The human brain, relative to our size, is the largest among mammals. What genetic elements determine the size of the brain of a species? Until recently, this question remained unanswered. The researchers showed that specific molecules, RNAs, are involved.
Brain size is embedded in the genes of one species, so it varies little, except in cases of disease, between individuals of the same species. However, even among different mammalian species, a large proportion of the genes that control the size of the cerebral cortex are identical. However, it is the size of the cerebral cortex, the outer part of the brain, that determines the size of the latter.
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The brain: the role of microRNA
recent studyBy researchers at the Instituto Neurociencias in Alicante, Spain, they showed that microRNAs play an important role in brain size. RNA is known for its role as a messenger between DNA and the formation of proteins. In the case of these small RNA molecules called micro RNAs, it is different: they do not produce proteins but have the function of regulating genes.
In their study, the scientists focused on a microRNA in particular, called MIR3607, and its genetic history. They discovered that the fact that this gene was no longer expressed in some rodents such as mice led to the reduction in their brain volume that occurred during development. Additionally, by artificially expressing MIR3607 in mice, the researchers observed an expansion of the brain’s ventricular region.
If researchers focus on microRNA, this finding demonstrates the importance of these long-overlooked molecules in studies of brain development and expansion.
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