In vivo measurement of muscle output in intact Drosophila

We describe our methods for analysing muscle function in a whole intact small insect, taking advantage of a simple flexible optical beam to produce an inexpensive transducer with wide application. We review our previous data measuring the response to a single action potential driven muscle twitch to explore jumping behaviour in Drosophila melanogaster. In the fruitfly, where the sophisticated and powerful genetic toolbox is being widely employed to investigate neuromuscular function, we further demonstrate the use of the apparatus to analyse in detail, within whole flies, neuronal and muscle mutations affecting activation of muscle contraction in the jump muscle. We have now extended the use of the apparatus to record the muscle forces during larval and other aspects of adult locomotion. The robustness, simplicity and versatility of the apparatus are key to these measurements.

► We describe an apparatus for measuring muscle outputs from small intact insects. ► The apparatus is based on an optical fiber as a flexible beam transducer. ► Transducer system developed to measure forces in jumping adult Drosophila. ► New applications to measure muscle outputs in walking, crawling and gripping. ► A novel use to measure parameters of muscle contractions in larval crawling.