全氟辛烷磺酸对真鲷鳃抗氧化酶和组织损伤的影响

Effects of Perfluorooctanesulfonate(PFOS) on Antioxidant Enzyme in the Gill of Pagrosomus major and Damage to Its Tissues

为了探讨全氟辛烷磺酸(PFOS)对真鲷(Pagrosomus major)的毒性及致毒机理,采用半静态毒性试验方法研究PFOS对真鲷的96 h急性毒性,并分析低浓度(0.1 mg.L-1)、中浓度(1.0 mg.L-1)和高浓度(2.0 mg.L-1)PFOS胁迫对真鲷鳃组织超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性,脂质过氧化物(MDA)含量以及组织损伤的影响。结果表明,PFOS对真鲷的96 h半致死浓度〔ρ(LC50)〕为22.56 mg.L-1。在PFOS胁迫阶段,低浓度组真鲷鳃组织SOD活性呈现先受诱导后受抑制的趋势,而中、高浓度组受到显著抑制(P<0.05),胁迫15 d时高浓度组抑制率为14.86%;各浓度组CAT活性的变化趋势呈"U"型,7和15 d时高浓度组诱导率分别为40.53%和62.32%;低浓度组POD活性在胁迫1 d时呈受诱导效应,之后下降至对照组水平(P>0.05),中、高浓度组则呈现先受抑制后受诱导的趋势,胁迫15 d时高浓度组诱导率为63.05%;MDA含量变化没有表现出明显的规律性。在净水恢复结束时,各浓度组真鲷鳃组织SOD活性恢复到对照组水平,而CAT、POD活性和MDA含量与对照组相比仍有显著差异(P<0.05)。在PFOS胁迫下真鲷鳃组织出现鳃丝上皮脱落与鳃丝融合现象,病变程度随着暴露浓度的增加和暴露时间的延长而加深。可见,PFOS可对真鲷鳃组织产生多个层面的毒性效应。

The semi-static toxicity test method was used to determine 96 h acute toxicity of PFOS （ perfluorooctanesulfon- ate） to Pagrosomus major so as to explore toxicity of PFOS to the fish and mechanism of the toxieation and analyze effects of the substance varying in concentration, 0. 1 , 1.0 and 2.0 mg ·L^-1 on SOD, CAT, and POD activities and MDA con- tent in gills and damage to the tissue. Results show that the 96 h - LC50 of PFOS to P. major was 22. 56 mg·L^-1. In the group of fish exposed to 0. 1 mg·L^-1 of PFOS, SOD activity in gills was induced first and then inhibited, while in the groups of fish exposed to 1.0 and 2. 0 mg ·L^-1 of PFOS, SOD activity was significantly inhibited （P 〈 0. 05 ） and the SOD inhibition rate reached 14. 86% on D15 in the group exposed to 2.0 mg·L^-1 of PFOS. CAT activities in all the groups followed a similar ＂U＂ pattern and the CAT activity induction rate reached 40. 53% and 62. 32% on D7 and D15, respectively, in the group exposed to 2. 0 mg ·L^-1 of PFOS. POD activity in the low dosage group increased significantly （ P 〈 0. 05 ） on D1 and declined afterwards down to the level in the control, while in the moderate and high dosage groups, it was first inhibited and then induced, with induction rate reaching 63.05% on D15 in the high dosage group. The varia- tion of MDA content did not show any pattern. At the end of clean water recovery period, SOD activity in aU the three groups returned to the level in the control, while CAT and POD activities and MDA content still differed significantly between the PFOS treated groups and the control group （P 〈 0. 05）. Under the stress of PFOS, the fish was found to have its gill filaments losing their epitheles and getting merged, and the lesion aggravated with the concentration of the toxi- cant and the duration of the exposure. The findings of this study indicate that PFOS may bring about multiple levels of toxic effects on the gill of P. major.