Date published: 2006/03/03
The seventh lecture of the Darwin Lecture Series 2006 was by Cynthia Kenyon on "Surviving Longer". And entertaining she was (in the fairly typical North American way). She discussed her work on the C. elegans worm, used as a model system for studying ageing. And this is quite interesting work. Her lab discovered that by imparting mutations that damaged the so-called daf-2 gene, you could double the lifespan of an individual. And these long-lived individuals were active for most of their life, they did not just have a lengthened "old age".
Now this gene had earlier been implicated in another phenomenon, the ability of a worm which was faced with a poor environment (in particular, lack of food) to go into an altered "slowed" state called a DAUER for a period of time. But this was only possible for immature worms. And Kenyon's group discovered that the ageing effect instead only had an impact on adult worms. (As she quipped, there's hope for us all.)
The protein that the daf-2 gene encodes is a hormone receptor. And it turns out there are two similar receptors in humans, a receptor for insulin and a receptor for a protein called IGF-1. She mentioned that there were other species (e.g. fruit flies and mice) where there were similar receptors and similar behaviour had now been observed.
Using microarray analysis, her lab showed that daf-2 controls the activities of many genes (not surprisingly). C. elegans has around 20000 genes and they looked at the top 50 picked up by the microarray analysis. She classified these genes into the following categories: antioxidants, chaperones, antimicrobials, metabolic genes and novel genes. Now this is where it really gets complicated. It is not clear which combination of genes is really controlling the ageing process, and it might not be a simple matter.
She mentioned that her lab had found that ageing and age-related diseases were not necessarily intertwined (i.e. you could have one without the other). And similarly reproduction and ageing were also not necessarily intertwined (so not having children does not necessarily make you live longer).
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