Defining the Limits and Mapping the Control Sequences of the Gene, Enhancer of Rudimentary, in Drosophila melanogaster

Abstract

The enhancer of rudimentary gene, e(r) is a highly conserved gene located on the X chromosome in Drosophila melanogaster. The gene encodes a transcriptional co-factor of 104 amino acids in length, and although the exact function is still unclear it has been shown to be involved in pyrimidine biosynthesis, oogenesis, and the cell cycle. Mutations in e(r) are characterized by low viability and decreased fertility. They have also been shown to enhance phenotypes caused by mutations in two genes involved in neurogenesis, notch and deltex, suggesting a possible role in neurogenesis. In the present study, transgenes of e(r) were used to map the sequences necessary for normal expression. All of the sequences necessary for normal e(r) expression mapped to a 2,618 bp fragment that included the transcribed region plus 787 bp upstream of the start of transcription. The two introns of e(r) were shown not to contain transcription control sequences. These studies also mapped a transcription enhancer to a 5' region from -338 to -787 and a transcription silencer to a 5' region from -45 to -338. Along with the transgene study, deletions caused by P-element excision, exclusively located in the control region of e(r) were isolated and analyzed to determine effect on gene activity. The further refined region was then used with the EvoPrinter program, which .uses the 12 other Drosophila species as a comparison to determine any conservation of these sequences and TESS which uses input sequence to look for possible transcription factor binding sites.