years after the death of Dolly, a female sheep who was the first to
be cloned using an adult somatic cell, four new
sheep have been cloned using Dolly's frozen tissue sample
that has been sitting in a freezer since her death in 2003.
Keith Campbell, one of the original biologists who cloned Dolly, is
keeping the four new quads on his land at the University
of Nottingham as pets. They have been nicknamed "the
Dollies," since they are exact copies of Dolly genetically.
1996, Dolly, who was named after the country singer Dolly Parton, was
cloned at the Roslin Institute near Edinburgh in Scotland. She was
the first mammal to be cloned using an adult cell from a mammary
gland, and was praised as a scientific phenomenon in headlines
worldwide. But as she aged, Dolly experienced several health
complications such as arthritis and advanced lung disease. At the
young age of six, Dolly
was put down because of her poor health.
Dolly lives on. Her leftover sample of tissue has remained in the
freezer all these years later, and now four exact replicas carry her
cloned the Dollies to see if improvements made to the cloning
technique prevented the health problems that Dolly suffered within
the new sheep. So far, Campbell says the Dollies are doing fine and
that they are being watched very closely.
are not doing anything to them," said Campbell. "They have
no health concerns and they show none of the signs of developing the
arthritis that Dolly had."
addition to being healthier than Dolly, the Dollies were also easier
to clone. During Dolly's cloning process, 277 eggs were used to
create 29 embryos and only Dolly survived. With the Dollies, only
five embryos were required to produce each of the four Dollies.
Dollies are already three and a half years old, but Campbell did not
mention their existence until a recent lecture at the European
Parliament debate on cloning and animal welfare. He is
looking to publish further detail on the Dollies in a scientific
journal, noting that the cloning technology is improving but not yet
different groups are taking interest in the Dollies, such as animal
welfare campaigners and stem cell scientists. Animal welfare
campaigners have detailed the suffering that clones and surrogates
experience during the cloning process, and Peter Stevenson of
Compassion in World Farming has even said that "cloning is a
the critics, Campbell insists that improved technology has put the
Dollies at less of a risk of health problems, and that the four sheep
"got the life of Reilly - they potter around and get fed."