Influence of oxygen tension on the respiratory activity of Mycobacterium phlei

Growth of Mycobacterium phlei under low oxygen tension resulted in specific activities two to twenty times lower for formate dehydrogenase, malate dehydrogenase, beta-hydroxybutyrate dehydrogenase, lactate oxidase and NADH dehydrogenase than when cultures were grown under high aeration. An increase in fumarate reductase and succinate dehydrogenase occurred with M. phlei grown under low oxygen tension. Malate: vitamin K dehydrogenase and glucose-6-phosphate dehydrogenase activity were not significantly affected by the oxygen tension used to grow the bacteria, and neither culture contained a lactate dehydrogenase. With growth of M. phlei in conditions of low oxygen tension, cytochrome a was not detected, but cytochrome b was prominent in membranes and cytochrome c was present in the soluble fraction.     

Microphotometric measurement of some enzymatic activities in rabbit spermatozoa during epididymal maturation

Cytochemical quantitative measurements of isocitrate dehydrogenase (ICDH), malate dehydrogenase (MDH), cytochrome oxidase, lactate dehydrogenase (LDH), glucose 6-phosphate dehydrogenase (G6PDH) and glutamate dehydrogenase (GLDH) activities were made on rabbit spermatozoa collected from the testis, the different epididymal sites and the ductus deferens. These measurements were made on individual spermatozoa (at least 100 spermatozoa for each site under consideration) using a Vickers M 85 scanning microdensitometer.The activity patterns of the enzymes involved in the tricarboxylic acid cycle (ICDH, MDH) and in the respiratory chain (cytochrome oxidase) both showed a progressive decrease in the intramitochondrial oxidative metabolism from the testis to the ductus deferens. This was in contrast to LDH activity which represents the anaerobic glycolysis pathway rather than the activity of intramitochondrial LDH. The G6PDH activity could be related to those membrane modifications which the male gamete undergoes during its epididymal maturation. Potential GLDH activity was relatively intense in the spermatozoa from the testis and from the initial and distal segments of the genital tract, suggesting an intramitochondrial synthesis of enzymes such as cytochrome oxidase or ATPase.The quantitative variations of the enzymatic activities occurring during the transit of spermatozoa along the male genital tract suggested the existence of different specific interactions between the spermatozoon and the epididymal microenvironment.     

Metabolic background for establishment of the subpopulation structure in early ontogenesis in the Atlantic salmon (the case of energy of carbohydrate metabolism)

The activity of some enzymes involved in energy and carbohydrate metabolism was studied in Atlantic salmon embryos at the eyed egg stage and in salmon fingerlings (0+) from two trophic–ecological groups: the Varzuga River bed and two tributaries, the Pyatka and Sobachii rivers (Kola Peninsula). It has been demonstrated that heterogeneity of embryos was most evident in the case of cytochrome c oxidase (CO), malate dehydrogenase (MDH), glycerol-1-phosphate dehydrogenase (G1PDH), and glucose-6-phosphate dehydrogenase (G6PDH), while the lowest level of heterogeneity was observed for lactate dehydrogenase (LDH) and aldolase. A positive correlation was revealed between the activities of CO, LDH, MDH, and G1PDH. It was noted that G6PDH showed a negative correlation with almost all enzymes under study. It was found that salmon juveniles inhabiting the tributaries were characterized by high LDH, aldolase, and G1PDH activity and lower activity of G6PDH compared to the juveniles inhabiting the main river bed. Notably, the differences in the activity of the enzymes involved in aerobic metabolism between the two groups of fingerlings under analysis were observed only in the autumn.     

Perturbations in carbohydrate metabolism during cypermethrin toxicity in fish, Tilapia mossambica

Sublethal concentrations (0.04 ppm) of cypermethrin induced significant metabolic changes in brain, liver and gill tissues of fish, T. mossambica. While cypermethrin caused depletion in glycogen and pyruvate levels lactate content was elevated in all the tissues. While phosphorylase 'a' and aldolase activity increased, phosphorylase 'b' activity registered a decrease in the present study. A decrease in lactate dehydrogenase activity with increase in lactate levels suggests reduced mobilization of pyruvate into citric acid cycle. Glucose-6-phosphate dehydrogenase activity was also elevated indicating enhanced oxidation through HMP pathway during cypermethrin toxicity. Inhibition of succinate, malate and isocitrate dehydrogenases and cytochrome c oxidase activity indicates impaired oxidation of carbohydrates through citric acid cycle.     

