With a step closer to new invention, a team of Japanese researchers claimed on Monday that they have been successful in cloning dead mice that had been frozen for 16 years. This raises a possibility that woolly mammoths that walked the Earth thousands of years back could also be cloned. 

Once the animal tissue freezes, it is quite possible that the DNA inside the cell nuclei is adversely damaged due to bursting of the cell walls. This is the reason why most scientists had thought that it is quite impossible to get any good DNA from the thousands of frozen mammoths that are still assumed to be lying in the Siberian permafrost. 

However, the Japanese team found that DNA might be preserved through the high concentration of sugar in brain tissue. Following this, they explored the brains of the frozen mice in order to find some healthy DNA, which they did and then they put it into unfertilized live mouse eggs. 

 The resulting embryos were used to produce stem cells, which in turn produced more embryos. Finally, 13 mice were born. 

But cloning mammoths would of course be tougher as the temperatures of the frozen carcasses have varied a lot over the time phase of tens of thousands of years. Just in case a healthy DNA is discovered, then Asian elephants could be used for getting the eggs. Asian elephants are more closely related to mammoths than African elephants. 

Team leader Teruhiko Wakayama of the RIKEN Center for Developmental Biology in Kobe, Japan, told, "It would be very difficult, but our work suggests that it is no longer science fiction."