title: Channelrhodopsin-2-XXL, a powerful optogenetic tool for low-light applications.
abstract: Channelrhodopsin-2 (ChR2) has provided a breakthrough for the optogenetic control of neuronal activity. In adult Drosophila melanogaster, however, its applications are severely constrained. This limitation in a powerful model system has curtailed unfolding the full potential of ChR2 for behavioral neuroscience. Here, we describe the D156C mutant, termed ChR2-XXL (extra high expression and long open state), which displays increased expression, improved subcellular localization, elevated retinal affinity, an extended open-state lifetime, and photocurrent amplitudes greatly exceeding those of all heretofore published ChR variants. As a result, neuronal activity could be efficiently evoked with ambient light and even without retinal supplementation. We validated the benefits of the variant in intact flies by eliciting simple and complex behaviors. We demonstrate efficient and prolonged photostimulation of monosynaptic transmission at the neuromuscular junction and reliable activation of a gustatory reflex pathway. Innate male courtship was triggered in male and female flies, and olfactory memories were written through light-induced associative training.
authors.affiliation: Department of Neurophysiology, Institute of Physiology, Julius-Maximilians-University of Würzburg, D-97070 Würzburg, Germany;
authors.forename: Alexej
authors.initials: A
authors.lastname: Dawydow
authors.affiliation: Institute for Molecular Plant Physiology and Biophysics, Biocenter, Julius-Maximilians-University of Würzburg, D-97082 Würzburg, Germany; and.
authors.forename: Ronnie
authors.initials: R
authors.lastname: Gueta
authors.affiliation: Department of Neurophysiology, Institute of Physiology, Julius-Maximilians-University of Würzburg, D-97070 Würzburg, Germany;
authors.forename: Dmitrij
authors.initials: D
authors.lastname: Ljaschenko
authors.affiliation: Institute for Molecular Plant Physiology and Biophysics, Biocenter, Julius-Maximilians-University of Würzburg, D-97082 Würzburg, Germany; and.
authors.forename: Sybille
authors.initials: S
authors.lastname: Ullrich
authors.affiliation: Department of Molecular Neurobiology of Behaviour, Georg-August-University of Göttingen, D-37077 Göttingen, Germany.
authors.forename: Moritz
authors.initials: M
authors.lastname: Hermann
authors.affiliation: Department of Neurophysiology, Institute of Physiology, Julius-Maximilians-University of Würzburg, D-97070 Würzburg, Germany;
authors.forename: Nadine
authors.initials: N
authors.lastname: Ehmann
authors.affiliation: Institute for Molecular Plant Physiology and Biophysics, Biocenter, Julius-Maximilians-University of Würzburg, D-97082 Würzburg, Germany; and.
authors.forename: Shiqiang
authors.initials: S
authors.lastname: Gao
authors.affiliation: Department of Molecular Neurobiology of Behaviour, Georg-August-University of Göttingen, D-37077 Göttingen, Germany.
authors.forename: André
authors.initials: A
authors.lastname: Fiala
authors.affiliation: Department of Neurophysiology, Institute of Physiology, Julius-Maximilians-University of Würzburg, D-97070 Würzburg, Germany;
authors.forename: Tobias
authors.initials: T
authors.lastname: Langenhan
authors.affiliation: Institute for Molecular Plant Physiology and Biophysics, Biocenter, Julius-Maximilians-University of Würzburg, D-97082 Würzburg, Germany; and robert.kittel@uni-wuerzburg.de nagel@uni-wuerzburg.de.
authors.forename: Georg
authors.initials: G
authors.lastname: Nagel
authors.affiliation: Department of Neurophysiology, Institute of Physiology, Julius-Maximilians-University of Würzburg, D-97070 Würzburg, Germany; robert.kittel@uni-wuerzburg.de nagel@uni-wuerzburg.de.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Kittel
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D005074:Evoked Potentials, Visual; D005260:Female; D008297:Male; D020125:Mutation, Missense; D009474:Neurons / Q000378:metabolism*; D012243:Rhodopsin / Q000235:genetics / Q000378:metabolism*; D009435:Synaptic Transmission
chemical_list: D012243:Rhodopsin