Dataset Information

Odorant receptor-based discovery of natural repellents of human lice.

ABSTRACT: The body louse, Pediculus humanus humanus, is an obligate blood-feeding ectoparasite and an important insect vector that mediates the transmission of diseases to humans. The analysis of the body louse genome revealed a drastic reduction of the chemosensory gene repertoires when compared to other insects, suggesting specific olfactory adaptations to host specialization and permanent parasitic lifestyle. Here, we present for the first time functional evidence for the role of odorant receptors (ORs) in this insect, with the objective to gain insight into the chemical ecology of this vector. We identified seven putative full-length ORs, in addition to the odorant receptor co-receptor (Orco), and expressed four of them in the Xenopus laevis oocytes system. When screened with a panel of ecologically-relevant odorants, PhumOR2 responded to a narrow set of compounds. At the behavior level, both head and body lice were repelled by the physiologically-active chemicals. This study presents the first evidence of the OR pathway being functional in lice and identifies PhumOR2 as a sensitive receptor of natural repellents that could be used to develop novel efficient molecules to control these insects.

SUBMITTER: Pelletier J

PROVIDER: S-EPMC4663167 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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Odorant receptor-based discovery of natural repellents of human lice.

Pelletier Julien J Xu Pingxi P Yoon Kyong S KS Clark John M JM Leal Walter S WS

Insect biochemistry and molecular biology 20151019

The body louse, Pediculus humanus humanus, is an obligate blood-feeding ectoparasite and an important insect vector that mediates the transmission of diseases to humans. The analysis of the body louse genome revealed a drastic reduction of the chemosensory gene repertoires when compared to other insects, suggesting specific olfactory adaptations to host specialization and permanent parasitic lifestyle. Here, we present for the first time functional evidence for the role of odorant receptors (ORs ...[more]

PMID: 26494014

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Project description:Blood-feeding insects such as mosquitoes are efficient vectors of human infectious diseases because they are strongly attracted by body heat, carbon dioxide and odours produced by their vertebrate hosts. Insect repellents containing DEET (N,N-diethyl-meta-toluamide) are highly effective, but the mechanism by which this chemical wards off biting insects remains controversial despite decades of investigation. DEET seems to act both at close range as a contact chemorepellent, by affecting insect gustatory receptors, and at long range, by affecting the olfactory system. Two opposing mechanisms for the observed behavioural effects of DEET in the gas phase have been proposed: that DEET interferes with the olfactory system to block host odour recognition and that DEET actively repels insects by activating olfactory neurons that elicit avoidance behaviour. Here we show that DEET functions as a modulator of the odour-gated ion channel formed by the insect odorant receptor complex. The functional insect odorant receptor complex consists of a common co-receptor, ORCO (ref. 15) (formerly called OR83B; ref. 16), and one or more variable odorant receptor subunits that confer odour selectivity. DEET acts on this complex to potentiate or inhibit odour-evoked activity or to inhibit odour-evoked suppression of spontaneous activity. This modulation depends on the specific odorant receptor and the concentration and identity of the odour ligand. We identify a single amino-acid polymorphism in the second transmembrane domain of receptor OR59B in a Drosophila melanogaster strain from Brazil that renders OR59B insensitive to inhibition by the odour ligand and modulation by DEET. Our data indicate that natural variation can modify the sensitivity of an odour-specific insect odorant receptor to odour ligands and DEET. Furthermore, they support the hypothesis that DEET acts as a molecular 'confusant' that scrambles the insect odour code, and provide a compelling explanation for the broad-spectrum efficacy of DEET against multiple insect species.

Dataset Information

Odorant receptor-based discovery of natural repellents of human lice.

Publications

Odorant receptor-based discovery of natural repellents of human lice.

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