"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.
Co-senior author Qi Zhou said: "This research shows us what's possible".
What they did: Sexual reproduction usually involves a sperm and an egg.
While some reptiles, amphibians, and fish can reproduce with one parent of the same sex, it's challenging for mammals to do the same even with the help of fertilization technology. In mammals, because certain maternal or paternal genes are shut off during germline development by a mechanism called genomic imprinting, offspring that don't receive genetic material from both a mother and a father might experience developmental abnormalities or might not be viable.
Just as impressively, the created mice were able to live to adulthood and have offspring of their own.
Publishing their results in the Cell Stem Cell journal, the researchers explained that they produced the mice by injecting stem cells from one mother into the eggs of the other.
One advantage of using haploid ESCs is that even before the problematic genes are knocked out, they contain less of the imprinting programming that ultimately causes maternal- or paternal-specific genes to be expressed.
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They also deleted a number of "imprinted" genes from these cells, since such genes normally depend on being paired with a corresponding male gene to work properly.
"We have made several findings in the past by combining reproduction and regeneration, so we tried to find out whether more normal mice with two female parents, or even mice with two male parents, could be produced using haploid embryonic stem cells with gene deletion".
But while the research will raise expectations that other animals could be produced from parents of the same sex, Dr. Ilic warns that it will be a long time before similar methods could be used to produce human babies from two mums or two dads.
A similar experiment using two male parents failed, however, the pups dying within days of being born.
These pups survived 48 hours after birth, but the researchers are planning to improve the process so that the bipaternal mice live to adulthood.
Right now, it's far too complicated, and not all of the offspring survived.
A team at the Chinese Academy of Sciences stunned geneticists by revealing they had effectively rewritten the rules of reproduction, and in the process discovered exactly why some animals, including humans, need to have sex. "The defects in bimaternal mice [shown in previous research] can be eliminated and bipaternal reproduction barriers in mammals can also be crossed".