@article {65264, title = {Tissue clearing and its applications in~neuroscience.}, journal = {Nature Reviews Neuroscience}, volume = {21}, year = {2020}, month = {2020 Jan 02}, pages = {61-79}, abstract = {

State-of-the-art tissue-clearing methods provide subcellular-level optical access to intact tissues from individual organs and even to some entire mammals. When combined with light-sheet microscopy and automated approaches to image analysis, existing tissue-clearing methods can speed up and may reduce the cost of conventional histology by several orders of magnitude. In addition, tissue-clearing chemistry allows whole-organ antibody labelling, which can be applied even to thick human tissues. By combining the most powerful labelling, clearing, imaging and data-analysis tools, scientists are extracting structural and functional cellular and subcellular information on complex mammalian bodies and large human specimens at an accelerated pace. The rapid generation of terabyte-scale imaging data furthermore creates a high demand for efficient computational approaches that tackle challenges in large-scale data analysis and management. In this Review, we discuss how tissue-clearing methods could provide an unbiased, system-level view of mammalian bodies and human specimens and discuss future opportunities for the use of these methods in human neuroscience.

}, issn = {1471-0048}, doi = {10.1038/s41583-019-0250-1}, author = {Ueda, Hiroki R and Ert{\"u}rk, Ali and Chung, Kwanghun and Gradinaru, Viviana and Ch{\'e}dotal, Alain and Tomancak, Pavel and Keller, Philipp J} } @article {5935, title = {Towards comprehensive cell lineage reconstructions in complex organisms using light-sheet microscopy.}, journal = {Development, Growth and Differentiation}, volume = {55}, year = {2013}, month = {2013 Apr 29}, pages = {563-78}, abstract = {

Understanding the development of complex multicellular organisms as a function of the underlying cell behavior is one of the most fundamental goals of developmental biology. The ability to quantitatively follow cell dynamics in entire developing embryos is an indispensable step towards such a system-level understanding. In recent years, light-sheet fluorescence microscopy has emerged as a particularly promising strategy for recording the in vivo data required to realize this goal. Using light-sheet fluorescence microscopy, entire complex organisms can be rapidly imaged in three dimensions at sub-cellular resolution, achieving high temporal sampling and excellent signal-to-noise ratio without damaging the living specimen or bleaching fluorescent markers. The resulting datasets allow following individual cells in vertebrate and higher invertebrate embryos over up to several days of development. However, the complexity and size of these multi-terabyte recordings typically preclude comprehensive manual analyses. Thus, new computational approaches are required to automatically segment cell morphologies, accurately track cell identities and systematically analyze cell behavior throughout embryonic development. We review current efforts in light-sheet microscopy and bioimage informatics towards this goal, and argue that comprehensive cell lineage reconstructions are finally within reach for many key model organisms, including fruit fly, zebrafish and mouse.

}, issn = {1440-169X}, doi = {10.1111/dgd.12063}, author = {Amat, Fernando and Keller, Philipp J} } @article {43051, title = {Tandem fluorescent protein timers for in vivo analysis of protein dynamics.}, journal = {Nature Biotechnology}, volume = {30}, year = {2012}, month = {2012 Jun 24}, pages = {708-14}, abstract = {

The functional state of a cell is largely determined by the spatiotemporal organization of its proteome. Technologies exist for measuring particular aspects of protein turnover and localization, but comprehensive analysis of protein dynamics across different scales is possible only by combining several methods. Here we describe tandem fluorescent protein timers (tFTs), fusions of two single-color fluorescent proteins that mature with different kinetics, which we use to analyze protein turnover and mobility in living cells. We fuse tFTs to proteins in yeast to study the longevity, segregation and inheritance of cellular components and the mobility of proteins between subcellular compartments; to measure protein degradation kinetics without the need for time-course measurements; and to conduct high-throughput screens for regulators of protein turnover. Our experiments reveal the stable nature and asymmetric inheritance of nuclear pore complexes and identify regulators of N-end rule{\textendash}mediated protein degradation.

}, keywords = {Green Fluorescent Proteins, High-Throughput Screening Assays, Kinetics, Nuclear Pore, Protein Stability, Proteins, Proteolysis, Saccharomyces cerevisiae, Subcellular Fractions}, issn = {1546-1696}, doi = {10.1038/nbt.2281}, author = {Khmelinskii, Anton and Keller, Philipp J and Bartosik, Anna and Meurer, Matthias and Barry, Joseph D and Mardin, Balca R and Kaufmann, Andreas and Trautmann, Susanne and Wachsmuth, Malte and Pereira, Gislene and Huber, Wolfgang and Schiebel, Elmar and Knop, Michael} } @article {1688, title = {Three-dimensional microtubule behavior in Xenopus egg extracts reveals four dynamic states and state-dependent elastic properties.}, journal = {Biophysical Journal}, volume = {95}, year = {2008}, month = {2008 Aug}, pages = {1474-86}, abstract = {

Although microtubules are key players in many cellular processes, very little is known about their dynamic and mechanical properties in physiological three-dimensional environments. The conventional model of microtubule dynamic instability postulates two dynamic microtubule states, growth and shrinkage. However, several studies have indicated that such a model does not provide a comprehensive quantitative and qualitative description of microtubule behavior. Using three-dimensional laser light-sheet fluorescence microscopy and a three-dimensional sample preparation in spacious Teflon cylinders, we measured microtubule dynamic instability and elasticity in interphase Xenopus laevis egg extracts. Our data are inconsistent with a two-state model of microtubule dynamic instability and favor an extended four-state model with two independent metastable pause states over a three-state model with a single pause state. Moreover, our data on kinetic state transitions rule out a simple GTP cap model as the driving force of microtubule stabilization in egg extracts on timescales of a few seconds or longer. We determined the three-dimensional elastic properties of microtubules as a function of both the contour length and the dynamic state. Our results indicate that pausing microtubules are less flexible than growing microtubules and suggest a growth-speed-dependent persistence length. These data might hint toward mechanisms that enable microtubules to efficiently perform multiple different tasks in the cell and suggest the development of a unified model of microtubule dynamics and microtubule mechanics.

}, keywords = {Animals, Elasticity, Imaging, Mechanical, Microtubules, Ovum, Stress, Three-Dimensional, Xenopus laevis}, issn = {1542-0086}, doi = {10.1529/biophysj.107.128223}, author = {Keller, Philipp J and Pampaloni, Francesco and Lattanzi, Gianluca and Stelzer, Ernst H K} } @article {1689, title = {Three-dimensional preparation and imaging reveal intrinsic microtubule properties.}, journal = {Nature Methods}, volume = {4}, year = {2007}, month = {2007 Oct}, pages = {843-6}, abstract = {

We present an experimental investigation of microtubule dynamic instability in three dimensions, based on laser light-sheet fluorescence microscopy. We introduce three-dimensional (3D) preparation of Xenopus laevis egg extracts in Teflon-based cylinders and provide algorithms for 3D image processing. Our approach gives experimental access to the intrinsic dynamic properties of microtubules and to microtubule population statistics in single asters. We obtain evidence for a stochastic nature of microtubule pausing.

}, keywords = {Animals, Computer-Assisted, Fluorescence, Image Processing, Imaging, Microscopy, Microtubules, Ovum, Three-Dimensional, Xenopus laevis}, issn = {1548-7091}, doi = {10.1038/nmeth1087}, author = {Keller, Philipp J and Pampaloni, Francesco and Stelzer, Ernst H K} }