a1 Unit of Nutrition, Aquaculture and Genomics NuAGe, Pôle d'Hydrobiologie INRA, Saint Pée-sur-Nivelle 64310, France
The objective of the present study was to characterise some important antioxidant enzymes and their relationships with retinoids and lipid peroxidation during rainbow trout (Oncorhynchus mykiss) early development. Eggs were incubated at 7°C until the swim-up stage whereupon fry were fed two semi-purified diets with 0 % (CO) and 8 % (OX) oxidised lipid respectively for 2 months at 17°C. The activities and gene expression of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) were determined as well as the levels of retinoids, F2-isoprostanes and lipid-soluble fluorescent products (LSFP) at various developmental stages. Only SOD had a detectable activity in embryos which increased during development and was linked with an increase of mitochondrial (SOD2) and cytosolic (SOD1) gene expression. SOD1 and SOD2 mRNA were more abundant in fry fed OX than in fry fed CO. CAT activity and gene expression also increased during development and were higher in fry fed OX compared with fry fed CO. Activity of Se-dependent GPX (Se-GPX) increased during development. The gene expression of cytosolic Se-GPX (GPX1) increased from hatching to 2-month-fed fry. Both phospholipid-hydroperoxide GPX and GPX1 genes were more expressed in fry fed OX than in fry fed CO. Retinoids decreased during development and, by 2 months, were lowered in fry fed OX compared with those fed CO. The levels of LSFP were higher in fry fed OX compared with fry fed CO. The present study demonstrates that antioxidant defence systems are active all through the development of rainbow trout and modulated by feeding oxidised lipid.
(Received July 30 2007)
(Revised October 23 2007)
(Accepted October 30 2007)
(Online publication December 06 2007)
Abbreviations: CAT, catalase; CO, semi-purified diet with 0 % oxidised lipid; CT, cycle threshold; dpf, days post-fertilisation; EF1α, elongation factor 1α; GPX, glutathione peroxidase; HPGPX, phospholipid-hydroperoxide glutathione peroxidase; LSFP, lipid-soluble fluorescent products; OX, semi-purified diet with 8 % oxidised lipid; Se-GPX, Se-dependent glutathione peroxidase; SOD, superoxide dismutase