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). We support scientists and students from all departments and independent OWL research groups in planning, performing, analyzing, interpreting, and visualizing their imaging tasks up to publication. Our group thereby supports all levels of your imaging project ranging from basic user training, sample preparation techniques 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 including 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 FLIM-STED super-resolution microscope as well as a dedicated 3D light sheet microscope. Most of our light microscopes are equipped for live cell imaging. Our light microscopes are operated as shared equipment and are used by a highly active but also diverse community of users from all research groups across the institute.

(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 and metal-shadowing techniques. In cryo -EM, we focus on structure determination of protein complexes using single particle techniques, providing access to the infrastructure for sample screening, data collection and image processing.

Our research focus as service group lies on the implementation and improvement of new imaging and image analysis methods 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 identify biological events in living cells or 3D model systems, that are then imaged at higher resolution using TEM and SEM techniques. Other examples are the implementation of super-resolutions cryo-expansion techniques, and the development of imaging assays that are based on fluorescence life-time measurements (FLIM; Hochmair et al., 2022, EMBO J). In addition, we are working on developing routines for smart microscopy approaches, that can autonomously identify targets, trace objects of interests, and at some point in the future, maybe even manipulate them.