Comparative levels of muscle glycolytic enzymes in mammals, fish, echinoderm and molluscs.

1. Levels of glycolytic enzymes were determined in terms of units of enzyme/mg protein in rat striated muscle, carp lateral muscle, holothuria longitudinal muscle of the body wall, and a snail foot muscle. 2. An attempt has been made to correlate levels of glycolytic enzymes as a parameter to establish a "biochemical distance" at molecular level and correlate this with the phylogenetic position in animals sufficiently separated in the animal tree of evolution. 3. The possibility of a peculiar kinetic behaviour of the glycolytic pathway in each muscle tissue studied, has been analyzed as the profiles of the ratios of pairs of enzymes bearing a substrate-product dependence. 4. A possible "futile synthesis" of some glycolytic enzymes, such as FDP-aldolase in the case of fish muscle, is proposed.     

Seasonal changes in the activities of glycolytic enzymes from liver and skeletal muscle of Rana perezi

Glycogen phosphorylase (GP), Hexokinase (HK), Phosphofructokinase (PFK), Pyruvate kinase (PK) and Lactate dehydrogenase (LDH) activities from skeletal muscle and liver were measured in Rana perezi for the four seasons of the year. Skeletal muscle showed a decrease in PFK, PK and LDH activity during winter and summer. Liver displayed an increase in GP activity in spring and in PK and LDH in autumn.     

Seasonal variations in the activities of peroxide metabolism enzymes in erythrocytes of freshwater fish species

Superoxide dismutase, catalase and peroxidase activities were estimated in erythrocytes of the carp, the tench and the crucian carp. The enzymes showed higher activities in spring (1982) than in autumn (1981). In both seasons the highest levels of these antioxidative defense enzymes were found in erythrocytes of the crucian carp.     

Nearshore contagion and sampling of freshwater larval fish

The existence of larval fish contagion and its approximate magnitudein four different biotopes: at the shore of a river, surfaceand at fixed depth at an exposed coast of a large lake, andin a shallow, sheltered bay, was investigated, using passiveand active sampling. Non-random distributions were the rule;patchiness differed according to species, size, abundance anddiurnal movement, and was inversely related to distance fromshore. Characterization of contagion was hindered by samplingequipment and techniques, which were found wanting.     

Deep-sea mystery solved: astonishing larval transformations and extreme sexual dimorphism unite three fish families

The oceanic bathypelagic realm (1000–4000m) is a nutrient-poor habitat. Most fishes living there have pelagic larvae using the rich waters of the upper 200m. Morphological and behavioural specializations necessary to occupy such contrasting environments have resulted in remarkable developmental changes and life-history strategies. We resolve a long-standing biological and taxonomic conundrum by documenting the most extreme example of ontogenetic metamorphoses and sexual dimorphism in vertebrates. Based on morphology and mitogenomic sequence data, we show that fishes currently assigned to three families with greatly differing morphologies, Mirapinnidae (tapetails), Megalomycteridae (bignose fishes) and Cetomimidae (whalefishes), are larvae, males and females, respectively, of a single family Cetomimidae. Morphological transformations involve dramatic changes in the skeleton, most spectacularly in the head, and are correlated with distinctly different feeding mechanisms. Larvae have small, upturned mouths and gorge on copepods. Females have huge gapes with long, horizontal jaws and specialized gill arches allowing them to capture larger prey. Males cease feeding, lose their stomach and oesophagus, and apparently convert the energy from the bolus of copepods found in all transforming males to a massive liver that supports them throughout adult life.     

Proteasomal activities in the claw muscle tissue of European lobster, Homarus gammarus, during larval development

Decapod crustaceans grow discontinuously and gain size through complex molt processes. The molt comprises the loss of the old cuticle and, moreover, substantial reduction and re-organization of muscles and connective tissues. In adult lobsters, the muscle tissue of the massive claws undergoes significant atrophy of 40-75% before ecdysis. The degradation of this tissue is facilitated by calcium-dependent proteases and by the proteasome, an intra-cellular proteolytic multi-enzyme complex. In contrast to the adults, the involvement of the proteasome during the larval development is yet not validated. Therefore, we developed micro-methods to measure the 20S and the 26S proteasomal activities within mg- and sub-mg-quantities of the larval claw tissue of the European lobster, Homarus gammarus. Within the three larval stages (Z1-3) we distinguished between sub-stages of freshly molted/hatched (post-molt), inter-molt, and ready to molt (pre-molt) larvae. Juveniles were analyzed in the post-molt and in the inter-molt stage. The trypsin-like, the chymotrypsin-like, and the peptidyl-glutamyl peptide hydrolase activity (PGPH) of the 20S proteasome increased distinctly from freshly hatched larvae to pre-molt Z1. During the Z2 stage, the activities were highest in the post-molt animals, decreased in the inter-molt animals and increased again in the pre-molt animals. A similar but less distinct trend was evident in the Z3 stages. In the juveniles, the proteasomal activities decreased toward the lowest values. A similar pattern was present for the chymotrypsin-like activity of the 26S proteasome. The results show that the proteasome plays a significant role during the larval development of lobsters. This is not only reflected by the elevated activities, but also by the continuous change of the trypsin/chymotrypsin-ratio which may indicate a shift in the subunit composition of the proteasome and, thus, a biochemical adjustment to better cope with elevated protein turnover rates during larval development.     

