Department of Entomology, University of California Davis, Davis, California, United States of America.
PLoS One. 2010 Oct 22;5(10):e15403. doi: 10.1371/journal.pone.0015403.
The mosquito Anopheles funestus is one of the major malaria vector species in sub-Saharan Africa. Olfaction is essential in guiding mosquito behaviors. Odorant-binding proteins (OBPs) are highly expressed in insect olfactory tissues and involved in the first step of odorant reception. An improved understanding of the function of malaria mosquito OBPs may contribute to identifying new attractants/repellents and assist in the development of more efficient and environmentally friendly mosquito controlling strategies.
In this study, a large screening of over 50 ecologically significant odorant compounds led to the identification of 12 ligands that elicit significant electroantennographic (EAG) responses from An. funestus female antennae. To compare the absolute efficiency/potency of these chemicals, corrections were made for differences in volatility by determining the exact amount in a stimulus puff. Fourteen AfunOBP genes were cloned and their expression patterns were analyzed. AfunOBP1, 3, 7, 20 and 66 showed olfactory tissue specificity by reverse transcriptase PCR (RT-PCR). Quantitative real-time PCR (qRT-PCR) analysis showed that among olfactory-specific OBPs, AfunOBP1 and 3 are the most enriched OBPs in female antennae. Binding assay experiments showed that at pH 7, AfunOBP1 significantly binds to 2-undecanone, nonyl acetate, octyl acetate and 1-octen-3-ol but AfunOBP3, which shares 68% identify with AfunOBP1 at amino acid level, showed nearly no binding activity to the selected 12 EAG-active odorant compounds.
This work presents for the first time a study on the odorants and OBPs of the malaria vector mosquito An. funestus, which may provide insight into the An. funestus olfactory research, assist in a comparative study between major malaria mosquitoes An. gambiae and An. funestus olfactory system, and help developing new mosquito control strategies to reduce malaria transmission.
冈比亚按蚊是撒哈拉以南非洲地区主要的疟疾传播媒介之一。嗅觉在引导蚊子行为中起着至关重要的作用。气味结合蛋白（OBPs）在昆虫嗅觉组织中高度表达，参与气味受体的第一步。深入了解疟疾病媒蚊 OBPs 的功能可能有助于发现新的引诱剂/驱避剂，并有助于开发更有效和环保的蚊虫控制策略。
在这项研究中，对 50 多种具有生态意义的气味化合物进行了大规模筛选，从中鉴定出 12 种化合物，这些化合物能显著引发雌性冈比亚按蚊触角的电生理触角反应（EAG）。为了比较这些化学物质的绝对效率/效力，通过确定刺激脉冲中的精确量来校正挥发性差异。克隆了 14 个 AfunOBP 基因，并分析了它们的表达模式。通过反转录 PCR（RT-PCR）分析，AfunOBP1、3、7、20 和 66 显示出嗅觉组织特异性。实时定量 PCR（qRT-PCR）分析显示，在嗅觉特异性 OBPs 中，AfunOBP1 和 3 是雌触角中最丰富的 OBPs。结合实验表明，在 pH 值为 7 时，AfunOBP1 显著结合 2-十一酮、乙酸壬酯、乙酸辛酯和 1-辛烯-3-醇，但与 AfunOBP1 在氨基酸水平上具有 68%同源性的 AfunOBP3 对所选 12 种 EAG 活性气味化合物几乎没有结合活性。
本研究首次对疟疾传播媒介冈比亚按蚊的气味和 OBPs 进行了研究，这可能为冈比亚按蚊嗅觉研究提供深入了解，有助于比较主要疟疾蚊子冈比亚按蚊和按蚊的嗅觉系统，并有助于开发新的蚊虫控制策略，以减少疟疾传播。
