Basler K, Hafen E
Zoologisches Institut, Universität Zürich, Switzerland.
Development. 1989 Dec;107(4):723-31. doi: 10.1242/dev.107.4.723.
The development of the compound eye of Drosophila consists of a linear, stereotyped program starting at the posterior end of the eye imaginal disc and progressing towards the anterior border. The determination of the R7 photoreceptor cells is part of this process and is dependent on the sevenless gene. In this study, we used a heat-shock-inducible sevenless gene as a conditional allele to determine the exact temporal requirements of sevenless gene expression and to reveal the stages of ommatidial development during which the presumptive R7 cell can respond to the presence of sevenless protein. Our results indicate that sevenless gene function is only required during a brief, defined period for the initiation of R7 development; subsequently sevenless is dispensable for both differentiation and function of the R7 photoreceptors. Furthermore, using rescue of R7 cells as an internal marker to monitor the progression of eye development we could examine when and at what rate ommatidial columns form.
果蝇复眼的发育由一个线性的、模式化的程序组成，该程序从眼成虫盘的后端开始，向前缘推进。R7光感受器细胞的确定是这个过程的一部分，并且依赖于无七基因。在本研究中，我们使用热休克诱导的无七基因作为条件等位基因，以确定无七基因表达的确切时间要求，并揭示小眼发育的阶段，在此期间假定的R7细胞能够对无七蛋白的存在做出反应。我们的结果表明，无七基因功能仅在R7发育起始的一个短暂、特定时期是必需的；随后，无七基因对于R7光感受器的分化和功能都是可有可无的。此外，利用R7细胞的挽救作为内部标记来监测眼发育的进程，我们可以研究小眼柱何时形成以及以何种速率形成。
