Creating Mice Offsprings With Just Two Male Genes

Researchers have discovered that it would be possible for a male mouse to create healthy babies (using assisted reproduction) with just two genes from the Y-chromosome. They also observed that male mice missing only seven genes from their Y-chromosomes were still able to produce healthy offspring. This extraordinary find could bring researchers a step closer in creating mice that can become fathers without any help from the Y-chromosome. It can also shed some light for human infertility, because the study indicates that the assisted reproduction technique used in the mice might prove to be safer than the current methods used in humans.

 Usually, an embryo without a Y-chromosome turns into a female, but biologist have wondered whether the entire chromosome is really needed to create a healthy male offspring. Interestingly enough, studies have shown that a single gene from the Y-chromosome called Sry is all that is needed to create an infertile but anatomically correct male mouse. A team of scientist led by Monika Ward of the University of Hawaii in Honolulu, have found that by inserting two Y-chromosome genes, Sry and Eif2s3y, into male mice missing a Y-chromosome, they are still able to produce sperm-cell precursors known as round spermatids. These mice were then used to undergo reproduction. Scientists injected the round spermatids into the eggs, using a technique called round spermatid injection, also known as ROSI. Some of the eggs developed into embryos and were then implanted in the wombs of female mice. As a result, 9% of the pregnant mice had successful pregnancies, in comparison with 26% of births from mice with a full Y-chromosome.

ROSI is a procedure used to help infertile men whose testes are not able to produce normal sperm but many fertility specialists have fears that the use of immature round spermatids would result in genetically defective offspring. This study offers some support to the procedure since the study shows that normal offspring were obtained from using the ROSI with just the two Y-chromosome genes. This discovery is important in helping infertile men with defective Y-chromosomes. Ward is hoping to find genes on other chromosomes that interact with the Y-chromosome genes, that when activated, may eliminate the need for the original Y chromosome gene. This can ultimately help change the process of assisted reproduction for the future, enabling couples with certain circumstances, to have kids. 

Original article: http://www.nature.com/news/mice-with-just-two-male-genes-father-babies-1.14219