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“There are only 2 northern white rhinos remaining on the earth”, this topic has recently appeared in hot searches. In fact, as early as 2018, when the last male northern white rhinoceros Sudan (Sudan) passed away, there were only 2 northern white rhinoceros left on the earth. White rhinoceros.
The 32-year-old Najin(Najin) and her 21-year-old daughter Fatu(Fatu) is the only two northern white rhinoceros remaining. They are all females and can no longer breed naturally. If modern technology cannot help them produce offspring, then we can only watch the northern white rhinoceros go extinct.
Now, the northern white rhinoceros is standing on the edge of a completely extinct cliff, waiting for the answer from modern technology.
In Sudan in 2010, there were 8 northern white rhinoceros on the earth at that time| Lengai101 / Wikimedia Commons
They arePush to the cliff
The Northern White Rhinoceros once had a relatively safe situation. 60 years ago, there were more than 2,000 northern white rhinos in Africa; however, due to wild poaching, by 1984, this number dropped to about 15.
As a land animal whose size is second only to elephants, rhinos have almost no natural enemies in the wild. Of these giant beasts that were once widely distributed on the earth, there are now only five species left: Sumatran rhino, black rhino, Java rhino, Indian rhino and white rhino-the first three have been listed as critically endangered species. From a numerical point of view, the white rhino is not endangered, because in addition to the remaining two northern white rhinos, another subspecies of white rhinos, southern white rhinos, has about 20,000.
Southern white rhinoceros in a relatively safe situation|Zigomar / Wikemedia Commons
But the northern white rhinoceros is not as lucky as its relatives living in the south. Due to illegal hunting, in 2008, the northern white rhinoceros was declared extinct in the wild, leaving only 8 northern white rhinoceros in captivity in the zoo.
In 2009, the Palace Town Zoo on the Rabe River in the Czech Republic(Dvůr Králové Zoo) sent 4 northern white rhinoceros to O. Pejeta(Ol Pejeta) Nature Reserve, they are the female Nagin and Fatou, and the male Suni(Suni) and Sudan. People are pinning their hopes on Africa’s warm climate and vast grasslands. Perhaps this primitive ringThe environment can help the northern white rhinoceros to mate successfully and breed offspring.
Unfortunately, the hope was not fulfilled. Najin and Fatou were not pregnant. A 2014 health evaluation showed that they are not suitable for conceiving offspring: Fatou suffers from uterine disease; Najin’s leg is injured and pregnancy will bring complications.
Nagin and Fatou in O Pejeta Nature Reserve | Ami Vitale / Twitter: @Ol Pejeta
In the past ten years, the few remaining northern white rhinos in the zoo have also died. Neasri in 2011, Angalifu and Suni in 2014, Nabire and Nola in 2015 …
Then, Sudan, who left in 2018-so far, there are only a pair of solitary northern white rhinoceros mothers and daughters on the planet.
Can technology save them?
Natural breeding has no way to go, and the rescue of the northern white rhinoceros can only rely on assisted reproduction, that is, “test tube baby”.
When several male northern white rhinoceros were still alive, researchers had collected their sperm and kept them frozen. If we can get the eggs of Najin and Fatou, fertilize them in vitro, and then transfer the successfully developed embryos into the womb of a surrogate female rhino, we still have a chance to usher in the newborns of the northern white rhinoceros.
But this series of technologies are not simple.
The method of local anesthesia before egg retrieval, and then it will be under general anesthesia | Ami Vitale / Twitter: @Ol Pejeta
In terms of egg retrieval alone, researchers must first anesthetize the rhino, and then remove the egg cells from the ovaries as quickly and accurately as possible; once the anesthesia takes too long or accidentally damages the blood vessels near the ovaries, it will Cause damage to rhinos. The two existing northern white rhinos are too precious. In order to be foolproof, researchers can only explore other rhinos first. Southern white rhinoceros-closest to the northern white rhinoceros, and the number is temporarily at a relatively safe level, so it has naturally become the first choice for researchers.
Since 2014, at least 15 zoos in Europe have given the green light to the egg retrieval technology of the northern white rhinoceros, and they are willing to let their own southern white rhinoceros act as mice. After determining that the technology is feasible , in August 2019, the researchers finally took the eggs of the northern white rhinoceros for the first time.
The egg retrieval process went smoothly. After nearly two hours of anesthesia, both northern white rhinoceros also recovered. A total of 10 viable egg cells were taken out this time. These cells were quickly cryopreserved and sent to the waiting helicopter; after three transfers, they were sent to the laboratory in Italy.
