Effect of of Artemia inherent fatty acid metabolism on the bioavailability of essential fatty acids for Octopus vulgaris paralarvae development

The aim of the present study was to determine the effect of Artemia metanauplii endogenous fatty acid (FA) metabolism in the actual availability of dietary essential fatty acids (EFA) for Octopus vulgaris paralarvae development. To this end, both Artemia metanauplii inherent radiolabelled FA metabolism and the Octopus vulgaris paralarvae FA metabolism, after being fed with Artemia metanauplii incubated with radiolabelled. FAs, were determined. Metanauplii were incubated in tissue culture plates during 12 h, with 0.3 mu M of a [1-C-14]FA, including either 18:3n-3, 20:4n-6 (ARA), 20:5n-3 (EPA) or 22:6n-3 (DHA), added individually to separate wells as their potassium salts bound to bovine serum albumin. A total of 3600 one-day-old paralarvae were reared up to 24 h in order to ensure the ingestion of a minimum amount of the labelled Artemia. Paralarvae rearing was performed in 4 L cylinder conical tanks at a density of 25 paralarvae L-1. Labelled Artemia metanauplii were added to each paralarvae rearing tank according to a specific [1-C-14]FA treatment. Artemia in vivo metabolism results showed a preferential catabolism of DHA, which was translated into (1) the lower incorporation of this FA into Artemia total lipids (TL)(2) the highest amount of de novo synthesis of shorter chain-length FAs, as a result of the beta-oxidation of the original DHA substrate. The registered amounts of radiolabelled substrates incorporated into O. vulgaris paralarvae TL fed with labelled Artemia metanauplii were extremely low. Nonetheless, certain amount of intact [1-C-14]ARA and [1-C-14]EPA was recovered into octopus paralarvae TL, and particularly into polar lipid classes, suggesting the possibility of using Artemia as a vehicle to provide ARA and EPA to octopus paralarvae without interfering their bioavailability for the de novo synthesis of phospholipids. On the other hand, and despite of the high amount of [1-C-14]18:3n-3 incorporated into Artemia TL, the FAs with the highest esterification rate into Anemia TAG (18:3n-3 and DHA) were also the lowest incorporated into paralarvae TL. Therefore, the present results suggest that O. vulgaris paralarvae may have a potentially low capacity to metabolise dietary TAG, and so, Artemia may not be the most appropriate vehicle to provide DHA to paralarvae.Spanish GovernmentSpanish Government [AGL2010-22120-CO3]Fundacao para a Ciencia e a Tecnologia (FCT)Portuguese Foundation for Science and Technology [SFRH/BD/76863/2011]FCTPortuguese Foundation for Science and Technology [IF/00576/2014