The early bird catches the worm: new technologies for the Caenorhabditis elegans toolkit

The nematode worm Caenorhabitis elegans is ideal as a model organism for scientific research owing to its simplicity and arsenal of available tools. New technologies increase the usefulness of the worm as a model.Loss-of-function experiments used to rely on untargeted mutagenesis techniques, such as chemical or transposon-based mutagenesis. Recent techniques allow for targeted mutagenesis using Mos-transposon-directed or zinc finger nuclease (ZFN)- or transcription activator-like effector nuclease (TALEN)-site-directed mutagenesis.Loss-of-function experiments using RNAi have been refined so that knockdown only occurs in a tissue of interest rather than in the whole body.Gain-of-function experiments have been improved in multiple facets by recent developments: recombineering technology and a fosmid DNA library have facilitated the generation and modification of DNA constructions, Mos transposition has allowed for single-copy insertion of a transgene into a defined locus, and using antibiotics as a selection marker has made it easier to screen for positive transgenesis events.Gain-of-function experiments have been enhanced by the introduction of the FLP–FRT (flippase and flippase recognition target) system for inducible gene expression. In combination with other inducible systems, such as Cre–loxP and the heat shock promoter, FLP–FRT should allow for more refined control over gene expression.Flow-cytometry technology can be used to ameliorate difficult or labour-intensive processes, including sorting synchronous-stage embryos and screening for genetic mutants.Microfluidic technology can semi-automate procedures that require considerable labour or precision. Recent developments use microfluidic setups in order to semi-automate lifespan analysis and neurosurgery.Imaging techniques have allowed for studies on the level of single cells or single molecules. Recent developments include methods to quantify gene expression in single cells, trace expression through cellular lineages during embryogenesis and detect single mRNA molecules in single cells.Optogenetics, a method that uses light to activate or inactivate specific neurons, is ideally suited for C. elegans owing to the worm's transparent body and fairly simple nervous system of only 302 neurons. Recent methods that allow for optogenetics in freely moving worms permit the examination of the neural networks underlying movement and other behaviours, which could not be examined in immobilized worms.