Evolutionary specialization of neuronal core circuits in arthropod olfactory systems: structure and function of convergence/divergence in crustaceans versus insects

节肢动物嗅觉系统神经元核心回路的进化特化：甲壳类动物与昆虫趋同/趋异的结构和功能

• 批准号: 430592330
• 负责人: Professor Dr. Steffen Harzsch
• 金额: --
• 依托单位: Abteilung Evolutionäre Neuroethologie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/430592330?language=en
• 关键词: Evolutionary; specialization; neuronal; core; circuits

According to all recent molecular phylogenies, insects must be regarded as a highly successful terrestrial animal group that originated from marine crustaceans. The main chemosensory organ of both taxa for distance olfaction is the most anterior pair of head appendages, the deutocerebral antennae. Olfactory sensory neurons associated with sensilla on the antennae project their axons into the brain’s primary olfactory centres, the bilaterally paired antennal lobes (insects)/olfactory lobes (crustaceans). There, sensory olfactory afferents synapse with two classes of olfactory interneurons (OSNs), the local olfactory interneurons (LNs) and the olfactory projection neurons (PNs), within specialized neuropil compartments, the olfactory glomeruli. Although the principle wiring pattern within the glomeruli of crustaceans and insects share many similarities, nevertheless there also exist pronounced difference of these olfactory core circuits. Therefore, this system can be seen as an ideal playground for those interested in analysing evolutionary diversification of neuronal core circuits. For example, our results from phase 1 of the PP strongly suggest that what is currently described as „canonical olfactory system organization” e.g. in the benchmark system Drosophila melanogaster likely is a derived character state that evolved from a distributed representation / combinatorial coding, and more and more examples from crustaceans and from within the insects emerge as deviations from this pattern. By comparing insects and crustaceans we can study the end point of past evolutionary optimization processes. This project brings together two experts on the functional and evolutionary morphology of crustacean (HAR) and insect (RYB) olfactory system and a computational neuroscientist with a strong background in arthropod olfactory systems (NAW). In the prolongation proposal, we want to continue our successful collaboration from phase 1 of the PP and gain more detailed insights into the neuroanatomy of the central olfactory pathway in non-model insects and crustaceans beyond the well studied model system D. melanogaster. By quantifying the numbers of the involved neuronal elements (olfactory sensory neurons, local olfactory interneurons, projection neurons, olfactory glomeruli) and by analysing projectomic characteristics of the OSN to PN to output pathway (mushroom bodies) we will gain additional insights into divergence versus convergence and evolutionary specialization of the central olfactory pathways in arthropod lineages. Furthermore, by obtaining ultrastructural data we will continue to understand the evolutionary optimization of the connectivity of OSNs to PNs. Finally, by further evolving a mathematical model of information processing within olfactory glomeruli of different arthropod lineages as developed in phase 1, we want to further understand the existing differences of olfactory coding mechanisms in insects versus crustaceans.

根据所有最近的分子遗传学，昆虫必须被认为是一个非常成功的陆地动物群体，起源于海洋甲壳类动物。这两个分类群的主要化学感受器官的距离嗅觉是最前面的一对头部附属物，中脑触角。与触角上的感受器相关的嗅觉感觉神经元将其轴突投射到大脑的主要嗅觉中心，即两侧成对的触角叶（昆虫）/嗅叶（甲壳类动物）。在那里，感觉嗅觉传入神经与两类嗅觉中间神经元（OSN），局部嗅觉中间神经元（LN）和嗅觉投射神经元（PN）突触，在专门的神经元隔室，嗅觉肾小球。虽然甲壳类动物和昆虫的嗅球内的主要线路模式有许多相似之处，但这些嗅觉核心回路也存在明显的差异。因此，对于那些有兴趣分析神经元核心电路进化多样性的人来说，这个系统可以被视为一个理想的游乐场。例如，我们的PP第1阶段的结果强烈表明，目前在基准系统Drosophila melanogaster中描述的“典型嗅觉系统组织”可能是从分布式表示/组合编码进化而来的衍生特征状态，越来越多的甲壳类动物和昆虫的例子出现了偏离这种模式的情况。通过比较昆虫和甲壳类动物，我们可以研究过去进化优化过程的终点。该项目汇集了两名甲壳类动物（HAR）和昆虫（RYB）嗅觉系统的功能和进化形态学专家，以及一名具有节肢动物嗅觉系统（NAW）强大背景的计算神经科学家。在延长提案中，我们希望继续我们在PP第1阶段的成功合作，并在研究良好的模型系统D之外，对非模型昆虫和甲壳类动物的中央嗅觉通路的神经解剖学获得更详细的见解。黑腹菌通过量化所涉及的神经元元素（嗅觉感觉神经元，局部嗅觉中间神经元，投射神经元，嗅觉肾小球）的数量，并通过分析的投射特征的OSN PN输出通路（蘑菇体），我们将获得更多的见解分歧与收敛和进化专业化的中央嗅觉通路在节肢动物谱系。此外，通过获得超微结构数据，我们将继续了解OSN与PN连接的进化优化。最后，通过进一步发展的数学模型的信息处理不同的节肢动物谱系内的嗅觉小球在第一阶段中开发的，我们要进一步了解昆虫与甲壳类动物的嗅觉编码机制的现有差异。