Externalized glycolytic enzymes are novel, conserved, and early biomarkers of apoptosis

The intriguing cell biology of apoptotic cell death results in the externalization of numerous autoantigens on the apoptotic cell surface, including protein determinants for specific recognition, linked to immune responses. Apoptotic cells are recognized by phagocytes and trigger an active immunosuppressive response ("innate apoptotic immunity" (IAI)) even in the absence of engulfment. IAI is responsible for the lack of inflammation associated normally with the clearance of apoptotic cells; its failure also has been linked to inflammatory and autoimmune pathology, including systemic lupus erythematosus and rheumatic diseases. Apoptotic recognition determinants underlying IAI have yet to be identified definitively; we argue that these molecules are surface-exposed (during apoptotic cell death), ubiquitously expressed, protease-sensitive, evolutionarily conserved, and resident normally in viable cells (SUPER). Using independent and unbiased quantitative proteomic approaches to characterize apoptotic cell surface proteins and identify candidate SUPER determinants, we made the surprising discovery that components of the glycolytic pathway are enriched on the apoptotic cell surface. Our data demonstrate that glycolytic enzyme externalization is a common and early aspect of cell death in different cell types triggered to die with distinct suicidal stimuli. Exposed glycolytic enzyme molecules meet the criteria for IAI-associated SUPER determinants. In addition, our characterization of the apoptosis-specific externalization of glycolytic enzyme molecules may provide insight into the significance of previously reported cases of plasminogen binding to α-enolase on mammalian cells, as well as mechanisms by which commensal bacteria and pathogens maintain immune privilege.     

Copper-induced oxidative stress in Saccharomyces cerevisiae targets enzymes of the glycolytic pathway

Increased cellular levels of reactive oxygen species are known to arise during exposure of organisms to elevated metal concentrations, but the consequences for cells in the context of metal toxicity are poorly characterized. Using two-dimensional gel electrophoresis, combined with immunodetection of protein carbonyls, we report here that exposure of the yeast Saccharomyces cerevisiae to copper causes a marked increase in cellular protein carbonyl levels, indicative of oxidative protein damage. The response was time dependent, with total-protein oxidation peaking approximately 15 min after the onset of copper treatment. Moreover, this oxidative damage was not evenly distributed among the expressed proteins of the cell. Rather, in a similar manner to peroxide-induced oxidative stress, copper-dependent protein carbonylation appeared to target glycolytic pathway and related enzymes, as well as heat shock proteins. Oxidative targeting of these and other enzymes was isoform-specific and, in most cases, was also associated with a decline in the proteins' relative abundance. Our results are consistent with a model in which copper-induced oxidative stress disables the flow of carbon through the preferred glycolytic pathway, and promotes the production of glucose-equivalents within the pentose phosphate pathway. Such re-routing of the metabolic flux may serve as a rapid-response mechanism to help cells counter the damaging effects of copper-induced oxidative stress.     

Effect of hypoxia on phosphoesterases,oxidative and glycolytic enzymes in the rabbit common carotid artery

Summary An enzyme-histochemical study was performed on the rabbit common carotid artery at periods ranging from one to seventeen days following double-ligation and injections of human , human pre- serum lipoproteins and a physiologic saline into the lumen. The alterations in enzyme activities compared to the contralateral carotid (control) were studied for DPN diaphorase, succinic acid dehydrogenase (SDH), lactic acid dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G-6-pH DH), ATPase, AMPase, acid and alkaline phosphatase. At earlier time intervals there was a general reduction in oxidative enzyme and ATPase activities concomitant with a general increase in LDH and acid phosphatase activities. At later times oxidative enzyme and ATPase activities returned to their control levels and actually increased in the thickened intima. LDH and acid phosphatase activities remained above the control levels, especially in the thickened intima. Focal areas, presumably necrotic, demonstrated complete loss of activity for all enzymes studied. AMPase activity did not differ from the controls throughout this study, while G-6-pH DH and alkaline phosphatase activities were found only sparsely in the adventitia. The same general pattern of alteration in enzyme activity was found regardless of the substance injected into the ligated artery. Arguments for the use of this experimental model for studies on the pathogenesis of atherosclerosis are given.     

