Cloning Used in an Effort to Preserve Rare Species
By ANDREW POLLACK
In what could represent a new way to save endangered species, scientists at a Massachusetts biotechnology company said yesterday that they had cloned an endangered Asian gaur and implanted the resulting embryo into a cow in Iowa. The baby gaur, an oxlike creature that is native to India and Southeast Asia, is expected to be born next month.
If the birth of the gaur is successful, it would represent the first cloning of
an endangered species and the first cloned animal to use another species
as a surrogate mother. Scientists say the technique could not only help
preserve endangered species but also even revive species that have
already become extinct.
Indeed, the company, Advanced Cell Technology, of Worcester, Mass.,
said yesterday that it had received permission from the government of
Spain to clone the already extinct bucardo mountain goat, using cells
collected from the last goat before she died earlier this year. The
company is also looking at cloning giant pandas using black bears as
surrogate mothers and frozen cells from Hsing-Hsing and Ling-Ling,
pandas at the National Zoo in Washington that have already died.
But the technique, which seems right out of "Jurassic Park," is raising
ethical questions. Some conservationists fear that cloning would detract
from other, less costly efforts at preserving habitat. And some say it is still
not known whether an animal raised by a mother of a different species
will be able to thrive in the wild.
"It's more like an amusement park version of the species rather than the
wild species," said Kent Redford, director of biodiversity analysis and
coordination at the Wildlife Conservation Society in New York. "We
want to preserve a whole lot more than the genetic material," he added,
saying species should be preserved in their natural environments. "That
can't be reproduced in some Frankenstein lab."
Robert P. Lanza, vice president for medical and scientific development at
Advanced Cell Technology, said cloning would help reverse damage to
wildlife habitat by people. He urged zoos and wildlife officials to begin
collecting and freezing tissue samples of endangered species. "For a few
dollars of electricity you can preserve the genes of all the pandas in
China," he said.
He also said cloning was not likely to work on species that had been
extinct for a long time because it would be difficult or impossible to find
intact DNA. "You're certainly not going to be seeing dinosaurs in your
backyard any time soon," he said.
To create the gaur, scientists took a skin cell from a recently deceased
gaur and fused it with a cow's egg from which the chromosomes,
containing the cow's genetic material, had been removed. The DNA of
the gaur commandeered the egg, which grew into a gaur embryo. The
embryo was implanted in the womb of a cow serving as a surrogate
mother. The baby, which will be named Noah, should be an exact
genetic copy of the gaur from which the skin cell was obtained. The
procedure was reported yesterday in The Washington Post.
Previously, many scientists thought such cross-species cloning would be
impossible because the DNA of the cloned animal would not be able to
interact properly with the rest of the egg cell.
The technique failed many more times than it succeeded. The scientists
created several hundred embryos, but only 81 grew to the stage where
they could be implanted. Some 42 were implanted in 32 cows, but only
eight cows became pregnant. The fetuses were extracted from two cows
for examination, and five cows suffered spontaneous abortions, leaving
only one cow that is still pregnant.
Based on the examination of the fetuses, Dr. Lanza said, the gaurs
seemed to be normal, not crosses between cows and gaurs.
Dr. Lanza said cows were used as egg donors and surrogate mothers
because there are so few gaurs left that it would be unethical to round up
wild female gaurs and subject them to the treatments needed to extract
eggs and implant embryos. And for creatures that are already extinct, he
said, there would be no choice but to use other species as egg donors
and surrogate mothers.
There have been cases of animals of one species being born to surrogate
mothers of another species, such as a house cat giving birth to an African
wildcat. But in these cases the implanted embryos were not the result of
cloning.
Advanced Cell Technology, which is trying to use cloning for medicine
and agriculture, has set up a nonprofit foundation to carry on species
preservation work, since it is not expected to turn into a big business.
The work, assisted by various university scientists, is described in a
paper in the current issue of the journal Cloning and in an article in the
November issue of Scientific American. |
