Towards Fish Lipid Nutrigenomics: Current State and Prospects for Fin-Fish Aquaculture

Abstract

Lipids are the predominant source of energy for fish. The mechanisms by which fish allocate energy from lipids, for metabolism, development, growth and reproduction are critical for understanding key life history strategies and transitions. Currently, the major lipid component in aquaculture diets is fish oil (FO), derived from wild capture fisheries that are exploited at their maximum sustainable limit. The increasing demand from aquaculture for FO will soon exceed supply and threaten the viability of aquaculture. Thus, it is essential to minimize FO use in aquaculture diets. This might be achieved by a greater understanding of lipid storage and muscle growth, or the identification of alternatives to FO in feeds. This review focuses on recent research applying molecular and genomic techniques to the study of fin-fish lipid metabolism from an aquaculture perspective. Accordingly, particular emphasis will be given to fatty acid metabolism and to highly unsaturated fatty acid (HUFA) biosynthesis, and to the transcriptional mechanisms and endocrine factors that regulate these processes in fish. Comparative studies of gene function and distribution are described which, when integrated with recent fish genome sequence information, provide insights into lipid homeostasis and the outcomes associated with the replacement of FO in fish diets.

Compared to fish oil alone, a corn and fish oil mixture decreases the lipid requirement of a freshwater fish species, Carassius auratus gibelio

“…Fish as well as other vertebrates are well known to be capable of de novo synthesis of SFA and desaturation by including a double bound stearoyl-CoA desaturase, and the core products are 16:0, 18:0, 16:1n−7 and 18:1n−9 (Henderson, 1996;Tocher, 2003). ACC1 and FAS are the rate-limiting enzymes during the process of SFA synthesis (Leaver et al, 2008). The effects of dietary lipid concentrations on ACC1 expression have been poorly studied in fish.…”

“…Anchovy oil used in the present study only contains 3.31% 18:2n−6 and 0.77% 20:4n−6 of the total FAs, respectively. In addition, 18:3n− 3 competes with 18:2n− 6 for △6 desaturase and △6 desaturase is more active toward n−3 FAs (Leaver et al, 2008;Ruyter et al, 2000;Simopoulos, 2002), which inhibit the conversion efficiency of dietary 18:2n−6. It further makes the production of 20:4n−6 cannot be insured by insufficient dietary 18:2n−6 content.…”

“…Until recently, fish oil was still the main lipid source used in the formulation of commercial aqua-feeds, owing to its ready availability, low price and richness in LC-PUFA (Leaver et al, 2008;Turchini et al, 2009). It is estimated that approximately 90% of fish oil production has been consumed in aqua-feeds.…”

Molecular characterization of a gilthead sea bream (Sparus aurata) muscle tissue cDNA for carnitine palmitoyltransferase 1B (CPT1B)

“…The regulation of fatty acid and lipid metabolism at the gene level has been poorly studied in fish species, despite the fact that problems related to fatty acid metabolism are of primary importance to modern aquaculture practices (Leaver et al, 2008). Molecular studies concerning CPT1 expression in fish are presently limited to rainbow trout (Oncorhynchus mykiss), i.e.…”

Omega-3 long-chain polyunsaturated fatty acids and aquaculture in perspective

“…The up-regulation in fish fed VO is likely due mainly to relieving the suppression of gene expression exerted by dietary LC-PUFA, especially DHA (Leaver et al, 2008b;Thomassen et al, 2012), although increased substrate (e.g. LNA) concentration may also stimulate expression (Cleveland et al, 2012).…”