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)

Preparations of rat lung microsomes containing 0.030-0.050 nmole of cytochromes P-450 and b5 per mg microsomal protein have been observed to contain significant levels of fatty acid desaturase activity. Both stearoyl CoA and palmitoyl CoA are desaturated to their monounsaturated analogues, oleic acid and palmitoleic acid, respectively. Activity (per mg microsomal protein) of the lung preparations varied according to the diet of the animals prior to killing in the order: fat free diet greater than normal rat chow greater than starvation. All preparations exhibited approximately 50% inhibition when incubated in the presence of 0.10 mM CN-. Maximal activity was obtained with the 0.50 mM NADH less activity with equal amounts of NADPH, and there was no synergistic interaction of NADH and NADPH together. The rate of desaturation was linear with protein concentrations between 0.15-1.5 mg microsomal protein/incubation at incubation times up to 8 min. A pH optimum range of 7.0-7.4 was observed. For all variables of fatty acid desaturase activity which were examined, the rate of desaturation of stearoyl CoA was approximately twice that for palmitoyl CoA. These results indicate that the same fatty acid desaturation system which is functional in the liver is also present in significant amounts in mammalian lungs.
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PMID:Characterization of fatty acid desaturase activity in rat lung microsomes. 0 14

Sulphate uptake by Anacystis nidulans under aerobic conditions in the light was found to be sensitive to metabolic poisons, such as N,N'-dicyclohexylcarbodiimide and carbonyl cyanide m-chlorophenyl hydrazone. It was also depressed by darkness. The sulphate absorption is an energy-dependent process. Sulphate uptake was also inhibited by chromate and selenate. Osmotic shock strongly affected sulphate uptake. This effect could be interpreted by a loss of a binding protein involved in the absorption of sulphate. Osmotic shock also depressed oxygen production in light and oxygen consumption in darkness; however, shocked cells were able to grow normally. Sulphate uptake was strongly enhanced by sulphate starvation, but this enhancement was partly prevented by chloramphenicol. Apparently sulphate starvation depressed the synthesis of a carrier involved in the transport of sulphate. During sulphate starvation the membrane potential, measured by the uptake of triphenylmethylphosphonium, increases. This may be due to changes in the membrane.
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PMID:Dependence of sulphate uptake by Anacystis nidulans on energy, on osmotic shock and on sulphate stravation. 2 Aug 62

The pool of coenzyme A--glutathione mixed disulfide (CoASSG) rapidly increased 2.0 times in response to oxygen starvation and 1.5 times in response to glucose starvation but did not change following ammonia starvation. The increase in the CoASSG pool resulted from an increase in the CoASSG fraction of the CoA pool from 42 to 66--93%. Fluoride, cyanide, chloramphenicol, and rifampicin all caused similar increases. Aerobic growth on fermentable sugars resulted in CoASSG making up 40--55% of the CoA pool while growth on nonfermentable carbon sources or anaerobic fermentation resulted in CoASSG replacing acetyl CoA and free CoA to make up 85--95% of the CoA pool. The CoASSG:ATP ratio varied inversely with the growth rate in two groupings of carbon sources made up of either fermentable or nonfermentable molecules. Cultures grown aerobically on fermentable sugars exhibited a lower CoASSG:ATP ratio reflecting the lower proportion of CoASSG in the CoA pool.
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PMID:Levels of coenzyme A--glutathione mixed disulfide in Escherichia coli. 35 37

1. There was no apparent correlation between the rate of respiration and rate of accumulation of proline in Candida albicans cells. 2. In contrast to normal cells, the respiration in the starved cells became completely cyanide insensitive. The starvation of cells in the presence of cycloheximide prevented the cells from becoming cyanide insensitive. The addition of Fe(III), however, accelerated the process. 3. Oxidizable substrates e.g. NADH, acetate and glucose, when added to cyanide-insensitive starved cells, exhibited 40--280% stimulation in respiration rate. However, this enhancement in oxidation by various substrates was not coupled to a simultaneous increase in the proline uptake or in intracellular ATP levels. 4. There was 6-fold stimulation in proline uptake when cyanide-insensitive cells were preincubated with 50 mM glucose. The preincubation of starved cells resulted in a partial restoration of cyanide sensitivity and increased intracellular ATP levels. The preincubation of starved cells with other oxidizable substrates resulted in a partial restoration of cyanide sensitivity but had no stimulatory effect on intracellular ATP levels and proline accumulation. 5. Both the enhanced uptake and ATP levels in glucose preincubated cells were found to be completely abolished by iodoacetate. 6. It is proposed that the increased proline uptake in cells preincubated with glucose was mainly due to the production of glycolytic energy.
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PMID:Characteristics of proline transport in normal and starved cells of Candida albicans. 36 34

