Micromanipulation of C. elegans for Force-Displacement Experiments

For larger amplitude force-displacement experiments we used an in-house customized micromanipulation setup to allow uniaxial indentation of C. elegans with a microforce sensing probe (Elmi et al., 2017 (link)). Treated animals were mounted on a 2% agarose pad on top of a microscope slide (Figure 3B). To prevent motion during indentation, animals were glued (Dermabond glue, Suturonline.com) on the side to the edge of a coverslip fixed on top of the agarose pad before immersion in M9 buffer. The sample imaged using an upright widefield fluorescence microscope (BX51WI, Olympus) with 20x/1.0 water immersion objective lens (LUMPlanFL N, Olympus) fluorescence filter cube (Semrock) and a sCMOS camera (Orca-Flash4.0 v2, Hamamatsu Photonics). The body of each animal was indented using a microforce sensing probe (FT-S100, FemtoTools) fitted with a tungsten tip. The position of the probe was controlled using a motorized 4-axis stage system (ECS series, Attocube), which allowed precise positioning of the tip within (x, z) and perpendicular (y) to the focal plane of the microscope, as well as adjustment of the in-plane tilt. Animals were mounted on a separate kinematic stage system decoupled from the microscope body and the probe.