Mechanoreceptors of the cell membrane: bead adhesion and tether pulling assays.

This application example is taken from a work from the Neurophotonics and Mechanical Systems Biology Lab at the Institute of Photonic Sciences (ICFO). In this work, the authors investigated the mechanics, molecules and neurons responsible for proprioception in Caenorhabditis (C.) elegans to gain insight into how mechanosensation shapes the orbital trajectory to a well-defined limit cycle. The authors found that found that proprioceptors (sensory mechanoreceptors that respond to movements and position of the body) were activated under compressive stresses in both vivo and in vitro experiments.

For the experiments in vitro, the authors used SENSOCELL to optically trap microspheres and extrude membrane tethers from isolated DVA neuron axons. For this purpose, the authors programmed their custom pulling routines with our LightAce software SDK to control the beads displacement and pulling velocity ranging from 5 to 80 μm/s for each subsequent tether pulling step (see more information on tether pulling routines here). In this way, they could apply positive and negative tension gradients to the isolated axons and simultaneously image the resultant Ca²⁺ ion channel activity using confocal microscopy.

From these experiments, the authors observed that the increment of Ca²⁺ signals preferentially occurred during the relaxation phase of the tether pulling force-distance curves, indicating that negative tension gradients can induce neuronal activity, similarly to the axon compression in vivo tests. 

Cell membrane adhesion dynamics can be studied with SENSOCELL optical tweezers in a direct and simple manner using automatized routines for trap motion (periodic oscillations or trajectories) while measuring adhesion forces in a direct and absolute way. Use functionalized beads with the molecules of interest and start deciphering the mechanisms of cell membrane adhesion of your sample cells with SENSOCELL!