Xu Pingxi, Choo Young-Moo, Chen Zhou, Zeng Fangfang, Tan Kaiming, Chen Tsung-Yu, Cornel Anthony J, Liu Nannan, Leal Walter S
Department of Molecular and Cellular Biology, University of California-Davis, Davis, CA 95616, USA.
Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36489, USA.
iScience. 2019 Sep 27;19:25-38. doi: 10.1016/j.isci.2019.07.008. Epub 2019 Jul 12.
How chemical signals are integrated at the peripheral sensory system of insects is still an enigma. Here we show that when coexpressed with Orco in Xenopus oocytes, an odorant receptor from the southern house mosquito, CquiOR32, generated inward (regular) currents when challenged with cyclohexanone and methyl salicylate, whereas eucalyptol and fenchone elicited inhibitory (upward) currents. Responses of CquiOR32-CquiOrco-expressing oocytes to odorants were reduced in a dose-dependent fashion by coapplication of inhibitors. This intrareceptor inhibition was also manifested in vivo in fruit flies expressing the mosquito receptor CquiOR32, as well in neurons on the antennae of the southern house mosquito. Likewise, an orthologue from the yellow fever mosquito, AaegOR71, showed intrareceptor inhibition in the Xenopus oocyte recording system and corresponding inhibition in antennal neurons. Inhibition was also manifested in mosquito behavior. Blood-seeking females were repelled by methyl salicylate, but repellence was significantly reduced when methyl salicylate was coapplied with eucalyptol.
化学信号在昆虫外周感觉系统中是如何整合的仍然是一个谜。在这里我们表明，当与爪蟾卵母细胞中的Orco共表达时，南方家蚊的一种气味受体CquiOR32，在用环己酮和水杨酸甲酯刺激时会产生内向（正常）电流，而桉叶油素和小茴香酮会引发抑制性（向上）电流。通过共同应用抑制剂，表达CquiOR32-CquiOrco的卵母细胞对气味剂的反应以剂量依赖的方式降低。这种受体内抑制在表达蚊子受体CquiOR32的果蝇体内也有体现，在南方家蚊触角上的神经元中也是如此。同样，来自黄热病蚊子的一个同源物AaegOR71，在爪蟾卵母细胞记录系统中表现出受体内抑制，并在触角神经元中表现出相应的抑制。抑制也体现在蚊子的行为中。寻找血液的雌性蚊子会被水杨酸甲酯驱避，但当水杨酸甲酯与桉叶油素共同应用时，驱避作用会显著降低。
