Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ultrastructure of the mid-gut cells of female Nasonia vitripennis is described. The mid-gut consists of a uniform, single-cell epithelium. The cells of different gut regions were analysed using morphometric techniques in order to determine any differences in the components. The structure of the cells is described in the unfed animal, and after varying periods of feeding on host body-fluids. Tissues were sampled after 12 h and 24 h of feeding on host body-fluids and after 24 h feeding/24 h starvation. The cells were found to be complex and contain an organelle component that allows solute-transport and extensive lipid synthesis. A limited cytochemical analysis involving the lysosomal marker enzyme-acid phosphatase--and the respiratory enzyme--cytochrome oxidase was carried out.
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PMID:The ultrastructure of the mid-gut cells of Nasonia vitripennis (Walker) (Hymenoptera, Pteromalidae). 18 30

An analysis of starvation and starvation followed by refeeding was undertaken to characterize some organismic, organ, and mitochondrial responses to these two circumstances. Body weight, organismic respiration as well as weight protein and succinic dehydrogenase activity for liver, kidney, and heart were determined over the course of 6 days of starvation and 5 days refeeding for adult male rats. Assays of marker enzyme activities for mitochondria (cytochrome oxidase), lysosomes (acid phosphatase), endoplasmic reticulum (glucose-6-phosphatase), and plasma membranes (5'-nucleotidase) were conducted for liver in addition to quantitations of mitochondrial protein. All enzyme determinations were done on whole tissue homogenates and reported as total organ activity. Liver mitochondria were harvested quantitatively directly from whole liver homogenates by zonal centrifugation for determination of mitochondrial protein. Starvation resulted in a major loss of body weight, organ weight, and organ protein; liver greater than kidney greater than heart. These changes were accompanied by a major reduction in organ succinic dehydrogenase activity; liver greater than kidney. In heart, succinic dehydrogenase was doubled in activity at day 2 of starvation and subsequently diminished to values not significantly lower than controls. In liver, mitochondrial mass (protein) was severely diminished. From analysis of marker enzyme activities, it appeared that lysosomes, endoplasmic reticulum, and plasma membrane were also decreased. Refeeding restored the greatest part of these losses within 5 days.
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PMID:Starvation and refeeding in rats: effect on organismic respiration, cytoplasmic constituents of liver, and succinic dehydrogenase activity in liver, kidney, and heart. 70 2

The levels of transcripts for Neurospora crassa genes concerned with cellular and metabolic functions changed dramatically at different stages of asexual development. Transcripts for some conidiation-related (con) genes were present at high levels in conidiating cultures and in dormant conidia, but were absent or reduced during mycelial growth. Levels of some con transcripts increased transiently during conidial germination, while others disappeared. Transcripts for amino acid biosynthetic enzymes, ribosomal proteins, cytochrome oxidase subunits, histones, and other polypeptides important for cell growth were detected in newly formed conidia and were present at reduced levels in dormant conidia. Levels of these transcripts increased upon germination of wild-type conidia in minimal medium, reaching their highest levels during this stage or during the early phase of exponential growth. The increased transcription of amino acid biosynthetic genes observed during germination in minimal medium was not dependent on a functional cpc-1 gene. However, cpc-1, which encodes a DNA binding protein presumed to function as a transcriptional activator, was essential for increased expression of amino acid biosynthetic genes when amino acid starvation was imposed during germination or at any subsequent stage of mycelial growth.
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PMID:Developmental expression of genes involved in conidiation and amino acid biosynthesis in Neurospora crassa. 183 95

The mobilization of stored carbohydrates (sucrose and starch) during sucrose starvation was studied with sycamore (Acer pseudoplatanus) cells. When sucrose was omitted from the nutrient medium, vacuolar sucrose was first consumed. When a threshold of intracellular sucrose concentration was attained the cytoplasmic phosphorylated compounds decreased whereas cytoplasmic Pi increased symmetrically. Such a situation triggered starch breakdown. When almost all the intracellular sucrose pool had disappeared, the cell respiration rates (normal and uncoupled) declined progressively. The decrease in the rate of respiration triggered by sucrose starvation was attributable neither to the availability of substrate for mitochondrial respiration nor to a decrease in the maximal rate of O2 consumption by mitochondria expressed in terms of nanomole of O2 consumed per min/mg of mitochondrial protein. In fact, the uncoupled respiration rates decreased in parallel with the decrease in total intracellular cardiolipin or cytochrome aa3. These results demonstrate therefore that after a long period of sucrose starvation the progressive decrease in the uncoupled rate of O2 consumption by sycamore cells was attributable to a progressive diminution of the number of mitochondria/cell.
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PMID:Biochemical changes during sucrose deprivation in higher plant cells. 300 85

