Revived Genome of Extinct Frog Will Be Used in Cloning Experiments

This frozen extinct frog cloning experiment has about all the ingredients you could wish for a certain kind of movie -- except its just about a harmless frog. On the other hand, the techniques used to revive this extinct species are being developed to be applied on all kinds of reptiles. Towards this goal, Australian scientists sucessfully reconstructed the complete genome of an extinct frog species that gave birth through its mouth by first reviving cells that were frozen for decades, and then fusing them together with an egg from another species of frog. By using their cloning technology to combine the unfrozen dead nucleus and the fresh egg, the species of Rheobatrachus silus (gastric-brooding frog) could be on its way to live once again.

The ancient frog gave birth through its mouth by first swallowing its fertilized eggs, keeping them in its stomach until they were ready to hatch and then releasing the young ones via the mouth.

The revival of the genome was part of the Lazarus Project that is working on a so called de-extinction program to bring the dead species of frog back to life.

So far the team of scientists was able to reactivate dead cells into living ones by unfreezing and implanting the nuclei, taken from fossilized tissues of the frog that were collected in the 1970s and preserved in a deep-freezer.

The technique used is known as somatic cell nuclear transfer, which is often used and also works for humans. The researchers first collected fresh eggs from a related species of frogs called Great Barred Frog, Mixophyes fasciolatus and then replaced the egg nuclei with the dead nuclei obtained from the gastric breeding frog. The cells began to grow like an embryo, although not many eggs lived for more than a few days.

Genetic tests of the embryos confirmed that they had the genetic material of the extinct frog.

"We are watching Lazarus arise from the dead, step by exciting step. We've reactivated dead cells into living ones and revived the extinct frog's genome in the process. Now we have fresh cryo-preserved cells of the extinct frog to use in future cloning experiments," said professor Mike Archer, of the University of New South Wales, in Sydney, the leader of the Lazarus Project team, according to a news release.

Archer said that their experiment of completing the genome of an extinct frog species demonstrates a conservation tool that holds great promise for many amphibians of the world that are threatened, or already doomed, by extinction. The species worked on in the present study - R. Silus - has vanished in 1979.

Researchers from around the world were discussing the future of extinct species that could possibly be brought back to life at the "TEDx DeExtinction" event in Washington DC, hosted by Revive and Restore and the National Geographic Society, were the Lazarus project was also a topic, the news release said.