不同盐度对斜带石斑鱼幼鱼血清离子浓度和激素水平的影响及其与鳃MRCs渗透调节功能的关系

Effects of various salinities stress on the relationship between concentrations of ions, hormones in serum and gill mitochondrion-rich cells osmotic regulations of Epinephelus coioides junveniles

为探究不同盐度对斜带石斑鱼幼鱼血清离子浓度和激素水平的影响及其与鳃线粒体丰富细胞(MRCs)渗透调节功能关系,实验将暂养于盐度为30的水体中的斜带石斑鱼幼鱼直接转移至盐度分别为5、10、20和30(对照组)的水体中,于7和15 d分别检测血清Na^+、K^+、Cl~–浓度和血清皮质醇(COR)水平,并于第15天观察幼鱼鳃MRCs分布和结构的变化。结果显示,随盐度升高,幼鱼血清Na^+、Cl~–浓度显著上升,而K^+浓度无显著变化;COR水平在盐度5和10实验组显著高于盐度20和对照组;随盐度上升,鳃MRCs体积增大,数量增多,且盐度20和对照组鳃MRCs体积显著大于盐度5和10实验组;鳃MRCs表面存在一个特殊的顶膜结构,在不同盐度下呈现不同形态:盐度5和10实验组中鳃MRCs顶膜开口较大,且其表面存在大量的微绒,而盐度20实验组和对照组中鳃MRCs的顶膜向内深陷形成了一个顶隐窝,开口较小,且其表面没有微绒毛。研究表明,斜带石斑鱼幼鱼鳃MRCs在盐度5的水体中可以很好地发挥渗透调节功能,使幼鱼在盐度5的水体中存活。

Effects of low salinity stress on the relationship between concentrations of ions, hormones in serum and gill mitochondrion-rich cells osmotic regulations of Epinephelus coioides juveniles were studied. E. coioides juveniles relayed in the seawater with salinity of 30 were directly transferred to water with salinities at 5, 10, 20,and 30, while those in seawater with salinity of 30 were taken as the control group. Na^＋, K^＋, Cl^– concentrations and cortisol（COR） in serum of E. coioides juveniles were investigated at 7 d and 15 d after transferring, and then the distributions and changes of the mitochondrion-rich cells（MRCs） in gills were studied. The results showed that Na^＋ and Cl^– concentrations in serum significantly increased with the rise of water salinity（P〈0.05）, while there were no significant differences with K^＋ concentration at different salinities（P〉0.05）. COR level in water with salinities 5 and 10 were significantly higher than that in water with salinity 20 and the control group（P〈0.05）. The volume and quantity of MRCs were increased, and the volume of MRCs in water with salinity 20 and control group were significantly greater than that in water with salinities 5 and 10（P〈0.05）. There was a special apical membrane in gill MRCs. The apical surfaces of gill MRCs in water with salinities 5 and 10 were generally flat with dense microvilli-like projections. In contrast, the gill MRCs in water with salinity 20 control group exhibited deeply invaginated surfaces with smaller orifices without projections In the light of this study, E. coioides juveniles can survive in water at salinities above 5, and the fresh water aquiculture of E. coioides is feasible.