The Sis A and Sis b genes are found on the X cromosome and encode transcriptional activators that control expression of the Sxl gene. Dpn, a repressor of Sxl, is encoded by a gene on an autosome. The ratio of activators to repressors differs in the two sexes, and the 2: 1 ratio between the activators and repressors in female activates the transcription of Sxl gene(sex-lethal gene) from the Pe promoter. The translational product is called early Sxl protein B Regulation of the alternative splicing of sex-determinant mRNAs leads to different sexes. In females. the early Sxl protein acts as the splicing repressor to ensure the production of the mature Sxl mRNA transcribed from another promoter called Pm, leading to the functional Sxl protein(2). Sxl protein also acts as the splicing repressor of Tra pre-mRNA. Leading to the production of the functional Tra protein(2). Tra protein, together with the Tra-2, acts as the splicing activator for dsx double sex) pre-mRNA Splicing, resulting in the production of one isoform of DsX protein that represses male gene expression and activated female gene expression(2) As a result, female development is established. In males, without Sxl proteins Pre-mRNA of Sxl gene from the Pm promoter and tra gene could not be spliced to produce functional Sxl protein nor the Tra protein. Thus, pre-mRNA of dsx gene is spliced in another way to give a dsx protein isoform that represses female genes Therefore, male development is established(3) Score plot The average score is 97.35 9分--9-9The Sis A and Sis B genes are found on the X cromosome and encode transcriptional activators that control expression of the Sxl gene. Dpn, a repressor of Sxl, is encoded by a gene on an autosome. The ratio of activators to repressors differs in the two sexes, and the 2:1 ratio between the activators and repressors in female activates the transcription of Sxl gene (sex-lethal gene) from the Pe promoter. The translational product is called early Sxl protein. 6’ B. Regulation of the alternative splicing of sex-determinant mRNAs leads to different sexes. In females, the early Sxl protein acts as the splicing repressor to ensure the production of the mature Sxl mRNA transcribed from another promoter called Pm, leading to the functional Sxl protein (2’). Sxl protein also acts as the splicing repressor of Tra pre-mRNA. Leading to the production of the functional Tra protein (2’). Tra protein, together with the Tra-2, acts as the splicing activator for dsx (double sex) pre-mRNA splicing, resulting in the production of one isoform of Dsx protein that represses male gene expression and activated female gene expression (2’). As a result, female development is established. In males, without Sxl proteins, Pre-mRNA of Sxl gene from the Pm promoter and tra gene could not be spliced to produce functional Sxl protein nor the Tra protein. Thus, pre-mRNA of dsx gene is spliced in another way to give a Dsx protein isoform that represses female genes. Therefore, male development is established (3’). 0 5 10 15 20 25 <30 30 ~50 50 ~70 70 ~80 80 ~90 90 ~100 100 ~110 110 ~120 120 ~130 Score Plot The average score is 97.35