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
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences (the new name for the MRC Clinical Sciences Centre) the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.