The Affect We Have on our Children's Genes

Recently, a new study, published by Science Magazine shows that its not just the women who need to keep an eye on their own lifestyle as far as passing things onto their children, men should too.  More explained by Discover Magazine, human traits such as height, weight, intelligence, and more can partially be inherited, and researchers are coining this inheritance as epigenetics.  "Epigenetics refers to the information in the genome over and above that contained in the DNA sequence.  This information takes a number of forms, but the most popular ones scientists have studied relate to the chemical modification (known as methylation and acetylation) of DNA and the proteins called histones that together make up the human genome" (Discover).  In other words, this information helps to influence which form of our genes are expressed and these forms could then supposedly be inherited through generations and "can even persist within a lifetime in a person's tissues and organs, even as their cells are replenished" (Discover).  Therefore, even a person's nutrition and weight during reproduction, can affect the genes inherited by the child; however, both women and men are included in this passing down.  

It has already been proven that a signature epigenetic gene in men's sperm are liked to their child's Autism.  And "they also suggest that if certain factors in a man’s environment disrupt this same epigenetic process during the production of sperm, this could also be an underlying cause of birth defects and disease that may be traceable to the father" (Discover). The way in which both men and women live their lives, are related to the health of their children.  I do not believe that this is an excuse to use genetic counseling, but instead a huge eye opener to watch more carefully at the choices we make in our lifetime.

Cancer May Leave Early Warning Signs in Cheek Cells

According to Live Science, a study has found that mutated cheek cells from smokers can be used for earlier detection of certain cancers. These cancers would include but are not limited to breast and gynecological cancers. A study was conducted by taking cheek swabs from 790 women. It was found that the women who were smokers showed certain variations in the cell associated with certain types of cancers.

Researchers in this study were looking for epigenetic changes within the cells. These changes are associated with cancer development. In this study it was found that there was a signature epigenetic change in those who smoked. While looking for this signature, it was discovered that they were able to differentiate between cancerous tissue and non-cancerous tissue. These included cancers not only localized in the mouth but throughout the body. This signature was also able to predict if precancerous lesions would form into a full-blown cancer.

I found this article to be interesting because cancers could be detected from a simple cheek swab. It was interesting that it was cancers that are not localized to that specific area but throughout the entire body. This article went on to say that researchers had found that cheek cells may be better at indicating epigenetic changing in women than if blood cells were used. Cheek cells showed approximately a 40-fold increase in abnormal genetic activity.

Passing on Stress to Multiple Future Generations

It has been demonstrated before the effects stress can have on future generations in many animals, including humans. One animal that finds itself under the magnifying glass quite often for this study is the snowshoe hare. This species experiences many population booms and busts that can affect many generations in the future. Scientists have shown that during periods of low stress for the hares, their population doubles every year. In response to this, populations of predators of the snowshoe hares also increase. This causes the population of snowshoe hares to plummet. This cycle lasts about 8 to 10 years. What scientists have found the most intriguing about this cycle is the fact that the hare population does not increase right away following a plummet. The population of snowshoe hares remain low for another 2 to 5 years. An ecologist from Pennsylvania State University, Michael Sheriff, examined this cycle and believed there to be an epigenetic explanation. Sheriff says that although the genes themselves have not been altered, the way in which these genes express themselves can be affect by the level of stress snowshoe hares experience during a population crash. Sheriff and his coauthors analyzed data regarding snowshoe hare population cycles and found that the sharper the population declined, the longer it took the population to increase. Sheriff says that during the periods in which the hares are more viciously being hunted, mothers are under very high levels of stress. This caused the mothers to give birth to smaller and fewer babies. The offspring of the stressed mothers have a higher stress hormone, causing their stress reaction system to be more reactive. Although a snowshoe hare may not have directly experienced these traumatic events, the stress is in a way imprinted in their body.

This article is kind of frightening considering that it shows that high levels of stress can have effects on many generations. While the effects of stress on multiple generations has been observed in humans, scientists have yet to study how the severity of stress can affect multiple generations. This research on the snowshoe hare may be a stepping stone to understanding the same phenomenon in humans.

The link to the original article can be found here.

Epigentic Markers Play a Role in Inheritance

Some interesting recent findings have shed new light in the field of genetics. An article by Michael K. Skinner, entitled A New Kind of Inheritance from Scientific American, explains the effects that epigenetic markers may have on future generations. His accidental discovery has led to many more experiments and studies into the mechanisms behind inheriting these epigenetic markers.

Epigenetic markers are methyl groups that chemically attach to the chromosome of a DNA molecule. These are most commonly found when the nucleotide, cytosine, is followed by the nucleotide, guanine, in the sequence of a DNA strand. Epigenetic markers are capable of controlling gene expression, but do not actually alter the DNA sequence in any way. Abnormal changes to these epigenetic markers, or epimutations, can result in deleterious gene expression and even led to cancer.

When Skinner first noticed the possibility of multigenerational epimutations, or mutations in epigenetic markers passed down to future generations, he was collecting data on the effect methoxychlor and vinclozolin played in rat reproduction. These chemicals are common pesticides used in farming and the agricultural industry. They are known as endocrine disrupters, effecting how the signals of hormones form and operate in the reproductive system. A conclusion was drawn that the chemical exposure resulted in an epimutation occurring in the cells responsible for reproduction.

New mechanism of inheritance could advance study of evolution, disease treatment

In recent years, it has come to our attention that genetic inheritance isn't quite as simple as crossing some punnet squares. Some genes actually have the ability to be switched off in response to environmental signals, and then be passed on through generations. This feat is known as epigenetic inheritance. Now, scientists at UMD have discovered a specific mechanism for this transfer in the roundworm Caenorhabditis elegans, one that stuck around for 25 generations. 

To do this, they tracked the production of double-stranded RNA (dsRNA) on a specific gene in the nerve cells. dsRNA has the ability to move through cells and silence matching genes. In addition to moving from somatic cell to somatic cell, they found that the protein also traveled into the germ cells and affected genes there. This allowed for the modification to be present in forthcoming generations.

I found this article very interesting mainly because of the possible impact the finding could have. If the reason for this occurrence is to adapt to environmental changes, than it is possible that evolution could be occurring at a much faster pace than previously thought. Further research on this mechanism in humans, which is a big leap, could also enhance the efficacy of RNA interference gene therapy for genetic diseases. 

Main article: http://www.sciencedaily.com/releases/2015/02/150202212449.htm
Second Article: http://www.cam.ac.uk/research/news/scientists-discover-how-epigenetic-information-could-be-inherited