The human brain has increased in sized quite significantly in the evolution of mankind and is what makes us very different from our closest genetic relatives, the chimpanzees. Thanks to the way our brain functions we are able to reason, use language and so on. Now, researchers from Duke claim they have uncovered the mystery behind evolutionary brain expansion.
The scientists proved it is possible to select some key alterations in DNA to compare chimpanzees and people and observe their role in early brain development. For their experiment the group at Duke used mouse embryos.
They discovered that people are outfitted with minor differences in a specific regulator of gene dynamic, named HARE5. When the regulator was introduced into a mouse fetus it prompted a 12 percent larger brain than in the fetuses treated with the HARE5 sequence taken from chimpanzees.
The research, available online in Current Biology, might help understand what makes the human mind unique as well as why individuals develop some medical conditions like autism or Alzheimer’s but chimpanzees don’t.
Each genome encompasses numerous little pieces of DNA called “enhancers,” which are controlling genes dynamic. Some of these are only found in people and some are active only in particular tissues. Anyhow the human-only enhancers are not believed to have any direct effect on brain anatomy.
In the new research the specialists loaded genomic information from people and chimpanzees, to discover enhancers present mainly in the brain tissue. They chose the enhancers that varied notably between the two species.
The team’s first rundown showed up 106 contenders, six of them being believed to contribute to barin development. These were named “human-accelerated regulatory enhancers”, starting from HARE1 to HARE6.
The best contender was HARE5 due to its chromosomal area close to a gene called Frizzled 8, which known to be connected with brain activity and diseases. The Duke group chose to focus on HARE5 and afterward showed that it was a possible enhancer for Frizzled8 thanks to two DNA sequences that were directly connected to brain cells.
Delivering a short rundown of solid contenders was an important step, completed by applying the right filters to the investigation of human and chimpanzee genomes, according to co-creator Gregory Wray, biology professor and chief of the Duke Center for Genomic and Computational Biology.
The Duke group intends to study the human HARE5 and chimp HARE5 mice into adulthood, for other differences in brain structure and conduct. The team likewise plans to investigate the contribution of the other HARE sequences to brain development.
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