In collaboration with Georg Nagel and Ernst Bamberg (Würzburg University and Max Planck Institute for Biophysics), we have established a directly light-gated cation channel, channelrhodopsin-2 (ChR2), from a green alga, as a tool to evoke activity in muscles and neurons of C. elegans, simply by illumination with blue light. This allows to trigger neuronal activity in an essentially non-invasive manner in live and behaving animals. Thus, we could cause simultaneous contraction of all body muscles in response to light. When expressed in mechanosensory neurons, ChR2 could evoke (reversal) responses, as if the animals had been touched. This was even possible in animals that bear a mutation of the mechanosensory ion-channel and thus lack normal activity of these cells. The activity of ChR2 in situ could also be shown by direct electrophysiology of C. elegans muscle. This work has recently been published: Nagel et al., 2005, Curr. Biol. 15, 2279-2284. Recently, we also introduced the yellow-light driven chloride pump Halorhodopsin from the Archaeon Natronomonas pharaonis (NpHR), as a photo-hyperpolarizing agent, to acutely inhibit neurons and muscles. NpHR can be combined with ChR2 to allow acute, bidirectional control of neurons using yellow and blue light. This work was performed in collaboration with Karl Deisseroth’s lab in Stanford (USA): Zhang et al. (2007) Nature 446: 633-39

Collaborations: Georg Nagel, Würzburg University and Ernst Bamberg, Max Planck Institute for Biophysics; Karl Deisseroth, Stanford University, USA