Surviving the Stress:  Radiation Effects in Microbes

Dr. Linda C. DeVeaux
Idaho Accelerator Center and the Department of Biological Sciences
Idaho State University

Irradiated cells display direct effects ranging from transient changes in gene expression to irreparable DNA damage.  
Much of the damage results from generation of short-lived radical species, which, in turn interact with DNA.  Direct
effects range from transient changes in gene expression, such as adaptive response, to irreparable DNA damage,
resulting in death.  Moderate direct effects include persistent changes in growth characteristics, as well as delayed
genomic instability. Bacteria and simple eukaryotic organisms provide excellent model systems for studying these
direct radiation effects. In addition, unirradiated cells that are grown in the vicinity of irradiated cells also display
dose-dependent effects.  These "Bystander" effects, first seen in mammalian cells, are activated by a signal from the
damaged cell.  Using unicellular cells, long thought to grow independently from each other, we have demonstrated
radiation damage-induced communication between microbial cells in culture.  These intracellular (direct) and
intercellular (indirect) damage signals may represent means of ensuring survival of a species in the face of rapidly
changing environmental conditions.