Genome complexity:neurons' DNA differs from others (Introduction)

by David Turell @, Wednesday, May 03, 2017, 22:17 (2521 days ago) @ David Turell

Scientists are finding that neurons in the brain have many different DNA patterns. To me this is not surprising. As a person grows up from childhood, each personality will use their brain differently and the brain will respond with a 'use pattern' in which different neurons will be used differently. I don't know why the scientist are surprised at their findings:

https://www.scientificamerican.com/article/scientists-surprised-to-find-no-two-neurons-...

"Accepted dogma holds that—although every cell in the body contains its own DNA—the genetic instructions in each cell nucleus are identical. But new research has now proved this assumption wrong. There are actually several sources of spontaneous mutation in somatic (nonsex) cells, resulting in every individual containing a multitude of genomes—a situation researchers term somatic mosaicism....There are reasons to think somatic mosaicism may be particularly important in the brain, not least because neural genes are very active.

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"Somatic mutations can occur in multiple circumstances. They may emerge during DNA replication or from DNA damage (caused by free radicals or environmental stresses) combined with imperfect repair machinery. In addition to SNVs, mutations known as “indels,” involving insertions and deletions of small DNA sequences (typically tens of nucleotides), also occur frequently. Larger, rarer mutations include structural changes in chromosomes, either in the form of gains or losses of whole chromosomes or copy number variants (CNVs), in which the number of repetitions of long chunks of DNA (covering multiple genes) is altered. Within genomes there are also “mobile genetic elements” that act almost like parasites, jumping around or making copies of themselves and inserting themselves elsewhere in the genome, seemingly to ensure their survival. These strange entities are an active field of research in their own right: they are important here because they can cause somatic mutations, including a type known as mobile genetic element insertions, or MEIs. They are switched on in the same way as genes involved in producing new neurons, making them especially active in the brain during development.

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"There are also plans to collaborate with other NIMH initiatives including BrainSpan, which maps gene expression during brain development, and psychENCODE, which is mapping the brain epigenome (environmentally driven modifications of DNA that influence gene activity without changing the genetic code)."

Comment: DNA is the same throughout the body to start with, but in each organ it is modified to set up the machinery for that organ. In the brain use must cause changes, and since neurons last for life, they must be able to change and adapt. this paper describes the start of this new research into this aspect of brain function.


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