We’ve heard some say that if you don’t want a baby girl, do not have sex close to ovulation. This asserts that the sperm with the Y chromosome, the one responsible in making male babies, swim faster. Therefore, you have a better chance of having a daughter if the sperm has to travel a long way to its destination which is the egg. While this tip has no scientific merit whatsoever, scientists have now found a way to make this “true, sort of.”
X and Y chromosomes aren’t just different sizes—the X is about three times longer than the Y—they also contain different genes. In the new study, scientists used these genetic differences to sort “male” mouse sperm from “female” sperm.
They zeroed in on a specific gene, called Toll-like receptor 7/8, which is expressed only in X-chromosome sperm and codes for two receptors on the sperm cell’s tail and midpiece. The scientists incubated mouse sperm in a mixture containing molecules that would bind to the receptors and activate them. The molecules slowed energy production in X-chromosome sperm while not affecting the Y-chromosome sperm at all, the team reports today in PLOS Biology.
To confirm their findings, the researchers staged sperm races. Many of the modified X sperm swam at less than half the speed of the Y sperm. And when researchers used only the faster Y sperm for in vitro fertilization, 90% of the mouse pups were born male. Separating out the slowest sperm produced litters that were 81% female.
Interesting research. What do you think?
(Image Credit: geralt/ Pixabay)