Abstract: Toxic effects of SDS on hepatopancreas and gill of freshwater crayfish, Procambarus clarkii, relative to concentration (0, 35, 70, 140 and 280 mg•L^-1) were studied. Results show that SOD activities in the hepatopancreas and gill were closely related to concentration of and duration of the exposure to SDS. On the whole, SOD activity was induced by SDS low in concentration (≤70 mg•L^-1), and inhibited by SDS high in concentration (≥140 mg•L^-1), and tended to decline when exposure to SDS continued. SOD in hepatopancreas was more sensitive to high concentrations of SDS (≥140 mg•L^-1) than those in gill. CAT activities in the two organs were generally similar in variation trend, that is, rising first and declining later on，but degree of the variation was lower in gill than in hepatopancreas. Acid phosphatase (ACP) activity increased and then decreased in hepatopancreas, while it went down-up-down in gill. ACP in hepatopancreas was highly sensitive to SDS and induced in activity significantly after 24h of exposure. So ACP can be used as indicator of SDS stress. Reduced glutathione (GSH) in hepatopancreas and gill displayed a similar variation trend in content, that is, rising first and declining later on. Its content peaked at 48h and 24h in hepatopancreas and gill, respectively. GSH in hepatopancreas plays an important role in resisting SDS stress relatively low in concentration (≤140 mg•L^-1), while GSH in gill increased significantly within 24h of exposure (P<0.01), demonstrating that GSH in gill is more likely to be induced than that in hepatopancreas. It is quite obvious that crayfish can resist SDS stress by regulating its antioxidation system and metabolism, that most enmzymes in crayfish display apparent time/dose-dependent response, and that ACP in hepatopancreas and GSH in gill is very sensitive to SDS stress, and hence can be used as the potential bioindicator of SDS pollution in water.

Key words: Procambarus clarkii, SDS, antioxidative enzyme, antioxidating substance, acid phosphatase