Analysis of the locomotor circuit formation in zebrafish spinal cord

脊髓腹侧p2祖结构域产生两种中间神经元亚型，V2a和V2b。关于V2a和V2b神经元如何从单一祖域产生的机制尚不清楚。我们在本研究中发现p2祖细胞分裂一次产生V2a/V2b神经元对，表明V2a和V2b神经元是由产生对的祖细胞不对称分裂产生的。我们还发现姐妹细胞之间的Delta-Notch相互作用在这些不对称分裂的最终结果中起着关键作用。这种决定细胞命运的机制类似于果蝇神经发生过程中的不对称分裂，神经节母细胞分裂一次产生不同的神经元。然而，与果蝇不同，斑马鱼p2祖细胞的分裂轴并不是固定的。我们报道了脊椎动物神经发生中成对产生祖细胞的最终分裂可以通过一种可能不依赖于分裂轴方向的机制可重复地产生两个不同的神经元。

The p2 progenitor domain in the ventral spinal cord gives rise to two interneuron subtypes, V2a and V2b. The mechanism as to how V2a and V2b neurons arise from a single progenitor domain was unknown. We showed in this study that p2 progenitors divide once to produce V2a/V2b neuron pairs, indicating that V2a and V2b neurons are generated by the asymmetric division of pair-producing progenitor cells. We also showed that Delta-Notch interactions between sister cells play a critical role in the final outcome of these asymmetric divisions. This mechanism for determining cell fate is similar to asymmetric divisions that occur during Drosophila neurogenesis, where ganglion mother cells divide once to produce distinct neurons. However, unlike in Drosophila, the divisional axes of p2 progenitors in zebrafish were not fixed. We report that the terminal division of pair-producing progenitor cells in vertebrate neurogenesis can reproducibly produce two distinct neurons through a mechanism that may not depend on the orientation of the division axis.