Swallowing food, digesting it, and finally excreting the waste at the other end depends on peristalsis – the involuntary muscle movement that transports and mixes food substances as they pass through the gastrointestinal tract. Although these rhythmic muscle movements are essential for feeding and digestion in animals as diverse as humans and simple invertebrate hydra, very little is understood about what controls the process. Now scientists have discovered that, in hydra at least, peristaltic contractions (a typical cycle of which is shown) are regulated in part by the organisms’ own microbes. Removing the microbiota from hydra caused peristaltic contractions to diminish in frequency and regularity, while restoring the microbes (or their secretions) prompted more typical contractions. Given that disrupted microbiomes have been associated with gut motility disorders in humans, the new research suggests that gut microbe imbalance may not simply be a consequence of such disorders, but possibly a cause.
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