Metabolism and Functions of Lipids and Fatty Acids in Teleost Fish

Abstract

Lipids and their constituent fatty acids are, along with proteins, the major organic constituents of fish, and they play major roles as sources of metabolic energy for growth including reproduction, and movement including migration. Furthermore, the fatty acids of fish lipids are rich in ω3 long chain, highly unsaturated fatty acids (n-3 HUFA) that have particularly important roles in animal nutrition, including fish and human nutrition, reflecting their roles in critical physiological processes. Indeed, fish are the most important food source of these vital nutrients for man Thus, the long standing interest in fish lipids stems from their abundance and their uniqueness. This review attempts to summarise our present state of knowledge of various aspects of the basic biochemistry, metabolism and functions of fatty acids, and the lipids they constitute part of, in fish, seeking where possible to relate that understanding as much to fish in their natural environment as to farmed fish. In doing so, it highlights the areas that require to be investigated in greater depth and also the increasing application of molecular technologies in fish lipid metabolism which will fascilitate further advances through molecular biological and genetic techniques including genomics and proteomics.

Stress and expression of cyclooxygenases (cox1, cox2a, cox2b) and intestinal eicosanoids, in Atlantic salmon, Salmo salar L.

“…The clear preference of production of PGE 2 over PGE 3 , and a general preference of n-6 eicosanoids over their n-3 counterparts (eg PGF 2α and PGF 3α , and also the stable nonenzymatic hydrolytic products of PGI 2 and PGI 3 , 6-keto-PGF 1α and d17-6-keto-PGF 1α respectively) clearly indicates the importance of these metabolites despite AA by far has the lowest concentration in cellular membranes compared to EPA and DHA. This further suggests the possible role of phosphatidylinositol phospholipids, being enriched in AA as an important contributor of AA for eicosanoid production, although definitive data are still not available (Tocher 2003). It is also likely that other mechanisms in the eicosanoid signaling pathway have evolved discriminating in favor of AA.…”

Sex-dependent accumulation and maternal transfer of Dechlorane Plus flame retardant in fish from an electronic waste recycling site in South China

“…In eggs of crucian carp, lipid content ranged from 1.0% to 3.8% (median: 2.9%), which were one order of magnitude lower than those (median: 33%) in northern snakehead (Table 1). It was reported that, for fish with low lipid content eggs (<5%), there were large differences in lipid composition between the eggs and the body (Tocher, 2003). Compared to the mother tissues, these eggs contained a much larger percentage of polar lipids, e.g., phosphatidylcholine (Tocher, 2003); which may affect the partitioning of lipophilic chemicals between the mother and the eggs.…”

Effects of dietary fish oil substitution by Echium oil on enterocyte and hepatocyte lipid metabolism of gilthead seabream (Sparus aurata L.)

“…Therefore, HUFA are essential fatty acids (EFA) for marine fish, and are important as structural components of cell membranes Marsh, 2008), eicosanoids precursors (Tocher, 2003;Bell et al, 2006;Villalta et al, 2007) and regulators of gene expression (Zheng et al, 2005;Miller et al, 2008;Leaver et al, 2008). The fatty acid profile of VO, together with this poor ability of marine fish to convert C 18 polyunsaturated fatty acids (PUFA) to HUFA, lead to important changes in the fatty acid composition of flesh of fish fed VOs, which include decreased n-3 HUFA and increased fat and LA contents Menoyo et al, 2004;Bell et al, 2006;Benedito-Palos et al, 2007;Díaz-López et al, 2009;Fountoulaki et al, 2009).…”

“…Thus, Echium oil (EO) has a good n-3/n-6 PUFA balance as well as an interesting profile with its high content of unusual fatty acids (SDA and GLA) that are of increasing pharmacological interest based on their competitive and inhibitory effects in the production of proinflammatory eicosanoids derived from ARA (Tocher, 2003;Villalta et al, 2007;Chilton et al, 2008;Whelan, 2009). The high levels of SDA, compared to LNA, may also facilitate its conversion into n-3 HUFA, since it does not require the first, rate-limiting, Δ6 desaturation step.…”