01-P028 A novel nuage component gene Tejas is required for female fertility in Drosophila melanogaster

lyzes the maturation of micro RNAs (miRNA) by endoribonucleolytic cleavage of double stranded RNA precursors. This process is central to the process of RNA interference. Gene trap experiments abolishing the function of Dicer1 and therefore the production of miRNAs result in embryonic lethality [Bernstein, E. etal., 2003. Dicer is essential for mouse development. Nature Genetics 35, 215–217]. Thus far we studied the expression pattern of Dicer1 in mouse embryonic retinae using immunohistochemistry and insitu hybridisation. Dicer1 is expressed at E14.5 throughout the retina, in particular in the retinal ganglion cell (RGC) and the neuroblast regions. Expression in the neuroblast region diminishes towards E18.5, whereas the expression in the RGC layer is maintained. Additionally, Dicer1 mRNA is expressed in a dorso-ventral gradient in the retina. Furthermore, we report expression of Dicer1 in perinuclear regions of postmitotic TuJ1 positive neurons, but not their axons, in dissociated cell cultures. At the same time we did not detect Dicer1 in amacrine cells expressing syntaxin. This forms a basis for ongoing studies investigating the invivo function of Dicer1 in such aspects of neural development as cell cycle dynamics in progenitor population, choice of cell fate, axon guidance, lamination, cell death or autophagy.