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PubMed1970

The effect of diet and acute starvation on the deiodination of thyroxine and triiodothyronine in the thyroidectomized rat.

1. General agreement exists that the level of thyroid function is depressed by starvation. The virtually complete cessation of biliary-faecal thyroxine loss in the starved animal makes the significance of this reduction difficult to assess in physiological terms.2. Deiodination of [(131)I]thyroxine was investigated in thyroidectomized rats. Thus central feed-back effects were eliminated and the changes in peripheral utilization of thyroxine could be observed. The simultaneous use of [(125)I] sodium iodide permitted changes in renal handling of iodide to be taken into consideration.3. Rats fed oxoid (Oxo Ltd. diet 41 B) deiodinated a significantly greater proportion of thyroxine in the 24 hr after injection of a tracer dose of [(131)I]thyroxine than did the starved or glucose-fed rat. [(131)I]triiodothyronine was also probably deiodinated at a faster rate in oxoid-fed rats than in starved or glucose-fed rats.4. Thyroxine was deiodinated at a faster rate by starved rats than by rats fed glucose.5. Thyroxine disappeared significantly faster from the blood in oxoid-fed than in the starved or glucose-fed rat. Thyroxine also disappeared faster from the blood in the starved rat than in the glucose-fed rat over 24 hr.6. These results are discussed in relation to previous findings of depressed pituitary-thyroid function in starvation.

Animals↗
PubMed1971

Regulation of chromosome replication in Bacillus subtilis: marker frequency analysis after amino acid starvation.

Marker frequency analysis of DNA isolated from amino acid-starved Bacillus subtilis cells shows that most chromosomes have not completed replication to the terminus. This finding agrees with earlier results concerning replication after amino acid starvation in this organism. The results are not compatible with regulation of chromosome replication at the initiation step only, and they suggest that a second regulatory circuit controls replication under conditions of amino acid starvation.

Amino Acids↗
PubMed1973

Pyrimidine starvation induced by adenosine in fibroblasts and lymphoid cells: role of adenosine deaminase.

In the presence of 10(-4) to 10(-5) molar adenosine, established cell lines of fibroblastic or lymphoid origin die of pyrimidine starvation. Less than lethal concentrations inhibit cell growth. Over a broad concentration range, the effects of adenosine are prevented by providing a suitable pyrimidine source. We suggest that the recently described immune deficiency disease associated with absence of adenosine deaminase may be the result of pyrimidine starvation induced by adenosine nucleotides in cells of the lymphoid system.

Adenosine↗
PubMed1976

Morphological characterization of small cells resulting from nutrient starvation of a psychrophilic marine vibrio.

Upon starvation, Ant-300, a psychrophilic marine vibrio, was observed to decrease in size and change in shape from a rod to a coccus. After 3 weeks of starvation 50% of the starved population was able to pass through a filter with a pore size of 0.4 mum. Electron microscopy of thin sections of the small cells revealed normal cell structure except for an enlarged periplasmic space. When inoculated into a fresh medium, starved cells growth without a significant lag and regained "normal" size and shape within 48 h.

Arctic Regions↗
PubMed1992

Effect of starvation on induction of quinoline degradation for a subsurface bacterium in a continuous-flow column.

Differences in the induction response and the initial two reactions of quinoline degradation between short-term (2 days)- and long-term (60 to 80 days)-starved cells of a subsurface Pseudomonas cepacia strain were examined by using continuous-flow columns. The ability of bacteria that are indigenous to oligotrophic environments to respond to a contaminant was assessed by using long-term starvation to induce a cell physiology that simulates the in situ physiology of the bacteria. With quinoline concentrations of 39 and 155 muM, long-term-starved cells converted quinoline to degradation products more efficiently than did short-term-starved cells. Quinoline concentrations of 155 muM and, to a greater extent, 775 muM had an inhibitory effect on induction in long-term-starved cells. However, only the length of the induction process was affected with these quinoline concentrations; degradation of quinoline at the steady state for long-term-starved cells was equal to or better than that for short-term-starved cells. The induction time for short-term-starved cells did not increase progressively with increasing quinoline concentration. Experiments with starved cells are important for the development of accurate predictive models of contaminant transport in the subsurface because starvation, which induces a cell physiology that simulates the in situ physiology of many bacteria, may affect the induction process.

Journal Article↗
PubMed1993

Starvation-induced thermal tolerance as a survival mechanism in a psychrophilic marine bacterium.

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.

Journal Article↗
PubMed1995

Flow cytometric assessment of Escherichia coli and Salmonella typhimurium starvation-survival in seawater using rhodamine 123, propidium iodide, and oxonol.

