Effects Of Energy Deprivation Research Articles

Effect of energy deprivation on metabolite release by anaerobic marine naphthalene-degrading sulfate-reducing bacteria.

The aromatic hydrocarbon naphthalene, which occurs in coal and oil, can be degraded by aerobic or anaerobic microorganisms. A wide-spread electron acceptor for the latter is sulfate. Evidence for in situ naphthalene degradation stems in particular from the detection of 2-naphthoate and [5,6,7,8]-tetrahydro-2-naphthoate in oil field samples. Because such intermediates are usually not detected in laboratory cultures with high sulfate concentrations, one may suppose that conditions in reservoirs, such as sulfate limitation, trigger metabolite release. Indeed, if naphthalene-grown cells of marine sulfate-reducing Deltaproteobacteria (strains NaphS2, NaphS3 and NaphS6) were transferred to sulfate-free medium, they released 2-naphthoate and [5,6,7,8]-tetrahydro-2-naphthoate while still consuming naphthalene. With 2-naphthoate as initial substrate, cells produced [5,6,7,8]-tetrahydro-2-naphthoate and the hydrocarbon, naphthalene, indicating reversibility of the initial naphthalene-metabolizing reaction. The reactions in the absence of sulfate were not coupled to observable growth. Excretion of naphthalene-derived metabolites was also achieved in sulfate-rich medium upon addition of the protonophore carbonyl cyanide4-(trifluoromethoxy)phenylhydrazone or the ATPase inhibitor N,N'-dicyclohexylcarbodiimide. In conclusion, obstruction of electron flow and energy gain by sulfate limitation offers an explanation for the occurrence of naphthalene-derived metabolites in oil reservoirs, and provides a simple experimental tool for gaining insights into the anaerobic naphthalene oxidation pathway from an energetic perspective.

Gender Dimorphism and Lack of Day/Night Variation or Effects of Energy Deprivation on Undercarboxylated Osteocalcin Levels in Humans

ObjectiveUndercarboxylated osteocalcin (ucOC) is a bone marker with potent metabolic effects. Leptin regulates Esp gene expression and osteocalcin carboxylation in animal models. We aim to elucidate day/night patterns of ucOC levels, whether short‐term and/or chronic energy deprivation alters ucOC levels, and whether leptin may mediate these changes in humans.Design and MethodsTwelve healthy males and females were studied for 72 h in the fed state to study day/night pattern of ucOC. The six female subjects were also studied in a crossover interventional study in the fasting state for 72 h with administration of either placebo or metreleptin in physiological doses. Blood samples were obtained hourly from 0800 a.m. on day 3 until 0800 a.m. on day 4. In a separate study, eleven obese subjects who underwent bariatric surgery were followed for 24 weeks to examine the effects of postsurgery weight loss on ucOC levels.ResultsMales have higher ucOC levels compared to females. There is no day/night variation pattern of circulating ucOC in humans. Short‐term and chronic energy deprivation or leptin administrations do not alter ucOC levels.ConclusionsThe hypothesis that ucOC plays a role in energy homeostasis or of leptin in regulating ucOC in humans is not supported.

Loss of folic acid exporter function with markedly augmented folate accumulation in lipophilic antifolate-resistant mammalian cells.

We previously described a 1,000-fold pyrimethamine-resistant Chinese hamster ovary cell line (PyrR100) which retains parental dihydrofolate reductase activity and methotrexate (MTX) sensitivity. This study characterizes the basis for the 14-fold decrease in folic acid and leucovorin concentrations required for clonogenic growth of PyrR100 cells relative to parental AA8 cells. Under conditions in which folic acid reduction was blocked by trimetrexate, PyrR100 cells displayed relative to parental AA8 cells a: 1) 17- and 5-fold increase in the net transport of folic acid and MTX, respectively; 2) 23- and 5-fold decrease in the efflux rate constant for folic acid and MTX, respectively; and 3) 2-fold increase in folic acid influx with no significant change in MTX influx. The markedly increased net folic acid transport in PyrR100 cells could not be explained by cellular folic acid binding, mitochondrial sequestration, polyglutamylation, nor by a decreased membrane potential. The effect of energy deprivation on folic acid and MTX transport in both cell lines was quite different. Glucose and pyruvate deprivation nearly abolished the increase in net folic acid transport in PyrR100 cells. In contrast, energy deprivation increased net MTX transport in AA8 cells, whereas no change was seen with PyrR100 cells. Furthermore, while folic acid influx in PyrR100 and AA8 cells was markedly reduced with energy deprivation, MTX influx was not affected. Provision of glucose and pyruvate to energy-deprived cells resulted in a rapid onset of MTX efflux from parental AA8 cells but not from PyrR100 cells. Taken together these results indicate that the markedly enhanced net transport of folic acid and MTX in PyrR100 cells is largely due to the complete loss of exit pump activity. Furthermore, the energy source that sustains the augmented levels of folic acid appears linked to the influx process and is distinct from the energy source that sustains MTX gradients under these conditions. We conclude that the loss of folic acid efflux is an efficient means of augmenting cellular uptake of folate cofactors and subsequent survival on picomolar folate concentrations. This constitutes the first demonstration of the loss of folic acid exporter activity in mammalian cells as a response to lipophilic antifolate selective pressure.

