Dweck Hany K M, Ebrahim Shimaa A M, Thoma Michael, Mohamed Ahmed A M, Keesey Ian W, Trona Federica, Lavista-Llanos Sofia, Svatoš Aleš, Sachse Silke, Knaden Markus, Hansson Bill S
Department of Evolutionary Neuroethology.
Mass Spectrometry Group, Max Planck Institute for Chemical Ecology, 07745 Jena, Germany.
Proc Natl Acad Sci U S A. 2015 May 26;112(21):E2829-35. doi: 10.1073/pnas.1504527112. Epub 2015 May 11.
Intraspecific olfactory signals known as pheromones play important roles in insect mating systems. In the model Drosophila melanogaster, a key part of the pheromone-detecting system has remained enigmatic through many years of research in terms of both its behavioral significance and its activating ligands. Here we show that Or47b-and Or88a-expressing olfactory sensory neurons (OSNs) detect the fly-produced odorants methyl laurate (ML), methyl myristate, and methyl palmitate. Fruitless (fru(M))-positive Or47b-expressing OSNs detect ML exclusively, and Or47b- and Or47b-expressing OSNs are required for optimal male copulation behavior. In addition, activation of Or47b-expressing OSNs in the male is sufficient to provide a competitive mating advantage. We further find that the vigorous male courtship displayed toward oenocyte-less flies is attributed to an oenocyte-independent sustained production of the Or47b ligand, ML. In addition, we reveal that Or88a-expressing OSNs respond to all three compounds, and that these neurons are necessary and sufficient for attraction behavior in both males and females. Beyond the OSN level, information regarding the three fly odorants is transferred from the antennal lobe to higher brain centers in two dedicated neural lines. Finally, we find that both Or47b- and Or88a-based systems and their ligands are remarkably conserved over a number of drosophilid species. Taken together, our results close a significant gap in the understanding of the olfactory background to Drosophila mating and attraction behavior; while reproductive isolation barriers between species are created mainly by species-specific signals, the mating enhancing signal in several Drosophila species is conserved.
被称为信息素的种内嗅觉信号在昆虫交配系统中发挥着重要作用。在模式生物黑腹果蝇中，经过多年研究，信息素检测系统的一个关键部分在行为意义及其激活配体方面一直令人困惑。在这里，我们表明表达Or47b和Or88a的嗅觉感觉神经元（OSN）能检测果蝇产生的气味月桂酸甲酯（ML）、肉豆蔻酸甲酯和棕榈酸甲酯。只表达无果（fru(M)）阳性的Or47b的OSN专门检测ML，而表达Or47b和Or47b的OSN是最佳雄性交配行为所必需的。此外，激活雄性中表达Or47b的OSN足以提供竞争交配优势。我们进一步发现，雄性对无oenocyte果蝇表现出的强烈求偶行为归因于Or47b配体ML不依赖于oenocyte的持续产生。此外，我们揭示表达Or88a的OSN对所有这三种化合物都有反应，并且这些神经元对于雄性和雌性的吸引行为都是必需且充分的。在OSN水平之上，关于这三种果蝇气味的信息通过两条专用神经线路从触角叶传递到更高的脑区。最后，我们发现基于Or47b和Or88a的系统及其配体在许多果蝇物种中都非常保守。综上所述，我们的结果填补了对果蝇交配和吸引行为嗅觉背景理解上的一个重大空白；虽然物种之间的生殖隔离屏障主要由物种特异性信号产生，但几种果蝇物种中的交配增强信号是保守的。
