Frankenstein's Cat: Cuddling Up to Biotech's Brave New Beasts (12 page)

By stockpiling DNA from exotic animals, we can also prevent other species from developing such crippling diversity problems in the first place. At ACRES, these DNA samples are kept behind the door labeled “Cryobiology Room,” and Dresser takes me inside. The room is cold, dark, and unimpressive. There is no obvious high-tech lab equipment, just a cluster of metal tanks, the approximate size and shape of kegs, lined up along the wall. But appearances can be deceiving. “That is years of science in there,” Dresser says, gesturing at the tanks.

This is the Frozen Zoo, where an entire wild kingdom is packed into a few square feet. Dresser opens one of the tanks, which are kept at a frigid −373 degrees Fahrenheit, and nitrogen vapor comes swirling out. Suspended in the fog is a metal rack packed with tiny yellow straws. Each straw contains a cell sample from a different animal. They hold skin cells, sperm, eggs, and whole embryos from thousands of different individuals, including gorillas, elephants, rhinos, monkeys, buffalo, frogs, storks, cranes, lions, tigers, and bears. If Dresser is a modern-day Noah, these tanks are her ark. (Indeed, the story of Noah pops up again and again in the world of endangered-species cloning, from the little cloned gaur that was named after the biblical figure to the researchers who invoke the tale when discussing their DNA banking projects.) When the samples are frozen just so—pumped full of a cryoprotectant that prevents cells from bursting as the temperature drops—they can survive indefinitely.

Frozen zoos provide us with the opportunity to preserve the genetic diversity of a species
before
catastrophe strikes. If they had existed when the cheetah population was at its most robust, scientists could have packed the tanks with hundreds or thousands of cheetah skin samples. If we had these cells available today, we could look through them for genetic variants that have disappeared from the wild. We could clone these animals back into existence, and set them free on the African savanna, restoring genetic lineages that had died out.

According to Duane Kraemer—who established his own project to bank wildlife DNA after his students showed an interest in species conservation—what we really need to do is store cells from animals that are
not
endangered, preserving their diverse DNA for the future. “We should be systematically sampling populations and putting their cells into storage,” he says. “Our species has a tendency to wait until we’re in trouble until we look for solutions.”

We can change that with frozen zoos, which are popping up all over the planet. The San Diego Zoo has a particularly well known one, and eighteen institutions in eight countries are participating in the Frozen Ark Project, run out of Britain’s University of Nottingham. Together, these institutions have collected and preserved 48,000 DNA samples from more than 5,500 species; the collective goal is to hit 10,000 species by 2015. If we store these samples properly, we’ll be able to use them to pull off remarkable scientific feats, including resurrecting species that die out in the wild. For example, the San Diego Zoo’s ice-cold collection includes cells from the po’ouli, a small Hawaiian songbird believed to be extinct. (The last known po’ouli died in 2004.) Scientists haven’t yet figured out how to clone birds, but if they do, the po’ouli DNA is sitting there in liquid nitrogen, ready to be brought back to life—and to give the fabled phoenix a run for its money. (Who needs a mythological bird that rises from the ashes when we’ve got a real one?)

The closest that scientists have gotten to species resurrection is the cloning of the Pyrenean ibex, a Spanish mountain goat. By 1999, there was only one Pyrenean ibex left in the world. Her name was Celia, and the rest of her kind had been hunted to extinction. One day in January 2000, Celia found herself under the wrong tree in Spain’s Ordesa National Park. The tree toppled, crushing Celia and officially snuffing out the Pyrenean ibex for good—or so it seemed.

