Microfluidic device for analysis of gas-evoked neuronal sensing in C. elegans

It is a challenging task to realize gaseous stimulations on Caenorhabibditis elegans for in vivo neuronal analysis of chemo-sensing, due to the difficulties in gas control and worm manipulation. Here, we demonstrated an integrated microfluidic system that could accurately deliver the gaseous stimuli to the worms' noses and track the in vivo neuronal activities simultaneously. The microfluidic chip consisted of a comb shaped micro-valve for worm immobilization and a T-junction structure for precise gas delivery. Neuronal responses of C. elegans to polar and non-polar gases were both investigated. The microfluidic device clearly demonstrated that oxygen with increasing levels of 0-10% and 0-21% induced URX neuronal responses. BAG neuronal activities were inhibited by carbon dioxide, showing the symptom of anesthesia. The vapor of polar odorant 1-octonal evoked significant calcium transients in ASH neurons in the wild-type animals but weak signals in tph-1 and Ce-grk-2 mutants. These results indicated that the developed device could be useful to identify various odor-evoked neuronal activities. (C) 2014 Elsevier B.V. All rights reserved.