Interspecies Cloning
Dinosaurs on Earth?
Less than a decade ago director Stephen Spielberg brought brachiosaurs, tricerotops, velociraptors, and a ferocious yellow-eyed Tyrannosaurus Rex to life in Jurassic Park after millions of years of extinction. There were critics who blasted the film’s premise for being scientifically far-fetched. One such critic was James Berardinelli: "Given the current state of technology, the situation postulated in Jurassic Park cannot happen...the necessary cloning techniques [do] not exist" Now, as the world anxiously awaits the birth of the first cloned endangered animal to gestate in the womb of another species, a land populated with once-extinct dinosaurs seems frighteningly plausible.
The Asian Gaur
In a matter of weeks, an ordinary cow named Bessie will be the first animal in history to give birth to a cloned member of a different species. Perhaps even more awesome is the fact that Bessie will be birthing an endangered Asian gaur named Noah who was cloned from a skin cell taken from a deceased gaur.
Standing over six feet high at the shoulders and weighing as much as 2,200 pounds, gaurs are considered the largest of wild cattle. Unfortunately, these massive, hump-backed bovines are quickly disappearing. For decades, the survival of the gaur species has been threatened by hunters who kill these one-ton animals for sport. Furthermore, the habitats of the Asian gaurs--the forests, jungles and grasslands of India, southeast Asia, and Indochina--have diminished to the point where the once-abundant Asian gaurs have dwindled to a mere 36,000 (Link: Scientific American, November, 2000, p. 84) Young Noah offers perhaps the best hope scientists currently have at preserving and possibly repopulating the rare gaur species.
Conservation vs. Cloning Controversy
Many scientists acknowledge that cloning invites a host of ethical and scientific dilemmas. In this case the controversy is exacerbated by the fact that the animal being cloned is heading toward extinction. Opponents believe that cloning is not a panacea for endangerment or extinction, and instead urge scientists to look at why an animal is endangered—how is it being exploited and what is threatening its natural habitat. "Cloning would provide us with individual animals but not the home to introduce them to in the wild," says Jeff Flocken, endangered species outreach coordinator at the National Wildlife Federation. "Whatever's causing a species to decline, whether it's exploitation or destruction of a habitat, would continue to put that species at risk of being exterminated." It is feared that even if scientists could encourage species revitalization through cloning, many of the cloned animals whose natural habitat has been destroyed would only be able to survive in zoos. Some critics assert that if cloning endangered species becomes commonplace, herds of animals with identical genetic compositions could inhabit the earth. These cloned animals would lack the genetic diversity critical for their survival, and would be severely compromised in their ability to adapt to new evolutionary pressures. This could possibly lead to a dependence upon cloning for a species continued existence.
Robert P. Lanza, the Vice President of Medical and Scientific Development at Advanced Cell Technology (ACT), the company responsible for the cloning of Noah, has a far different perspective on the scientific advances in cloning than many of the critics. "One hundred species are lost every day, and these mass extinctions are mostly our own doing," Lanza said. "Now that we have the technology to reverse that, I think we have the responsibility to try." Betsy Dresser, Director for Research of Endangered Species in New Orleans, concurs with Lanza. "As scientists in the area of conservation, we're obligated to use as many tools as we can."
Interspecies Nuclear Transfer - Cloning Noah
The process of nuclear transfer and subsequent cloning is not very efficient, or only few clones out of many make it to a healthy birth. To produce viable embryos, almost 700 gaur skin cells were used to fuse with cow eggs by Lanza and his colleagues. Grown in the n the laboratory, only 81 of these embryos grew to sufficient size to be planted in 32 surrogate mothers. Out of these, a mere eight became pregnant. The scientists removed two fetuses for analysis, five of the pregnancies ended in miscarriages. Noah, was the sole survivor of this cloning attempt. His birthdate will likely be late November, 2000.