Metabolic and physiological responses in tissues of the long-lived bivalve Arctica islandica to oxygen deficiency

In Arctica islandica, a long lifespan is associated with low metabolic activity, and with a pronounced tolerance to low environmental oxygen. In order to study metabolic and physiological responses to low oxygen conditions vs. no oxygen in mantle, gill, adductor muscle and hemocytes of the ocean quahog, specimens from the German Bight were maintained for 3.5 days under normoxia (21 kPa=controls), hypoxia (2 kPa) or anoxia (0 kPa). Tissue levels of anaerobic metabolites octopine, lactate and succinate as well as specific activities of octopine dehydrogenase (ODH) and lactate dehydrogenase (LDH) were unaffected by hypoxic incubation, suggesting that the metabolism of A. islandica remains fully aerobic down to environmental oxygen levels of 2 kPa. PO(2)-dependent respiration rates of isolated gills indicated the onset of metabolic rate depression (MRD) below 5 kPa in A. islandica, while anaerobiosis was switched on in bivalve tissues only at anoxia. Tissue-specific levels of glutathione (GSH), a scavenger of reactive oxygen species (ROS), indicate no anticipatory antioxidant response takes place under experimental hypoxia and anoxia exposure. Highest specific ODH activity and a mean ODH/LDH ratio of 95 in the adductor muscle contrasted with maximal specific LDH activity and a mean ODH/LDH ratio of 0.3 in hemocytes. These differences in anaerobic enzyme activity patterns indicate that LDH and ODH play specific roles in different tissues of A. islandica which are likely to economize metabolism during anoxia and reoxygenation.     

Histochemical studies of fibroblasts from patients with Menkes kinky hair disease and Wilson's disease

Summary Cultured fibroblasts from Menkes kinky hair disease patients showed markedly reduced succinate dehydrogenase and amine oxidase activities. Cytochrome oxidase activity, however, was greatly reduced in some cells and almost normal in others. Cultured fibroblasts from patients with Wilson's disease showed moderately reduced succinate dehydrogenase and cytochrome oxidase activities. Amine oxidase activity was only slightly reduced when compared to that of normal. These results indicated that the histochemical phenotype observed in fibroblasts from patients with Menkes kinky hair disease and Wilson's disease were distinctly different from each other and from normal fibroblasts.     

Studies on rat liver mitochondria: 4. Enzyme activities in mitochondria preserved at 0-4 degrees C

Rat liver mitochondria, stored with the energy-linked functions preserved or in aging conditions, were used to assay the activity of various enzymes during five days. The preservation of energy-linked functions was monitored by the respiratory control coefficient. ATPase, cytochrome oxidase and NADH dehydrogenase showed increased activity when the energy-linked functions were preserved. In aging conditions, cytochrome oxidase, NADH dehydrogenase and ATPase showed decreased activity. The ATPase activity increased only when mitochondria were stored in the presence of inhibitors of the electron transport chain. The activity of NADH oxidase did not change, and succinate oxidase and succinate dehydrogenase showed a small decrease in their activity. The enzymes of the matrix, alpha-ketoglutarate dehydrogenase, malate dehydrogenase and aspartate aminotransferase showed little decrease in activity under either of the conditions of storage. The total protein content decreased slightly under both conditions of storage. These results show that the activity of the enzymes analysed was maintained at reasonable levels, when the energy-linked functions of isolated mitochondria were preserved.     

Changes in the activity of different classes of enzymes in the cerebral cortex of rats in ontogeny and after the transplantation of embryonic nerve tissue

The activity of lactate dehydrogenase (LDH), indophenol oxidase, aspartate aminotransferase (AsAT), alkaline phosphatase, acid phosphatase and aldolase at different stages of rat development was measured. We have also determined changes in the activity of these enzymes resulting from transplantation of embryonic nerve tissue (ENT) into the brain of adult animals. During development from the embryo to the adult animal, LDH and AsAT activities increased, while alkaline phosphatase activity diminished. After ENT transplantation, the most prominent changes were in the alkaline phosphatase activity whereas the activity of LDH, AsAT and acid phosphatase remained unchanged and similar to that in the brain cortex of intact adult animals. Changes in the enzyme activity resulting from ENT transplantation changed in a manner characteristic of the transplant. Local brain damage did not change the activity of the studied enzymes fifty days after surgery.     

Membrane-bound respiratory of Spirillum itersonii.

