性成熟遅延系(3年成熟)雌ニジマスの卵表層胞糖タンパク質による同定

In unfertilized fish eggs there exist unique carbohydrate-rich glycoproteins, “hyosophorin”, as a component of the cortical vesicles (alveoli). In salmonid fish egg hyosophorin molecules oligo/polysialylglycan chains are known to be O-glycosidically linked to serine and threonine residues while hyosophorin molecules so far examined for other fish species including Oryzias latipes (medaka), Plecoglossus altivelis (ayu), and Tribolodon hakonensis (Japanese dace) contain large N-glycan chains. We found a new hyosophorin having large N-glycan chains in the unfertilized eggs of rainbow trout of delayed maturity (3-year maturating strain) bred in the Gunma Prefectural Fisheries Experimental Station at Kawaba. We have examined for hyoso-phorin of the unfertilized eggs of rainbow trout fishes including Donaldson, Steelhead, Nikko, and California. We have failed to detect such N-glycan type of hyosophorin as we found in the eggs of the 3-year maturating rainbow trout fish. Thus, we can safely conclude that hyoso-phorin, i.e. a glycoprotein of the Golgi-derived secretory vesicles, cortical alveoli, localized in the cortex of unfertilized eggs, can be used as a molecular marker to differentiate rainbow trout of delayed maturity (3-year maturating strain) at Kawaba from other usual 2-year maturat-ing rainbow trout fishes.