LC-PUFA biosynthesis in fish: A phylogenetic and/or environmental question?
The study of long-chain (≥C20) polyunsaturated fatty acids (LC-PUFA) biosynthesis in farmed fish has been a topic of interest within the scientific community. Investigate the ability to produce the physiologically important arachidonic acid (20:4n-6, ARA), eicosa-pentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA) is crucial in the aquaculture industry to know the essential fatty acid requirements of farmed species. Knowledge of the biosynthetic capacity to obtain LC-PUFA from C18 PUFA allows the proper use of vegetable-based diets that lack the former. Several studies have shown that the endogenous capacity to produce LC-PUFA depends on the complement and function of fatty acyl desaturase (fads) and elongase of very long chain fatty acid (elovl) genes that differ between species. Furthermore, the biosynthetic capacity can be modulated by environmental factors such as salinity or by the LC-PUFA supply in the diet. The present study aims to elucidate how the phylogenetic and environmental parameters influence the LC-PUFA biosynthetic capacities of different teleost species of interest in fish farming. This aim was addressed by, first, characterising the LC-PUFA biosynthesis in a relatively low-trophic level teleost, the grass carp Ctenopharyngodon idella, and second, establish-ing how both dietary fatty acid composition and salinity can modulate the LC-PUFA bi-osynthetic capacity of two marine species occupying intermediate trophic levels, namely Solea senegalensis and Chelon labrosus.