A new gene nested within the dunce genetic unit of Drosophila melanogaster.

The molecular organization of the dunce gene of Drosophila melanogaster has proved to be particularly complex, with two divergently transcribed genes, Sgs-4 and Pig-1, nested within its 79 kb intron (1). Here we report the identification and the molecular characterization of a third gene nested within the transcription unit of dunce. This newly identified gene is located nearly 6 kb downstream Pig-1, within a more upstream dunce intron. The gene is developmentally regulated and transcribed with the same polarity of dunce; several lines of evidence indicate that it might encode for a salivary gland secreted (Sgs) protein.