The membrane-bound respiratory system of the gram-negative bacterium Spirillum itersonii was investigated. It contains cytochromes b (558), c (550), and o (558) and beta-dihydro-nicotinamide adenine dinucleotide (NADH) and succinate oxidase activities under all growth conditions. It is also capable of producing D-lactate and alpha-glycerophosphate dehydrogenases when grown with lactate or glycerol as sole carbon source. Membrane-bound malate dehydrogenase was not detectable under any conditions, although there is high activity of soluble nicotinamide adenine dinucleotide: malate dehydrogenase. When grown with oxygen as the sole terminal electron acceptor, approximately 60% of the total b-type cytochrome is present as cytochrome o, whereas only 40% is present as cytochrome o in cells grown with nitrate in the presence of oxygen. Both NADH and succinate oxidase are inhibited by azide, cyanide, antimycin A, and 2-n-heptyl-4-hydroxyquinoline-N-oxidase at low concentrations. The ability of these inhibitors to completely inhibit oxidase activity at low concentrations and their effects upon the aerobic steady-state reduction levels of b- and c-type cytochromes as well as the aerobic steady-state reduction levels obtained with NADH, succinate, and ascorbate-dichlorophenolindophenol suggest that presence of an unbranched respiratory chain in S. itersonii with the order ubiquinone leads to b leads to c leads to c leads to oxygen.     

Differential expression of the three yeast glyceraldehyde-3-phosphate dehydrogenase genes

Utilizing yeast strains containing insertion mutations in each of the three glyceraldehyde-3-phosphate dehydrogenase structural genes, the level of expression of each gene was determined in logarithmically growing cells. The contribution of the TDH1, TDH2, and TDH3 gene products to the total glyceraldehyde-3-phosphate dehydrogenase activity in wild type cells is 10-15, 25-30, and 50-60%, respectively. The relative proportions of expression of each gene is the same in cells grown in the presence of glucose or ethanol as carbon source although the total glyceraldehyde-3-phosphate dehydrogenase activity in cells grown in the presence of glucose is 2-fold higher than in cells grown on ethanol. The polypeptides encoded by each of the structural genes were identified by two-dimensional polyacrylamide gel electrophoresis. The TDH3 structural gene encodes two resolvable forms of glyceraldehyde-3-phosphate dehydrogenase which differ by their net charge. The apparent specific activity of glyceraldehyde-3-phosphate dehydrogenase encoded by the TDH3 structural gene is severalfold lower than the enzymes encoded by TDH1 or TDH2. The polypeptides encoded by the TDH2 or TDH3 structural genes form catalytically active homotetramers. The apparent Vmax for the homotetramer encoded by TDH3 is 2-3-fold lower than the homotetramer encoded by TDH2. Evidence is presented that isozymes of glyceraldehyde-3-phosphate dehydrogenase exist in yeast cells, however, the number of different isozymes formed was not established. These data confirm that the three yeast glyceraldehyde-3-phosphate dehydrogenase genes encode catalytically active enzyme and that the genes are expressed at different levels during logarithmic cell growth.     

Effect of aeration intensity on the biochemical composition of baker's yeast. II. Activities of the oxidative enzymes

When the effect of catabolite repression is eliminated Saccharomyces cerevisiae prefers an aerobic metabolism. The potential for completely aerobic catabolism exists even in circumstances where its action is limited by the oxygen available. When the oxygen absorption in the medium is adequate, yeast uses a solely oxidative metabolism for energy-yielding reactions. The changes observed in the activity of malate dehydrogenase can be described as a function of two isoenzymes, both of which are affected by oxygen; the isoenzyme participating in the glyoxylate cycle shows variations in activity similar to that observed in isocitrate lyase. NAD-linked glutamate dehydrogenase activity roughly follows that of malate dehydrogenase and isocitrate lyase; in cultivations with the same growth rate the NADP-linked dehydrogenase is insensitive to the oxygen level. The cytochromes aa₃, b, and c have a clear maximum at low oxygen tension, the most sensitive being cytochrome aa₃. The imbalance between cytochrome c:oxygen oxidoreductase activity and the amount of cytochrome aa₃, and the correlation observed between respiration rate and the activities of cytochrome c oxidase and NADH₂:cytochroine c oxidoreductase are discussed. Methods used for estimation of cytochromes are compared.     

