Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA.
Vanderbilt Institute for Global Health, Nashville, Tennessee, USA.
Sci Rep. 2017 Jan 9;7:40297. doi: 10.1038/srep40297.
The principal Afrotropical human malaria vector mosquito, Anopheles gambiae, remains a significant threat to global health. A critical component in the transmission of malaria is the ability of An. gambiae females to detect and respond to human-derived chemical kairomones in their search for blood meal hosts. The basis for host odor responses resides in olfactory receptor neurons (ORNs) that express chemoreceptors encoded by large gene families, including the odorant receptors (ORs) and the variant ionotropic receptors (IRs). While ORs have been the focus of extensive investigation, functional IR complexes and the chemical compounds that activate them have not been identified in An. gambiae. Here we report the transcriptional profiles and functional characterization of three An. gambiae IR (AgIr) complexes that specifically respond to amines or carboxylic acids - two classes of semiochemicals that have been implicated in mediating host-seeking by adult females but are not known to activate An. gambiae ORs (AgOrs). Our results suggest that AgIrs play critical roles in the detection and behavioral responses to important classes of host odors that are underrepresented in the AgOr chemical space.
主要的非洲人类疟疾传播媒介蚊子冈比亚按蚊仍然是全球健康的重大威胁。冈比亚按蚊传播疟疾的一个关键因素是雌性按蚊能够检测和响应人类来源的化学信息素，以寻找血液餐宿主。宿主气味反应的基础在于表达化学感受器的嗅觉受体神经元 (ORNs)，这些化学感受器由包括气味受体 (ORs) 和变体离子型受体 (IRs) 在内的大型基因家族编码。虽然 ORs 一直是广泛研究的焦点，但在冈比亚按蚊中尚未确定功能性 IR 复合物及其激活它们的化学化合物。在这里，我们报告了三种冈比亚按蚊 IR (AgIr) 复合物的转录谱和功能特征，它们专门对胺或羧酸类物质做出反应——这两类半化学物质已被认为在介导成年雌性的宿主寻找中起作用，但据报道不会激活冈比亚按蚊的 ORs (AgOrs)。我们的研究结果表明，AgIrs 在检测和行为反应中发挥关键作用，对重要的宿主气味类别的检测和行为反应不足，而这些气味类别的化学物质在 AgOr 化学空间中代表性不足。
