Rodríguez I, Hernández R, Modolell J, Ruiz-Gómez M
Centro de Biología Molecular, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
EMBO J. 1990 Nov;9(11):3583-92. doi: 10.1002/j.1460-2075.1990.tb07569.x.
The Drosophila adult cuticle displays a stereotyped pattern of sensory organs (SOs). Its deployment requires the expression of the achaete (ac) and scute (sc) genes. Their products confer to cells of epidermal primordia (imaginal discs and histoblasts) the ability to become SO precursors (SOPs). In imaginal discs, ac and sc expression is spatially restricted to cell clusters within which one or a few cells become SOP(s). With the help of ubiquitous sc expression provided at different developmental times by a heat shock-sc (HSSC) chimeric gene, we have analyzed the response of epidermal primordia to the proneural action of the sc product, and have tested whether the patterned distribution of ac/sc products is necessary to position SOs correctly within the epidermis. Each primordium responds to HSSC expression by developing SOs only during a characteristic developmental period. In the absence of the endogenous ac and sc genes, most SOs induced by HSSC are of the correct type and are located in wild type positions. These results indicate that the capacity of primordia to respond to sc is temporally and spatially regulated, that specification of the type of SO does not depend on ac/sc, and that SO positioning utilizes topological information independent of the spatially restricted distribution of ac/sc products.
果蝇成虫的表皮呈现出一种定型的感觉器官（SOs）模式。其形成需要achaete（ac）和scute（sc）基因的表达。它们的产物赋予表皮原基细胞（成虫盘和组织母细胞）成为SO前体（SOPs）的能力。在成虫盘中，ac和sc的表达在空间上局限于细胞簇，其中一个或几个细胞会成为SOP。借助于热休克-sc（HSSC）嵌合基因在不同发育时期提供的普遍sc表达，我们分析了表皮原基对sc产物的神经前体作用的反应，并测试了ac/sc产物的模式分布对于在表皮内正确定位SO是否必要。每个原基仅在特定的发育时期通过发育SO来响应HSSC表达。在没有内源性ac和sc基因的情况下，HSSC诱导的大多数SO类型正确且位于野生型位置。这些结果表明，原基对sc的反应能力在时间和空间上受到调节，SO类型的指定不依赖于ac/sc，并且SO的定位利用了独立于ac/sc产物空间受限分布的拓扑信息。
