Abstract:An abridged carboxylesterase E4 (CbE E4) gene was cloned from the peach-potato aphid, Myzus persicae, by reverse transcription-PCR and subcloned into the expression vector pET28b. The abridged CbE E4 gene was successfully expressed in E. coli BL21 (DE3). The recombinant CbE E4 hydrolyzed beta-naphthyl acetate and Carbaryl by 64% within 2.5 h, Malathion by 80% within 1.25 h. However, the hydrolysis of other pesticides (Dichlorovos, Parathion, Pirimicarb and Deltamethrin) was not detected.
“…Although a number of bacteria with malathion hydrolase activity have been investigated (Foster and Bia 2004; Hashmi et al 2004; Goda et al 2010; Baljinder et al 2012), recombinant carboxylesterases for malathion degradation have not been reported in Alicyclobacillus . The enzyme also shows stronger malathion degradation than carboxylesterase E4 from peach-potato aphid (Lan et al 2005). Fig.…”
A carboxylesterase gene from thermophilic bacterium, Alicyclobacillus tengchongensis, was cloned and expressed in Escherichia coli BL21 (DE3). The gene coded for a 513 amino acid protein with a calculated molecular mass of 57.82 kDa. The deduced amino acid sequence had structural features highly conserved among serine hydrolases, including Ser204, Glu325, and His415 as a catalytic triad, as well as type-B carboxylesterase serine active site (FGGDPENITIGGQSAG) and type-B carboxylesterase signature 2 (EDCLYLNIWTP). The purified enzyme exhibited optimum activity with β-naphthyl acetate at 60 °C and pH 7 as well as stability at 25 °C and pH 7. One unit of the enzyme hydrolyzed 5 mg malathion l−1 by 50 % within 25 min and 89 % within 100 min. The enzyme strongly degraded malathion and has a potential use for the detoxification of malathion residues.
“…Although a number of bacteria with malathion hydrolase activity have been investigated (Foster and Bia 2004; Hashmi et al 2004; Goda et al 2010; Baljinder et al 2012), recombinant carboxylesterases for malathion degradation have not been reported in Alicyclobacillus . The enzyme also shows stronger malathion degradation than carboxylesterase E4 from peach-potato aphid (Lan et al 2005). Fig.…”
A carboxylesterase gene from thermophilic bacterium, Alicyclobacillus tengchongensis, was cloned and expressed in Escherichia coli BL21 (DE3). The gene coded for a 513 amino acid protein with a calculated molecular mass of 57.82 kDa. The deduced amino acid sequence had structural features highly conserved among serine hydrolases, including Ser204, Glu325, and His415 as a catalytic triad, as well as type-B carboxylesterase serine active site (FGGDPENITIGGQSAG) and type-B carboxylesterase signature 2 (EDCLYLNIWTP). The purified enzyme exhibited optimum activity with β-naphthyl acetate at 60 °C and pH 7 as well as stability at 25 °C and pH 7. One unit of the enzyme hydrolyzed 5 mg malathion l−1 by 50 % within 25 min and 89 % within 100 min. The enzyme strongly degraded malathion and has a potential use for the detoxification of malathion residues.
“…In some cases, increased esterase activity has been shown to be responsible for OP resistance as a result of overexpression mediated by gene amplification, as in the OP‐resistant Myzus persicae , in which overproduction of esterase E4 or FE4 through gene amplification was identified (Lan et al ., ). This led us to further investigate the gene copy number of BdCarE4 and BdCarE6 in both the MR and MS strains.…”
Section: Discussionmentioning
confidence: 99%
“…As esterase mutation usually confers an increase in OP hydrolytic activity, along with a reduction in CarE activity (Cui et al, 2011), this result was consistent with our finding of enhanced CarE activity in the MR strain and led us to further investigate the up-regulation and amplification of these two genes. In some cases, increased esterase activity has been shown to be responsible for OP resistance as a result of overexpression mediated by gene amplification, as in the OP-resistant Myzus persicae, in which overproduction of esterase E4 or FE4 through gene amplification was identified (Lan et al, 2005). This led us to further investigate the gene copy number of BdCarE4 and BdCarE6 in both the MR and MS strains.…”
Esterase has been reported to be involved in malathion resistance in the oriental fruit fly, Bactrocera dorsalis (Hendel). However, the underlying molecular mechanism of the esterase-mediated resistance remains largely unknown in this species. Here, with the use of a strain selected for malathion resistance in the laboratory (MR), we found that two overexpressed α-esterase genes, namely BdCarE4 and BdCarE6, predominant in the adult midgut and fat body, function in conferring malathion resistance in B. dorsalis. Notably, these two genes were found to be mostly close to the esterase E3, which are usually implicated in detoxifying organophosphate insecticides. The transcript levels of BdCarE4 and BdCarE6 were investigated and compared between the MR and a susceptible (MS) strain of B. dorsalis. Both genes were significantly up-regulated in the MR strain, which was consistent with the enhanced esterase activity in the MR strain. However, no changes in either the coding sequence or gene copy number were observed between the two strains. Subsequently, heterologous expression combined with cytotoxicity assay in Sf9 cells demonstrated that BdCarE4 and BdCarE6 can probably detoxify malathion. Furthermore, RNA interference-mediated knockdown of each of these two genes significantly increased malathion susceptibility in the MR strain adults. In conclusion, these results expand our molecular understanding of the important role of α-esterases during the development of resistance to organophosphorous insecticides in B. dorsalis.
“…It can be concluded that both compounds even at high concentration (150 nM) do not significantly increase mortality compared to the reference. Aphids are known as formidable pests capable of infesting various host plants (Blackman & Eastop 1994) and of resisting to herbicides (Lan et al 2005), parasites (Oliver et al 2003) and secondary metabolites (Francis et al 2005).…”
Oxylipins are oxygenated fatty acids and their derivatives that play key roles in response to stress. They are widespread in many organisms including mammals or plants but are unknown in arthropods. In this study, we identified oxylipins in Myzys persicae Sulzer aphids reared on Vicia faba L. plants. Further experiments based on: (i) Radiolabelled substrate incubation with aphid extracts, and (ii) rearing of aphids on an artificial diet revealed that aphids were unable to synthesize oxylipins. As the V. faba total leaf oxylipin profile differs from the aphid one, it was assessed whether: (i) Aphids are able to transform leaf oxylipins, or (ii) phloem sap (ingested by aphids when feeding on plants) contains oxylipins different from total leaf ones. Phloem exudates analysis revealed, for the first time, that it contains oxylipins that are different from total leaf ones. These oxylipins are further ingested by aphids.
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