Biochemical differences in lateral muscle of wild and farmed gilthead sea bream (Sparus aurata L.)

Red and white muscle from specimens of wild and farmed gilthead sea bream ( Sparus aurata) were analyzed for histochemical ATPase activity, total prote in content, fatty acids, trace element concentrations and myosin isoforms. The fibre type composition of muscle samples was confirmed histochemically by the ATPase reaction, which did not show any differences between the two groups of animals. Myosin ATPase activities, myosin and protein yields were significantly higher in white muscle than in the red muscle and for the re d muscle the latter two parameters were higher in wild fish. Fatty acid pro files revealed differences between the two groups of animals, probably beca use of the fatty acid composition of the diets. Zinc, copper and iron conce ntrations were higher in red muscle than in white muscle; muscles from wild fish were significantly richer in trace elements. No separation of fast an d slow heavy chains of myosin could be obtained on SDS-gel electrophoresis, but two dimensional electrophoresis revealed the presence of three light c hains in white muscle (LC1F, LC2F, LC3F), and two main types in red muscle (LC1S, LC2S). Small, variable percentages of LC3F were found in the red mus cle samples, especially in the wild fish. It is concluded that the differen t environmental conditions, experienced by wild and farmed fish, have signi ficantly influenced the biochemical composition of their lateral muscle.