The year before Celia’s death, some forward-thinking researchers had swiped a sample of her skin and stored the cells in liquid nitrogen. Then, after the elderly goat was gone, the scientists thawed out her cells and used nuclear transfer to get the ibex DNA into a whole clutch of domestic goat eggs. For their surrogate mothers, the researchers used hybrids—female crosses between the domestic goat and the Spanish ibex, a subspecies closely related to the Pyrenean variety. After the five-and-a-half-month gestation period, one hybrid was still pregnant. Researchers opened her up and delivered Celia’s clone. The newborn kid opened her eyes and moved her legs, but she struggled mightily for air, and died just a few minutes after her birth. A necropsy revealed lung abnormalities, a defect that’s been observed in other young clones. It was the briefest of resurrections, but the return of the Pyrenean ibex gave scientists hope that cloning could indeed bring back other extinct species.
*

Several labs have embarked upon projects to clone species that died out long before Celia. Australian researchers want to revive the thylacine, one of the many strange creatures that evolved in the land down under. Like a kangaroo, the thylacine was a marsupial that carried its young in its pouch, but it looked more like a hyena, and the dark brown stripes running down its back earned the animal one of its other names: the Tasmanian tiger. (It’s also sometimes called the Tasmanian wolf.) The mammal has been extinct since 1936, when the last thylacine died at the Hobart Zoo. The technology used to painstakingly preserve cells in frozen zoos was not around when the thylacine disappeared, but we’ve held on to a few strange souvenirs: dried thylacine skins and wrinkled, hairless thylacine pups floating in alcohol-filled jars.

Clearly, these are not ideal conditions for DNA, which degrades over time, but a few Australian scientists think that they can use these samples to clone the Tasmanian tiger. They haven’t done so yet, but other researchers have managed to get some decent DNA from these thylacine samples. In 2008, one team of scientists isolated a piece of DNA from a baby thylacine that had been stored in alcohol a hundred years ago. Then they put the thylacine fragment, which controlled bone and cartilage formation in the animal, into the genomes of mice. The DNA jumped right back into action, performing its normal regulatory duties in the bodies of these transgenic mice. Triumphant, the scientists wrote: “[W]e have restored to life the genetic potential of a fragment of this extinct mammalian genome.” The following year, a different group of researchers got their hands on some thylacine hair and published the complete sequence of two Tasmanian tigers’ mitochondrial genomes. These were exciting developments for those who dream of seeing packs of striped marsupials hunting down wombats and wallabies. But let’s not count our Tasmanian tigers before they hatch; the deterioration of the DNA in our thylacine samples means that bringing the animal back to life is still a long shot.

The longer a species has been extinct, the more difficult the resurrection. That makes the oft-cited goal of cloning a woolly mammoth—last seen alive circa ten thousand years ago—an especially daunting one. In recent years, several mummified specimens have been discovered under the Siberian permafrost. The ice has helped preserve the carcasses and, scientists hope, the DNA they contain. Russian, Japanese, and Korean researchers—including the (in)famous cloner Hwang Woo Suk—have joined forces to extract DNA from these carcasses and re-create the prehistoric giants using elephants as egg donors and surrogates. (During his 2006 trial for fraud, embezzlement, and other alleged offenses, Woo Suk admitted that he’d spent some of his research funding trying to buy mammoth tissue from the Russian mafia.)

The scientists have a … well … mammoth task ahead of them. To use nuclear transfer, they’ll have to find a cell in pristine condition. That will be a difficult task; the passage of thousands of years, cycles of freezing and thawing, and the presence of various microbes can all damage genetic material, and the DNA in even the best mammoth specimens unearthed so far has shown evidence of degradation. The other option—to sequence enough different genetic fragments to yield a complete, error-free genome and then build a set of chromosomes from scratch—is even more daunting. Add to that all the normal challenges that accompany cloning, plus the difficulties of working with the elephant reproductive system. (Among other obstacles, researchers will need to navigate more than
eight feet
of reproductive tract to get a cloned embryo inside an elephant’s uterus.)

If that doesn’t sound tough enough, we could try going back even further, to the Jurassic era. Dinosaur DNA is way too far gone for cloning, but the famed paleontologist Jack Horner has a different proposal for bringing back the reptilian beasts. Birds, scientists now know, are the modern descendants of dinosaurs. In fact, the genomes of birds and dinosaurs are so similar that Horner thinks we can reverse-engineer the reptilian beasts from chicken embryos. To make a “chickenosaur” that looks like a prehistoric raptor, we wouldn’t even have to add new genes to a chick embryo—we’d just have to alter how its current genes were expressed, Horner says. Put a bird cell in a dish and bathe it in just the right growth factors, and we might be able to run evolution in
reverse
, prodding chicken DNA to build something that looks like it belongs in
Jurassic Park
.

