In vivo metabolism of unsaturated fatty acids in Octopus vulgaris hatchlings determined by incubation with 14C-labelled fatty acids added directly to seawater as protein complexes

The highmortalities observed during Octopus vulgaris paralarvae culture have been associated with a nutritional imbalance, with long-chain polyunsaturated fatty acids (LC-PUFA) appearing to have a critical role. In order to determine the in vivo capability of O. vulgaris hatchlings to incorporate and metabolise unsaturated fatty acids (FA), hatchlings were incubated in flat-bottom 6-well tissue culture plates at a density of 90 hatchlings/well in 10 mL of seawater (36‰). Incubations were performed with gentle stirring at 21 °C for 6 h with 0.2 μCi (0.3 μM) of [1−14C]-labelled FA including 18:1n−9, 18:2n−6, 18:3n−3, 20:4n−6 (ARA), 20:5n−3 (EPA) or 22:6n−3 (DHA), which were added directly to the seawater as their potassium salts bound to bovine serum albumin (BSA). A control treatmentwithout [1−14C]FA was also assessed. O. vulgaris hatchlings not only possessed the ability to incorporate FA bound to BSA, but also to esterify them into phospholipid, with marked specificity. [1−14C]DHA and [1−14C]C18 FA substratesweremainly esterified into phosphatidylcholine, while [1−14C]ARA and [1−14C]EPA were esterified into phosphatidylethanolamine.