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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tellurite (TeO3(2-)) is highly toxic toward Escherichia coli (MIC, approximately 1 microgram ml-1). Mutants (Tel) that were resistant to low levels of TeO3(2-) (MIC, approximately 10 micrograms ml-1) and collaterally resistant to arsenate were isolated. These Tel mutants were unable to grow on media containing low levels of Pi, which supported growth of the parent strain. When grown at much higher Pi levels they exhibited depressed levels of the outer membrane phoE protein and the periplasmic phoS protein, as well as several other proteins indicative of Pi starvation. Tel mutants were markedly defective in 32Pi transport, and TeO3(2-) was shown to be a potent competitive inhibitor of 32Pi transport in the parent strain. The Tel phenotype could be complemented by an F' plasmid harboring the phoR, phoB, and phoA loci, and curing of the F' plasmid completely restored TeO3(2-) resistance. Of a variety of well-characterized Pi transport mutants, only phoB mutants were equally resistant to TeO3(2-), and susceptibility could also be restored in strains carrying an F' plasmid for the phoB region and lost once more after F' curing. The tel and phoB loci were equally cotransducible with lac. Tel mutants still synthesized alkaline phosphatase, the phoA gene product, after Pi starvation, suggesting that the phoB locus per se was not involved because phoB is a positive regulatory gene for phoA expression. The results indicate that TeO3(2-) is transported into E. coli by a phosphate transport system and that resistance to TeO3(2-) specifically selects for as yet uncharacterized mutants in the phoB-phoA region of the chromosome.
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PMID:Tellurite susceptibility and non-plasmid-mediated resistance in Escherichia coli. 294 76

We show that N. crassa represses the production of acid phosphatase at pH higher than 8.0, irrespective of the carbon source used, whereas production was stimulated by sucrose at slightly acidic pH. The same profile of acid phosphatase production was observed in the pho-2A, pho-3A, nuc-1A, nuc-2A and pregc mutant strains. We also show that acid phosphatase synthesized by the pregc mutant strain grown on high phosphate medium has pronounced differences when compared to the enzyme synthesized by the wild-type strain grown on low phosphate medium in terms of heat stability, steady-state kinetic properties and DEAE-cellulose chromatography. In addition, the synthesis and/or secretion of only phosphate-repressible alkaline phosphatase is affected by mutations in acu-1, and acu-5 and acu-7 genes. These results, which indicate distinct pathways for the synthesis and secretion of acid and alkaline phosphatases in N. crassa, contradict the dosage titration model proposed by Metzenberg et al. (1974) whereby the synthesis of these enzymes should occur through a single hierarchical regulatory circuit as a response to phosphate starvation.
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PMID:Regulation of synthesis and secretion of acid and alkaline phosphatases in Neurospora crassa. 296 23

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.
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PMID:Changes in Escherichia coli cells starved in seawater or grown in seawater-wastewater mixtures. 311 27

The effect of heat shock on Myxococcus xanthus was investigated during both glycerol- and starvation-induced development. Cells heat shocked at 40 degrees C for 1 h prior to a development-inducing signal displayed an accelerated rate of myxospore formation at 30 degrees C. Additionally, M. xanthus cells heat shocked prior to glycerol induction formed a greater total number of myxospores when sporulation was complete than did control cells maintained at 30 degrees C. However, in starvation-induced fruiting cells the total number of myxospores in control and heat-shocked populations was about equal when fruiting body and myxospore formation was complete. When extended heat shock (3 h) was applied to cells prior to development, no acceleration of myxospore formation was observed. Heat shock elicited the premature expression of many developmentally regulated proteins. Cell fractionation and analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography revealed the subcellular location and molecular weights of the 18 glycerol-induced and 9 starvation-induced developmental proteins. Comparison with previously identified M. xanthus heat shock proteins showed that nine of the developmental proteins found in glycerol-induced cells and three of the developmental proteins found in starvation-induced cells were heat shock proteins. Furthermore, heat shock increased the activity of alkaline phosphatase, a developmentally regulated enzyme, in vegetative cells, glycerol-induced cells, and starvation-induced cells.
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PMID:Acceleration of starvation- and glycerol-induced myxospore formation by prior heat shock in Myxococcus xanthus. 314 80

The intracellular nucleotide pool of Escherichia coli W3110 reproducibly changes from conditions of growth in phosphate excess to phosphate starvation, with at least two nucleotides appearing under starvation conditions and two nucleotides appearing only under excess phosphate conditions. Strains bearing a deletion of the phoA gene show the same pattern, indicating that dephosphorylation by alkaline phosphatase is not responsible for the changes. Strains with mutations in the phoU gene, which result in constitutive expression of the pho regulon, show the nucleotide pattern of phosphate-starved cells even during phosphate excess growth. These changes in nucleotides are therefore due to phoU mutation but not to alkaline phosphatase constitutivity. In fact, a phoR (phoR68) mutant strain has the patterns of the wild type in spite of being constitutive for alkaline phosphatase. That these nucleotides might be specific signals for pho regulon expression was supported by the fact that the two nucleotides appearing under phosphate starvation induced the synthesis of alkaline phosphatase in repressed permeabilized wild-type cells under conditions of phosphate excess.
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PMID:Nucleotide pool in pho regulon mutants and alkaline phosphatase synthesis in Escherichia coli. 351 76

