急性淡水胁迫对斜带石斑鱼幼鱼鳃线粒体丰富细胞形态结构的影响

Impacts of acute fresh water stress on morphology and structure of mitochondrion-rich cells of Epinephelus coioides juvenile

为探讨淡水(盐度为0)对斜带石斑鱼(Epinephelus coioides)幼鱼鳃线粒体丰富细胞(MRCs)形态结构的影响,进一步探究其对鳃MRCs渗透调节机制的影响,以盐度30为对照,在斜带石斑鱼幼鱼急性淡水胁迫过程中,对鳃MRCs的结构变化进行光学显微镜(2、6、12、48 h)和扫描电镜观察(48 h).结果显示:淡水组鳃MRCs长径和短径均显著小于对照组(p<0.05),H.E染色较浅;鳃小片直径显著变宽(p<0.05),且鳃小片上增生出鳃MRCs;鳃MRCs表面存在一个特殊的顶膜结构,淡水组顶膜较为平坦,开口较大,且其表面存在大量微绒毛,对照组顶膜向内凹陷成一个开口较小的顶隐窝.推测在急性淡水胁迫下,斜带石斑鱼鳃MRCs的结构发生变化,导致其渗透调节功能部分丧失,幼鱼死亡,所以斜带石斑鱼幼鱼直接转入淡水时,不能长期存活.

To study impacts of fresh water on morphology and structure of mitochondrion-rich cells（ MRCs） of Epinephelus coioides juvenile under the stress of acute fresh water,the osmoregulatory function of MRCs and the structural changes in gill mitochondrion-rich cells were examined with LM in intervals of 2,6,12 and 48 h and with scanning electron microscope in 48 h. Results showed that the short and long diameter of MRCs in fresh water were significantly shorter than that in the control group except that the diameter of gill lamellaes were widened in fresh water（ p 0. 05）. There is a special apical membrane in gill MRCs. The apical surfaces of gill MRCs in fresh water were generally flat with dense microvilli-like projections. In contrast,the gill MRCs in the control exhibited deeply invaginated surfaces with smaller orifices. As results,under acute fresh water stress the structure of gill MRCs were changed and its osmoregulatory function was impaired. As consequence E. coioides juvenile cannot survive for a long time when transferred from seawater to fresh water with no acclimation.