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

Abstract

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 4s by laser. Nevertheless, the immobilized C. elegans was able to resume its full locomotion in 1s after the laser was removed. Our results suggested not continuously exposing worms to the hydrogel environment more than 4h. Comparisons of a control group and worms treated with the optoelectric condition for 1h 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.