Genomic islands and radiation resistance fitness through global conventional and unconventional methods applied to and genera

Sghaier, H.*; Narumi, Issei; Barkallah, I.*

Central to the evolutionary concept of a radiation-resistant cell is the notion of adaptation. Two hypotheses were that the radiation resistance phenotype of and was due to some adaptations to desiccation and high temperatures, respectively, which implies genetic transfer from various donors for two distinct adaptations unless a common ancestor, predisposed to radioresistance and hyperthermophily, existed. As acclimation entails genetic acquisition or geno-phenotypical change, this controversy over the adaptive evolution of radioresistant cells cannot be isolated from the presence of potential genomic islands (GIs) in the flexible genomic pool of and , model radiation-resistant genera. Our data suggest that present GIs do not reflect a common or ancestral trait among analyzed radiation-resistant organisms. Thus, common mechanisms of radioresistance among prokaryotes do not include GIs.