We report a suite of key microfluidic devices for complex highthroughput whole-animal genetic and drug screens. We demonstrate a high-speed microfluidic sorter that can isolate and immobilize Caenorhabditis elegans in a well defined geometry for screening phenotypic features at subcellular resolution in physiologically active animals. We show an integrated chip containing individually addressable screening-chamber devices for incubation and exposure of individual animals to biochemical compounds and high-resolution time-lapse imaging of many animals on a single chip without the need for anesthesia. We describe a design for delivery of compound libraries in standard multiwell plates to microfluidic devices and also for rapid dispensing of screened animals into multiwell plates. When used in various combinations, these devices will facilitate a variety of high-throughput assays using whole animals, including mutagenesis and RNAi and drug screens at subcellular resolution, as well as high-throughput high-precision manipulations such as femtosecond laser microsurgery for large-scale in vivo neural degeneration and regeneration studies.Caenorhabditis elegans ͉ femtosecond laser microsurgery ͉ immobilization and time-lapse imaging ͉ mutagenesis ͉ RNAi and drug screening E xisting large vertebrate animal models currently cannot be used in high-throughput assays for rapid identification of new genes and drug targets because of the size and complexity of the instrumentation with which these models are studied. In recent years, the advantages of using small invertebrate animals as model systems for human disease have become increasingly apparent and have resulted in two Nobel Prizes in physiology and medicine during the last five years for studies conducted on the nematode Caenorhabditis elegans. The availability of a wide array of species-specific genetic techniques, along with the transparency of the worm and its ability to grow in minute volumes make C. elegans an extremely powerful model organism.However, since the first studies on C. elegans in the early 1960s, little has changed in how scientists manipulate this tiny organism by manually picking, sorting, and transferring individual animals. As a result, large-scale assays such as mutagenesis and RNAi screens (1-3) can take months or even years to complete manually. Currently, high-throughput C. elegans assays are performed by adapting techniques developed for screening cell lines, such as flow-through sorters and microplate readers (4-6). Because of the significant limitations of these methods, highthroughput small-animal studies either have to be dramatically simplified before they can be automated or cannot be conducted at all.Here, we report key components of an integrated, wholeanimal, high-throughput sorting and large-scale screening platform for drug and genetic assays with subcellular resolution using microfluidic devices. Although microfluidics have previously been used to perform novel assays on C. elegans, so far research has been limited to specific appl...

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