Enzyme activities in the Atlantic hagfish, Myxine glutinosa: changes with captivity and food deprivation

1986 ◽  
Vol 64 (5) ◽  
pp. 1080-1085 ◽  
Author(s):  
Glen D. Foster ◽  
T. W. Moon
Keyword(s):  
Food Deprivation ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Citrate Synthase ◽  
Krebs Cycle ◽  
Metabolic Potential ◽  
Metabolizing Enzymes ◽  
Myxine Glutinosa ◽  
Hydroxyacyl Coa Dehydrogenase ◽  
Krebs Cycle Enzymes ◽  
Glucose 6 Phosphate Dehydrogenase

Selected Krebs cycle enzymes and carbohydrate, amino acid, and lipid metabolizing enzymes were assayed in the muscle and liver of newly captured (April, 4 °C; August, 15 °C), fed (for 7 months), and food-deprived (for 7 and 11 months) hagfish, Myxine glutinosa. Seasonal differences were found in the glycogen content of the muscle and liver of newly captured hagfish (lower in the cold temperature), while consistently high levels were maintained in the fed group. Food deprivation decreased the content. All enzymes measured were found in both tissues, except glucose-6-phosphate dehydrogenase (liver only) and glycerol kinase (absent in both tissues). Activities of the enzymes were lower than teleost values, except for pyruvate kinase, citrate synthase, and 3-hydroxyacyl-CoA dehydrogenase, for which activities resembled teleost levels. Enzyme values from the fed fish (7 months) were generally the same as the newly captured group, and food deprivation increased phosphoenolpyruvate carboxykinase activities without altering other enzyme levels. These results support the view that hagfish are anoxia tolerant with low metabolic potential and demonstrate that the muscle and liver rely on carbohydrate and lipid reserves during fasting.

Comparison of glycolytic, pentose phosphate pathway, glyoxylate shunt, Krebs' cycle enzymes in Ganeo tigrinum parasitizing hibernating and non-hibernating Rana cyanophlyctis and R. tigrina

1983 ◽  
Vol 57 (1) ◽  
pp. 59-68 ◽  
Author(s):  
P. N. Sharma ◽  
Sushila Mandawat
Keyword(s):  
Isocitrate Lyase ◽  
Krebs Cycle ◽  
Pentose Phosphate ◽  
Glyoxylate Shunt ◽  
Strong Activity ◽  
Key Enzymes ◽  
Phosphogluconate Dehydrogenase ◽  
Weak Activity ◽  
Krebs Cycle Enzymes ◽  
Glucose 6 Phosphate Dehydrogenase

AbstractThe histochemical site and distribution of hexokinase, glycogen phosphorylase (GP Rylase), lactate dehydrogenase (LDH) (key enzymes of glycolysis), glucose-6-phosphate dehydrogenase (GPD) and 6-phosphogluconate dehydrogenase (6PGD) (pentose phosphate shunt enzymes), isocitrate dehydrogenase (IDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), and α-ketoglutarate dehydrogenase (α-KDH) (key enzymes of Krebs' cycle), malate synthetase (MS) and isocitrate lyase (IL) (enzymes of glyoxylate shunt) in various tissues of Ganeo tigrinum from hibernating and non-hibernating Rana cyanophlyctis and R. tigrina were studied. Differences in their intensities were revealed. Weak activity of GP Rylase and strong activity of hexokinase in flukes from non-hibernating hosts indicates that they utilize glucose through glycolysis for energy turnover. Intense GP Rylase and weak hexokinase activity in worms from hibernating hosts indicates the utilization of glycogen. Strong activity of IDH, SDH, MDH, α-KGD, MS and IL was demonstrable in the tissues of flukes from non-hibernating hosts, suggesting that Krebs' cycle and glyoxylate shunt, respectively, were operating. Tissues of the fluke from hibernating hosts, on the other hand, displayed positive activity only for SDH and MDH; no activity for MS and IL, the enzymes of glyoxylate shunt, was observed, The activity of the above enzymes was found to be relatively low in worms from hibernating hosts.

