The mouse Sry locus harbors a cryptic exon that is essential for male sex determination

Sex of mice determined by overlooked gene fragment

29 March 2021

A previously overlooked part of the sex-determining gene Sry is responsible kicking off the series of events that leads to the development of male mice.

For more than 30 years, the gene Sry on the male Y chromosome has been known to determine the sex of mammalian offspring. But it was considered to have only a single exon — a section of DNA within a gene that codes for a protein.

Now, a team of five researchers at Osaka University and a collaborator have found that Sry in mice actually has two exons, and that the newly discovered exon is the key to the development of male offspring. They found that mice having XY chromosomes would develop as females if they lacked the exon and, conversely, mice having two X chromosomes would become males if they possessed the exon.

While humans lack the newly discovered exon, this finding could have implications for how human Sry functions.

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References

1. Science 370, 121–124 (2020). doi: 10.1126/science.abb6430