One of the fundamental rules of genetics is under assault: the idea that our body treats each copy of DNA instructions, one from each parent, equally. Scientists have discovered that the main culprits challenging this convention are the cells analyzed in the brain, specifically the ones associated with the dorsal raphe nucleus in newborn mice. Researchers have found that it is actually not uncommon for a developing mouse brain to differentially activate one copy over the other in certain instances.
How often does differential activation occur and what does it mean?
The scientists in the study screened thousands of genes to quantify levels of activation for each copy to see if there was a discrepancy. Scientists at the University of Utah School of Medicine have found that in the dorsal raphe nucleus of neonatal mouse brains, 85% of genes differentially activate their gene copies. This region is primarily known for secreting serotonin, which is responsible for the feelings associated with well-being and happiness. In juvenile brains, the phenomenon still occurs, but at a smaller percentage, with the percentage falling to 10% of genes that are differentially activated. This genetic imbalance may help us understand brain disorders and irregularities in the future. It could not only explain susceptibility to certain disease, but also explain why certain individuals are not prone to them as well.
|Huang et al. Diverse Non-genetic, Allele-Specific Expression Effects Shape Genetic Architecture at the Cellular Level in the Mammalian Brain. Neuron, 2017.