Mitochondrial and peroxisomal fatty acid oxidation were compared in whole liver homogenates. Oxidation of 0.2 mM palmitoyl-CoA or oleate by mitochondria increased rapidly with increasing molar substrate:albumin ratios and became saturated at ratios below 3, while peroxisomal oxidation increased more slowly and continued to rise to reach maximal activity in the absence of albumin. Under the latter condition mitochondrial oxidation was severely depressed. In homogenates from normal liver peroxisomal oxidation was lower than mitochondrial oxidation at all ratios tested except when albumin was absent. In contrast with mitochondrial oxidation, peroxisomal oxidation did not produce ketones, was cyanide-insensitive, was not dependent on carnitine, and was not inhibited by (+)-octanoylcarnitine, malonyl-CoA and 4-pentenoate. Mitochondrial oxidation was inhibited by CoASH concentrations that were optimal for peroxisomal oxidation. In the presence of albumin, peroxisomal oxidation was stimulated by Triton X-100 but unaffected by freeze-thawing; both treatments suppressed mitochondrial oxidation. Clofibrate treatment increased mitochondrial and peroxisomal oxidation 2- and 6- to 8-fold, respectively. Peroxisomal oxidation remained unchanged in starvation and diabetes. Fatty acid oxidation was severely depressed by cyanide and (+)-octanoylcarnitine in hepatocytes from normal rats. Hepatocytes from clofibrate-treated rats, which displayed a 3- to 4-fold increase in fatty acid oxidation, were less inhibited by (+)-octanoylcarnitine. Hydrogen peroxide production was severalfold higher in hepatocytes from treated animals oxidizing fatty acids than in control hepatocytes. Assuming that all H2O2 produced during fatty acid oxidation was due to peroxisomal oxidation, it was calculated that the contribution of the peroxisomes to fatty acid oxidation was less than 10% both in cells from control and clofibrate-treated animals.
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PMID:Mitochondrial and peroxisomal fatty acid oxidation in liver homogenates and isolated hepatocytes from control and clofibrate-treated rats. 43 7

The effect of clofibrate treatment on hepatic ketogenic capacity was studied in rats. Ketogenesis from octanoate and oleate was increased 2- and 4,5-fold, respectively, in hepatocytes from fed, treated rats. In contrast to controls ketogenic rates did not increase upon starvation. While ketogenesis from oleate was higher in fed, treated animals than in fasted controls, endogenous ketogenesis was lower and increased upon starvation. Ketogenesis from octanoate and oleate was stimulated approx. 2-fold in homogenates from treated animals. Labeled pyruvate and succinate oxidation was unaltered. [1-14C]Oleate oxidation was severely inhibited by cyanide, both in homogenates from controls and treated animals. Clofibrate caused a 3-fold increase in hepatic carnitine levels. Catalase and glutamate dehydrogenase activities were also increased by the drug. Cytochrome c oxidase did not change. Despite their increased ketogenic capacity hepatocytes from treated rats esterified as much oleate as controls. The increased oxidation was matched by an increased oleate uptake. Plasma ketones were increased 2-fold in fasted, treated animals. Plasma free fatty acids were unaffected. It is concluded that the enhanced ketogenic capacity induced by clofibrate is the result of an increase in mitochondrial beta-oxidation, an increase in the activity of carnitine palmitoyltransferase and possibly of the observed increases in hepatic carnitine content and fatty acid uptake.
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PMID:Hepatic fatty acid oxidation and ketogenesis after clofibrate treatment. 65 51

Microplasmodia of Physarum polycephalum used in this study form spherules after 18 h of starvation. Stereological morphometry revealed that between the 2nd and the 5th hour of starvation the number of mitochondria in 1 mm3 of cytoplasm rises from about 12 to 24 millions and the mean volume of mitochondria drops from circa 4.6 to 3.0 microns3. This denotes the synchronous division of mitochondria. The daughter mitochondria show an increase in density of the matrix and a decrease in condensation of the net of tubular cristae. The mitochondrial division, decrease in activity of the respiratory chain and maximum of its cyanide resistance occur at the same time.
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PMID:Division of Physarum mitochondria during starvation. 203 91

