Science heavyweight! The human brain gene triggers monkeys to grow larger brains.

, June 22, 2020 /PRNewswire-bio-valley s/bio-valleys /PRNewswire/ -- The expansion of the human brain in the evolutionary process, especially the expansion of the new cerebral cortex, is related to cognitive abilities such as reasoning and languageA gene called ARHGAP11B, expressed only in humans, triggers the brainstem cellsform morestem cells, which is a greater prerequisite for the brainPast studies have shown that when ARHGAP11B is expressed at non-physiological lysac levels in mice and ferrets, it leads to the expansion of the new cerebral cortex, but its correlation with primate evolution is unclearResearchers at the Max Planck Institute for MolecularCell BiologyandGenetic stoic(MPI-CBG) at the Max Planck Institute of, in collaboration with colleagues from the Kawasaki Central Institute of Research in Japan (CIEA) and Keio University, found that when this gene is expressed at the physiological level of the human body, it causes the cerebral cortex to swellThis suggests that the ARHGAP11B gene may have led to the expansion of the cerebral cortex during human evolutionThe researchers published their findings in the journal Science, entitled "Human-specific ARHGAP11B size and folding of the primate neocortex in the fetal marmoset."Photo Source: Heide et al.  MPI-CBG "Humans' new cerebral cortex is the youngest in evolution, three times larger than the cerebral cortex of a close human cousin, a chimpanzee." During evolution, the folds of the new cerebral cortex increase to accommodate limited cranial space A key question for scientists is how the human new cerebral cortex has become so large In a 2015 study, Wieland Huttner, founding director of MPI-CBG, found that under the influence of the human-specific gene ARHGAP11B, mouse embryos produced more neuroprogenial cells and could even fold the normally expanded neocortex The results show that the ARHGAP11B gene plays a key role in the evolutionary expansion of the new human cortex the rise of human-specific genes
about 5 million years ago, the human-specific gene ARHGAP11B was a partial copy of the commongene ARHGAP11A, which evolved along the evolutionary lineage that led to Neanderthals, Denisova and now humans, where chimpanzees formed after the lineage was separated from chimpanzees In a follow-up study in 2016, Wieland Huttner's team found surprising reasons why the ARHGAP111B protein contains 47 human-specific amino acid sequences that were not found in the ARHGAP11A protein and are critical to ARHGAP11B's ability to increase the of brain stem cells specifically, a C-to-G base replacement found in the ARHGAP11B gene resulted in the loss of 55 nucleotides in the ARHGAP11B messenger RNA, leading to changes in the reading box, resulting in a human-specific, functionally critical sequence of 47 amino acids This base replacement may occur much later than when the gene appeared (about 5 million years ago), about 1.5 to 500,000 years ago This point mutation is not uncommon, but in the case of ARHGAP11B, the advantage of forming a larger brain seems to immediately affect human evolution genes affect monkeys
however, it is unclear whether the human-specific gene ARHGAP11B also leads to the growth of the new cerebral cortex of non-human primates To study the issue, Wieland Huttner teamed up with Erika Sasaki of the Central Institute of Experimental Animals (CIEA) in Japan and Hideyuki Okano of Keio University in Keio, which pioneered a technique that could produce genetically modified non-human primates The study's first author, postdoctoral fellow Michael Heide, travelled to Japan to work directly with colleagues in the field they produced genetically modified common velvet monkeys, a new world monkey, developing a new cerebral cortex that expresses the human-specific gene ARHGAP11B, but they usually do not Japan, like Germany, has the same high ethical standards and regulations in animal research and animal welfare The brains of 101-day-old common velvet monkey fetuses (50 days before normal birth) were obtained in Japan and sent to MPI-CBG for detailed analysis Photo Source: Heide et al.  Michael Heide, MPI-CBG, explains: "We did find that the cerebral cortex of the average velvet monkey is enlarged and the surface of the brain is folded Its cortical plate smaller than normal In addition, we can see an increase in the number of glial progenitor cells in the lower base of the heart and the upper neurons, which increased during primate evolution "The researchers now have functional evidence that ARHGAP11B led to the expansion of the new cerebral cortex in primates "Our analysis is limited to the baby monkey fetus because we expect this expression of this human-specific gene to affect the development of the new cerebral cortex of the skin monkey," added Wieland Huttner, who led the study ethical considerations
adding Given the unforeseen consequences of brain function after birth, we believe that this is a prerequisite -- and ethically mandatory -- that is, first of all, to determine the effect of ARHGAP11B on the development of the new cerebral cortex of fetal velvet monkeys "
researchers believe that these results suggest that the human-specific ARHGAP11B gene may have led to the expansion of the new cerebral cortex during human evolution (BioValleyBioon.com) References: Human brain size gene triggers bigger brain in monkeys "
Human-specific ARHGap11B sans size and folding of the primate neocortex in the
" Science (2020) DOI: 10.1126/science.abb2401
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