Service

1. Sample preparation for electron microscopy

• Sample preparation for cryo-immobilization (High-pressure freezing, Plunge freezing), or chemical fixation, including microwave processing
• Sectioning: ultrathin, semi-thin, serial sections, cryo-sections (Tokuyasu)
• Positive contrasting (pre- or post-embedding) and negative staining
• Immuno-labelling/staining (as pre-embedding or labeling on plastic- and cryo-sections)

The EM facility has established protocols that maximize the preservation of morphology at the EM level for each of the major model system used at MPI-CBG (cultured cells, C. elegans, Drosophila, mouse, zebrafish ...). Routine immuno-localization techniques for popular antigens such as GFP are also established. However, the best sample fixation and preparation techniques may differ for different antigens and antibodies and thus continuous development is required. We also have protocols for various Light/Electron microscopy correlative approaches.

2. Imaging

• Data acquisition in transmission electron microscopy (TEM), cryoTEM or SEM
• Electron tomography (3D imaging)
• Correlative light electron microscopy/tomography (CLEM)
• Serial block-face scanning electron microscopy (SBF-SEM)

In addition to image acquisition, the EM facility provides data storage and image-processing support (registration, 3D reconstruction, image segmentation).

Facility

• Provision of EM-specified chemicals and supplies for users
• Support and training in the methods listed in “Service” above and more (e.g. grid preparation…)
• Access to the state-of-the-art equipment of the facility
• Training and support in (cryo)ultramicrotome and electron microscope usage
• Support and assistance in cell morphology, ultrastructure and data interpretation
• Basic training courses for PhD-students (Dresden International PhD Program)
• Basic and advanced training in electron tomography (annual international workshop)

Technology development

The EM facility is actively involved in the development of new technologies in EM: In 3-dimensional electron microscopy (3DEM), like can be obtained by electron tomography, the segmentation of structures of interest in the 3D space is a major challenge. We have developed publicly available software and reference EM datasets, for the automatic tracing of microtubules in electron tomography (Weber et al., 2012). This software can be evaluated on our microtubule segmentation portal: http://amitube.mpi-cbg.de. We have also been developing new approaches for registration of serial tomography sections. Likewise, the EM facility has been developing multiple correlative light/electron microscopy (CLEM) approaches (Gibson et al., 2014)