Insecticide-mediated up-regulation of cytochrome P450 genes in the red flour beetle (Tribolium castaneum).

Jianxiu Yao,Guonian Zhu,Yanping He,Kun Zhu,Da Xiao,Xiao Liang

doi:10.3390/ijms16012078

Abstract

Some cytochrome P450 (CYP) genes are known for their rapid up-regulation in response to insecticide exposures in insects. To date, however, limited information is available with respect to the relationships among the insecticide type, insecticide concentration, exposure duration and the up-regulated CYP genes. In this study, we examined the transcriptional response of eight selected CYP genes, including CYP4G7, CYP4Q4, CYP4BR3, CYP12H1, CYP6BK11, CYP9D4, CYP9Z5 and CYP345A1, to each of four insecticides in the red flour beetle, Tribolium castaneum. Reverse transcription quantitative PCR (RT-qPCR) revealed that CYP4G7 and CYP345A1 can be significantly up-regulated by cypermethrin (1.97- and 2.06-fold, respectively), permethrin (2.00- and 2.03-fold) and lambda-cyhalothrin (1.73- and 1.81-fold), whereas CYP4BR3 and CYP345A1 can be significantly up-regulated by imidacloprid (1.99- and 1.83-fold) when 20-day larvae were exposed to each of these insecticides at the concentration of LC20 for 24 h. Our studies also showed that similar levels of up-regulation can be achieved for CYP4G7, CYP4BR3 and CYP345A1 by cypermethrin, permethrin, lambda-cyhalothrin or imidacloprid with approximately one fourth of LC20 in 6 h. Our study demonstrated that up-regulation of these CYP genes was rapid and only required low concentrations of insecticides, and the up-regulation not only depended on the CYP genes but also the type of insecticides. Our results along with those from previous studies also indicated that there were no specific patterns for predicting the up-regulation of specific CYP gene families based on the insecticide classification.

Highlights

Cytochrome P450 (CYP) genes constitute one of the largest gene superfamilies, with representatives in all living organisms, including bacteria, fungi, plants, and animals [1]
Several genes in CYP6 and CYP9 gene families, which account for nearly half of all CYP genes in T. castaneum, have been implicated in the insecticide-mediated up-regulation and insecticide resistance [16]
CYP345A1 (Figure 4C) showed significant up-regulations compared to their corresponding controls at 6, 12 and 24 h. The levels of such up-regulations began to decrease and did not show significant differences at 48 h compared with those of their controls for both CYP4G7 and CYP345A1. These results indicated that the up-regulation of these two CYP genes by cypermethrin occurred at early stages of insecticide exposures

Summary

Introduction

Cytochrome P450 (CYP) genes constitute one of the largest gene superfamilies, with representatives in all living organisms, including bacteria, fungi, plants, and animals [1]. CYP enzymes are commonly involved in the metabolism of either endogenous or exogenous compounds. CYP-mediated detoxification is an important resistance mechanism that can cause a significantly high level of resistance to many insecticides in insect populations [4]. CYP genes are involved in insect growth, development and nutrition [5]. It is believed that the diverse functions of cytochrome P450s are primarily due to the diversity of CYP genes [6]. Thousands of CYP genes in total have been identified in insects [7], and the number is still growing rapidly as more insect genomes are sequenced [8]

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