Molecular and genetic map comparison of the 2B6-2B7-8 region of the Drosophila melanogaster X chromosome

Molecular and genetic data were compared for the 2B6-2B7-8 region of the Dr osophila melanogaster X chromosome. This region contains the dor (deep oran ge) and swi (single wing) genes influencing ecdysterone-dependent gene expr ession. Genes which had not been identified previously by genetic methods w ere shown to be present in this region. Two novel loci, designated a6 and b 6, were characterized in detail. Both genes are expressed throughout Drosop hila embryogenesis. The product of b6 has a homology with mammalian pentrax ins. This is the first Drosophila gene found to contain the pentraxin motif .