Extreme Elastic Properties of Mechanosensory Chordotonal Organs in Drosophila melanogaster

Mechanosensory organs convert mechanical stimuli into biological signals, thereby activating various biological processes, including hearing, touch, and proprioception. These force-sensing processes are critically dependent on the mechanical properties of tissues, which are often determined by the extracellular matrix (ECM). Tissues exhibit complex mechanical behaviors, including viscoelasticity, nonlinear elasticity, and mechanical plasticity. The molecular mechanisms of these properties remain poorly understood. Here, we demonstrate that in Drosophila larvae, the tissue-specific ECM protein pericardin (Prc) plays a central role in governing the mechanics of the proprioceptory lateral pentascolopidial organs (lch5). We show that Prc nonlinear elastic response acts like an end stop, enabling strain stiffening up to 400% without rupture, while also maintaining substantial prestrain. Prc-null organs tolerate only about 200% extension without damage and lack prestrain. Repeated application of mechanical load leads to progressive softening. The tension–strain relationship followed an exponential relation with a consistent strain threshold for the onset of nonlinearity, a characteristic feature of collagenous systems. These findings identify Prc as a critical molecular determinant of nonlinear elastic behavior in a mechanosensory organ and provide new insight into how ECM mechanical properties regulate tissue function.