Evidence of internal stress induction

[yoavram]

Editor:

I'd like to see one or two sentences outlining that it is reasonable to consider low fitness -- arising from a maladapted genotype (in reality, aren't almost all genotypes maladapted?) rather than a potentially mutagenic environmental stress like starvation -- as a stress that might induce SIM. I see one reference on this point, but it would be nice to note explicitly any evidence that comes from a bacterial system.

[yoavram]

After discussion with Lilach: Write about how one deleterious mutation can affect fitness and increase stress, like in lac- assays. Also, in general, starvation and other stresses that individuals can adapt to can therefore be interpreted as maladaptation in the genome and can be viewed as a deleterious mutations.

[yoavram]

Cirz et al. 2005 show that the antibiotic drug ciproflaxin induce mutagenesis in pathogenic E. coli and that this mutagenesis is neccessary for bacteria to evolve resistance to ciproflaxin. These findings are extended by Gutierrez 2013 for more bacterial species, different drugs, and more mulecular mechanisms.

Shee et al. 2011 shows that starvation induced mutagenesis depends on functional error-prone polymerases and can be induced in non-stressed cells by activating stress responses. Therefore, starvation is not mutagenic on its own but rather induced stress responses which activate mutagenic programs which in turn turn off when starvation is over.

However, I can't find direct evidence of down regulation of mutagenesis after adaptation to the stress.

[yoavram]

Another reference is Yeiser et al. 2002 which shows that during stationary phase bacteria use error-prone polymerase and accumulate mutations that generate a growth advantage during stationary phase (GASP) phenotype.