A handful of pieces of woolly mammoth cells of 280000 years have recently been "woken up" for a short time in a new experiment, but the cloning of the glacial beasts is still a long way off.
The researchers extracted cells from Yuka, a woolly mammoth mummy ( Mammuthus primigenius ) whose remains were discovered in the Siberian permafrost in 2011. Thus, scientists recovered the least damaged nuclei (structures that they contain genetic material
Initially, this maneuver "activated" the mammoth chromosomes, like several biological reactions that take place before the cell division actually takes place inside the mouse cell. But these reactions soon stopped, probably in part, because the mammoth DNA was severely damaged after spending 28,000 years buried in permafrost, the researchers said. [In Photos: Mummified Woolly Mammoth Discovered]
Why did researchers put Mammoth DNA in mouse eggs? dealing with an egg's ability to replicate DNA and divide into multiple cells.
"Eggs have all the living cellular mechanisms they could It would be necessary to correct errors and correct the damage that occurred inside the cores, "said Beth Shapiro, professor of ecology and evolutionary biology at the University of California, Santa Cruz, who is not been involved in the study. "[The scientists] basically froze [the mammoth nuclei] in there and said," Okay, cellular machinery, do your thing ".
And, at first, the cellular machinery tried to fix the damaged DNA at # 39. "Inside the chromosomes and piece together the broken pieces, said Shapiro." But [the egg] can only do so much, "he told Live Science." When nuclei are severely damaged, then it is not possible to reconstitute that you would need to do to bring it back to life. "
As a result, none of the mouse's mammoth hybrid cells entered cell division, a necessary step to create an embryo and, perhaps one day, clone a mammoth.
" The results presented here clearly show the in fact impossibility of cloning the mammoth with current NT technology [nuclear-transfer]"the researchers wrote in the study, published online March 1
As the mammoth died, its DNA began to degrade. This is because the bacteria from the intestine of the mammoth and the surrounding environment began to trample the cells of the dead mammoths. The ultraviolet (UV) radiation of the sun has also destroyed most of the genetic material and these processes have continued for eons. As a result, DNA fragments in the nucleus that have survived to date can only be tens to hundreds of long bases, rather than the millions found in the DNA of modern elephants, Shapiro said.
However, the study is still exciting, said Rebekah Rogers, an assistant professor of bioinformatics at the University of North Carolina at Charlotte, who was not involved in the research. For example, if researchers can also insert small pieces of mammoth DNA into a cell line, this could reveal what DNA does in a living creature, he said. [Mammoth Resurrection: 11 Hurdles to Bringing Back an Ice Age Beast]
In the study, the researchers added that "our approach opens the way to assess the biological activities of nuclei in extinct animal species".
However, Rogers said he would like to see more evidence that the mammoth actually became the mouse egg. "It is possible that you may have a highly modified mouse chromosome or potentially some other DNA contamination," he said. "They have this extraordinary statement that they put mammoths in a mouse [egg]. I would very much like to see a lot of evidence for this type of statement."
Other research groups are also trying to resurrect the mammoth, using different technology. George Church, a Harvard University geneticist and the Massachusetts Institute of Technology who heads the Harvard Woolly Mammoth Revival team, is following an approach. He is using CRISPR – a tool that can modify the bases of DNA, or letters – to insert woolly mammoth genes into the DNA of Asian elephants, which are closely related to extinct animals.
"They are not trying to revive a mammoth genome," said Shapiro. "They are trying to create one by modifying an elephant genome, so they could have a living cell as a final product."
Finding the mammals of the ice age is controversial however. Many environmentalists argue that resources should be spent on animals that are currently threatened or endangered, rather than animals that died long ago.
Originally published on Live Science .