P ELEMENT SEQUENCES CAN COMPENSATE FOR A DELETION OF THE YELLOW REGULATORY REGION IN DROSOPHILA-MELANOGASTER

The effects of interactions between P element and yellow regulatory se quences on the control of yellow expression were studied. The mutation s used in the analysis lack a segment of upstream sequence that extend s from position -146 bp to -70 bp, relative to the transcription start site of the yellow gene. This sequence has been found to be necessary for the function of the yellow promoter. The insertion of one or two P element copies at position -69 bp compensates for the deletion in th e regulatory region and restores yellow, expression. After mobilizatio n of the P element, new phenotypes were selected and molecularly chara cterized. Two regions in the 5' part of the P element, from 23 bp to 7 1 bp and from 82 bp to 108 bp, can each partially compensate for the y ellow deletion. In addition, deletion derivatives of the P element wer e themselves able to activate yellow transcription. All such P element s retain at least 108 bp of sequence at the 5' end and 15-17 bp at the 3' end. Thus, the region of the P element from 23 bp to 108 bp contai ns cis-regulatory elements that can influence the transcription of nei ghboring genes.