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

Seven strains of Campylobacter jejuni, isolated from various sources [human (n = 2), chicken (n = 3), water (n = 2)], were studied under starvation conditions in filter-sterilized and pasteurized surface water by acridine orange direct count (AODC), viable count (DVC) and culture methods. Plate counts showed a rapid decline (2 log-units/day) for all strains under these conditions. Only one of the seven strains (14%) showed a (prolonged) viable, non-culturable 'state'. The ability of these viable, non-culturable cells to colonize the intestine was tested on day-old chicks. The infectious oral dose of freshly cultured cells of this model was 26-260 cfu; 1.8 x 10(5) viable, non-culturable C. jejuni were introduced to day-old chicks orally. Campylobacter jejuni was not isolated from the caeca of the chicks after incubation for 7 d. Also, passage through the allantoic fluid of embryonated eggs did not recover viable, non-culturable C. jejuni. These findings cast serious doubts on the significance of the viable, non-culturable 'state' in environmental transmission of C. jejuni.
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PMID:Lack of colonization of 1 day old chicks by viable, non-culturable Campylobacter jejuni. 164 8

beta-Lipotropin, a pituitary peptide, is a strong stimulator of lipolysis in rabbit adipose tissue. This polypeptide is shown to be degraded by intact fat pads, homogenized adipose tissue and adipocytes of the rabbit dependent on the amount of adipose tissue, time and the pH of the incubation medium. In subcellular fractions of rabbit adipocytes the proteolytic activity could be localized into the cytosol and the microsomal fraction. To obtain information about the processing of beta-lipotropin in its target cell lipolysis and degradation of this polypeptide were investigated in the presence of inhibitors of distinct cellular mechanisms and in different physiological states such as obesity and starvation. Thus, the stronger lipolytic response in adipocytes from obese rabbits respectively animals fed ad libitum was accompanied by a significantly increased degradation in comparison to lean respectively starved rabbits. The six lysosomotropic agents (chloroquine, NH4Cl, propranolol, quinacrine, acridine orange and tetracaine), the proteinase inhibitors alpha 2-macroglobulin and monodansylcadaverine, cellular ATP depletion by 2-deoxy-D-glucose and 2,4-dinitrophenol and the omission of Ca2+ ions from the incubation medium inhibited dose-dependently the lipolytic activity as well as the degradation of beta-lipotropin in intact and homogenized adipose tissue. Inhibitors of the cytoskeleton such as colchicine, cytochalasin B, vinblastine and concanavalin A also reduced lipolysis but only the degradation in intact adipose tissue. It can be concluded that after receptor-mediated uptake the cytoskeleton and lysosomal proteases are involved in the processing of beta-lipotropin.
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PMID:Processing of the lipid-mobilizing peptide beta-lipotropin in rabbit adipose tissue. 221 32

This paper reports the isolation and characterization of Chinese hamster ovary cell mutants defective in low density lipoprotein (LDL)-cholesterol trafficking. The parental cell line was 25-RA, which possesses LDL receptors and various cholesterogenic enzyme activities that are partially resistant to down regulation by exogenous sterols (Chang, T. Y., and J. S. Limanek. 1980. J. Biol. Chem. 255:7787-7795). Because these cells accumulate a large amount of intracellular cholesteryl ester when grown in medium containing 10% fetal calf serum, mutagenized populations of 25-RA cells were grown in the presence of a specific inhibitor of acyl-coenzyme A: cholesterol acyltransferase (ACAT), which depleted their cholesteryl ester stores. Without this cholesterol ester storage, 99% of 25-RA cells die after 5-d growth in cholesterol starvation medium, while the mutant cells, which accumulate free cholesterol intracellularly, survived. In two mutant clones chosen for characterization, activation of cholesteryl ester synthesis by LDL was markedly reduced in the mutant cells compared with 25-RA cells. This lack of activation of cholesterol ester synthesis in the mutant cells could not be explained by defective uptake and/or processing of LDL or by a decreased amount of ACAT, as determined by in vitro enzyme activity. Mutant cells grown in the presence of LDL contain numerous cytosolic particles that stain intensely with the fluorescent compound acridine orange, suggesting that they are acidic. The particles are also stained with filipin, a cholesterol-specific fluorescent dye. Indirect immunofluorescence with a monoclonal antibody specific for a lysosomal/endosomal fraction revealed a staining pattern that colocalized with the filipin signal. The mutant phenotype was recessive. The available evidence indicates that the mutant cells can take up and process LDL normally, but the hydrolyzed cholesterol accumulates in an acidic compartment, probably the lysosomes, where it can not be transported to its normal intracellular destinations.
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PMID:Isolation and characterization of Chinese hamster ovary cell mutants defective in intracellular low density lipoprotein-cholesterol trafficking. 240 88

