February 15-18, 2009 Washington State Convention Center Seattle ...

DELTA 6 DESATURASE GENE IS DIFFERENTIALLY EXPRESSED IN THE INTESTINE
OF SEA BASS Dicentrarchus labrax FAMILIES EXHIBITING DIFFERENT GROWTH
POTENTIAL ONTO VEGETABLE-BASED-DIET
Florian Geay, Ester Santigosa, Thierry Tonon, Laurent Corcos, Pierre Boudry, Beatrice Chatain,
Jose Zambonino-Infante, Marc Vandeputte, Chantal Cahun and David Mazurais
Marine fish exhibit low HUFA (Highly Unsaturated Fatty Acids) synthesis capacity which represents a bottleneck for the substitution
of fish oils by vegetal oils in their feed. However, as some recent data revealed differential adaptability of fish to fish
oil replacement by vegetal oil, we assessed the regulation of the HUFA metabolic pathway in sea bass (Dicentrarchus labrax)
selected from two families (F1 and F2) that displayed similar growth rates when fed fish-based-diet (FD) but different ones
(F2>F1) when fed vegetable-based-diet (VD). The expression of the delta 6 desaturase (D6D) and elongase 5 (ELOVL5) genes
that encode two key enzymes involved in desaturation and elongation steps of HUFA synthesis were investigated in two major
metabolic organs, the liver and the intestine.
The switch from a FD to a VD induced an increase of D6D mRNA levels in the liver and intestine of both F1 and F2 fish-families.
The expression level of D6D was significantly higher in the intestine of F2 fish whatever diet considered (Figure 1). In opposite,
no difference in ELOVL5 expression was evidenced due to diets or families (Figure 2).Work in progress will determine
if the higher level of D6D expression in the intestine of F2 fish is related to an increase in the activity of desaturation and if this
is associated with a modification of fatty acids profiles in the muscle.
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