Département des Neurosciences Fondamentales, Université de Lausanne, Lausanne, CH-1005 Switzerland; email:
Annu Rev Genet. 2017 Nov 27;51:455-476. doi: 10.1146/annurev-genet-120116-024648. Epub 2017 Sep 20.
The evolution of a nervous system as a control system of the body's functions is a key innovation of animals. Its fundamental units are neurons, highly specialized cells dedicated to fast cell-cell communication. Neurons pass signals to other neurons, muscle cells, or gland cells at specialized junctions, the synapses, where transmitters are released from vesicles in a Ca-dependent fashion to activate receptors in the membrane of the target cell. Reconstructing the origins of neuronal communication out of a more simple process remains a central challenge in biology. Recent genomic comparisons have revealed that all animals, including the nerveless poriferans and placozoans, share a basic set of genes for neuronal communication. This suggests that the first animal, the Urmetazoan, was already endowed with neurosecretory cells that probably started to connect into neuronal networks soon afterward. Here, we discuss scenarios for this pivotal transition in animal evolution.
神经系统作为身体功能的控制系统的进化是动物的一个关键创新。其基本单位是神经元，这是一种高度专业化的细胞，专门用于快速的细胞间通讯。神经元在专门的连接处（突触）将信号传递给其他神经元、肌肉细胞或腺细胞，在那里，递质以 Ca2+依赖的方式从囊泡中释放出来，激活靶细胞膜中的受体。从更简单的过程中重建神经元通讯的起源仍然是生物学的一个核心挑战。最近的基因组比较表明，所有动物，包括无神经系统的多孔动物和扁盘动物，都共享一套基本的神经元通讯基因。这表明，第一个动物——原始后生动物，已经具备了神经分泌细胞，这些细胞可能在不久之后就开始连接成神经元网络。在这里，我们讨论了动物进化中这一关键转变的几种情况。
