Nod Off

Early life develops in a careful balance of chemicals released, signals sent and cells changing at just the right time. Imagine then, the impact of a bacterial infection during these delicate stages. In this developing small intestine of newly-born mice, finger-like projections known as villi (shown outlined in pink stretching inwards) usually develop to absorb important chemicals. Scientists find shorter villi in mice infected with E. coli bacteria (Top left compared to bottom left). Oddly, removing a protein called NOD which usually helps to detect bacterial infections (right) restores the villi to near normal length. Researchers believe that, although NOD is essential to defending the growing intestine, early infection can trigger an immune response so strong that it delays development, and the colonisation of the intestine by 'friendly' bacteria. Such disruption to the gut-brain axis in mice and humans alike may be reversed by certain probiotics.

Written by John Ankers

John Ankers

Writer

A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Image from work by Jungjae Park and colleagues
• Department of Anatomy, Physiology, and Cell Biology, Weill School of Veterinary Medicine, University of California, Davis, CA, USA
• Image originally published with a Creative Commons Attribution – NonCommercial – NoDerivs (CC BY-NC-ND 4.0)
• Published in Proceedings of the National Academy of Science (PNAS), September 2026