On-demand optical immobilization of Caenorhabditis elegans for high-resolution imaging and microinjection.

This paper describes a novel selective immobilization technique based on optical control of the sol-gel transition of thermoreversible Pluronic gel, which provides a simple, versatile, and biocompatible approach for high-resolution imaging and microinjection of Caenorhabditis elegans.

C.L.I.P.--continuous live imaging platform for direct observation of C. elegans physiological processes.

Direct observation of developmental and physiological changes in certain model organisms over time has been technically challenging. In the model organism Caenorhabditis elegans, these studies require frequent or continuous imaging at physiologically benign conditions. However, standard methods use anaesthetics, glue, or microbeads, which prevent animals from feeding during the experiment. Thus, the animals' normal physiological function may be affected over time. Here we present a platform designed for dynamic studies of C. elegans. The system is capable of immobilizing only the animals' bodies under benign conditions and without physical deformation. Simultaneously, the animals' heads remain free to move and feed for the duration of the experiment. This allows for high-resolution and high-magnification fluorescent imaging of immobilized and feeding animals. The system is very easy to fabricate, set up, and operate, and should be widely applicable to many problems in developmental and physiological studies.

Long-term high-resolution imaging and culture of C. elegans in chip-gel hybrid microfluidic device for developmental studies.

Developmental studies in multicellular model organisms such as Caernohabditis elegans rely extensively on the ability to cultivate and image animals repeatedly at the cell or subcellular level. However, standard high-resolution imaging techniques require the use of anaesthetics for immobilization, and may have undesirable side effects on development. Thus such techniques are not ideal in allowing the same animals to grow and be imaged throughout development to observe specific developmental processes. In this paper, we present a microfluidic system designed to overcome these difficulties. The system allows for long-term culture of C. elegans starting at L1 larval stage and repeated high-resolution imaging at physiological temperatures without using anaesthetics. We use a commercially available biocompatible polymer, Pluronic F127 for immobilization; this polymer is capable of a reversible thermo-sensitive sol-gel transition within approximately 2 degrees C, which is well-controlled in the microfluidic chip. The gel phase is sufficient to immobilize the animals. While animals are not imaged, they are cultured in individual chambers in media containing nutrients required for development. We show here that this method facilitates time-lapse studies of single animals at high-resolution and lends itself to live imaging experiments on developmental processes and dynamic events.