The use of flow cytometry in microbiology allows rapid characterization of cells from a nonhomogeneous population. A method based on flow cytometry to assess the effects of lethal agents and the bacterial survival in starved cultures through the use of membrane potential-sensitive dyes and a nucleic acid marker is presented. The use of propidium iodide, rhodamine, and oxonol has facilitated the differentiation of cells of Escherichia coli and Salmonella typhimurium of various states of vitality following various treatments (heat, sonication, electroporation, and incubation with gramicidin) and during starvation in artificial seawater. The fluorescence intensity is directly correlated with viable cell counts for rhodamine 123 labelling, whereas oxonol and propidium iodide labelling is inversely correlated with viable counts. The distribution of rhodamine and oxonol uptake during starvation-survival clearly indicates that single-species starved bacteria are heterogeneous populations, and flow cytometry can be a fundamental tool for quantifying this heterogeneity.

Escherichia coli↗
PubMed1998

An immunological strategy To monitor In situ the phosphate starvation state in thiobacillus ferrooxidans

Thiobacillus ferrooxidans is one of the chemolithoautotrophic bacteria important in industrial biomining operations. During the process of ore bioleaching, the microorganisms are subjected to several stressing conditions, including the lack of some essential nutrients, which can affect the rates and yields of bioleaching. When T. ferrooxidans is starved for phosphate, the cells respond by inducing the synthesis of several proteins, some of which are outer membrane proteins of high molecular weight (70,000 to 80,000). These proteins were considered to be potential markers of the phosphate starvation state of these microorganisms. We developed a single-cell immunofluorescence assay that allowed monitoring of the phosphate starvation condition of this biomining microorganism by measuring the increased expression of the surface proteins. In the presence of low levels of arsenate (2 mM), the growth of phosphate-starved T. ferrooxidans cells was greatly inhibited compared to that of control nonstarved cells. Therefore, the determination of the phosphorus nutritional state is particularly relevant when arsenic compounds are solubilized during the bioleaching of different ores.

Journal Article↗
PubMed1999

Escherichia coli resistance to chlorine and glutathione synthesis in response to oxygenation and starvation.

Reduced glutathione (GSH) levels and resistance to chlorine were measured for two isogenic Escherichia coli strains stressed by oxygenation and/or starvation. The E. coli mutant deficient in GSH was not more sensitive to the oxidant than its parent strain when the bacteria were cultured with a low oxygenation rate. Starvation or oxygenation increased the resistance of the parent strain to chlorine, while the resistance of the deficient strain remained unchanged.

Aerobiosis↗
PubMed1999

Influence of carbohydrate starvation and arginine on culturability and amino acid utilization of lactococcus lactis subsp. lactis.

Two strains of Lactococcus lactis subsp. lactis were used to determine the influence of lactose and arginine on viability and amino acid use during carbohydrate starvation. Lactose provided energy for logarithmic-phase growth, and amino acids such as arginine provided energy after carbohydrate exhaustion. Survival time, cell numbers, and ATP concentrations increased with the addition of arginine to the basal medium. By the onset of lactose exhaustion, the concentrations of glycine-valine and glutamate had decreased by as much as 67% in L. lactis ML3, whereas the serine concentration increased by 97% during the same period. When no lactose was added, the concentrations of these amino acids remained constant. Similar trends were observed for L. lactis 11454. Without lactose or arginine, L. lactis ML3 was nonculturable on agar but was viable after 2 days, as measured by fluorescent viability stains and intracellular ATP levels. However, L. lactis 11454 without lactose or arginine remained culturable for at least 14 days. These data suggest that lactococci become viable but nonculturable in response to carbohydrate depletion. Additionally, these data indicate that amino acids other than arginine facilitate the survival of L. lactis during carbohydrate starvation.

Journal Article↗
PubMed2000

Effect of starvation and the viable-but-nonculturable state on green fluorescent protein (GFP) fluorescence in GFP-tagged Pseudomonas fluorescens A506.

