The most predictable mammalian chromosome has a wild side. The X chromosome — long thought to be pretty much the same across mammals — actually harbors a collection of naughty genes that differ between species and switch on in the testicles.
The genes could play starring roles in sperm production and in the evolution of mammalian species.
“It’s very surprising,” says Jacob Mueller of MIT’s Whitehead Institute for Biomedical Research. “You have this everyday collection of genes that everybody is familiar with, and then you have this mysterious side.”
