@article{LiPradaDaminelietal.2021,
  author    = {Li, Kunkun and Prada, Juan and Damineli, Daniel S. C. and Liese, Anja and Romeis, Tina and Dandekar, Thomas and Feij{\´o}, Jos{\´e} A. and Hedrich, Rainer and Konrad, Kai Robert},
  title     = {An optimized genetically encoded dual reporter for simultaneous ratio imaging of Ca\(^{2+}\) and H\(^{+}\) reveals new insights into ion signaling in plants},
  series = {New Phytologist},
  volume    = {230},
  journal   = {New Phytologist},
  number    = {6},
  doi       = {10.1111/nph.17202},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-239847},
  pages     = {2292 -- 2310},
  year      = {2021},
  abstract  = {Whereas the role of calcium ions (Ca\(^{2+}\)) in plant signaling is well studied, the physiological significance of pH-changes remains largely undefined. Here we developed CapHensor, an optimized dual-reporter for simultaneous Ca\(^{2+}\) and pH ratio-imaging and studied signaling events in pollen tubes (PTs), guard cells (GCs), and mesophyll cells (MCs). Monitoring spatio-temporal relationships between membrane voltage, Ca\(^{2+}\)- and pH-dynamics revealed interconnections previously not described. In tobacco PTs, we demonstrated Ca\(^{2+}\)-dynamics lag behind pH-dynamics during oscillatory growth, and pH correlates more with growth than Ca\(^{2+}\). In GCs, we demonstrated abscisic acid (ABA) to initiate stomatal closure via rapid cytosolic alkalization followed by Ca2+ elevation. Preventing the alkalization blocked GC ABA-responses and even opened stomata in the presence of ABA, disclosing an important pH-dependent GC signaling node. In MCs, a flg22-induced membrane depolarization preceded Ca2+-increases and cytosolic acidification by c. 2 min, suggesting a Ca\(^{2+}\)/pH-independent early pathogen signaling step. Imaging Ca2+ and pH resolved similar cytosol and nuclear signals and demonstrated flg22, but not ABA and hydrogen peroxide to initiate rapid membrane voltage-, Ca\(^{2+}\)- and pH-responses. We propose close interrelation in Ca\(^{2+}\)- and pH-signaling that is cell type- and stimulus-specific and the pH having crucial roles in regulating PT growth and stomata movement.},
  language  = {en}
}
@article{BeckYuStrzelczykPaulsetal.2018,
  author    = {Beck, Sebastian and Yu-Strzelczyk, Jing and Pauls, Dennis and Constantin, Oana M. and Gee, Christine E. and Ehmann, Nadine and Kittel, Robert J. and Nagel, Georg and Gao, Shiqiang},
  title     = {Synthetic light-activated ion channels for optogenetic activation and inhibition},
  series = {Frontiers in Neuroscience},
  volume    = {12},
  journal   = {Frontiers in Neuroscience},
  number    = {643},
  doi       = {10.3389/fnins.2018.00643},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-177520},
  year      = {2018},
  abstract  = {Optogenetic manipulation of cells or living organisms became widely used in neuroscience following the introduction of the light-gated ion channel channelrhodopsin-2 (ChR2). ChR2 is a non-selective cation channel, ideally suited to depolarize and evoke action potentials in neurons. However, its calcium (Ca2\(^{2+}\)) permeability and single channel conductance are low and for some applications longer-lasting increases in intracellular Ca\(^{2+}\) might be desirable. Moreover, there is need for an efficient light-gated potassium (K\(^{+}\)) channel that can rapidly inhibit spiking in targeted neurons. Considering the importance of Ca\(^{2+}\) and K\(^{+}\) in cell physiology, light-activated Ca\(^{2+}\)-permeant and K\(^{+}\)-specific channels would be welcome additions to the optogenetic toolbox. Here we describe the engineering of novel light-gated Ca\(^{2+}\)-permeant and K\(^{+}\)-specific channels by fusing a bacterial photoactivated adenylyl cyclase to cyclic nucleotide-gated channels with high permeability for Ca\(^{2+}\) or for K\(^{+}\), respectively. Optimized fusion constructs showed strong light-gated conductance in Xenopus laevis oocytes and in rat hippocampal neurons. These constructs could also be used to control the motility of Drosophila melanogaster larvae, when expressed in motoneurons. Illumination led to body contraction when motoneurons expressed the light-sensitive Ca\(^{2+}\)-permeant channel, and to body extension when expressing the light-sensitive K\(^{+}\) channel, both effectively and reversibly paralyzing the larvae. Further optimization of these constructs will be required for application in adult flies since both constructs led to eclosion failure when expressed in motoneurons.},
  language  = {en}
}