A team of scientists, led by the University of New South Wales (UNSW), has used sophisticated cloning techniques to revive and reactivate the genome of an extinct Australian frog by implanting a “dead” cell nucleus into a fresh egg from another frog species.
Rheobatrachus silus was a bizarre gastric-brooding frog that swallowed its eggs, brooded its young in its stomach and gave birth through its mouth. The frog species became extinct in 1983.
The Lazarus Project team, however, has been able to recover cell nuclei from tissues harvested in the 1970s and kept in a conventional deep freezer since then. The results of this study have not yet been published, however UNSW Professor Mike Archer spoke about the Lazarus Project this week at the TEDx DeStinction event, as well as his desire to clone the extinct Australian thylacine – the Tasmanian Tiger. The Washington DC event was hosted by Revive and Restore and the National Geographic Society to allow researchers from around the world to discuss progress and plans to “de-extinct” other extinct species, such as the woolly mammoth, dodo, Cuban red macaw and New Zealand’s giant moa. The scientists involved also discussed some of the ethical issues surrounding such de-extinctions. Can such species be reintroduced into the wild responsibly? Should they be reintroduced or even brought back at all? The event was livestreamed to the public.
Over the last five years, the Lazarus Project research team has performed repeated experiments using a laboratory technique known as somatic cell nuclear transfer. Fresh donor eggs were harvested from the distantly related Great Barred Frog, Mixophyes fasciolatus. The egg nuclei were inactivated and replaced with dead nuclei from the extinct frog. Spontaneously, some of the eggs began to divide and grow into early embryonic stages – tiny balls of many living cells. None of the embryos survived beyond a few days; however, genetic testing revealed the dividing eggs contain the genetic material from the extinct R. silus frog.
“We are watching Lazarus arise from the dead, step by exciting step,” says Archer, the leader of the Lazarus Project team. “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.
“We’re increasingly confident that the hurdles ahead are technological and not biological and that we will succeed. Importantly, we’ve demonstrated already the great promise this technology has as a conservation tool when hundreds of the world’s amphibian species are in catastrophic decline.”
Dr. Andrew French and Dr. Jitong Guo, formerly of Monash University, performed the technical work in a University of Newcastle laboratory. They were led by frog expert Professor Michael Mahony and were joined by Mr. Simon Clulow and Dr. John Clulow. Professor Mike Tyler, University of Adelaide, preserved and provided the frozen specimens. Tyler extensively studied both species of gastric-brooding frog – R. silus and R. vitellinus – before they vanished in the wild in 1979 and 1985 respectively.