The glutathione S-transferases(GSTs)play important roles in detoxification of microcystins(MCs),but the responses of GSTs to MC-LR have not been well characterized in freshwater gastropod,Cipangopaludina cahayensis.In the present study,we cloned full-length cDNAs of mu-and pi-class GSTs(GSTM and GSTP)and partial cDNA of omega-class GST(GSTO),and determined the transcriptional responses of the three GST genes to different concentrations of MC-LR(0,1,10 and 100 lg/L)in C.cahayensis.The full-length cDNAs of GSTM and GSTP of C.cahayensis were 813 and 820 bp,containing an open reading frame(ORF)of 648 bp(encoding 215 amino acids)and 624 bp(encoding 207 amino acids),respectively.The mRNA expression of GSTM and GSTO significantly decreased after exposure to 10 lg/L MC-LR,and the mRNA expression of GSTP significantly decreased after100 lg/L MC-LR exposure.This might contribute to the detoxication of MCs in C.cahayensis,which is consistent with its sedentary life and filter-feeder status.The mRNA expression of the three GST isoforms in C.cahayensis could be used as biomarkers for water contamination.
