The research published today in Journal of Biology examines how mutant bacteria respond to different forms of stress, from cold temperature to the inhibition of protein synthesis. Prof. Stanislas Leibler and Dr. Roy Kishony found that, on average, mutants fare better when they are stressed.
"In contrast to the perception that stress always reduces the organism's ability to tolerate mutations, our measurements identified stresses that do the opposite that is, despite decreasing wild-type growth, on average they alleviate the effect of deleterious mutation," write the authors.
The scientists measured the 'fitness' of 65 E. coli strains carrying individual mutations and 12 control strains under normal and stressful conditions, by calculating their growth rates. To do this they developed a method that is a thousand times more sensitive than current methods at measuring bacterial growth rates. All the bacterial strains tested were engineered so that they produced an enzyme from fireflies called luciferase, which emits light. The number of bacteria in a population could then be counted by measuring how much light those bugs emitted. Comparing the rates of growth of control and mutant cells under the different environmental conditions showed that on average, the difference in growth rate was smaller when the bacteria were stressed.
The advantage of sexual reproduction is widely held to be that it allows harmful mutations to be efficiently purged from the genome. Recombination of DNA during sexual reproduction splits up pairs of mutations, increasing t
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BioMed Central
29-May-2003