Steady-state levels of the mitochondrial (mt) mRNA encoding subunit II of cytochrome oxidase (COII) were increased 5-10 fold in fully transformed cell lines derived from rodent embryonic fibroblasts after transfer of polyoma virus DNA, and in immortalized cell lines established by transfer of plt (polyoma large T protein), E1A (adenovirus) and myc oncogenes. Increased mitochondrial gene expression was not related with active growth per se: it was low in fast-growing rat embryo cells, and it did not change upon serum starvation and subsequent stimulation of FR3T3 cells. The number of copies of mtDNA did not vary, and different mitochondrial mRNAs and rRNAs were increased in the same proportions, suggesting a change in the rate of accumulation of their common precursor.
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PMID:Increased levels of mitochondrial gene expression in rat fibroblast cells immortalized or transformed by viral and cellular oncogenes. 301 94

Postnuclear supernates from homogenates of skeletal muscle from rats subjected to starvation, injections of Triton WR-1339, dextran-500, and dextran + corticosterone were fractionated by means of rate and isopycnic zonal centrifugation in sucrose-0.02 M KCl gradients. Zonal fractions were analyzed for protein, RNA, cytochrome oxidase, and up to six acid hydrolases. The results indicate the presence of two groups of lysosome-like particles. One group contributes approximately 95% of the cathepsin D and acid phosphatase activity and 75% of the acid ribonuclease, beta-glucuronidase, and arylsulfatase activity in muscle. It is characterized by a modal equilibrium density of 1.18 that is decreased by starvation, but is not shifted by dextran-500 or Triton WR-1339. The second group has a higher proportion of acid ribonuclease, beta-glucuronidase, and arylsulftase; the equilibrium density can be shifted by dextran-500 and Triton WR-1339. It is suggested that this group of lysosomes is derived from macrophages and other connective tissue cells, whereas the former group represents lysosome-like particles from muscle cells.
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PMID:Lysosomes in skeletal muscle tissue. Zonal centrifugation evidence for multiple cellular sources. 432 73

Transcriptional lacZ fusions have been used to analyze the regulation of the appA operon of Escherichia coli. The appA operon contains the genes cyxA and cyxB, coding for the putative third cytochrome oxidase, and appA, encoding acid phosphatase. The analysis showed that the cyxAB and the appA genes are cotranscribed from a potentially strong promoter, Pcyx, located immediately upstream of cyxA and that the operon in addition contains an internal promoter, PappA, contributing significantly to the transcription of the appA gene. The two promoters were both induced by starvation for Pi and by entry into stationary phase. The cyx promoter was in addition found to be activated by anaerobic growth conditions. The product of the previously identified appY gene, which when present on a high-copy-number plasmid stimulates synthesis of acid phosphatase, was shown to activate the cyx promoter. An insertion mutation in the appY gene was constructed in vitro and recombined into the chromosome. The appY mutation eliminated induction of the cyx promoter by anaerobiosis and severely reduced induction of this promoter by phosphate starvation and upon entry into stationary phase but had no effect on induction of the appA promoter. The appY mutation had no effect on survival in stationary phase, nor did it have any effect on growth rate or yield under aerobic or anaerobic conditions. The possibility that AppY is a third global regulator of energy metabolism genes is discussed.
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PMID:Role of the transcriptional activator AppY in regulation of the cyx appA operon of Escherichia coli by anaerobiosis, phosphate starvation, and growth phase. 807 Dec 19

The expression and transcriptional regulation of the Escherichia coli cyx-appA operon and the appY gene have been investigated under different environmental conditions with single-copy transcriptional lacZ fusions. The cyx-appA operon encodes acid phosphatase and a putative cytochrome oxidase. ArcA and AppY activated transcription of the cyx-appA operon during entry into stationary phase and under anaerobic growth conditions. The expression of the cyx-appA operon was affected by the anaerobic energy metabolism. The presence of the electron acceptors nitrate and fumarate repressed the expression of the cyx-appA operon. The nitrate repression was partially dependent on NarL. A high level of expression of the operon was obtained in glucose medium supplemented with formate, in which E. coli obtains energy by fermentation. The formate induction was independent of the fhlA gene product. The results presented in this paper indicate a clear difference in the regulation of the cyx-appA operon and that of the cyd operon, encoding the cytochrome d oxidase complex. The results suggest that cytochrome x oxidase has a function under even more-oxygen-limiting conditions than cytochrome d oxidase. The expression of the appY gene is induced immediately by anaerobiosis, and this anaerobic induction is independent of Fnr, and AppY, but dependent on ArcA. The expression of the appY gene is not affected significantly by the anaerobic energy metabolism, i.e., fermentation versus anaerobic respiration. A model incorporating the anaerobic regulation of the appY gene and the two operons which are controlled by AppY, the hydrogenase 1 (hya) operon and the acid phosphatase (cyx-appA) operon, is presented. The expression of the appY gene is inversely correlated with the growth rate and is induced by phosphate starvation as well as during entry into stationary phase. During oxygen-limiting conditions the stationary-phase induction is partially dependent on ArcA. The alternative sigma factor sigma S has limited influence on the transcription of the appY gene during entry into stationary phase and no effect on the induction by phosphate starvation.
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PMID:Effect of growth conditions on expression of the acid phosphatase (cyx-appA) operon and the appY gene, which encodes a transcriptional activator of Escherichia coli. 862 81