Posttranslational modifications and dysfunction of mitochondrial enzymes in human heart failure

2016 ◽  
Vol 311 (2) ◽  
pp. E449-E460 ◽  
Author(s):  
Freya L. Sheeran ◽  
Salvatore Pepe
Keyword(s):  
Heart Failure ◽  
Citrate Synthase ◽  
Krebs Cycle ◽  
Left Ventricular ◽  
Oxidative Modification ◽  
Left Ventricular Myocardium ◽  
Mitochondrial Enzymes ◽  
Altered Expression ◽  
Krebs Cycle Enzymes ◽  
End Stage

Deficiency of energy supply is a major complication contributing to the syndrome of heart failure (HF). Because the concurrent activity profile of mitochondrial bioenergetic enzymes has not been studied collectively in human HF, our aim was to examine the mitochondrial enzyme defects in left ventricular myocardium obtained from explanted end-stage failing hearts. Compared with nonfailing donor hearts, activity rates of complexes I and IV and the Krebs cycle enzymes isocitrate dehydrogenase, malate dehydrogenase, and aconitase were lower in HF, as determined spectrophotometrically. However, activity rates of complexes II and III and citrate synthase did not differ significantly between the two groups. Protein expression, determined by Western blotting, did not differ between the groups, implying posttranslational perturbation. In the face of diminished total glutathione and coenzyme Q10levels, oxidative modification was explored as an underlying cause of enzyme dysfunction. Of the three oxidative modifications measured, protein carbonylation was increased significantly by 31% in HF ( P < 0.01; n = 18), whereas levels of 4-hydroxynonenal and protein nitration, although elevated, did not differ. Isolation of complexes I and IV and F1FoATP synthase by immunocapture revealed that proteins containing iron-sulphur or heme redox centers were targets of oxidative modification. Energy deficiency in end-stage failing human left ventricle involves impaired activity of key electron transport chain and Krebs cycle enzymes without altered expression of protein levels. Augmented oxidative modification of crucial enzyme subunit structures implicates dysfunction due to diminished capacity for management of mitochondrial reactive oxygen species, thus contributing further to reduced bioenergetics in human HF.

Effects of insulin, glucocorticoids and thyroid hormones on the activities of key enzymes of glycolysis, glutaminolysis, the pentose-phosphate pathway and the Krebs cycle in rat macrophages

1992 ◽  
Vol 135 (2) ◽  
pp. 213-219 ◽  
Author(s):  
L. F. B. P. Costa Rosa ◽  
Y. Cury ◽  
R. Curi
Keyword(s):  
Thyroid Hormones ◽  
Pentose Phosphate Pathway ◽  
Culture Medium ◽  
Citrate Synthase ◽  
Inflammatory Responses ◽  
Krebs Cycle ◽  
Pentose Phosphate ◽  
Macrophage Phagocytosis ◽  
And Function ◽  
Glucose 6 Phosphate Dehydrogenase

ABSTRACT In the present study the effects of insulin, glucocorticoids and thyroid hormones on macrophage metabolism and function were investigated. The maximum activities of hexokinase, glucose-6-phosphate dehydrogenase, glutaminase and citrate synthase were determined in macrophages obtained from hormonetreated rats and those cultured for a period of 48 h in the presence of hormones. Macrophage phagocytosis was markedly inhibited by dexamethasone and thyroid hormones, remaining unchanged when insulin was added to the culture medium, however. The changes in the enzyme activities caused by hormone treatments of the rats were very similar to those found in culture. Insulin enhanced citrate synthase and hexokinase activities and diminished those of glutaminase and glucose-6-phosphate dehydrogenase. Dexamethasone had a similar effect except on glucose6-phosphate dehydrogenase. The addition of thyroid hormones to the culture medium raised the activities of glutaminase and hexokinase and reduced that of citrate synthase. The results presented support the suggestion that the effects of insulin, glucocorticoids and thyroid hormones on immune and inflammatory responses could well be mediated through changes in macrophage metabolism.. Journal of Endocrinology (1992) 135, 213–219

An Attempt at the Cytochemical Localization of Citrate Synthase in Rat Heart Muscle

1976 ◽  
Vol 34 ◽  
pp. 86-87 ◽  
Author(s):  
M. A. Matlib ◽  
W. A. Shannon ◽  
P. A. Srere
Keyword(s):  
Heart Muscle ◽  
Rat Heart ◽  
Citrate Synthase ◽  
Krebs Cycle ◽  
Model Systems ◽  
Soluble Form ◽  
Cytochemical Localization ◽  
Inner Membrane ◽  
Membrane Area ◽  
Krebs Cycle Enzymes

