How gene editing could revive the extinct Christmas Island mouse

Recently a team of scientists modeled the probability of pulling the species from death, using the Christmas Island rat, a large rodent that became extinct between 1902 and 1908, as their hypothetical subject.

The researchers sequenced the ancient mouse’s DNA and mapped it to some of the animal’s closest living relatives. They were able to recover 95% of the mice’s genome, although they believe the 5% loss greatly complicates any future attempts to revive the species in a process called de-extinction. search was published Today in current biology.

“I am interested in how easy or difficult it is to eliminate extinction by editing. In our article, we have computationally come up with an idea of ​​what we think might be going wrong,” Tom Gilbert, an evolutionary geneticist at the University of Copenhagen and one of the authors of the paper, said in an email. Letter to Gizmodo.

christmas island miceRatus McCleary, also known as the Maclear rat) was one of two species of rat endemic to Christmas Island, a 52-square-mile land area about 200 miles southwest of Indonesia. (other species, bulldog or Rattus nativitatisbecame extinct around the same time.)

Theories abound as to why the rat became extinct; One of the latest Are those black mice (ratos ratos) that were introduced by European settlers contained fleas that in turn carried pathogens, Trypanosoma louissywhich caused the mass extinction of domestic rodents in the early twentieth century.

In the paper, the researchers note the three most well-known approaches to de-extinction: back breeding (selective breeding of ancestral traits in modern animals), cloning, and gene editing. there Many ethical concerns With the return of extinct species, the most important is that money can be spent on preserving the creatures that are still with us.

The team focused on showing how de-extinction works by genetic modification – but they don’t actually intend to bring back any mice. (Gilbert said, “I definitely don’t have a goal to reintroduce the Christmas Mouse. It doesn’t seem like the best use of the money.”)

Researchers sequenced ancient DNA from two samples of Christmas Island mouse skin collected between 1900 and 1902 and currently kept in the Oxford University Museum of Natural History. Comparing the genome of the extinct rat with several modern counterparts – the most important of which is the Norwegian brown rat (norwegian rat), its closest surviving relative – researchers were able to identify traits of extinct mice that they were confident in their ability to replicate.

standing animal will not be genetically identical to the extinct group it represents. But in this case study, gKeratin-containing enes and keratin-binding proteins, which are vital components of hair and bristles, have been well covered across the genomes of mice. So two of the genes involved were in the shape of the rat’s ears on Christmas Island. Taken together, the researchers hypothesized that if they edited the genome of the Norwegian rat, they could replicate the fur color and ear shape of the Christmas Island rat.

TGenes implicated in the Christmas Island rat’s sense of smell, They were different enough that the Norwegian rat’s olfactory genes do not form a good basis for their reconstruction, according to the study. Related genes Nor was the immune response covered by the Norwegian rat. But as the researchers point out in their paper, given the ongoing theory about the extinction of the Christmas Island rat, any resurrected version of the species could theoretically Benefit of using gene immunogens for the Norwegian rat.

this was Guide-From-Presidentfairy The model, which means that the researchers were demonstrating how one can Embark on de-extinction (if they intend) using existing gene editing To bring back related species, such as woolly mammoths or Tasmanian tigers.

“We don’t actually plan to do that, as the world probably doesn’t need more mice, and maybe the money it takes to do the best job possible can be spent on better things, for example, preserving living things,” Gilbert said.

More: Scientists will soon be able to revive woolly mammoths, but should they?