Figure 7.

Model for sex determination in Aedes aegypti. In male embryos a male-determining factor (M) inhibits the function of an SR-F protein required for the female-specific splicing of exon 5b and activates the function of an SR-M protein required for the male-specific repression of exon 5a. It is also conceivable that the M could directly control the splicing of Aeadsx exon 5a. In any case, the result is the skipping of both female-specific exons and only a male-specific product of dsx gene is produced in male embryos and this product induces the male development. In female embryos the absence of the M leads to the default splicing of female-specific exons 5a and 5b and to the activation of the SR-F factor which in turn regulates the female-specific splicing of exon 5b. As a result two female-specific DSX proteins are produced that induce female development. Alternative male-specific and female-specific exons are represented as blue boxes and pink boxes, respectively. Green dot represent NvdsxRE and TRA-2-ISS elements. White dot represents TRA/TRA-2 binding sites.

Salvemini et al. BMC Evolutionary Biology 2011 11:41   doi:10.1186/1471-2148-11-41
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