Analysis of the amplification and transcription of the C3-22 gene of Rhynchosciara americana (Diptera: Sciaridae) in transgenic lines of Drosophila melanogaster.

Drosophila melanogaster was transformed with an 18 kb fragment of the C3 DNA puff of Rhynchosciara americana, including the C3-22 gene and the origins of replication that direct amplification. Different tissues and developmental stages of five independent transgenic lines were analyzed by quantitative Southern blot hybridization. No indication was found that the transformed fragment was amplified, strongly suggesting that factors involved in DNA puff amplification have not been conserved in Drosophila. Transcription of the C3-22 gene in the transgenic lines was found to be at a low and constitutive level throughout development. These results indicate that, unlike other DNA puff genes, the factors that regulate the C3-22 gene are not conserved in Drosophila.