Bipolar Cells in the Spotlight Cause for Excitement

(Perron et al., 1999). However, there are relatively few the sensory structures take on one of two alternative fates (Gupta and Rodrigues, 1997; Goulding et al., 2000). experiments in which the comparative potential of different proneural proteins has been analyzed directly. The In conclusion, the identification of amos highlights the importance of proneural proteins in contributing to results from Drosophila demonstrate that it is possible to distinguish characteristics between two closely related sensory organ specificity as well as neural competence. Clearly, one key to our further understanding of neural proteins of the Atonal subfamily. Thus, it would be interesting to extend the studies in vertebrates to test out development will be to identify the targets of proneural proteins, both to find those that are activated by all the specificities of the different homologs in comparable assays. proneural proteins and those that are specific to each proneural protein and subtype of sensillae. This will The misexpression experiments in Drosophila demonstrate that individual proneural proteins can have some allow us to learn what is required to elaborate neural development on the one hand and what is required to unique properties. However, these experiments also reveal considerable overlap in their activities, since scute, dictate the ways that the different types of sensory structures develop on the other. atonal, and amos can all produce external sensory organs (ES) when misexpressed, even though only scute is implicated in normal ES development. The fact that Sarah Bray all three proteins elicit ES formation suggests that this Department of Anatomy is the default route for sensory organ development and University of Cambridge that there is a common set of target genes. All three Downing Street proneural proteins would activate this common contin-Cambridge CB2 3DY gent, which could include genes such as asense (a sec-United Kingdom ondary proneural gene that is expressed in all neural precursors) and Delta (encoding a ligand for Notch) and would be sufficient to elicit ES development. The ability outside the ectoderm, and other tissue-specific targets are likely to be activated instead. For example, the meso-derm bHLH transcription factor Twist could cooperate with proneural proteins to activate muscle-specific genes and inhibit neural-specific genes in the muscle precursors. It is not clear whether there needs to be Bipolar Cells in the Spotlight: a similar " ectoderm " factor that collaborates with the proneural proteins to elicit sensory organ development or whether in the absence of …