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telomeres

Telomeres are protective caps found on DNA strands. These are stretches of DNA which protect our genetic code. They are often compared to the tips on shoelaces as they stop chromosomes from fraying and unravelling and keep the code stable. After each cell division they shorten. In this way the cell is programmed to self destruct after a certain number of divisions after which the telomeres become too short.

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The BMJ recently published the results of a large prospective cohort study of 121 700 nurses enrolled in 1976.This study showed that those women who  ate a Mediterranean diet type diet had longer telomeres on their white cells when their blood was tested. This provides further evidence that telomere length is either a marker of ageing or has a causative role.

shoelaces

Telomerase is an enzyme which adds bases to the ends of telomeres to prevent them shortening. It stops telomeres wearing down in young cells;however after a while there is not enough. Could enough telomerase make cells immortal? Cancer cells produce telomerase in large quantities and some do not undergo apoptosis [self destruction] and may be ‘immortal’. Scientists have been able to make cells undergo far more divisions in labs than normal by using telomerase and cells have not become cancerous which is encouraging.

Understanding telomeres may even help treat cancer. If we can stop telomerase cancer cells will age and die. In a study researchers blocked telomerase in tissue samples of breast and prostate cancer causing the cells to die. How this could be used in practise without ageing ordinary cells is not known as yet.

 

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In 2010 researchers at Harvard used prematurely aged mice created by engineering them with a switch that enabled them to turn off telomerase. The switch allowed the scientists to find out whether reactivating telomerase in the animals would restore telomeres and stop the signs of ageing. It did and a dramatic reversal of many aspects of ageing, including reversal of brain disease and infertility, testes actually increased in size and brains regenerated.

I recommend reading the articles below.

http://www.nature.com/nature/journal/v469/n7328/full/nature09603.html

http://learn.genetics.utah.edu/content/chromosomes/telomeres/

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