Macroglomeruli for fruit odors change blend preference in Drosophila
Macroglomeruli for fruit odors change blend preference in Drosophila
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DOI：
10.1007/s00114-010-0727-2
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发表时间：
2010-12-01
影响因子：
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通讯作者：
Dekker, Teun
中科院分区：
文献类型：
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作者：
Ibba, Irene;Angioy, Anna Maria;Dekker, Teun
果蝇的嗅觉回路越来越清晰。然而，嗅觉处理如何转化为适当的行为反应仍然知之甚少。使用兄弟物种的方法，我们测试了如何在嗅觉回路的扰动影响气味偏好。在以前的研究中，我们发现D. melanogaster，专家D. sechellia过度代表了一个感器ab 3，其A神经元对己酸酯敏感，这是该物种唯一宿主巴戟天大溪地果实的特征。相应地，相应的肾小球DM 2增大。在这项研究中，我们发现，ab 3B神经元，其扩展以前被认为是多效性的，没有生态意义，实际上是调整到另一个巴戟天水果挥发性，2-庚酮（HP）。这种神经元类型的轴突在第二个扩大的肾小球中呈树枝状。在行为实验中，我们测试了这如何影响苍蝇的气味偏好。我们证明了D. Secchellia对这些大肾小球的关键配体具有相反的偏好，特别是在高浓度下。而D. melanogaster被高浓度的这些气味所排斥，D.塞切利亚被深深地吸引住了。这是单独存在的气味的情况，但更值得注意的是其混合物。我们的研究表明，相对简单的变化，如感觉器丰度的变化，以及肾小球大小的一致变化，可以扭曲由此产生的嗅觉代码，并可能导致气味偏好的突变。D. sechellia利用这一点使其嗅觉偏好与其生态位相一致。
The olfactory circuitry of Drosophila melanogaster is becoming increasingly clear. However, how olfactory processing translates into appropriate behavioral responses is still poorly understood. Using a sibling species approach, we tested how a perturbation in the olfactory circuitry affects odor preference. In a previous study, we found that the sibling species of D. melanogaster, the specialist D. sechellia, overrepresents a sensillum, ab3, the A neuron of which is sensitive to hexanoate esters, characteristic of the species' sole host, the Morinda citrifolia fruit. Concordantly, the corresponding glomerulus, DM2, is enlarged. In this study, we found that the ab3B neuron, the expansion of which was previously assumed to be pleiotropic and of no ecological significance, is in fact tuned to another morinda fruit volatile, 2-heptanone (HP). Axons of this neuron type arborize in a second enlarged glomerulus. In behavioral experiments we tested how this has affected the fly's odor preference. We demonstrate that D. sechellia has a reversed preference for the key ligands of these macroglomeruli, especially at high concentrations. Whereas D. melanogaster was repelled by high concentrations of these odors, D. sechellia was highly attracted. This was the case for odors presented singly, but more notably for blends thereof. Our study indicates that relatively simple changes, such as a shift in sensillar abundance, and concordant shifts in glomerular size, can distort the resulting olfactory code, and can lead to saltatory shifts in odor preference. D. sechellia has exploited this to align its olfactory preference with its ecological niche.