Most of the Krebs cycle enzymes are believed to exist in ‘soluble’ form in the mitochondrial matrix except succinate dehydrogenase which is a part of the inner membrane (1). Citrate synthase, one of the Krebs cycle enzymes, is present in rat liver, kidney and heart mitochondria proportional to the amount of the inner membrane area rather than the matrix volume (2). Recent studies on model systems support the idea that the ‘soluble’ Krebs cycle enzymes are probably localized on the inner surface (matrix side) of the inner membrane (3-5). Localization of these enzymes in mitochondria by cytochemical or immunocytochemical methods would be crucial to determine the validity of the above hypothesis. The present study describes cytochemical localization of citrate synthase in rat heart muscle.

scholarly journals The impact of obesity, sex, and diet on hepatic glucose production in cats

2009 ◽  
Vol 296 (4) ◽  
pp. R936-R943 ◽  
Author(s):  
Saskia Kley ◽  
Margarethe Hoenig ◽  
John Glushka ◽  
Eunsook S. Jin ◽  
Shawn C. Burgess ◽  
...  
Keyword(s):  
Phosphoenolpyruvate Carboxykinase ◽  
Citrate Synthase ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Endogenous Glucose Production ◽  
Hepatic Glucose Metabolism ◽  
Peripheral Insulin Resistance ◽  
Pyruvate Cycling ◽  
Hepatic Glucose ◽  
The Impact

Obesity is a risk factor for type 2 diabetes in cats. The risk of developing diabetes is severalfold greater for male cats than for females, even after having been neutered early in life. The purpose of this study was to investigate the role of different metabolic pathways in the regulation of endogenous glucose production (EGP) during the fasted state considering these risk factors. A triple tracer protocol using 2H2O, [U-13C3]propionate, and [3,4-13C2]glucose was applied in overnight-fasted cats (12 lean and 12 obese; equal sex distribution) fed three different diets. Compared with lean cats, obese cats had higher insulin ( P < 0.001) but similar blood glucose concentrations. EGP was lower in obese cats ( P < 0.001) due to lower glycogenolysis and gluconeogenesis (GNG; P < 0.03). Insulin, body mass index, and girth correlated negatively with EGP ( P < 0.003). Female obese cats had ∼1.5 times higher fluxes through phosphoenolpyruvate carboxykinase ( P < 0.02) and citrate synthase ( P < 0.05) than male obese cats. However, GNG was not higher because pyruvate cycling was increased 1.5-fold ( P < 0.03). These results support the notion that fasted obese cats have lower hepatic EGP compared with lean cats and are still capable of maintaining fasting euglycemia, despite the well-documented existence of peripheral insulin resistance in obese cats. Our data further suggest that sex-related differences exist in the regulation of hepatic glucose metabolism in obese cats, suggesting that pyruvate cycling acts as a controlling mechanism to modulate EGP. Increased pyruvate cycling could therefore be an important factor in modulating the diabetes risk in female cats.

Influence of training on skeletal muscle enzymatic adaptations in normal and diabetic rats

1985 ◽  
Vol 249 (4) ◽  
pp. E360-E365 ◽  
Author(s):  
E. G. Noble ◽  
C. D. Ianuzzo
Keyword(s):  
Skeletal Muscle ◽  
Exercise Training ◽  
Citrate Synthase ◽  
Diabetic Rats ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Marker Enzymes ◽  
Oxidative Potential ◽  
Hydroxyacyl Coa Dehydrogenase ◽  
Fast Twitch

Muscle homogenates representing slow-twitch oxidative, fast-twitch oxidative-glycolytic, fast-twitch glycolytic, and mixed fiber types were prepared from normal, diabetic, and insulin-treated diabetic rats. Diabetes was induced by injection of 80 mg . kg-1 of streptozotocin. The activities of citrate synthase, succinate dehydrogenase, and 3-hydroxyacyl-CoA dehydrogenase were employed as markers of oxidative potential, whereas phosphorylase, hexokinase, and phosphofructokinase activities were used as an indication of glycolytic capacity. Diabetes was associated with a general decrement in the activity of oxidative marker enzymes for all fiber types except the fast-twitch glycolytic fiber. In contrast, the fast-twitch glycolytic fibers demonstrated the greatest decline in glycolytic enzymatic activity. Insulin-treated animals, either trained or untrained, exhibited enzyme activities similar to their normal counterparts. Exercise training of diabetic rats mimicked the effect of insulin treatment and caused a near normalization of the activity of the marker enzymes. These findings suggest that the enzymatic potential of all skeletal muscle fiber types of diabetic rats may be normalized by exercise training even in the absence of significant amounts of insulin.

