Sars International Centre for Marine Molecular Biology, University of Bergen, Norway.
Essays Biochem. 2022 Dec 8;66(6):781-795. doi: 10.1042/EBC20220042.
Neurons, especially when coupled with muscles, allow animals to interact with and navigate through their environment in ways unique to life on earth. Found in all major animal lineages except sponges and placozoans, nervous systems range widely in organization and complexity, with neurons possibly representing the most diverse cell-type. This diversity has led to much debate over the evolutionary origin of neurons as well as synapses, which allow for the directed transmission of information. The broad phylogenetic distribution of neurons and presence of many of the defining components outside of animals suggests an early origin of this cell type, potentially in the time between the first animal and the last common ancestor of extant animals. Here, we highlight the occurrence and function of key aspects of neurons outside of animals as well as recent findings from non-bilaterian animals in order to make predictions about when and how the first neuron(s) arose during animal evolution and their relationship to those found in extant lineages. With advancing technologies in single cell transcriptomics and proteomics as well as expanding functional techniques in non-bilaterian animals and the close relatives of animals, it is an exciting time to begin unraveling the complex evolutionary history of this fascinating animal cell type.
神经元，特别是与肌肉结合时，使动物能够以地球上生命特有的方式与环境相互作用并在环境中活动。神经系统存在于除海绵和扁盘动物以外的所有主要动物谱系中，其组织和复杂性差异很大，神经元可能代表着最多样化的细胞类型。这种多样性导致了关于神经元和突触进化起源的大量争论，突触允许信息的定向传递。神经元在动物之外的广泛系统发生分布以及许多定义成分的存在表明这种细胞类型的起源很早，可能在第一个动物和现存动物的最后共同祖先之间的某个时间。在这里，我们重点介绍了动物之外的神经元的关键方面的发生和功能，以及非双侧对称动物的最新发现，以便对动物进化过程中第一个（或多个）神经元的出现时间和方式及其与现存谱系中发现的神经元的关系做出预测。随着单细胞转录组学和蛋白质组学技术的进步，以及非双侧对称动物和动物近亲的功能技术的扩展，现在是开始揭示这种迷人的动物细胞类型复杂进化历史的令人兴奋的时刻。
