Development and specification of photoreceptor neurons in Drosophila larva
(Maria Tsachaki, Abhishek Kumar Mishra, Diarra Bao)


 Light-dependent information of the surrounding world is perceived by the visual system. Specialized photoreceptor neurons (PRs) in the eye are able to transform distinct wavelengths of the light into neuronal encoded information. The actual photoreceptor proteins are light-sensitive G-protein coupled receptors termed Rhodopsins. The developmental process and genetic mechanisms coordinating the expression of specific sensory receptor genes thus provides functional identity to sensory neurons.

The larval eye of Drosophila represents is a comparably simple visual organ only composed of 12 PRs, which are further subdivided into two types. Four PRs are blue-sensitive defined by the expression of rhodopsin5 (rh5) eight PRs express the green-sensitive rhodopsin6 (rh6).

We have identified a set of three transcription factors (Sal, Svp and Otd) to be mediating the choice of larval PRs to either express rh5 or rh6 (Sprecher et al., 2007, GENES DEV). The genetic mechanisms are surprisingly different from the ones acting in the retina of the adult animal.

We are now investigating how Sal, Svp and Otd specifying distinct PR-subtype identities, what transcription factors are downstream or upstream and how are the rhodopsins regulated in the two PR-subtypes. We have performed microarrays on the two PR-subtypes for genes that are differentially expressed.





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