want to use cloning to save endangered species, but they are having only limited success. A number of times each week, Martha Gómez creates new life. Today, she has set out to produce a South African black-footed cat. Using a razor-thin hollow needle under a microscope, the veterinarian injects a body cell from the endangered species into an enucleated egg cell taken from a house cat. Then she applies an electric current. Scientists like Gómez are hoping for a new era of wildlife conservation. In a bid to save endangered species, they tear down biological barriers and create embryos that contain cell material from two different species of mammals. Iberian lynxes, tigers, Ethiopian wolves and panda bears could all soon be carried to term by related surrogate mothers, and thus saved for future generations.
The world's first surrogate mother of a cloned animal from another species had udders and was named Bessie. In early 2001, the cow delivered a gaur via cesarean section in the United States. The endangered wild ox calf, native to Southeast Asia, had been cloned by the US company Advanced Cell Technology. But the gaur lived only briefly, dying of common dysentery within 48 hours of birth. Since then, researchers have made dozens of attempts at interspecies cloning -- but with limited success. Whenever animals were brought into the world alive, they usually died shortly thereafter.
In 2009, for instance, biotechnicians managed to clone a Pyrenean ibex. The egg was donated by a common domesticated goat. After the birth, the kid desperately gasped for air. Seven minutes later, it was dead.
Many cloning experiments end this way. Geneticists have so far only been able to speculate on the reasons, but the string of failures actually tends to spur researchers to continue. Gómez, for instance, has specialized in cloning wildcats -- and has been quite successful. Cloned African wildcats Ditteaux, Miles and Otis are living in enclosures at the Audubon Center animal facility, and snarl at anyone who approaches them. "They are doing perfectly fine," says Gómez.
Gómez admits that there are problems. Fusing cells from two different species often leads to huge mix-ups. Genes are activated or deactivated at the wrong time, and developmental stages become delayed. In the case of the black-footed cat, for instance, Gómez has so far had no success. "We were able to insert embryos into the uterus of a house cat," she says. "But unfortunately, they didn't develop."
But the researcher remains optimistic. She hopes that she will soon be able to transform body cells from her wildcats into pluripotent stem cells. Cells of this type could considerably simplify the cloning process because they can be used to create any type of body cell and can be easily multiplied. Other researchers have already succeeded in producing such stem cells from snow leopards and northern white rhinoceroses, which are both endangered species.
There are in fact virtually no limits to the creative experimentation of today's biotechnicians. Chinese researchers have fused body cells from panda bears with eggs cells taken from rabbits. But the resulting embryos died shortly thereafter -- in the uteruses of house cats. Meanwhile, Japanese researchers have implanted skin cells from an unborn baby sei whale in enucleated egg cells taken from cattle and pigs.
Other Japanese scientists are even trying to clone the woolly mammoth. Three years ago, cell nuclei from these hairy, tusked ice-age beasts were discovered in mammoth legs that have been frozen in the permafrost of Northeast Siberia for the past 15,000 years.
In the laboratory, a team led by geneticist Akira Iritani injected cell nuclei from the prehistoric animal into enucleated egg cells from mice. The cell constructs only survived for a few hours, but Iritani remains optimistic that an elephant surrogate mother will soon bring to term the first mammoth clone. "From a scientific point of view it is possible," says geneticist Gómez. But is there any point in doing it? The 51-year-old professor hesitates briefly. "I wouldn't do it," she admits. "I would prefer spending all the money on those species that haven't completely vanished from the earth."
Via Dr. Stefan Gruenwald