Functional dissection of dopaminergic neurons underlying male-male courtship behavior in Drosophila

Abstract

[[abstract]]求偶是自然界動物的一種本能，動物利用許多種感覺訊號去辨識同種間且合適的伴侶進行求偶行為，進而繁演後代。通常求偶行發生於異性之間；然而，研究證實自然界中之動物同性之間的求偶與性行為在許多物種間皆存在，所涉及的生物因子與分子機轉目前仍尚未被釐清。果蠅在遺傳學上提供了適切的遺傳分析工具與大規模研究的優勢，同時求偶行為的分析與量化已被清楚的確定。正常情況下，果蠅之間很少會出現同性求偶行為，利用基因操作的手法可以大幅提高這些行為的發生。多巴胺(Dopamine；DA)對於動物而言是一個非常重要的神經傳導物質；在許多研究陸續發現，多巴胺含量不正常表現時，會大幅增加同性求偶行為的發生。在本研究中，藉由Murashka-1 Gal4驅動多巴胺生合成路徑之酪胺酸羥化?(tyrosine hydroxylase；TH)大量表現，將導致Murashka-1神經元之多巴胺分泌量升高，可明顯觀察到雄果蠅同性間之求偶行為，但不會影響其對雌性果蠅的求偶行為。另外，本文也藉由UAS-THi基因轉殖果蠅，透過核醣核酸干擾酪胺酸羥化?的表現，在零照度下可以觀察到當Murashka-1神經元之多巴胺分泌量降低之雄性果蠅吸引Murashka-1神經元之多巴胺分泌量升高之雄性果蠅進行求偶行為。本論文顯示Murashka-1神經元，在調控雄果蠅同性間求偶行為的發生扮演了重要的角色。[[abstract]]Courtship behavior is fundamental to the propagation of animal species. Animals use multiple sensory cues to recognize conspecifics and to choose a potentially suitable mate for reproduction. A courtship behavior occurs in heterosexual usually. The recent study found that sexual behavior between males is observed in many species, but the biological factors involved are poorly known. Although wild-type male flies rarely show male–male courtship, the frequency and intensity of this behavior can be strongly increased by genetic manipulation. Dopamine (DA) is a very important neuromodulator in animals. Its role in mammal heterosexual behavior has been extensively studied. Studies demonstrate that DA elevation can enhance male-male courtship behavior in Drosophila. We used genetic approach to increasing dopamine level by UAS-TH under a driver of Murashka-1 and showed enhanced propensity to court other males but did not change their courtship toward virgin females and locomotor activity. Consistently, the knocking downs of dopamine by UAS-THi under a same driver of Murashka-1 and investigated increased male attractiveness or decrease aversiveness towards other males in dark. Our results show that the Murashka-1 expressing neurons played an important role in the regulation of the promotion of male courtship among fruit flies homosexual behavior among the production.[[note]]碩