Alpha-Glycerol phosphatase and glycerol kinase activities in tissues of the silkmoth Hyalophora cecropia during the larval-pupal transformation.
Magnesium metabolism has been studied in Hyalophora cecropia during the larval-pupal transformation (LPT) (Jungreis, A. M., Am. J. Physiol. 224: 27--30, 1973). Throughout this period, it accumulated in midgut (0.5 M at ecdysis), presumably as osmotically inactive Mg3(PO4)2. Glycerol accumulation in hemolymph was also first noted during this period. Since total alpha-glycerol phosphate present in hemolymph declined between the larval and pupal stages of development, the relationship between magnesium and alpha-glycerol phosphate metabolism was studied. Specific and total alpha-glycerol phosphatase (degradative) and glycerol kinase (synthetic) enzyme activities were measured in fat-body and midgut tissue throughout the LPT. At both feeding larval and diapause pupal stages in development in both tissues, total glycerol kinase activity is greater than that of alpha-glycerol phosphatase with degradative/synthetic activity ratios of 0.2--0.5. In fat body, ratios remained constant or shifted in the direction of synthesis during the LPT, whereas those measured in midgut tissue increased in the direction of degradation with a maximum ratio of 5.8 noted following spinning. The increase in degradative/synthetic activity ratios in midgut tissue is attributed to a greater rate of loss of glycerol kinase than alpha-glycerol phosphatase enzyme activity. Orthophosphate, presumably released from alpha-glycerol phosphate within the cells of the pharate pupal midgut tissue, combines with magnesium to form osmotically inactive Mg3(PO4)2 crystals.
D000818:Animals; D005990:Glycerol; D005991:Glycerol Kinase / Q000378:metabolism*; D007814:Larva; D007915:Lepidoptera / Q000502:physiology*; D008274:Magnesium / Q000378:metabolism; D008675:Metamorphosis, Biological; D009036:Moths / Q000378:metabolism / Q000502:physiology*; D010710:Phosphates / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010770:Phosphotransferases / Q000378:metabolism*; D011679:Pupa
D010710:Phosphates; D010770:Phosphotransferases; D005991:Glycerol Kinase; D010744:Phosphoric Monoester Hydrolases; D008274:Magnesium; D005990:Glycerol