Test-tube rhino to bring back subspecies from extinction
Scientists create breakthrough hybrid embryos in bid to save northern white rhino
When the last male northern white rhinoceros, 45-year-old Sudan, died in March it looked like the end of the sub-species was nigh. With only two females alive, and no breeding partners left, the rhino was functionally extinct, and just a few years away from dying out entirely.
But in a world first, scientists have created a test-tube rhino embryo from the frozen sperm of a northern white male and the egg from a southern white female. Now they know that IVF is possible for rhinos, they plan to take eggs from the last surviving northern white females and artificially inseminate them with the frozen sperm before implanting them into southern white rhino females to act as a surrogate.
The team is confident that the first northern white rhino calves will be born within the next three years, bringing the subspecies back from the brink of extinction.
“These are the first in vitro-produced rhinoceros embryos ever,” said Professor Thomas Hildebrandt, head of the department of reproduction management at the Leibniz Institute for Zoo and Wildlife Research in Berlin.
“They have a very high chance to establish a pregnancy once implanted into a surrogate mother. We will start with implanting a hybrid embryo in the next few weeks and months to test the system. And after that the success we will plant a white rhino into a surrogate mother.
“We hope within three years we will have the first northern white rhino calf born.”
Northern white rhinos are the most endangered mammal on Earth and all conservation efforts to save them have been thwarted by poaching, civil war and habitat loss. Since the 1960s the population has fallen from 2,000 individuals to just two remaining females today, mother and daughter Najin and Fatu, who are protected at the Ol Pejeta Conservancy near Mount Kenya.
The task of taking eggs from a rhino has not been attempted before, and scientists were forced to invent a special 1.8m device to stimulate the female’s ovaries and collect the oocytes. The eggs were harvested from 20 females from zoos across Europe and the shipped to the Avantea medical laboratory in Italy for insemination with frozen sperm, which was collected from the last four northern white rhinos.
“In our lab we were able to develop procedures to mature the oocytes, fertilise them by intracytoplasmic sperm injection (ICSI) and culture them,” said Professor Cesare Galli of Avantea.
“For the first time we had rhino blastocysts – an early stage of an embryo – developed in vitro, similarly to what we do routinely for cattle and horses.
“The successful development of a hybrid embryo is a major step towards the first birth of a northern white rhino through artificial reproduction techniques.”
The team is now waiting for permits from Kenya to take eggs from Najin and Fatu, but are hoping to get started within the next few months. In the meantime they are working on perfecting the embryo transfer procedure and plan to implant the hybrid embryos into southern white rhinos later this year.
Rhinos have a 16-month gestation period so the first calves with northern white rhino DNA could be born by 2020. The scientists are also trying to create rhino sperm and eggs directly from stem cells.
Because there are only two females left and all the available semen comes from only four males, IVF alone would not be able to create a self-sustaining population of northern white rhinos with the necessary genetic diversity. Instead, the team has found skin samples from ear notches taken from 12 rhinos before they died, from which they hope to create eggs and sperm.
The scientists say the work creates a blueprint for how to save endangered species, and even those that have already gone extinct.
Once they have a viable population, the rhinos will be taken back to central Africa.
“This research is groundbreaking,” said Steven Seet, of the Leibniz Institute for Zoo and Wildlife Research. “We are witnessing the development of a method that can help to compensate the negative impact of humans on nature.”
The breakthrough was praised by conservationists, but they said more needed to be done to protect endangered habitats.
WWF chief adviser on wildlife Cath Lawson said: “Tragically, we lost the fight to save the northern white rhino in its natural habitat over a decade ago. There is still time to save the remaining five species of rhino, but innovative reproductive techniques are of limited value unless there are safe places for them to thrive.
“That means protecting landscapes in Africa and Asia where they live and cracking down on poaching and the devastating illegal trade in rhino horns.”
The research was published in the journal Nature.
– © The Daily Telegraph
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