Biodiversity
Scientists have taken another step to save the theoretically extinct northern white rhino. And they did this with the help of a southern white rhino from Pairi Daiza zoo.
Thursday January 25, 2024 at 1:11 PM
There are only two northern white rhinos left, two females: Najin and her daughter Fatu. Since they cannot reproduce, the species is extinct. In theory anyway. Scientists worldwide are working on ways to revive the species. The BioRescue Project is a consortium of scientists trying to save the species using in vitro fertilization methods. Such techniques are new in rhinos.
“The technique of embryo transfer is well established for people and animals such as horses and cows,” says project leader Thomas Hildebrandt. “But for rhinos it is completely unknown territory. Everything had to be invented, developed, tested and proven to be safe to use. Together with the team and professional partners, I developed the devices to insert a tiny embryo into a two-ton animal.”
Infection
It took thirteen attempts to achieve such an IVF pregnancy in rhinos. First there were tests with southern rhinos, of which thousands are still alive. Sperm from a southern white rhino from an Austrian zoo served to fertilize the eggs of Ellie, a southern rhino from Pairi Daiza. The embryos were then created in a lab in Italy. Two of those embryos were implanted in the southern white rhino Curra in the Ol Pejeta Nature Reserve in Kenya.
And Curra turned out to be pregnant, but later things went wrong. Seventy days after implantation, the rhino died from an infection with clostridia, a deadly bacterium. An autopsy has now shown that the IVF fertilization was a success. A male calf measuring 6.5 centimeters was found. The development looked good and, according to the scientists, the animal had a 95 percent chance of being born alive.
“It took many years to achieve this and we are happy that we have proof that the technology works,” says Hildebrandt. “It is bitter that this step has been confirmed under such tragic circumstances, with the death of surrogate mother Curra and her unborn calf, but I am confident that this is a turning point for the survival of the northern white rhino and the health of the ecosystems of Central Africa.”
Surrogate mother
The next step is to apply the technique to the embryos of northern white rhinos. There are about thirty of these embryos that were made with eggs from Fatu and two deceased male white northern rhinos. These embryos are stored in liquid nitrogen at minus 196 degrees Celsius.
But to achieve such a pregnancy in a northern white rhino, scientists must experiment again. Fatu and her mother Najin are unable to get pregnant due to their age and health problems. And so a surrogate will be sought. A southern white rhino will therefore have to carry the embryo of two northern white rhinos. IVF treatment across two subspecies has never been tried before, but the team is confident it will work. That step could become a reality in about two to three years.
