Molecular Cloning and Xenobiotic Induction of Seven Novel Cytochrome P450 Monooxygenases in Aedes albopictus

Abstract

Cytochrome P450 monooxygenase (P450) is a superfamily of enzymes that is important in metabolism of endogenous and exogenous compounds. In insects, these enzymes confer resistance to insecticides through its metabolic activities. Members of P450 from family 6 in insects are known to play a role in such function. In this study, we have isolated seven novel family 6 P450 from Aedes albopictus (Skuse) (Diptera: Culicidae), a vector of dengue and chikungunya fever. Induction profile of these seven genes was studied using several insecticides and xenobiotics. It was found that deltamethrin and permethrin did not induce expression of any genes. Another insecticide, temephos, inhibited expression of CYP6P15 for fivefold and twofold for CYP6N29 , CYP6Y7 , and CYP6Z18 . In addition, copper II sulfate induced expression of CYP6M17 and CYP6N28 for up to sixfold. Benzothiazole (BZT), a tire leachate induced the expression of CYP6M17 by fourfold, CYP6N28 by sevenfold, but inhibited the expression of CYP6P15 for threefold and CYP6Y7 for twofold. Meanwhile, piperonyl butoxide (PBO) induced the expression CYP6N28 (twofold), while it inhibited the expression of CYP6P15 (fivefold) and CYP6Y7 (twofold). Remarkably, all seven genes were induced two- to eightfold by acetone in larval stage, but not adult stage. Expression of CYP6N28 was twofold higher, while expression of CYP6P15 was 15-fold lower in adult than larva. The other five P450s were not differentially expressed between the larvae and adult. This finding showed that acetone can be a good inducer of P450 in Ae. albopictus . On the other hand, temephos can act as good suppressor of P450, which may affect its own bioefficacy because it needs to be bioactivated by P450. To the best of our knowledge, this is the first report on acetone-inducible P450 in insects. Further study is needed to characterize the mechanisms involved in acetone induction in P450 .

Epigenetic alterations and decreasing insecticide sensitivity of the Asian tiger mosquito Aedes albopictus

“…For that reason the effective solvent concentration of 1% acetone was considered to be safe for the experiments of this study, although this value exceeds the recommended solvent concentration of 0.1 ml L À 1 ( ¼0.1% (OECD, 2002)). A new study (Chan et al, 2014), however, revealed acetone driven induction of the cytochrome P450 monooxygenase system at low concentrations (0.4%) in larval A. albopictus. In the study of Vandegehuchte et al (2010) genistein and vinclozolin were also applied in aqueous exposures to Daphnia magna based on the solvent dimethyl sulphoxide (DMSO) and no effects on the DNA methylation level of D. magna were detected at concentrations of 0.0176% and 0.05% DMSO.…”

The effect of insecticide synergist treatment on genome-wide gene expression in a polyphagous pest

“…As hypothesized by Chan et al . 81 , it might be a compensation strategy for an enzyme to be upregulated upon contact with an inhibitor in order to minimize the effect of reduced enzyme activity. In general, several studies have shown that xenobiotics are able to induce expression of arthropod P450s 11 , 44 , 45 , 48 , 77 , 83 – 86 .…”

Characterization of pyrethroid resistance in the western corn rootwormDiabrotica virgifera virgiferaLeConte

“…For example, DEF was shown to not inhibit carboxylamidase in Spodoptera frugiperda (Smith) larvae (Yu and Nguyen 1998) and to act as an inhibitor of P450s in Blatella germanica (L.) (Sanchez-Arroyo et al 2001). Furthermore, PBO was shown to act as an inhibitor of esterases , López-Soler et al 2011 and to induce expression of several P450s, including those from the CYP6 family usually implicated in conferring resistance in insect pests , Willoughby et al 2007, Chiu et al 2008, Müller et al 2008, Zhu et al 2010, Chan et al 2014, Zimmer et al 2017).…”

“…Higher PBO synergism provided in the susceptible population during bifenthrin bioassays suggests a more pronounced enzyme inhibition in that population, which was previously observed in synergism bioassays performed with other insect species (Huang et al 2010, Malek Mohamadi et al 2010). However, it is possible that while some enzymes were inhibited in both populations tested, other enzymes could have been somewhat induced in the lab selected population following PBO treatment as a compensation strategy to minimize the effect of reduced enzyme activity (Chan et al 2014, Snoeck et al 2017. For example, Zimmer et al, (2017) showed that exposing a pyrethroid-resistant population of whitefly Bemisia tabaci (Gennadius) to PBO+cypermethrin mixture increased its susceptibility to cypermethrin (lower the LC50 values), but also upregulated the expression of the P450 gene Cyp6cm1.…”