Alive and Hopping31 May 2013
When Michael Crichton wrote Jurassic Park way back in 1990, the idea that extinct animals could be brought back through cloning technology wasn’t pure fantasy, though it was certainly at the fringes of what was conceivable at the time.
But time passes, and science marches ever on.
On March 15th, the National Geographic Society and the Long Now Foundation (an American charity that promotes very long-term planning) hosted a one-day ‘symposium’ in Washington, D.C., called ‘TEDxDeExtinction’. Modelled after the TED conferences (of the renowned TEDTalks), it heralded the advent of a new field of, and a new purpose for, biological science: de-extinction. In other words, real-life Jurassic Park shit, except without the dinosaurs; their remains are far too old to retrieve decent DNA from, and we have no reliable way to fill in the considerable genomic gaps.
While we are still very much on the frontier of de-extinction, the basic technique (called somatic nuclear cell transfer, or SNCT if you’re super cool) is more or less the same as what Crichton described in that classic tale of dinosaurs gone wrong. DNA is extracted from a preserved specimen of the extinct species, let’s say, a mammoth. Then an oocyte (egg cell) is extracted from an individual of a closely-related surviving species, which in the mammoth’s case would be an Asian elephant. The DNA in the oocyte is deactivated (often by exposure to UV light) and the DNA from the extinct animal is inserted into the oocyte. The oocyte is then inserted into a surrogate mother of the extant species; again, for a mammoth, we would find a nice, maternal lady elephant. If all goes well, gestation occurs as normal and the mother gives birth to a clone of an animal that may have been dead for thousands of years.
The problem is, all rarely goes well. However, hope for de-extinction is not lost. Professor Michael Archer was one of the speakers at TEDxDeExtinction and the sole Australian among them. As Director of the Australian Museum, he instigated an attempt to resurrect the insanely awesome thylacine (or ‘Tasmanian tiger’ for you plebs). He is now leading the Lazarus Project at the University of New South Wales, which is an attempt to bring the gastric-brooding frog back from the dead, just like the project’s Biblical namesake.
The southern gastric-brooding frogs were, in layman’s terms, pretty fucking cool. When the gastric-brooding frog’s eggs were fertilised (which occurred outside the body because gastric-brooding frogs didn’t do icky sex stuff), the mother would swallow them. Luckily for everyone involved, a chemical called prostaglandin E₂ (PGE2) found in the coating of the eggs switched off the cells in the lining of the stomach which produce hydrochloric acid. This effectively rendered the mother’s stomach a quasi-uterus. The eggs would hatch; tadpoles would grow and develop into froglets within their mother. By this point the stomach became so bloated that the mother’s lungs would collapse and she would breathe through her skin-until she vomited her children up through her mouth.
Mike Tyler is an associate professor at the University of Adelaide, an Ig Nobel Prize winner, and a living legend on the Australian amphibian scene. Tyler was among the first human beings to ever witness a gastric-brooding birth in 1974, and the first to discover and describe the precise mechanisms of this utterly unique method of parental care. He also provided the specimens currently being used by the Lazarus Project and, although he is not directly involved, says he comes up with ideas from time to time when the team at UNSW are stuck. When Farrago asked him about the moment when he first saw a froglet emerge from its mother’s gaping mouth, he describes it simply as “staggering”. He used a mechanised camera, capable of taking ten shots in two seconds, to record the occasion and when his peers saw the remarkable images he recorded, he was accused of trick photography. “People didn’t want to believe it”, Tyler says.
The reasons for the species’ extinction remain inscrutable. Some claim the frogs were an early victim of Chyridiomycota–a fungus which has been decimating frog populations worldwide since at least the early 90s. However, Tyler tells Farrago that he examined gastric brooding frog specimens and could not find any sign of the spores characteristic of a chytrid death. A popular explanation is habitat loss, but Tyler also attests that he knew of a wild population that thrived amongst concrete slabs laid down for the construction of a bridge: “Not what you’d call pristine environment”, he says.
Given the extinction of the gastric-brooding frogs remains such a mystery, how do we know if they’ll be able to be ‘re-wilded’, that is, re-established in their natural habitat? Some would consider it unethical to bring a whole species of animal into the world just so it may exist in laboratories and zoos. This is a particularly serious issue with resurrecting long-gone animals–the kind that have not been gone for decades or centuries but millennia. Even if we are able to create a living, breathing mammoth, how could we recreate the physical environment in which they lived? The fact that Earth’s climate has changed considerably in the last few thousand years (and continues to change, now more rapidly than ever) is just one of many sticking points. Furthermore, we don’t know if a species could survive in the wild without many other species of plants, animals, fungi and bacteria with which it once co-existed.
While Tyler says that seeing the gastric-brooding frogs brought back would be exciting and would open the door for all sorts of projects and experiments–in de-extinction and other fields–he believes that completing the catalogue of existent species is vital. “There are four undescribed species sitting in my laboratory”, he tells Farrago matter-of-factly.
So far, the Lazarus Project has produced promising yet limited results. They can make an oocyte with gastric-brooding frog DNA just fine, and a number of these have spontaneously divided. As with any fertilised oocyte, they divide again and again and again, each cell with gastric-brooding DNA, forming a blastula–comprised of about one thousand cells–after three days. So far, none of the Lazarus Project’s embryos have gotten past this stage. A blastula is not a frog, nor a froglet, nor even a tadpole. But it is certainly a start.