A group of scientists in Dallas is trying to bring back the woolly mammoth; their first step is woolly mice.
Early this month researchers at Colossal Biosciences, a de-extinction company in Texas, unveiled several adult mice with thick, golden fur. The mice had been genetically modified as zygotes before being transferred to an adult mouse to carry them to term.
Gene edits were made using a variety of methods, including those in the CRISPR/Cas9 system, and built upon previous understandings of which genes are responsible for hair development and structure. This enabled researchers to target texture, shape and length, in addition to altering the orientation of hair follicles on the body.
One of the gene alterations included the deactivation of Tgfa, a growth factor regulating hair development that is already deactivated in woolly mammoths.
The gene edits went beyond the visual, as several mice had their fat metabolism altered to closer resemble that of the mammoth’s, which is expected to contribute to improved cold adaptation.
Ultimately, of the 10 genes targeted, seven were successfully altered at once, through up to eight different modifications. Of those, three were deliberately informed by comparative mammoth genomics. It is worth noting that while the most discussed results focus on a few golden, fluffy mice, images included in the released preprint include a variety of mice with varying fur colors and textures.
The results prove a successful attempt at mutating multiple genes simultaneously, which can prove a particularly difficult task as the number of alterations increases. Often, multiple gene knockouts can be tricky, with not all intended modifications accomplished.
It is through this multiple alteration method that Colossal Biosciences intends to recreate the mammoth using the closely related template of the Asian Elephant. However
This announcement reignites a debate that has been brewing for over a decade: should we be making an effort to bring back certain extinct species, and if so, is the woolly mammoth worth it?
While the movement for de-extinction has a plethora of excited supporters, for mammoths or otherwise, it has been criticized for pulling attention and financial resources away from the mission of preventing new extinctions from taking place. Biologist Paul Ralph Ehrlich wrote for Yale in 2014, “Spending millions trying to de-extinct a few species will not compensate for the thousands of species lost to human activity.”
Additionally, there is a concern for modifying mammals that thrived in a long-gone environment, not taking into consideration the impact of climate change. Ehrlich cites a biologist colleague stating “…there are far more urgent and tractable ways for creating imagined futures that don’t include bringing back a “pet” for humanity before you’ve had time to prepare its terrarium.”
Research has also suggested that certain mammoth populations had amassed a plethora of damaging genetic mutations that had made their existence very difficult towards the end of their run. With this in mind, scientists have been setting clear goals for how they expect to return the mammoth, or a resembling mammal, to the modern era.
Ben Lamm, Colossal’s co-founder tells nature “It’s really about rebuilding extinct species for today and looking for lost biodiversity and lost genes that drive those phenotypes.”
As of now, Colossal intends to examine the temperature preferences and diet impact of their newly edited mice, which will provide further insight into the effectiveness of these phenotypic alterations.
