Abstract: In order to explore the effect of acute salinity stress on physiological, biochemical and morphological structure of tissues in S. purpurata, this paper studied the changes under acute salinity stress (high salinity 35 and low salinity 15) in S. purpurata gill tissue microstructure, enzyme and coelomic fluid of Na+/K+-ATP, 3 non-specific immune factors of SOD, CAT and POD in gill tissue. The results of gill tissue structure changes indicated that comparing to natural seawater control group, there was significant difference in the gill lamellas space of each salinity stress group. After 3 h low salinity treatment, the gill lamellas space and shrinking degree showed an enlarging trend with the increase of stress hours, compared with that of natural saewater group. In high salinity stress group, the gill lamellas space and shrink degree decreased first and then increased gradually. While,  in the low salinity stress group at each time point, changes in  gill lamellas mophological structure were more obvious than that in high salinity stress group. Na+/K+-ATPase activity of gill tissues increased under low salinity stress, but decreased under high salinity stress. Salinity changes also affected the activities of SOD, CAT and POD in the gill and coelomic fluid of S. purpurata. The responses of different tissues to acute salinity stress were significantly different. For coelomic fluid, SOD was the first enzyme responded to acute salinity, while, POD activity was changed firstly in gill in order to adapt to the acute change of salinity. The SOD and CAT activity of high salinity stress in the coelomic fluid did not differ from that of the control at 1 h and 3 h (P>0.05). After 5 h salinity stress, the activities of SOD and CAT significantly increased at 5 h and significantly down-regulated at 7 h, then significantly increased at 24 h compared to that of the control (P<0.05). The CAT and POD activity in the coelomic fluid decreased first to the lowest point at 7 h and 3 h under low salinity stress, respectively (P<0.05). After that it returned to the control group level. In brief, all results observed in this study demonstrated that the response patterns of 3 non-specific immune factors (SOD, CAT, POD) and Na+/K+-ATPase activity under acute salinity stress were different on S. purpurata, and also, S. purpurata probably adjusted their gills structure to survive the acute salinity stress.

Key words: salinity, Saxidomus purpurata, gill, Na+/K+-ATPase, non-specific immune factors, SOD, CAT, POD

摘要： 为探明急性盐度胁迫对狭盐性贝类紫石房蛤（Saxidomus purpurata）组织形态结构及生理生化的影响，研究了急性高盐（盐度35）和低盐（盐度15）胁迫下紫石房蛤鳃组织显微结构、Na+/K+-ATP酶和体腔液、鳃组织中SOD、CAT和POD 3种非特异性免疫因子的变化。鳃组织结构变化结果显示，与自然海水对照组相比，急性盐度胁迫实验组紫石房蛤鳃丝间距均呈现显著差异。盐度胁迫3 h起，低盐胁迫组紫石房蛤鳃丝皱缩程度和鳃间距与自然海水组相比总体呈现随胁迫时间增加而增大的趋势；高盐胁迫组鳃丝则表现为先皱缩后饱满，鳃间距呈逐渐缩小后逐步增大的趋势；低盐胁迫各时间点，鳃丝形态结构变化较相对应的高盐胁迫组明显。紫石房蛤鳃组织Na+/K+-ATP酶在急性低盐胁迫下活力升高，急性高盐胁迫下活力降低。24 h低盐和高盐度急性胁迫对紫石房蛤SOD、CAT和POD酶活力的影响呈现组织特异性。体腔液中以SOD率先对盐度胁迫产生应答，鳃组织中则以POD的响应最为快速。急性高盐胁迫下紫石房蛤体腔液中SOD和CAT活力在胁迫1 h、3 h后无明显变化，胁迫5 h后显著上升；胁迫7 h后显著下降；胁迫24 h后又显著上升，变化趋于一致（P<0.05）。急性低盐胁迫下紫石房蛤体腔液中CAT和POD酶活力分别在7 h和3 h显著下降至最低点，之后逐步趋于对照组水平（P<0.05）。结果提示，急性盐度胁迫下紫石房蛤体腔液和鳃组织中SOD、CAT和POD 3种非特异性免疫因子及鳃组织中Na+/K+-ATP酶的响应方式不同，紫石房蛤可能通过改变鳃组织形态结构从而适应外界盐度的骤然变化。

关键词: 盐度, 紫石房蛤, 鳃组织, Na+/K+-ATP酶, 非特异性免疫因子, SOD, CAT, POD