Microfluidic chamber arrays for whole-organism behavior-based chemical screening

Abstract

The nematode Caenorhabditis elegans is an important model organism in genetic research and drug screening because of its relative simplicity, ease of maintenance, amenability to simple genetic manipulation, and relevance to human biology. However, their small size and mobility make nematodes difficult to physically manipulate, particularly with spatial and temporal precision. We have developed a microfluidic device to overcome these challenges and enable fast behavior-based chemical screening in C. elegans. The key components of this easy-to-use device allow rapid loading and housing of C. elegans in a chamber array for chemical screening. A simple two-step loading process enables simultaneous loading of a large number of animals within a few minutes without using any expensive/active off-chip components. In addition, chemicals can be precisely delivered to the worms and exchanged with high temporal precision. To demonstrate this feature and the ability to measure time dependent responses to chemicals, we characterize the transient response of worms exposed to different concentrations of anesthetics. We then use the device to study the effect of chemical signals from hermaphrodite worms on male behavior. The ability of the device to maintain a large number of free moving animals in one field of view over a long period of time permits us to demonstrate an increase in the incidence of a specific behavior in males subjected to worm-conditioned medium. Because our device allows monitoring of a large number of worms with single-animal resolution, we envision that this platform will greatly expedite chemical screening in C. elegans.

A size threshold governsCaenorhabditis elegansdevelopmental progression

“…Worm growth has also been studied using an array of chambers in which L4 worms were individually loaded to monitor development to adulthood [26], or using a device developed to observe collections of 30-40 adults worms [27]. A device with multiple observation chambers for adult worms was exploited to study chemical effects on worm behaviour [28] and oil-inwater emulsions were used to encapsulate individual worm embryos [29,30] or L1s [31] which could develop to adulthood. While encapsulation allows the study of even early larval stages which are otherwise challenging, proper feeding and the physiological effect of surfactant required for droplet production limit the applicability of this method [32].…”

Small-Volume Analysis of Cell–Cell Signaling Molecules in the Brain

“…Another microfluidic device combined with in vivo optical neurophysiology has been used to study proprioceptive properties in the worm motor circuit (Wen et al, 2012). A simpler combination of a microfluidic system with optical microscopy allowed monitoring of the male response to hermaphrodite-conditioned medium containing mating signals (Chung et al, 2011).…”

A microfluidic device for automated, high-speed microinjection of Caenorhabditis elegans

“…[29][30][31][32][33][34][35][36][37][38][39][40][41] Several microfluidic devices have been reported for immobilizing worms in enclosed channels; 29,37,39,42 however, they do not allow a micropipette to access the worm body for injection. Two microfluidic devices have been developed to facilitate manual C. elegans microinjection.…”