WormScan: A Technique for High-Throughput Phenotypic Analysis of Caenorhabditis elegans

Abstract

BackgroundThere are four main phenotypes that are assessed in whole organism studies of Caenorhabditis elegans; mortality, movement, fecundity and size. Procedures have been developed that focus on the digital analysis of some, but not all of these phenotypes and may be limited by expense and limited throughput. We have developed WormScan, an automated image acquisition system that allows quantitative analysis of each of these four phenotypes on standard NGM plates seeded with E. coli. This system is very easy to implement and has the capacity to be used in high-throughput analysis.Methodology/Principal FindingsOur system employs a readily available consumer grade flatbed scanner. The method uses light stimulus from the scanner rather than physical stimulus to induce movement. With two sequential scans it is possible to quantify the induced phototactic response. To demonstrate the utility of the method, we measured the phenotypic response of C. elegans to phosphine gas exposure. We found that stimulation of movement by the light of the scanner was equivalent to physical stimulation for the determination of mortality. WormScan also provided a quantitative assessment of health for the survivors. Habituation from light stimulation of continuous scans was similar to habituation caused by physical stimulus.Conclusions/SignificanceThere are existing systems for the automated phenotypic data collection of C. elegans. The specific advantages of our method over existing systems are high-throughput assessment of a greater range of phenotypic endpoints including determination of mortality and quantification of the mobility of survivors. Our system is also inexpensive and very easy to implement. Even though we have focused on demonstrating the usefulness of WormScan in toxicology, it can be used in a wide range of additional C. elegans studies including lifespan determination, development, pathology and behavior. Moreover, we have even adapted the method to study other species of similar dimensions.

C. elegans in high-throughput drug discovery

“…An economical alternative to expensive automated microscope-based screening platforms is WormScan [67]. WormScan uses a standard flatbed scanner to monitor C. elegans movement.…”

Developing high-throughput methods for C. elegans to better understand the newly discovered gasotransmitter sulfur dioxide

“…This screen identified RPO21, the closest homologue of the C. elegans F08F8.9 gene, as a major protein target of SO 2 . Thus, F08F8.9 was identified as a SO 2 resistance factor in the forward genetic and confirmed in the model organism C. elegans and identified in chemical genomic screen in S. cerevisiae. This supports a role for RNA polymerase II subunit in SO 2 resistance.…”

“…Sulfur dioxide was dispensed as pure gas from a high pressure cylinder (BOC Ltd) into a FlexFoil PLUS gas sample bag (Air-Met Scientific Pty Ltd), from which it was withdrawn with a gas tight syringe and injected into glass desiccators as previously described [2]. Alternatively, SO 2 was generated in situ by incorporating the SO 2 donor, sodium metabisulfite, into liquid NGM.…”

“…The initial genetic screen was confined to 10 strains for resistance phenotype testing (Table 2). These strains were analyzed using a modification to the WormScan technique described in Chapter 2, to increase throughput [2]. The modification was to undertake mortality testing in standard liquid NGM in 96-well plates.…”

Metabolic study of Alzheimer’s disease using mutant C. elegans

“…The resulting L1 larvae were shifted to the fresh NGM agar plates seeded with E. coli to initiate growth. Aβ inducible transgenic worms were initially cultivated at Phenotypes of the worms were monitored by visual observation under a microscope or quantified using the WormScan procedure [415].…”