The genome of the extinct thylacine, known as the Tasmanian tiger, has been nearly fully sequenced, according to recent announcements from a de-extinction company. The genome is reported to be over 99.9 percent complete, with only 45 gaps remaining, although no supporting evidence has been provided for this claim.
Experts in the field recognize the complexity of achieving a fully complete genome for any organism. For instance, previous efforts to sequence the human genome faced similar challenges, with only the last segments being completed in recent years.
Thylacines were carnivorous marsupials once widespread across Australia but became confined to Tasmania by the time European settlers arrived. The last known thylacine died in captivity in 1936.
The first sequencing of a preserved thylacine genome occurred in 2017 using tissue from a 108-year-old specimen, which was far from complete. The recent advancements reportedly stem from additional DNA extracted from a 120-year-old tooth.
Although the current thylacine genome is not as comprehensive as the best human genomes, recent technological advancements have facilitated significant progress in sequencing capabilities.
Challenges remain in sequencing ancient genomes due to repetitive sequences that make standard techniques ineffective. Newer methods, capable of sequencing larger DNA segments, can overcome some obstacles, but the fragmentation of old DNA often complicates this process.
Challenging circumstances persist, as most ancient samples yield short DNA fragments. However, the quality of the recent samples has allowed for the recovery of longer sequences, bringing new possibilities to the sequencing efforts.
Due to the absence of other thylacine genomes for comparison, researchers are using related species to assess the comprehensiveness of the current sequencing efforts. However, even if this genome is as complete as claimed, generating living cells containing it presents additional hurdles.
The company aims to genetically modify a living marsupial species, the fat-tailed dunnart, to replicate certain traits of the thylacine. This process does not recreate an exact extinct animal, but instead results in a modified version that resembles the extinct species.
So far, the company has made over 300 genetic edits to dunnart cells, primarily focusing on small changes. Plans are in place to introduce tens of thousands of base pairs of thylacine DNA, though the total number of edits required for success remains uncertain.
When questioned about the lack of evidence supporting its claims, company leadership emphasized a commitment to progress and innovation over traditional scientific publishing, stating their focus remains firmly on de-extinction efforts.
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