CHANGES IN CARBOHYDRATE-METABOLISM RELATED TO THE ONSET OF OVARIAN RECRUDESCENCE IN DOMESTICATED RAINBOW-TROUT (ONCORHYNCHUS-MYKISS)

1. A study of several carbohydrate metabolism pathways was carried out in three different tissues-liver, gonad and kidney-from domesticated female rainbow trout (Oncorhynchus mykiss) at three different stages o f gonadal maturation, i.e. previtellogenesis, endogenous vitellogenesi s and the onset of exogenous vitellogenesis. 2. A fall in liver glycog en levels was observed at the beginning of gonadal recrudescence. The glucose obtained by glycogen rupture appears to be used both in liver glycolysis and in generating reducing power. In addition, a decrease i n both the use of exogenous glucose and gluconeogenesis was also obser ved. 3. A large increase in gonad glucose levels was observed at the b eginning of gonadal recrudescence. This increase may be due to both a higher use of exogenous glucose (from diet and other tissues) and an i ncreased gluconeogenesis. The higher glucose levels appear to be used not only in glycogen synthesis, but also in producing reducing power. 4. No changes were observed in kidney metabolism that could be related to the initial stages of gonadal maturation. 5. The onset of the gona dal recrudescence in female rainbow trout is mainly associated with a higher use of glucose in the gonad and increased metabolic activity in the liver.