Ning Chao, Yang Ke, Xu Meng, Huang Ling-Qiao, Wang Chen-Zhu
State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
Insect Biochem Mol Biol. 2016 Jun;73:12-9. doi: 10.1016/j.ibmb.2016.04.002. Epub 2016 Apr 7.
Adult moths possess an organ in their labial palps, the labial-palp pit organ, which is specialized for sensing carbon dioxide (CO2). They use CO2 as a cue to detect healthy plants and find food or lay eggs on them. The molecular bases of the CO2 receptor in Drosophila melanogaster and Aedes aegypti have been reported, but the molecular mechanisms of the CO2 receptor in Lepidoptera remains elusive. In this study, we first re-examined three putative Helicoverpa armigera CO2 gustatory receptor genes (HarmGr1, HarmGr2, and HarmGr3), and then analyzed expression patterns of them. RT-PCR results verified they were predominantly expressed in the labial palps of H. armigera. Thus, we used in situ hybridization to localize the expression of three genes in the labial palps. We found that all three genes were co-expressed in the same cells of the labial palps. Next, we employed the Xenopus laevis oocyte expression system and the two-electrode voltage-clamp recording to study the function of the three genes. Results showed that only oocytes co-expressing HarmGr1 and HarmGr3 or co-expressing HarmGr1, HarmGr2 and HarmGr3 gave robust responses to NaHCO3. Finally, we confirmed that the sensory cells in labial palps of both females and males show dose dependent responses to CO2 stimuli by using single sensillum recording. Our work uncovers that HarmGr1 and HarmGr3 are indispensable and sufficient for CO2 sensing in labial palps of H. armigera.
成年蛾类在其唇须中拥有一种器官，即唇须凹坑器官，该器官专门用于感知二氧化碳（CO₂）。它们利用CO₂作为线索来检测健康的植物，并在上面寻找食物或产卵。黑腹果蝇和埃及伊蚊中CO₂受体的分子基础已有报道，但鳞翅目昆虫中CO₂受体的分子机制仍不清楚。在本研究中，我们首先重新检测了三种假定的棉铃虫CO₂味觉受体基因（HarmGr1、HarmGr2和HarmGr3），然后分析了它们的表达模式。RT-PCR结果证实它们主要在棉铃虫的唇须中表达。因此，我们使用原位杂交来定位这三个基因在唇须中的表达。我们发现这三个基因在唇须的相同细胞中共表达。接下来，我们采用非洲爪蟾卵母细胞表达系统和双电极电压钳记录来研究这三个基因的功能。结果表明，只有共表达HarmGr1和HarmGr3或共表达HarmGr1、HarmGr2和HarmGr3的卵母细胞对NaHCO₃有强烈反应。最后，我们通过单感器记录证实，雌性和雄性棉铃虫唇须中的感觉细胞对CO₂刺激均表现出剂量依赖性反应。我们的研究揭示了HarmGr1和HarmGr3对于棉铃虫唇须中CO₂感知是不可或缺且足够的。
