Rapid, reversible and addressable immobilization of Caenorhabditis elegans in Pluronic F-127 using an optoelectric device

Caenorhabditis elegans is a simple model animal in genetic engineering, neural science, and developmental biology. Worm immobilization is an essential step in many operations, such as microsurgeries and long-term imaging. To this end, an immobilization technique based on the combined use of an optoelectric device and a thermos-reversible hydrogel, Pluronic F-127, was developed in this study. The optoelectric device was coated with a photoconductive layer, allowing local circuit channels to be switched by light. Optimal conditions were investigated. A transgenic strain, TJ356, showed that the stress response under the optoelectric condition was negligible. The hydrogel solution sandwiched in the device achieved gelation within 4 s by laser. Nevertheless, the immobilized C. elegans was able to resume its full locomotion in 1 s after the laser was removed. Our results suggested not continuously exposing worms to the hydrogel environment more than 4 h. Comparisons of a control group and worms treated with the optoelectric condition for 1 h daily indicated that no statistical differences (p > 0.05) between the two groups in number of progeny, body length, and lifespan. The technique was eventually used to visualize the senescence process of the RW1596 strain. A serial sarcomere images from the same batch of worms acquired at different developmental stages showed progressive muscle deterioration during aging. This rapid and reversible immobilization technique provides insight to worm-based applications that require long-term and constant monitoring, such as drug assays.