Replacement of Marine Fish Oil with de novo Omega-3 Oils from Transgenic Camelina sativa in Feeds for Gilthead Sea Bream (Sparus aurata L.)

Omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA) are essential components of the diet of all vertebrates and. The major dietary source of n-3 LC-PUFA for humans has been fish and seafood but, paradoxically, farmed fish are also reliant on marine fisheries for fish meal and fish oil (FO), traditionally major ingredients of aquafeeds. Currently, the only sustainable alternatives to FO are vegetable oils, which are rich in C18 PUFA, but devoid of the eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) abundant in FO. Two new n-3 LC-PUFA sources obtained from genetically modified (GM) Camelina sativa containing either EPA alone (ECO) or EPA and DHA (DCO) were compared to FO and wild-type camelina oil (WCO) in juvenile sea bream. Neither ECO nor DCO had any detrimental effects on fish performance, although final weight of ECO-fed fish (117 g) was slightly lower than that of FO- and DCO-fed fish (130 and 127 g, respectively). Inclusion of the GM-derived oils enhanced the n-3 LC-PUFA content in fish tissues compared to WCO, although limited biosynthesis was observed indicating accumulation of dietary fatty acids. The expression of genes involved in several lipid metabolic processes, as well as fish health and immune response, in both liver and anterior intestine were altered in fish fed the GM-derived oils. This showed a similar pattern to that observed in WCO-fed fish reflecting the hybrid fatty acid profile of the new oils. Overall the data indicated that the GM-derived oils could be suitable alternatives to dietary FO in sea bream

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Not AvailableIn vertebrates, myogenic regulatory factors (MRFs) play an important role in muscle growth through the pro- cesses of cell determination and differentiation. Herein, we report the molecular characterisation of two MRFs, myogenin (myog) and myogenic factor 6 (myf6) in Indian snow trout Schizothorax richardsonii. The full length mRNA sequence of Srmyog and Srmyf6 was 1437 and 1296 bp, with an ORF of 762 and 720 bp, encoding a putative protein of 253 and 239 amino acids, respectively. In silico analysis and predicted tertiary protein structure revealed that both these nuclear localized MRFs contained the highly conserved basic helix loop helix motif, to potentially aid in dimerization with functional partners and DNA binding. Phylogenetically, the de- duced protein sequences of Srmyog and Srmyf6 closely clustered with high altitude dwelling cyprinids, sug- gesting common ancestry. Tissue-wise, transcripts of Srmyog and Srmyf6 were abundant in skeletal muscle, affirming their muscle-specific role. Moreover, Srmyog was highly expressed in females as compared to males, whereas Srmyf6 expression was higher in older-bigger individuals as compared to younger-smaller fish. Nutritional status (fed-starved-refed) and diet composition (protein and lipid levels) had no significant influence on Srmyog expression. But, Srmyf6 expression was elevated in fishes re-fed after 3 weeks of starvation and in those fed low protein diet. Only rearing temperature was found to coherently influence Srmyog and Srmyf6 transcripts, with highest expression at 18 °C, which favoured growth. Overall, molecular characterisation of the structure and regulation of these MRFs is the first step taken towards deciphering slow growth in this important Himalayan cyprinid.Not Availabl