvation.

Aminoacylated (charged) transfer RNA isoacceptors read different messenger RNA codons for the same amino acid. The concentration of an isoacceptor and its charged fraction are principal determinants of the translation rate of its codons. A recent theoretical model predicts that amino-acid starvation results in 'selective charging' where the charging levels of some tRNA isoacceptors will be low and those of others will remain high. Here, we developed a microarray for the analysis of charged fractions of tRNAs and measured charging for all Escherichia coli tRNAs before and during leucine, threonine or arginine starvation. Before starvation, most tRNAs were fully charged. During starvation, the isoacceptors in the leucine, threonine or arginine families showed selective charging when cells were starved for their cognate amino acid, directly confirming the theoretical prediction. Codons read by isoacceptors that retain high charging can be used for efficient translation of genes that are essential during amino-acid starvation. Selective charging can explain anomalous patterns of codon usage in the genes for different families of proteins.

Amino Acids↗
PubMed1973

Synthesis and degradation of phosphoenolpyruvate carboxylase in rat liver and adipose tissue. Changes during a starvation-re-feeding cycle.

A specific antibody against liver cytosol phosphoenolpyruvate carboxylase (EC 4.1.1.32) was used to isolate the enzyme from liver and adipose tissue. With this technique we have shown that phosphoenolpyruvate carboxylase synthesis in starved rats accounts for 3% of the total synthesis of cytosol protein in each tissue. Re-feeding starved animals decreases this relative rate of phosphoenolpyruvate carboxylase synthesis to 0.2% and 1% respectively in liver and adipose tissue, and the activity of the enzyme in each tissue is decreased to 25% of the starvation value. An additional starvation period is accompanied by an increased rate of enzyme synthesis, but the response to starvation is considerably slower than that caused by re-feeding. The degradation rate of phosphoenolpyruvate carboxylase is also subject to regulation. Thus re-feeding starved animals decreases the half-life of the enzyme in liver from 13h to 5.2h, but the rapid rate of degradation is maintained at least during the first 20h of subsequent starvation. Only slight changes in the degradation rate of phosphoenolpyruvate carboxylase are found in adipose tissue. We conclude that the large alterations in the rate of enzyme synthesis during a starvation-re-feeding cycle are the major cause of fluctuations in activity.

Journal Article↗
PubMed2002

Mutations at CRE1 impair cytokinin-induced repression of phosphate starvation responses in Arabidopsis.

Plants display a number of responses to low phosphate availability, involving biochemical and developmental changes. Recently we have shown that many of these responses can be repressed in roots by exogenous addition of cytokinins. In order to understand the genetic basis to this effect of cytokinins, and its relation with the better known roles of cytokinins in the control of cell-cycle and differentiation, we have undertaken mutant screening and characterization using a transgenic line of Arabidopsis thaliana harbouring a reporter gene specifically responsive to Pi starvation (AtIPS1::GUS). One type of mutant identified displayed reduced sensitivity of AtIPS1::GUS to cytokinin repression. Several other Pi starvation response genes showed reduced cytokinin sensitivity in these lines. These mutants also showed reduced cytokinin repression of the anthocyanin accumulation induced by Pi starvation in the aerial part of the plants. Mapping and molecular characterization of these mutants showed that they were allelic of CRE1/WOL, a locus known to encode a cytokinin receptor. CRE1 is downregulated by Pi starvation and induced by cytokinins, both in the wild-type and in the cre1 mutants, in which cre1 mRNA levels are higher. These results reveal the existence of a positive feed-back loop, in addition to the already established negative feedback loop, in cytokinin signalling and indicate that the negative regulation of Pi starvation responses by cytokinins involves a two-component signalling circuitry, as it is the case of other types of cytokinin response.

Alleles↗
PubMed1974

Replication of the Escherichia coli chromosome following thymine starvation.

The replication of the chromosome of E. coli 15T(-) (thymine-requiring) has been followed for approximately four generations after a premature initiation of DNA synthesis by thymine starvation. Various labelings of the DNA with (14)C, (3)H, and density media allowed discrimination of the strands preexistent to thymine starvation from those which were made during the subsequent generations. Results were: (1) There is very little, if any, DNA degradation following 45 min of thymine starvation. (2) The growing points which existed prior to thymine starvation proceeded to the end of the chromosomes after resumption of DNA synthesis and then disappeared. (3) The premature DNA synthesis initiated by thymine starvation involved, symmetrically, all free origins; the entire chromosomal population was subjected to this process. (4) All the DNA which was synthesized during the progression of the premature growing points was normally replicated, i.e., with no delay or loss, during the next three generations.

Carbon Radioisotopes↗