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

Vibrio parahaemolyticus is known to exist in a viable but nonculturable state when incubated at low temperature under starvation. It has long been debated whether the culturable cells which appear after temperature upshift are the result of true resuscitation or regrowth of a few residual culturable cells. Starved V. parahaemolyticus cells at 4 degrees C reached the nonculturable stage in about 12 days. The true resuscitation of nonculturable cells of V. parahaemolyticus occurred after spreading them onto an agar medium supplemented with H(2)O(2)-degrading compounds such as catalase or sodium pyruvate. The proposed method may be applicable to detecting the enteropathogen from environmental samples.
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PMID:Resuscitation of viable but nonculturable cells of Vibrio parahaemolyticus induced at low temperature under starvation. 1077 22

Toxoplasma gondii is an obligate intracellular parasite that is a common opportunistic pathogen of the central nervous system in AIDS patients. Gamma interferon (IFN-gamma) alone or in combination with interleukin-1 (IL-1), IL-6, or tumor necrosis factor alpha significantly inhibits the growth of T. gondii in murine astrocytes, suggesting these are important nonimmune effector cells in the brain. Inhibition was found to be independent of a nitric oxide-mediated or tryptophan starvation mechanism. Both reactive oxygen intermediates and iron deprivation are IFN-gamma-mediated mechanisms known to operate against intracellular parasites in other cell types. Astrocytes generated from mice genetically deficient in the production of reactive oxygen intermediates (phox(-/-) mice) were found to inhibit growth of T. gondii when stimulated with IFN-gamma alone or in combination with other cytokines. The reactive oxygen inhibitor catalase and the reactive oxygen scavengers mannitol and thiourea failed to reverse the IFN-gamma-induced inhibition of T. gondii in astrocytes. These data indicate that IFN-gamma-induced inhibition in astrocytes is independent of reactive oxygen intermediates. IFN-gamma-induced inhibition could not be reversed by the addition of iron salts, ferric citrate, ferric nitrate, or ferric transferrin. Pretreatment of astrocytes with desferrioxamine also did not induce the inhibition of T. gondii. These data indicate that the mechanism of IFN-gamma inhibition was not due to iron deprivation. IFN-gamma had no effect on T. gondii invasion of astrocytes, but inhibition of growth and loss of tachyzoite vacuoles were evident in IFN-gamma-treated astrocytes by 24 h after invasion. Overall, these data suggest that IFN-gamma-activated astrocytes inhibit T. gondii by an as-yet-unknown mechanism.
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PMID:Investigation into the mechanism of gamma interferon-mediated inhibition of Toxoplasma gondii in murine astrocytes. 1081 94

Legionella pneumophila, the causative organism of Legionnaires' pneumonia, contains two enzymes with catalatic and peroxidatic activity, KatA and KatB. To address the issue of redundant, overlapping, or discrete in vivo functions of highly homologous catalase-peroxidases, the gene for katA was cloned and its function was studied in L. pneumophila and Escherichia coli and compared with prior studies of katB in this laboratory. katA is induced during exponential growth and is the predominant peroxidase in stationary phase. When katA is inactivated, L. pneumophila is more sensitive to exogenous hydrogen peroxide and less virulent in the THP-1 macrophage cell line, similar to katB. Catalatic-peroxidatic activity with different peroxidatic cosubstrates is comparable for KatA and KatB, but KatA is five times more active towards dianisidine. In contrast with these examples of redundant or overlapping function, stationary-phase survival is decreased by 100- to 10,000-fold when katA is inactivated, while no change from wild type is seen for the katB null. The principal clue for understanding this discrete in vivo function was the demonstration that KatA is periplasmic and KatB is cytosolic. This stationary-phase phenotype suggests that targets sensitive to hydrogen peroxide are present outside the cytosol in stationary phase or that the peroxidatic activity of KatA is critical for stationary-phase redox reactions in the periplasm, perhaps disulfide bond formation. Since starvation-induced stationary phase is a prerequisite to acquisition of virulence by L. pneumophila, further studies on the function and regulation of katA in stationary phase may give insights on the mechanisms of infectivity of this pathogen.
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PMID:Catalase-peroxidases of Legionella pneumophila: cloning of the katA gene and studies of KatA function. 1107 12

