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FEBRUARY 24, 1997TRANSCRIPT |
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Scientists have cloned an adult mammal for the first time, producing a lamb named Dolly. The lamb was cloned from a 6-year-old ewe, using tissue taken from the ewe's udder. The study, to be released in this week's Nature, has raised questions over the possible uses, and ethical dilemmas, of this development. Following a background report and discussion of the science of today's announcement, Jim Lehrer leads a discussion of the ethics of cloning.
NEWSHOUR LINKS:
A RealAudio version of of this segment is available.
February 24, 1997:
A background report on the cloning of sheep in Scotland.
February 24, 1997:
A discussion on the ethics of genetic engineering.
April 3, 1996:
Fred De Sam Lazaro reports on scientific advances in genetic research and the ethical questions they raise.
EXTERNAL LINKS:
The Genetics and Public Issues Program at The National Center for Genome Resources (NCGR) discusses cloning.
Discussion of Ethics and Social Issues in Gene Research at the Human Genome Project.
ELIZABETH FARNSWORTH: Seven-month-old Dolly is an ordinary-looking sheep who came into the world in an extraordinary way. She is a scientific first -- a clone -- meaning she's an exact copy of another sheep. Dolly's birth last summer was the end result of 23 years of work by Dr. Ian Wilmut of the Roslin Institute just outside Edinburgh, Scotland.
IAN WILMUT, Embryologist: Dolly was born last July, and she's a perfectly healthy animal. And next autumn, come the beginning of the next breeding season, she'll be given the chance to breed and to continue with her normal life.
ELIZABETH FARNSWORTH: Here's how Dolly came to be. Dr. Wilmut and his colleagues removed cells from the udders of a female sheep, put them in test tubes, and made them inactive or dormant. Then they removed DNA or genetic material from the unfertilized eggs of other female sheep.
They inserted the DNA from the udder cells into the eggs and then exposed them to an electric current, fusing them together into one cell which could develop into an embryo.
The resulting embryos were then implanted into 13 surrogate mother sheep. Only one became pregnant, and she delivered Dolly, who was named, by the way, for country western singer Dolly Parton.
Cloning has long been a staple of science fiction. The dinosaurs in Jurassic Park were cloned from bits of DNA kept alive in tree sap, and in Brave New World, Aldous Huxley wrote about the production of humans and animals. And American researchers created copies of human embryos in 1993.
But those embryos were not viable, and most scientists thought copying an animal was impossible until Dolly was born.
Some scientists envision great benefits from cloning.
They say animals could be created to produce proteins some humans lack, like the clotting factor in human blood. Cloned animals could also produce human medicines in their milk. But Wilmut drew the line at cloning humans.
IAN WILMUT: We think it's important to prohibit the misuses. We would share the concerns that this technique should not be used in human beings but also to make sure that we are able to use it for the purposes where there is a benefit.
If the company with whom we collaborate, PPL Therapeutics, can use this to bring forward more quickly health care products for treatment of diseases like hemophilia, the blood clotting factors or the protein anti-tripsin to treat emphysema and cystic fibrosis. We think that these are important benefits which shouldn't be lost.
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