Hydrogel-droplet microfluidic platform for high-resolution imaging and sorting of early larval Caenorhabditis elegans

Abstract

The nematode Caenorhabditis elegans is an important model organism in research on neuroscience and development because of its stereotyped anatomy, relevance to human biology, and ease of culture and genetic manipulation. The first larval stage (L1) is of particular interest in many biological problems, including post-embryonic developmental processes and developmental decision-making, such as dauer formation. However, L1’s small size and high mobility make it difficult to manipulate; particularly in microfluidic chips, which have been used to great advantage in handling larger larvae and adult animals, small features are difficult to fabricate and these structures often get clogged easily, making the devices less robust. We have developed a microfluidic device to overcome these challenges and enable high-resolution imaging and sorting of early larval stage C. elegans via encapsulation in droplets of a thermosensitive hydrogel. To achieve precise handling of early larval stage worms, we demonstrated on-chip production, storage, and sorting of hydrogel droplets. We also demonstrated temporary immobilization of the worms within the droplets, allowing high-resolution imaging with minimal physiological perturbations. Because of the ability to array hydrogel droplets for handling a large number of L1 worms in a robust way, we envision that this platform will be widely applicable to screening in various developmental studies.

High-throughput screening in the C. elegans nervous system

“…Instead, animals in PF127 solution are placed on a photo-absorbing layer, and triggering gelation is achieved by tuning the intensity of a halogen lamp directed at the sample [Hwang et al, 2014]. PF127 has also been successfully incorporated into a droplet-based microfluidic device that generates up to 250 microdroplets of PF127 containing individual L1 larvae [Aubry et al, 2015]. Upon sol-gel transition, motion is sufficiently reduced for imaging of individual neurons under high-magnification objectives.…”

Droplet Microfluidics as a Tool for the Generation of Granular Matters and Functional Emulsions

“…Here, we will mention just a few of the important achievements of droplet research in these fields: i) digitized diagnostic assays (Hindson et al, 2011;Rissin et al, 2010;Tang and Shum, 2016); ii) directed evolution towards the improvement of the catalytic functions of enzymes and microorganisms Levin and Aharoni, 2012;Zinchenko et al, 2014); iii) determination of optimum conditions for protein crystallization (Yamaguchi et al, 2013;Zheng et al, 2003;Zhu and Fang, 2013); iv) new experimental approaches useful in the next-generation sequencing of cell genomes (Ma et al, 2017;Macosko et al, 2015;Zhang K. et al, 2016); and v) analysis of larger model organisms such as C. elegans (Aubry et al, 2015).…”

Microfluidic Platform for Analyzing the Thermotaxis of C. elegans in a Linear Temperature Gradient

“…Thus microfluidic systems are used as a platform for various studies with C. elegans. [20][21][22][23][24][25][26][27][28] McCormick et al demonstrated a microfluidic device for analysis of C. elegans orientation. 29 They designed the device in order to immobilize C. elegans and only allow the movement of the head of C. elegans.…”