Relationship between the activity of the succinoxidase system and the rate of oxygen consumption during the embryonic development of the mealworm,Tenebrio molitor Linnaeus

1. Readings were made on the rates of oxygen consumption and on the activities of the succinoxidase system of eggs of the mealworm for each day of embryonic development at 30°C. 2. The rate of oxygen consumption, expressed as microliters/50 eggs/hour, was low (4.89) in newly laid eggs. It rose to 7.41 during the next 24 hours, remained at this level for the next 2 days, and then increased during the remainder of the embryonic period reaching a high value of 14.79 at the time of hatching. 3. The activity of cytochrome oxidase in eggs from newly emerged beetles, expressed as Δ log [Cy Fe⁺⁺]/minute, remained at a value of 0.042 during the first half of the embryonic period, increasing to 0.233 during the latter half of this period. 4. The activity of succinic dehydrogenase showed the same series of changes except at much lower values. Expressed as Δ log [Cy Fe⁺⁺⁺]/minute, they ranged from 0.010 in the newly laid egg to 0.034 at the end of the embryonic period. 5. The activity of cytochrome oxidase of the egg was found to decrease with parental age. Eggs from newly emerged beetles had activity values considerably higher than those of beetles 6 or 8 weeks after emergence. However, no comparable changes were noted in the activity of succinic dehydrogenase or in the rate of oxygen consumption. These observations suggest that cytochrome oxidase is not a rate-limiting enzyme in the respiratory metabolism of the mealworm egg.     

A biochemically distinct form of cytochrome oxidase (COX) deficiency in the Saguenay-Lac-Saint-Jean region of Quebec.

We report the results of biochemical and molecular investigations on a group of patients from the Saguenay-Lac-Saint-Jean region of Quebec who have an unusual form of cytochrome oxidase deficiency and Leigh disease. This group can be distinguished from the classical presentation of cytochrome oxidase deficiency with Leigh disease, by the severity of the biochemical defect in different tissues. The activity in skin fibroblasts, amniocytes, and skeletal muscle of cytochrome oxidase is 50% of normal, while in kidney and heart it is close to normal values. Brain and liver, on the other hand, have very low activities. The defect in activity appears to result from a failure of assembly of the cytochrome oxidase complex in liver, but levels of mRNA for both mitochondrially encoded and nuclear-encoded subunits in liver and skin fibroblasts were found to be the same as those in controls. The cDNA sequence of the liver-specific cytochrome oxidase subunits VIa and VIIa were determined in samples from patient liver and skin fibroblasts and showed normal coding sequence.     

Relative Activities and Characteristics of Some Oxidative Respiratory Enzymes from Conidia of Verticillium albo-atrum

Conidia of Verticillium albo-atrum Reinke and Berthold, collected from shake cultures grown in Czapek broth, were sonified for 4 or 8 minutes or ground frozen in a mortar to obtain cell-free homogenates. These were assayed for certain enzymes associated with respiratory pathways. Malic dehydrogenase was the most active, glucose-6-P and NADH dehydrogenase were less active, NADH-cytochrome c reductase, NADPH dehydrogenase, and cytochrome oxidase were low in activity, and succinic dehydrogenase and succinic cytochrome c reductase were very low to negligible in activity. No NADH oxidase activity was detected.

With the exception of NADH-cytochrome c reductase and possibly succinic dehydrogenase and cytochrome c reductase, there was no evident increase in specific activity of the enzymes during germination. Some NADH-cytochrome c reductase and a small amount of succinic-dehydrogenase and cytochrome c reductase were associated with the particulate fraction from 105,000 × g centrifugation. The other enzymes, including cytochrome oxidase, almost completely remained in the supernatant fraction.

Menadione and vitamin K-S(II) markedly stimulated NADH-cytochrome c reductase activity in the supernatant fraction but had much less effect on NADPH-cytochrome c reductase in this fraction or on either of these enzyme systems in the particulate fraction. Electron transport inhibitors affected particulate NADH- and NADPH-cytochrome c reductase activity but had no effect on these in the supernatant fraction.

     

Behaviour of some mitochondrial enzymes in ripening tomato fruit

The activities of four mitochondrial enzymes were studied in four stages of ripening tomato fruit. The highest enzyme activity was recorded for malate dehydrogenase followed by cytochrome c oxidase. Succinate dehydrogenase and NADH oxidase levels were low and could only be determined in the green stage of the fruit. However, peaks of various enzyme activities coincided in identical mitochondrial fractions on the sucrose density gradient. Moreover, the levels of malate dehydrogenase and cytochrome c oxidase were constant during the ripening process while the other two enzymes, succinate dehydrogenase and NADH oxidase, declined. This might indicate that mitochondria retain some of their essential functions through the ripening process.     

