雌果蝇引起雄-雄攻击行为的分子与神经细胞机制

In the Darwinian "struggle between the males for possession of the females", male-male aggression is stimulated by females who do not fight as much as males. Little is known about the molecular and cellular mechanisms of this evolutionarily important process. I report here that the female specific pheromone (z,z)-7,11-heptacosadiene (7,11-HD), is important for stimulating intermale aggression in Drosophila. Given olfaction is required for female induced aggression, I plan to figure out what is the specific odorant receptor neurons (ORNs) which could be activated by 7,11-HD with electroantennogram and in vivo calcium imaging. The involvement of 7,11-HD activated ORNs in female and 7,11-HD induced aggression will be analyzed with male flies knocking-out specific odorant receptor gene, with males expressing a toxin protein in specific ORNs, or with males expressing a temperature sensitive synaptic vesicle protein (Shibirets). The sufficiency of the ORNs in intermale aggression will be tested via artificial activation of the ORNs in a stimulus free aggression assay. The results will uncover a molecular mechanism for female stimulation of intermale aggression and suggest that specific ORNs mediate behavioral and electrophysiological responses to the most abundant female pheromone 7,11-HD.

雄性为了争夺雌性互相攻击是进化保守且重要的行为。这一行为的分子与细胞机制还有待研究。本项目通过研究黑腹果蝇在雌蝇诱导下的雄－雄攻击行为，找到雌蝇发出并引起雄－雄攻击的信息素7,11-heptacosadiene (7,11-HD)；通过触角场电位记录及活体钙成像技术分析找出被7,11-HD激活的嗅觉受体神经元；通过在这些神经元表达毒素杀死神经元、或者表达温度敏感的突触囊泡蛋白（Shibire）在高温时抑制突触传递、或者直接进行基因剔除，分析上述三种条件产生的雄蝇，在雌蝇和7,11-HD诱导下的雄－雄攻击行为是否有缺陷；最后通过在这些神经元表达温度敏感的阳离子通道（dTrpA1）,人为升高温度来激活神经元，观察在没有诱惑物的情况下雄－雄攻击行为是否因为神经元被激活而升高。以上实验的完成将揭示：7,11-HD作为雌蝇发出的信号分子通过激活雄蝇特定的嗅觉受体神经元，导致雄-雄攻击行为的发生。