Conserved Sex-chromosome-associated Nucleotide Sequences in Eukaryotes

Abstract

Sexual differentiation is probably the most important aspect of the many processes of differentiation that underlie the development of the adult organism. In principle, it is likely that the determination of primary sex will involve mechanisms related to those that control other aspects of differentiation. In our work on the structure of sex-determining chromosomes in primitive vertebrates, we have identified and recovered a repeated DNA from snakes that appears as a satellite fraction in female DNA. This satellite is interspersed with other more complex DNA throughout the length of the sex-determining W chromosome, and both are recovered together by ultracentrifugation in heavy-metal-containing isopycnic gradients. It is these more complex sequence elements that we believe are responsible for the phenomena described in this paper.