Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan; Department of Biological Production, Faculty of Agriculture, Tokyo University of Agriculture and Technology (TUAT), Fuchu, Tokyo 183-8509, Japan.
Research Center for Advanced Science and Technology, The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan; Faculty of Agriculture, Tokyo University of Agriculture, Atsugi, Kanagawa 243-0034, Japan.
J Insect Physiol. 2020 Feb-Mar;121:104018. doi: 10.1016/j.jinsphys.2020.104018. Epub 2020 Jan 24.
Bombykol (EZ) is the single component of the female sex pheromone in the silkmoth Bombyx mori. EZ alone evokes full courtship behaviors from conspecific males; however, its geometric isomer (EE) was consistently detected in the pheromone glands (PG) of 16 B. mori strains and a field population of the wild silkmoth Bombyx mandarina, which also uses EZ as the single pheromone component. We investigated the pheromonal activities of EE using a commercial hybrid strain of B. mori, Kinshu × Showa. The behavioral assay demonstrated that a 10-10-fold higher dose of EE than EZ was able to elicit behavioral responses from males. To elucidate whether the trace contaminant of EZ in the EE standard is responsible for these responses, we examined the responses of male antennae to EE using a gas chromatograph-electroantennographic detector system (GC-EAD). The EE, at high doses elicited marginal responses from the male antennae. We next examined antennal and behavioral responses of B. mori whose BmOR1 gene, which is responsible for the reception of bombykol, was knocked out. The knockout of BmOR1 resulted in the complete loss of antennal and behavioral responses to EE and EZ, demonstrating that if EE itself is active, it induces these responses via the incidental stimulation of BmOR1, not via the stimulation of EE-specific receptors. The existence of EE in the PG of B. mori and B. mandarina is discussed from the viewpoints of pheromone biosynthesis and the evolution of pheromone communication systems.
Bombykol（EZ）是家蚕 Bombyx mori 雌性信息素的单一成分。EZ 本身就能引起同种雄性的全套求偶行为；然而，其几何异构体（EE）一直在家蚕 16 个品系和野桑蚕 Bombyx mandarina 的信息素腺体（PG）中被检测到，后者也将 EZ 作为单一的信息素成分使用。我们使用商业杂交品种 Kinshu×Showa 家蚕研究了 EE 的信息素活性。行为测定表明，EE 的剂量比 EZ 高 10-10 倍就能引起雄性的行为反应。为了阐明 EE 标准中 EZ 的痕量污染物是否是这些反应的原因，我们使用气相色谱-触角电位测定系统（GC-EAD）检查了雄性触角对 EE 的反应。高剂量的 EE 仅能引起雄性触角的微弱反应。接下来，我们检查了 BmOR1 基因被敲除的家蚕的触角和行为反应，该基因负责接受 bombykol。BmOR1 的敲除导致对 EE 和 EZ 的触角和行为反应完全丧失，表明如果 EE 本身是活性的，它通过对 BmOR1 的偶然刺激而不是通过对 EE 特异性受体的刺激来诱导这些反应。从信息素生物合成和信息素通讯系统的进化角度讨论了家蚕和野桑蚕 PG 中 EE 的存在。
