Meet Twiggy

What makes us the shape we are? That’s a big question in biology, and it’s one that these fruit fly maggots (pupae) are helping scientists to answer. The bottom one is a normal pupa, fat and plump, while parts of the upper two have an unusual ‘twiggy’ shape. These twiggy regions correspond to areas that have been genetically modified to switch off a gene called Obstructor-E (Obst-E), which encodes one of the proteins making up the sturdy ‘skin’ (cuticle) of a maggot. Usually, the cuticle of a thin, wriggly maggot shrinks lengthwise and expands widthwise as it changes into a pupa. The lack of Obst-E changes the physical properties of the cuticle so it can’t expand properly to create the characteristic plump shape. Although humans don’t go through a pupal stage, similar genes and physical forces might also be involved in creating tubular structures within our bodies, such as the gut.

Written by Kat Arney

Kat Arney

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Dr Kat Arney is an award-winning science writer, broadcaster and public speaker, and is the founder and Creative Director of First Create The Media.

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• Image from work by Reiko Tajiri and colleagues
• Graduate School of Frontier Sciences, The University of Tokyo, Chiba, Japan
• Image originally published under a Creative Commons Licence (BY 4.0)
• Published in PLOS Genetics, January 2017