| perfluorooctane sulfonate（PFOS）is a new type of persistent environmentalpollutants, it can cause multiple level toxic effect on organism. Because of physicaland chemical properties of PFOS, it had been stop to production, sale and use by lotsof country, but there is potential threat to wildlife and human, the toxicity of studies toPFOS on a variety of organisms that has become a hot issue. In this paper, we studiedthe effect of PFOS on activities of antioxidantive enzymes （SOD, CAT, POD, GSH,MDA, GST） and the gene expression on Perna viridis and red sea bream, the damageof gill and liver were observed with sections. The toxicity of PFOS was been studiedwith the changes of indicators of biology which exposed under PFOS solution andclean seawater. The main findings are following:1、96h–LC50values of PFOS on Perna viridis was68.3mg/L，and the safeconcentration of PFOS on Perna viridis was6.83mg/L. The PFOS chronic toxicityexposure concentrations were set to be1,2,4,8mg/L with the result of acute toxicityexperiments of PFOS on Perna viridis. After the PFOS exposure of Perna viridis,SOD activities increased in mantle and decreased in visceral significantly at theconcentration of1mg/L （p<0.05）, which decreased in mantle and increased invisceral with the increasing concentration of PFOS （p<0.05）.GSH content in mantleand visceral of Perna viridis was induced compared with the control（P<0.05）, withthe increasing exposure time, which was inhibited in each group after15d exposureof PFOS （p<0.05）.The MDA content in mantle increased significantly during theperiod of exposure of PFOS; while MDA content in visceral decreased firstly and thenincreased during the stress stage of PFOS. During the phase of recovery with clearseawater, SOD activities recovered to the same level with control group, however, there was a rising tendency for all the content of GSH and MDA in2tissues of Pernaviridis after a7d recovery （p<0.05）.The results showed that PFOS solutions exposurecould cause oxidative stress on mantle and visceral of Perna viridis, but the stresscompressed by PFOS could be recovered quickly after released a short period.2、96h–LC50 values of PFOS on red sea bream was22.56mg/L. The PFOSchronic toxicity exposure concentrations were set to be0.1,1.0,2.0mg/L with theresult of acute toxicity experiments of PFOS on red sea bream. In the gill, SODactivities increased in the PFOS stress stage, the induction of the low concentrationgroup was12.14%in1d, with the stress time, every concentrations were in thesuppression level, the inhibition rates of the low and the high concentration groupwere16.01%and14.86%in15d; SOD activities in the liver showed a significantdose-effect relationship in the end of exposure, SOD activities is reduced with PFOSconcentrations increasing, low concentration group was induced55.10%, theinhibition rates of middle and high concentrations were36.80%and53.76%. Thetrend of CAT activities in the gill tissue first increased with the stress time, and thendecreased and then increased, no significant dose-effect; the CAT activities of the lowconcentration group compared to the control group high63.98%, lower8.14%, high62.32%in1d,3d,15d respectively; CAT activities appeared significant time-effectand dose-effect in liver, the changes trend of CAT activities were first increased andthen reduced in the middle and high concentration group, the low concentration groupwas induction throughout the stress period. The changes trends of POD activities werefirst decreased and then increased in the gill, the middle concentration groupcompared to the control group decreased by34.02%, increased30.64%, increased55.99%in2d,7d,15d respectively; the activities of POD had time-effect anddose-effect in the liver significantly, first increased and then decreased in the highconcentration group and induced state in the low concentration group, POD activitiesdeclined with the exposing time and the elevating PFOS concentrations,3concentrations group of low, middle and high increased of51.75%, decreased17.61%and decreased42.37%compared to control in7d respectively. The changes of GSHcontent showed a wave of trend in the gill, induced by the overall effect in end the ofstress time, induced75.46%in low concentration group; there was a significantdose-effect relationship in the liver, GSH content decreased with the increasing ofPFOS concentration. The changes of GST activities were similar to the trends of GSHcontent in gills and liver, both showed a significant dose-effect and time-effect. The content of MDA showed increasing trend with the stress time in the two tissues,suggested that the two organizations had severe oxidative damage under PFOS stress.There was an index returned to the control level in recovering time in gill, and fourbiomarkers returned to the level of the control group in liver, which means therecovery speed of the liver was faster than gill; and SOD restored to the level of thecontrol group in the two tissues, suggested that SOD was more sensitive than otherindicators indicating changes of external environment.3、The lesions come out in gill and liver of red sea bream under0.1、1.0、2.0mg/L PFOS exposure, and the extent of lesions was deepen as the concentration ofPFOS solution and exposure time. In7d of PFOS exposure, the edema come out inthe top of gill in low concentration, the gill epithelial shedding appeared inintermediate concentration, there were severe gill fusion in high concentration, in15dstress, the severe gill fusion in high concentration, and gill lamellae were seriouslydamaged. Exposing7d in liver, A large number of cytoplasmic vacuoles and fatdroplets vacuolar appeared in low concentration, as exposure time, in15d, the celldeformed in each concentration and organization vacuoles emerged in highconcentration, that suggested liver subjected to severe tissue damage.4、There were significant changes in the expressions of CYP1A1, AHR2, GSTA1,GSTA2and GSTR1on the liver of red sea bream under exposing with0.1,1.0,2.0mg/L PFOS. And the expressions of CYP1A1, AHR2and GSTA1genes mRNA in theliver of red sea bream were similar under PFOS stress, the changes trends were firstdecreased and then increased and then decreased, three concentration groups were ininhibitory state at the end of exposure time, but there were differences the inhibitionlevel between the three concentrations, the relative expression levels of three genes inthe group of low concentrations of stress15d were0.67,0.93,0.72times than controlrespectively. The trend of GSTA2mRNA relative expression level was first increasedand then decreased, and the dose-effect was not obvious, the relative expressions oflow concentrations in2d and15d were3.60and1.14fold than control. The GSTR1mRNA expression changes trend was first increased and then decreased and thenincreased, the relative expressions of the low concentration group in1d,3d,15dwas1.48,0.66,1.74fold than control. There were still significant differences inrelative expressions of genes between dose groups and control in water purificationrecovery time. The result showed that the toxicity of PFOS on gene expression wasmore serious than on antioxidant enzymes... |
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