Regulation of FADS2 expression and activity in European sea bass (Dicentrarchus labrax, L.) fed a vegetable diet

Comp Biochem Physiol B Biochem Mol Biol. 2010 Aug;156(4):237-43. doi: 10.1016/j.cbpb.2010.03.008. Epub 2010 Apr 2.

Abstract

Supplies of marine fish oils are limited, and continued growth in aquaculture production dictates that lipid substitutes in fish diets must be used without compromising fish health and product quality. In this study, the total substitution of a fish meal and fish oil by a blend of vegetable meals (corn, soybean, wheat and lupin) and linseed oil in the diet of European sea bass (Dicentrachus labrax) was investigated. Two groups of European sea bass were fed with fish diet (FD) or vegetable diet (VD) for 9months. VD, totally deprived of eicosapentaenoate (EPA; 20:5n-3) and docosahexaenoate (DHA; 22:6n-3), revealed a nutritional deficiency and affected growth performance. Whilst VD induced a significant increase in fatty acid desaturase 2 (FADS2) and sterol binding regulatory element-binding protein 1 (SREBP-1) mRNA levels, the desaturation rate of [1-(14)C]18:3n-3 into [1-(14)C]18:4n-3, analysed in microsomal preparations using HPLC method, did not show an upregulation of FADS2 activities in liver and intestine of fish fed VD. Moreover Western-blot analysis did not revealed any significant difference of FADS2 protein amount between the two dietary groups. These data demonstrate that sea bass exhibits a desaturase (FADS2) activity whatever their diet, but a post-transcriptional regulation of fads2 RNA prevents an increase of enzyme in fish fed a HUFA-free diet. This led to a lower fish growth and poor muscle HUFA content.

MeSH terms

  • Animal Feed
  • Animals
  • Aquaculture
  • Bass / genetics
  • Bass / growth & development
  • Bass / metabolism*
  • Diet*
  • Fatty Acid Desaturases / genetics
  • Fatty Acid Desaturases / metabolism*
  • Fatty Acids / analysis
  • Fish Proteins / genetics
  • Fish Proteins / metabolism*
  • Gene Expression Regulation
  • Intestines / enzymology
  • Liver / enzymology
  • PPAR alpha / genetics
  • PPAR alpha / metabolism
  • Sterol Regulatory Element Binding Protein 1 / genetics
  • Sterol Regulatory Element Binding Protein 1 / metabolism
  • Vegetables

Substances

  • Fatty Acids
  • Fish Proteins
  • PPAR alpha
  • Sterol Regulatory Element Binding Protein 1
  • Fatty Acid Desaturases