Novel sex-determination mechanism revealed in mammals
The Sox9 gene is upregulated in the absence of sex-determining Y chromosome and Sry gene in Amami spiny rat.
In mammals, the distinction between male and female at the chromosomal level is due to the X and Y chromosomes. Typically, females have two X chromosomes (XX) while males have an X and a Y chromosome (XY). The Sry gene on the Y chromosome triggers the formation of the testes. However, there exist a handful of rodent species in which the Y chromosome has disappeared, taking with it the Sry gene. The mechanism by which testes development occurs in these species is not fully understood, and is subject to much research.
A team of researchers led by Professor Asato Kuroiwa at Hokkaido University has uncovered the genetic basis for sexual differentiation in the Amami spiny rat, one of the species the lacks a Y chromosome and the Sry gene. Their discoveries were published in the journal Proceedings of the National Academy of Sciences.
For more details, please see the press release by Hokkaido University
Miho Terao, Yuya Ogawa, et al. Turnover of mammal sex chromosomes in the Sry-deficient Amami spiny rat is due to male-specific upregulation of Sox9. Proceedings of the National Academies of Sciences. November 28, 2022.