PRAGYA SANTRA, AMITY UNIVERSITY KOLKATA
The protein-coding genomes for humans and chimpanzees are remarkably similar with a 1% difference. The biological feature that makes us unique and separable from chimpanzees is an intensely debated and interesting line of research.
According to the hypothesis, the researchers claim that it wasn’t so much DNA sequence but the regulation of the genes, performing the maximum activities, which sets humans apart from their ape relatives. Evidence from adaptive evolution highlights mainly the regulatory elements to detect non-coding regions with lineage-specific accelerated evolutionary rates. The field of the study covers the accelerated region of genes responsible for brain and neural development. Positive selection (a hint of the functional relevance of mutation) was noted, based on o higher empirical binding affinity. The greater the substitution-to-polymorphism ratio in sequence, the reduced variance in the expression of neighboring genes.
In comparison to any other organs from the body, the human brain experienced a high level of positive selection. For further confirmations, the researchers used machine learning models with experimental data. These findings explain the proteins involved in gene regulation and bind to their respective regulatory sequences in different brain tissues. Comparative studies and functional annotations were done with the results obtained from the previous observations.
The brain-related cell types having a higher positive selection in humans are functionally associated with cognitive abilities. Astrocytes were marked to impair synaptic and network balances.
Alzheimer’s disease also was found to be related to the atrophy of choroid plexus epithelial cells of the brain. Even human olfactory bulb and cortical plates were found to be more developed due to the beneficial mutations. The cerebellum in humans was also found to be modified more to hold more memory capacities. Recently researchers are more focused on the hypothalamus studies of human and apes’ brains to understand the endocrine evolution of humans. There is more such comparative analysis yet to be done and the research is still in progress.
Also read: Drug Resistivity in Malignant Cells
SOURCE:
Robust inference of positive selection on regulatory sequences in the human brain; Jialin Liu and Marc Robinson-Rechavi; Science Advances; 2020; Vol. 6; no. 48; eabc9863; doi: https://doi.org/10.1126/sciadv.abc9863
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