Hwang P P, Lee T H, Weng C F, Fang M J, Cho G Y
Institute of Zoology, Academia Sinica, Taipei, Taiwan 115, Department of Taiwan 106, Republic of China.
Physiol Biochem Zool. 1999 Mar-Apr;72(2):138-44. doi: 10.1086/316660.
The purpose of this study is to provide biochemical evidence for the functions of the mitochondria-rich cell (MR cell) in the yolk-sac epithelium of the developing larvae of tilapia Oreochromis mossambicus. Western blotting with the antibody (6F) raised against avian Na-K-ATPase alpha1 subunit demonstrated the presence of Na-K-ATPase in yolk-sac epithelium of tilapia larvae and about 1. 46-fold more of the enzyme in seawater larvae than in freshwater ones. The yolk-sac MR cells were immunoreacted to the antibody (alpha5) against the alpha subunit of avian Na-K-ATPase and were double-labeled with anthroylouabain and dimethylaminostyrylethyl-pyridiniumiodine, suggesting the existence and activity of Na-K-ATPase in these cells. Binding of 3H-ouabain in the yolk sac of seawater larvae was much higher than in that of freshwater larvae (4.183+/-0.143 pmol/mg protein versus 1.610+/-0. 060 pmol/mg protein or 0.0508+/-0.0053 pmol/yolk sac versus 0. 0188+/-0.0073 pmol/yolk sac). These biochemical results are further evidence that yolk-sac MR cells are responsible for a major role in the osmoregulatory mechanism of early developmental stages before the function of gills is fully developed.
本研究的目的是为莫桑比克罗非鱼发育中幼体卵黄囊上皮中富含线粒体的细胞（MR细胞）的功能提供生化证据。用针对禽类Na-K-ATP酶α1亚基产生的抗体（6F）进行的蛋白质免疫印迹分析表明，罗非鱼幼体的卵黄囊上皮中存在Na-K-ATP酶，海水幼体中的该酶含量比淡水幼体中的约高1.46倍。卵黄囊MR细胞与针对禽类Na-K-ATP酶α亚基的抗体（α5）发生免疫反应，并与蒽基哇巴因和二甲基氨基苯乙烯基乙基碘化吡啶进行双重标记，表明这些细胞中存在Na-K-ATP酶并具有活性。海水幼体卵黄囊中3H-哇巴因的结合量远高于淡水幼体（分别为4.183±0.143 pmol/mg蛋白质和1.610±0.060 pmol/mg蛋白质，或0.0508±0.0053 pmol/卵黄囊和0.0188±0.0073 pmol/卵黄囊）。这些生化结果进一步证明，在鳃功能完全发育之前，卵黄囊MR细胞在早期发育阶段的渗透调节机制中起主要作用。
