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If you had asked Thomas Hildebrandt about ten years ago, if the northern white rhino could be saved, his answer would have been dark. Rhino numbers had dropped to a single figure, and the few remaining individuals all had serious reproductive problems. "We thought:" The story is over, "said Dr. Hildebrandt, reproductive biologist at the Leibniz Institute Wildlife Research and the Free University of Berlin. His prognosis became even worse when Sudan, the last male of the subspecies, died in captivity last spring.
On Wednesday, Dr. Hildebrandt and a team of colleagues reported in the journal Nature Communications that the story of the white rhinoceros Using frozen spermatozoa from northern white rhinos and closely related southern white rhino eggs, scientists have created hybrid embryos that can potentially be implanted into mothers carrying southern white rhinos.
Jan Stejskal, Director of International Projects at the Dvur Kralove Zoo in the Czech Republic and author of the article, said that Jan Stejskal is a not very early in achieving the longer-term goal to resurrect a population of northern white rhinos. press conference Tuesday
Several teams around the world are now working together on high tech options to bring back the northern white rhino, which is now functionally extinct. Only two females, a mother-daughter pair named Najin and Fatu, are still alive at Ol Pejeta Conservancy in Kenya
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One of the ways is in vitro fertilization with northern white rhinoceros eggs and sperm. This would involve producing early embryos in Petri dishes which could then be transferred to develop in southern white rhinos, another subspecies
. Hildebrandt and his collaborators began to study this possibility. They had frozen sperm samples from four northern white males, and successfully used a sample to fertilize the eggs of two southern white females, creating a total of four hybrid embryos. In addition, they created three complete embryos of southern white rhinoceros
. The next step is to implant white embryos or hybrids from the south in the coming months, said Cesare Galli, founder and director ] of Avantea, a biotechnology-based breeding company based in Italy , and author of the document.
If this succeeds, the researchers will call on the Kenyan authorities to collect eggs from Najin and Fatu, and to fertilize the eggs of the females. stockpiled white rhino sperm from the north. According to Dr. Hildebrandt, the team hopes to see the first purebred white rhino born to a surrogate mother in three years.
A major disadvantage of this tactic is that the gene pool only includes two northern white cows and four bulls. is extremely limited, and would probably lead to severe consanguinity .
For this reason, the team of Dr. Hildebrandt and a group led by San Diego Zoo Global researchers are also exploring another approach, using what is called induced pluripotent stem cells (also called iPS cells). Such cells have been reprogrammed into blank canvases – they can become any other cell type in the body, including ova and spermatozoa.
The strategy is promising because the researchers have already generated iPS cells (but not yet ova and sperm cells) because the San Diego Zoo has a genetically diverse collection of skin cells from 12 northern white rhinos.
The tradeoff is that iPS cell technology will take longer to develop – maybe a decade, "says Dr. Hildebrandt
Meanwhile, it's important to pursue the possibility of In vitro fertilization with Najin's and Fatu's eggs, he said, especially if potential calves must be bred or socialized
Conservation scientists widely applauded the technical sophistication of the new study, but many expressed concerns about relying too much on high tech solutions. 19659002] There is still "a long way to go to create an embryo and have a viable birth, and then an even longer path to succeed in creating a herd of rhinos", says Susie Ellis Executive Director of the Foundation Rhino.
She fears that technology may be "the brilliant object in the room" that diverts the attention from protecting habitat or supporting crucial conservation efforts on the ground for the remaining rhinos Terri Roth, director of the Cincinnati Zoo's Center for Conservation and Endangered Species Research, said saving the northern white rhinoceros – or any other species – will require many facets.
"We should all work on as many strategies as possible. I said. "Do not throw anyone away, because you can not predict what will happen, we need all possible help."
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