Identification of carboxylesterase genes associated with pyrethroid resistance in the malaria vector Anopheles sinensis (Diptera: Culicidae).

Abstract

Carboxylesterases (CCEs) are one of three large detoxification enzyme families. Some CCEs are active on synthetic insecticides with ester structures. Anopheles sinensis is an important malaria vector in eastern Asia. This study identified and characterized the CCE genes in the A. sinensis genome and determined CCE genes associated with pyrethroid resistance using RNA sequencing (RNA-seq) and quantitative reverse transcription - polymerase chain reaction (qRT-PCR), in A. sinensis from Anhui, Chongqing, and Yunnan in China. Fifty-seven putative CCEs were identified and placed into three classes, 12 subfamilies and 14 clades through phylogenetic and homology analyses. Exon sizes ranged from 31 to 4317 bp, with 49 CCEs having two to five exons and eight having six to 11 exons. A total of 183 introns were recognized with sizes ranging from 31 to 4317 bp. The 57 CCEs were located on 14 scaffolds, with 70% located on four scaffolds. The alpha-esterase subfamily was significantly expanded compared with that of Anopheles gambiae. In a pyrethroid-resistant strain, RNA-seq detected five upregulated CCE genes and qRT-PCR detected 12 upregulated CCE genes. The α-esterase 10 (AsAe10) and acetylcholinesterase 1 (AsAce1) genes were the main CCE genes associated with pyrethroid resistance. This information will be useful for further study of the CCE gene family and pyrethroid resistance mechanisms mediated by CCEs. © 2017 Society of Chemical Industry.