In recent years, China, a center for studies of non-human primates, has accustomed us to the first scientific discoveries depicting beautiful little apes. At the beginning of 2014, the magazine cell It revealed the birth of Lingling and Mingming, the first two primates whose genomes were edited using Cripsr-Cas9, then a completely new DNA editing technology. In 2018, there was Zhong Zhong and Hua Hua, the first successful cloning of two primates, 22 years after Dolly the sheep was cloned in Edinburgh (UK). At the beginning of 2019, five more cloned Chinese macaques, copies of a specimen genetically modified to cause disruptions to circadian rhythms, saw some resonance, followed by other unidentified monkeys with partially human brains.
Not a small name, too, for the crab-eating macaque No. 10, who was born two and a half years ago in Shanghai and It was presented on November 9 in the magazine cell by a team led by Chen Liu (Institute of Neuroscience of the Chinese Academy of Sciences, Shanghai). With its eyes and nails glowing green under the fluorescent light, the tiny animal only survived ten days before its health deteriorated to the point of having to undergo euthanasia. It is the first example of a chimeric ape being born containing a high concentration of cells coming from an individual other than the fetus from which it came.
Scientists have known how to make such chimeras in mice for more than thirty years. This technology allows obtaining genetically modified lines that can serve as models for studying human diseases. But in non-human primates, this treatment remains ineffective and very expensive.
The birth of “number 10” could pave the way for such models in primates. The recipe remains complex and incomplete. It consists of first extracting stem cells from the first macaque embryo and genetically modifying them – in this case to make them express green fluorescent protein (GFP) from the jellyfish. These embryonic stem cells are then introduced into another embryo that is grown in the laboratory. The whole thing is then implanted into a surrogate mother.
Transformation into a form of interspecies chimerism
Chinese researchers had to test many combinations of cultural media for this “graft” to be accepted. Once again, the 74 embryos showed clear signs of fluorescence transferred to forty surrogates, resulting in only twelve pregnancies and six full-term births being recorded. But ultimately, chimerism was only maintained in the aborted male fetus and in “No. 10” – the male who received female cells! Everywhere else, the host embryo has removed the donor cells.
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