CLONING Hit or Miss?

Some scientist want to save endangered species by genetically duplicating them. But will this risky process work?

Last January, an ordinary Iowa milk cow named Bessie delivered a healthy baby gar, or rare wild Asian ox, named Noah. Talk about separated at birth--was this some freak of nature? No, Noah became the first endangered species ever to be cloned, or genetically duplicated, and carried to term in the womb of another species.

Scientists were elated by Noah's birth. After gradual destruction of gaur habitats in the bamboo jungles of Southeast Asia, only about 36,000 of the oxen remain in the wild. Could cloning Noah signal a new strategy to rescue endangered species, like the giant panda or Sumatran tiger--and even revive such extinct species as the wooly mammoth?

Excitement over Noah soon tanked: At two days old the calf died of scours, chronic diarrhea in livestock caused by an intestinal infection. "Scours isn't unheard of in calves, but it's not the most common cause of newborn death either," says Jerome Van Biervliet, a veterinarian at Cornell University in Ithaca, N.Y. As a result, some skeptical researchers questioned whether the actual cloning process may have played a role in Noah's death. While there may never be a final verdict, one thing seems certain: Noah's brief life is a rocky start to a new era in cloning.

Ever since Dolly--the first lamb cloned from an adult sheep cell, not from an embryo--grabbed headlines in 1997, scientists around the globe have made remarkable leaps in creating perfect genetic copies of adult cows, mice, pigs, and goats. Cloning advocates claim the process can produce animals able to manufacture human medicines in their milk, provide higher quality meat, or even offer organs better adapted for human transplants.

SAVING SPECIES

Cloning is also the latest tool in the battle to salvage the world's vanishing creatures. "The human race has casually used technology to destroy other species," says Michael West, president of Advanced Cell Technologies (ACT) in Worcester, Mass., the biotechnology company that created Noah. "Now we're using cloning technology to try to save them."

But not all scientists think it's a good idea. "We don't believe cloning has any relevance in conserving endangered species," says senior scientist David Wildt at the Smithsonian Institution's Conservation and Research Center in Front Royal, Va. Is cloning a valuable research tool that can save threatened species and aid humanity, or is it a risky and unethical strategy? Are human clones next? Clearly, the debate rages on.

IDENTICAL TWINS

Unlike the process of sexual reproduction, which produces a unique individual, cloning creates a genetically identical copy of an animal--like an identical twin. Dolly the lamb, for example, has the exact same genes, or chemical instructions in cells, as the adult sheep from which she was cloned. But cloning is a complex method: To create Noah, ACT researchers inserted a needle into a cow's egg cell and removed the nucleus (cell center). By doing so, they eliminated the cow's DNA--instructions encoded in genes that determine traits from hair color and body shape to the tendency to inherit certain diseases (see SW 10/16/2000).

Using a small electric jolt, researchers fused an adult gaur's skin cell to the cow's DNA-free egg cell (see diagram, far right). The gaur DNA then stimulated the cow's egg cell to divide and form a hollow ball of about 100 cells called a blastocyst. The blastocyst was then surgically implanted into Bessie's womb and developed into a gaur embryo (early form of a vertebrate animal). For the next 10 months, Bessie served as a surrogate (substitute) mom for Noah.

Why didn't scientists use a gaur as a surrogate mother? Since the species is so endangered, researchers consider gaurs too precious to use as experimental subjects for taxing pregnancies. Instead, they chose the less scarce Angus cow--cousin to the gaur.

HIT AND MISS

Bessie wasn't the only cow to receive a gaur blastocyst. ACT scientists fused 692 gaur cells to cow eggs, but only 81 grew into blastocysts. Scientists kept some blastocysts to study: Of the 40 implanted into 32 surrogate cows, only 8 became pregnant--and only Bessie gave birth.

With odds of 692 to 1 against Noah's birth, his death doesn't really spell a setback for the cloning process. When blastocysts are formed by normal reproduction, nearly 70 percent develop into healthy newborns. "In cloning experiments, the average success rate is only about 2 percent," says George Seidel Jr., a physiology professor at Colorado State University. And ACT scientists remain optimistic: "Noah's birth brightens the prospects that we can apply this technology to many species on the verge of extinction," says ACT researcher Philip Damiani.

