Mobile self-splicing introns and inteins as environmental sensors

•Mobile self-spicing introns and inteins have been surmised to play a regulatory role.•There is mounting evidence that these elements respond to environmental cues.•Stressors can affect splicing and induce mobility of self-splicing introns.•Inteins can be stimulated to splice by a spectacular array of stressors.•The emerging picture is one of adaptation of these parasitic elements to their hosts.

Self-splicing introns and inteins are often mobile at the level of the genome. Although these RNA and protein elements, respectively, are generally considered to be selfish parasites, group I and group II introns and inteins can be triggered by environmental cues to splice and/or to mobilize. These cues include stressors such as oxidizing agents, reactive oxygen and nitrogen species, starvation, temperature, osmolarity and DNA damage. Their sensitivity to these stimuli leads to a carefully choreographed dance between the mobile element and its host that is in tune with the cellular environment. This responsiveness to a changing milieu provides strong evidence that these diverse, self-splicing mobile elements have adapted to react to prevailing conditions, to the potential advantage of both the element and its host.