@phdthesis{323,
  abstract     = {In the here presented thesis, we explore the role of branched actin networks in cell migration and antigen presentation, the two most relevant processes in dendritic cell biology. Branched actin networks construct lamellipodial protrusions at the leading edge of migrating cells. These are typically seen as adhesive structures, which mediate force transduction to the extracellular matrix that leads to forward locomotion. We ablated Arp2/3 nucleation promoting factor WAVE in DCs and found that the resulting cells lack lamellipodial protrusions. Instead, depending on the maturation state, one or multiple filopodia were formed. By challenging these cells in a variety of migration assays we found that lamellipodial protrusions are dispensable for the locomotion of leukocytes and actually dampen the speed of migration. However, lamellipodia are critically required to negotiate complex environments that DCs experience while they travel to the next draining lymph node. Taken together our results suggest that leukocyte lamellipodia have rather a sensory- than a force transducing function. Furthermore, we show for the first time structure and dynamics of dendritic cell F-actin at the immunological synapse with naïve T cells. Dendritic cell F-actin appears as dynamic foci that are nucleated by the Arp2/3 complex. WAVE ablated dendritic cells show increased membrane tension, leading to an altered ultrastructure of the immunological synapse and severe T cell priming defects. These results point towards a previously unappreciated role of the cellular mechanics of dendritic cells in T cell activation. Additionally, we present a novel cell culture based system for the differentiation of dendritic cells from conditionally immortalized hematopoietic precursors. These precursor cells are genetically tractable via the CRISPR/Cas9 system while they retain their ability to differentiate into highly migratory dendritic cells and other immune cells. This will foster the study of all aspects of dendritic cell biology and beyond. },
  author       = {Leithner, Alexander F},
  issn         = {2663-337X},
  pages        = {99},
  publisher    = {Institute of Science and Technology Austria},
  title        = {{Branched actin networks in dendritic cell biology}},
  doi          = {10.15479/AT:ISTA:th_998},
  year         = {2018},
}

@article{326,
  abstract     = {Three-dimensional (3D) super-resolution microscopy technique structured illumination microscopy (SIM) imaging of dendritic spines along the dendrite has not been previously performed in fixed tissues, mainly due to deterioration of the stripe pattern of the excitation laser induced by light scattering and optical aberrations. To address this issue and solve these optical problems, we applied a novel clearing reagent, LUCID, to fixed brains. In SIM imaging, the penetration depth and the spatial resolution were improved in LUCID-treated slices, and 160-nm spatial resolution was obtained in a large portion of the imaging volume on a single apical dendrite. Furthermore, in a morphological analysis of spine heads of layer V pyramidal neurons (L5PNs) in the medial prefrontal cortex (mPFC) of chronic dexamethasone (Dex)-treated mice, SIM imaging revealed an altered distribution of spine forms that could not be detected by high-NA confocal imaging. Thus, super-resolution SIM imaging represents a promising high-throughput method for revealing spine morphologies in single dendrites.},
  author       = {Sawada, Kazuaki and Kawakami, Ryosuke and Shigemoto, Ryuichi and Nemoto, Tomomi},
  journal      = {European Journal of Neuroscience},
  number       = {9},
  pages        = {1033 -- 1042},
  publisher    = {Wiley},
  title        = {{Super resolution structural analysis of dendritic spines using three-dimensional structured illumination microscopy in cleared mouse brain slices}},
  doi          = {10.1111/ejn.13901},
  volume       = {47},
  year         = {2018},
}

@inbook{1094,
  abstract     = {Immunogold labeling of freeze-fracture replicas has recently been used for high-resolution visualization of protein localization in electron microscopy. This method has higher labeling efficiency than conventional immunogold methods for membrane molecules allowing precise quantitative measurements. However, one of the limitations of freeze-fracture replica immunolabeling is difficulty in keeping structural orientation and identifying labeled profiles in complex tissues like brain. The difficulty is partly due to fragmentation of freeze-fracture replica preparations during labeling procedures and limited morphological clues on the replica surface. To overcome these issues, we introduce here a grid-glued replica method combined with SEM observation. This method allows histological staining before dissolving the tissue and easy handling of replicas during immunogold labeling, and keeps the whole replica surface intact without fragmentation. The procedure described here is also useful for matched double-replica analysis allowing further identification of labeled profiles in corresponding P-face and E-face.},
  author       = {Harada, Harumi and Shigemoto, Ryuichi},
  booktitle    = {High-Resolution Imaging of Cellular Proteins},
  issn         = {1611-3349},
  pages        = {203 -- 216},
  publisher    = {Springer},
  title        = {{Immunogold protein localization on grid-glued freeze-fracture replicas}},
  doi          = {10.1007/978-1-4939-6352-2_12},
  volume       = {1474},
  year         = {2016},
}

@article{1993,
  abstract     = {The fitness effects of symbionts on their hosts can be context-dependent, with usually benign symbionts causing detrimental effects when their hosts are stressed, or typically parasitic symbionts providing protection towards their hosts (e.g. against pathogen infection). Here, we studied the novel association between the invasive garden ant Lasius neglectus and its fungal ectosymbiont Laboulbenia formicarum for potential costs and benefits. We tested ants with different Laboulbenia levels for their survival and immunity under resource limitation and exposure to the obligate killing entomopathogen Metarhizium brunneum. While survival of L. neglectus workers under starvation was significantly decreased with increasing Laboulbenia levels, host survival under Metarhizium exposure increased with higher levels of the ectosymbiont, suggesting a symbiont-mediated anti-pathogen protection, which seems to be driven mechanistically by both improved sanitary behaviours and an upregulated immune system. Ants with high Laboulbenia levels showed significantly longer self-grooming and elevated expression of immune genes relevant for wound repair and antifungal responses (β-1,3-glucan binding protein, Prophenoloxidase), compared with ants carrying low Laboulbenia levels. This suggests that the ectosymbiont Laboulbenia formicarum weakens its ant host by either direct resource exploitation or the costs of an upregulated behavioural and immunological response, which, however, provides a prophylactic protection upon later exposure to pathogens. },
  author       = {Konrad, Matthias and Grasse, Anna V and Tragust, Simon and Cremer, Sylvia},
  issn         = {1471-2954},
  journal      = {Proceedings of the Royal Society of London Series B Biological Sciences},
  number       = {1799},
  publisher    = {The Royal Society},
  title        = {{Anti-pathogen protection versus survival costs mediated by an ectosymbiont in an ant host}},
  doi          = {10.1098/rspb.2014.1976},
  volume       = {282},
  year         = {2015},
}