A brief article regarding DNA/genes and expression/non-expression et al:
Epigenetics
“Learning itself consists of nothing more than switching genes on and off.”
Matt Ridley
Out of our 30,000 genes, only two percent of DNA codes for proteins. Until very recently, much of our DNA was considered to be what researchers call junk DNA. These genes were considered to be the byproduct of millions of years of evolution – genes were still inherited but were no longer used. Recently, however, scientists have discovered that some of this junk DNA actually switches on RNA that interacts with other genes.
The field of research of these phenomena is epigenetics. Epigenetics is the science of turning genes on- and-off with nutrients and other chemicals, resulting in changes of expression of those genes. The process of suppressing and enhancing genes is called methylation, a chemical process that, among other things, aids in the transcription of DNA to RNA and is believed to defend the genome against parasitic genetic elements called transposons.
Transposons are spans of DNA that – through a process called transposition – can actually move to different positions within the genome of a cell.
Transposition was first observed by researcher Barbara McClintock; this discovery earned her a Nobel Prize in 1983. As a result of her work, geneticists now know that this process can be activated by changes in diet, drugs, and exposure to toxins, and can permanently change a person’s DNA.
More fascinating is the finding that these mutations may be inherited by children. Environmental toxins have been shown to alter the activity of genes through at least four generations after exposure. For example, women who smoke while pregnant double the risk of asthma in their grandchildren.
For this reason, no two brains are alike, including those of identical twins. It is thought that about 40 percent of our genes can be modified epigenetically. Although identical twins share the same DNA, their epigenetic material can be different. Moreover, the older the twins become, the more discrepancies will occur in their DNA. Fifty-year-old twins have four times as many differentially expressed genes than three-year-old twins.
Even more interesting is the discovery that genes are regulated by maternal care. Thus far, at least nine hundred genes can be altered by maternal care. For example, the presence of a variation in the monoamine oxidase A gene (MAO-A) combined with maltreatment predicts antisocial behavior.
In mid-2009, researcher Moshe Szyf at McGill University reported that commonly-used pharmaceutical drugs can cause such persistent epigenetic changes. Szyf and his co-author Antonei Csoka posit that drug-induced diseases, such as tardive dyskinesia and drug-induced lupus, are epigenetic in nature. (More about Lupus below.) They also propose that epigenetic changes from pharmaceuticals may be involved in heart disease, obesity, diabetes, infertility and sexual dysfunctions, as well as neurological and cognitive disorders.
Smoking can cause changes in gene function. As stated earlier, there is compelling evidence that prenatal smoking increases the incidence and severity of ADHD. The risk of a severe type of ADHD greatly increases in children whose mothers smoked during pregnancy and who also have variants of one or two genes associated with ADHD – one on chromosome 11 and the second on chromosome 5. Interestingly, even children of mothers who smoked during pregnancy who didn't fit all of the criteria for ADHD had more symptoms of the disorder. This was true if they had been exposed to cigarette use in utero or had genetic variations related to risk.
28 Apr 2015, 2:37 pm
for supporting trump. Because doing so is deplorable.
