Fig. 2. Gene structure and expression. (A) achi and vis are tandem duplications. The intron/exon structure is shown together with the alternative splice products determined from completely sequencing the following cDNAs: achi-class 1 LD25085,GM01582; achi-class 2 LP02076; vis-class 1 SD08875, SD01238. vis-class 2 intron/exon structure was determined by sequencing a subclone of the ORF RT-PCR shown in D. Translation is initiated in exon3 (arrow) and terminates in exon10 (asterisk). (B) RT-PCR analysis with primers (f1 and r3) common to both achi and vis indicates expression throughout development. A similar result was obtained with primers specific for achi. The RP49 control gave approximately equal levels with RNAs from all the different developmental time points. (C) Sex-specific splice differences of achi/vis. Class 2 products predominate in testes (lane 1) whilst class 1 products (lane 2) predominate in ovaries (primers: f3 and r2). Similar results are seen comparing male and female whole fly RNA (not shown). (D) Class 2 transcripts are testes specific. Lane 1: testes; lane 2: male gonadectomised carcass and lane 3: adult females (achi/vis ORF primers).