Differential biosynthesis of molecular species of 1,2-diacyl-sn-glycerols and phosphatidylcholines in cold and warm acclimated goldfish (Carassius auratus L.).

The initial incorporation of glycerol-3H into the molecular species of liver 1,2-diacyl-sn-glycerols and phosphatidylcholines was studied in vivo using goldfish acclimated to 10 C and 30 C. A 1.5- and 2.2-fold higher proportion of the total radioactivity in the diacylglycerols from cold acclimated fish was found to be associated with the trienoic and pentaenoic species, respectively, when compared to warm acclimated fish. In the phosphatidylcholines, 1.9- and 1.3-fold greater percentages of the newly-incorporated radioactivity were found in tetraenoic and pentaenoic molecules, respectively, from cold relative to warm acclimated fish which suggests a preferential synthesis of these molecules relative to other molecular species in response to a lowering of environmental temperature. The present results indicate, therefore, that environmental temperature influences the complement of molecular species of diacylglycerols an phosphatidylcholines which fish produce by way of de novo biosynthesis in vivo.