首先将熊本牡蛎(Crassostrea sikamea)暴露于不同质量浓度(0、50、100、500、1000和5000 mg/L)悬沙中15d后,再将受试牡蛎转移到干净海水中恢复培养15 d,观察牡蛎的存活率,检测鳃丝中Na+-K+-ATP酶、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性变化、鳃细胞DNA损伤情况和肌肉中RNA/DNA比率变化,探讨悬沙对牡蛎的影响.结果表明,悬沙暴露试验后,本研究所设悬沙浓度对牡蛎存活率几乎无影响,但当悬沙质量浓度≥500mg/L时,鳃丝中Na+-K+-ATP酶、SOD和CAT活性开始显著降低,鳃细胞中开始检测到明显的DNA损伤,反映牡蛎生长状况的RNA/DNA比率也较对照组明显减小(P＜0.05).这些受损牡蛎经干净海水培养15 d后,检测的生理生化指标虽有一定程度的恢复,但仍未恢复到对照组和低浓度悬沙组的水平.可见,较高水平的悬沙胁迫对牡蛎并没有产生致命的影响,依据常规的生态毒理学指标如存活率并不能得出有效的评价结果,但分子细胞水平上的各指标就能比较灵敏地反映悬沙胁迫的影响.%We evaluated the effects of suspended solids on the survival and physiology of the Kumamoto oyster, Crassostrea sikamea. The oysters were exposed to 0, 50, 100, 500, 1 000, or 5 000 mg/L suspended solids (SS) for 15 d then returned to clean seawater, without SS, for 15 d. We monitored survival and measured Na+-K+-ATPase, SOD, CAT, and DNA damage in the gills and the RNA/DNA ratio in the muscle tissue. There was no difference in survival among the groups after 15 d. Na+-K+-ATPase, SOD, and CAT activity and the RNA/DNA ratio were significantly lower in the groups exposed to &500 mg/L SS after 15 d. Furthermore, there were obvious signs of DNA damage in these groups. We observed some recovery in these indices following transfer to clean seawater. However, recovery was incomplete and levels did not return to those of the controls. Our results suggest that these physiological and biochemical indices may be more sensitive than survival as indicators of exposure to increased SS in C. Sikamea.
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