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)

Glycogen synthase I (UDP glucose: glycogen alpha-4-glycosyltransferase, EC2.4.1.11) of the tapeworm Hymenolepis diminuta is the form of the enzyme which is active in vivo, while the D-form represents an inactive "storage form." Utilizing the differential effect of inorganic phosphate (Pi) on the I and D-forms, the ratio of the 2 forms in vivo has been determined under conditions of starvation of the host and refeeding of the parasite with glucose. This procedure reveals that conversion of the inactive D-form to the active I-form takes place when glycogen-depleted worms are incubated in glucose. The activity of glycogen synthase I also is affected by the molecular weight of the primer glycogen. With certain molecular weight fractions, enzymatic activity is higher than with others. This specificity of the glycogen primer could explain the relatively low concentrations of those molecular weight fractions which confer the highest synthase activity.
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PMID:Glycogen synthase of Hymenolepis diminuta. II. Nutritional state, interconversion of forms, and primer glycogen molecular weight as control factors. 10 7

Control individuals contained no lead in the chloragocytes but high alpha-glycogen rosette reserves. Starvation of contaminated earthworms for 4d caused a lead loss and the chlorgocytes possessed fewer debris vesicles than those of unstarved worms, suggesting that the debris vesicles may be the route for at least some of the lead loss. No glycogen deposits were observed in the chloragocytes of starved or unstarved earthworms from contaminated soil. Maintenance of contaminated earthworms in potting compost caused lead losses similar to those sustained by starvation, but the chloragocyte cytoplasm possessed beta-glycogen reserves. Specimens maintained in lead-spiked potting compost showed lead levels similar to those of earthworms taken directly from contaminated soil. No beta-glycogen accumulations were observed under this enriched regime. Although the possible interference of lead in carbohydrate metabolism is discussed, the results do not wholly support metabolic inhibition by lead. It is hypothesised that lead sequestration is energy-demanding and that in the absence of an energy-rich diet glycogen stores fail to accumulate. In the presence of an organic-rich medium, elevated lead levels preclude glycogen formation, because of the high sequestration-demand, but at lower lead levels beta-glycogen deposits occur if a high organic diet is available.
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PMID:Glycogen-lead relationship in the earthworm Dendrobaena rubida from a heavy metal site. 65 70

Caenorhabditis elegans concentrates its food, bacteria, by pharyngeal pumping. The rate of pumping is affected by the presence of bacteria. Using a new assay that allows measurement of pumping rate in a population of worms suspended in liquid by measuring their uptake of microscopic iron particles, we have confirmed and quantitated this effect. Furthermore, we demonstrated that starvation stimulates pumping. Worms that had been deprived of bacteria for more than 4 hours pumped in the absence of bacteria under conditions in which well-fed worms did not. Furthermore, starved worms responded to lower amounts of bacteria than did fed worms. The assay was also useful for measuring effects of drugs on pumping. Of about 30 chemicals screened, 5 had clear effects. The neurotransmitter serotonin and the serotonin uptake inhibitor imipramine stimulated pumping, while the serotonin antagonist gramine inhibits. Imipramine stimulation is greatly decreased in cat-1 and cat-4 mutants, which have low levels of serotonin. Muscimol, an agonist for the neurotransmitter GABA, and ivermectin, whose site of action may also be the GABA receptor, both inhibit pumping. Qualitative observations suggested a role for acetylcholine in the regulation of pumping.
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PMID:Effects of starvation and neuroactive drugs on feeding in Caenorhabditis elegans. 218 Oct 52

Effect of praziquantel on inward and outward Ca++ fluxes was investigated in Hymenolepis diminuta in glucose supplemented balanced electrolyte solution and under conditions of glucose/Mg++ deficiency. The 45Ca++ uptake in freshly isolated worms presented, generally, a biphasic kinetics. This comprised of an initial fast uptake phase, followed by a continued slower influx. The initial fast kinetics showed insensitivity to or slight stimulation by praziquantel depending on its concentration, and such stimulatory action was particularly prominent under Mg++ deficient condition (P less than 0.01). The subsequent slower 45Ca++ uptake was, however, markedly inhibited by the drug under both these conditions (P less than 0.01). Glucose starvation of the worms resulted in abolition of the fast 45Ca++ influx phase and uniform inhibition by the praziquantel without any indication of initial stimulatory effect (P less than 0.01). The extrusion of 45Ca++ from the label preloaded worms was stimulated by praziquantel under all the conditions investigated (P less than 0.01).
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PMID:Action of praziquantel on calcium transport in Hymenolepis diminuta. 323 78

