Female clones created from the blood of male mice

Scientists in Japan have successfully created female clones from the blood of male mice using a technique that involves removing the Y chromosome. This process, known as sex reversal, was achieved through the use of CRISPR gene editing. The researchers inserted DNA from the male mouse's blood cells into mouse egg cells that had their DNA removed, a technique called somatic cell nuclear transfer.

Some of these embryos were treated with the CRISPR-based tool called Y-CUT, which reliably removed the Y chromosome from male mouse embryos. After transferring these embryos to surrogate female mice, all the resulting offspring were female clones genetically identical to the father, except for lacking the Y chromosome. The clones were found to be healthy and fertile, capable of producing offspring that were also healthy.

This method of dual-sex cloning could potentially be useful for conserving animals nearing extinction, as it could help revive species with only a single male or a few individuals remaining. However, there are concerns regarding the fertility of XO female mice in many other species and potential ethical issues associated with producing Y-deleted animals.

Despite these concerns, researchers believe that the technique could be valuable for frozen tissue samples from endangered or extinct species.