Castelli-Gair J, Greig S, Micklem G, Akam M
Wellcome/CRC Institute, Cambridge, UK.
Development. 1994 Jul;120(7):1983-95. doi: 10.1242/dev.120.7.1983.
Homeotic genes confer identity to the different segments of Drosophila. These genes are expressed in many cell types over long periods of time. To determine when the homeotic genes are required for specific developmental events we have expressed the Ultrabithorax, abdominal-A and Abdominal-Bm proteins at different times during development using the GAL4 targeting technique. We find that early transient homeotic gene expression has no lasting effects on the differentiation of the larval epidermis, but it switches the fate of other cell types irreversibly (e.g. the spiracle primordia). We describe one cell type in the peripheral nervous system that makes sequential, independent responses to homeotic gene expression. We also provide evidence that supports the hypothesis of in vivo competition between the bithorax complex proteins for the regulation of their down-stream targets.
同源异型基因赋予果蝇不同体节特定的特征。这些基因在许多细胞类型中长时间表达。为了确定同源异型基因在特定发育事件中何时是必需的，我们利用GAL4靶向技术在发育的不同时间表达了超双胸、腹A和腹Bm蛋白。我们发现早期短暂的同源异型基因表达对幼虫表皮的分化没有持久影响，但它会不可逆地改变其他细胞类型的命运（例如气门原基）。我们描述了外周神经系统中的一种细胞类型，它对同源异型基因的表达做出连续、独立的反应。我们还提供了证据支持双胸复合体蛋白在体内竞争调节其下游靶点这一假说。