A single-gene nuclear mutant has been selected from the yeast Schizosaccharomyces pombe for growth resistance to Dio-9, a plasma membrane H+-ATPase inhibitor. From this mutant, called pma1, an ATPase activity has been purified. It contains a Mr = 100,000 major polypeptide which is phosphorylated by [gamma-32P] ATP. Proton pumping is not impaired since the isolated mutant ATPase is able, in reconstituted proteoliposomes, to quench the fluorescence of the delta pH probe 9-amino-6-chloro-2-methoxy acridine. The isolated mutant ATPase is sensitive to Dio-9 as well as to seven other plasma membrane H+-ATPase inhibitors. The mutant H+-ATPase activity tested in vitro is, however, insensitive to vanadate. Its Km for MgATP is modified and its ATPase specific activity is decreased. The pma1 mutation decreases the rate of extracellular acidification induced by glucose when cells are incubated at pH 4.5 under nongrowing conditions. During growth, the intracellular mutant pH is more acid than the wild type one. The derepression by ammonia starvation of methionine transport is decreased in the mutant. The growth rate of pma1 mutants is reduced in minimal medium compared to rich medium, especially when combined to an auxotrophic mutation. It is concluded that the H+-ATPase activity from yeast plasma membranes controls the intracellular pH as well as the derepression of amino acid, purine, and pyrimidine uptakes. The pma1 mutation modifies several transport properties of the cells including those responsible for the uptake of Dio-9 and other inhibitors (Ulaszewski, S., Coddington, A., and Goffeau, A. (1986) Curr. Genet. 10, 359-364).
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PMID:A single mutation confers vanadate resistance to the plasma membrane H+-ATPase from the yeast Schizosaccharomyces pombe. 287 25

The uptake of the fluorescent, lysosomotropic weak base acridine orange (AO) by living cells in culture was studied by flow cytofluorometry. A mouse myeloma cell line (SP 2/0), growing in suspension, and an anchorage-dependent human malignant glioma cell line (U-251 MG), brought into suspension by trypsinization, were used. The consequences of trypsinization were also studied using static cytofluorometry. The lysosomal accumulation of AO by myeloma cells growing in suspension was found to be only moderately affected by starvation (i.e. incubation without medium change) for a period of up to five days. Trypsinization of the glioma cells after staining with AO caused pronounced release of the fluorescent dye while trypsinization before staining with AO did not significantly change the average lysosomal concentration of AO. We did, however, notice certain side effects of trypsinization in the form of both increased cellular green fluorescence and greater intercellular variability that reduce the validity of data obtained from cells detached by routine trypsinization. In conclusion, the condition of the lysosomal vacuome of living cultured cells growing in suspension may be studied by flow cytofluorometry after vital staining with the lysosomotropic weak base AO. Anchorage-dependent trypsinized cells, however, yield unsatisfactory results when examined in a flow cytofluorometer system and are better studied while still attached to their substratum, using static cytofluorometry.
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PMID:Flow cytofluorometry of lysosomal acridine orange uptake by living cultured cells. Effect of trypsinization and starvation. 361 27

The round nucleoli of chick embryo myoblasts, when grown in a culture medium devoid of arginine, unravel in several days into 5-20 micro long, beaded strands termed nucleolar necklaces (NN). Addition of arginine reverses this change. The NN contain protein, RNA, and traces of DNA as determined cytochemically by enzyme digestion and by acridine-orange fluorescent staining. When a cell containing the beaded strand is treated with agents, such as actinomycin D, that prevent rRNA polymerase action, the strand collapses and condenses into a small dense nucleolus with segregated regions of ribonucleoprotein (RNP) and deoxyribonucleoprotein (DNP). The properties of the NN appear to resemble those of the nucleolar necklaces of amphibian oocytes. Cycloheximide or puromycin inhibition of general protein synthesis does not lead to NN formation. We suggest that NN formation during arginine starvation may be a result of a singular depletion of some rapidly turning over, arginine-rich proteins that normally attach to ribosomal RNA precursor molecules during their synthesis in the processing towards maturation of the ribosomes.
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PMID:Nucleolar necklaces in chick embryo myoblasts formed by lack of arginine. 410 77

Guanine auxotrophs of Escherichia coli K-12 were isolated after mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine, ethyl methane sulfonate, or the acridine mustard ICR 372. guaA (xanthosine 5'-monophosphate [XMP] aminase-less) mutants were distinguished from guaB (inosine 5'-monophosphate [IMP] dehydrogenase-less) mutants by their growth response to xanthine and by enzyme assay. Mutations were classified as base substitutions or frameshift on the basis of mutagen-induced reversion patterns. All guaA strains, including three frameshift mutants, produced derepressed levels of IMP dehydrogenase when cultured with a growth-limiting concentration of guanine. The guaB strains were of two types: (i) those producing derepressed levels of XMP aminase, and (ii) those producing basal levels of XMP aminase when grown under conditions of guanine starvation. In the guaB strains of the second type, the expression of the adjacent guaA gene is reduced. It is proposed that this pleiotropic effect of some guaB mutations is a result of polarity. The orientation of polarity suggests the gene order "operator"-guaB-guaA. Gel diffusion studies with IMP dehydrogenase antiserum showed that strains carrying polar guaB mutations do not produce cross-reacting material (CRM). The remaining guaB mutants were either CRM(+) or CRM(-). Mapping the mutations by three-factor crosses showed that polar and nonpolar guaB sites are clustered in a small genetic region cotransducible with guaA. The relative positions of the guaB mutational sites established that the polar mutations lie within the structural gene for IMP dehydrogenase.
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PMID:The gua operon of Escherichia coli K-12: evidence for polarity from guaB to guaA. 435 75

