Background: Light-driven proton pumps are utilized to control the neural activity. Results: We have succeeded to produce a blue-shifted proton pump. The rotation of the ␤-ionone ring contributes to the spectral shift. Conclusion: The designed color variant provides a tool that allows the control of neural activity by blue light. Significance: The knowledge will help to understand the color-tuning mechanism and can be utilized for optogenetics.

BackgroundOptogenetic techniques using light-driven ion channels or ion pumps for controlling excitable cells have greatly facilitated the investigation of nervous systems in vivo. A model organism, C. elegans, with its small transparent body and well-characterized neural circuits, is especially suitable for optogenetic analyses.Methodology/Principal FindingsWe describe the application of archaerhodopsin-3 (Arch), a recently reported optical neuronal silencer, to C. elegans. Arch::GFP expressed either in all neurons or body wall muscles of the entire body by means of transgenes were localized, at least partially, to the cell membrane without adverse effects, and caused locomotory paralysis of worms when illuminated by green light (550 nm). Pan-neuronal expression of Arch endowed worms with quick and sustained responsiveness to such light. Worms reliably responded to repeated periods of illumination and non-illumination, and remained paralyzed under continuous illumination for 30 seconds. Worms expressing Arch in different subsets of motor neurons exhibited distinct defects in the locomotory behavior under green light: selective silencing of A-type motor neurons affected backward movement while silencing of B-type motor neurons affected forward movement more severely. Our experiments using a heat-shock-mediated induction system also indicate that Arch becomes fully functional only 12 hours after induction and remains functional for more than 24 hour.Conclusions/SgnificanceArch can be used for silencing neurons and muscles, and may be a useful alternative to currently widely used halorhodopsin (NpHR) in optogenetic studies of C. elegans.

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In this paper, we compare and summarize the features of two types of two-dimensional array illuminators -the binary zone plate array and the Talbot array illuminator -both producing a spot array in the near field without the addition of any optical component. Numerical evaluations of the illumination efficiency are based on the scalar theory. We present and discuss furthermore the experimental results obtained by such array illuminators when fabricated under the same conditions, i.e., by optical lithography and two masks (four-level binary optics).