From imaging service to quantitative analysis of ultrastructural details

The microscopy and cryo-electron microscopy service group provides a broad range of imaging techniques combining both, light microscopy (LM) and transmission electron microscopy (TEM). Our group supports scientists and students from all departments and independent OWL research groups in planning and performing their imaging tasks at all levels ranging from basic user training to the implementation of advanced imaging workflows. We also emphasize on implementing data analysis tools, processing pipelines and workflow automation which are crucial to extract and quantify meaningful biological information from complex 2D, 3D and 4D imaging data.

Our group hosts various light microscope systems operated as shared equipment which are open to all users within the institute. This includes widefield fluorescence microscopes, confocal laser scanning microscopes (in part equipped with Airyscan super-resolution detectors and an NDD detector for 2-photon imaging), highly automated screening microscopes, a confocal STED super-resolution microscope as well as a dedicated 3D light sheet microscope. Most of our light microscopes are equipped for live cell imaging.

(from left to right) Confocal image of a mouse blastocyste; montage of TEM images taken from a mouse blastocyste after resin embedding and ultrathin-sectioning; zoom into the highlighted region; quantitativ and statistical analysis of ultrastructural details such as nuclei (cyan). mitochondria (red) and lipd droplets (green). Project with the group of Aydan Bulut-Karslıoğlu.

(from left to right) Confocal image of a mouse blastocyste; montage of TEM images taken from a mouse blastocyste after resin embedding and ultrathin-sectioning; zoom into the highlighted region; quantitativ and statistical analysis of ultrastructural details such as nuclei (cyan). mitochondria (red) and lipd droplets (green). Project with the group of Aydan Bulut-Karslıoğlu.

Due to the technical complexity of TEM sample preparation and imaging, TEM is provided as full service and is performed in close collaboration with individual scientists and research groups, respectively. We currently host three transmission electron microscopes including a 300 kV Tecnai G2 Polara cryo-TEM equipped with Gatan k2 summit direct electron detector. Our group supports conventional TEM methods such as ultra-thin sectioning of plastic-embedded samples, immunogold-labelling or metal-shadowing of nucleic acids and nucleic acid-protein complexes. Another focus lies on structure determination of protein complexes using single particle cryo-EM which we perform in close collaboration with our main partners Christian Spahn (IMPB, Charité Berlin) and Petra Wendler (University Potsdam)

Our research focus lies on the implementation and improvement of new imaging and image analysis techniques that could be of strategical interest for our users. One example are correlative microscopy techniques that bridge the potential of both, light and electron microscopy. Hereby, light microscopy is commonly applied to monitor the formation of biological structures e.g. using 3D cell culture systems and to identify specific incidents at a given time point which are than imaged at higher resolution using TEM and SEM upon plastic-embedding and sample vitrification, respectively. Other examples are the implementation of super-resolutions cryo-expansion techniques, and the development of imaging methods and assay that are based on fluorescence life-time measurements (FLIM).