Female Schistosoma mansoni from unisexual infections have scant pharyngeal musculature, thin intestinal cecal walls, pale and scanty intestinal contents, and lack acidic thiol proteinase digestive enzyme as determined by indirect immunofluorescence using a monoclonal antibody. Their intake of host erythrocytes, measured by 51Cr labeling, is about one-fourth that of paired adult females, and they appear to be starved. In contrast, paired adult females have heavier pharyngeal musculature and intestinal cecal walls and abundant digestive enzyme in the anterior third of their intestinal tract. Females in worm pairs surgically transplanted into uninfected mice continued to feed, but separated females were carried into the liver and deteriorated. Adult female S. mansoni, newly separated from their male partners and incubated in vitro with labeled erythrocytes, ingested marginally fewer cells than did still-paired females, indicating their ability to continue feeding almost normally at least for a period after separation. Paired and ex-paired adult females declined similarly in feeding rate with increased time in vitro. In Schistosomatium douthitti, females grow and mature without males, the pharyngeal musculature and cecal walls are well developed, the gut is full of ingested blood, and the acidic thiol proteinase is present in both unisexual and paired female worms. There are different stimulatory pathways for growth and for reproductive maturation in S. mansoni, although both processes require physical contact with the male. We believe that the growth-stimulating function results from the muscular action of the clasping male, which helps the immature female to pump blood into her intestine, thereby overcoming a state of relative starvation.
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PMID:The role of Schistosoma mansoni males in feeding and development of female worms. 329 99

The glycogen content of muscle was correlated with the activity of glycogen synthase and glycogen phosphorylase from the parasitic roundworm Ascaris suum maintained in vitro. Adult female worms were maintained in the laboratory in a perfusion system during periods of starvation and feeding. During starvation, the levels of glucogen decreased at a rate of 0.1 to 0.2 mumoles/min/g wet weight of muscle-cuticle. During this time, 95% of the glycogen synthase (E.C. 2.4.1.11) was in the active D-form, and 48% of the phosphorylase (E.C. 2.4.1.1) was in the active a-form. Upon feeding, the rate of incorporation of glycosyl residues into glycogen proceeded at a rate of 0.75 to 1.0 mumoles/min/g muscle-cuticle. Glycogen synthase was 22% in the active I-form and phosphorylase a-levels remained virtually unchanged at 41% as compared with the starved worm. Total levels of both enzymes remained constant over the starvation-feeding period with 3.9 units/g phosphorylase and 0.4 units/g glycogen synthase. The apparent Km value for the substrate UDPG for glycogen synthase was 0.22 +/- 0.02 mM. For glycogen phosphorylase the Km value for G-1-P was 1.76 +/- 0.38 mM.
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PMID:Glycogen metabolizing enzymes during starvation and feeding of Ascaris suum maintained in a perfusion chamber. 679 Jun 95

The effect of low water temperatures on the development and viability of larval and adult Anguillicola crassus (Nematoda) in the final host Anguilla anguilla was studied. European eels were experimentally infected with A. crassus and then maintained for 4 mo at 4, 9, 10, and 19 degrees C. Larval development showed a temperature-dependent pattern and was significantly retarded at low temperatures. Third-stage larvae survived a 4 mo period at 4 degrees C without being affected, although they were not able to invade the swimbladder wall at this temperature. In contrast, adult worms were severely harmed during a 4 mo period at 4 degrees C, as reflected by increased mortality and decreased growth and reproductivity as compared to the worms maintained for the same period at 18 degrees C. Starvation for the eels at 4 mo at 19 degrees C did not affect the development and growth of the nematode. The experimentally obtained results support the hypothesis that the spread of A. crassus in boreal regions, e.g. Northern Europe, is restricted by the natural ambient temperature regimes.
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PMID:Impact of low water temperature on the development of Anguillicola crassus in the final host Anguilla anguilla. 972 3

