Bioaccumulation and function analysis of glutathione S-transferase isoforms in Manila clam Ruditapes philippinarum exposed to different kinds of PAHs

This study analyzed the function of different glutathione S-transferase (GST) isoforms and detoxification metabolism responses in Manila clam,Ruditapes philippinarum,exposed to 4 kinds of polycyclic aromatic hydrocarbons (PAHs) single,and their mixtures for 15 days un-der laboratory conditions.13 kinds of GSTs in R.philippinarum were classified,and the re-sults of tissue distribution indicated that 12 kinds of GSTs (except GST sigma 3) expressed most in digestive glands.We detected the mRNA expression levels of aryl hydrocarbon re-ceptor signaling pathway,and detoxification system in digestive glands of clams exposed to benzoa]pyrene (BaP),chrysene (CHR),benzoa]anthracene (BaA),benzob]fluoranthene(BbF),and BaP + CHR + BaA + BbF,respectively.Among these genes,we selected GST-sigma,GST-omega and GST-pi as potential indicators to BaP;GST-sigma,GST-A and GST-rho to CHR;GST-pi,GST-sigma,GST-A,GST-rho and GST-microsomal to BaA;GST-theta and GST-mu to BbF;while GST-pi and GST-mu to the mixture of BaP,CHR,BaA and BbF.Additionally,the bioaccu-mulation of PAHs in tissues increased remarkably over time,and showed an obvious dose-effect.Under the same concentration,the bioaccumulation in single exposure group was higher than that in mixture group,and the bioaccumulation of PAHs in tissues with dif-ferent concentrations of stress was irregular.The results revealed the metabolic differences and bioaccumulation rules in clams exposed to four kinds of PA-Hs,and provided more valu-able information for the PAHs risk assessment.