Figure 1. tra gene organization and sex-specific transcripts in C. hominivorax (Ch), C. macellaria (Cm) and L. sericata (Ls).

tra genes of all 3 species consist of 4 exons (red boxes) and one male specific exon (blue box). Introns are shown with a black line. All exons and introns are drawn to scale with intron 1 interrupted as it significantly larger than the other introns. 5′ and 3′ untranslated regions are shown in black boxes. Exon and intron sizes in bp are shown. Male and female transcripts are represented below the gene. Vertical lines with asterisks indicate the relative locations of in-frame stop codons in the male exons. Arrows indicate the primer pairs used for RT-PCR. A single predominant product was obtained from each sex (arrows).