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Abstract
The bucardo mountain goat of the Pyrenees had teetered at the edge of extinction for years, its numbers dwindling ever lower, until January 2000, when the last of its kind was killed by a falling tree in the protected habitat of Spain's Ordesa National Park. But unlike the woolly mammoth, the Tasmanian tiger, and other species relegated to the dustbin of time, the bucardo, noted for its protective coat of hair against the frigid mountain air, will get a second chance.
| ACT will raise the bucardo from its evolutionary grave. |
The Spanish government, in collaboration with a diverse group of scientists, had the foresight to retrieve and freeze bucardo tissue before the last animal died. Now, with the help of a Worcester, Massachusetts, company called Advanced Cell Technology (ACT), conservationists will use that preserved tissue to clone the world's last bucardo, giving the species an unprecedented chance to come back from beyond the evolutionary grave.
"In the past, extinction has meant that an animal would be gone forever," says Robert Lanza, vice president of medical and scientific development at ACT. "But the new technologies mean we can bring these species back from the brink." Indeed, after the female bucardo is cloned, Lanza envisions the creation of a male version through further genetic manipulations, making possible a true bucardo community up the road.
| An endangered species has been successfully cloned. |
ACT's work with the bucardo, moreover, follows fast on the heels of another effort, the first ever successful cloning of an endangered species, in this case a wild Asian ox called the gaur. Reported in the October 2000 edition of the journal Cloning, the gaur effort also marked the first time scientists had ever transferred the genes from one mammalian species to the egg cell of another and managed to bring the resulting embryo to term.
To accomplish this feat, the ACT team of scientists removed an egg cell from a common dairy cow and then sucked the genetic material from its center. At the same time, they acquired a gaur skin-cell culture from San Diego's Frozen Zoo, a collection of cryogenically preserved and genetically intact tissue representing hundreds of species from around the world. The gaur skin cell, with its nucleus of genetic material intact, was placed next to the enucleated cow's egg. Later, the gaur genes were fused to the cow egg through application of a mild electric current, and a fertile embryo was the result. The embryo was allowed to develop to about a hundred cells in the lab and then implanted in the cow serving as surrogate mother, which carried it to term.
| The guar was cloned using cells from the Frozen Zoo. |
The gaur that donated the skin cell, dead around seven years at the time of the cloning, had never reproduced - thus, scientists reasoned, it would replenish the species' diminishing gene pool with a novel set. Moreover, says Kurt Benirschke, former president of the Zoological Society of San Diego and founder of the society's Frozen Zoo, "we were able to examine the donor's chromosomes beforehand to make sure they were normal and completely intact. Some individuals in endangered species have damaged genetic material," explains Benirschke, "and using cells from the frozen zoo enables us to make sure we are eliminating these gross genetic errors instead of passing them on."
The cloned gaur, named Noah, was born in January 2001 "healthy and completely normal, bellowing, ears twitching, with big blue eyes," Lanza reports. Although little Noah ultimately succumbed to a common and deadly bacterial infection unrelated to the cloning, the project served as proof of the concept: Endangered species could be stored on ice for years in the form of ordinary skin cells, then brewed to embryonic perfection in the enucleated egg of a more common beast. Ultimately, those embryos could be carried to term in the womb of a similar species without further stressing endangered females through the rigors of pregnancy and birth.
| "We had to find another way." |
According to Betsy Dresser, senior vice president for research at the Audubon Institute and director of the Audubon Institute Center for Research of Endangered Species and the Freeport-McMoRan Audubon Species Survival Center, all in New Orleans, the arsenal of reproductive technologies, including cloning, could mean salvation for thousands of endangered animal species on Earth. "When I started in the zoo business almost 35 years ago," says Dresser, "we got our animals out of the wild and didn't need to think about breeding them in captivity. But as habitats were destroyed and the movement of animals restricted, we had to find another way."
That they did. Through the years, tapping techniques first developed to enhance breeding in the agriculture industry, biologists have taken the zoo from what Dresser calls a "menagerie mentality" to the state-of-the-art conservation centers they are today. It was about 25 years ago that Dresser and colleagues modified cattle-restraining techniques to collect sperm from endangered males and artificially inseminate endangered females. By the early eighties, the zoo-based scientists - again following the lead of their counterparts in agriculture - were collecting embryos from endangered species and gestating them in more common ones. A holstein cow carried a gaur, for instance, and a common eland (antelope) carried an endangered bongo calf to term. By the late 1980s, zoo researchers had learned to freeze the embryos they harvested, enabling them to transport endangered animals around the world in containers the size of a thermos bottle. Then in the 1990s, zoo conservationists along with the rest of the world discovered the miracle of in vitro fertilization, in which embryos are created in the test tube instead of a living womb. Dresser herself was involved in the creation of the first test-tube gorilla, named Timu, in 1995.
