Functioning gene of extinct animal gives hope for studying long-lost species.
The extinct Tasmanian tiger (Thylacinus cynocephalus) has been resurrected — or at least part of its DNA has — in a mouse.
Typically of Australia's weird and wonderful animals, the Tasmanian tiger, also called the thylacine, wasn't actually a tiger. It looked like a dog, but was in fact a marsupial, complete with a pouch for rearing its young. The last known Tasmanian tiger died in Hobart Zoo, Tasmania, in 1936, after the species was hunted out of existence in the wild.
By resurrecting part of its genetic sequence in a mouse, researchers have found a way to study how the species evolved, in the hope of learning its place in the tree of life. The technique could also be applied to other extinct animals.
From sequence to function
Some preserved remains of the Tasmanian tiger exist, including those of the young from the pouch of an adult, collected 100 years ago and kept in ethanol in the Museum Victoria in Melbourne. Andrew Pask at the University of Melbourne and colleagues at the University of Texas in Houston took samples from this specimen, and from some 100-year-old Tasmanian tiger skin held in the same museum, and extracted DNA from them.
Pask and his colleagues used a portion of a gene called Col2a1, which regulates the development of cartilage and bone. They injected it into a mouse embryo in place of the mouse’s corresponding section of Col2a1. The mouse embryos grew, complete with their exchanged genetic information, and proceeded to develop cartilage and bone as normal. The results are reported in the journal PLoS ONE.1
This is the first time DNA from an extinct animal has been shown to perform its intended function in a living animal. “Until now we have only been able to examine gene sequences from extinct animals,” says Pask. “This research was developed to go one step further to examine extinct gene function in a whole organism.”
"I think that it is important that one takes the step into an organism to try understand how ancestral or extinct genes and genetic elements worked," comments Svante Pääbo, director of the Max-Planck-Institute of evolutionary Anthropology, Leipzig, Germany.
But before fans of Jurassic Park get too excited, this gene resurrection doesn’t mean that we will be able to recreate a Tasmanian tiger any time soon. The exact pathway for this gene’s activity could be very different for the two animals, the researchers say, and the precise function of the gene in the Tasmanian tiger is impossible to work out without looking at every step in the pathway.
So the authors urge caution in interpreting the results, but say their method could ultimately allow access to genetic information thought to be forever lost when the last of a species drew its final breath.
Pask, A. J., Behringer, R. R. & Renfree, M. B. PLoS ONE 3, e2240 (2008)