University of Tuebingen 2 articles published in JoVE Environment Laboratory Simulation of an Iron(II)-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria Markus Maisch1,2, Wenfang Wu1, Andreas Kappler1, Elizabeth D. Swanner1,2 1Department of Geosciences, University of Tuebingen, 2Department of Geological and Atmospheric Sciences, Iowa State University We simulated a Precambrian ferruginous marine upwelling system in a lab-scale vertical flow-through column. The goal was to understand how geochemical profiles of O2 and Fe(II) evolve as cyanobacteria produce O2. The results show the establishment of a chemocline due to Fe(II) oxidation by photosynthetically produced O2. Neuroscience Ex Vivo Optogenetic Dissection of Fear Circuits in Brain Slices Daniel Bosch1, Douglas Asede2, Ingrid Ehrlich1 1Hertie Institute for Clinical Brain Research and Werner Reichardt Centre for Integrative Neuroscience, University of Tuebingen, 2Max Planck Florida Institute for Neuroscience Optogenetic approaches are widely used to manipulate neural activity and assess the consequences for brain function. Here, a technique is outlined that upon in vivo expression of the optical activator Channelrhodopsin, allows for ex vivo analysis of synaptic properties of specific long range and local neural connections in fear-related circuits.