Saturday, April 14, 2012

Linking Exercise and Mutation Rate

Dendrobatidae are a family of frogs, commonly known as poison dart frogs.  They are most famous for their brightly colored skin and toxic secretions.  However, researchers have recently discovered an interesting new quality in these frogs.  The more physically active species of Dendrobatidae accumulate changes to their genetic information faster than frogs species that are less active.

These different species are defined by the fact that they interbreed and are able to produce normally functioning offspring.  The idea that more active cold-blooded animal species would experience faster changing genomes is not new.  Studies in the past have not been able to support this hypothesis; however, they all studied animals while they are resting.  A new study conducted by Juan C. Santos tested animals during periods of activity comparable to activity they would perform in nature.

The study subjected about 50 different frog species to physical exercise (running for four minutes).  Then, their oxygen uptake was measured and compared across the different species.  The results showed that the more active species had a higher oxygen capacity.  They were able to use their oxygen more effectively during the aerobic activity.

He then compared 15 different genes from the different frog species and created a poison dart frog family tree.  This tree showed that more active frog species experienced faster changes in these genes.  One hypothesis for this rate of change difference is that exercise releases molecules that are likely to mutate DNA.  These molecules (called reactive oxygen species) are mainly given off when the body has stopped its physical activity and circulation and oxygen levels are returning to normal.  However, the true mechanism for this difference in mutation rate remains unknown.

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