# Stem Cell Editing, Comprehensive Genome Sequencing, and Cane Toad Mitigation: Groundbreaking Developments in De-Extinction and Conservation
In recent years, the idea of de-extinction—reviving species that have been absent from the planet for a long time—has intrigued both scientists and the general public. A key player in this arena is **Colossal**, a biotechnology company initially established to bring back the woolly mammoth. However, Colossal has broadened its focus to incorporate other extinct species such as the **dodo** and the **thylacine** (commonly referred to as the Tasmanian tiger). The company has made remarkable progress in stem cell editing, genome sequencing, and conservation initiatives aimed at safeguarding endangered species from extinction.
## The Thylacine: A Target for De-Extinction
The **thylacine**, a carnivorous marsupial endemic to Tasmania, became extinct in 1936 when the last known individual passed away in captivity. Although the biology of the thylacine is quite different from that of the woolly mammoth, Colossal’s advancements on this species have gained momentum thanks to the relatively short generation time of marsupials and their distinctive reproductive characteristics.
Marsupials, in contrast to placental mammals, give birth to underdeveloped offspring that continue to develop in the mother’s pouch. This unique aspect of their biology offers both challenges and opportunities for de-extinction endeavors. While the technology for altering marsupial reproduction is not as advanced as that available for placental mammals, recent progress in stem cell editing and genome sequencing is quickly bridging that gap.
## Cane Toad Mitigation: A Conservation Initiative
Alongside its de-extinction endeavors, Colossal has ventured into **conservation biology** with efforts to safeguard currently living species from extinction. A significant threat to Australian marsupials is the **cane toad**, an invasive species known for secreting **bufotoxins**, a category of toxic substances that can be deadly to native predators.
The bufotoxins attach to a protein known as **ATP1A1**, which manages ion transport across cell membranes. In the cane toad’s home range in Africa, various species have developed mutations in the ATP1A1 gene that diminish bufotoxin binding, rendering them immune to the toxin. Colossal’s research team, led by **Andrew Pask**, has successfully incorporated this mutation into a marsupial stem cell line’s genome, enhancing resistance to bufotoxins more than 6,000 times.
This advancement holds significant promise for **quolls**, a carnivorous marsupial species that faces endangerment due to cane toad consumption. Colossal’s team has produced quoll stem cell lines and is striving to introduce the cane toad resistance gene into the natural population. If achieved, this could avert the quoll from becoming another candidate for de-extinction.
## Genome Editing: Important Breakthroughs
One of the most pivotal components of de-extinction is **genome editing**. For the thylacine project, Colossal has performed over 300 distinct modifications to the genome of the **fat-tailed dunnart**, the thylacine’s closest living relative. These modifications aim to closely align the dunnart’s genome with that of the thylacine.
Additionally, the company has procured an almost complete genome sequence from a thylacine specimen preserved in ethanol for over a hundred years. This specimen contains both short DNA fragments and longer sequences exceeding 10,000 base pairs, facilitating a more thorough genome reconstruction. Presently, only 45 gaps remain in the thylacine genome, and the team anticipates resolving these shortly.
Such a level of genomic completeness is exceptional for an extinct species and instills a high degree of confidence that the team has uncovered all the significant genetic disparities between the thylacine and its closest living relatives.
## Messenger RNA: An Uncommon Discovery
In an extraordinary stroke of fortune, the thylacine specimen also yielded **messenger RNA (mRNA)** molecules, which are the products of active genes. This enables researchers to investigate which genes were functioning in specific tissues of the adult thylacine. For instance, mRNA analysis could shed light on the animal’s olfactory, gustatory, and visual capabilities, along with brain function.
This is a notable advancement since mRNA is generally quite delicate and seldom preserved in extinct species. By analyzing these molecules, scientists can acquire a deeper understanding of the thylacine’s biology, which could prove essential for accurately recreating the species.
## Thylacine Wolf Accelerated Regions (TWARs)
One particularly fascinating element of Colossal’s research is the identification of **Thylacine Wolf Accelerated Regions (TWARs)**—DNA segments that appear to have undergone rapid evolution in both thylacines and wolves. Despite being
