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Cell nuclei from ancient woolly mammoth show signs of biological activity

In this image provided by Kindai University, red proteins that form chromosomes, and green proteins that form dividing spindles gather around a mammoth cell nucleus, upper right, in the egg of a mouse.

TOKYO -- Researchers from Japan and Russia observed biological activity when they transplanted cell nuclei from a woolly mammoth from the Siberian permafrost into the eggs of mice, moving a step closer to the goal of bringing the extinct mammal back to life.

The researchers, including members of Japan's Kindai University, extracted cell nuclei from the remains of a woolly mammoth calf named Yuka, found in the Sakha Republic of Russia's Far East in 2010 and estimated to be roughly 28,000 years old. When these nuclei were transplanted into the eggs of mice, the researchers were able to observe the early stages of cell division.

This photo provided by Kindai University shows the remains of the mammoth calf Yuka that researchers used to extract nuclei from muscle cells.

The team used nuclei from muscle cells that were in relatively good condition to examine whether they were still able to function upon transplantation. The cells contain DNA, and immediately before they divide, chromosomes are formed, which are then pulled by spindle fibers.

Researchers inserted 24 cell nuclei into the eggs of mice, and found that proteins that form chromosomes gathered around the cell nuclei in 21 of these eggs. In five of these eggs, the gathering of proteins that form the spindle was also observed. However, none of these cases resulted in full cell division. Researchers say there is a possibility that the division stopped because the DNA has been significantly damaged.

The research is part of a project at Kindai University to revive the woolly mammoth. Their goal is to transplant the cell nucleus of a mammoth into the egg of an elephant to create a fertilized egg with mammoth genes. This would then be transplanted into the uterus of an elephant to give birth to a mammoth.

Satoshi Kurosaka of the Institute of Advanced Technology at Kindai University, who took part in the research, commented, "We hope to find a mammoth that has been better preserved."

The team's research was published online in the British science journal Scientific Reports.

(Japanese original by Koki Matsumoto, Science & Environment News Department)

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