Biochemical Studies on Smoltification of Salmon

幼鲑鱼在孵化后从河流迁移到海洋（parr-smolt转化）。受精是一种复杂的现象，包括多种形态、生理和行为变化。在体内的“银发”现象中，鸟嘌呤在甲状腺激素的调节下在皮肤中积累。本研究有助于我们从生化机制的角度对parr-smolt转化的基本认识。用兔抗血清对马苏鲑（Oncorhynchus masou）血清进行免疫印迹和双向聚丙烯酰胺凝胶电泳，分析了马苏鲑（Oncorhynchus masou） 5 - 6月parr-smolt转化过程中的血清蛋白。一种新蛋白（mol. wt. 43,000-50,000, p1 5.0-5.5）出现在幼崽血清中，而幼崽血清中没有。该蛋白似乎是一种雏型特异性血清蛋白。通过免疫电泳和放射性鸟嘌呤放射自显影，在幼崽或幼崽血清中观察到4种鸟嘌呤结合蛋白。雏鸟特异性蛋白可能与鸟嘌呤结合蛋白有关。研究了虹鳟、虹鳟肝脏嘌呤核苷磷酸化酶（PNPase）活性与熏蒸期的相关性。结果表明，肝脏嘌呤核苷磷酸化酶活性的变化与虹鳟皮肤中鸟嘌呤的积累密切相关。发现了两个分离的活动峰。第一个高峰出现在3 ~ 4月，第二个高峰出现在5月下旬，分别对应于fi13EA\: 1的鸟嘌呤积累和除垢引起的鸟嘌呤恢复。这些结果有力地表明，肝脏中鸟嘌呤的释放与雌鱼转化的表型有关。

Young anadoromous salmonids are known to migrate from the river to the sea after smoltification (parr-smolt transformation). Smoltification is a complex phenomenon comprised of various morphological, physiological and behavioral changes. In the body13EA\ : 'silvering' phenomenon, guanine is accumulated in the skin under regulation by thyroid hormone. This research is relevant to our basic understanding of the parr-smolt transformation from the point-of-view of biochemical mechanisms.We analyzed serum proteins during parr-smolt transformation (May-June) of masu salmon (Oncorhynchus masou) by two-dimensional polyacrylamide gel electrophoresis and Western blotting using a rabbit antiserum raised against smolt serum. A new protein (mol. wt. 43,000-50,000, p1 5.0-5.5) appeared in serum of smolt but not parr. This protein seems to be a smolt-specific serum protein. Four guanine-binding proteins were observed in parr or smolt serum by immunoelectrophoresis and autoradiography using radioactive guanine. The smolt-specific protein and guanine-binding protein may be related.The correlation between purine nucleoside phosphorylase (PNPase) activity in liver of steelhead trout, Oncorhynchus mykiss, and smoltification stages was studied. It was found that changes of purine nucleoside phosphorylase activity in the liver wer13EA\ : e closely associated with the accumulation of guanine in the skin of steelhead trout. Two separated peaks of activity were found. The first peak occured during March to April and the second peak was seen in late May, which was corresponded to the fi13EA\ : rst accumulation of guanine and the restoration of guanine caused by descalation, respectively. These results strongly suggest that the liberation of guanine in liver was correleated to phenotype of parr-smolt transformation in anadromous steelhead trout.