GENETIC INTERACTIONS AND CELL BEHAVIOR IN BLISTERED MUTANTS DURING PROLIFERATION AND DIFFERENTIATION OF THE DROSOPHILA WING

In this work, we analyse the blistered function in wing vein developme nt by studying genetic mosaics of mutant cells, genetic interactions w ith other genes affecting vein development and blistered expression in several mutant backgrounds. blistered encodes for a nuclear protein h omologous to the mammalian Serum Response Factor and is expressed in p resumptive intervein cells of third larval instar and pupal wing discs . Clones of blistered mutant cells proliferate normally but tend to gr ow along veins and always differentiate as vein tissue. These observat ions indicate that vein-determined wing cells show a particular behavi our that is responsible for their allocation to vein regions, We obser ve strong genetic interactions between blistered, veinlet and genes of the Ras signaling cascade. During disc proliferation, blistered expre ssion is under the control of the Ras signal transduction pathway, but its expression is independent of veinlet, During the pupal period, bl istered and veinlet expression become interdependent and mutually excl usive, These results link the activity of the Ras pathway to the proce ss of early determination of intervein cells, by the transcriptional c ontrol of the blistered nuclear factor.