Key fatty acids to develop healthy fish
VLC-PUFAs play a key role in many metabolic and physiological processes in vertebrates They are necessary for normal development by ensuring the proper functioning of the retina and brain, as well as fertility and sperm production in the testes. However, the study of VLC-PUFAs has been limited in fish. Seeking to address this gap in the scientific knowledge, the EU-funded LONGFA project investigated the biosynthesis of VLC-PUFAs in finfish. The gilt-head sea bream (Sparus aurata), a mainstay of European marine aquaculture, was used as a model species as its physiology is well understood. VLC-PUFAs are believed to proceed through consecutive 'elongation' reactions. In these reactions, enzymes known as elongases of VLC fatty acids (Elovl) catalyse from elongated PUFA substrates. In fish, two types of Elovl, namely Elovl2 and Elovl4, are key enzymes in the biosynthesis of VLC-PUFAs. Researchers identified two distinct Elovl4-like elongases from gilt-head sea bream, known as Elovl4a and Elovl4b. Analysis confirmed that Elovl4a and Elovl4b are expressed throughout the entire development of S. aurata embryos. This suggested that VLC-PUFA biosynthesis is necessary for early development. In adult fish, Elovl4a and Elovl4b were widely distributed in all the tissues studied, with the highest levels in brains and eyes of the fish. This confirmed the hypothesis that these organs are key metabolic sites for the synthesis of VLC-PUFAs. Researchers also studied the potential impact that some dietary strategies could have on normal development and the VLC-PUFA biosynthesis of rapid growing stages in S. aurata. The results of the LONGFA project will be transferred to other species of fish and used to improve their production. LONGFA results will therefore have significant benefits for the European aquaculture industry as a whole.
Keywords
Fatty acids, healthy fish, very long-chain polyunsaturated fatty acid, fish development, metabolism, aquaculture, biosynthesis, gilt-head sea bream, Sparus aurata, elongases, Elovl, dietary strategies
