Can our parents' experiences change our genes?

We all know that the DNA we're born with doesn't change throughout our entire lives, except does it?

Epigenetics is the study of changes in gene activity that do not involve alterations to the genetic code but still get passed down to at least one successive generation. It's thought to be a way in which environmental experiences influence how genes are expressed. This is done using chemical tags (or epigenetic marks) attached to DNA which can turn certain genes on and off. The most common of these tags are a methyl group, when it attaches to our DNA it blocks the proteins and therefore turns that specific gene off.

It's thought that between each generation the epigenetic marks are erased (in cells called primordial gene cells, the precursors to sperm and eggs). This 'reprogramming' allows all genes to be read afresh for each new person. This process is fairly efficient in resetting genes, however some tags manage to escape and therefore pass on to the offspring.

Understanding this mechanism could lead to advances in adult diseases linked to the build up of deviant epigenetic marking such as cancers and aging cells.

How exactly can our environment affect our genes? studies on a rat pup's epigenome show that methyl groups silence the GR receptor in the pup's brain cells and the affection shown by the mother during the pup's first weeks have a significant effect on the pup's DNA. Strong nurturing signals remove the methyl groups and activate the GR gene. This epigenetic pattern remains even when the pup becomes an adult and the gene enables the rats to cope well with stress later on in their lives.

Other animal studies focus on how our diet can change our epigenome.They show that a diet deficient of methyl-donating foods during late fetal/ early postnatal development caused under-methylation of the genome. When certain genes such as the agouti gene are completely unmethylated, the mouse is yellow in colour, obese and prone to diabetes and cancer. However when pregnant yellow mice were fed a methyl-rich diet, their pups were brown and healthy and remained so for the rest of their lives.

Bibliography:
http://www.wellcome.ac.uk/News/2013/News/WTP051486.htm
http://learn.genetics.utah.edu/content/epigenetics/rats/
http://learn.genetics.utah.edu/content/epigenetics/nutrition/

Image Credit: http://learn.genetics.utah.edu/content/epigenetics/nutrition/images/agouti.jpg

Just a TRIM

The other day in biology our teacher decided to show us a video about the immune system and how our cells protect themselves from the threat of a viral infection. One particular part of the video mentioned the protein TRIM 21, I was curious and decided to do some research on what it really was.

When a virus enters the body it is attacked by our immune system, antibodies attach themselves to the virus and usually this paralyses it and makes it easy prey for our white blood cells. However some viruses do manage to escape and then move on the enter the cells. It was thought that once a virus had reached this stage and penetrated the cell, it was infected and the only possible way of preventing the spread of the infection was to destroy itself.

adenovirus being degraded by a proteasome

It was recently discovered that there is one more line of defense inside the cell against the intruder. Antibodies that have attached themselves to the virus stay attached when it enters the cell. Tripartite motif (TRIM 21) is a naturally occurring protein inside the cell which identifies substances marked with antibodies and tags it with ubiquitin. This essentially marks it ready for degradation by the proteasome. The proteasome is an organelle designed to degradate unneeded or damaged proteins and it acts as a big recycler, breaking them down so that they might be used in the construction of new proteins. Once a virus has been marked, the proteasome breaks it down just as it would a protein.

But how can we use this information in producing new therapies to fight viruses? Many are calling it the breakthrough that will could us cure the common cold, surely this can be done by giving us more TRIM 21. This may be done by encouraging the immune system to create more TRIM 21 so that it can be more effective in destroying viruses. Derek Lowe suggests that another solution such as encouraging the production of more antibodies would be the best way. It makes sense, seeing as it's not due to a lack of TRIM 21 that viruses manage to infect cells; it's because sometimes a virus escapes being tagged by antibodies, evading notice and slipping through the defense systems.

I reccomend that you watch this video, a clip from BBC's The Hidden Life of the Cell

Bibliography:
http://www.independent.co.uk/news/science/a-cure-for-the-common-cold-may-finally-be-achieved-as-a-result-of-a-remarkable-discovery-in-a-cambridge-laboratory-2122607.html
http://pipeline.corante.com/archives/2010/11/03/trim21_a_cure_for_the_common_cold_maybe_not_.php

The Canteen at Christmas

Last week the whole school was feeling festive with most people wearing amazing Christmas jumpers (I unfortunately did not have one to wear but improvised with a tinsel scarf, making me look a little bit like a Christmas tree). My friend and I were still helping out on the tills during break, though.

I am one of five canteen prefects in the school and we all thoroughly enjoy helping them out. I personally help in the snack shacks during Monday and Tuesday lunchtimes and also in the canteen during Thursday and Friday breaks. 

It can get so hectic at times that you don't even know what's 5p and what's 50p but we manage somehow. I love helping in the canteen because I get to see behind what makes everything work and you really feel like a part of the team. I have made stronger friends in my fellow prefects and made new friends in the canteen staff. I never imagined how much I'd enjoy it when I initially wrote my name down on a sign-up sheet. I think I've become more responsible as after all you are handling money and it feels good knowing that people trust you to do these kinds of jobs. 

Overall I like the responsibility that the role gives me and I do really enjoy myself as I'm doing something new that I never expected myself doing, I'm learning and dealing with the pressures that it throws at you every day and I'm having fun as well.

- Jess