If you’ve seen a mole rat, it wasn’t in a beauty contest, but we should envy them for their long lives and essential freedom from cancer. Basically, any organism that has cells that grow – meaning every organism – has a chance that some genetic mutation will occur and that it will lead to genes becoming useless or, worse, to originate cancers.
Mole rats are mammals, as we are, and so they have about half of their genome as retrotransposons copying themselves all over the genome. The copies mutate, diverging from useful function. They become what are called pseudogenes… genes making products almost surely useless, or not at all. Sounds like chaos, and it is. That is, unless you are a mole rat. The rats seem to have strongly cut back the action of retrotransposons, since a few million years back.
How did Valerie Kogan and her colleagues at the beleaguered University of the West Bank determine that mole rats stopped making many pseudogenes long ago? They got the genetic sequences in the genomes of the rats and of many other mammals. The longer ago that a pseudogene was formed, the more mutations it has. Voila! The lowered accumulations of the pseudogenes is likely behind the long lifetimes of mole rats. Of course, if you win the rat race, you’re still a rat, but mole rats obviously like each other.
This has been an outreach activity of the Las Cruces Academy, viewable at GreatSchools.org.
Source: Nature 7 Nov 24, p. 11 and Proc. Nat. Acad. Sci. USA
