miércoles, 25 de marzo de 2015

Scientists Successfully Insert Woolly Mammoth DNA Into Elephant Genome



Photo credit: AuntSpray/ Shutterstock
In true "Jurassic Park" style, scientists at Harvard University have successfully managed to insert genes from the woolly mammoth into the genome of an elephant. While this may represent significant progress in the field, lead researcher George Church has reportedly played down claims that the work brings us closer to recreating these iconic animals.

Woolly mammoths (Mammuthus primignius) may have appeared more than 400,000 years ago during the middle Pleistocene, but they actually didn’t die out all that long ago. Alongside most other large mammal species residing in the Northern Hemisphere, they disappeared from most of their range across mainland Eurasia and North America about 10,000 years ago, but a small population of some 500-1,000 individuals survived on Wrangel Island in the Arctic Ocean for a further 6,000 years.



Since many resided in frozen parts of the world, when they died their bodies sometimes became encased in permafrost, which largely shielded them from decomposition and the hungry mouths of predators and scavengers. This has meant that some remarkably well-preserved specimens have been recovered as the ice has thawed and revealed their resting place, some of which could be 40,000 years old. But while they may look pretty intact, the same cannot be said for their genomes since DNA degrades over time, a process that is accelerated by the presence of microbes and water.

Although scientists have managed to find fragments of mammoth DNA from frozen cells, which raised the possibility they could be stitched back together, they have so far failed to find enough to perform cloning experiments. While some scientists have therefore ruled out using this technique to bring mammoths back from extinction, all hope may not be lost as some think it is possible to merge genes taken from preserved specimens with those of their closest living relative—the Asian elephant.

This is what Church and his team have been endeavoring to do, but there are at least three separate teams trying to recreate the creature, according to The Telegraph. Church began by analyzing the DNA isolated from mammoth specimens and comparing it to that of the Asian elephant, searching for genes that separated them from their relatives. Next, they made exact copies of these stretches of DNA before using a fairly new gene-editing technique to make precise cuts in the elephant genome and insert the desired mammoth genes.

We prioritized genes associated with cold resistance including hairiness, ear size, subcutaneous fat and, especially, hemoglobin [the molecule in red blood cells that transports oxygen around the body]” Church told the Sunday Times. “We now have functioning elephant cells with mammoth DNA in them. We have not published it in a scientific journal because there is more work to do, but we plan to do so.

There are obviously a large number of ethical concerns regarding bringing an extinct animal back to life, but Church argues that reintroducing these animals into ecosystems in Russia could actually have a positive impact on Siberian permafrost, which is gradually receding with climate change. However, not everyone shares his views and others think time and money would be better spent conserving animals that we still have.

[Via The Sunday Times, The Telegraph and RT]

ORIGINAL: IFLScience
by Justine Alford 
March 23, 2015

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