Cloned Sheep Dolly
In Brief
Died after Six
Years
• Dolly’s premature death is a solemn reminder that cloning is a complex process, still
not yet fully understood by cloning researchers.
• Scientists should investigate subtleties and monitor cloned animals’ lives until death,
so as to properly understand the scope and consequences of any inherent problems.
• Other cloned animals after Dolly include: Cumulina the cloned mouse (named for the
“cumulus cell” from which she was made), followed by cloned cows, goats, pigs,
rabbits, and one small kitten called Carbon Copy.
The world of cloning has been dealt a major setback
with the recent announcement of Dolly’s death. The
world-famous sheep cloned was put to sleep after a
veterinary examination confirmed that she was suffering
from a progressive lung infection.
(2)
Mutations of gene and protein structure and
function, resulting in abnormal embryo growth.
(3)
Cloned and in vitro embryos have different needs.
(4)
Unnatural origin of a clone’s genetic material.
In 1996, Dolly first made the headlines by being
the world’s first successful cloned mammal. Scientists
from the Roslin Institute in Scotland had created Dolly
from a seemingly simple two-step procedure: (1)
Penetrate into the egg, remove its genetic material, then
replace it with DNA from a body cell, such as a skin or
mammary cell. (2) With electrical or chemical triggers,
stimulate the egg to start dividing like a normal fertilized
egg. This cloning experiment once hailed as a
revolutionary breakthrough in science is now serving
as a solemn reminder to researchers of the dangers of
“playing God”.
In Dolly’s case, one of the biggest fears was that
she was cloned from the breast cell of a six-year-old
adult ewe, and thus might have been born prematurely
old. In 1999, scientists discovered that some of the cells
in her body had started to show signs of aging; and in
2002, Dolly’s creators found that she had developed
arthritis at the relatively early age of five and a half years.
(A sheep of her breed usually lives up to 12 years.)
Cloning is still very much a field in its teething
stages — with far more recorded failures than successes.
After all, it did take 277 failed attempts before Dolly
was created.
The merino ewe Matilda was created by technology
similar to that which produced Dolly. However, Mr Rob
Lewis (executive director of the South Australian
Research and Development Institute), did not think that
Matilda’s demise was caused by premature aging as in
Dolly’s case.
In animal experiments, only a mere one percent of
cloned embryos survive to birth. Of those that survive,
most suffer from health problems such as heart, lung
and weight abnormalities.
There are many theories as to why clones fail:
(1)
Initial physical damage to the nucleus or the cell’s
other viscous organelles, which contain all the
essential chemicals for normal development.
In other related news, Australia’s first cloned sheep
has also mysteriously died despite being in apparent
good health. An autopsy failed to find any reason for its
death.
Researchers say it will take years, probably even
decades before science comprehends the intricacies of
the highly complex process of cloning. Before then,
mankind would be foolish to embark on any attempts
to clone humans without running the risk of introducing
subtle genetic errors that could create deformed and
diseased children.
APBN • Vol. 7 • No. 6 • 2003
247
www.asiabiotech.com
248
APBN • Vol. 7 • No. 6 • 2003
APBN • Vol. 7 • No. 6 • 2003
249
www.asiabiotech.com
250
APBN • Vol. 7 • No. 6 • 2003
APBN • Vol. 7 • No. 6 • 2003
251