Science Briefs By Globe Staff, 10/23/2001 Ultraviolet and rings of bacteria If you shine ultraviolet light on a colony of soil bacteria, they run toward the borders of where they live, leaving a hole in the middle, which is a pretty strange thing to do. Anna M. Delprato and colleagues at Clark University in Worcester discovered the effect and have advanced a possible interpretation. The researchers think the ultraviolet radiation makes the bacteria more sensitive to the waste products that tend to pile up in the middle of the colony. The presence of such complex and unexpected reactions to ultraviolet light even in a simple organism is of particular interest as we gradually wear away our protective ozone layer: Who knows what else might start to act in strange and surprising ways? ref.: Physical Review Letters, Oct. 8, 2001. This story ran on page C2 of the Boston Globe on 10/23/2001.