Quantitative Investigation Of C.elegans Chemotaxis Using A Microfluidic Device

Caenorhabditis elegans (C. elegans) directs its movements in response to externalenvironmental changes such as salt concentrations. To investigate the chemotacticbehavior of C. elegans, traditional methods involve chemotaxis assays on agar plates.However, it is difficult to precisely control the slope of linear gradients, and the gradient isconducted by diffusing of chemoeffector, which is rather time-consuming, and can’t bedefinded quantitatively. Here, we developed a flow-based microfluidic device to achievethis gool, using laminar flow and diffusional mixing. Compared with traditional methods,microfluidic methods have their unique advantages: flexible design of microchannel, rapiddiffusing for gradient establishing, easily controlling of the flow. What is more,experimental conditions are reproducible and identical.Using our micro-device, it was concluded that worms prefer low concentration ofNaCl to high concentration, while showed repellent with the concentration lower than20mM. Further studies about VC513grk-2（gk268）, a mutation strain lacking of GRK-2function, demonstrated that the chemotactic response of C. elegans to low concentrationof NaCl was reduced, and the repellent response to low concentration also decreased.What’s more, the analysis of the behaviour of not fully developed worms suggestedworms also had the perfect nervous system to control the chemotactic behaviour. Theseresults suggest that the device not only has unique advantage in quantitative study ofC.elegans chemotactic behaviour, but also has a potential application on the neurons’function identification.