Cloning and Expression of Two Carboxylesterases, and Their Activity Modulation in Chinese Mitten crab Eriocheir sinensis under Pesticide Exposer

Carboxylesterases (CXEs) belong to a family of multifunctional enzymes. They metabolize drugs, environmental toxicants, and carcinogens, and inhibit bacterial pathogenesis. In this study, the full-length cDNAs of ES-CXE3 (2,444 bp) and ES -CXE4 (2,385 bp) were cloned from the Chinese mitten crab, Eriocheir sinensis. Sequence analysis showed that both ES-CXE sequences contained the catalytic triplet structure characteristic of the CXEs superfamily. Alignment and phylogenetic analyses revealed that the two ES-CXEs are highly similar to those of other crustaceans. Tissue specific-expression analysis showed that both ES-CXEs were highly expressed in the hepatopancreas. Real-time fluorescence quantitative PCR showed that the maximum expression levels of the ES-CXE3 and ES-CXE4 genes in the hepatopancreas of E. sinensis exposed to low doses of beta-cypermethrin, avermectin and trichlorfon were 10x, 8x, 6x and 600x, 110x, 250x higher than relative to those of the control group, respectively, and that enzyme activities steadily increased and were significantly higher than that of the control group. Therefore, treatment with these insecticides may induce the expression of both ES-CXEs as well as changes in the activities of carboxylesterase family genes. Our results suggest that ES-CXEs might play vital roles for insecticide detoxification in E. sinensis