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Battling extinction with test-tube tigers.

Battling extinction with test-tube tigers

A surrogate mother named Nicole has provided scientists with a moment to remember. The 9 1/2-year-old Siberian tigress gave birth on April 27 to three Bengal tiger cubs, the world's first "big cats" produced through in vitro fertilization and embryo transfer. The births have boosted biologists' hopes for preventing extinction of the world's five tiger subspecies as well as a number of other endangered animals.

Veterinarians at the Henry Doorly Zoo in Omaha, Neb., delivered the cubs through Cesarean section. Two cubs later died, one from respiratory complications and the other from kidney failure. Zoo scientists do not think the deaths were related to the fertilization/implantation technique.

Reproductive physiologists Ann Miller and Leslie Johnston of the National Zoo in Washington, D.C., tailored the technique to tigers in collaboration with researchers from the Henry Doorly Zoo and the Minnesota Zoological Gardens in Minneapolis. They also developed a miniaturized in vitro fertilization lab for use in Omaha and possibly in the wild.

The team gave Bengal tigresses hormones that increase egg production, then removed the eggs for fertilization in a petri dish. The resulting embryos were placed in Nicole's reproductive tract.

Only 3,000 to 5,000 tigers remain in the wild, most driven into isolated reserves by human encroachment, notes tiger specialist Ulysses Seal of Minneapolis, a consultant on the project. This fragmentation has separated potential mates and increased the chances of inbreeding, he says.

"One of our objectives in the long term will be to move genetic material from one reserve to another," Seal told SCIENCE NEWS. "Moving embryos rather than animals is much less dangerous for the animals." In vitro fertilization not only promises to bolster genetic stocks in zoos and reserves, but also might enable biologists to freeze embryos of species on the verge of extinction, he adds.
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Author:Stolzenburg, William
Publication:Science News
Date:May 26, 1990
Words:308
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