Expression and characterization of two pesticide resistance-associated serine protease genes (NYD-tr and NYD-ch) from Culex pipiens pallens for metabolism of deltamethrin

Abstract

Two deltamethrin resistance-associated serine protease genes (NYD-tr and NYD-ch) were isolated from Culex pipiens pallens in our previous study. To study the function of NYD-Tr and NYD-Ch in the metabolism of deltamethrin, we constructed the recombinant plasmid pET32a(+)/NYD-tr and pET32a(+)/NYD-ch with a 6x histidine tag. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and Western blot analyses of the recombinant proteins revealed that the molecular weights of NYD-Tr and NYD-Ch are 42 and 50 kDa. Enzyme activity assay indicated that the recombinant NYD-Tr and NYD-Ch had the corresponding features of trypsin and chymotrypsin. Using BApNA as the substrate, NYD-Tr gave optimal activity between pH 9.0 and 10.5, while NYD-Ch was optimally active over the range of pH 8.0-11.0 using the S(Ala)(2)ProPhe-pNA as the substrate. Then, we investigated the metabolism of deltamethrin by NYD-Tr and NYD-Ch. Our results showed that NYD-Tr and NYD-Ch could hydrolyze deltamethrin. The acute oral toxicity of the metabolite to Wistar rats was much lower than deltamethrin.

Maternal inheritance of deltamethrin resistance in the salmon louse Lepeophtheirus salmonis (Krøyer) is associated with unique mtDNA haplotypes

“…In addition to esterases, certain serine proteases are capable of hydrolysing pyrethroids and have been found to be overexpressed in pyrethroid resistant insects [58,59]. Caligid sea lice are known to express significant levels of proteases that are involved in a number of key physiological processes including yolk utilisation in larvae, attachment to the host during infection, and digestion of the host’s skin tissues [60,61].…”

Venom allergen 5is Associated With Deltamethrin Resistance inCulex pipiens pallens(Diptera: Culicidae)

“…In addition, the SCP domain has also been proposed to be a Ca 2þ chelating serine protease. Serine proteases, such as trypsin and chymotrypsin, have been recognized as pyrethroid metabolism-associated genes (Yang et al 2008, Xiong et al 2014. Different trypsin-like serine proteinases may favor energy accumulation and amino acid provision, possibly mitigating the fitness costs associated with insecticide resistance in some strains of maize weevil (Silva et al 2010).…”

Mechanisms by which pesticides affect insect immunity

“…Pesticides that are known to be protease inhibitors potentially might also interfere with melanization, such as the extract from seeds of the tree legume, Acacia senega (Babu and Subrahmanyam, 2010). Conversely, insecticide resistant strains of the mosquito, Culex pipiens, possess high serine protease activity, expressing up to three times the levels of activities found in non-resistant strains (Gong et al, 2005;Yang et al, 2008). This over expression is probably related to a detoxification mechanism for the insecticide, but it likely has implications for immunity.…”