[
International Worm Meeting,
2013]
Automated microfluidic platforms are enabling high-resolution and high-content bioassays on small animal models. An upstream device that automatically delivers different animal populations to these bioassay platforms could enhance high-throughput biological studies. Current population delivery strategies rely on suction from conventional well plates through tubing exposed to air, which causes certain drawbacks: 1) bubble and debris introduction to the sample, which interferes with analysis in downstream systems, 2) experimental throughput reduction due to added cleaning steps, and 3) the requirement for complex mechanical manipulations of well plate position. To address these concerns, we developed a microfluidic platform that can deliver multiple distinct animal populations from on-chip wells through a multiplexed valve system and used it to deliver C. elegans worms. This Population Delivery Chip can operate autonomously as part of a relatively simple experimental setup that does not require any of the major mechanical moving parts typical of plate-handling systems to address a given well. The autonomous device setup could serially deliver 16 distinct worm populations from on-chip wells out of a single outlet without introducing any bubbles or debris, damaging the animals, or population cross-contamination. The device achieved delivery of more than 90 % of the population preloaded into a given well in 4.7 seconds; an order of magnitude faster than current worm delivery methods. This platform could potentially handle similarly sized model organisms, such as zebrafish and drosophila larvae or cellular micro-colonies. This proof-of-principle implementation with 16 wells can be easily expanded in future devices with many more built-in wells to process additional populations.
Beron, Celia, Khalil, Moe, Bainbridge, Chance, Boutz, Daniel, Rickert, Trevor, Gokce, Sertan, Ghoashian, Navid, Ward, Kristi, Marcotte, Edward, Pierce-Shimomura, Jonathan, Papoulas, Ophelia, Ben-Yakar, Adela, Vidal-Gadea, Andres
[
International Worm Meeting,
2015]
A wide range of organisms use the earth's magnetic field to orient. Much of our understanding about the molecular basis for this behavior comes from work on magnetotactic bacteria. These organisms build nanometer-sized "compasses" from magnetic iron extracted from their environment. Evidence of similar biological magnetite has been reported in many magnetotactic animals (including C. elegans). It remains unclear if and how animals may use these "biological compasses" in this exciting form of sensory transduction. We have recently found that C. elegans readily orients to the magnetic field of the earth in a way that is consistent with a magnetite-based mechanism. Worms appear to use the magnetic field during vertical migrations using an identified a pair of sensory neurons. These neurons are required for magnetotaxis and respond cell-autonomously to earth-strength magnetic fields in calcium imaging experiments. We are attempting to identify the molecular machinery responsible for magnetotransduction using complementary biochemical, genetic and physiological approaches. To determine proteins associated with a hypothetical "worm compass", we performed mass spectrometry on iron particles isolated from C. elegans. Next, to determine whether these proteins are required for magnetotaxis, we assayed the magnetotactic ability of the corresponding mutants. For the subset of mutants that display defective magnetotaxis, we are analyzing the subcellular localization of their respective proteins near candidate compass structures. In parallel, we are testing the requirement of these genes in physiological responses to magnetic fields via calcium imaging. The genetic and behavioral tractability of C. elegans makes this a promising model for elucidating potentially conserved mechanisms by which many animals detect and orient to magnetic fields. .