Enzyme activity profiles in an overwintering population of freeze-avoiding gall moth larvae, Epiblema scudderiana

1994 ◽  
Vol 72 (6) ◽  
pp. 1079-1086 ◽  
Author(s):  
Denis R. Joanisse ◽  
Kenneth B. Storey
Keyword(s):  
Enzyme Activity ◽  
Winter Season ◽  
Late Winter ◽  
Hexose Monophosphate ◽  
Hexose Monophosphate Shunt ◽  
Epiblema Scudderiana ◽  
Polyol Dehydrogenase ◽  
Cryoprotectant Synthesis ◽  
Glycerol Synthesis ◽  
Glycerol 3 Phosphate Dehydrogenase

The maximal activities of enzymes of intermediary metabolism, notably glycolysis, the hexose monophosphate shunt, and polyol cryoprotectant synthesis were measured over a winter season in freeze-avoiding larvae of the gall moth Epiblema scudderiana. Dynamic changes in enzyme activities were found to reflect metabolic events associated with different and changing requirements of the larvae for survival as winter progressed and ended. Activities of enzymes associated with the cryoprotectant glycerol indicated two possible pathways for its synthesis: (1) glyceraldehyde-phosphate → glyceraldehyde → glycerol via glyceraldehyde phosphatase and NADPH-linked polyol dehydrogenase, or (2) dihydroxyacetonephosphate → glycerol-3-phosphate → glycerol via glycerol-3-phosphate dehydrogenase and glycerol-3-phosphatase. Glycogen phosphorylase activation in the fall supplied carbon equivalents required for glycerol synthesis from glycogen. Hexose monophosphate shunt enzyme activity was high, reflecting the role of this pathway in supplying NAD(P)H for glycerol synthesis. Spring clearance of glycerol appeared to occur via polyol dehydrogenase and glyceraldehyde kinase. Increasing fructose-bisphosphatase activity into late winter and spring was found to increase the gluconeogenic potential needed for cryoprotectant removal. Increased activity of glycerol-3-phosphate dehydrogenase in the spring, possibly reflecting increased α-glycero-phosphate shuttle activity, may be key to the removal of reducing equivalents generated from glycerol removal.

scholarly journals The effect of starvation and starvation followed by feeding on enzyme activity and the metabolism of [U−14C]glucose in liver from growing chicks

1968 ◽  
Vol 108 (4) ◽  
pp. 667-673 ◽  
Author(s):  
Alan G. Goodridge
Keyword(s):  
Fatty Acids ◽  
Enzyme Activity ◽  
Fatty Acid ◽  
Isocitrate Dehydrogenase ◽  
Malic Enzyme ◽  
Acid Synthesis ◽  
Minor Role ◽  
Hexose Monophosphate ◽  
Hexose Monophosphate Shunt ◽  
Cleavage Enzyme

1. The conversion of [U−14C]glucose into carbon dioxide, cholesterol and fatty acids in liver slices and the activities of ‘malic’ enzyme, citrate-cleavage enzyme, NADP-linked isocitrate dehydrogenase and hexose monophosphate-shunt dehydrogenases in the soluble fraction of homogenates of liver were measured in chicks that were starved or starved then fed. 2. In newly hatched chicks the incorporation of [U−14C]glucose and the activity of ‘malic’ enzyme did not increase unless the birds were fed. The response to feeding of [U−14C]glucose incorporation into fatty acids increased as the starved chicks grew older. 3. Citrate-cleavage enzyme activity increased slowly even when the newly hatched chicks were unfed. On feeding, citrate-cleavage enzyme activity increased at a much faster rate. 4. In normally fed 20-day-old chicks starvation decreased the incorporation of [U−14C]glucose into all three end products and depressed the activities of ‘malic’ enzyme and citrate-cleavage enzyme. Re-feeding increased all of these processes to normal or higher-than-normal levels. 5. In both newly hatched and 20-day-old chicks starvation increased the activity of isocitrate dehydrogenase and feeding or re-feeding decreased it. 6. Very little change in hexose monophosphate-shunt dehydrogenase activity was observed during the dietary manipulations. 7. The results indicate that increased substrate delivery to the liver is the principal stimulus to the increased rate of glucose metabolism observed in newly hatched chicks. The results also suggest that changes in the activities of ‘malic’ enzyme and citrate-cleavage enzyme are secondary to an increased flow of metabolites through the glucose-to-fatty acid pathway and that the dehydrogenases of the hexose monophosphate shunt play a minor role in NADPH production for fatty acid synthesis.

