PET Caterpillars

Usually found in hospitals, positron emission tomography (PET) scanners are chamber-sized devices that help to diagnose diseases, spotting changes in how tissues metabolise or break down chemical tracers in a similar way to sugars. The approach helps millions of people during diagnosis, but using PET for research on mammals is expensive with many ethical issues. On the hunt for alternatives, scientists turn to caterpillars. Similar enough to humans in their genetics and large enough that their insides can be inspected by PET, the larvae of the tobacco hornworm (Manduca sexta) make excellent model organisms. Here, using electron microscopy the gut of a healthy caterpillar (left) is compared with cells changed by a bacterial infection (right) – mimicking inflammation seen in colitis – which can be reversed with antibiotics. Caterpillars may have lots to teach us not only about how certain inflammatory diseases progress, but also how researchers might improve and expand on techniques like PET.

Written by John Ankers

John Ankers

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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 Anton G. Windfelder and colleagues
• Institute of Zoology and Developmental Biology; Cellular Recognition and Defense Processes, Justus Liebig University Giessen and Experimental Cardiovascular Imaging, Molecular Cardiology, Heinrich Heine University Düsseldorf, Germany
• Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in Nature Communications, November 2022