CHANGES IN LIPOLYSIS AND LIPOGENESIS IN SELECTED TISSUES OF THE LANDLOCKED LAMPREY, PETROMYZON-MARINUS, DURING METAMORPHOSIS

This study was designed to examine the biochemical basis of lipid alte rations in liver, kidney, and intestine of sea lamprey, Petromyzon mar inus, during their nontrophic metamorphosis. Lipolysis, as indicated b y triacylglycerol lipase (TGL) activity, increased in liver from larva to stage 6 and in kidney from stage 3 to stage 5, but declined in int estine from stage 3 to stage 5. Fatty acid synthesis and triacylglycer ol synthesis were assessed by acetyl-CoA carboxylase (ACC) and diacylg lycerol acyltransferase (DCTAT) activities, respectively. Acetyl-CoA c arboxylase activity decreased in kidney from larva to stage 6 and in l iver from stage 3 to stage 6. Diacylglycerol acyltransferase activity in liver increased from larva to stage 5 and in intestine from stage 3 to stage 6, but it was unchanged in kidney. Oxidative metabolism, as estimated by citrate synthase (CS) activity, decreased in liver and in testine from larva to stage 6 and in kidney from larva to stage 3. The se data indicate that changes in the activities of TGL, ACC, DGAT, and CS are development-dependent and tissue-specific and suggest that lam prey metamorphosis proceeds in two distinct metabolic phases. The firs t phase, displayed in larva and stage 3 of metamorphosis, is predomina ted by lipid depletion from intestine and lipid accumulation in liver and kidney, whereas the second phase, displayed in stage 3 to stage 6, is predominated by lipid depletion from liver and kidney and lipid ac cumulation in intestine. These biochemical changes may provide the ene rgy required for the pronounced developmental reorganization that occu rs during nontrophic metamorphosis of lamprey. (C) 1997 Wiley-Liss, In c.