Detoxification of hydrogen peroxide is a fundamental aspect of the cellular antioxidant responses in which catalases play a major role. Two differentially regulated catalase genes, catA and catB, have been studied in Aspergillus nidulans. Here we have characterized a third catalase gene, designated catC, which predicts a 475-amino-acid polypeptide containing a peroxisome-targeting signal. With a molecular mass of 54 kDa, CatC shows high similarity to other small-subunit monofunctional catalases and is most closely related to catalases from other fungi, Archaea, and animals. In contrast, the CatA (approximately 84 kDa) and CatB (approximately 79 kDa) enzymes belong to a family of large-subunit catalases, constituting a unique fungal and bacterial group. The catC gene displayed a relatively constant pattern of expression, not being induced by oxidative or other types of stress. Targeted disruption of catC eliminated a constitutive catalase activity not detected previously in zymogram gels. However, a catalase activity detected in catA catB mutant strains during late stationary phase was still present in catC and catABC null mutants, thus demonstrating the presence of a fourth catalase, here named catalase D (CatD). Neither catC nor catABC triple mutants showed any developmental defect, and both mutants grew as well as wild-type strains in H(2)O(2)-generating substrates, such as fatty acids, and/or purines as the sole carbon and nitrogen sources, respectively. CatD activity was induced during late stationary phase by glucose starvation, high temperature, and, to a lesser extent, H(2)O(2) treatment. The existence of at least four differentially regulated catalases indicates a large and regulated capability for H(2)O(2) detoxification in filamentous fungi.
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PMID:Multiple catalase genes are differentially regulated in Aspergillus nidulans. 1115 57

The purpose of this study was to understand the nature of the biochemical and physiological variations between genetically different lines of Drosophila melanogaster. Selection for early or delayed reproduction has given rise to lines with substantial and heritable differences in longevity. The hypotheses tested were that either: (i) a compensatory slowing of metabolism, (ii) increased antioxidative enzyme activities, or (iii) elevated resistance to stressful conditions underlie these differences in longevity. The metabolic rate, metabolic potential (i.e. total amount of oxygen consumed during average lifespan) and speed of walking were all greater in long-lived than in short-lived flies, but there was no enhancement of antioxidant defenses. In fact, catalase activity was significantly lower in the long-lived flies. Long life was largely maintained under heat stress and starvation conditions, and was maintained to a lesser extent upon exposure to paraquat, a superoxide radical generator. In contrast, the 'short-lived' flies had a longer lifespan under cold stress and hyperoxia, also an inducer of radical generation. These results contradict the first two hypotheses and suggest that alleles underlying either long or short life are linked with enhanced resistance to specific kinds of stress, which may account for the preservation of these alleles in the parental population.
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PMID:Antioxidant status and stress resistance in long- and short-lived lines of Drosophila melanogaster. 1125 Jan 17

The Staphylococcus aureus genome encodes three ferric uptake regulator (Fur) homologues: Fur, PerR, and Zur. To determine the exact role of PerR, we inactivated the gene by allelic replacement using a kanamycin cassette, creating strain MJH001 (perR). PerR was found to control transcription of the genes encoding the oxidative stress resistance proteins catalase (KatA), alkyl hydroperoxide reductase (AhpCF), bacterioferritin comigratory protein (Bcp), and thioredoxin reductase (TrxB). Furthermore, PerR regulates transcription of the genes encoding the iron storage proteins ferritin (Ftn) and the ferritin-like Dps homologue, MrgA. Transcription of perR was autoregulated, and PerR repressed transcription of the iron homeostasis regulator Fur, which is a positive regulator of catalase expression. PerR functions as a manganese-dependent, transcriptional repressor of the identified regulon. Elevated iron concentrations produced induction of the PerR regulon. PerR may act as a peroxide sensor, since addition of external hydrogen peroxide to 8325-4 (wild type) resulted in increased transcription of most of the PerR regulon, except for fur and perR itself. The PerR-regulated katA gene encodes the sole catalase of S. aureus, which is an important starvation survival determinant but is surprisingly not required for pathogenicity in a murine skin abscess model of infection. In contrast, PerR is not necessary for starvation survival but is required for full virulence (P < 0.005) in this model of infection. PerR of S. aureus may act as a redox sentinel protein during infection, analogous to the in vitro activities of OxyR and PerR of Escherichia coli and Bacillus subtilis, respectively. However, it differs in its response to the metal balance within the cell and has the added capability of regulating iron uptake and storage.
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PMID:PerR controls oxidative stress resistance and iron storage proteins and is required for virulence in Staphylococcus aureus. 1134 39

