Stressed Bacteria Time Lapse Movie
Image (right): Bacteria infecting a very brave macrophage. Artificially coloured scanning electron micrograph (SEM) of Mycobacterium tuberculosis bacteria (purple) infecting a white blood cell (green). The macrophage will (try) to engulf and destroy the bacteria as part of the body’s immune response (phagocytosis).
Sigma B is thought to be a major regulator in bacterial stress. Release of the protein can be triggered by many differend stressfull environmental conditions such as extreme temperatures or starvation. Scientists studied the sigma B protein in bacterial cells. And found that when released sigma B can activate over 150 genes. In the short time lapse movie below the bacteria (B. subtilis) are modified to glow green when sigma B springs into action. During growth they are exposed to a stress causing chemical. Much as expected the sigma B protein is activated. But then, to our surprise also, the protein is quickly switched off again while the chemical is still present in the environment. Instead of shifting from one steady state to another steady state the sigma B regulatory protein is released in pulses. This definitely requires more research, but for now, it is a fascination short bacteria Time Lapse movie. Enjoy!
About the makers of this movie: Researchers at the California Institute of Technology have found a new kind of stress response in a bacterial species called B. subtilis. Instead of just shifting from one steady state to another and staying there, the cells deal with stress—such as the lack of food—by activating a regulatory protein in steady pulses. The cell cranks up the frequency of the pulses if there’s more stress. By attaching fluorescent proteins to the genetic circuit responsible for B. subtilis‘s stress response, the researchers observed each pulse as a green flash. To read more on this research project, go to http://www.caltech.edu/article/13470 (Credit: Caltech/Elowitz Lab.)