The daughter of two mothers. No, really!

Kaguya is a bit of a miracle: it is a young, rather cute little mouse that was brought into this world without the help of a male mouse. We're not talking about IVF, ICSI or other beginners stuff here: this girl is the first mammal without a father, as it's "Dad", japanese biologist Tomohiro Kono was able to use two eggs (= female haploid gametes) to create a new life. Not that it came easy: 457 eggs were reconstructed, 91 percent developed to blastocyst stage, 371 embryos were implanted into 26 female mice, 24 females became pregnant, 28 pups were born and only 2 were healthy.

Now, how does it work, so you can do it at home and impress your dinner guests?

You see, parthenogenesis (also known as virgin birth for you religious types out there) is not that uncommon in mammals: unfortunately does it never come to a birth of a living being. Mostly these activated gametes form into teratogenic tumours or just get spontaneously aborted, although plenty of other animals know how to do it. Can't be fun though. The reason that fusing two gametes of the same sex together doesn't produce a viable baby is a little trick of nature called "imprinting": when spermatic cells form, ca 30 genes are being permanently switched off, while the same happens for a different set of genes in eggs, so that when they fuse, they have the right set of genes active.

Tomohiro had the clever idea to genetically alter a mouse so that its eggs behaved more like sperms: by switching off a gene called H19 (which regulates IGF-2, a growth hormone) imprinting was suppressed as well, and voila: a female gamete happy (well, relatively) to fuse with a normal egg. By using two eggs, this is of course not a true parthogene: although Tomohiro called it a parthogenetic mouse in his paper, so he got a bit of an earbashing from his fellow biologists.

Unfortunately for all our e2 lesbians this will probably never work in humans, so I have to crush your dreams of homoparental kids.

You'll still need that bloke, sorry.

Source: "Dawn of a new parenthood", SP Westphal, New Scientist, 24.4.04, pp 8-10