91色情片

IT鈥橲 not as if they need any help to reproduce, but at last rabbits have joined the list of animals that have been cloned. Several groups tried but failed, until Jean-Paul Renard and his colleagues at the National Institute for Agricultural Research in Paris figured out a way (Nature Biotechnology, vol 20, p 366). The trick is in the timing of various steps, such as how long to expose the early embryos to certain chemicals and when to implant them in the womb. Even so, only four kits were born out of 371 cloned embryos transferred into host mothers. According to the scientists, cloned bunnies would be useful models of human disease, as they鈥檙e genetically more similar to us than are mice and rats.