The clones were then implanted into other subspecies of Spanish ibex or goat-ibex hybrids.
If the environment in which an embryo develops is not a close match, problems can occur during pregnancy. Of the 208 embryos the researchers implanted, only seven goats became pregnant, and just one bucardo made it to term.
The newborn bucardo died of respiratory failure immediately after birth. Dissection revealed the animal had lung abnormalities, although all its other organs looked normal.
Such abnormalities are common in cloning—while a clone's DNA might be identical to its donors', the act of shuffling DNA from one cell to another can lead to irregularities during development.
A Step Forward
Smithsonian's Wildt called the work a "highly noteworthy scientific accomplishment."
"Offspring was produced from an animal well known to have suffered a recent extinction."
The bucardo story "is fascinating, because resurrection-by-cloning was the only option," Wildt said.
But there are "vastly more effective and logical approaches" at conserving virtually all living wildlife species, he added, including re-establishing wild habitats, captive breeding by natural means, and artificial insemination.
"The strong recovery of the black-footed ferret and giant panda are two excellent examples" of species that have come back from the brink thanks to conservation efforts, Wildt said.
(Related: "Ferrets Slinking Back From Brink of Extinction in U.S." [August 9, 2007].)
Reproductive biologist Bill Holt at the Zoological Society of London, who did not participate in this study, added that generating just one or a few animals via cloning "will not necessarily produce a viable population that would survive into the future."
Even if all resulting offspring were healthy, he said, the fact that they only have a few genetic samples of the bucardo to work with would mean there would be no genetic diversity in the population, as in inbred groups.
"They would be very susceptible to disease or even climatic change and may not be able to survive for very long."
|
SOURCES AND RELATED WEB SITES
|
