@phdthesis{Ast2013,
  author    = {Ast, Cindy},
  title     = {Design and photophysical characterization of single fluorophore-based ammonium sensors},
  address   = {Potsdam},
  pages     = {90 S.},
  year      = {2013},
  language  = {en}
}
@article{DeMicheleAstLoqueetal.2013,
  author    = {De Michele, Roberto and Ast, Cindy and Loque, Dominique and Ho, Cheng-Hsun and Andrade, Susana L. A. and Lanquar, Viviane and Grossmann, Guido and Gehne, Soeren and Kumke, Michael Uwe and Frommer, Wolf B.},
  title     = {Fluorescent sensors reporting the activity of ammonium transceptors in live cells},
  series = {ELIFE},
  volume    = {2},
  journal   = {ELIFE},
  number    = {3},
  publisher = {ELIFE SCIENCES PUBLICATIONS LTD},
  address   = {CAMBRIDGE},
  issn      = {2050-084X},
  doi       = {10.7554/eLife.00800},
  pages     = {22},
  year      = {2013},
  abstract  = {Ammonium serves as key nitrogen source and metabolic intermediate, yet excess causes toxicity. Ammonium uptake is mediated by ammonium transporters, whose regulation is poorly understood. While transport can easily be characterized in heterologous systems, measuring transporter activity in vivo remains challenging. Here we developed a simple assay for monitoring activity in vivo by inserting circularly-permutated GFP into conformation-sensitive positions of two plant and one yeast ammonium transceptors (\’AmTrac and \’MepTrac\’). Addition of ammonium to yeast cells expressing the sensors triggered concentration dependent fluorescence intensity (FI) changes that strictly correlated with the activity of the transporter. Fluorescence-based activity sensors present a novel technology for monitoring the interaction of the transporters with their substrates, the activity of transporters and their regulation in vivo, which is particularly valuable in the context of analytes for which no radiotracers exist, as well as for cell-specific and subcellular transport processes that are otherwise difficult to track.},
  language  = {en}
}
@misc{AstSchmaelzlinLoehmannsroebenetal.2012,
  author    = {Ast, Cindy and Schm{\"a}lzlin, Elmar and L{\"o}hmannsr{\"o}ben, Hans-Gerd and van Dongen, Joost T.},
  title     = {Optical oxygen micro- and nanosensors for plant applications},
  series = {Sensors},
  volume    = {12},
  journal   = {Sensors},
  number    = {6},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1424-8220},
  doi       = {10.3390/s120607015},
  pages     = {7015 -- 7032},
  year      = {2012},
  abstract  = {Pioneered by Clark's microelectrode more than half a century ago, there has been substantial interest in developing new, miniaturized optical methods to detect molecular oxygen inside cells. While extensively used for animal tissue measurements, applications of intracellular optical oxygen biosensors are still scarce in plant science. A critical aspect is the strong autofluorescence of the green plant tissue that interferes with optical signals of commonly used oxygen probes. A recently developed dual-frequency phase modulation technique can overcome this limitation, offering new perspectives for plant research. This review gives an overview on the latest optical sensing techniques and methods based on phosphorescence quenching in diverse tissues and discusses the potential pitfalls for applications in plants. The most promising oxygen sensitive probes are reviewed plus different oxygen sensing structures ranging from micro-optodes to soluble nanoparticles. Moreover, the applicability of using heterologously expressed oxygen binding proteins and fluorescent proteins to determine changes in the cellular oxygen concentration are discussed as potential non-invasive cellular oxygen reporters.},
  language  = {en}
}