A house cat gave birth to a rare African wildcat after scientists pulled off what they called the unprecedented feat of transferring a frozen embryo between species.
Researchers at the Audubon Institute Center for Research of Endangered Species said the advancement could bolster endangered species or even 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 of the Audubon Institute.
The house cat, Cayenne, treats her kitten, Jazz, like any feline mother would. She protects her, nurses her and objects loudly when her offspring is picked up.
"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.
The African wildcat was considered a good match for a domestic cat because of its size, which ranges from three to eight pounds. Cayenne was chosen because she could carry kittens to term, having borne 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 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 in canisters of liquid nitrogen with a "frozen zoo" of reproductive material from exotic cats, bongo antelopes and other endangered species. Those animals are also the subjects of embryo transfer studies.
Rebecca Spindler, a researcher at the National Zoo's Conservation and Research Center in Front Royal, Va., called the birth "an exciting breakthrough," but warned that it would not be a full substitute for conservation of rare species.
"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."