BIOCHEMICAL PHASES IN EMBRYONIC RED-SEA BREAM DEVELOPMENT

Changes in chemical constituents and enzyme activities were assayed in red sea bream Pagrus major through embryonic development from eggs im mediately after fertilization to larvae just before feeding. No signif icant changes were found in protein, total nitrogen, and phospholipid contents with proceeding development stages. Although free amino acid (FAA) and triacylglycerol (TAG) contents continuously fell, DNA and RN A contents reversely increased through the development. Ammonia, free glucose, and glycogen contents were maintained at markedly low levels. Aspartate aminotransferase, alanine aminotransferase, creatine kinase , and alkaline phosphatase activities showed a similar change through the development, decreasing or remaining constant at low levels up to the stage of Kupffer's vesicle appearance and increasing steeply there after. These results suggest that endogenous TAG and FAA are preferent ially expended as energy reserves under the embryonic development of r ed sea bream. The rapid increases of the enzyme activities after the s tage of Kupffer's vesicle appearance might correspond to their organ d ifferentiation and function.