Y Chromosomes are considered to be the "male gene," found in the process of male reproduction; but researchers found a way to make reproduction possible without its presence.
The team found baby mice could be produced "using germ cells from males with the Y chromosome contribution limited to only two genes," a University of of Hawaii at Manoa news release reported.
"Does this mean that the Y chromosome (or most of it) is no longer needed? Yes, given our current technological advances in assisted reproductive technologies," Monika A. Ward, Associate Professor at the Institute for Biogenesis Research, John A. Burns School of Medicine, said.
The team identified minimum amount of Y chromosomes needed to produce offspring that were healthy and fertile.
The researchers studied transgenic male mice that had on two Y chromosomes called Sry and Eif2s3y. The mice were considered infertile because the germ cells that should have been sperm never fully matured (meiotic and postmeiotic arrests). The researchers were eventually able to find some healthy and usable cells. A researcher gathered up the immature spermatids and performed a process called called "round spermatid injection (ROSI)" to fertilize oocytes.
Once the embryos developed they were transmitted into surrogate mother mice and many healthy offspring were produced.
The male mice still did not have a reproductive rate as high as sexually healthy mice, so the researchers replaced Sry with the sex reversal factor Sxrb, which adds to chromosomes. This gave the offspring rate a two-fold boost.
"Most of the mouse Y chromosome genes are necessary for normal fertilization," Ward said. "However, when it comes to assisted reproduction, our mouse study proves that the Y chromosome contribution can be brought to a bare minimum. It may be possible to eliminate the mouse Y chromosome altogether if appropriate replacements are made for those two genes."
There is a lot to be done in terms of testing the safety and effectiveness of the process, but researchers hope it will one day help "infertile" men reproduce.
