Pyrethroids are ubiquitously present in environmental media and threaten both the ecosystem and human health. To explore effective ways to remove pyrethroids from the environment, an odorant binding protein (OBP) with affinity for various pyrethroids was investigated. Initially, the target OBP, Spodoptera littoralis pheromone binding protein 1 (SlitPBP1), underwent redesign to enhance its affinity for pyrethroids. The modified SlitPBP1E97ND106E demonstrated a substantially increased affinity for deltamethrin (DeltaM), with a dissociation constant of 0.77 ± 0.17 μM. The affinity of SlitPBP1E97ND106E for other pyrethroids also increased to varying extents. Consequently, SlitPBP1E97ND106E displayed a markedly enhanced capability to adsorb and remove pyrethroids. When exposed to free SlitPBP1E97ND106E in solution, the reduction in DeltaM surged from 16.78 ± 0.32% to 97.51 ± 0.56%. SlitPBP1E97ND106E was immobilized by coupling the protein to Ni 2+ -NTA agarose resin. Liquid chromatography results attested to the superior efficacy of immobilized SlitPBP1E97ND106E in removing pyrethroids, especially DeltaM. No significant differences in pyrethroid removal were detected across various water samples. Our findings introduce a potent tool for pyrethroid removal. A wider range of OBPs can similarly be optimized and applied to remove organic pollutants , including but not limited to pesticides.
Kai Tian,Jing Feng,Jiang Zhu,Jiagao Cheng,Mei Li,Xinghui Qiu
The cotton bollworm , Helicoverpa armigera , is a polyphagous pest threatening many economically important crops worldwide. Until recently, synthetic pyrethroids remain in wide use for controlling pest insects including the cotton bollworm. Understanding the metabolic mechanism of pyrethroids in a given pest can provide significant implication for a smart choice of insecticides, and such information is useful for the development of novel selective and safe insecticides. In this study, we used complexes of recombinant H. armigera cytochrome P450 CYP9A and NADPH-dependent cytochrome P450 reductase to investigate the capacity of three CYP9A paralogs in the transformation of seven structurally different pyrethroids by metabolism assays. The results showed that the three paralogous CYP9As were able to metabolize multiple pyrethroids. Interestingly, all the three CYP9As transformed pyrethrin-resembling pyrethroids (e.g. bioallethrin) more efficiently than the heavily modified ones (e.g. bifenthrin). These findings suggest that herbivorous insects can cope with synthetic insecticides using their physiological systems that initially evolved to survive exposure to the defensive chemicals in their host plants, adding support to the pre-adaptation hypothesis.
Populations of many amphibian species are declining worldwide in part because of pesticide contamination. As a surface water contaminant, α-cypermethrin may have severe ecological impacts on amphibians. Here, we examined the acute toxicity of α-cypermethrin enantiomers to dark-spotted frog Rana nigromaculata tadpoles at 24, 48, 72 and 96 h, finding that the tadpoles were indeed sensitive to α-cypermethrin. The (S)-(1R, 3R)-enantiomer was approximately 29 times more toxic than the (R)-(1S, 3S)-enantiomer at 96 h. A significant delayed growth in R. nigromaculata tadpoles after exposure to 0.5 µg L −1 of S-(1R, 3R)-cypermethrin was observed. Additionally, increased superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST) and malondialdehyde (MDA) levels indicate the presence of oxidative stress in the tadpoles. Further, tadpoles exposed to sublethal concentrations of α-cypermethrin enantiomers exhibited enantioselective growth and oxidative damage. Bioaccumulation experiments showed that the tadpoles could rapidly accumulate α-cypermethrin. The (R)-(1S, 3S)-enantiomer was preferentially accumulated over the (S)-(1R, 3R)-enantiomer, and it was also eliminated more quickly, as evidenced in the subsequent depuration experiments.
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