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A 28-year-old rhinoceros named Najin and his daughter, Fatu, are the only white rhinos in the north of the planet. They live at Ol Pejeta Conservancy in Kenya under constant armed guard. Both animals are infertile. In March, veterinarians euthanized Sudan, Najin's father, and the last male rhinoceros of their species. Once Najin and Fatu die, their subspecies goes the same way.
But the genes of the northern white rhinos could survive. In a new study published Wednesday in Nature Communications, scientists used in vitro fertilization to create viable rhinoceros embryos.
An international team of zoologists, veterinarians, and other researchers collected unfertilized eggs from southern white rhinos, a closely related subspecies with a population of about 20,000 individuals. In one dish, scientists used northern white rhinoceros sperm to fertilize southern white rhino eggs, producing hybrid embryos.
Two hybrid embryos were frozen for future implantation, the researchers said. They anticipate, after developing the proper technique, that it will be possible to transfer embryos to female southern white rhinos in the years to come. A hybrid calf provides some genetic continuity for the northern white rhinoceros even after extinction.
"It is a very ambitious and very courageous last resort effort to save some of the genetics of a spectacular animal," said biologist Duke University, who is studying extinctions and has not been involved in this project.
Northern white rhinos are not evolutionary failures. Rhinos have failed, as Thomas B. Hildebrandt, biologist and author of the study, said Tuesday, because their skins were not bullet-proofed. They have failed because rhinoceros horns, the gram for the gram, are worth more than gold – seeking high prices as status symbols or for their medicinal powders. (The horns, mainly composed of a protein called keratin, are as medically useful as nails.)
Hildebrandt, professor at the Leibniz Institute for Zoological and Wildlife Research in Berlin, and his colleagues do part of a project that has stored genetic material of the northern white rhinoceros for decades. Oliver Ryder, a conservation geneticist at the San Diego Zoo, took skin samples from Sudan in 1986 as part of a rhinoceros cell bank. According to Hildebrandt, scientists started freezing white rhino sperm in 2008, which is about 300 milliliters, about the size of a soda can
but semen collection is relatively easy. A wild animal of two tons.
"It's a technological feat," said David E. Wildt, senior researcher at the Smithsonian Conservation Biology Institute, who was not involved in this research. The study's authors used a 60-inch (patent-pending) instrument to insert a needle through the anus of the South-anesthetized white rhinos and into the ovarian tissue. An ultrasound monitor provided the only orientation for egg collectors.
Embryos are viable and "beautiful," said Wildt. He added: "It's the first step of a long journey to produce live offspring."
Veterinarians have successfully used in vitro fertilization in horses, cattle, and other animals, but never as fat as a white rhino. are the only way to save the northern white rhinoceros genes, said biologist Terri Roth, director of the Center for Conservation and Threatened Wildlife Research at the Cincinnati Zoo. These genes could benefit white rhinos that move in their parents' old habitats, or confer benefits to live rhinoceroses during epidemics.
Chances are against a complete revival of white rhino, according to Roth, who oversaw the first successful reproduction of a captive Sumatran rhinoceros in 2001. "Even though the moon and the stars were all aligned "And that a rhinoceros surrogate gave birth to a hybrid calf," that still has not brought back the subspecies ".
Ryder from the San Diego Zoo, along with Hildebrandt and other reproductive biologists, developed a plan in Vienna in 2015 to save the subspecies. It will be possible to bring back a complete Northern White Rhinoceros, predicts Ryder, which would require an egg and sperm.
Hildebrandt and his colleagues plan to harvest eggs from Najin and Fatu, and the researchers are "extremely confident" that they would succeed. The highest risk is not lacking in acquiring eggs, says Hildebrandt, but to adult rhinos. The animals must be anesthetized for two hours, "which is a pretty risky situation."
One of Hildebrandt's co-authors is Katsuhiko Hayashi of Kyushu University, a pioneering reproductive biologist who turned mouse cells into eggs. The team aims to replicate this success with rhinoceros stem cells. So far, they have generated 12 lines of rhinoceros stem cells, said Hildebrandt.
All scientists who spoke with The WashingtonPost agreed that biological techniques can complement the protection of rhinoceroses on the ground. Funds allocated for laboratory research generally do not come from the same sources as funds for other conservation purposes. "We should come to that with everything we have," Roth said.
"It's a big puzzle, there's not one element that's going to be the answer," said Susie Ellis, executive director of International Rhino. Foundation. "No species has ever been saved by the high tech approach alone." Science is "very important," but it must be paired with "working with local communities and politicians."
Pimm, as excited as he was about this result, offered a warning . We can not afford to adopt a cavalier attitude towards extinction, as if animals were something to bring back as we pleased, he said. "The main event must be: We must stop poaching rhinos."
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