Myeloperoxidase-mediated damage to the succinate oxidase system of Escherichia coli. Evidence for selective inactivation of the dehydrogenase component

Myeloperoxidase, a granule-associated enzyme of neutrophils and monocytes, combines with H2O2 and chloride to form a potent microbicidal system that contributes to phagocyte antimicrobial activity. The nature of the lesion or lesions induced by the myeloperoxidase system which are responsible for the loss of microbial replicative activity (viability) remains unknown. Using Escherichia coli grown to late log or stationary phase under conditions of low aeration with succinate as the sole carbon source, we found that myeloperoxidase-induced loss of microbial viability could be correlated with a decrease in succinate-dependent respiration (succinate oxidase activity). Succinate dehydrogenase activity fell rapidly to undetectable levels during incubation with the myeloperoxidase system, suggesting that damage to the dehydrogenase was a major factor in the loss of oxidase activity. Other components of the succinate oxidase system were resistant to the actions of myeloperoxidase. The ubiquinone-8 and cytochrome components of the respiratory chain remained nearly constant in amount despite reduction of respiration to undetectable levels. However, as expected from the loss of succinate dehydrogenase activity, succinate-ubiquinone reductase and succinate-cytochrome reductase activities were markedly impaired. We propose that the loss of E. coli viability induced by the myeloperoxidase-H2O2-chloride system is due in part to the loss of electron transport function consequent to the oxidation of critical catalytic centers in susceptible dehydrogenases.     

Studies on the nephrotoxicity of p-nitrophenylarsonic acid: changes in rat kidney and urinary enzyme activities following the administration of p-nitrophenylarsonic acid.

Histological studies showed that the administration of p-nitrophenylarsonic acid to rats resulted in renal tubular necrosis. The nephrotoxin was administered intraperitoneally and doses greater than 30 mg/kg were found to be fatal. The severity of the renal lesion depended on the amount of the nephrotoxin used. Elevated serum urea levels, urinary protein and volume were recorded over an 8-day period following the injection of the nephrotoxin. These changes were paralleled by an increase in the activity of lactate dehydrogenase, acid and alkaline phosphatase, N-acetyl-beta-glucosaminidase and beta-glucosidase in the urine. beta-Glycosidase activities increased in kidney homogenates, immediately after the injection of the nephrotoxin, but this eventually fell to well below the normal range. Subcellular fractions were prepared from sucrose homogenates by differential centrifugation and beta-glycosidases and cytochrome oxidase were used as enzyme markers. Only minor changes in the activity of cytochrome oxidase activity resulted from the administration of p-nitrophenylarsonic acid. One of the earliest indications of renal damage was a decrease in lysosomal latency. The activities of the lysosomal and soluble enzymes were elevated above normal during the first two days after the injection of p-nitrophenylarsonic acid, but they fell to values, significantly lower than normal, on the third day. The isoenzymic forms of beta-galactosidase, beta-glucosidase and N-acetyl-beta-glucosaminidase in normal and damaged kidneys were studied, using starch gel electrophoresis. The activities of both the lysosomal and the soluble forms of these enzymes decreased following the injection of the nephrotoxin, confirming the results obtained with whole homogenates. The relationship between the changes in renal enzyme activity and urinary enzyme excretion during the nephrotoxic process is discussed.     

Activity of cytochrome c oxidase and lactate dehydrogenase in muscle tissue of slow growing (lower modal group) and fast growing (upper modal group) Atlantic salmon

Fast growing Atlantic salmon (upper modal group) exhibit a higher activity of muscle cytochrome c oxidase (CCO) and lactate dehydrogenase (LDH) than the slow growing salmon (lower modal group). The ratios of CCO/LDH activity, indicate a higher aerobic/anaerobic metabolic potential of the axial muscle in the upper modal group.     

Oxygen consumption and cytochrome oxidase activity of muscle tissue from the limbs of axolotls following restoration of regenerative capability suppressed by x-ray irradiation]

The intensity of oxygen consumption and the activity of cytochrome oxidase have been studied in the homogenate, mitochondria and nuclei of the limb muscle tissue in axolotls after the suppression of regenerative ability by X-irradiation and its experimental restoration. Under the suppression of regenerative ability, the oxygen consumption was inhibited. The cytochrome oxidase activity in the homogenate and mitochondria decreased and in the nuclei remained at the same level or even increased as compared with the intact limb. Under the restoration of regenerative ability, the intensity of respiration of the homogenate and mitochondria increased and this increase was accompanied by the increase of the cytochrome oxidase activity. The activity of cytochrome oxidase in the nuclei did not change at the stage of blastema and sharply fell at the stage of formed limb.