Skeath J B, Zhang Y, Holmgren R, Carroll S B, Doe C Q
Howard Hughes Medical Institute, University of Illinois, Urbana 61801, USA.
Nature. 1995 Aug 3;376(6539):427-30. doi: 10.1038/376427a0.
The Drosophila central nervous system develops from a segmentally reiterated array of 30 unique neural precursors, called neuroblasts. Each neuroblast goes through a stereotyped cell lineage to produce an invariant clone of neural progeny. It is critical to identify the genes that specify neuroblast identity as these genes control the time of formation, gene expression profile, and cell lineage characteristics of each neuroblast. Here we show that the Pax-type gooseberry-distal gene specifies row 5 neuroblast identity. Initially, four rows of neuroblasts form per segment (1, 3, 5, 7) and gooseberry-distal is expressed in row 5 neuroblasts. By using 10 molecular markers, and by following the number and orientation of neuroblast divisions, we show that lack of gooseberry-distal transforms row 5 neuroblasts into row 3 neuroblasts, whereas ubiquitous gooseberry-distal generates the reciprocal transformation. Thus, gooseberry-distal is necessary and sufficient to specify row 5 neuroblast identity autonomously. The 10 genes coordinately regulated by gooseberry-distal are prime candidates for controlling specific aspects of neuroblast identity.
果蝇的中枢神经系统由30个独特的神经前体细胞（称为神经母细胞）按节段重复排列发育而来。每个神经母细胞经历一个固定的细胞谱系，产生一组固定不变的神经后代克隆。确定指定神经母细胞身份的基因至关重要，因为这些基因控制着每个神经母细胞的形成时间、基因表达谱和细胞谱系特征。在这里，我们表明Pax型远端醋栗基因指定了第5排神经母细胞的身份。最初，每个节段形成四排神经母细胞（第1、3、5、7排），远端醋栗在第5排神经母细胞中表达。通过使用10种分子标记，并跟踪神经母细胞分裂的数量和方向，我们发现缺乏远端醋栗会将第5排神经母细胞转变为第3排神经母细胞，而普遍存在的远端醋栗则会产生相反的转变。因此，远端醋栗对于自主指定第5排神经母细胞的身份是必要且充分的。由远端醋栗协同调节的10个基因是控制神经母细胞身份特定方面的主要候选基因。
