FIGURE 1.

Extensive sex-specific alternative splicing in Drosophila melanogaster. (A) Distribution of sex-specific differences in alternative splicing. (Left panel) Distribution of the 986 sex-specific regulated splice junctions (sjncs), between sjncs annotated as alternative (alt) or constitutive (const). (Middle panel) Distribution of gene expression (GE) and alternative splicing (AS) changes between male and female flies. (Right panel) Distribution of classes of alternative splicing events for all the sjncs represented on the array (black bars) and those sex-differentially regulated (gray bars). (B) Alternative splicing of a cassette exon in the 5′ UTR of extra bases (exba) affects translational efficiency in cell culture. The 5′ UTRs of exba, including the endogenous translational start (ATG), were cloned in frame with the firefly luciferase gene in a Cu²⁺ inducible Drosophila vector (top panel). Luciferase activity (normalized to the activity of cotransfected Renilla) for three independent experiments is represented for different amounts of transfected plasmids (left panel). Black bars correspond to the longer and gray bars to the shorter isoforms of exba 5′ UTRs, respectively. The levels of 5′ UTR-exba-luc mRNA from the same experiments were quantified by real-time PCR and presented as relative amounts (right panel).