Hughes DT et al. (2010), Odorant receptor from the southern house mosqui...

XB-ART-41753

J Chem Ecol 2010 Aug 01;368:797-800. doi: 10.1007/s10886-010-9828-9.

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Odorant receptor from the southern house mosquito narrowly tuned to the oviposition attractant skatole.

Hughes DT , Pelletier J , Luetje CW , Leal WS .

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Oviposition attractants are environmental cues that allow Culex gravid female mosquitoes to locate suitable sites for egg-laying and, therefore, may be exploited for environmentally friendly strategies for controlling mosquito populations. Naturally occurring skatole has been identified as an oviposition attractant for the Southern House mosquito, Culex quinquefasciatus. Previously, we identified in Cx. quinquefasciatus female antennae an olfactory receptor neuron (ORN) highly sensitive to skatole and an odorant-binding protein involved in the detection of this semiochemical. Here, we describe the characterization of an odorant receptor (OR), CquiOR10, which is narrowly tuned to skatole when expressed in the Xenopus oocyte system. Odorant-induced response profiles generated by heterologously expressed CquiOR10 suggest that this OR is expressed in the mosquito ORN sensitive to skatole. However, geranylacetone, which stimulates the antennal ORN, was not detected by CquiOR10-expressing oocytes, thus raising interesting questions about reception of oviposition attractants in mosquitoes.

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Fig. 1. Odorant receptor CquiOR10 is highly sensitive to skatole (3-methylindole). a Oocytes expressing CquiOR10 + CquiOR7 were challenged with a panel of odorant compounds. Each odorant was applied at a concentration of 10 μM for 20 sec with 10 min washes between applications. All responses are normalized to the response of the same oocyte to 10 μM indole (mean ± SEM, N = 4–5). b Oocytes expressing CquiOR10 + CquiOR7 were challenged with a range of concentrations of 3-methylindole (top trace), indole (middle trace) or 2-methylphenol (bottom trace). Each odorant was applied for 20 sec with 5–20 min washes between applications. Note different scales: from top to bottom 500, 200 and 400 nA. c Oocytes expressing CquiOR10 + CquiOR7 were challenged with a range of concentrations of 3-methylindole, indole, and 2-methylphenol. Responses were normalized to the response of each oocyte to 10 μM indole and are presented as mean ± sem (N = 3–5 for each odorant tested). Data were fit to the equation: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\hbox{I}} = {{\hbox{I}}_{{ \max }}}/\left( {{1} + {{\left( {{\hbox{E}}{{\hbox{C}}_{{5}0}}/{\hbox{X}}} \right)}^{\rm{n}}}} \right) $$\end{document} where I represents the current response at a given concentration of odorant (X), Imax is the maximal response, EC50 is the concentration of odorant yielding a half maximal response, and n is the apparent Hill coefficient. Derived values are: 3-methylindole, EC50 = 90 ± 17 nM, N = 1.0 ± 0.1; indole, EC50 = 2.4 ± 0.3 μM, N = 1.1 ± 0.2; 2-methylphenol, EC50 = 41 ± 7 μM, N = 1.0 ± 0.1

References [+] :

Barbosa, Culex mosquitoes (Diptera: Culicidae) egg laying in traps loaded with Bacillus thuringiensis variety israelensis and baited with skatole. 2010, Pubmed