Piezo controlled microinjection: an in vivo complement for in vitro sensory studies in insects

Recent insights into insect olfactory signaling based on in vitro analyses have created an urgent need for equivalent in vivo analyses using living organisms. Here, we present a microinjection system that establishes a "virtual petri dish" within sensory structures for the application of agents to sensory neurons. Our system uses a series of pumps to inject chemical agents via air pressure into the surrounding lymph. We show using tetrodotoxin and forskolin application that robust effects on response dynamics of Drosophila melanogaster olfactory sensory neurons could be observed within 200 s, and suggest data analysis techniques to improve estimation of pharmacological effects on response kinetics. This approach provides an improved in vivo method to investigate questions in sensory neuron physiology as a complement to heterologous expression systems.