Bacterial cells degrade intracellular proteins at elevated rates during starvation and can selectively degrade proteins by energy-dependent processes. Sporulating bacteria can degrade protein with apparent first-order rate constants of over 0.20 h-1. We have shown, with an optimized [14C]leucine-labeling and chasing procedure, in a chemically defined sporulation medium, that intracellular protein degradation in sporulating cells of Bacillus subtilis 168 (trpC2) is apparently energy dependent. Sodium arsenate, sodium azide, carbonyl cyanide m-chlorophenylhydrozone, and N,N'-dicyclohexylcarbodiimide, at levels which did not induce appreciable lysis (less than or equal to 10%) over 10-h periods of sporulation, inhibited intracellular proteolysis by 13 to 93%. Exponentially growing cells acquired arsenate resistance. In contrast to earlier reports, we found that chloramphenicol (100 micrograms/ml) strongly inhibited proteolysis (68%) even when added 6 h into the sporulation process. Restricting the calcium ion concentration (less than 2 microM) in the medium had no effect on rates or extent of vegetative growth, strongly inhibited sporulation (98%), and inhibited rates of proteolysis by 60% or more. Inhibitors of energy metabolism, at the same levels which inhibited proteolysis, did not affect the rate or degree of uptake of Ca2+ by cells, which suggested that the Ca2+ and metabolic energy requirements of proteolysis were independent. Restricting the Ca2+ concentration in the medium reduced by threefold the specific activity in cells of the major intracellular serine proteinase after 12 h of sporulation. Finally, cells of a mutant of B. subtilis bearing an insertionally inactivated gene for the Ca2(+)-dependent intracellular proteinase-1 degraded protein in chemically defined sporulation medium at a rate indistinguishable from that of the wild-type cells for periods of 8 h.
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PMID:Energy and calcium ion dependence of proteolysis during sporulation of Bacillus subtilis cells. 211 63

Periplasmic permeases are composed of four proteins, one of which has an ATP-binding site that has been postulated to be involved in energy coupling. Previous data suggested that these permeases derive energy from substrate level phosphorylation (Berger, E. A. (1973) Proc. Natl. Acad. Sci. U.S.A. 70, 1514-1518); however, conflicting results later cast doubt upon this hypothesis. Here, we make use of two well characterized periplasmic permeases and of a well characterized unc mutant (ATPase-) to examine this energetics problem in depth. We have utilized the histidine and maltose periplasmic permeases in Escherichia coli as model systems. Isogenic unc strains were used in order to study separately the effect of the proton-motive force and of ATP on transport. These parameters were analyzed concomitantly with transport assays. Starvation experiments indicate that both histidine and maltose transport require ATP generation and that a normal level of delta psi is not sufficient. Uncouplers such as carbonyl cyanide-m-chlorophenylhydrazone and 2,4-dinitrophenol dissipated the delta psi without decreasing the ATP level and without significant effect on these permeases, showing that delta psi is not needed. Inhibition of ATP synthesis by arsenate eliminates transport through both permeases, confirming the need for ATP. In agreement with previous results with the glutamine permease (Plate, C. A. (1979) J. Bacteriol. 137, 221-225), valinomycin plus K+ dissipates delta psi without affecting ATP levels and inhibits histidine transport; however, maltose transport is not inhibited under these conditions. This result is discussed in terms of the artefactual side effects caused by valinomycin/K+ treatment on some periplasmic permeases. Histidine transport is also shown to be sensitive to changes in the cytoplasmic pH. It is concluded that periplasmic permeases indeed have an obligatory requirement for ATP (or a closely related molecule), whereas the proton-motive force is neither sufficient nor essential.
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PMID:Energy coupling in bacterial periplasmic transport systems. Studies in intact Escherichia coli cells. 264 55

Transcription of the cobinamide biosynthetic genes (the CobI operon) was induced under three different physiological conditions: anaerobiosis (anaerobic respiration or fermentation), aerobic respiration at low oxygen levels, and aerobic respiration with a partial block of the electron transport chain. After a shift to inducing conditions, there was a time lag of approximately 50 min before the onset of CobI induction. Under conditions of anaerobic respiration, the level of CobI transcription was dependent on the nature of both the electron donor (carbon and energy source) and the acceptor. Cells grown with electron acceptors with a lower midpoint potential showed higher CobI expression levels. The highest level of CobI transcription observed was obtained with glycerol as the carbon source and fumarate as the electron acceptor. The high induction seen with glycerol was reduced by mutational blocks in the glycerol catabolic pathway, suggesting that glycerol does not serve as a gratuitous inducer but must be metabolized to stimulate CobI transcription. In the presence of oxygen, CobI operon expression was induced 6- to 20-fold by the following: inhibition of cytochrome o oxidase with cyanide, mutational blockage of ubiquinone biosynthesis, and starvation of mutant cells for heme. We suggest that the CobI operon is induced in response to a reducing environment within the cell and not by the absence of oxygen per se.
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PMID:Redox regulation of the genes for cobinamide biosynthesis in Salmonella typhimurium. 268 49


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