The green fluorescent protein (GFP) gene, gfp, of the jellyfish Aequorea victoria is being used as a reporter system for gene expression and as a marker for tracking prokaryotes and eukaryotes. Cells that have been genetically altered with the gfp gene produce a protein that fluoresces when it is excited by UV light. This unique phenotype allows gfp-tagged cells to be specifically monitored by nondestructive means. In this study we determined whether a gfp-tagged strain of Pseudomonas fluorescens continued to fluoresce under conditions under which the cells were starved, viable but nonculturable (VBNC), or dead. Epifluorescent microscopy, flow cytometry, and spectrofluorometry were used to measure fluorescence intensity in starved, VBNC, and dead or dying cells. Results obtained by using flow cytometry indicated that microcosms containing VBNC cells, which were obtained by incubation under stress conditions (starvation at 37.5 degrees C), fluoresced at an intensity that was at least 80% of the intensity of nonstressed cultures. Similarly, microcosms containing starved cells incubated at 5 and 30 degrees C had fluorescence intensities that were 90 to 110% of the intensity of nonstressed cells. VBNC cells remained fluorescent during the entire 6-month incubation period. In addition, cells starved at 5 or 30 degrees C remained fluorescent for at least 11 months. Treatment of the cells with UV light or incubation at 39 or 50 degrees C resulted in a loss of GFP from the cells. There was a strong correlation between cell death and leakage of GFP from the cells, although the extent of leakage varied depending on the treatment. Most dead cells were not GFP fluorescent, but a small proportion of the dead cells retained some GFP at a lower concentration than the concentration in live cells. Our results suggest that gfp-tagged cells remain fluorescent following starvation and entry into the VBNC state but that fluorescence is lost when the cells die, presumably because membrane integrity is lost.

Colony Count, Microbial↗
PubMed2001

Role of sigma(B) in heat, ethanol, acid, and oxidative stress resistance and during carbon starvation in Listeria monocytogenes.

To determine the contribution of sigma B (sigma(B)) to survival of stationary-phase Listeria monocytogenes cells following exposure to environmental stresses, we compared the viability of strain 10403S with that of an isogenic nonpolar sigB null mutant strain after exposure to heat (50 degrees C), ethanol (16.5%), or acid (pH 2.5). Strain viabilities were also determined under the same conditions in cultures that had been previously exposed to sublethal levels of the same stresses (45 degrees C, 5% ethanol, or pH 4.5). The DeltasigB and wild-type strains had similar viabilities following exposure to ethanol and heat, but the DeltasigB strain was almost 10,000-fold more susceptible to lethal acid stress than its parent strain. However, a 1-h preexposure to pH 4.5 yielded a 1,000-fold improvement in viability for the DeltasigB strain. These results suggest the existence in L. monocytogenes of both a sigma(B)-dependent mechanism and a pH-dependent mechanism for acid resistance in the stationary phase. sigma(B) contributed to resistance to both oxidative stress and carbon starvation in L. monocytogenes. The DeltasigB strain was 100-fold more sensitive to 13.8 mM cumene hydroperoxide than the wild-type strain. Following glucose depletion, the DeltasigB strain lost viability more rapidly than the parent strain. sigma(B) contributions to viability during carbon starvation and to acid resistance and oxidative stress resistance support the hypothesis that sigma(B) plays a role in protecting L. monocytogenes against environmental adversities.

Adaptation, Physiological↗
PubMed2001

Survival response and rearrangement of plasmid DNA of Lactococcus lactis during long-term starvation.

The survival response of Lactococcus lactis during long-term starvation was investigated. The cells were cultured with different levels of glucose (the sole energy source) and either were kept in the resultant spent medium or transferred to fresh medium (without glucose) for up to 2 years. The survival of the cells during starvation was not dependent on the nature of transition phase, as expected, but on the nature of medium in which the cells were kept. The proliferation of cells, despite the apparent lack of glucose, could have been due to some cells being able to utilize the small amounts of peptides still present in the spent medium or to use energy sources provided by the breakup of dead cells. The 1- and 2-year-old cultures contained cells with vastly changed morphotypes. When these isolates were examined, it was revealed that the original plasmids present in the parent were rearranged in a certain way, and an entirely new plasmid was generated. Changes were also evident in the chromosomal DNA and in gene expression. Furthermore, all of the isolates exhibited a growth advantage relative to the parent cells when grown in energy-limiting media. When they were tested against different types of stresses, they exhibited a higher resistance against the bile salt and hydrogen peroxide stresses compared to the parent. Because of the similar changes observed in the 2-year-old isolates, a similar survival strategy may be operational in those cells that survive for that length of time.

Bacterial Proteins↗
PubMed2004

Insights into the survival of Chlamydomonas reinhardtii during sulfur starvation based on microarray analysis of gene expression.

