Natural Acts

by David Quammen

  The news item, drawn from wire services, was only a column filler that didn’t offer much detail. It barely alluded to the central question: Why clone a deer? It mentioned that Dewey had been born back in May, seven months earlier, his existence kept quiet pending DNA tests to confirm his identity as an exact genetic copy. That settled, he could now be presented to the world. Dr. Mark Westhusin, of the College of Veterinary Medicine at Texas A&M, spoke for the team that created the fawn, explaining fondly that Dewey had been “bottle-fed and spoiled rotten his whole life.” The item noted that A&M, evidently a leading institution in the field, had now cloned five species, including cattle, goats, pigs, and a cat.

  One other claim in this little report (which had the flavor of a reprocessed press release) went unexamined and unexplained: “Researchers say the breakthrough could help conserve endangered deer species.” Seeing that, I began planning a trip to Texas.

  The notion that cloning might help conserve endangered species has been bandied about for years. Very little such bandying, though, is done by professional conservationists or conservation biologists. One lion biologist gave me a pointed response to the idea: “Bunkum.” He and many others who study imperiled species and beleaguered ecosystems view cloning as irrelevant to their main concerns. Worse, it might be a costly distraction, diverting money, diverting energy, allowing the public to feel some bogus reassurance that all mistakes and choices are reversible and that any lost species can be recreated using biological engineering. The reality is that when a species becomes endangered, its troubles are generally two-fold: not enough habitat and, as the population drops, not enough diversity left in its shrunken gene pool. What can cloning contribute toward easing those troubles? As for habitat, nothing. As for genetic diversity, little or nothing, except under very particular circumstances. Cloning is copying, and you don’t increase diversity by making copies.

  Or do you? This assumption, like the one about cheap deer, turns out to merit closer scrutiny.

  The people most bullish on cloning are the cloners themselves, a correlation that’s neither surprising nor insidious. They don’t call themselves “cloners,” by the way. Their résumés speak of expertise in reproductive physiology and “assisted reproductive technologies,” a realm that stretches from human fertility medicine to livestock improvement and includes such tasks as in vitro fertilization (IVF, as it’s known in the trade), artificial insemination (AI, not to be confused with artificial intelligence), sperm freezing, embryo freezing, embryo transfer, and nuclear transfer (which refers to the information-bearing nucleus of a cell, where the chromosomes reside, not the energy-bearing nucleus of an atom). There’s also a process called ICSI (pronounced “icksy”), meaning intra-cytoplasmic sperm injection, helpful to elderly gentlemen whose sperm cells can no longer dart an egg with the old vigor. The collective acronym for all such assisted reproductive technologies is ART. To its practitioners, cloning is just another tool in the ART toolbox.

  These ARTists are smart, committed people. Like others who feel a vocational zeal, they do what they believe in and believe in what they do. Blessed is the person so situated. But in their enthusiasm for cloning research, in their need to justify their time and expenditures to boards of directors, university deans, and the public, they send their imaginations to the distant horizon for possible uses and rationales. See what cloning could do for you, for society, for the planet? Some of the applications they propose are ingenious and compelling. Some are tenuous and wacky. Three of the more richly peculiar ones, each fraught with complexities and provocations, are cloning endangered species, cloning extinct species, and cloning pets. College Station, Texas, home of Dewey the duplicate deer, is where I picked up the sinuous trail that interconnects them.

  “So this guy brought these testicles to me,” says Mark Westhusin, as we sit in his office at Texas A&M’s Reproductive Sciences Laboratory, on the edge of campus. The testicles in question, he explains, came from a big whitetail buck killed on a ranch in south Texas. The fellow had got hold of them from a friend and, intending to set himself up as a “scientific breeder,” hoped that Westhusin could extract some live semen for artificial insemination of his does.

