chematicpresentationofthegenomicorganizationandproposedproteinstructureofcsd.A:Genomicregionencompassing csd and the two closely linked genetic markers (marker 1 and 2). The genetic markers 1 and 2 are always heterozygous in females; this identifies the sex-determining locus. Exons are indicated by boxes and the deduced ORF is marked in yellow. The estimate of the transcript is indicated in nucleotides (nt), which represents just one allelic variant. No sex-specific differences were found among the transcripts. Predicted translational start and stop sites are indicated. B: The schematic presentation of the predicted domain structure of csd. The region rich in arginine/serine (RS domain) is marked in red, the hypervariable region that has different number of repeats in various alleles is shown in grey (HV) and the proline-rich region is marked in blue. The number of amino acids of the CSD protein varies between alleles as indicated.