Saturday, May 09, 2009
Epigenetics
Epigenetics is defined as the study of
- Changes in gene expression which occur in organisms with differentiated cells, and the mitotic inheritance of given patterns of gene expression, and
- Nuclear inheritance which is not based on changes in DNA sequence
Epigenetic factors that can influence the behavior of genes include:
1. Chromatin structure – how DNA is packed
2. DNA methylation – turning genes off
3. Small RNAs – made from DNA and can influence gene behavior in many ways
Our genetic code, the actual sequential structure of our DNA, can pretty much shrug off the influence of any external environmental factors, short of massive radiation. However, the expression of individual genes within that sequence can be permanently altered by such seemingly innocuous influences as diet, exercise, sensory input, lifestyle or how others treat us (socialization). Once triggered, a group of molecules called a methyl group attaches itself to the control centre of a gene, permanently switching on or off the manufacture of proteins that are essential to the workings of every cell in our body. In most tumors, this DNA methylation pattern has been knocked awry, leading to a gene being completely deactivated or triggered to abnormally high activity.
Now, scientific evidence is emerging that these externally driven changes in the behavior of our genes might be passed down through the generations. For example, recent research has demonstrated that the sons of men who began smoking before puberty were more prone to obesity.
All of a sudden, we're staring personal responsibility in the face. Not only can our bad habits or noble attempts at clean living permanently change the way our genes act within us, they could very well have a significant impact on the quality of our children's lives. If DNA is the hardware of inheritance, the epigenetic operating system is the software, controlling the 30,000 genes that carry instructions for the proteins that make up our bodies and keep them running.
If left alone, the epigenetic changes that bad or good behaviors (sensory input) causes in research animals not only lasted a lifetime but was inherited.
The traditional idea that we are the passive carriers of our genes is being challenged by the notion that we are their custodians. Our lifestyles — what we eat, what drugs we ingest, how we utilize chiropractic care, how much we exercise, whether we smoke — plays a role in a chemical switching system that activates or deactivates our genes. There are signs that our behavior may program sections of our children's DNA, and that how we live may even affect our grandchildren's genes.
