ANALYSIS OF THE BR-C LOCUS TRANSCRIPTIONAL ACTIVITY IN DROSOPHILA-VIRILIS

The locus BR-C, responsible for cell reaction to the hormone ecdystero ne in Drosophila virilis, was previously cloned and mapped. This locus occupies a region of about 100 kb. To define exon location and a mode of D. virilis BR-C expression at different stages of development (emb ryos; first, second, and third instar; early, middle and late pupae; a dult flies), Northern blot hybridization was conducted. Poly(A)+ RNA, isolated from D. virilis flies at these developmental stages, was hybr idized with fragments of the BR-C locus DNA. This D. irilis gene was s hown to encode at least six different transcripts that were 10, 5.5, 4 .4, 3.8, 3.3, and 2.7 kb in size. The highest gene expression is attai ned at the second and third instar and at the late pupa stage.