The genome of the extinct thylacine, also known as the Tasmanian tiger, has been almost completely sequenced by de-extinction company Colossal. According to the company, the genome is over 99.9% complete, with only 45 gaps remaining to be filled. However, there has been no evidence provided to substantiate this claim.
Emilio Mármol-Sánchez from the University of Copenhagen, Denmark, who was part of the team that extracted RNA from a preserved thylacine, stated that obtaining a fully complete genome of any organism is a challenging task. Thylacines were carnivorous marsupials that once roamed Australia but were confined to Tasmania by the time European explorers arrived. The last known thylacine died in captivity in 1936.
The first sequencing of a preserved thylacine genome was done in 2017 using tissue from a 108-year-old pouch. However, this initial genome was incomplete with many gaps. Colossal claims to have now largely completed this genome with the help of additional DNA from a 120-year-old tooth.
Andrew Pask from the University of Melbourne in Australia, a member of Colossal’s scientific advisory board, mentioned that while their genome is not as complete as the most comprehensive human genome, they utilized similar technologies in the sequencing process. Traditional sequencing techniques are ineffective for plants and animals due to repetitive sequences. The newer long-read techniques can handle larger DNA segments, but old DNA breaks into small pieces, making it challenging to sequence.
Colossal plans to genetically modify a living marsupial, the fat-tailed dunnart, to exhibit traits of the thylacine. The company claims to have made 300 genetic edits to dunnart cells in culture and intends to introduce thousands of base pairs of thylacine DNA in the future. CEO Ben Lamm stated that their focus is on de-extinction rather than publishing scientific papers, hence the lack of evidence supporting their claims.
In conclusion, while Colossal’s efforts to recreate the thylacine are ambitious, the feasibility of generating living cells with this modified genome remains uncertain. The process involves recreating traits rather than resurrecting the extinct animal in its original form. It will be interesting to see how this project progresses in the future.
