March 12 (UPI) -- Researchers in Japan have activated woolly mammoth cell nuclei transplanted in mouse cells.
Scientists extracted cell nuclei from the bone marrow and muscle of a well-preserved, 28,000-year-old mammoth recovered from the Siberian permafrost in 2011. In the lab, researchers implanted the nuclei inside mouse oocytes, ovary cells that can divide to form egg cells.
A handful of the mouse oocytes hosted biological activity, the biochemical reactions that precede cell division.
Scientists observed a "pronucleus-like structure budded ... from a mammoth nucleus." Their observations also suggested the injection of mammoth nuclei triggered DNA repair machinery in mouse oocytes.
Researchers described the activity this week in the journal Scientific Reports.
The breakthrough marks a "significant step toward bringing mammoths back from the dead," Kei Miyamoto, a member of the research team at Kindai University, told the Nikkei Asian Review.
None of the mouse cells implanted with mammoth nuclei performed cell division, a key step in reanimating the long-extinct mammoth.
"We want to move our study forward to the stage of cell division," said Miyamoto. "We still have a long way to go."
Miyamoto and his colleagues are working with researchers in Russia to bring mammoths back to life using cloning technology called somatic cell nuclear transfer.