Unfortunately, even if we can surmount all the technical issues, bringing extinct animals back might prove to be more cruel than kind. What would become of a resurrected mammoth or a Tasmanian tiger—or even two or three? They would be mere curiosities, carnival creatures confined to labs and zoos. Life in the wild likely wouldn’t be much better. Though Zimov has kindly offered up Pleistocene Park as a potential refuge for any future mammoth clones, we’d be sending the animals out into a world vastly different from the one they once knew. We might be setting the animals up for a miserable existence on a planet that can no longer give them what they need.

Cloning concerns environmentalists for just this reason—because the technology allows us to just churn out new animals without restoring or repairing their habitats. To many biologists, cloning is all sizzle and no substance, a high-tech spectacle that fails to address habitat loss, poaching, pollution, and the other human activities that put wildlife at risk in the first place. David Ehrenfeld, a biologist at Rutgers, raised this concern in an article in
Conservation Biology.
Cloning, he wrote, “is a glamorous technology, and there is the danger of creating the false impression in the mind of a technology-infatuated public that it offers an easy, high-tech solution to the problem of extinction. Not only can this divert resources from conservation methods that have a much better chance of success, but repeated cloning failures may disillusion the lay supporters of conservation.” Cloning, he concluded, “should never be a conservation strategy of first resort.”

But the time for first resorts has come and gone, and safeguarding species is an all-hands-on-deck enterprise. Indeed, for cloning to have a real shot, laboratory scientists must work with conservationists; researchers can make all the fauna facsimiles they want, but the lab babies will need somewhere to live. The prospect of unleashing a thousand clones in the planet’s forests and prairies may be pure fantasy, but it’s not so far-fetched to imagine using cloning to accomplish more modest goals, such as duplicating select animals from select populations to keep certain genetic lineages alive. Cloning could help us maintain species in captivity until we can restore their habitats or add crucial genes back into a group of animals about to be released into the wild. Cloning won’t be a cure-all, but given the state of the planet, it can’t hurt to have options.

That’s why frozen zoos represent the ultimate safety net, a genetic savings account for the future.
*
A century from now, scientists might have cloning down pat, or they might have an even better way to bring these cellsicles back to life. One tantalizing possibility involves stem cells, which can morph into any of the body’s specialized cell types. Take a stem cell from an African wildcat and you may be able to coax it, in the laboratory, to grow into brand-new eggs or sperm. Scientists have managed to take the frozen skin cells of two highly endangered species—the white rhinoceros and the drill (a monkey)—and transform them into stem cells. The next step is to turn these cells into sperm and eggs, and then create test-tube rhinos and drills. The approach may turn out to be more efficient than cloning or a better option for species in which nuclear transfer has proved difficult. What’s more, because using eggs and sperm to create new embryos leads to genetic remixing, it will yield rhinos with new combinations of genes and should be a better way to maximize genetic diversity. This stem cell work is still in early stages, but Dresser is thrilled by the promise it holds. “I may not live long enough to see some of the stem cell stuff applied to tigers or lions or elephants,” she says, “but that’s okay, because somebody had to start that process.”

After spending years pioneering so many lab techniques, Dresser is passing the torch to the next generation of researchers, moving out from behind the microscope and into a more public role. She wants to make a forceful case for the need to develop reproductive technologies for endangered species—and to do so before it’s too late. She’s been traveling all over the country and batting ideas around with other experts. She’s visited labs that specialize in livestock breeding and talked with scientists about how their research might be applied to more exotic animals.

The technology is moving quickly, and wildlife biologists have to stay on their toes. Breakthroughs in any number of fields—livestock breeding, companion animal medicine, human reproductive technology—can spark strategies for saving endangered animals. Even advances in computing and electronics could play a role: Just ask the brigade of biologists who are fighting for threatened species with an arsenal of high-tech tracking devices.

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