Breakthroughs sometimes pop up in unexpected places. The researchers working on the international effort to bring back the thylacine say they found theirs in a long-ignored bucket in the back of a cupboard at a Melbourne museum.
It contained a surprisingly well-preserved head of the extinct marsupial, also known as the Tasmanian tiger.
“It was literally a head in a bucket of ethanol in the back of a cupboard that had just been dumped there with all the skin removed, and that had been sitting there for about 110 years,” Prof Andrew Pask, the head of thylacine integrated genetics . recovery research (with the acronym Tigrr) laboratory at the University of Melbourne, says.
“It was quite dirty, a completely gruesome sight. People cut off large pieces of it.”
Aesthetics aside, the specimen had a lot going for it. It contained material that scientists thought would be impossible to find, including long RNA molecules essential to reconstructing an extinct animal’s genome. “That was the miracle that happened to this monster,” says Pask. “It blew my mind.”
A year later, he says the work of the team of Australian and American scientists trying to resurrect the species has progressed more than expected at this stage. “We’re further than I thought we would be, and we’ve completed a lot of things that we thought would be very challenging and others said would be impossible,” he says.
The plan to ‘extinct’ the thylacine
The project to bring back the thylacine is run by Colossal, a Texas-based biotech “extinction and species preservation” company that also aims to recreate the woolly mammoth and the dodo use of genetic engineering techniques.
Led by technology and software entrepreneur Ben Lamm, Colossal has raised US$235m, directly employs 155 people and funds research at 13 labs around the world. This includes the Tigrr laboratory, which operates at the University of Melbourne’s School of Biosciences.
The thylacine was Australia’s only marsupial top predator. It once lived all over the continent, but was restricted to Tasmania about 3,000 years ago. Dog-like in appearance and with stripes across its back, it was extensively hunted after European colonization. The last known survivor died in captivity in 1936 and it was officially declared extinct in the 1980s.
Colossal says researchers have made several breakthroughs in its work on the species, putting the company much closer to its goal of returning it to the wild. They include what they say is the highest quality ancient genome ever produced, with just 45 gaps in a genetic blueprint containing about 3 billion pieces of information.
Lamm says this is an “incredible scientific leap” that puts the program “on track to eradicate the thylacine,” while other recent breakthroughs will be helpful in protecting critically endangered species. “We are pressing as fast as possible to create the science needed to make extinction a thing of the past,” he says.
The soft tissue of the Museums Victoria specimen, which researchers have dubbed “head in a bucket”, contains preserved long stretches of DNA – genetic material that is the same in almost every cell nucleus in a body – but also long RNA molecules. Pask says the latter was decisive, and unexpected.
RNA is much less stable than DNA. It varies in different types of tissue and contains what is effectively a readout of the active genes required for a particular tissue to function. This meant that researchers were able to obtain information related to the animal’s nose, eyes, tongue and other facial material, giving a picture of what a thylacine could taste and smell, what kind of vision it had and how its brain functioned .
Pask says the result is the first annotated extinct animal genome. “It helps us prove that what we’re bringing back is really a thylacine and not a hybrid animal,” he says.
The thylacine researchers aim to take stem cells from a living species with similar DNA to a thylacine, the smaller fat tail thin artand turn them into the closest approximation of thylacine cells possible using gene-editing expertise developed by George Church, a professor of genetics at Harvard Medical School and Colossal’s co-founder.
A thing that looks like a thylacine – but what comes next?
The announcement about the genetic breakthrough came ahead of an event at the SXSW festival in Sydney on Friday, where Lamm and Pask will talk about their work with actor Luke Hemsworth. The Hemsworths were vocal and financial supporters of the project.
Colossal says it has also developed the first artificial reproductive technology to induce ovulation in marsupials, a step that could lead to captive breeding programs for endangered species, and single-cell embryos fertilized and grown to more than halfway through pregnancy in an artificial womb.
As for when a thylacine might be created, Pask says he expects the first “thylacine-looking thing” to be born within three to five years, but that he “wouldn’t call it a thylacine”. He says the researchers are confident of creating a thylacine’s skull, bones and even stripes, but there are “still other things we don’t know how to do yet”.
Other scientists are watching with varying degrees of caution and skepticism. Some ask why so much funding and effort is being put into bringing back species when thousands that are still alive are on the brink of extinction. Euan Ritchie, a professor of wildlife ecology and conservation at Deakin University, says it’s an ambitious project and is likely to lead to breakthroughs that could help conservation. But he says there will be other challenges “if-and-when we bring back thylacine-like animals”.
“I think we’ll probably get some thylacine-like animal, but they won’t actually be thylacines. The question is: what comes next?” he says.
“How will they behave in nature and what effects can this have in the ecosystems? We have no idea how they are going to behave because there are no living thylacines left, and when you can bring back a thylacine-like animal, it has no other thylacine-like animals to learn from.
“It is at least as big a challenge, if not a bigger challenge, than the genetic challenge. As an ecologist, this is the great unknown.”