RISKY BUSINESS

Still, successful cloning has a long way to go. In 1999, it took scientists in Hawaii 274 tries to generate three cloned baby mice, and last year it took researchers in Japan 110 tries before a surrogate sow gave birth to Xena--the flint cloned piglet. And baby clones are three times more likely to die than natural newborns. They often suffer from underdeveloped lungs, are larger than normal, or develop bacterial infections weeks after birth. In 1998, eight cloned calves were, born in Japan, but only four survived to their first birthday. Two of the three mice born in Hawaii died almost immediately. The sole survivor, however, named Cumulina, went on to produce three generations of clones--60 mice in all.

Like Noah, many clones seem to die of natural causes, but some scientists suspect the cloning process could render animals more susceptible h) disease. "Even a small problem early on can have unexpected consequences further downstream," says Seidel. Another concern for cloned animals: they lack genetic diversity to fight off disease. Say a scientist clones a herd of cattle. If the wrong virus infects one cow, the entire herd could be wiped out overnight. For now, at least, cloning seems to be as much of an art as it is a science.

CLONING FUTURE

In time, cloning technology will undoubtedly improve, but some researchers think endangered species shouldn't be cloned until the process is more reliable. And though a University of Kentucky researcher plans to start cloning experiments on humans, most scientists believe the technology must be foolproof before launching such controversial experiments. Plus, many researchers oppose human cloning under any circumstances (see "Should Scientists Clone Humans?").

Since Earth could lose up to 20 percent of all species known today by 2025, according to the World Wildlife Fund, how do scientists propose to save vanishing creatures? "Now that we have the technology to reverse the trend, I think we have the responsibility to try and clone them," says Robert Lanza, ACT's vice president of scientific development.

But other scientists like Wildt favor methods such as artificial insemination--in which sperm, a male sex cell, is used to impregnate a female without sexual contact--recently used to successfully breed endangered ferrets. Scientist William Holt at London's Institute of Zoology thinks the best way is to learn more about species' reproductive habits and to preserve habitats that foster natural breeding.

Still, ACT scientists have a vision. Perhaps one day technology can create clones of wooly mammoths and other extinct mammals. Yet most scientists admit they'll never be able to bring back Tyrannosaurus rex. While an Asian elephant could probably give birth to a baby mammoth, no living reptile is large enough or a close-enough relative to lay the eggs of huge dinosaurs. Plus, no viable T. rex DNA is available. Dinos may be free from cloning, but are you?

A Cloning History Timeline

Like most scientific breakthroughs, cloning is no overnight sensation. Nearly six decades of trial and error elapsed before the world cheered "Hello, Dolly!"

1938

A German scientist theorizes that animals can be cloned by fusing an embryo (early developing animal) with an egg cell.

1952

Two scientists try cloning frogs, without success.

1970

A British scientist repeats the frog experiment. He transplants frog embryo cells into egg cells. The eggs develop into tadpoles, but then die.

1981

Two scientists report they've cloned mice from mouse embryo cells.

1982

No one can repeat the mouse experiment. The cloned mice turn out to be fake.

1984

A Danish embryologist clones sheep from early-stage embryo cells. Others later repeat his experiment using cattle, pigs, goats, rabbits, and monkeys.

1994

A scientist at the University of Wisconsin clones calves from late-stage embryo cells.

1996

In Scotland, scientist Ian Wilmut puts sheep embryo cells to "sleep" by starving them of nutrients. Then he fuses them with egg cells. The cells begin to divide like new embryo cells.

1997

Wilmut uses the "sleeping cell" baby Dolly from an adult sheep's udder cell. Using an adult cell makes cloning history.

How Cloning Works

The process scientists used to clone Noah is similar to the process used to create Dolly.

1. A female sheep produces an egg. 2. A male sheep releases millions of sperm cells. 3. Inside the female's body, a sperm cell fertilizes the egg. Combined, they provide the genes necessary to create a sheep. 4. The fertilized egg divides, becoming an embryo. A few weeks later, specialized cells form tissues and organs. 5. Five months later, a lamb is born with traits from both parents.

[ILLUSTRATION OMITTED]

Can science bring back the past?

Check out some endangered species that scientists hope to save.

Bactrian deer once ranged through Central Asia, but deforestation decimated their numbers. Now French scientists have pioneered deer embryos in vitro (outside the organism), and hope to rebuild bactrian deer populations using more common deer species as surrogate mothers.

