Scientists Revive Woolly Mammoth Cells 28,000 Years Old in Mice

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Yuka-Mammoth-Feature

The dream of resurrecting species like the woolly mammoth via genetic engineering is old enough for me to remember reading articles about it in school 30 years ago. We may never be able to recover enough virgin genetic material from an intact woolly mammoth to make this approach feasible, but scientists working on the remains of the frozen mammoth known as Yuka have nevertheless taken an incredible step by demonstrating that at least some cellular functions may remain intact after nearly 30,000 years.

Yuka, discovered in 2010, is a juvenile woolly mammoth, considered the most intact and best preserved mammoth ever discovered. This was an essential element of the researchers' efforts: previous tests conducted in 2009 with a less well preserved specimen, but younger at 15 000 years, did not yield any positive results.

To be clear: the scientists in question were do not able to bring Yuka's cells back to life. After removing 88 nuclei-like structures from Yuka cells, they injected these structures into mouse oocytes – eggs – to determine if they could become active again. Although the cells eventually failed to divide, they made perform some of the steps necessary for cell division, such as spindle assembly. This process of pin assembly ensures that the chromosomes are properly prepared to divide before the mother cell divides.

The fact that the cells could not divide completely is not surprising. The degree of genetic damage inside Yuka's body was enormous, and while the researchers were trying to find the least damaged cells possible, none of the chosen samples could be fully reactivated.

The research team was able to identify some biomarkers inside mammoth-labeled oocytes and create a report indicating how much the mammoth nuclei were damaged. They labeled this DNA damage (DDI) DNA with a DDI of 1.0x equivalent to the overall level of damage seen in fresh mouse sperm. The mammoth nuclear DDI varied greatly, ranging from a little over 1x to around 4x. A comparison of the most damaged and damaged kernels is presented below (f). We will talk about (i) below.

DDI-Index

Chart (i) shows how the DDI ratio changed after activation of oocyte cells. In most cases, the level of damage has increased over time. But in a few cases, the observed level of DDI has dropped, or at least considerably, for a short time. This indicates that DNA repair mechanisms in mouse oocytes could be activated in response to damaged nuclei. This does not mean that plugging a 30,000-year-old mammoth nucleus on a mouse egg will cause the appearance of a fully functional mammoth genome on the other side – but that indicates that the repair mechanisms inside the cell were active and try to sew double-strand breaks in the DNA. That means there was enough DNA, in at least a few cases, for the cell recognize that it was DNA at the beginning and to have an idea of ​​how to connect it.

As far as I know, it was the closest scientists who managed to bring back to life complex eukaryotic animal cells after tens of thousands of years on the ice. We have successfully restored dormant viruses found in the permafrost of thawed areas, but we have never been able to recover viable cells from a long-dead organism. To be clear, we again Viable cells have not been found today, and researchers admit that they have not yet solved the problem.

To sum up the problem in computer terms: we took an old MFM hard drive, connected it to a modern PC and observed that some of its mechanical components were still working when proper commands were sent. We even started a kind of "chkdsk" on the drive itself, although that failed in the context of the metaphor. What we not managed to do is start an operating system or retrieve its contents. This is a significant step forward and a fascinating discovery.

Featured Image courtesy of Wikipedia

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