“The thylacine samples used for our new reference genome are among the best-preserved ancient specimens my team has worked with. It’s rare to have a sample that allows you to push the envelope in ancient DNA methods to such an extent,” says Beth Shapiro, Colossal’s chief science officer.
Most attempts to reconstruct the genetic code of long-extinct animals face the problem of DNA degradation over time, and we can be talking about hundreds, thousands, and tens of thousands of years. But the 108-year-old specimen, which was stored in alcohol in the Melbourne Museum, allowed the team to isolate the DNA sequence of thylacine, which they claim is 99.9% identical to the original. They were even able to extract more fragile RNA molecules from the sample, allowing the team to see which of the thylacine genes are expressed in certain tissues.
"“With this new resource in hand we will be able to determine what a thylacine could taste, what it could smell, what kind of vision it had and even how its brain functioned,” said Professor Andrew Pask from the University of Melbourne, who is collaborating on the project.
But obtaining the thylacine genes is only one step toward reviving it. Colossal is using gene-editing techniques to alter the genome of tilapin's closest living relative, a hamster-sized marsupial called the fat-tailed dunart, to create a creature as close to tilapin as possible.
The researchers claim to have made more than 300 genetic "edits" derived from thylacine in dunnart cells grown in the laboratory, and have also learned how to induce ovulation in the tiny marsupial and grow its embryos outside the womb - similar to the methods used for humans, i.e. IVF (in vitro fertilization).
But of course, there are those who criticize the plan. Some conservationists argue that the millions of dollars being invested in companies like Colossal Biosciences would be better spent on preserving habitats for animals that are currently endangered, including a fifth of Australia's mammals.
Others argue that it would be unethical to return long-extinct animals to an environment that has been so degraded by human activity that it cannot support the existence of its long-lost inhabitants.
Some scientists believe that this is too technically difficult.
"De-extinction is a fairy tale science," says Professor Jeremy Austin from the Australian Centre for Ancient DNA
However, other scientists argue that research into the return of extinct species can do no harm, even if it only helps to improve understanding of these species and preserve their DNA for future research. The progress made in IVF for the tilapia recovery project "can be applied to the entire marsupial family tree," says Prof. Pask of the Tilapia Integrated Genome Recovery Laboratory.
In addition, there is speculation that they could help ongoing efforts to protect endangered species, such as the Tasmanian devil, which is currently facing the same fate as the Tasmanian marsupial wolf.