Scientists in China breed healthy mice from two females

Scientists in China breed healthy mice from two females

A team of researchers has produced viable offspring from same-sex pairs of mice, using a novel technology that involves stem cells altered to remove certain genes.

Study author Qi Zhou, a developmental biologist, said their findings showed "a new and clear way to produce offspring between same-sex mammals".

To generate mouse pups from two male parents, the researchers had to delete seven imprinted regions.

Offspring were created from two male mice at the same time, but they did not survive.

This field of research treads on tricky ethical ground, with previous studies involving genetic editing and novel methods of reproduction prompting fears about the implications if similar processes were eventually applied to humans.

Using two sets of female mice DNA, with gene manipulations, the scientists produced 29 babies from 210 embryos, which lived to adulthood and reproduced normally.

Another view of a healthy adult bimaternal mouse, born to two mothers, with offspring of her own.

The key to success in the new study, say the researchers, were the haploid embryonic stem cells.

Chinese researchers have wowed the science world by breeding healthy mice with two mothers that went on to have normal pups of their own.

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HEALTHY mice have been bred from two mums and gone on to have normal pups of their own.

"Most people accept that genetically engineering humans is morally unconscionable, and doing the same thing to mice using stem-cell technology is just as reprehensible - it will not solve reproductive problems but will lead to misery for intelligent, sensitive beings". The scientists removed three imprinted regions from the DNA of a female ESC and injected them into the egg of a female partner to produce offspring from two moms.

"We found in this study that haploid ESCs were more similar to primordial germ cells, the precursors of eggs and sperm", according to co-senior author Hu Baoyang of CAS.

Co-author Wei Li said researchers would need to identify problematic imprinted genes that were unique to each species.

Then CRISPR-Cas9 gene editing - which uses DNA and RNA sequences culled from bacteria to pinpoint and delete human genes - turns off the genes that tell the remaining cells to be female, encouraging the egg to behave like sperm. These embryos were transferred along with placental material to surrogate mothers, who carried them to term.

The researchers in China have noted that there are still obstacles in achieving their feat with other mammals.

The team concentrated on roughly 100 genes that are activated when they come from both parents, but rely on each other for correct development. "However, the generated mice still showed defective features, and the method itself is very impractical and hard to use", said Zhou.

"We saw that the defects in bimaternal mice can be eliminated and that bipaternal reproduction barriers in mammals can also be crossed through imprinting modification".

"Sorry, chaps, you're obsolete": that may as well have been the headline of an announcement that gripped the research community on Thursday, as the birth was revealed of the world's first mammal born to two mothers.

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