Wildcat Born From House Cat
Scientists have announced an extraordinary birth: They have pulled off the unprecedented feat of transferring a frozen embryo between species by bringing a rare African wildcat to term in the womb of an ordinary house cat.
Researchers at the Audubon Institute Center for Research of Endangered Species said the advancement could be used to resurrect entire species.
"If extinction happens in the wild, the technology will be there to bring the species back," said Ron Foreman, chief executive officer of Audubon Institute.
Rebecca Spindler, a researcher at the National Zoo's Conservation and Research Center in Front Royal, Va., cautioned that the process is no substitute for conservation.
"I think we have to be careful how we use this," Spindler said. "People tend to believe that we can bring a species to the brink of extinction and bring it back. That's not necessarily true."
Still she called Monday's announcement an exciting breakthrough.
The house cat, Cayenne, acts towards her kitten like any typical feline mother: protecting her, nursing her and objecting loudly when her offspring is picked up. And the baby wildcat, named Jazz, nurses off her surrogate mother.
"She thinks she has the ugliest baby in the world, but she takes care of it," said Betty Dresser, the center's director for research.
Jazz was born Nov. 24, about 70 days after scientists had taken sperm from a male African wildcat named Sid and the egg of a female named Sheena and implanted the embryo in the domestic cat.
Because of its size -- ranging in weight from three pounds to eight pounds the African wildcat was considered to be a good match for a domestic cat. Cayenne was chosen because she had proven herself able to carry kittens to term, having had nine litters.
Dresser and C. Earle Pope, another researcher at the center, produced a kitten from in vitro fertilization and a frozen embryo in 1994. In Jazz's case, scientists grew the embryo in an incubator for five days, then froze it for a week at minus 373 degrees. Researchers implanted eight embryos into Cayenne in hopes that at least one would survive.
The freezing process is not a necessary step in embryo transfers, but it was done to advance the idea that extinct species might be recreated years later by thawing frozen embryos when a suitable surrogate species is found.
Scientists are not sure yet how long frozen embryos can be kept, but Dresser said they might be good for hundreds of thousands of years.
"If this technology had been available during the age of the dinosaurs, we might have dinosaurs today," she said.
Before the implant, the frozen embryo was kept with a "frozen zoo" of reproductive material from exotic cats, bongo antelopes and other endangered species in canisters of liquid nitrogen. Those other animals are also the subjects of embryo transfer studies.
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