Comparative Development of the Ant Chemosensory System.
Comparative Development of the Ant Chemosensory System.
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蚂蚁化学感应系统的比较发展。
DOI：
10.1016/j.cub.2020.05.072
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
Kronauer,DanielJC
中科院分区：
文献类型：
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作者：
Ryba,AnnaR;McKenzie,SeanK;Olivos-Cisneros,Leonora;Clowney,EJosephine;Pires,PeterMussells;Kronauer,DanielJC
昆虫触角叶（AL）是嗅觉系统的第一个突触，嗅觉感觉神经元（OSNs）在这里与二级投射神经元（PNs）接触。在黑腹果蝇中，表达特异性受体基因的OSN向约50个形态学定义的肾小球中的一个或两个发送定型投射[1-3]。OSN和PN之间精确匹配的机制已经在D. melanogaster中进行了广泛的研究，其中发育是确定性的，不依赖于神经活动[4-6]。然而，许多昆虫谱系，最值得注意的是蚂蚁，具有比黑腹果蝇大许多倍的受体基因库，并且表现出结构更复杂的触角叶[7-12]。此外，通过敲除气味受体（OR）共受体Orco来干扰OSN功能，导致蚂蚁中的AL急剧减少[13，14]，但果蝇中没有[15]。在这里，我们的特点AL发展的克隆袭击者蚂蚁，Ooceraea biroi。我们发现，与果蝇不同的是，ORs和Orco在肾小球形成之前就表达了，并且Orco蛋白被运输到发育中的轴突末端，这提高了ORs在蚂蚁AL发育过程中发挥作用的可能性。此外，在化蛹开始时切除蚂蚁触角会导致AL缺陷，重现Orcomutant表型。因此，功能性OSN神经支配的早期丧失揭示了AL中独立于外周输入而发展的潜在结构，这表明AL最初是预图案化的，后来以OSN依赖的方式进行了改进。这两个步骤的过程可能会增加发展的灵活性，从而促进蚂蚁化学感受系统的快速进化和扩展。
The insect antennal lobe (AL) contains the first synapses of the olfactory system, where olfactory sensory neurons (OSNs) contact second-order projection neurons (PNs). InDrosophila melanogaster, OSNs expressing specific receptor genes send stereotyped projections to one or two of about 50 morphologically defined glomeruli [1–3]. The mechanisms for this precise matching between OSNs and PNs have been studied extensively inD. melanogaster, where development is deterministic and independent of neural activity [4–6]. However, a number of insect lineages, most notably the ants, have receptor gene repertoires many times larger thanD. melanogasterand exhibit more structurally complex antennal lobes [7–12]. Moreover, perturbation of OSN function via knockout of the odorant receptor (OR) co-receptor,Orco, results in drastic AL reductions in ants [13, 14], but not inDrosophila[15]. Here, we characterize AL development in the clonal raider ant,Ooceraea biroi. We find that, unlike inDrosophila, ORs andOrcoare expressed before the onset of glomerulus formation, and Orco protein is trafficked to developing axon terminals, raising the possibility that ORs play a role during ant AL development. Additionally, ablating ant antennae at the onset of pupation results in AL defects that recapitulate theOrcomutant phenotype. Thus, early loss of functional OSN innervation reveals latent structure in the AL that develops independently of peripheral input, suggesting that the AL is initially pre-patterned and later refined in an OSN-dependent manner. This two-step process might increase developmental flexibility and thereby facilitate the rapid evolution and expansion of the ant chemosensory system.