Scientists Propose Nine Steps to De-Extinction of Tasmanian Tiger

by johnsmith

The reality of bringing back the thylacine (Thylacinus cynocephalus), also known as the Tasmanian tiger or the marsupial wolf, from extinction using its genome is now a step closer.

The thylacine (Thylacinus cynocephalus). Image credit: University of Melbourne.

The thylacine was a carnivorous marsupial about the size and shape of a medium-to-large size dog.

A fully grown thylacine could measure 180 cm (71 inches) from the tip of the nose to the tip of the tail and stood 58 cm (23 inches) high.

The animal looked like an amalgam of several animals. It had tiger-like stripes running down its lower back and an abdominal pouch, and is one of only a few marsupials to have a pouch in both sexes.

The fossil record shows that the thylacine appeared about 4 million years ago in Australia. By the 20th century it was extinct, or extremely rare, on the mainland but was still found in Tasmania, the island state off Australia’s southern coast.

The species’ demise can be directly attributed to the bounty scheme in place from 1830-1914 that resulted in the killing of several thousand animals and indirectly to the loss of its habitat from farming activity.

The last known thylacine died in 1936, in Beaumaris Zoo in Hobart, Tasmania, and the species was eventually declared extinct in 1982.

“If we look at the modern-day habitat in Tasmania, it has remained relatively unchanged,” said Professor Andrew Pask, a researcher at the University of Melbourne.

“This means it provides the perfect environment to re-introduce the thylacine, enabling it to reoccupy its niche. But bringing back an animal costs a lot of money.”

Thanks to a recent $5 million philanthropic gift, Professor Pask and his colleagues at the University of Melbourne are establishing a world-class research lab for de-extinction and marsupial conservation science

“The gift will be used to establish the Thylacine Integrated Genetic Restoration Research (TIGRR) lab, which will develop technologies that could achieve de-extinction of the thylacine and provide crucial tools for threatened species conservation,” Professor Pask said.

“Thanks to this generous funding we’re at a turning point where we can develop the technologies to potentially bring back a species from extinction and help safeguard other marsupials on the brink of disappearing.”

The donation came from the Wilson Family Trust.

“The story of the thylacine and its unceremonious exit from this world really touched our family,” said Mr. Russell Wilson.

“We came across Professor Pask’s incredible work, believe it or not, via some YouTube clips on him talking about his research and passion for the thylacine and Australian marsupials.”

“We realize that we are on the verge of a great breakthrough in science through improvements in technology and its application to the genome. The benefits of this open research will be wide and varied.”

Professor Pask and co-authors propose nine key steps to de-extinction of the thylacine.

“Step 1: the good news is that this step is complete; we’ve released the thylacine genome which is basically a complete genetic blueprint or set of instructions on how to build a thylacine; this is an essential first step in any de-extinction project, and the likelihood of de-extincting the animal is completely reliant on the quality and accuracy of that genome.

Step 2: this is another one the team have already completed; we now have the sequence for several species which represent the thylacine’s closest relatives, which includes the dunnart or marsupial mouse; the species with the most similar DNA will provide the living cells and template genome that can then be edited to transform it into a thylacine genome.

Step 3: this is a large bioinformatics (or computational) project that compares marsupial genomes to identify all the differences that would potentially need to be edited into the hosts genome to create a ‘thylacine’ cell; this element is currently a major objective of the new TIGRR lab.

Step 4: this step is now in development with the TIGRR lab and the Australian Research Council; we have derived stem cells for our model marsupial species, the fat-tailed dunnart, from which a lot of the techniques needed for our thylacine de-extinction will be developed; as part of TIGRR lab, we will establish methods that work in all marsupials; with this tool, we can effectively bio-bank diversity in ‘at-risk’ marsupial populations and protect against the loss of species that are threatened or endangered.

Steps 5 to 7: these steps require the development of assisted reproductive technologies (ART) for marsupials and is in development with the TIGRR lab; these techniques are required to use living stem cells to make an embryo and then successfully transfer it into a host species’ uterus.

Steps 8 to 9: this is where de-extinction efforts for marsupials have a distinct advantage over other mammals; all marsupials give birth to tiny young which complete development in the pouch while suckling milk; instead, as part of the de-extincting process, this can be replaced from a very young age with bottle feeding; it means that unlike other animals that require long and complicated gestation times, we can generate living animals in a range of host species and potentially without the need for a host at all.”

According to the team, these nine steps are likely to take a decade or more, but the work along the way will be of immediate conservation benefit for marsupials, as well as developing the technology necessary to bring back the iconic Australian animal.

“The tools and methods that will be developed in the TIGRR Hub will have immediate conservation benefits for marsupials and provide a means to protect diversity and protect against the loss of species that are threatened or endangered,” Professor Pask said.

“While our ultimate goal is to bring back the thylacine, we will immediately apply our advances to conservation science, particularly our work with stem cells, gene editing and surrogacy, to assist with breeding programs to prevent other marsupials from suffering the same fate as the Tassie tiger.”

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