Zhang Jianqin, Li Daqi, Ge Pingting, Guo Yaping, Zhu Kun Yan, Ma Enbo, Zhang Jianzhen
Research Institute of Applied Biology, Shanxi University, Taiyuan, Shanxi, People's Republic of China.
Department of Entomology, Kansas State University, Manhattan, Kansas, United States of America.
PLoS One. 2014 Apr 10;9(4):e94809. doi: 10.1371/journal.pone.0094809. eCollection 2014.
Carboxylesterases (CarEs) belong to a superfamily of metabolic enzymes encoded by a number of genes and are widely distributed in microbes, plants and animals including insects. These enzymes play important roles in detoxification of insecticides and other xenobiotics, degradation of pheromones, regulation of neurodevelopment, and control of animal development. In this study, we characterized a total of 39 full-length cDNAs putatively encoding different CarEs from the migratory locust, Locusta migratoria, one of the most severe insect pests in many regions of the world, and evaluated the role of four CarE genes in insecticide detoxification. Our phylogenetic analysis grouped the 39 CarEs into five different clades including 20 CarEs in clade A, 3 in D, 13 in E, 1 in F and 2 in I. Four CarE genes (LmCesA3, LmCesA20, LmCesD1, LmCesE1), representing three different clades (A, D and E), were selected for further analyses. The transcripts of the four genes were detectable in all the developmental stages and tissues examined. LmCesA3 and LmCesE1 were mainly expressed in the fat bodies and Malpighian tubules, whereas LmCesA20 and LmCesD1 were predominately expressed in the muscles and hemolymph, respectively. The injection of double-stranded RNA (dsRNA) synthesized from each of the four CarE genes followed by the bioassay with each of four insecticides (chlorpyrifos, malathion, carbaryl and deltamethrin) increased the nymphal mortalities by 37.2 and 28.4% in response to malathion after LmCesA20 and LmCesE1 were silenced, respectively. Thus, we proposed that both LmCesA20 and LmCesE1 played an important role in detoxification of malathion in the locust. These results are expected to help researchers reveal the characteristics of diverse CarEs and assess the risk of insecticide resistance conferred by CarEs in the locust and other insect species.
羧酸酯酶（CarEs）属于由多个基因编码的代谢酶超家族，广泛分布于微生物、植物和包括昆虫在内的动物中。这些酶在杀虫剂和其他异生物质的解毒、信息素的降解、神经发育的调节以及动物发育的控制中发挥着重要作用。在本研究中，我们对总共39个推定编码来自飞蝗（Locusta migratoria）不同羧酸酯酶的全长cDNA进行了表征，飞蝗是世界许多地区最严重的害虫之一，并评估了四个羧酸酯酶基因在杀虫剂解毒中的作用。我们的系统发育分析将这39个羧酸酯酶分为五个不同的进化枝，包括进化枝A中的20个羧酸酯酶、进化枝D中的3个、进化枝E中的13个、进化枝F中的1个和进化枝I中的2个。代表三个不同进化枝（A、D和E）的四个羧酸酯酶基因（LmCesA3、LmCesA20、LmCesD1、LmCesE1）被选作进一步分析。在所有检测的发育阶段和组织中都可检测到这四个基因的转录本。LmCesA3和LmCesE1主要在脂肪体和马氏管中表达，而LmCesA20和LmCesD1分别主要在肌肉和血淋巴中表达。从四个羧酸酯酶基因中的每一个合成双链RNA（dsRNA）后，用四种杀虫剂（毒死蜱、马拉硫磷、西维因和溴氰菊酯）中的每一种进行生物测定，在LmCesA20和LmCesE1分别被沉默后，对马拉硫磷的若虫死亡率分别提高了37.2%和28.4%。因此，我们认为LmCesA20和LmCesE1在飞蝗对马拉硫磷的解毒中都发挥了重要作用。这些结果有望帮助研究人员揭示不同羧酸酯酶的特性，并评估羧酸酯酶赋予飞蝗和其他昆虫物种抗药性的风险。
