If you forget your sun cream, your mitochondria remember!

CONSIDERING the number of overcast days Ireland experiences, most people look forward to the summer, when there are greater chances of sunny days to plan outdoor activiites. If you have ever pressed the palm of your hand against the lens of a lit torch, you’ll know that light can penetrate human skin, but the bulb in a torch only generates harmless visible light.

The sun’s rays that reach the earth’s surface contain a spectrum, from infrared through to ultraviolet (UV) light, as well as all the colours of the rainbow.

Sunlight is energy, and this energy interacts with our skin in the form of waves; longer wavelengths are felt as heat radiation, mid-sized waves are seen as visible colours, and short high energy waves are not detectable using any of our senses. It’s these higher energy UV waves that can do us harm if exposed to them for too long.

If you have ever been caught out in the sun too long you may know the pain of sunburn; this damage fades in a few days, but will have also undoubtedly damaged your DNA, the blueprint for every cell in your body. Not much, and likely insignificantly, but what if you damage it a tiny bit more, and a tiny bit more?

Fear not, as our cells are used to this and in fact have repair mechanisms to cope, except for DNA damage that occurs within our mitochondria.

These are capsules within the cell that act as engines, producing all the energy a cell needs, and they have their own special sort of small circular DNA.

So shouldn’t damage to this type of DNA be of concern too? The answer is both yes and no. Clearly DNA damage is a bad thing, but our mitochondria have hundreds or even thousands of copies of the same DNA within each cell, so that if one is damaged, there are many undamaged copies to compensate. That’s

where my research comes in.

My supervisor, Dr James Murphy, had the idea this damage accumulation acts like a record of a person’s sun exposure history over the course of their life. My research targets the development of a suite of damage markers so that we can identify damage earlier and earlier and even predict serious damage before it occurs, helping people to reduce their risk of future skin problems.

So, a scientist looking at your mitochondrial DNA would be able to say “time to put on more sunscreen” before you even feel the heat!