Research Report 2010 - MDC

Structure of the GroupGroup LeaderDr. Bettina ErdmannBettina ErdmannTechnical AssistantsMarianne VannauerMargit Vogel (part-time)Electron MicroscopyMethods of ultrastructural research are increasingly being used again to characterizegenetically modified specimens. During the last years, the electron microscopy (EM)facility has established and extended a panel of approaches, protocols and the technical basisfor morphological studies for a wide range of research projects. Based on two transmissionelectron microscopes (Zeiss 910, FEI Morgagni), both equipped with high resolution CCDcameras,we offer conventional plastic embedding for phenotyping, immunogold labeling withcryo methods as well as negative staining. In this way, collaborations with more than 25research groups in the house were performed, using the major model systems like cultured cells,mouse, yeast, zebrafish and biopsie probes from clinical projects. Only some typical examplesfor EM service are mentioned here:Phenotyping/ultrastructural characterizationBy using Lumox dishes for cell growth, we were able toretain the spatial arrangement of cultured cells duringEM processing. With this approach one can easily identifydifferentiation of stem cells even at the light miscroscopicallevel (Fig. a, collaboration with K. Eckert). Athigher magnifications we could detect cellular componentslike myofibrils and desmosomes in multilayeredcell cultures of cardiomyocytes (Fig. b, collaborationswith B. Gerull and C. Özcelik). Furthermore, we found awidened endoplasmic reticulum and signs of stress inglioma cell cultures (collaboration with H.Kettenmann). Fibroblast cell lines with different oncogenesrevealed remarkable changes in the number ofautophagosomes (collaboration with C. Schmitt).A range of research projects to `Function and Dysfunctionof the Nervous System` analyze model organismswith defects in nerve fibers and myelin structure.Together with C. Birchmeier, G. Lewin and A. Garratt auseful approach was developed to determine the numberof axons in peripheral nerves and the degree ofmyelination (g-ratio). A lot of phenotypes of mice andmole rats were described in this way (Fig. d), and thereforewe recently try to establish a new software modulefor the automatical detection of myelin figures.Other types of phenotyping at the ultrastructural levelreveal details that cannot be resolved by fluorescencelabeling and confocal microscopy. We identified andcounted the number of satellite cells in the developingmuscle in different mutant mice (Fig. e, collaborationwith C. Birchmeier). In contrast to fibroblasts orendothelial cells in this tissue, these satellite cells arelocated under the basal membrane close to the musclecells.Immunocytochemical labelingThe available expertise in the use of cryosectioningtechniques according to Tokuyasu was extended andincreasingly applied for immunolabeling of tissues.Although it often remains difficult to find an acceptablecompromise between fixation, structure preservationand the retaining of antigenicity, in some casesthese methods yield excellent results even in complextissue like brain. So we could detect a reduced numberof amyloid precursor protein (APP) molecules in Golgifields in the hippocampus of Sorla-deficient mice (Fig. c,collaboration with T. Willnow). Using Lamp1 as marker,we quantified with the same method lysosomalchanges in kidneys of chloride channel knock out mice(collaboration with T. Jentsch). In peroxisomes of the228 Technology Platforms