Pulsating Response to Stress in Bacteria Discovered

http://www.sciencedaily.com/releases/2011/11/111103120607.htm


By attaching fluorescent proteins to the genetic circuit responsible for B. subtilis's stress response, the researchers can observe the cells' pulses as green flashes. Watch a video of the flashing cells as they multiply over the course of more than 12 hours at: http://www.youtube.com/watch?v=qWkLS-u982A (Credit: Caltech/Elowitz Lab)


In their experiment, the researchers studied how a bacterial species called B. subtilis responds to a stressful environment -- for example, one without food. In such conditions, the single-celled organism activates a large set of genes that help it deal with hardship, by aiding cell repair for instance. Previously, biologists had thought the bacteria would handle stress by turning on the relevant genes and simply leaving them on until the stress goes away.

Instead, the researchers found that B. subtilis continuously flips these genes on and off. When faced with more stress, it increases the frequency of these pulses. The pulsating action is like switching your heater on full blast for a brief period every few minutes, and turning it on and off more frequently if you want the house to be warmer.

"It's a very different view of how a cell can respond to a particular stress," says James Locke, a postdoctoral scholar at Caltech. Locke and graduate student Jonathan Young are the lead authors on a paper describing this work, which was published in the Oct. 21 issue of Science.