Escherichia coli O157:H7 (strains ATCC 43895 and FO46) became nonculturable in sterile, distilled, deionized water or after exposure to chlorine. Recovery of nonculturable E. coli O157:H7 was examined by in vitro and in vivo methods. The decline in culturability of starved E. coli O157:H7 was measured by plate count on rich medium. Recovery in vitro of nonculturable cells was conducted with media amended with catalase or sodium pyruvate; however, there was no apparent increase over culturable cell counts on amended versus nonamended media. Although nonculturable E. coli O157:H7 did not recover under in vitro conditions, a mouse model was used to determine if in vivo conditions would provide sufficient conditions for recovery of nonculturable E. coli O157:H7. In separate studies, mice were orally challenged with starvation-induced nonculturable cells (FO46) or chlorine-induced nonculturable cells (43895 and FO46). Passage through the mouse gastrointestinal tract had no effect on recovery of nonculturable (starvation or chlorine induced) E. coli O157:H7 (43895 or FO46), based on analysis of fecal samples. Mouse kidneys were assayed for the presence of Shiga toxin using the Vero cell assay. Differences in cytotoxicity towards Vero cells from kidney samples of mice receiving nonculturable cells and control mice were not significant, suggesting a loss of virulence.
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PMID:Examination of recovery in vitro and in vivo of nonculturable Escherichia coli O157:H7. 1152 87

Under conditions of low iron availability, most fungi excrete siderophores in order to mobilize extracellular iron. We show that lack of the GATA-type transcription factor SREA in Aspergillus nidulans not only leads to derepression of siderophore biosynthesis but also to deregulation of siderophore-bound iron uptake and ornithine esterase expression. Furthermore, SREA deficiency causes increased accumulation of ferricrocin, the siderophore responsible for intracellular iron storage. In sreA deletion strains, extracellular siderophore production is derepressed but still regulated negatively by iron availability, indicating the presence of an additional iron-regulatory mechanism. In contrast, iron affects ferricrocin accumulation in a positive way, suggesting a protective role for this siderophore in detoxification of intracellular iron excess. The harmfulness of deregulated iron uptake in this mutant is demonstrated by increased expression of genes encoding the antioxidative enzymes catalase CATB and the superoxide dismutases SODA and SODB. It is noteworthy that iron starvation was found to repress catB expression in wild-type (wt) and SREA-deficient strains, consistent with catB being subject to SREA-independent iron regulation. Differential display led to the identification of putative SREA target genes amcA and mirA. The deduced MIRA amino acid sequence displays significant similarity to recently characterized siderophore permeases of Saccharomyces cerevisiae. amcA encodes a putative mitochondrial carrier for the siderophore precursor ornithine, indicating cross-regulation of siderophore and ornithine metabolism.
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PMID:SREA is involved in regulation of siderophore biosynthesis, utilization and uptake in Aspergillus nidulans. 1155 88

Inorganic polyphosphate is a ubiquitous, linear polymer of phosphate residues linked by high-energy phosphoanhydride bonds. In response to starvation, polyP levels are increased up to 100-fold. It has been proposed that chelation of transition metals by polyP might reduce their toxicity, and that polyP accumulation is vital for survival in stationary phase. SOD-deficient E. coli is unable to survive in stationary phase. We found that deletion of the cytoplasmic SODs does not impair the cell's capability of synthesizing polyP. However, transient accumulation of polyphosphate correlated with increased resistance to H(2)O(2) and protection of DNA against oxidative damage. The reason for this protective effect of polyP is the induction of HPII catalase and DNA repair enzymes as members of the rpoS regulon. PolyP did not directly protect DNA against oxidative damage in vitro and acted as a pro-oxidant by stimulating the production of hydroxyl radical in the Fenton reaction. It is thus suggested that accumulation of poly P and rpoS induction cannot compensate for the lack of cytosolic SODs for survival in stationary phase.
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PMID:Polyphosphate accumulation and oxidative DNA damage in superoxide dismutase-deficient Escherichia coli. 1172 6

To date, there is scarce information on the metabolic and biochemical repercussions of Zn-deficiency in fish. In this work, the effect of dietary Zn-deficiency on the diet utilization and the metabolism of activated oxygen species in rainbow trout (Oncorhynchus mykiss) has been studied. Fish were randomly separated in different lots according to their Zn-starvation and diet intake. In crude extracts of liver, gut and muscle, total and isoenzymatic superoxide dismutase and catalase activities were analysed. Lipid peroxidation was also determined in the same tissues. Western blotting was performed using antibodies against manganese- and copperzinc-containing superoxide dismutase. Lots fed on the Zn-deficient diet and with low intake showed significantly lower weight gain and feed-conversion efficiency indexes than control trouts. However, these parameters returned to control values when trouts were recovered by feeding them a control diet ad libitum. In control trouts, three independent copperzinc superoxide dismutase isozymes were detected in liver, whereas only one isozyme was present in the other lots. However, by Western blotting analysis the presence of a manganese superoxide dismutase was found in liver from all lots except in control trouts. Catalase activity and lipid peroxidation values were mainly detected in liver and gut, respectively, and both parameters increased in all lots with respect to the control group. Our results thus suggest that in rainbow trout an oxidative stress appears to occur as a consequence of Zn-deficiency.
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PMID:Oxidative stress generated by dietary Zn-deficiency: studies in rainbow trout (Oncorhynchus mykiss). 1180 21


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