title: Dual Color Neural Activation and Behavior Control with Chrimson and CoChR in Caenorhabditis elegans.
abstract: By enabling a tight control of cell excitation, optogenetics is a powerful approach to study the function of neurons and neural circuits. With its transparent body, a fully mapped nervous system, easily quantifiable behaviors and many available genetic tools, Caenorhabditis elegans is an extremely well-suited model to decipher the functioning logic of the nervous system with optogenetics. Our goal was to establish an efficient dual color optogenetic system for the independent excitation of different neurons in C. elegans. We combined two recently discovered channelrhodopsins: the red-light sensitive Chrimson from Chlamydomonas noctigama and the blue-light sensitive CoChR from Chloromonas oogama. Codon-optimized versions of Chrimson and CoChR were designed for C. elegans and expressed in different mechanosensory neurons. Freely moving animals produced robust behavioral responses to light stimuli of specific wavelengths. Since CoChR was five times more sensitive to blue light than the commonly used ChR2, we were able to use low blue light intensities producing no cross-activation of Chrimson. Thanks to these optogenetics tools, we revealed asymmetric cross-habituation effects between the gentle and harsh touch sensory motor pathways. Collectively, our results establish the Chrimson/CoChR pair as a potent tool for bimodal neural excitation in C. elegans and equip this genetic model organism for the next generation of in vivo optogenetic analyses.
authors.affiliation: Department of Biology, University of Fribourg, CH-1700 Fribourg, Switzerland.
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Schild
authors.affiliation: Department of Biology, University of Fribourg, CH-1700 Fribourg, Switzerland dominique.glauser@unifr.ch.
authors.forename: Dominique A
authors.initials: DA
authors.lastname: Glauser
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000528:radiation effects; D032763:Behavior Control / Q000379:methods*; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000528:radiation effects*; D002696:Chlamydomonas / Q000235:genetics; D003116:Color; D006185:Habituation, Psychophysiologic / Q000235:genetics / Q000528:radiation effects; D008027:Light; D009474:Neurons / Q000378:metabolism / Q000528:radiation effects*; D009619:Nociceptors / Q000378:metabolism / Q000528:radiation effects; D062308:Optogenetics / Q000379:methods*; D010940:Plant Proteins / Q000235:genetics*; D012243:Rhodopsin / Q000235:genetics*; D055698:Touch Perception / Q000235:genetics / Q000528:radiation effects
chemical_list: D010940:Plant Proteins; D012243:Rhodopsin
keywords: avoidance; behavior; mechanoreceptor; optogenetics