Men, your gender just took a hit in the animal kingdom. Scientists report they've created mice by using two genetic moms--and no dad, leaving some to wonder whether all-female human reproduction may someday be possible. The achievement is reported in Thursday's issue of the journal
Nature
by Tomohiro Kono of the Tokyo University of Agriculture in Japan, with colleagues there and in Korea. They say they produced two mice, one of which grew to maturity and gave birth. Kono said this mouse, named "Kaguya" after a Japanese fairy tale character, appears to be perfectly healthy.
Kono, in an e-mail, said the procedure might be useful with animals for agricultural and scientific purposes. Lab experiments in producing mice from all-female DNA had previously produced embryos and fetuses but no successful births. When asked if he saw any reason to produce human babies this way, he dismissed the question as "senseless."
Some experts say that although the
Nature
study focuses on single-sex reproduction, it also highlights why it may be exceedingly difficult to produce a human baby with genetic material from only one sex. Scientists say some mammal genes inherited from the father behave differently in the embryo than if they came from the mother, and that paternal activity pattern is needed for normal embryo development. Relatively few genes act in that way, and they are said to be "imprinted." In some cases these genes are active only if inherited from the father, not the mother, and in other cases it's the other way around.
For the study described in
Nature,
the researchers got around the need for male-derived DNA by turning to mutant mice. The female mice were missing a chunk of DNA, and as a result two of their genes would behave in an embryo as if they'd come from a male. What's more, the scientists took this mutated DNA from the egg cells of newborns, because at such a young age the DNA hasn't yet taken on the full "female" pattern of imprinting seen in mature eggs. That DNA was combined with genes from ordinary female mice to make reconstructed eggs. But only two of 457 such eggs produced living mice.
The process might be useful in producing stem cells, however. Some researchers hope that by stimulating unfertilized human eggs to develop into what they call "parthenotes," they can harvest stem cells without destroying ordinary embryos. Researchers hope stem cells can be used to treat a variety of diseases. Kent Vrana, a researcher at Pennsylvania State University who is studying the unfertilized-egg approach, said the
Nature
study is encouraging for that technology. If a normal, fertile mouse can be produced without a father's DNA, he said, that gives hope that stem cells from a similar process would be normal as well. (Associated Press)
