Government researchers are counting on Dolly to reverse a
decade of genetic engineering setbacks that yielded diabetic sheep,
arthritic pigs and none of the "super animals" they were trying to
Scottish researcher Ian Wilmut, who cloned Dolly from the cells
of an adult sheep, is scheduled to visit the Agriculture Research
Service in Beltsville on Wednesday to talk about his methods.
Soon, U.S. government scientists hope to deploy the cloning
methods that Wilmut used to shock the world.
Caird E. Rexroad Jr, research supervisor at the Agriculture
Department's Gene Evaluation and Mapping Lab at Beltsville, said
researchers hope to begin their own experiments within months. He
said in an interview last week: "This is wonderful for us. We
needed the stimulation from this as well as the opportunities it
The Beltsville scientists intend to use Wilmut's method but in
a different way. Rather than using adult cells,a the U.S.
scientists plan to use fetal cells for cloning. And instead of
sheep, the scientists at Beltsville are hoping to use Wilmut's
methods on cattle.
But they want to use cloning to study genes for the purpose of
producing bigger, leaner and faster-growing farm animals that need
less food and produce less waste.ts
Rather than cloning - creating a new animal from a single cell
of an existing animal - researchers at Beltsville have been using a
related genetic engineering method of transferring genes from other
animals. And humans.
In long-running experimentation that began in the mid-1980s,
the Agriculture Department researchers transferred genes that
control growth from humans and other mammals into farm animals.
These genes - obtained by cloning - were injected into fertilized
eggs that were implanted into farm animals in Beltsville.
Part of the experiment was successful: The genetic makeup of
the pigs, sheep and other animals was changed, and the animals
passed along the changes to their offspring. As a result of the new
gene, many of the transgenic animals, as they are called, produced
the growth hormone from their pituitary glands.
But the problem that the government scientists have not been
able to overcome is controlling the growth hormone produced by the
experimental animals. The hormone caused diabetes and other ill
effects in sheep. While some of the pigs were better muscled, many
of them had health problems such as arthritis, pneumonia and
lethargy that prevented breeding.
"If you can't avoid the health problems, you can't go on," said
Vernon G. Pursel, swine researcher at the Beltsville labs,
explaining why he stopped most of that research several years ago.
In his latest experiments, Pursel has been producing pigs
implanted with genetic material called IGF1 (Insulin-like Growth
Factor) in an effor t to avoid the unpredictable effects of growth