CLONING

1. Scientists remove an udder cell from an adult sheep. 2. They put the cell to "sleep" by depriving it of nutrients. 3. Scientists take an egg cell from another sheep. 4. They remove the egg's nucleus, which houses DNA, or genetic material. 5. The two cells are fused with an electric pulse. Genes in the udder cell enter the egg. Another zap awakens the genes. 6. The fused cells divide and form an embryo. 7. Scientists implant the embryo in the womb of a surrogate mom. The embryo divides and grows normally, with specialized cells forming tissues and organs. 8. Five months later, the cloned lamb is born--a genetic twin to the donor of the udder cell.

[ILLUSTRATIONS OMITTED]

Should Scientist Clone Endangered or Extinct Animals?

YES Supporters say:

* Cloning is the only way to revive extinct species, such as the bucordo, a Spanish mountain goat that died out last year.

* Some endangered animals, like pandas, are almost impossible to breed in captivity. Cloning could produce new animals more quickly.

* Environmental laws protect rare or endangered species from being transported to another country for captive breeding in zoos. The San Diego Zoo in California has collected genetic tissue samples of more than 5,400 species on ice. Cloning such animals could increase the number and diversity of species.

What do you think?

NO Opponents say:

* Extinct animals vanished because they couldn't adapt to survival in the modern world. Their habitats are gone, so they could only survive in zoos.

* Continual habitat destruction threatens most endangered species. Scientists should focus on restoring and preserving natural habitats, rather than cloning animals.

* A wide variety of genes increases the odds that a species will thrive in its environment. A cloned animal's DNA derives from a single animal. In the long run, the lack of genetic diversity may spell trouble for endangered species.

What do you think?

Should Scientists Clone Humans?

POSSIBLE BENEFITS

Supporters say:

* Scientists could clone a person with kidney disease, so the clone could donate a healthy organ to his or her "twin."

* Couples who can't have children could clone themselves rather than adopt a child.

* If a child is killed in an accident, scientists could create a "genetic copy" of the child.

POSSIBLE RISKS

Opponents say:

* Cloning might encourage efforts to create genetically superior human beings.

* Dangerous risks to human health and survival could arise that scientists can't yet predict.

* Cloning a dead child would create a genetic copy but not a duplicate of the person. Personality is the result not merely of genetics but environment as well. If you were cloned, the outcome might be a very different person.

What do you think?

RELATED ARTICLE: Cross-Curricular Connection

Research: Pick an endangered species and research the reasons behind its possible demise. Write a short report on your findings.

[ILLUSTRATION OMITTED]

Did you Know?

* One quarter of all mammals face extinction, including the giant panda, Sumatran tiger, and white rhino. The IUCN-World Conservation Union reported last fall that the number of critically endangered mammals rose from 169 to 180 since 1996; critically endangered primates increased from 13 to 19.

* Until scientist Ian Wilmut cloned Dolly from a sheep's adult udder cell, researchers had only used developing embryo cells in cloning experiments. Scientists may one day be able to clone a human being from a skin cell on your grandmother's arm or from a strand of your hair.

National Science Education Standards

Grades 5-8: reproduction and heredity * diversity and adaptation of organisms * populations, resources, and environments * understanding about science and technology

Grades 9-12: molecular basis of heredity * the cell * understanding about science and technology * science and technology in local, national, trod global challenges

Resources

Noah's New Ark," Time, January 8, 2001, p. 60

"Cloning Noah's Ark," Scientific American, November 2000, online at: www.scientificamerican.com

"Cloning the Endangered," Newsweek, October 16, 2000, p. 56

Directions: Read "Cloning--Hit or Miss?" Then match the word(s) on the left column with the correct phrase on the right.

-- 1. clone                     a. Spanish mountain goat
-- 2. genes                     b. endangered Asian ox
-- 3. embryo                    c. genetically duplicate
-- 4. gaur                      d. early form of a vertebrate animal
-- 5. artificial insemination   e. intestinal infection in livestock
-- 6. sperm                     f. chemical instructions in the
                                   cell nucleus
-- 7. scours                    g. male sex cell
-- 8. bucardo                   h. impregnation without mating

ANSWERS

1. c 2. f 3. d 4. b 5. h 6. g 7. e 8. a