title: Non-invasive manipulation of Drosophila behavior by two-photon excited red-activatable channelrhodopsin.
abstract: Scattering and absorption limit light penetration through inhomogeneous tissue. To reduce scattering, biochemists have shifted the wavelengths of excitation light for optogenetic actuators and fluorescent proteins to the orange-red range, while physicists have developed multiphoton technologies for deep tissue stimulation. We have built a rapid multiphoton spectroscopic screening system of genetically encoded red-activatable channelrhodopsin (ReaChR), and considered specific behaviors in transgenic Drosophila melanogaster as readouts to optimize the laser parameters for two-photon optogenetic activation. A wavelength-tunable optical parametric amplifier was adopted as the major light source for widefield two-photon excitation (TPE) of ReaChR. Our assays suggest that the optimized TPE wavelength of ReaChR is 1250 nm. Exploiting its capacity for optogenetic manipulation to induce macroscopic behavioral change, we realized rapid spectroscopic screening of genetically encoded effectors or indicators in vivo, and used modulation of ReaChR in the fly as a successful demonstration of such a system.
authors.affiliation: Institute of Biotechnology, National Tsing Hua University, Hsinchu 30013, Taiwan ; These authors contributed equally to this work.
authors.forename: Po-Yen
authors.initials: PY
authors.lastname: Hsiao
authors.affiliation: Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30013, Taiwan ; These authors contributed equally to this work.
authors.forename: Chia-Lun
authors.initials: CL
authors.lastname: Tsai
authors.affiliation: Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30013, Taiwan ; Department of Electrical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Ming-Chang
authors.initials: MC
authors.lastname: Chen
authors.affiliation: Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30013, Taiwan ; Brain Research Center, National Tsing Hua University, Hsinchu 30013, Taiwan ; Department of Electrical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Yen-Yin
authors.initials: YY
authors.lastname: Lin
authors.affiliation: Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30013, Taiwan ; Department of Electrical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan ; shangda@ee.nthu.edu.tw.
authors.forename: Shang-Da
authors.initials: SD
authors.lastname: Yang
authors.affiliation: Institute of Biotechnology, National Tsing Hua University, Hsinchu 30013, Taiwan ; Brain Research Center, National Tsing Hua University, Hsinchu 30013, Taiwan ; Kavli Institute for Brain and Mind, University of California, San Diego, La Jolla, CA 92093-0526, USA ; aschiang@life.nthu.edu.tw.
authors.forename: Ann-Shyn
authors.initials: AS
authors.lastname: Chiang
keywords: (000.1430) Biology and medicine; (190.4970) Parametric oscillators and amplifiers; (320.7110) Ultrafast nonlinear optics