Steller H, Fischbach K F, Rubin G M
Cell. 1987 Sep 25;50(7):1139-53. doi: 10.1016/0092-8674(87)90180-2.
Mutations at the X-linked disconnected locus of D. melanogaster lead to the failure of adult photoreceptor axons to innervate their target cells in the developing optic lobes of the third instar larva, resulting in flies that have rudimentary optic ganglia. The cascade of epigenetic events leading to the adult disconnected phenotype is caused by the misrouting of a larval pioneer nerve, Bolwig's nerve, during embryonic development. In the disconnected mutant this nerve fails to recognize and establish stable connections with its correct synaptic partners. In addition, disconnected affects both the proper aggregation and the movement of the Bolwig neurons to their final location in the embryo. Finally, similar but more subtle defects can be found in a subset of other peripheral neurons in the thoracic and abdominal segments. The different aspects of the phenotype suggest that the disconnected gene plays a role in neuronal cell recognition.
果蝇X连锁的“分离”基因座发生突变，会导致成年光感受器轴突无法在三龄幼虫发育中的视叶中支配其靶细胞，从而产生视神经节发育不全的果蝇。导致成年“分离”表型的一系列表观遗传事件，是由胚胎发育过程中一条幼虫先驱神经——博尔维格氏神经的错误布线引起的。在“分离”突变体中，这条神经无法识别并与其正确的突触伙伴建立稳定连接。此外，“分离”基因还影响博尔维格神经元的正常聚集及其向胚胎中最终位置的移动。最后，在胸段和腹段的其他一些外周神经元亚群中也能发现类似但更为细微的缺陷。该表型的不同方面表明，“分离”基因在神经元细胞识别中发挥作用。
