Here is a thought-provoking hypothesis in this week’s Science about “genomic perfection” versus “cellular survival.” From “Cellular survival over genomic perfection“ (open access):
The high number of passenger mutations, equivalent to 1000 to 10,000 per genome, in normal cells raises questions regarding why DNA quality control mechanisms have failed to limit mutagenesis. Perhaps a somewhat counterintuitive perspective can be considered: If DNA quality control pathways monitor and preserve DNA integrity too strictly, it could be detrimental to cellular survival. The repair of DNA lesions has a cost: It requires time and cellular resources. If every DNA lesion in a cell were repaired, avoiding mutations altogether, the cellular cost associated with performing that repair would have to increase in direct proportion to the amount of damage. In conditions of high DNA damage — through exposure to environmental mutagens, for example — DNA repair could be too costly for cellular survival. [Emphasis added.]
It’s a fascinating idea. I wonder how (or if) it could be tested. Perhaps one would need to engineer utterly obsessive and scrupulous repair systems, like the compulsive cleaning robots in the movie WALL-E, who can’t stand to see even a single mutation in their section of DNA, and compare them to the union-work-rules and somewhat lazy repair systems cells have now.
“Oh, quit your bellyaching, you can survive with a few mutations. You’re alive, aren’t you?” 😉
H/t Dave Carlson at the discussion site Peaceful Science.