The dauer larva is an alternative larval stage in Caenorhabditis elegans which allows animals to survive through periods of low food availability. Well-fed worms live for about three weeks, but dauer larvae can live for at least two months without affecting post-dauer lifespan. Mutations in daf-2 and age-1, which produce a dauer constitutive (Daf-C) phenotype, and in clk-1, which are believed to slow metabolism, markedly increase adult lifespan. Here we show that a ctl-1 mutation reduces adult lifespan in otherwise wild-type animals and eliminates the daf-c and clk-1-mediated extension of adult lifespan. ctl-1 encodes an unusual cytosolic catalase; a second gene, ctl-2, encodes a peroxisomal catalase. ctl-1 messenger RNA is increased in dauer larvae and adults with the daf-c mutations. We suggest that the ctl-1 catalase is needed during periods of starvation, as in the dauer larva, and that its misexpression in daf-c and clk-1 adults extends lifespan. Cytosolic catalase may have evolved to protect nematodes from oxidative damage produced during prolonged dormancy before reproductive maturity, or it may represent a general mechanism for permitting organisms to cope with the metabolic changes that accompany starvation.
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PMID:A cytosolic catalase is needed to extend adult lifespan in C. elegans daf-C and clk-1 mutants. 1261 Jun 32

Under adverse conditions, the nematode Caenorhabditis elegans undergoes reversible developmental arrest as dauer larvae, an alternative third larval stage adapted for dispersal and long-term survival. Following such arrest, which may exceed three times their usual life-span, worms resume development to form reproductive adults of normal subsequent longevity. Mutations of genes in the dauer-formation (daf) pathway can extend life-span two- to fourfold, even in adults that mature without diapause. To identify transcript-level changes that might contribute to extended survival, we prepared a subtractive cDNA library of messages more abundant in dauer than in non-dauer (L3) larvae. Six genes were confirmed as three- to ninefold upregulated in dauer larvae, after correction for mRNA load: genes encoding poly(A)-binding protein (PABP), heat-shock proteins hsp70 and hsp90, and three novel genes of uncertain function. The novel genes encode a partial homologue of human activating signal cointegrator 1 (ASC-1), a GTP-binding homologue of a ribosomal protein, and an SH3-domain protein. Transcript levels for all except hsp70 increased during aging in two C. elegans strains, whereas the three novel genes (and possibly PABP) were also induced to varying degrees by starvation of adults. All six genes are expressed at higher levels in young adults of long-lived daf mutant strains than in normal-longevity controls, suggesting that increased expression of these genes may play a protective function, thus favoring survival in diverse contexts.
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PMID:Diverse Caenorhabditis elegans genes that are upregulated in dauer larvae also show elevated transcript levels in long-lived, aged, or starved adults. 1088 42

Regulators of G protein signaling (RGS proteins) inhibit heterotrimeric G protein signaling by activating G protein GTPase activity. Many mammalian RGS proteins are expressed in the brain and can act in vitro on the neural G protein G(o), but the biological purpose of this multiplicity of regulators is not clear. We have analyzed all 13 RGS genes in Caenorhabditis elegans and found that three of them influence the aspect of egg-laying behavior controlled by G(o) signaling. A previously studied RGS protein, EGL-10, affects egg laying under all conditions tested. The other two RGS proteins, RGS-1 and RGS-2, act as G(o) GTPase activators in vitro but, unlike EGL-10, they do not strongly affect egg laying when worms are allowed to feed constantly. However, rgs-1; rgs-2 double mutants fail to rapidly induce egg-laying behavior when refed after starvation. Thus EGL-10 sets baseline levels of signaling, while RGS-1 and RGS-2 appear to redundantly alter signaling to cause appropriate behavioral responses to food.
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PMID:Multiple RGS proteins alter neural G protein signaling to allow C. elegans to rapidly change behavior when fed. 1095 Aug 65


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