| Zoos have evolved from menageries to conservation centers. |
Putting the techniques together, Dresser was also at the helm of the groundbreaking team that, in 1999, froze and then thawed the embryo of an endangered African wildcat and implanted it in the womb of a common domestic cat. The frisky kitten, named Jazz, represented the first "inter-species frozen-thawed embryo transfer" brought to term. Eventually Dresser realized that cloning would be the next embellishment in the zoo-based "tool kit" of assisted reproductive technologies to rescue endangered species from extinction.
Part of the new steam derives from a related effort to clone common cats and dogs. ACT, for instance, is now working to clone dog guides for the blind, hearing dogs for the deaf, search-and-rescue dogs for police departments, and a range of pets for use in various psychotherapies. Working with Louisiana State University, meanwhile, Dresser and the Audubon Institute have joined a company called Lazaron BioTechnologies to clone pet dogs and cats.
| Cloning pets with specific personality traits is the Holy Grail. |
For industry, explains Dresser, cloning pets with specific personality traits is the Holy Grail, a surefire route to profit. For conservationists such as Dresser, the knowledge gained by working with dogs and cats will aid in the cross-species transfer and cloning of tigers and other endangered wild cats and wolves. An understanding of felines, for instance, could facilitate the cloning of the cheetah, with only 12,000 individuals left in the wild today. "We can't clone endangered species unless we have common species to transfer them into," Dresser states. And each transfer is complex, involving not just knowledge of specific times and temperatures for freezing and thawing tissue and embryos, but also detailed knowledge of the reproductive traits of the surrogate mother's species.
Benirschke, who believes his frozen zoo and others like it may become the final refuge for endangered animals, notes that many species will have to be kept on ice while researchers study the reproductive physiology of potential hosts. "The host animal must be compatible in terms of length of gestation, hormonal environment, and even size and shape of the placenta," he explains. "We just received tissues from a group of bush pigs, which are related to hogs. We can do studies to see whether that transfer will work." Other matches Benirschke may study include the possibility of gestating the endangered gorilla in a chimp or orangutan; the zebra in a horse or a donkey; and the macaque in a common rhesus monkey. "Cloning the endangered panda may be particularly difficult," he notes, "because it's dubious as to whether a bear or any other common species could serve as compatible host."
| The long-extinct woolly mammoth resisted cloning. |
Even as Dresser and Benirschke resolve the fine points of cloning and cross-species birth for endangered species, others are trying to bring back animals that have been extinct for years. Back in 1999, for instance, researchers unearthed a woolly mammoth frozen and preserved in the Siberian plains for almost 20,000 years. Their efforts to clone the creature were thwarted, however, because it had frozen and thawed so many times its DNA was irreparably damaged. Another team hopes they'll have better luck with the Tasmanian tiger, a marsupial that in 2001 had not been seen on Earth for 65 years. Pointing to a 135-year-old fetus preserved in alcohol at Sydney's Australian Museum, researchers say they will try to "unscramble" the creature's damaged DNA. Because "waking" the "sleeping fetus" would require not just cracking its genetic code but also constructing a synthetic cell in which the genes could live, the scientists estimate the cost of resuscitation at tens of millions of dollars and two decades of work - if it can be done at all. In light of this, it hardly seems likely that we will soon fulfill the vision of Jurassic Park - the movie itself now optimistically cloned into sequel number three - and engineer the return of Tyrannosaurus rex.
The point is best made, perhaps, through the subtext of one edgy Web site with the eye-popping Internet address of Clonejesus.com, allegedly supported by the nonprofit group "The Second Coming Project," devoted to the resurrection of Christ through DNA in the holy shroud. While Clonejesus.com is likely just a joke, its message is critical: We may never clone God, but the new technology invests us with godlike power over the creatures of the Earth.
| Cloning may be the last hope for many endangered species. |
At first glance the ethics of cloning endangered species seem clear-cut, free of the sticky war now embroiling human cloning - where the procedure evokes chilling images of "Big Brother" and challenges not just religious beliefs but also our sense of self. "In the case of endangered species, we are often talking about groups that have ten or perhaps 25 living members," Betsy Dresser explains. "At that point cloning and associated reproductive technologies are their last best hope."
