Effects Of BUVSs On The Antioxidant System And Toxic Effects Of The Corbicula Fluminea

UV stabilizers/filters are widely applied as ultraviolet absorbing compounds in industrial materials and personal care products to prevent degradation or protect human skin from harmful sunlight radiation.Among them,benzotriazole UV stabilizers(BUVSs)are most widely used compounds.Due to their ubiquitous use,bioaccumulation,and persistent in environment,they have been attracted widespread attention.However,data are limited for BUVSs toxicity,especially their toxiclogical effects and mechanisms on benthic animals.Among BUVSs,UV-234,UV-326,UV-329 and UV-P are most frequently detected in aquatic ecosystem.In this study,Corbicula fluminea(one of the dominant species of benthic animals)were exposed to either one dose of 0,0.1,1 or 10??g/L UV-234,UV-326,UV-329 and UV-P for 21 days.To analyze the toxic effects of BUVSs on the Corbicula fluminea and to clarify their mechanisms,the expression of heat shock protein-related genes,antioxidant enzymerelated genes,as well as antioxidant enzyme activities of the visceral mass were assessed.In addition,pathological changes and filtration rates were examined.The main conclusions are as follows:(1)The expressions of heat shock protein-related genes(including Hsp22,Hsp40,Hsp60,Hsp70 and Hsp90)were significantly up-regulated after exposure to UV-326,UV-329 and UV-P.Both Hsp60 and Hsp70 were significantly inhibited by UV-234,while Hsp22 levels were over-expressed in UV-234 treatments compared to other BUVSs groups.It is indicated that the exposure of 4 BUVSs could cause oxidative stress on the Corbicula fluminea.(2)After exposure to UV-326,UV-329 and UV-P,the expressions of(Cu/Zn)SOD and sod2 genes in the visceral mass of Corbicula fluminea were all up-regulated,while they were significantly inhibited by UV-234.In addition,the expression of gsts1,gstmi,Gpx-A and gsh-px genes in UV-326,UV-329 and UV-P groups were all up-regulated.These results showed that BUVSs may affect the function of antioxidant system of the Corbicula fluminea,and the effects of UV-234 might be different from that of other BUVSs;UV-234 might cause oxidative damage by inhibiting the expression of SODrelated genes,while the others might only induce the oxidative stress response of Corbicula fluminea and promote the metabolism of these compounds under the current exposure concentrations.(3)After exposure to BUVSs,SOD and CAT activities in Corbicula fluminea visceral mass were inhibited to varying degrees,while GST and MDA activities were significantly increased.These results indicated that BUVSs might affect the antioxidant system of the Corbicula fluminea and cause oxidative damage.(4)In exposure of BUVSs,the liver and pancreatic cells of Corbicula fluminea showed obvious luminal vacuoles,rupture of cell basement membrane,detachment of vesicular epithelial cells and abnormal cell division.In addition,the filtration rates of Corbicula fluminea were significantly increased.These results indicated that long-term exposure of BUVSs might cause histological damage and affect filtration rates of Corbicula fluminea.In summary,BUVSs interfere with the expression of antioxidant system related genes and enzyme activity of Corbicula fluminea,thus causing oxidative stress.As a result,BUVSs may cause histological damage and affect filtration rates of Corbicula fluminea.Furthermore,the toxiclogical effects and mechanisms of BUVSs may be related to the structure of these compounds;Corbicula fluminea are more sensitive to UV-234 than the other three BUVSs.