CLONING
Dolly,
the name of an ordinary looking sheep made front pages
around the world in 1997: Dolly, unlike any other
mammal that has ever lived, is an identical copy of
another adult and has no father. She is a clone, the
creation of a group of veterinary researchers. That
work, performed by Ian Wilmut and colleagues at the
Roslin Institute in Edinburgh, Scotland, has provided
an important new research tool and has shattered a
belief widespread among biologists that cells from
adult mammals cannot be persuaded to regenerate a
whole animal.
Wilmut
and his co-workers accomplished their feat by transferring
the nuclei from various types of sheep cells into
unfertilized sheep eggs from which the natural nuclei
had been removed by microsurgery. Once the transfer
was complete, the recipient eggs contained a complete
set of genes, just as they would if they had been
fertilized by sperm. The eggs were then cultured for
a period before being implanted into sheep that carried
them to term, one of which culminated in a successful
birth. The resulting lamb was, as expected, an exact
genetic copy, or clone, of the sheep that provided
the transferred nucleus, not of those that provided
the egg
This
startling breakthrough opens vast scientific possibilities
but at the same time also raises many potential issues
which will be discussed in the section: "Issues".
The most controversial issue is perhaps about human
cloning. Is it possible?
"Researchers
. . . hope that one day, the ability to clone adult
human cells will make it possible to 'grow' new hearts
and livers and nerve cells . . . As for infertile
couples, 'We are interested in giving people the gift
of life'. . . "
Technically,
it is already possible to make a human clone. But
clones do not have the exact genetic material of their
donor, because a key bit of DNA actually lives outside
the cell nucleus, and is not removed when the cloning
procedure takes place. This is the mitochondrial DNA
which is passed down by the mother.
So unless a woman uses her own eggs to clone herself,
the clone will not be a 100-per-cent replica of the
original. Of course, environment also plays a key
role in how people turn out, and while the nature-nurture
debate continues, we will not be able to say for certain
how great each role is.
However, a group of doctors plans to clone the first
human being in two years' time, in a bid to help infertile
couples have babies. Companies are already gearing
up for the potential boom in demand by storing human
cells for future cloning. But many people are against
the very idea of human cloning, which has been condemned
by moral, scientific and religious authorities.