Size Scaling of Whole-Body Maximal Enzyme Activities in Aquatic Crustaceans

1991 ◽  
Vol 48 (12) ◽  
pp. 2385-2394 ◽  
Author(s):  
Jonn A. Berges ◽  
James S. Ballantyne
Keyword(s):  
Life History ◽  
Enzyme Activities ◽  
Citrate Synthase ◽  
Macrobrachium Rosenbergii ◽  
Nucleoside Diphosphate Kinase ◽  
Whole Body ◽  
Allometric Relationship ◽  
Scaling Exponents ◽  
Interspecific Differences ◽  
Glucose 6 Phosphate Dehydrogenase

The relationships between body size and maximal activities of eight enzymes were measured in whole-body homogenates of the crustaceans Macrobrachium rosenbergii, Artemia franciscana, and Daphnia magna. Interspecifically and intraspecificaily, enzyme activities per animal (Y) scale with protein weight (W) according to the allometric relationship Y = aWb. Scaling exponents (b) varied with the enzyme examined and were usually different from 0.75. For enzymes such as citrate synthase, intraspecific and interspecific exponents were similar, but for enzymes associated with pathways other than aerobic metabolism, significant differences were found between species. For anaerobic enzymes such as lactate dehydrogenase, these differences may relate to interspecific differences in life history and ecology. For anabolic enzymes such as glucose-6-phosphate dehydrogenase and nucleoside diphosphate kinase, differences may relate to differences in growth rates between species.

scholarly journals Diffuse Gliomas for Nonneuropathologists: The New Integrated Molecular Diagnostics

2018 ◽  
Vol 142 (7) ◽  
pp. 804-814 ◽  
Author(s):  
Sunhee C. Lee
Keyword(s):  
Krebs Cycle ◽  
Diagnostic Algorithm ◽  
World Health ◽  
Wild Type ◽  
Targeted Next Generation Sequencing ◽  
Idh Mutations ◽  
Diffuse Gliomas ◽  
Conventional Histology ◽  
Krebs Cycle Enzymes ◽  
Health Organization

Diffuse gliomas comprise the bulk of “brain cancer” in adults. The recent update to the 4th edition of the World Health Organization's classification of tumors of the central nervous system reflects an unprecedented change in the landscape of the diagnosis and management of diffuse gliomas that will affect all those involved in the management and care of patients. Of the recently discovered gene alterations, mutations in the Krebs cycle enzymes isocitrate dehydrogenases (IDHs) 1 and 2 have fundamentally changed the way the gliomas are understood and classified. Incorporating information on a few genetic parameters (IDH, ATRX and/or p53, and chromosome 1p19q codeletion), a relatively straightforward diagnostic algorithm has been generated with robust and reproducible results that correlate with patients' survival far better than relying on conventional histology alone. Evidence also supports the conclusion that the vast majority of diffuse gliomas without IDH mutations (IDH–wild-type astrocytomas) behave like IDH–wild-type glioblastomas (“molecular GBM”). Together, these changes reflect a big shift in the practice of diagnostic neuropathology in which tumor risk stratification aligns better with molecular information than histology/grading. The purpose of this review is to provide the readers with a brief synopsis of the changes in the 2016 World Health Organization update with an emphasis on diffuse gliomas and to summarize key gene abnormalities on which these classifications are based. Practical points involved in day-to-day diagnostic workup are also discussed, along with a comparison of the various diagnostic tests, including immunohistochemistry, with an emphasis on targeted next-generation sequencing panel technology as a future universal approach.

Biochemical correlates of flying behaviour in bats

1978 ◽  
Vol 26 (1) ◽  
pp. 29 ◽  
Author(s):  
BD Muller ◽  
J Baldwin
Keyword(s):  
Lactate Dehydrogenase ◽  
Functional Properties ◽  
Krebs Cycle ◽  
Pectoral Muscle ◽  
Anaerobic Glycolysis ◽  
Krebs Cycle Enzymes ◽  
Lactate Dehydrogenase Isoenzymes

The activities of glycolytic and Krebs cycle enzymes, and the distribution and functional properties of lactate dehydrogenase isoenzymes, were determined in pectoral muscles from a range of bats that differ in flying behaviour. Correlations were found between flying patterns, and the degree to which the pectoral muscle depended upon anaerobic glycolysis during fight.

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