6-BANDED, A NOVEL DROSOPHILA GENE, IS EXPRESSED IN 6 SEGMENTAL STRIPES DURING EMBRYONIC-DEVELOPMENT AND IN THE EYE IMAGINAL DISC

We have characterised a Drosophila P-element enhancer detector inserti on F125, which is expressed in the embryonic head and CNS as well as i n various third instar imaginal discs. In an attempt to identify the g ene with the equivalent expression pattern, we have characterised an a djacent gene. It encodes two novel conceptual proteins: Type I (1182 a mino acids) and Type II, representing a shorter form of 774 amino acid s truncated at both termini relative to Type I that is generated by al ternative splicing. Based on its embryonic expression pattern, the gen e was called six-banded (sba). Both splice forms are expressed in a un ique embryonic pattern: initially as 6, then 12 stripes during early s tages of embryonic development. Subsequently, expression is found in t he developing trachae and during larval development is restricted to t he eye imaginal disc where both transcripts are present immediately an terior to and behind the morphogenetic furrow, While sba expression in the eye antennal disc is mirrored by the expression of the adjacent F 125 P-element, other patterns reported by this enhancer detector are n ot mimicked by the sba gene suggesting that the expression of the P-el ement represents a 'composite' of the effects of nearby enhancers.