Departmental Bulletin Paper クロマグロ若魚期から成魚期の脂肪蓄積発育変化

澤田, 好史  ,  阿川, 泰夫  ,  福岡, 祐大  ,  本領, 智紀  ,  倉田, 道雄  ,  岡田, 貴彦

To meet various demand of the market, it is necessaty to control lipid accumulation in cultured Pacific bluefin tuna (PBF). Previous studies elucidated the effect of rearing temperature on the lipid accumulation from larval to juvenile PBF. This study investigated the ontogenetic change of lipid accumulation by the histological examination in muscles and the function of lipid accumulation by the PPARy gene expression analysis in cultured PBF from juveniles to adults. Dorsal lateral muscle, ventral lateral muscle, and their red muscles were dissected from cultured 1-yr-old and 3-yr-old PBF to observe histologically by oil red o with hematoxylin and hematoxylin-eosin stain. These muscles were also examined the PPARy gene expression. Lipid was observed in the endomysium of dorsal lateral muscle, ventral lateral muscle, and their red muscles and no adipose cell was observed. Some muscle fibers accumulated lipid in the red muscle but others did not. For 1-yr-old fish, the PPARy gene expression was at high level, and on the other hand, it was at high level in the medium fatty ventral lateral muscle and dorsal lateral muscle. These suggested the elevated lipid metabolism in the lipid accumulated muscle fibers and sugar metabolism in the non lipid accumulated muscle fibers. The increased PPARy gene expression in the dorsal lateral muscle of the 3-yr-old fish indicated the expansion of distribution of adipose cells from the subdermal tissues of ventral muscle to the subdermal tissues of dorsal muscle.

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