Cell fate specification in the Drosophila retina.
Cell fate specification in the Drosophila retina.
复制标题
果蝇视网膜中的细胞命运规范。
DOI：
10.1007/978-3-540-46826-4_6
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发表时间：
2000
影响因子：
--
通讯作者：
Moses,K
中科院分区：
文献类型：
--
作者：
Kumar,JP;Moses,K
果蝇（Drosophila melanogaster）的复眼是一个有用的模型系统，用于研究细胞命运规范的基础问题。十多年前，汤姆林森和雷迪提出，果蝇眼内的细胞利用一种组合信号编码来获得特定的细胞身份。这一概念促使我们努力理解苍蝇眼的各个方面是如何组合在一起的（Ready et al. 1976; Tomlinson 1985）。五眼作为一个实验系统的吸引力也在于其简单的成人结构以及其精确和定型的发展。当然，这与果蝇基因技术发现基因的非凡能力有关（本章提到的基因在表1中进行了总结）。我们将尝试总结关于加入发育单位眼或小眼的第一个（R8）和最后一个（R7）光感受器的分子发育的已知情况。我们之所以关注这两种细胞，部分原因是我们对它们发育背后的分子和机制了解得最好。这两个细胞所使用的机制，一个用于R8的原细胞，一个用于R7的诱导细胞，在发育过程中反复使用。从这两种细胞的发展中吸取的经验教训对其他实验系统具有相当大的意义。近800个相同的单眼或小眼组成了果蝇的复眼，排列成近乎晶体的阵列。在每个小囊内组装的只有20个不同的细胞，每个细胞在小面内占据精确的位置（图1）。在小眼状突起的中心有8个感光神经元（标记为Rl-8），它们以不对称的梯形模式排列。在感光器核心的上方有四个分泌晶状体的视锥细胞。围绕着小眼核心的是一层色素细胞鞘，它在光学上将一个小眼与另一个小眼隔离开来。成人复眼来源于单层上皮，即眼触须象盘。在第三个幼虫阶段，图案形成
The compound eye of the fruit fiy, Drosophila melanogaster, is a useful model system for investigating the issues that underlie cell fate specification. More than a decade ago, Tomlinson and Ready proposed that the cells within the fiy eye make use of a combinatorial code of signals in adopting specific cellular identities. This concept has driven our effort to understand how the individual facets of the fiy eye are assembled (Ready et al. 1976; Tomlinson 1985). The attraction of the fiyeye as an experimental system also rests within its simple adult structure along with its precise and stereotyped development. This is, of course, coupled to the extraordinary power of Drosophila genetic techniques to discover genes (the genes mentioned in this chapter are summarized in Table 1). We will attempt to summarize what is known about the molecular development of the first (R8) and last (R7) photoreceptors to join the developing unit eye or ommatidia. Weare focusing on these two cells, in part, because the molecules and mechanisms that underlie their development are the best understood. The mechanisms used by these two cells, a proneural one for R8 and an inductive one for R7, are repeatedly used during development. Lessons learned from the development of these two cells have considerable implications for other experimental systems. Arranged in a nearly crystalline array are nearly 800 identical unit eyes or ommatidia that comprise the compound eye of Drosophila. Assembled within each ommatidium are just 20 differing cells, each occupying a precise position within the facet (Fig. 1). At the heart of the ommatidium lie eight photoreceptor neurons (labeled Rl-8) that are arranged in an asymmetric trapezoidal pattern. Above the photoreceptor core lie four cone cells that secrete the overlying lens. Surrounding the ommatidial core is a sheath of pigment cells that optically insulate one ommatidium from another. The adult compound eye is derived from a monolayer epithelium, the eyeantennal imaginal disk. During the third larval ins tar, pattern formation