New pleiotropic mutants were isolated that express either the phoA, psiE or psiO promoter constitutively and simultaneously alter bacterial alkaline phosphatase regulation, carbon utilization or ultraviolet light sensitivity. To do this, Lac+ mutants were isolated from strains with the appropriate lacZ transcriptional fusions. Over 300 independent mutants were characterized, and all that constitutively express phoA map in phoR, phoU, the phosphate-specific transport system or a new locus called phoF. However, only phoU mutants express both phoA and psiE constitutively. Carbohydrate-utilizing mutants that show constitutive expression of psiE and psiO map in cya, crp and, possibly, crr. Also, numerous ultraviolet-light-sensitive mutants were discovered that show increased psiO expression and map in lon. Some other mutations that lead to constitutive psiO expression (which is normally induced either by phosphate, nitrogen or carbon starvation or anoxia) show decreased expression of phoA. Also, several mutants were found that show an unusual metastable character affecting psiO or phoA transcription. In these, colonies spontaneously switch between an induced and repressed "state" with respect to lac or bacterial alkaline phosphatase expression. In some, the clonal variation of the lactose phenotype or bacterial alkaline phosphatase synthesis is recA-independent and phenotypically resembles phase variation in Salmonella typhimurium. The latter class are called "phase mutants". The mutants are discussed in terms of protein-nucleic acid interactions and/or possible changes in the DNA, i.e. modifications or rearrangements, within the phosphate gene system, that are physiologically regulated.
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PMID:Novel regulatory mutants of the phosphate regulon in Escherichia coli K-12. 354 Mar 12

Synthesis of alkaline phosphatase in Escherichia coli is derepressed under phosphate starvation in the stringent strain CP78 as well as in its relaxed counterpart CP79. During limitation of phosphate as well as of amino acids a decrease of enzyme activity is observed, especially in the relaxed strain, which can not produce ppGpp under this conditions. After phosphate limitation synthesis of ppGpp is not stimulated and the kinetics of RNA synthesis is similar in both strains. We suggest that ppGpp is not directly involved in the regulation of gene expression during phosphate starvation.
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PMID:[Synthesis of alkaline phosphatase in a stringent and a relaxed strain of Escherichia coli under amino acid and phosphate limitation]. 389 9

A kinetic study of Pi transport with 32Pi revealed that Saccharomyces cerevisiae has two systems of Pi transport, one with a low Km value (8.2 microM) for external Pi and the other with a high Km value (770 microM). The low-Km system was derepressed by Pi starvation, and the activity was expressed under the control of a genetic system which regulates the repressible acid and alkaline phosphatases. The function of the PHO2 gene, which is essential for the derepression of repressible acid phosphatase but not for the derepression of repressible alkaline phosphatase, was also indispensable for the derepression of the low-Km system.
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PMID:Regulation of inorganic phosphate transport systems in Saccharomyces cerevisiae. 390 5

Hiraga, Sota (Osaka University, Osaka, Japan). Regulation of synthesis of alkaline phosphatase by deoxyribonucleic acid synthesis in a constitutive mutant of Bacillus subtilis. J. Bacteriol. 91:2192-2199. 1966.-It was found that synthesis of alkaline phosphatase (APase) correlated with deoxyribonucleic acid (DNA) synthesis in a partially constitutive mutant of Bacillus subtilis. When cultures of the mutant were made to undergo synchronous growth by germination of spores in an excess-phosphate medium, synthesis of APase was repressed at the beginning of DNA synthesis. If the initiation of DNA synthesis was inhibited by thymine starvation, the repression of APase was not observed. When DNA synthesis, previously initiated, was inhibited by thymine or uracil starvation, or by addition of mitomycin C, the repression was partially released at a later stage. In contrast, this correlation between repression and DNA synthesis was not observed in a repressible strain.
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PMID:Regulation of synthesis of alkaline phosphatase by deoxyribonucleic acid synthesis in a constitutive mutant of Bacillus subtilis. 495 12

1. The purification of the ;vegetative' alkaline phosphatase of Bacillus subtilis 168 was simplified by ionic elution of the enzyme from intact cells. 2. The enzyme has a molecular weight of about 70000 and treatment of the enzyme with 10mm-hydrochloric acid or 6.0m-guanidine hydrochloride, beta-mercaptoethanol (0.1m) gives rise to enzymically inactive subunits. 3. The amino acid composition of the enzyme was determined. The N-terminal residue determined by the DNS chloride method is glycine. 4. The properties of this enzyme were compared with the ;sporulation' alkaline phosphatase of the same strain. 5. Although the ;sporulation' enzyme differs from the ;vegetative' enzyme in its physiology of appearance and apparent mRNA stability, an examination of properties of the enzymes revealed no differences. 6. The enzyme from both cell forms is bound to the particulate fraction of cell extracts, but can be solubilized by high concentrations of magnesium chloride; removal of the magnesium chloride, by dialysis, results in precipitation of both enzymes. Both enzymes can be removed from intact cells by ionic elution. 7. The ;vegetative' and ;sporulation' enzymes have identical pH optima, K(m) and K(i) values and electrophoretic mobilities in cellulose acetate. 8. Their half-life is 28min at 65 degrees C and their Q(10) is 1.25. 9. The molecular size determined by gel filtration on Sephadex G-100 is about 69000. 10. ;Vegetative' and ;sporulation' forms gave precipitin lines that were continuous and non-spurred when tested against antiserum prepared against the ;vegetative' enzyme. 11. The ;sporulation' alkaline phosphatase appears to be associated with stage II of sporulation and appears to be induced by something specifically concerned in sporulation and not by phosphate starvation.
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PMID:Sporulation in Bacillus subtilis 168. Comparison of alkaline phosphatase from sporulating and vegetative cells. 500 77


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