New publication in Nature Methods

New publication in Nature Methods

News, Publications
Our paper entitled “Video rate volumetric Ca2+ imaging across cortical layers using Seeded Iterative Demixing (SID) microscopy” has been published in Nature Methods. We present a novel computational technique termed Seeded Iterative Demixing (SID) that allows for capturing neuronal dynamics in vivo within a volume of 900 × 900 × 260 µm, located as deep as 380 µm in the mouse cortex and hippocampus, and at a very high volume rate of 30 Hz. SID is based on Light Field Microscopy (LFM), a 3D imaging technique that our group has established in a previous publication as a versatile neural recording technique for weakly scattering specimen, such as larval zebrafish. SID extends LFM into more strongly scattering tissue such as the mammalian cortex by seeding a machine learning algorithm with remaining…
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New publication in Nature Methods

New publication in Nature Methods

News, Publications
Our paper entitled “Fast volumetric calcium imaging across multiple cortical layers using sculpted light” has been published in Nature Methods. In this work, we present a novel method based on light sculpting that enables unbiased single and dual-plane high-speed (up to 160 Hz) calcium imaging, as well as in vivo volumetric calcium imaging of a mouse cortical column (500x500x500 µm) at single-cell resolution and fast volume rates (3 - 6 Hz). This is achieved by tailoring the point-spread function of our microscope to the structures of interest while maximizing the signal-to-noise ratio while using a home-built fiber laser amplifier with pulses that are synchronized to the imaging voxel speed. Together, these innovations have enabled the near-simultaneous in-vivo recording of calcium dynamics of several thousand active neurons across cortical layers and…
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New publication in Cell

New publication in Cell

News, Publications
Our paper entitled "A force-induced directional switch of a molecular motor enables parallel microtubule bundle formation" by Maxim I. Molodtsov et al. has been published in Cell. Microtubule-organizing centers (MTOCs) nucleate microtubules that can grow autonomously in any direction. To generate bundles of parallel microtubules originating from a single MTOC, the growth of multiple microtubules needs to coordinated, but the underlying mechanism is unknown. Here, we show that a conserved two-component system consisting of the plus-endtracker EB1 and the minus-end-directed molecular motor Kinesin-14 is sufficient to promote parallel microtubule growth. The underlying mechanism relies on the ability of Kinesin-14 to guide growing plus ends along existing microtubules. The generality of this finding is supported by yeast, Drosophila, and human EB1/Kinesin-14 pairs. We demonstrate that plus-end guiding involves a directional switch…
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New publication in Nature Communications

New publication in Nature Communications

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Our paper entitled “Direct Detection of a Single Photon by Humans” by Tinsley J. N. et. al., has been published in Nature Communications. In this study we have shown that humans are capable of detecting a single photon onto their eyes with a probability above chance. This was done by developing a quantum light source based on spontaneous parametric down-conversion (SPDC) which can generate single-photon states of light and combining it with a state-of-the-art psychophysics procedure. Thereby we could show that the human visual system including the post-processing performed by the retina and the brain can detect a single photon incident onto the eye. Read the publication or a short summary. Please have also a look at the Nature News article by Davide Castelvecchi as well as the articles on…
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New publication in J. Phys. Chem. B

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Together with our colleagues at the Institute for Biophysical Dynamics at the University of Chicago, we have developed a method using infrared spectroscopy and atomistic modeling that would allow to better understand the mechanism behind the extreme ion selectivity and transport properties in ion channels. Our findings have recently been published in The Journal of Physical Chemistry B. [caption id="attachment_1312" align="aligncenter" width="584"] Location of the potassium channel KcsA in the cell membrane of bacteria. The schematic illustration on the right shows the changes in strength and direction of vibrational coupling inside the filter depending on the ion species, as found by the study. @David S. Goodsell & RCSB Protein Data Bank[/caption] Ion channels are essential structures of life. Ion channels are specialized pores in the cell membrane and move charged…
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New Publication in Analytical Chemistry

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Together with our collaborator Markus Arndt we published in Analytical Chemistry on how to improve Laser-induced acoustic desorption (LIAD) for natural biochromophores. This methodology might enable us to use fragile biomolecules in Quantum-enhanced metrology experiments. Link to Paper or look up other publications of our group. Ugur Sezer, Lisa Wörner, Johannes Horak, Lukas Felix, Jens Tüxen, Christoph Götz, Alipasha Vaziri, Marcel Mayor, and Markus Arndt Laser-induced acoustic desorption of natural and functionalized biochromophores Anal. Chem., 2015, 87 (11), pp 5614–5619 (Download)
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New Paper in eLife on a Non-Conventional Translocation Mechanism for Motor Proteins

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Motors proteins of the conserved kinesin-14 family have important roles in mitotic spindle organization and chromosome segregation. Previous studies have indicated that kinesin-14 motors are non-processive enzymes, working in the context of multi-motor ensembles that collectively organize microtubule networks. Here we show that the yeast kinesin-14 Kar3 generates processive movement as a heterodimer with the non-motor proteins Cik1 or Vik1. By analyzing the single-molecule properties of engineered motors we demonstrate that the non-catalytic domain has a key role in the motility mechanism by acting as a 'foothold' that allows Kar3 to bias translocation towards the minus end. This mechanism rivals the speed and run length of conventional motors, can support transport of the Ndc80 complex in vitro and is critical for Kar3 function in vivo. Our findings provide an example for…
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New Paper in Biomedical Optics Express

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Our recent paper "Optimizing and extending light-sculpting microscopy for fast functional imaging in neuroscience" on the improvement of our previously published imaging technique can be accessed via this Website. [caption id="attachment_1218" align="alignright" width="1020"] Experimental setup and various modalities of light sculpting microscopy.[/caption]  
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