Modulation of Carbohydrate Metabolism in Asiatic Rhinoceros Beetle (Oryctes rhinoceros [L]) Grubs in Response to Various Stressors
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Hemolymph of healthy grubs of Oryctes rhinoceros possesses trehalose content of 380 ± 30 mg/dl that is five times higher than the content of glucose. Experimental stressors, either internal or external have resulted in the elevation of glucose through degradation of trehalose mediated by the elevated activity of trehalase; the hyperglycaemia was disproportionate with the decrease of trehalose content. Glycogen phosphorylase (GP), an important enzyme of the skeletal muscle of vertebrates was located in the cell free hemolymph of grubs, at an exponentially elevated level of 320 ± 20 µmols/min/mg protein. Both GP and Hexokinase showed a sharp reduction in activity under exposure to stressors. Accumulation of lactic acid along with an increase in lactate dehydrogenase activity was observed. Inhibition of GP activity by hyperglycaemia together with decline of hexokinase and glyceraldehyde-3-phosphate dehydrogenase, proves that the larvae might have adopted an energy conserving mechanism and thereby channelling glucose for the purpose of defense. Elevation of glucose-6-phosphatase and glucose-6-phosphate dehydrogenase during stress may also help them to synthesis defensive chemicals like glutathione and polyols. Existence of such a wonderful biochemical mechanism helps them to thrive very well in cow dung pits a microenvironment possessing biotic and abiotic stressors, without undergoing diapause.
KeywordsGlucose Pentose pathway Lactate dehydrogenase Hexokinase Glucose-6-phosphatase Glucose-6-phosphate dehydrogenase
The authors are grateful to the University of Kerala for the Ph. D. research fellowship provided for the successful completion of the work as well as to the Faculty and colleagues at the Department of Zoology of University College and NSS College, Pandalam for the facilities provided, support and help. The author alone is responsible for the content and writing of the paper. This study is part of the doctoral work and the whole work was approved by the ethical norms of the institution.
Compliance with Ethical Standards
Conflict of interest
Both authors of this research paper declare that they have no conflict of interest to publish this manuscript.
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