Researchers ‘Revive’ Woolly Mammoth Cell Nuclei

Friday, March 15, 2019

The 28,140-year-old mammoth calf Yuka. Image credit: Cyclonaut / CC BY-SA 4.0.

In 2010, the 28,140-year-old partial carcass of a woolly mammoth (Mammuthus primigenius), nicknamed ‘Yuka,’ was found in Siberian permafrost. Now a team of scientists in Japan has recovered the less-damaged nucleus-like structures from Yuka’s remains and visualized their dynamics in living mouse eggs (oocytes) after a procedure called nuclear transfer.

Yuka was discovered in the summer of 2010 in a cave near the village of Yukagir in the Republic of Sakha.

The young female specimen is the most intact and well-preserved woolly mammoth ever found.

“In the study, we obtained bone marrow and muscle tissue from Yuka and attempted to decipher various biological information and to restore cell nuclear function,” said team leader Dr. Akira Iritani of Kindai University and colleagues.

“First, we compared the genetic information of ‘Yuka’ with African elephants and confirmed the characteristic single base substitution and amino acid substitution possessed by mammoths.”

Yamagata et al succeeded in observing the signs of the biological activity of 28,140-year-old mammoth nuclei in mouse oocytes. In this image, proteins that form chromosomes (red) and proteins that form dividing spindles (green) gather around a mammoth cell nucleus (upper right) in the mouse oocyte. Image credit: Yamagata et al, doi: 10.1038/s41598-019-40546-1.

The researchers performed proteomic analysis of the mammoth remains and demonstrated the presence of nucleus-like structures in the samples.

They then extracted the cell nuclei from the remains and transplanted them into the mouse oocytes.

“The mass spectroscopy analysis of the protein preservation state showed that the muscle tissue of ‘Yuka’ was preserved in a relatively good state and the components of cell nuclei were present,” they explained.

“We then extracted the nuclei from the muscle tissue, injected them into the mouse oocytes using a micromanipulator, and observed the reaction after nuclear transfer using a disk-type confocal laser microscope.”

“This resulted in some mammoth cell nuclei beginning to take up mouse cell nuclear proteins in the mouse oocytes, and cells shaped as those do before division were observed.”

“Furthermore, a part of the mammoth nuclei started to form a partial nucleus-like structure, and this newly formed structure was eventually incorporated into the cell nucleus of the mouse oocyte.”

“This research is a pioneering achievement that demonstrates for the first time in the world that some well-preserved mammoth fossils retain cell nuclei that can be reconstituted in the currently living embryos,” the study authors said.

The results appear in the journal Scientific Reports.


Kazuo Yamagata et al. 2019. Signs of biological activities of 28,000-year-old mammoth nuclei in mouse oocytes visualized by live-cell imaging. Scientific Reports 9, article number: 4050; doi: 10.1038/s41598-019-40546-1