Scientists Successfully Clone Frozen Mice
Japanese scientists said on Monday they have created clones from the bodies of mice that have been frozen for 16 years.
The researchers said it might even be possible to use the technique to resurrect mammoths and other extinct species.
Teruhiko Wakayama and colleagues at the Center for Developmental Biology, at Japan’s RIKEN research institute in Yokohama, were able to clone the mice even though their cells had burst.
The team wrote: “Thus, nuclear transfer techniques could be used to ‘resurrect’ animals or maintain valuable genomic stocks from tissues frozen for prolonged periods without any cryopreservation.”
Wakayama and his team created the mouse clones using the classic nuclear transfer technique that 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.
With the right chemical or electric trigger, the egg will begin dividing as if a sperm had fertilized it.
“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.”
The researchers used mice whose cells were indisputably damaged from many years of being frozen. Freezing causes cells to burst and can damage the DNA inside. Chemicals called cryoprotectants can prevent this but they must be used before the cells are frozen.
Animals such as sheep, pigs, cattle, mice and dogs have been successfully cloned. Livestock breeders want to use cloning to start elite herds of desirable animals, and doctors want to use cloning technology in human medicine.
Several of the successful clones since Dolly the sheep was born in 1996 were created by a method where the nucleus of a cell has been removed, placed in an empty egg and kick-started into replicating by chemicals or electricity.
But Australian researchers used a different technique when cloning a pig in 2001 from cells that had been frozen for two years. The Adelaide-based team said its cloning method differed from the Dolly approach in important respects.
“There is hope in bringing Ted Williams back, after all,” said cloning and stem cell expert John Gearhart of the University of Pennsylvania. The family of Williams, the Boston Red Sox hitter, had his body frozen by cryogenics firm Alcor after he died in 2002.
Gearhart suggested the study might soon stimulate the small industry of freezing parts of us before we die to bring us back in the future.
Last year, Russian scientists discovered the body of a baby mammoth frozen in the Arctic Yamalo-Nenetsk region for as long as 40,000 years.
Scientists would most likely to try to clone an extinct Mammoth, as many of the animals have been found preserved in ice.
“It remains to be shown whether nuclei can be collected from whole bodies frozen without cryoprotectants and whether they will be viable for use in generating offspring following nuclear transfer,” Wakayama’s team wrote.
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