CLONED LAMB REVIVES ISSUE: HUMANS NEXT?

Byline: Gina Kolata The New York Times

When a scientist whose goal is to turn animals into drug factories announced Saturday in Britain that his team had cloned a sheep, the last practical barrier in reproductive technology was breached sooner than most scientists anticipated, experts say.

Now these experts say the public must come to grips with issues as grand as the possibility of making genetic copies of humans and as mundane, but important, as what will happen to the genetic diversity of livestock if breeders start to clone animals.

Ursula Goodenough, a cell biologist at Washington University in St. Louis, joked that with human reproduction by cloning, ``There'd be no need for men.''

On a more serious note, Stanley Hauerwas, a divinity professor at Duke University, said he fears ``a kind of drive behind this for us to be our own creators,'' although proponents of cloning ``are going to sell it with wonderful benefits'' for medicine and animal husbandry.

Kevin FitzGerald, a Jesuit priest and a geneticist at Loyola University in Maywood, Ill., cautioned that people might not understand clones. While a clone would be an identical but much younger twin of the adult, people are more than just the sum of their genes, he said.

A clone of a human being would have a different environment than did, at the same age, the person whose DNA was used. With years of difference in birth time, the adult and clone would have much more difference in their environments than identical twins born moments apart.

The clone would be a different person from the adult whose DNA was used. The clone would even have to have a different soul, FitzGerald said.

The sheep cloning was done by Ian Wilmut, a 52-year-old embryologist at the Roslin Institute in Edinburgh. Wilmut announced that he had replaced the genetic material of a sheep's egg with the DNA from an adult sheep and created a lamb that is a clone of the adult. His results will be published in the British journal Nature on Thursday.

DNA from adult animal

While other researchers had previously produced genetically identical animals by dividing embryos soon after they had been formed by eggs and sperm, Wilmut is believed to be the first to have created a clone using DNA from an adult animal. Until now, scientists believed that once adult cells differentiate - to become skin cells or eye cells, for example - their DNA would no longer be usable to form a complete organism.

Wilmut reported that, as a source of genetic material, he had used udder or mammary cells from a 6-year-old adult sheep. The cells were put into tissue culture and manipulated to make their DNA become quiescent. Then Wilmut removed the nucleus, containing the genes, from an egg cell taken from another ewe. He fused that egg cell with one of the adult udder cells.

When the two cells merged, the genetic material from the adult took up residence in the egg and directed it to grow and divide. Wilmut implanted the developing embryo in a third sheep that gave birth to a lamb which is a clone of the adult that provided the DNA. The lamb, named Dolly, was born in July and seems normal and healthy, Wilmut said.

Could clone people

In an interview, Wilmut said he wanted to create new animals that could be used for medical research, and he dismissed the notion of cloning humans.

``There is no reason in principle why you couldn't do it,'' he said. But he added: ``All of us would find that offensive.''

Yet others said that might be too glib. ``It is so typical for scientists to say they are not thinking about the implications of their work,'' said Lee Silver, a biology professor at Princeton University.

Few experts think that sheep or other farm animals will be the only animals to be cloned. While cloning people is illegal in Britain and several other countries, there are no laws against it in the United States, according to John Robertson, a law professor at the University of Texas at Austin who studies bioethics.

Even if such laws were adopted in the United States, Silver said doctors could set up clinics elsewhere to offer cloning. ``There's no way to stop it,'' Silver said. ``Borders don't matter.''

Ronald Munson, an ethicist at the University of Missouri at St. Louis, said equipment needed for cloning is basically simple.

``This technology is not, in principle, policeable,'' he said. ``It doesn't require the sort of vast machines that you need for atom-smashing. These are relatively standard labs. That's the amazing thing about all this biotechnology. It's fundamentally quite simple.''

Customized genes

One immediate implication of cloning, Silver said, would be for genetic engineering: custom-tailoring genes. Scientists are now unable to take a gene and simply add it to cells. The process of adding genes is so inefficient that researchers typically have to add genes to a million cells to find one that takes them up and uses them properly. That makes it very difficult to add genes to correct a genetic disease or genetically enhance a person, Silver said. But now, ``it all becomes feasible,'' he said.

After adding genes to cells in the laboratory, scientists could fish out the one cell in a million with the right changes and use it to clone an animal - or a person. ``All of a sudden, genetic engineering is much, much easier,'' Silver said.

Wilmut is hoping that the genes for pharmacologically useful proteins could be added to sheep mammary cells and that the best cells could be used for cloning. The adult cloned ewes would produce the proteins in their milk, where they could be easily harvested.

Because mammal cloning had been considered so far-fetched, scientists had discouraged ethicists from dwelling on its implications, said Daniel Callahan, a founder of the Hastings Center, one of the first ethics centers.

In the early 1970s, ``there was an enormous amount of discussion about cloning,'' Callahan said. Ethicists mulled over the frightening implications. But scientists dismissed these discussions as idle speculation, Callahan recalled, and urged ethicists not to dwell on the topic.

``A lot of scientists got upset,'' Callahan said. ``They said that this is exactly the sort of thing that brings science into bad repute, and you people should stop talking about it.''

Cloning captured the popular imagination in the 1970s. In his 1970 book, ``Future Shock,'' Alvin Toffler speculated that ``cloning would make it possible for people to see themselves anew, to fill the world with twins of themselves.''

CAPTION(S):

Photo

PHOTO (color) Dolly, a lamb born seven months ago in Scotland, is the world's first clone of an adult mammal.

Associated Press