CONSERVATION OF COMPLEX EXPRESSION DOMAINS OF THE PDM-2 POU DOMAIN GENE BETWEEN DROSOPHILA-VIRILIS AND DROSOPHILA-MELANOGASTER

The closely linked pdm-1 and pdm-2 genes of Drosophila are expressed in complex patterns that suggest diverse roles in segmentation and nervous system development. A D. virilis pdm cDNA clone was isolated and sequenced. It shares sequence similarity with just the POU domain region of pdm-1, but shares extensive sequence similarity with the largest exon of pdm-2. In situ hybridization to D. virilis embryos shows that virtually all aspects of pdm-2 expression are conserved between D. virilis and D. melanogaster. This includes initial expression in a gap gene-like posterior domain, expression in ectodermal stripes during germ band extension, broad expression in the neurectoderm followed by limitation to discrete subsets of CNS cells, and expression in specific PNS neurons and support cells. The conservation of these expression domains supports the idea that the pdm genes are important for a variety of cell fate decisions in Drosophila development.