Huge progress made in the race to resurrect extinct species

In a groundbreaking new study, scientists have sequenced RNA from a Tasmanian tiger specimen that is over a century old, bringing the goal of resurrecting extinct species closer to reality.

The specimen, preserved at room temperature in the Swedish Museum of Natural History, has allowed researchers to reconstruct the skin and skeletal muscle transcriptomes from this extinct species, marking a first in the scientific community.

The Tasmanian tiger: A look back

The Tasmanian tiger, or thylacine, stands as a symbol of human-induced extinction. This carnivorous marsupial, once reigning as an apex predator across Australia and the island of Tasmania, faced its downfall post-European colonization.

Deemed an agricultural nuisance, the government set bounties on these creatures in the late 19th century. This resulted in their rapid decline. The last recorded thylacine died in captivity in 1936, but its memory still haunts the conservationist community.

Today, there are renewed efforts to bring the Tasmanian tiger back. Its native Tasmanian habitat remains largely intact, suggesting that its reintroduction could restore past ecosystem balances disrupted by its absence. But reviving the thylacine requires more than just its DNA; scientists must understand its gene expression and regulatory mechanisms, which is where transcriptome (RNA) research comes in.

Monumental achievement

Emilio Mármol, the lead author of the study, highlights the challenges of de-extinction, stating, “Resurrecting the Tasmanian tiger or the woolly mammoth requires a deep knowledge of both the genome and transcriptome regulation.” This sentiment underscores the significance of their research, published in the Genome Research journal, as they’ve provided the first detailed look into the Tasmanian tiger’s RNA.

The team’s ability to sequence the transcriptome from 130-year-old tissue samples, and identify tissue-specific gene expressions akin to extant marsupials and mammals, is a monumental achievement. Moreover, the quality of the recovered transcriptomes allowed for the annotation of previously undiscovered ribosomal RNA and microRNA genes, adhering to MirGeneDB recommendations.

Marc R. Friedländer, an Associate Professor at Stockholm University, commented on the revolutionary nature of the study. He stated that it offers a first look at “thylacine-specific regulatory genes, such as microRNAs, that got extinct more than one century ago.”

Implications for the future

This research doesn’t just hold promise for the Tasmanian tiger. It points to the vast potential locked away in museum specimens worldwide. These treasure troves could hold the keys to understanding, and likely resurrecting, extinct species and even ancient RNA viruses.

Love Dalén, Professor of evolutionary genomics at Stockholm University, foresees a future where scientists could potentially recover RNA from ancient RNA viruses like SARS-CoV2, or even their evolutionary ancestors, from preserved specimens like bat skins.

As we move forward, the interplay of genomics and transcriptomics could usher in a golden age of paleogenetics, going far beyond just DNA. The authors of this study stand at the forefront of this brave new world, anticipating the holistic research developments that await.

More about de-extinction

De-extinction, a fascinating frontier in modern biology, seeks to resurrect extinct species using advanced scientific techniques. But how does this process work, and what are its implications?

The science behind de-extinction

At the heart of de-extinction lies DNA. Scientists extract and sequence DNA from preserved specimens of extinct species, often from museum samples or frozen remains. Once they’ve obtained a clear genetic blueprint, they undertake the process of cloning.

Cloning involves implanting the DNA of the extinct species into the egg of a closely related living species. The living species then acts as a surrogate, carrying the embryo to term and giving birth. If successful, the result is a living, breathing animal of a previously extinct species.

Success stories and challenges

The Pyrenean ibex, extinct since 2000, briefly touched the world of the living in 2003 when scientists successfully cloned a calf. Sadly, the calf lived for only a few minutes due to lung defects, but the experiment proved de-extinction’s potential.

However, challenges abound. Cloning remains an imperfect science, often leading to birth defects. Additionally, even if scientists achieve de-extinction, the reborn species might not exhibit the same behaviors or fulfill the same ecological roles as their predecessors.

Ethical and ecological considerations

De-extinction raises important ethical questions. Is it right to bring back a species that nature, or human interference, has eradicated? And if we do, where will these animals live? Many extinct species lost their habitats long ago, and reintroducing them might disrupt current ecosystems.

Moreover, some argue that funds and energy spent on de-extinction could better serve efforts to prevent currently endangered species from going extinct.

Despite its challenges and controversies, de-extinction captivates the scientific community and the public alike. As laboratory techniques improve, such as extinct RNA extraction discussed in this article, and ethical debates continue, we may yet see lost species roam the Earth once again.

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