A section of the mouse gut imaged with confocal microscopy. Mouse epithelial nuclei are labeled in blue, the mucus layer in green, and bacteria in yellow and red. The large, yellow and golden structures are food fibers. The mucus is thick and continuous as this mouse was not experiencing diarrhea.CAROLINA TROPINI, SONNENBURG LAB, STANFORD UNIVERSITYAn over-the-counter laxative causes more than just the familiar effects of diarrhea. According to a study published today (June 14) in Cell, the make-up of the microbiota and immune system activation changed after mice received a laxative that induced diarrhea for less than a week.
The study suggests that “the idea that the microbiome is acquired early in life and then is just very stable is a bit of an oversimplification,” says Andrew Gewirtz, an immunologist at Georgia State University who did not participate in the work. “In reality, a lot of different things are perturbing the microbiome all the time.”
When she was a PhD student, Carolina Tropini, a biophysicist and current postdoc in Justin Sonnenburg’s lab at Stanford University, noticed that some bacteria responded to osmotic shock—that is, rapid changes in the concentration of water and the molecules dissolved in it—by shrinking, but were able to start growing again once their environment was back to normal.
The microbes in the human gut experience different concentrations of dissolved substances ...