  Westhusin, an associate professor in his mid-forties, is an amiable man with a full face and a fashionably spiky haircut. He has already explained to me about “scientific breeders,” the term applied to anyone licensed by Texas for the husbandry of trophy-quality deer. Deer breeding is a serious business in Texas, where the whitetail industry accounts for $2.2 billion annually and where open hunting on public land is almost nonexistent, because public land itself is almost nonexistent. Most deer hunts here occur on private ranches behind high fences, allowing landowners to maintain—and to improve, if they wish—their deer populations as proprietary assets. Texas contains about 3.5 million whitetails, some far more valuable than others. An affluent hunter, or maybe just a passionate one, might pay $20,000 for the privilege of shooting a fine buck. A superlative buck, a giant-antlered prince of the species, can be worth $100,000 as a full-time professional sire. And the market doesn’t stop at the Texas border. Westhusin has heard of a man who had a buck—it was up in Pennsylvania or someplace—for which he’d been offered a quarter million dollars. He didn’t take it, because he was selling $300,000 worth of that buck’s semen every year. Such an animal would be considered, in Westhusin’s lingo, “clone-worthy.”

  Now imagine, Westhusin tells me, that they’re collecting semen from that deer one day, and the deer gets stressed, and it dies. Damn. So what do you do? Well, one answer is you take cells from the dead buck and then clone yourself another animal with the same exact genotype. While you’re at it, you might clone four or five.

  “You’re certainly not going to go out and clone any old deer just for the sake of cloning it,” he says. Then again, when you’re practicing—when you’re developing your methods on a trial basis—you won’t wait for the Secretariat of whitetails. The buck from south Texas, the one whose testicles landed in Westhusin’s lab, wasn’t superlative but it was good, and the experiment evolved haphazardly.

  Working with his students to extract the semen, Westhusin suggested also taking a skin sample from the buck’s scrotum, on the chance they might find a use for it. “We’ll grow some cells,” he said, “and maybe later on, if we have the time and the money, we’ll do a little deer-cloning project.” Eventually the effort produced a few dozen tiny embryos, which were transferred into surrogate does, resulting in three pregnancies, one of which yielded a live birth. That was Dewey, born May 23, 2003, to a surrogate mother known as Sweet Pea. The donor buck remained nameless.

  The fellow who brought in the testicles remains nameless too, at least as the story is told by Mark Westhusin. “People don’t want it to get out that they’ve got these huge, huge deer on their ranch. Because then the poaching gets so bad.” Down in south Texas, people circle their land with high fences not just to keep the deer in but to keep the poachers out.

  Dr. Duane C. Kraemer, a senior scientist and professor at the Texas A&M veterinary college, is also sometimes called Dewey, though not by visiting journalists or staffers reluctant to presume. He’s a gentle, grandfatherly man with pale eyes and thinning hair, whose casually dignified style runs to a brown suit and a white pickup truck. His ART specialty is embryo transfer, and that’s the step he oversaw on the deer-cloning project.

  Kraemer was the mentor of Mark Westhusin, who did his doctorate at A&M and then worked for several years in the private sector before returning as faculty. The relationship between academic reproductive physiologists and the livestock business tends to be close, even overlapping, because this is a practical science. There’s money in assisting the reproduction of elite bulls, cows, and horses, and that money helps fund research. Kraemer himself, raised on a dairy farm in Wisconsin, has been at A&M for much of the past fifty years, during which time he took four degrees, including a Ph.D. in reproductive physiology and a D.V.M., and performed the firs
t commercial embryo transfer in cattle.

  Working on yellow baboons, a more speculative project with implications for human medicine, he did the first successful embryo transfer in a primate. He also did the first embryo transfer in a dog and the first in a cat. Embryo transfer isn’t synonymous with cloning—the embryo being transferred needn’t be a clone—but it’s a necessary stage in the overall cloning process. Within that specialty, and beyond it, Kraemer has been a pioneer. In the late 1970s, he and colleagues engineered the birth of an addax, a rare African antelope, using artificial insemination with sperm that had been frozen. People at the time asked: Why work with addax? The species, Addax nasomaculatus, didn’t seem endangered. Now it’s extinct everywhere except for a few patches of desert in the southern Sahara. After five decades of quietly working the boundary zone between veterinary medicine and reproductive science, Kraemer is one of the patriarchs of the ART field. Dewey the deer was named in his honor.

