Development of the insect compound eye requires a highly controlled interplay between transcription factors. However, the genetic mechanisms that link early eye field specification to photoreceptor terminal differentiation and fate maintenance remain largely unknown. Here, we decipher the function of 2 transcription factors, Glass and Hazy, which play a central role during photoreceptor development. The regulatory interactions between Glass and Hazy suggest that they function together in a coherent feed-forward loop in all types of Drosophila photoreceptors. While the glass mutant eye lacks the expression of virtually all photoreceptor genes, young hazy mutants correctly express most phototransduction genes. Interestingly, the expression of these genes is drastically reduced in old hazy mutants. This age-dependent loss of the phototransduction cascade correlates with a loss of phototaxis in old hazy mutant flies. We conclude that Glass can either directly or indirectly initiate the expression of most phototransduction proteins in a Hazy-independent manner, and that Hazy is mainly required for the maintenance of functional photoreceptors in adult flies.

昆虫复眼的发育需要转录因子之间高度受控的相互作用。然而，将早期的眼场规范与感光器终末分化和命运维持联系起来的遗传机制仍然未知。在这里，我们破译了2个转录因子Glass和Hazy的功能，它们在感光器发育过程中起着核心作用。Glass和Hazy之间的调节相互作用表明，它们在所有类型的果蝇感光细胞中均以连贯的前馈回路的形式起作用。虽然玻璃突变体的眼睛几乎不表达所有的感光细胞基因，但年轻朦胧突变体正确表达大多数光转导基因。有趣的是，这些基因的表达在古老的朦胧突变体中急剧减少。光转导级联的这种与年龄有关的损失与旧的朦胧突变果蝇的趋光性损失有关。我们得出的结论是，Glass可以以不依赖雾霾的方式直接或间接启动大多数光转导蛋白的表达，并且雾霾是维持成年果蝇功能性光感受器的主要动力。