Chitosan/DsiRNA nanoparticle targeting identifies AgCad1 cadherin in Anopheles gambiae larvae as an in vivo receptor of Cry11Ba toxin of Bacillus thuringiensis subsp. jegathesan

The insecticidal Cry4Ba and Cry11Aa crystal proteins from Bacillus thuringiensis subsp. israelensis (Bti) are highly toxic to Ae. aegypti larvae. The glycosylphosphatidylinositol (GPI)-anchored APN was identified as an important membrane-bound receptor for multiple Cry toxins in numerous Lepidoptera, Coleoptera, and Diptera insects. However, there is no direct molecular evidence to link APN of Ae. aegypti to Bti toxicity in vivo. In this study, two Cry4Ba/Cry11Aa-binding Ae. aegypti GPI-APN isoforms (AeAPN1 and AeAPN2) were individually knocked-out using CRISPR/Cas9 mutagenesis, and the AeAPN1/AeAPN2 double-mutant homozygous strain was generated using the reverse genetics approach. ELISA assays showed that the high binding affinity of Cry4Ba and Cry11Aa protoxins to the midgut brush border membrane vesicles (BBMVs) from these APN knockouts was similar to the background from the wild-type (WT) strain. Likewise, the bioassay results showed that neither the single knockout of AeAPN1 or AeAPN2, nor the simultaneous disruption of AeAPN1 and AeAPN2 resulted in significant changes in susceptibility of Ae. aegypti larvae to Cry4Ba and Cry11Aa toxins. Accordingly, our results suggest that AeAPN1 and AeAPN2 may not mediate Bti Cry4Ba and Cry11Aa toxicity in Ae. aegypti larvae as their binding proteins.

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Transcriptional regulation of Bacillus thuringiensis subsp. israelensis mosquito larvicidal crystal protein gene cryIVA.

Journal of Bacteriology ◽

10.1128/jb.175.9.2750-2753.1993 ◽

1993 ◽

Vol 175 (9) ◽

pp. 2750-2753 ◽

Cited By ~ 24

Author(s):

H Yoshisue ◽

T Fukada ◽

K Yoshida ◽

K Sen ◽

S Kurosawa ◽

...

Keyword(s):

Transcriptional Regulation ◽

Bacillus Thuringiensis ◽

Protein Gene ◽

Crystal Protein ◽

Bacillus Thuringiensis Subsp

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Compensatory mechanisms in resistant Anopheles gambiae AcerKis and KdrKis neurons modulate insecticide-based mosquito control

Communications Biology ◽

10.1038/s42003-021-02192-0 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Stéphane Perrier ◽

Eléonore Moreau ◽

Caroline Deshayes ◽

Marine El-Adouzi ◽

Delphine Goven ◽

...

Keyword(s):

Sodium Channel ◽

Anopheles Gambiae ◽

Calcium Concentration ◽

Mosquito Control ◽

Point Mutations ◽

Resting Membrane Potential ◽

Compensatory Mechanisms ◽

Pyrethroid Insecticides

AbstractIn the malaria vector Anopheles gambiae, two point mutations in the acetylcholinesterase (ace-1R) and the sodium channel (kdrR) genes confer resistance to organophosphate/carbamate and pyrethroid insecticides, respectively. The mechanisms of compensation that recover the functional alterations associated with these mutations and their role in the modulation of insecticide efficacy are unknown. Using multidisciplinary approaches adapted to neurons isolated from resistant Anopheles gambiae AcerKis and KdrKis strains together with larval bioassays, we demonstrate that nAChRs, and the intracellular calcium concentration represent the key components of an adaptation strategy ensuring neuronal functions maintenance. In AcerKis neurons, the increased effect of acetylcholine related to the reduced acetylcholinesterase activity is compensated by expressing higher density of nAChRs permeable to calcium. In KdrKis neurons, changes in the biophysical properties of the L1014F mutant sodium channel, leading to enhance overlap between activation and inactivation relationships, diminish the resting membrane potential and reduce the fraction of calcium channels available involved in acetylcholine release. Together with the lower intracellular basal calcium concentration observed, these factors increase nAChRs sensitivity to maintain the effect of low concentration of acetylcholine. These results explain the opposite effects of the insecticide clothianidin observed in AcerKis and KdrKis neurons in vitro and in vivo.

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