国内精品一区二区三区最新_不卡一区二区在线_另类重口100页在线播放_精品中文字幕一区在线

This picture released on Monday by Japanese natural science research center Riken in Kobe, Hyogo prefecture, shows a mouse(left) cloned by a new technology using a dead cell of a mouse that had been preserved at -20c. [Agencies via China Daily]

Japanese scientists have cloned mice whose bodies were frozen for as long 16 years and said on Monday it may be possible to use the technique to resurrect mammoths and other extinct species.

Mouse cloning expert Teruhiko Wakayama and colleagues at the Center for Developmental Biology, at Japan's Riken research institute in Yokohama, managed to clone the mice even though their cells had burst.

"Thus, nuclear transfer techniques could be used to 'resurrect' animals or maintain valuable genomic stocks from tissues frozen for prolonged periods without any cryopreservation," their findings were published in the Proceedings of the National Academy of Sciences in the United States.

A mouse used for cloning had been preserved at - 20 C, a temperature similar to frozen ground.

Wakayama's team used the classic nuclear transfer technique to make their mouse clones. This involves taking the nucleus out of an egg cell and replacing it with the nucleus of an ordinary cell from the animal to be cloned.

When done with the right chemical or electric trigger, this starts the egg dividing as if it had been fertilized by a sperm.

"Cloning animals by nuclear transfer provides an opportunity to preserve endangered mammalian species," they wrote.

"However, it has been suggested that the 'resurrection' of frozen extinct species (such as the woolly mammoth) is impracticable, as no live cells are available, and the genomic material that remains is inevitably degraded," they said.