SEPARATE CIS-REGULATORY SEQUENCES CONTROL EXPRESSION OF SERENDIPITY-BETA AND JANUS-A, 2 IMMEDIATELY ADJACENT DROSOPHILA GENES

The genes janus (jan) A and B, and serendipity (sry) beta and delta ar e two pairs of duplicated genes that are adjacent to each other on the third chromosome of Drosophila melanogaster. The jan A and sry beta g enes are expressed throughout development in both males and females. T hey are transcribed in opposite orientations from start sites separate d by only 173 bp of DNA. We report here the complete sequence of the j an A and B genes in Drosophila pseudoobscura, a species distantly rela ted to D. melanogaster in which the overall organization of the sry be ta, jan A and jan B genes is identical to that in D. melanogaster. Seq uence comparison of the jan A-sry beta intergenic region and 5'-transc ribed domain of each gene between D. melanogaster and D. pseudoobscura reveals short stretches of conserved sequences that may correspond to cis-acting regulator elements. In order to test the possibility that some cis-acting regulatory sequences are shared by the two genes, we c arried out a deletion analysis of the jan A/sry beta intergenic region in D. melanogaster using transgenic lacZ fusion genes. Our results sh ow that sry beta cis-acting sequences are located in the(-117; + 137) 5'-region of the gene and that jan A cis-regulatory sequences are incl uded in the (-56; + 151) 5'-domain of this gene. Together these data i ndicate that in spite of the physical proximity of the jan A and sry b eta genes, their transcription is regulated by separate cis-acting seq uences.