Development of the activities of enzymes of the isoprenoid pathway during early stages of pea-seed germination

The activities of individual enzymes of the isoprenoid pathway from mevalonate kinase to squalene synthetase in homogenates of seeds germinated up to 32h were assayed. Changes in the activity of each enzyme were observed and compared with the activity at the 2h germination stage. Activities of alkaline phosphatase and fructose 1,6-diphosphate aldolase were similarly measured to provide a reference for changes in the general metabolic activity of seeds during imbibition of water. Water uptake reached a plateau after 12h. The reference enzymes almost doubled in activity between 2 and 8h and thereafter their activities steadily declined. All of the enzymes of the isoprenoid pathway increased in activity between 2 and 6h and, thereafter, with the exception of the prenyltransferase, their activities remained relatively constant. With the prenyltransferase activity the initial increase was followed by a short plateau between 6 and 9h and then a second increase to a maximum between 14 and 16h. After 16h the activity declined. The relative activities of the isoprenoid enzymes at 16h of germination were mevalonate kinase>phosphomevalonate kinase>pyrophosphomevalonate decarboxylase≈isopentenyl pyrophosphate isomerase>squalene synthetase>isopentenyl pyrophosphate/dimethylallyl pyrophosphate prenyltransferase. The finding that the prenyltransferase may be the rate-limiting enzyme in squalene synthesis from mevalonate is discussed in relation to regulation of isoprenoid synthesis during pea-seed germination.     

The physiological responses of blood during thermal adaptation in three freshwater fish species

Sarotherodon mossambicus , Cyprinus carpio and Salmo gairdneri were acclimatized at temperatures of 15, 20 and 25° C in order to study physiological responses of blood to temperature fluctuations in the laboratory. Cyprinus carpio exhibited the greater ability to survive at these temperatures. Sarotherodon mossambicus experienced osmoregulatory collapse at 15° C which also occurred in trout at 25° C. This was associated with acid-base malfunction in the trout.     

Prenatal and early life arsenic exposure induced oxidative damage and altered activities and mRNA expressions of neurotransmitter metabolic enzymes in offspring rat brain

To better understand the effect of arsenic on central nervous system by prenatal and early life exposure, the oxidative stress and neurotransmitter metabolic enzymes were determined in offspring rats' brain cortex and hippocampus. Forty‐eight pregnant rats were randomly divided into four groups, each group was given free access to drinking water that contained 0, 10, 50, and 100 mg/L NaAsO₂ from gestation day 6 (GD 6) until postnatal day 42 (PND 42). Once pups were weaned, they started to drink the same arsenic (As)‐containing water as the dams. The level of malondialdehyde in 100 mg/L As‐exposed pup's brain on PND 0 and cortex on PND 28 and 42 were significantly higher than in the control group (p < 0.05). Reduced glutathione (GSH) levels showed a clear decreasing trend in pup's cortex and hippocampus on PND 42. Activity of acetylcholinesterase was significantly higher in 100 mg/L As‐exposed pup's hippocampus than in control group on PND 28 and 42. mRNA expression of glutamate decarboxylase (GAD₆₅ and GAD₆₇) in 100 mg/L As‐exposed pup's cortex or hippocampus on PND 28 and 42 were significantly higher than in control (p < 0.05). These alterations in the neurotransmitters and reduced antioxidant defence may lead to neurobehavioral and learning and memory changes in offspring rats. © 2010 Wiley Periodicals, Inc. J Biochem Mol Toxicol 24:368–378, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/jbt.20349     

Comparative activities of glycolytic enzymes in yeast and mycelial forms of Candida albicans

Through use of a synthetic defined medium which allows for the exclusive growth of yeast or mycelial forms of Candida albicans the activity of several major glycolytic enzymes in these forms were examined and compared. The results indicate vast metabolic differences between the forms. These data are discussed in relationship to the phenomenon of morphogenesis in C. albicans which in turn relates to problems in immunology and pathogenics of this important opportunistic organism.