by
Susan V. Seligson
To the
swelling chorus of people who oppose mammalian cloning, scientists
like James Robl have already gone too far. Never mind the audacity
of churning out genetically indistinguishable rabbits and cows.
If Robl and his colleagues in the Universitys Department of
Veterinary and Animal Sciences can incorporate human DNA into the
egg cells of cows, whats to stop them from riding the slippery
slope to a world menaced by human-bovine monsters or a soulless
society that clones babies for racial purity, cannon fodder or spare
parts?
Moral
and scientific integrity, for starters. In the company of the modest,
sedately focused Robl, these alarmist cries seem misplaced, even
hysterical. Not only, as Oprah might say, do these researchers have
no intention of going there, but such diabolical notions
remain as scientifically fanciful as his daughter Leahs half-pig
half-cow chimera portraits which adorn the walls of Robls
Paige Laboratory office. And when Robl speaks of his work, it is
with nothing less than reverence for the mysteries of life that
evade even the biologist as he literally cuts, splices and otherwise
tampers with the genetic material essential for life to exist.
Sometimes
I think the question isnt, why dont we succeed more
often, says Robl, describing the delicate but relatively crude
process of poking a host cell membrane until it annexes the chromosome-packed
nucleus of a donor cell, but why we succeed at all.
A kind of miracle happens, even in the laboratory.
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"Sometimes
I think the question isnt, why dont we succeed more
often, but
why we succeed at all.
- Professor Robl of Vet & Animal Sciences
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Thanks to memorable scenarios
about pod people, the petri-dish rebirths of Hitler or velociraptors,
and Woody Allens slapstick efforts to clone Sleepers
Fearless Leader from his steamroller-flattened nose, the word cloning
hits a familiar, often raw nerve. Once again scientists are accused
of playing God. Like Darwins theory of evolution
or early in-vitro fertilization, cloning has pitted science against
theology. Professional glory and potential corporate gain are cited
as threats to traditional individual rights. (See sidebar, page
11.) But, like cases of summarily banned books their detractors
dont even bother to read, the uproar over cloning obscures
the fact that few lay people have a clear understanding of what
cloning is. Despite the noisy 1997 debut of Dolly the sheep, most
people would be startled to know that cloning dates back to the
sixties, when an adult frog was copied by replacing
the DNA of a frog embryo. And most are unaware that without genetic
engineering, the cloning process would be of little clinical or
commercial value.
At
its most basic, cloning means copying, which is why critics view
laboratories like Robls as ghoulish assembly lines. A clone
from the Greek klwn, meaning twig is the offspring
derived from a single ancestor, either an organism or a cell,
with genes identical to that ancestor or that cell. Robls
cows are clones as the result of the delicate substitution of
one nucleus for another, but some tumors are also clones, as are
animals like corals, which reproduce without sex. Were cloning
every time we cultivate a house plant with a cutting. Identical
twins are clones, as well as being comforting reminders of the
role external factors play in shaping what makes each of us unique.
Even if it were possible to clone adult humans (no one knows for
sure), a copy of Hitler could turn out to be an ordinary
Joe, making a living selling his inferior oil paintings.
Cloning
a mammal, any mammal, is a huge leap from cloning a chrysanthemum.
The illustrious Dolly emerged after about 300 attempts, and Robl
himself has been working with mammalian cloning for the last 15
years. No ones had much success cloning mice, Robls
first foray into the field. Robl and his associates cloned their
first cow after 12 years of trying. Because cloning eliminates
the role of sperm, the researchers had to start from scratch with
freshly ovulated eggs. We had to look at what mediates the
eggs response to the sperm, and figure out what the optimum
stage is to replace the eggs genetic material with the donor
material, Robl explains. Talk about microsurgery. Robl reaches
for a series of micrographs showing the donor nucleus, packed
with chromosomes, being poked close to the egg cell membrane,
then pinched like a pulling a marble out from inside a balloon,
says Robl. After years of manipulating these cells and nuclei
Robl says he can feel what needs to be done almost as if he were
working with his actual fingers. A high voltage electrical shock
is used to stimulate the nucleus to melt into the
cytoplasm of the recipient egg after a few minutes, and another
pulse activates the start of cell division. Various experiments
over the years resulted in about 20 genetically identical rabbits,
nice normal bunnies which department people adopted
as pets, says Robl.
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