Cloning and the sequence analysis of the fish glutathione transferase Pi gene
鱼类谷胱甘肽转移酶基因cDNA克隆及其序列分析

Using RT-PCR method,the glutathione transferase Pi cDNAs were cloned from Cyprinus carpio,Hy-pophthalmichthys molitrix,and Carassius auratus.The open reading frames(ORFs) from the 3 fishes were 627 bp long(encoding for 208 amino acids) with the initial code ATG and the terminal code TGA.The sequence similarity was 50% between fish and mammals,33% between fish and amphibian,and 15% between fish and arthropoda,respectively.The sequence similarity was big among fishes,and the average value of the 4 cyprinids was about 85%.Phylogenetic tree was constructed for 13 species based on GST Pi amino acid sequences using MP(Maximum Parsimony) method.Two major clusters were recognized:cluster one consisted of Mammals(bootstrap 100) and cluster two consisted of fishes(bootstrap 93) .Based on the sequences analyses of N/C domain of GST Pi,we proposed the detoxification mechanism of freshwater fishes that were thought to have stronger tolerance to microcystins.