Effects of energy deprivation induced by fluorocitrate in immortalised rat brain microvessel endothelial cells

Effects of energy deprivation induced by fluorocitrate in immortalised rat brain microvessel endothelial cells

Effects of energy deprivation on the fly pupil mechanism: evidence for a rigor state

The energy dependence of the pupil pigment-migrations in the fly Musca domestica was studied in live animals, using optical techniques and nitrogen-gas induced anoxia. The results obtained can be summarized in 3 points: 1. Energy deficiency can make the pupil mechanism stop in any state, extreme or intermediate. 2. Anoxia induced during intermittent stimulation makes the pupil stop in the closed state (aggregated pigment granules). 3. During long-term anoxia the pupil very slowly opens (dispersal of pigment granules), irrespective of ambient intensity.

Heat-shock proteins maintain the viability of ATP-deprived cells: what is the mechanism?

ATP depletion causes necrosis in mammalian cells. However, a previous heat shock can protect cells from the effects of energy deprivation, probably as a result of the synthesis and accumulation of heat-shock proteins (hsps). We propose that hsps protect ATP-depleted cells from rapid necrotic death by inhibiting the aggregation of cytoskeletal proteins that occurs when ATP synthesis is blocked.

Tumor cell resistance to energy deprivation and hyperthermia can be determined by the actin skeleton stability

The effect of energy deprivation (treatment with rotenone in glucose-free medium) and hyperthermia (44°C) on interphase death of EL-4 thymoma, Ehrlich and HeLa carcinomas was studied in vitro. Irreversible damage accompanied by intensive blebbing with subsequent cell death (necrosis) was observed only when elevation of actin in tritonisoluble fraction occurred although some proteins became insoluble before actin. Actin-specific drugs cytochalasin B and phalloidin accelerated both actin insolubilization and cell necrosis in rotenone-treated EL-4 cells; after conditioning treatment with recovery the actin insolubilization during hyperthermia was suppressed. Ehlrich and HeLa carcinomas were much more resistant to energy deprivation and hyperthermia; this correlated with the resistance of their actin to aggregation. It is concluded that stability of actin skeleton may be determinative of tumor cell resistance to energy deprivation, hyperthermia and possibly to some other treatments.

A cytochemical study on the effects of energy deprivation on autophagocytosis in Ehrlich ascites tumor cells.

The effect of energy deprivation on autophagocytosis in Ehrlich ascites tumor cells was studied using cytochemical techniques. Autophagocytosis was induced with vinblastine incubation (0.1 mM) and the cellular ATP-level was lowered with 2-deoxy-D-glucose (0.35 mM). Acid phosphatase was used as a marker for lysosomal enzymes and imidazole-buffered osmium tetroxide impregnation in order to study the effects of energy deprivation on the maturation of autophagic vacuole (AV) membranes. Control and vinblastine treated cells maintained their ATP-levels throughout the incubation period tested (120 min). 2-Deoxy-D-glucose alone and with vinblastine decreased the intracellular ATP-level significantly after only 3 min incubation. Most of the AV's in control and vinblastine treated cells contained degraded material and acid phosphatase activity. Their membranes were stained only slightly or not at all with imidazole-buffered osmium tetroxide. 2-Deoxy-D-glucose alone as well as with vinblastine induced in particular an accumulation of early stages of AV's. These vacuoles contained undegraded cytoplasmic material and no acid phosphatase activity and their membranes were stained usually partly with imidazole-buffered osmium tetroxide. The membranes of some early AV's resembled endoplasmic reticulum and still had attached ribosomes. It was concluded that the inhibition of cellular energy production used in the present study did not inhibit autophagic sequestration but retarded the maturation of AV membranes and impaired the functioning of lysosomal hydrolases.