After the egg retrieval operation was completed, this photo was posted on the Twitter of O Pejeta Nature Reserve: “NaJin He Fatu just took a bath in the mud, and it feels pretty good! ”| Jan Zwilling / Twitter: @Ol Pejeta
Of these 10 egg cells, 7 are in a mature state that can be fertilized. At the same time, the researchers resuscitated the previously preserved sperm of the northern white rhinoceros and injected the sperm into the egg cells to complete in vitro fertilization.
After half a month of cultivation and observation, the researchers announced that of these 7 fertilized eggs, 2 have successfully developed into embryos. A few months later, they underwent another egg retrieval operation and this time obtained a surviving embryo.
The 4 egg cells of Fattu and the 3 egg cells of Najin have reached a mature state that can be fertilized | Twitter: @Ol Pejeta
race against time
The time came to 2020, and the sudden outbreak disrupted the plan; it was not until the end of the year that the researchers successfully retrieved 14 egg cells from Fatou and cultivated 2 viable embryos. Unfortunately, Fatou’s mother, Nagin, was unable to provide egg cells this time, and the egg cells previously taken from her failed to produce embryos. Age or health problems may affect her reproduction.
So far, we have 5 embryos of northern white rhinoceros. These five hard-won hopes are currently cryopreserved in liquid nitrogen-They are still waiting for the embryo transfer technology to mature.
If there is sufficient technology, these embryos will be transferred to the surrogate femaleSex in the body of southern white rhinoceros. Currently, researchers are making active attempts for this technology. They will observe and predict the estrus cycle of the surrogate female southern white rhinoceros, trying to find the best time for the embryo to move-but these attempts have only just begun, as Richard Vitch, the head of the O Pejeta Nature Reserve (Richard Vigne) said, “We are still a long way from achieving this goal.”
At the same time, under the premise of ensuring the health of Fatou and Najin, the researchers will continue to collect eggs for the two of them, and cultivate more embryos of northern white rhinoceros, so that they will not be helpless when future transplantation fails.
At the end of last year, scientists collected eggs of Northern White Rhinoceros in Kenya | Rio the Photographer
However, even if surrogacy is successful, genetic diversity is still a major problem. Just as the mother and daughter of Nagin and Fatou are the daughter and granddaughter of Sudan, the sperm and egg cells that can be used in assisted reproduction actually come from a few northern white rhinoceros in a limited number and not far away from each other. The cubs produced in this way may be the product of inbreeding, and the genetic diversity is too low, I am afraid it is not enough to continue to reproduce a stable population.
To solve this problem, you may be able to rely on stem cell technology to induce somatic cells into pluripotent stem cells, which then develop into germ cells, and then reproduce baby rhinos. In 2018, the San Diego Zoo in the United States analyzed their frozen somatic cells of northern white rhinoceros and found that these samples have sufficiently high genetic diversity; if they can be used to create new northern white rhinoceros, these endangered behemoths may be saved.
It’s just that the premise of all this is that this more challenging stem cell technology can be successfully implemented.
In February 2019, scientists injected anesthetics on a southern white rhinoceros in Poland, and then transferred the southern white rhinoceros embryos into her body. However, we did not find any follow-up reports on this embryo transfer. This transfer seems to have failed | Petr David Josek, File / AP
Scientists and northern white rhinoceros are in a race against time. If the newborns of the northern white rhinoceros in the laboratory can be born before the death of Nagin and Fatu, the little rhinoceros can also follow them to learn ancestral survival skills and learn how to become a northern white rhinoceros.
Human greed and arrogance once pushed the northern white rhinoceros and scientists into this race against time. Can we outperform this time? Can the third northern white rhinoceros be ushered back on Earth?
Hope modern technology can bring miracles.
References
[1] https://www.olpejetaconservancy.org/press-release-northern-whites
[2] https://www.nationalgeographic.com/animals/2019/08/plan-save-northern-white-rhino-ivf
[3] https://phys.org/news/2019-08-scientists-closer-northern-white-rhino.htm
[4] http://www.biorescue.org/en/news/happy-end-challenging-year-two-new-northern-white-rhino-embryos- created-christmas-now-there
[5] https://www.africanews.com/2021/02/24/the-race-to-save-the-northern-white-rhino-before- it-s-too-late/
This article is from WeChat official account:Guokr (ID: Guokr42)< span class = "text-remarks">, author: Barley