What Lies Ahead in Species Preservation
As the scientific community sits poised to welcome Noah to the world, we wonder what other animals will soon join the menagerie of cloned animals. As a sort of insurance plan against extinction, zoos across the globe are beginning to collect and freeze tissue from endangered animals in the hopes that some day the tissue can be used to clone and thereby rebuild a dwindling population of animals.
More specifically, scientists at ACT are laying plans to employ the nuclear transfer process to clone a giant panda bear. They hope to use frozen cells from the National Zoo’s late pandas, Ling-Ling and Hsing-Hsing, along with eggs extracted from female black bears killed during the hunting season, to generate cloned giant panda embryos. The embryos will then be implanted into a surrogate black bear mother. The hope, of course, is to repopulate the number of pandas living in the wild, which is presently thought to be less than 1,000.
At the Audubon Institute Center for Research of Endangered Species (AICRES), researchers are working to rebuild the endangered mountain subspecies of bongo antelope. While the vast majority of the mountain bongo (about 550) currently live in captivity, reports indicate that there could be as few as 50 of the striped antelope living in their natural habitat of Kenya. AICRES scientists in Kenya are attempting to transfer frozen bongo embryos into fairly common African antelopes called elands for gestation.
Dinosaurs on Earth in the New Millenium?
With all of the recent optimism surrounding the cloning of endangered animals, questions arise as to the viability of bringing extinct animals back to earth. In 1999, for example, researchers unearthed a wooly mammoth in Siberia that had been preserved in the frozen plains for nearly 20,000 years. Unfortunately, because the tissue of the wooly mammoth had been repeatedly frozen and thawed for thousands of years, the mammoth’s DNA was severely damaged. Presently, molecular biologists are uncertain about how to fill in genetic gaps and do not know if the creature’s remains contain sufficient amounts of DNA to successfully proceed with a cloning attempt.
Plans to clone a now-extinct bucardo mountain goat are expected to meet with greater success. Unlike the case of the wooly mammoth, Spanish scientists working with the bucardo mountain goat were able to extract and preserve a live tissue specimen from the last known member of the species before she was killed by a falling tree limb in Spain’s Ordesa National Park. ACT scientists, in collaboration with agricultural researchers and government officials in Spain, intend to use interspecies transfer cloning--the same method used to impregnate Bessie--to implant the bucardo into a more common goat for gestation. The team expects to welcome the bucardo mountain goat back to earth in the summer of 2001. Unfortunately, even if the interspecies cloning process is successful, it is questionable as to whether the bucardo population can ever be regenerated because scientists presently only have tissue from a female. However, ACT hopes to solve this problem by manipulating the chromosomes to make a male.
Do the fantastic advances in the interspecies nuclear transfer process mean that we should prepare for the day when our cars are chased and overturned by a ravenous dinosaurs, such as the magnificent T-Rex? By most accounts, the answer is no. That is, of course, unless there exists somewhere on earth a treasure of dino-DNA preserved for millions of years. For now, let’s just be thankful that baby Noah, the world’s newest cloning success, likes to munch mostly on grasses and bamboo shoots, not people.
Update on Noah Since the Release of this Article
Despite a successful delivery, Noah died just two days after making history as the first animal to gestate in the womb of another species. After performing a necroscopy on the gaur, scientists determined that the young bull died from dysentery—a very common cause of death in farm animals—not from complications arising from interspecies cloning or gestation. Researchers involved in the cloning efforts remain hopeful about the prospects of cross-species cloning and are working on several similar projects.
Interspecies Cloning Web Site Links
Scientific American - article on cloning endangered species
Scientific American -Provides an overview of cloning
Advanced Cell Technology - homepage
Time Magazine -- Contains a five picture sequence with audio describing each step in the cloning process used to clone Dolly.
The Ultimate Ungulate – Great website containing information on the Asian gaur, as well as other ungulates
Infigen Corp. -- Website on commercialized applications of cloning technologies in the cattle breeding, pharmaceutical, nutraceutical and xenotransplantation fields
Roslin Institute - home page
Colossus.net -- Movie review of Jurassic Park