  For Kraemer, the impetus to work with wildlife came partly from his students, some of whom asked him to teach them skills that might be applied to endangered species. Semen freezing and artificial insemination were proven techniques twenty-five years ago. Embryo transfer and in vitro fertilization showed great promise. Cloning—that was a dream. Kraemer had some small grants to support the student training, but after graduation his young people faced poor odds of landing a job in wildlife or zoo work. “We had told them right up front,” he says, “‘You better have another way of making a living, and you may have to do this on the side.’” Mark Westhusin, for one, took a job doing research for Granada Bio-Sciences, part of a large cattle company.

  Kraemer meanwhile established an effort he called Project Noah’s Ark, aimed at putting students and faculty into the field with a mobile laboratory. The lab, in a 28-foot trailer, was equipped for collecting ova, semen, and tissue samples from threatened populations of wild animals in remote settings, such as the desert bighorn sheep in west Texas. The project’s three purposes were to train students, to research techniques, and to preserve frozen tissue samples for possible cloning. At present the trailer contains a surgical cradle capable of holding an anesthetized bighorn, a portable autoclave (for sterilizing instruments), a laparascope with fiber optics (for extracting ova from ovaries), three 50-amp generators, and an earnest sign: “Ask not only what Nature can do for you, but also what you can do for Nature.—D. C. Kraemer.” Asking what he could do for Nature by way of assisted reproductive technologies didn’t bring Kraemer much financial support. The training has gone forward, but the ark itself is in dry dock.

  Animal cloning began, back in 1951, with frogs. Robert Briggs and Thomas J. King were embryologists based at a cancer research institute in Philadelphia, with a medical interest in understanding how genes are turned on and off during embryo development. Briggs, the senior man, figured that a cloning experiment might bring some insight. What he envisioned was transferring the nucleus of a frog cell, taken from an embryo, into an enucleated frog egg—that is, one from which the original nucleus had been scooped out like the pit from an olive. King, hired for his technical skills, would do the micromanipulation, using delicate scissors and tiny glass needles and pipettes. The transferred nucleus would contain a complete set of chromosomes, carrying all the nuclear DNA required for guiding the development of an individual frog. If things went as hoped, the reconfigured egg would divide into two new cells, divide again, and continue dividing through the full course of embryonic growth to yield a living tadpole. From 197 nuclear-transfer attempts, Briggs and King got 35 promising embryos, of which 27 survived to the tadpole stage. Although the success rate was low, barely one in eight, their experiment represented a large triumph. They had proved the principle that an animal could be cloned from a single cell.

  Two questions followed. First, could it be done with mammals? Second, could it be done not just from an embryo cell, as DNA donor, but from a mature cell snipped off an adult? The second question is weighty, because cloning from embryo cells is, except under special conditions, cloning blind. If you don’t know the adult character of an individual animal—is it healthy, is it beautiful, is it swift, is it meaty, does it have a huge rack of antlers?—why take pains to duplicate it?

  For decades both questions remained in doubt. Nobody succeeded in producing a documented, credible instance of mammal cloning. One researcher claimed to have cloned mice, but his work fell under suspicion, and it could never be verified or repeated. In 1984 two developmental biologists went so far as to state, in the journal Science, that their own unsuccessful efforts with mice, as well as other evidence, “suggest that the cloning of mammals by simple nuclear transfer is biologically impossible.”

  Well, no, it wasn’t—as proved that very year by a brilliant Danish veterinarian named Steen Willadsen. Unlike the developmental biologists who experimented with frogs or laboratory mice, but like Kraemer and Westhusin, Willadsen focused on farm animals. Working for the British Agricultural Research Council at a laboratory in Cambridge, he achieved the first verified cloning of a mammal. He did it—a dozen years before the famously cloned bovid, Dolly—with sheep. He took his donor cells from early sheep embryos, which had not yet begun to differentiate into the variously specialized cells (known as somatic cells) that would eventually form body parts. Such undifferentiated cells, it seemed, were crucial. Transferring one nucleus at a time into one enucleated ovum, fusing each pair by means of a gentle electric shock, following that with a few other crafty moves, Willadsen got enough viable embryos to generate three pregnancies, one of which yielded a living lamb. The following year, afloat on his reputation as a cloner, he left Cambridge for Texas, hired away by the same cattle company, Granada, that soon afterward would also hire Mark Westhusin.