The ability of flow cytometry to detect and enumerate viable bacteria during survival in a lakewater microcosm was assessed using Staphylococcus aureus as a model organism. Counts of colony-forming units (c.f.u.) on nutrient agar were not significantly different from those obtained by flow cytometric detection of rhodamine 123 stained bacteria and there was no evidence for a viable but nonculturable state using these methods. However c.f.u. were significantly lower when estimated using mannitol salts agar compared with nutrient agar. S. aureus was also enumerated immunofluorescently after staining with FITC-IgG. There was no significant difference between the population estimated immunofluorescently and by acridine orange direct counting, and unlike estimations of viability, only slight reductions in total cell numbers were observed. Changes in the protein and nucleic acid content of S. aureus during survival were also measured by flow cytometry to investigate any potential heterogeneity arising within the starved population. Flow cytometric determinations were found to correlate significantly with their respective chemical determinations. These results demonstrate the ability of flow cytometry to detect viable bacteria during starvation and to study changes in macromolecular content. They also illustrate the importance of using appropriate methods for the detection of viable bacteria in environmental samples.
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PMID:Survival of Staphylococcus aureus in lakewater monitored by flow cytometry. 751 71

Sequence analysis of domains 3 and 4 of 23S rRNA from Pseudomonas fluorescens Ag1 was carried out to allow the design of a strain-specific rRNA oligonucleotide probe targeting this strain. The specificity of the probe, Ps-Ag1, was assessed by dot blot analysis and whole-cell hybridization, and it was found to be specific for P. fluorescens Ag1. The correlation between the ribosomal content of P. fluorescens Ag1 and growth rate was determined during balanced growth conditions with generation times ranging from 1.2 to 31.8 h. Hybridization of the rRNA-targeting probes combined with charged coupled device-enhanced microscopy was used to determine the rRNA content. The total RNA content per cell was determined by staining with acridine orange and charged coupled device-enhanced microscopy. After 2 h under carbon starvation conditions, the rRNA content per cell decreased to 45% of the content of an exponentially growing cell. After 1 day of carbon starvation, the rRNA content had decreased to 20%. When cells were grown at different temperatures, it was found that the rRNA content per cell was only dependent on the substrate in the temperature range from 5 to 30 degrees C. P. fluorescens Ag1 was used in a mesocosm release experiment. The strain could be detected by use of the oligonucleotide probe targeting rRNA for 8 days in the water column and for 10 days on solid surfaces. The standard curve correlating growth rate with rRNA content was used to estimate the physiological activity of P. fluorescens Ag1 in the mesocosm experiment.
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PMID:Application of a strain-specific rRNA oligonucleotide probe targeting Pseudomonas fluorescens Ag1 in a mesocosm study of bacterial release into the environment. 753 76

A naturally luminescent bacterium, Vibrio harveyi, and two bacteria, Escherichia coli and Pseudomonas fluorescens, which had been genetically marked with luminescence were starved in liquid medium at 4 and 30 degrees C for 54 days. Total cell concentrations and concentrations of culturable and viable cells were determined by acridine orange staining, dilution plate counting, and direct viable counting, respectively, and population activity was measured by luminometry. V. harveyi became nonculturable but maintained viability during starvation at 4 degrees C and maintained both culturability and viability at 30 degrees C. In contrast, E. coli became viable but nonculturable during starvation at 30 degrees C but not at 4 degrees C. Luminescence of nonculturable cells of both strains, and culturable cells of V. harveyi, decreased to background levels during starvation. Luminescence of starved culturable cells of E. coli also fell below background levels but occasionally increased to detectable values. Viable, nonculturable forms of P. fluorescens were not detected at either temperature, and cells starved at 4 degrees C showed no decrease in luminescence measured during incubation of samples at 25 degrees C. Following incubation of late-log-phase cells with yeast extract and nalidixic acid, changes in light output directly paralleled changes in cell length, as observed during direct viable counting. Quantification of changes in luminescence following incubation of starved cells with yeast extract enabled measurement of the activity of both culturable and viable but nonculturable cells. Measurement of luminescence was significantly more sensitive, rapid, and convenient in quantifying activity following nutrient amendment than measurement of changes in cell length.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Luminescence-based detection of activity of starved and viable but nonculturable bacteria. 801 19


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