Responses of photosynthetic organisms to sulfur starvation include (i) increasing the capacity of the cell for transporting and/or assimilating exogenous sulfate, (ii) restructuring cellular features to conserve sulfur resources, and (iii) modulating metabolic processes and rates of cell growth and division. We used microarray analyses to obtain a genome-level view of changes in mRNA abundances in the green alga Chlamydomonas reinhardtii during sulfur starvation. The work confirms and extends upon previous findings showing that sulfur deprivation elicits changes in levels of transcripts for proteins that help scavenge sulfate and economize on the use of sulfur resources. Changes in levels of transcripts encoding members of the light-harvesting polypeptide family, such as LhcSR2, suggest restructuring of the photosynthetic apparatus during sulfur deprivation. There are also significant changes in levels of transcripts encoding enzymes involved in metabolic processes (e.g., carbon metabolism), intracellular proteolysis, and the amelioration of oxidative damage; a marked and sustained increase in mRNAs for a putative vanadium chloroperoxidase and a peroxiredoxin may help prolong survival of C. reinhardtii during sulfur deprivation. Furthermore, many of the sulfur stress-regulated transcripts (encoding polypeptides associated with sulfate uptake and assimilation, oxidative stress, and photosynthetic function) are not properly regulated in the sac1 mutant of C. reinhardtii, a strain that dies much more rapidly than parental cells during sulfur deprivation. Interestingly, sulfur stress elicits dramatic changes in levels of transcripts encoding putative chloroplast-localized chaperones in the sac1 mutant but not in the parental strain. These results suggest various strategies used by photosynthetic organisms during acclimation to nutrient-limited growth.

Animals↗
PubMed2004

PheP, a putative amino acid permease of Staphylococcus aureus, contributes to survival in vivo and during starvation.

PheP, a putative amino acid permease in Staphylococcus aureus, contributes to starvation survival under glucose-limiting conditions and virulence. A pheP mutation led to poor growth after microaerobic or anaerobic incubation on pig serum agar, which was recovered by phenylalanine addition. Genetic complementation of pheP restored growth and starvation survival.

Amino Acid Transport Systems↗
PubMed1969

Influence of carbon or nitrogen starvation on amino acid transport in Pseudomonas aeruginosa.

Pseudomonas aeruginosa was shown to utilize the majority of commonly occurring amino acids for growth as either the sole carbon or the sole nitrogen source. During carbon or nitrogen deprivation, the rates of transport of most of the amino acids remained unchanged; however, the transport rates for glutamate, alanine, and glycine increased under these conditions and the transport rates for leucine and valine decreased. Normal transport rates for these amino acids were resumed immediately upon the addition of the required nutrient. In the absence of an external source of carbon or of nitrogen, pool amino acids underwent rapid degradation. (14)C-Amino acid pulse experiments indicated that the constitutive amino acid catabolic enzymes, normally present in the organism during growth with glucose as the carbon source, were responsible for rapid pool losses. Nutrient starvation in the presence of chloramphenicol did not prevent amino acid catabolism. This enzymic activity is interpreted as providing P. aeruginosa with a selective advantage for survival during conditions of carbon or nitrogen starvation.

Alanine↗
PubMed1970

Regulation of ribonucleic acid synthesis by histidine and methionine during recovery of Escherichia coli from magnesium starvation.

During magnesium starvation of Escherichia coli B, most of the ribosomes break down to low-molecular-weight components. When magnesium is restored to the medium, the cells recover. The rate of recovery can be increased greatly by supplementing the growth medium with a mixture of 21 amino acids. This increased rate of recovery is shown to be due to the effect of only two amino acids, histidine and methionine, which initially stimulate accumulation of cellular ribonucleic acid without increasing the rate of protein synthesis. In contrast, histidine and methionine supplementation to logarithmically growing E. coli B is not as effective in stimulating growth as is the complete amino acid mixture. Since cells recovering from magnesium starvation preferentially synthesize ribosomes, it is possible that histidine and methionine play a special role(s) in ribosomal ribonucleic acid synthesis or stability.

Amino Acids↗
PubMed1971

Influence of thymine starvation on the integrity of deoxyribonucleic acid in Escherichia coli.

The influence of thymine starvation on the single-strand molecular weight of deoxyribonucleic acid (DNA) from Escherichia coli was determined by sedimentation through gradients of alkaline sucrose. Growth of cells for as long as 150 min in thymineless medium did not significantly reduce the molecular weight below the control value of 2.4 +/- 0.3 x 10(8) daltons. Incubation of cells in thymineless medium after exposure to 500 ergs/mm(2) of ultraviolet light or 20 krad of (137)Cs gamma rays did not appear to block the rejoining of single-strand breaks associated with irradiation. Thus, DNA repair enzymes, presumably including DNA ligase, are not significantly inhibited by thymine starvation.

Carbon Isotopes↗