  “And so,” Duane Kraemer says, “Dr. Willadsen then came and taught us how to do cloning.”

  But Willadsen couldn’t teach them to clone an animal from a skin sample sliced off a buck’s scrotum, because he hadn’t solved the special problems of cloning from somatic cells. Between early embryo cells (which all look alike) and somatic cells (specialized as skin, bone, muscle, nerve, or any sort of internal organ) lurks a deep mystery: the mystery of development and differentiation from a single endowment of DNA. Each cell in a given animal carries a complete copy of the same chromosomal DNA, the same genetic instructions; yet cells respond differently during development, fulfilling different portions of the overall construction plan, assuming different shapes and roles within the body. How does that happen? Why? What tells this cell to become skin, that cell to become bone, another to become liver tissue? What signals them to implement part of the genetic instructions they carry and to ignore all the rest? Big questions. Cloning researchers, if they were ever to produce an animal cloned from an adult, didn’t necessarily need to answer those questions, but they needed to circumvent them. They needed somehow to erase the differentiation of the donor DNA and to conjure it into operating as though its role within a living creature had just begun anew.

  That’s what Ian Wilmut, Keith Campbell, and their colleagues in Scotland managed in 1996, using some further touches of biochemical trickery. The result was Dolly, her existence revealed in Nature the following year. Dolly’s donor cell came from the udder of a six-year-old Finn-Dorset ewe. Her birth was significant because it meant that cloners could now shop before they bought.

  Lou Hawthorne, a cagey businessman with a trim beard, a weakness for droll language, and a soft heart for animals, tells me how the notion of dog cloning arrived at Texas A&M. Hawthorne is the CEO of a California-based company called Genetic Savings & Clone, which offers the services of “gene banking and cloning of exceptional pets.” Another man, Hawthorne’s chief financial backer, who prefers to avoid media attention, set the process in motion with a personal whim. “It was just one morning, he was reading the paper,” says Hawthorne. “Dolly had been cloned. There was an article about it, and he said: ‘I think I’d like to clone Missy. I can afford it.’
”

  The “he” refers to John Sperling, founder of the Apollo Group, a $2 billion empire that encompasses, among other things, the University of Phoenix, a lucrative enterprise in higher education for working adults. Missy was ten years old at the time of Sperling’s brainstorm, a dog of unknown lineage but winning charms, adopted from a pound. Asked by Sperling to make inquiries, Lou Hawthorne solicited proposals from a dozen laboratories; the best came from Texas A&M.

  Westhusin remembers telling Hawthorne that they could give it a try but that trying might cost a million dollars a year, take five years, and still be uncertain of success. Okay, said Hawthorne. John Sperling, as he himself had declared, could afford it. So the R&D effort toward producing a duplicate Missy—or maybe a multiplicity of copies—began at College Station in 1998. Hawthorne, a word man among scientists, named it the Missyplicity Project.

  At the start it was a joint venture between Texas A&M and an earlier company led by Hawthorne, the Bio-Arts and Research Corporation. Missy contributed a patch of skin cells, which were multiplied by culturing in vitro and then frozen for future use. Westhusin’s team gathered a pool of female dogs to serve as egg donors. The eggs, harvested surgically from the oviducts whenever a dog showed signs of ovulation, were emptied of their nuclei using micromanipulation tools (tiny pipettes guided by low-gear control arms within the field of a binocular scope) and then refitted with Missy’s DNA by nuclear transfer. These refitted cells were nurtured in the laboratory until some of them showed good embryonic development. Promising embryos were then implanted surgically in ready (that is, estrous) surrogate mothers. Among the factors that make dog cloning difficult is that female canines come intro estrus irregularly. Unless you’re keeping a riotous kennel, you may not have a bitch in heat when you need her. Westhusin and his Missyplicity partners struggled against that limitation and others for almost five years.