Yet some skeptics say this do-good ethic is misguided, a scientific guilt trip heedless of Darwin's law that only the fit survive. Reviving these species, say the critics, amounts to torture of evolution's rejects, animals now so out of synch with the altered Earth that they can exist only as curios in man-made museums of the bizarre. If the money is spent on anything, they add, it should be on saving habitats so that remaining animals can have a natural home; and even where habitats remain, wouldn't cloned animals just serve to homogenize a species, weakening genetic diversity as hundreds or thousands of copies of a single individual are unleashed at once?
| Cloning restores genes to the gene pool. |
But Lanza, Dresser, and other conservationists in favor of cloning say the critics have got it all wrong. Lanza, for instance, explains that cloning, used correctly, would increase genetic diversity, not limit it. "The goal is taking an animal that has not yet contributed to the gene pool and injecting its genes back into nature to achieve population diversity. In order to fight disease and environmental insult, species need enough genetic diversity to adapt. Every animal that dies represents a set of genes lost from the planet forever, and in populations with few remaining individuals, we can use cloning to restore those genes. We need not ever lose valuable genes from the gene pool of any species again."
On the question of cloning versus habitat preservation, Betsy Dresser says we need both. "Of course, we must save habitats," she says, "but it may be impossible to protect habitats fast enough to save most of the species about to be lost. And by not salvaging the genetic material as well, we are limiting the choices we'll have in years to come. A hundred years ago, we were in horses and buggies and now we are on the moon. What will the Earth be like 7,500 years from now - or even 50 years from now? We just don't know. The only thing we do know is that we can preserve the genetic material from these endangered species. If we preserve it properly - not like the woolly mammoth, not like the dinosaur, but intact - we can use it whenever we need. We have the power, today, to preserve the wonderful elephants and tigers that we care about, and to provide an option for the future. A hundred years from now, we could be repopulating other planets, and this frozen genetic material might be just what we need."
| Endangered species may someday stock barren planets. |
The technology Dresser advocates does seem fitting for the über Arks we may one day send across star systems. The biblical Noah built a vessel that carried actual animals. But once advanced reproductive technologies such as cloning have fully evolved, says Dresser, they will allow us to deliver species in the form of frozen cells - or perhaps even genetic code on a chip - for reconstitution on site. Whether on Earth or on some other world, Dresser emphasizes, "this will only happen if we do the work of preservation now, because once the animals are gone, it will be too late."
Pamela Weintraub is a former staff writer at Discover, former editor-in-chief of Omni Internet, and the author of 15 books on health and science.
Susan Wolsborn is Web designer of HMS Beagle.
Can Cloning Save Endangered Species? - examines the controversy surrounding efforts to clone some endangered and even extinct species. Current Biology, 2001, 11:7:R245-R246. Full text available from BioMedNet.
Gaur Power - offers additional information on Advanced Cell Technology and the cloned guar. From Current Biology, 2000, 10:22:R812. Full text available from BioMedNet.
DNA Banks for Endangered Animal Species, Preservation of DNA From Endangered Species, and Cloned Gaur a Short-Lived Success - several recent articles from Science focus on cloning endangered species.
Cloning Noah's Ark - argues that biotechnology might be the best way to keep some species from extinction. From the November 2000 issue of Scientific American.
Biotechnology and Endangered Species - listen to the April 20, 2001 broadcast of Science Friday. Includes related links.
Cloning for Survival: Australian Clone Work Targets Endangered Species- a recent article from ABCNEWS.com on the use of cloning for species preservation.
Cloning and Stem Cells - keep abreast of the latest news with this special report from New Scientist.
Cloning - the Roslin Institute's site on cloning and nuclear transfer.
Cloning of Endangered Animals - a comprehensive site authored by college student Megan Kate Schufreider.
Cloning Is No Extinction Panacea - a look at the ethics of cloning endangered species.
Introduction to Cloning - an overview of cloning and the ethics of cloning prepared by Aaron Hawley.
Nuclear Transfer - a general overview of the science of cloning.
Related HMS Beagle articles:
- DNA Banks: Noah's Ark at -200 °C - focuses on using DNA and frozen cells from endangered species to enhance conservation efforts.
- Cataloging the Web of Life - a collection of online biodiversity sites.
- Evolution Meets Conservation at the Brink of the Homogocene - reviews a recent meeting that discussed evolution and the loss of biodiversity.
- Critical Biodiversity - looks at using ecosystem models to better preserve species biodiversity.
- Cloned Creations - a discussion of cloning sites on the Web. Cloned Creations - a discussion of cloning sites on the Web.