[Transcriptional activity of the BR-C locus in Drosophila virilis]

The locus BR-C, responsible for cell reaction to the hormone ecdysterone 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 (embryos; first, second, and third instar; early, middle and late pupae; adult flies), Northern blot hybridization was conducted. Poly(A)+ RNA, isolated from D. virilis flies at these developmental stages, was hybridized with fragments of the BR-C locus DNA. This D. virilis gene was shown 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 attained at the second and third instar and at the late pupa stage.