Physiological and biochemical measurements were performed on six oyster (Crassostrea gigas) cohorts, in order to: (a) investigate the whole-body response (growth, energy content, metabolic and excretion rates) of 2-week-old postlarvae (spat) to enforced (0-8 days) starvation, and (b) test the potential use of three aerobic enzyme systems as indices of physiological condition. Starvation resulted in exponential reduction of postlarval metabolic and excretion rates, as well as a linear decrease in enzyme activity. These response mechanisms effectively limited the loss of endogenous reserves after 2 days of starvation and maintained the oyster's functional integrity over prolonged (8 days) starvation. Proteins appeared to be selectively conserved during short-term (2 days) starvation, as suggested by a decrease in total protein content, while maintaining constant weight-specific enzyme activity. Postlarvae starved for 2 days exhibited relatively higher lipid losses, lower mortality and lower metabolism than metamorphosing stages, thus suggesting a greater buffering capacity to starvation in the former. The activity of the electron transport system may be a useful indicator of long-term stress or developmental condition of oyster postlarvae, while citrate synthase and cytochrome oxidase could be used as indicators of growth rate. None of these enzyme systems is recommended as an index of aerobic metabolism during short-term starvation.
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PMID:Metabolic depression and whole-body response to enforced starvation by Crassostrea gigas postlarvae. 1216 Aug 73

The effects of increasing mitochondrial oxidative phosphorylation (OXPHOS), by enhancing electron transport chain components, were evaluated on 1-methyl-4-phenylpyridinium (MPP+) toxicity in brain neuroblastoma cells. Although glucose is a direct energy source, ultimately nicotinamide and flavin reducing equivalents fuel ATP produced through OXPHOS. The findings indicate that cell respiration/mitochondrial O(2) consumption (MOC) (in cells not treated with MPP+) is not controlled by the supply of glucose, coenzyme Q(10) (Co-Q(10)), NADH+, NAD or nicotinic acid. In contrast, MOC in whole cells is highly regulated by the supply of flavins: riboflavin, flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), where cell respiration reached up to 410% of controls. In isolated mitochondria, FAD and FMN drastically increased complex I rate of reaction (1300%) and (450%), respectively, having no effects on complex II or III. MPP+ reduced MOC in whole cells in a dose-dependent manner. In isolated mitochondria, MPP+ exerted mild inhibition at complex I, negligible effects on complexes II-III, and extensive inhibition of complex IV. Kinetic analysis of complex I revealed that MPP+ was competitive with NADH, and partially reversible by FAD and FMN. Co-Q(10) potentiated complex II ( approximately 200%), but not complex I or III. Despite positive influence of flavins and Co-Q(10) on complexes I-II function, neither protected against MPP+ toxicity, indicating inhibition of complex IV as the predominant target. The nicotinamides and glucose prevented MPP+ toxicity by fueling anaerobic glycolysis, evident by accumulation of lactate in the absence of MOC. The data also define a clear anomaly of neuroblastoma, indicating a preference for anaerobic conditions, and an adverse response to aerobic. An increase in CO(2), CO(2)/O(2) ratio, mitochondrial inhibition or O(2) deprivation was not directly toxic, but activated metabolism through glycolysis prompting depletion of glucose and starvation. In conclusion, the results of this study indicate that the mechanism of action for MPP+, involves the inhibition of complex I and and more specifically complex IV, leading to impaired OXPHOS and MOC. Moreover, flavin dervatives control the rate of complex I/cellular respiration and Co-Q10 augments complex II [corrected].
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PMID:Effects of enhancing mitochondrial oxidative phosphorylation with reducing equivalents and ubiquinone on 1-methyl-4-phenylpyridinium toxicity and complex I-IV damage in neuroblastoma cells. 1500 52


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