The larval eye of Drosophila is simple and consists of two PR-types defined by the sensory receptor gene expressed: 4 PRs express the blue-sensitive rhodopsin5 (rh5) and eight PRs express the green-sensitive rhodopsin6 (rh6). Later during metamorphosis, ecdysone signaling induces a cell fate switch in the Rh5-PRs and transform it into Rh6-PRs in adult which becomes extraretinal eye or eyelet, while Rh6-PRs undergo apoptosis.
My work is focused on investigating genetic and molecular mechanism of development and cell fate determination of rhodopsins between larval eye and adult eyelet. We found that interplay of two transcription factors Senseless and Hazy regulates cell fate decisions, terminal differentiation of the larval eye and its transformation into adult eyelet. We identified a pulse expression of the zinc-finger transcription factor Senseless (Sens) to allow Rh5-PRs to differentiate by repressing the cell fate determinant Seven-up (Svp) of a Rh6-cell fate and promoting the cell fate determinant Spalt (Sal) of a Rh5-cell fate. We also found that Hazy plays a role in initiating and maintaining rhodopsin expression in the larval eye. Our findings provide a new mechanism of how the same transcription factor regulates different aspects of photoreceptor development at different stages.