Effect of energy deprivation on intracellular transport and secretion of thyroglobulin

The effect of energy deprivation on the intracellular transport and secretion of thyroglobulin was studied in open follicles isolated from porcine thyroids. Follicles were pulse-labeled with 3H-leucine or 3H-galactose. Labeled thyroglobulin was secreted into the incubation medium where it was isolated by means of immunoprecipitation. Secretion was followed in chase incubations under various experimental conditions using CCCP (carbonyl-cyanide-mchlorophenylhydrazone) or DNP (dinitrophenol), both uncouplers of oxidative phosphorylation, or CN−, which inhibits respiration. CCCP (1 μM) was shown to inhibit exocytosis by about 80%, DNP (0.1–5 mM) by 45–85%, and CN− (0.5–1.1 mM) by 5–55%. By combining CN− with the ionophore monensin, which blocks transport through the Golgi complex but does not essentially interfere with exocytosis, evidence was obtained that CN− also inhibits transport of thyroglobulin from the Golgi cisternae to the exocytic vesicles by 40%. Electron-miroscopic autoradiography of isolated thyroid lobes from the rat also indicated that transport of 3H-leucine label into the follicle lumen is inhibited in the presence of CCCP or CN−. Intracellular ATP content was found to be about 40% of the control level in follicles incubated with CCCP (1 uM) or CN− (0.9 mM). The results show that the transport of thyroglobulin from the Golgi complex to the exocytic vesicles as well as from the exocytic vesicles into the follicle lumen is dependent upon metabolic energy. The transport blocks are probably associated with inhibited membrane fusions and fissions.

Effects of energy deprivation and hydrogen peroxide on contraction and myoplasmic free calcium concentrations in isolated myocardial muscle cells.

The effect of energy deprivation and H2O2 on the contraction, shape, and intracellular free Ca2+ concentration of myocardial muscle cells was investigated using suspensions of freshly isolated, electrically stimulated rat ventricle heart cells. The mitochondrial uncoupling agent carbonyl cyanide m-chlorophenylhydrazone (CCCP) was used to decrease the rate of ATP synthesis. At 0.9 mM extracellular Ca2+, CCCP (0.25 microM) reduced the number of contracting cells by 50% after 5 min, and the number of rod-shaped cells by 40% after 10 min. The effects of CCCP were associated with a substantial decrease in measured cellular ATP concentrations. The deleterious effect of exposure of myocytes to CCCP for periods of up to 5 min was enhanced by an increase in the extracellular Ca2+ concentration, but markedly reduced in the absence of electrical stimulation. Verapamil protected myocytes from the deleterious effects of CCCP during the first 5 min but not at later times. In the presence of 46 mM extracellular K+, CCCP caused a marked increase in the myoplasmic free Ca2+ concentration (measured using quin2). This effect was inhibited by verapamil and was not observed in the absence of K+-induced depolarization. Exposure of myocytes to H2O2 (0.5 mM) caused a substantial decrease both in the number of cells which exhibited normal end-to-end synchronous contraction and in the total number of cells which contracted either partially or fully. The effects of H2O2 were more pronounced at higher concentrations of the peroxide, with longer times of exposure to the agent, and at higher concentrations of extracellular Ca2+, and were partially reversed by dimethyl sulfoxide. The results indicate that both ATP deprivation and H2O2, possibly through the generation of free radicals, cause substantial and rapid damage to cardiac myocytes and induce the movement of additional Ca2+ across the sarcolemma to the myoplasm. In the case of ATP deprivation, this initially occurs through voltage-operated channels.

Effects of energy deprivation and a calcium antagonists on function and myoplasmic free calcium concentrations in isolated myocardial muscle cells

Effects of energy deprivation and a calcium antagonists on function and myoplasmic free calcium concentrations in isolated myocardial muscle cells

Studies on the regulation of the biosynthesis of glucose-containing oligosaccharide-lipids. Effect of energy deprivation.