Cytoplasmic pH regulation in phorbol ester-activated human neutrophils

1986 ◽  
Vol 251 (1) ◽  
pp. C55-C65 ◽  
Author(s):  
S. Grinstein ◽  
W. Furuya
Keyword(s):  
Metabolic Pathways ◽  
Phorbol Esters ◽  
Ph Regulation ◽  
Human Neutrophils ◽  
Hexose Monophosphate ◽  
Cytoplasmic Ph ◽  
Extracellular Acidification ◽  
Hexose Monophosphate Shunt ◽  
Activated Neutrophils ◽  
Cytoplasmic Acidification

Activation of neutrophils by 12-O-tetradecanoylphorbol-13-acetate (TPA) is accompanied by an initial cytoplasmic acidification, followed by an alkalinizing phase due to Na+-H+ countertransport. The source of the acidification, which is fully expressed by activation with TPA in Na+-free or amiloride-containing media, was investigated. The acidification phase was detected also in degranulated and enucleated cytoplasts, ruling out a major contribution by the nucleus or secretory vesicles. Cytoplasmic acidification was found to be associated with an extracellular acidification, suggesting metabolic generation of H+. Two principal metabolic pathways are stimulated in activated neutrophils: the reduction of O2 by NADPH-oxidase and the hexose monophosphate shunt. A good correlation was found between the activity of these pathways and the changes in cytoplasmic pH. Inhibition of superoxide synthesis prevented the TPA-induced cytoplasmic acidification. Moreover, activation of the hexose monophosphate shunt with permeable NADPH-oxidizing agents (in the absence of TPA) also produced a cytoplasmic acidification. Cytoplasmic acidification was also elicited by exogenous diacylglycerol and by other beta-phorbol diesters, which are activators of the kinase, but not by unesterified phorbol or by alpha-phorbol diesters, which are biologically inactive. The results suggest that the cytoplasmic acidification induced by phorbol esters in neutrophils reflects accumulation of H+ liberated during the metabolic burst that follows activation.

scholarly journals Macrophage variants in oxygen metabolism.

1980 ◽  
Vol 152 (4) ◽  
pp. 808-822 ◽  
Author(s):  
G Damiani ◽  
C Kiyotaki ◽  
W Soeller ◽  
M Sasada ◽  
J Peisach ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Cytochrome C ◽  
Superoxide Anion ◽  
Oxygen Metabolism ◽  
Hexose Monophosphate ◽  
Phagocytic Cells ◽  
Form Complex ◽  
Hexose Monophosphate Shunt ◽  
Cytochrome C Reduction ◽  
Generate Superoxide Anion

Whereas phagocytic cells from normal individuals have the capacity to kill ingested bacteria and parasites, those from patients with several uncommon genetic deficiency diseases are known to be defective in bactericidal activity. Studies on neutrophils of these patients have revealed fundamental defects in their ability to reduce molecular oxygen and metabolize it to superoxide anion, hydrogen peroxide, and oxygen radicals. In the present experiments, we describe a clone of a continuous murine macrophage-like cell line, J774.16, that, upon appropriate stimulation, activates the hexose monophosphate shunt, and produces superoxide anion and hydrogen peroxide. With nitroblue tetrazolium to select against cells capable of being stimulated by phorbol myristate acetate to reduce the dye to polymer--formazan--which is toxic fot cells, we have selected for variants that are defective in oxygen metabolism. Four of these subclones have been characterized and found to be lacking in the ability (a) to generate superoxide anion, as measured by cytochrome c reduction; (b) to produce hydrogen peroxide, as measured by the ability to form complex I with cytochrome c peroxidase; and (c) to be stimulated to oxidize glucose via the hexose monophosphate shunt. These variants appear to represent a useful model for studying the molecular basis for macrophage cytocidal activity.

Activities of selected antioxidative, hydrolytic and hexose monophosphate shunt enzymes of skeletal muscle in neuromuscular diseases

2009 ◽  
Vol 69 (S98) ◽  
pp. 176-177
Author(s):  
V. V. Myllylä ◽  
T. E. S. Takala ◽  
U. Tolonen ◽  
A. Salminen ◽  
M. Kihlström ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Neuromuscular Diseases ◽  
Hexose Monophosphate ◽  
Hexose Monophosphate Shunt
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