Researchers from Japan and Russia say they have inserted cell nuclei from a woolly mammoth into the eggs of mice, and have confirmed signs of biological activities toward the early stages of cell division.
Scientists from Japan's Kindai University and others recovered cells from a young mammoth in relatively good condition from remains found in permafrost in Russia's Sakha Republic in 2010. The creature is believed to have lived about 28,000 years ago.
They introduced nuclei from the cells into about 40 mouse eggs.
The researchers say the mammoth's genes began to function in half of the eggs, causing a special protein to accumulate. They say they observed structures that form before cells divide in five of the eggs.
While the cells did not enter the stage of nuclear division, the scientists say the activity they observed confirms for the first time that the genes of frozen mammoth may remain active.
The scientists say they want to find a way to bring the extinct species back to life by studying the reconstruction of cells from genetic information, along with cloning technology.
Kei Miyamoto of Kindai University's genetic engineering department said finding that 28,000-year-old cell nuclei maintain some of their functions is a major discovery. But he said there are many technological and ethical challenges to be addressed.
The findings were published on Monday in the electronic version of the British science journal, Scientific Reports.