Energy deprivation, induced in thyroid slices by incubation with an uncoupler of oxidative phosphorylation (carbonyl cyanide m-chlorophenylhydrazone) or inhibitors of respiration (N2 or antimycin A), led to a disturbance in oligosaccharide-lipid metabolism which was characterized by a pronounced depletion of the glucosylated (Glc3Man9GlcNAc2) dolichyl pyrophosphoryl saccharide with an attendant accumulation of the Man9GlcNAc2 and, to a lesser extent, the Man8GlcNAc2 lipid-linked species. A concomitant decrease in the N-glycosylation of proteins was furthermore observed. The distribution of lipid-derived oligosaccharides observed by thin layer chromatographic separation was similar whether radiolabeling was achieved by a metabolic ([14C]glucose or [2-3H]mannose incubation) or chemical ([3H]NaBH4) procedure. The latter method proved useful for measuring the levels of individual oligosaccharide-lipids in unincubated tissue, and in this way it was found that unless thyroid was rapidly frozen or immediately immersed in oxygenated medium a marked decrease of glucose-containing oligosaccharide-lipids occurred which could, however, be reversed by a short incubation. The addition of glucose to the slice incubations did not prevent the Man8-9GlcNAc2 accumulation brought about by the inhibitors of energy production, nor did it alter the oligosaccharide-lipid pattern of uninhibited slices. The effect of the inhibitors on metabolically labeled liver slices was similar to that observed in thyroid. The size of the total chloroform/methanol/water (10:10:3)-extractable oligosaccharide-lipid pool (Glc3-Man9GlcNAc2 to Man5GlcNAc2) of thyroid remained quite constant (about 2 nmol/g) regardless of the energy state, and no substantial change in the level of smaller oligosaccharide-lipids, primarily represented by Man2GlcNAc2 (0.5 nmol/g) was evident. Moreover, no change in the total pool sizes was observed in puromycin-treated slices. The possible mechanisms by which energy deprivation leads to an accumulation of the glucose-free oligosaccharide-lipids are evaluated. While it is likely that a selective impairment of glucosylation of newly formed molecules occurs, it is also possible that an imbalance occurs in a postulated glucosyltransferase-glucosidase shuttle with a trapping of the oligosaccharide-lipid in its unglucosylated form.

Anoxia-induced changes in composition and permeability of sarcolemmal membranes in rat heart cell cultures.

The effects of energy-deprivation on composition and permeability of the sarcolemmal membrane of cardiac cells was studied using monolayer cultures of neonatal rat heart cells incubated in the absence of oxygen and metabolic substrates for 0 to 10 h at 37 degrees C. In the course of anoxia the cells were analysed for cholesterol content, a sarcolemmal sterol, and L-leucyl-naphthylamidase (LNA) activity, a sarcolemmal protein. In addition, sarcolemmal permeability was studied by measuring the efflux of alpha-hydroxybutyrate dehydrogenase (HBDH) activity from the incubated cells. To test whether cholesterol and LNA are indeed markers of sarcolemmal membrane of the heart cells used, sarcolemmal preparations were obtained using an isolation method with cation-coated beads. The results of this study indicate that during anoxia and substrate depletion, changes in sarcolemmal cholesterol content precede sarcolemmal LNA liberation and cytoplasmic HBDH release. It is concluded that energy-deprivation in cardiac cells destroys sarcolemmal structure and function, secondary to the loss of cholesterol.

The Influence of Dietary Protein Concentration and Energy Intake on Mitogen Response and Tumor Growth in Melanoma-Bearing Mice

The effects of energy deprivation and low or high dietary protein levels upon lymphocyte transformation of spleen cells from syngeneic tumor-bearing and control mice were studied in a murine model of malignant melanoma. Both T- and B-lymphocyte transformation were significantly stimulated by the presence of a growing melanoma. T-cell responses however, were dependent only upon dietary protein concentrations, not the level of energy intake; whereas, the converse was true for B cells. Moreover, mice fed stock diet had the lowest response to mitogens of all diets tested. Except for mice receiving a 15% casein diet, tumor weights were generally not affected by level of intake or the amount of dietary protein. Others have demonstrated that melanoma cells have a greater need for tyrosine or phenylalanine than other tumor cells; thus we hypothesized that lymphocyte transformation may be depressed by relatively low phenylalanine or tyrosine levels in the diet when protein intakes are limited by either a low dietary concentration a restricted intake of a diet containing adequate protein, or both.

Effects of energy deprivation on Wallerian degeneration in isolated segments of rat peripheral nerve

An acceleration in the progression of Wallerian degeneration was demonstrated in isolated segments of rat peripheral nerve following incubation under energy-deprivational conditions. The additions of1m M cyanide, azide or dinitrophenol to Ringer's incubational solutions brought about granular disintegrative axoplasmic changes, varicosity formation and linear fragmentation of the myelinated nerve fibers within 2–4 h of incubation at 37°C. Incubations in Ringer's solutions without glucose or with the addition of1m M iodoacetate led to identical Wallerian-like degenerative changes of myelinated fibers during the 8–12 h incubational interval. In contrast, the myelinated nerve fibers remained well-preserved following 16 h of incubation in glucose-enriched Ringer's solutions. The progressions of degenerative changes under energy-deprivational conditions were calcium-dependent as evidenced by their failure to occur in calcium-free media. Accordingly, it is believed that an influx of calcium ions into axoplasm is a critical event in bringing about accelerated as well as the natural degradative changes within isolated nerve fibers. It would follow that the maintenance of axolemmal integrity, especially the calcium-excluding mechanism(s), is an active process which utilizes energy and is vulnerable to energy-deprivational conditions.