@article{SchneiderKleinMielichSuessetal.2015,
  author    = {Schneider, Johannes and Klein, Teresa and Mielich-S{\"u}ss, Benjamin and Koch, Gudrun and Franke, Christian and Kuipers, Oskar P. and Kov{\´a}cs, {\´A}kos T. and Sauer, Markus and Lopez, Daniel},
  title     = {Spatio-temporal Remodeling of Functional Membrane Microdomains Organizes the Signaling Networks of a Bacterium},
  series = {PLoS Genetics},
  volume    = {11},
  journal   = {PLoS Genetics},
  number    = {4},
  doi       = {10.1371/journal.pgen.1005140},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-125577},
  pages     = {e1005140},
  year      = {2015},
  abstract  = {Lipid rafts are membrane microdomains specialized in the regulation of numerous cellular processes related to membrane organization, as diverse as signal transduction, protein sorting, membrane trafficking or pathogen invasion. It has been proposed that this functional diversity would require a heterogeneous population of raft domains with varying compositions. However, a mechanism for such diversification is not known. We recently discovered that bacterial membranes organize their signal transduction pathways in functional membrane microdomains (FMMs) that are structurally and functionally similar to the eukaryotic lipid rafts. In this report, we took advantage of the tractability of the prokaryotic model Bacillus subtilis to provide evidence for the coexistence of two distinct families of FMMs in bacterial membranes, displaying a distinctive distribution of proteins specialized in different biological processes. One family of microdomains harbors the scaffolding flotillin protein FloA that selectively tethers proteins specialized in regulating cell envelope turnover and primary metabolism. A second population of microdomains containing the two scaffolding flotillins, FloA and FloT, arises exclusively at later stages of cell growth and specializes in adaptation of cells to stationary phase. Importantly, the diversification of membrane microdomains does not occur arbitrarily. We discovered that bacterial cells control the spatio-temporal remodeling of microdomains by restricting the activation of FloT expression to stationary phase. This regulation ensures a sequential assembly of functionally specialized membrane microdomains to strategically organize signaling networks at the right time during the lifespan of a bacterium.},
  language  = {en}
}
@phdthesis{Franke2023,
  author    = {Franke, Christian},
  title     = {Gelenkknorpelintegration im Tissue Engineering: Untersuchung von Polyethylenglykol- und Hyalurons{\"a}ure-Komponenten f{\"u}r ein Adh{\"a}sivum und Etablierung eines biomechanischen Versuchsmodells},
  doi       = {10.25972/OPUS-32337},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-323375},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2023},
  abstract  = {Gelenkknorpel besitzt aufgrund seiner avaskul{\"a}ren Natur und der fehlenden mitotischen Aktivit{\"a}t der Chondrozyten bei Sch{\"a}den kaum Potential zur Selbstheilung. Traumatische L{\"a}sionen und degenerative Ver{\"a}nderungen m{\"u}nden im Krankheitsbild der Osteoarthrose, welches mit dem Untergang des Gelenkknorpels einhergeht. Ein neuerer Therapieansatz ist das Tissue Engineering von Gelenkknorpel, wobei jedoch die laterale Integration der Implantate mit dem nativen Knorpelgewebe problematisch bleibt. Ein Adh{\"a}sivum kann neben einer ad{\"a}quaten Sofortadh{\"a}sion die Langzeitintegration f{\"o}rdern. In dieser Arbeit wurden verschiedene Polyethylenglykol (PEG)-basierte Zweikomponentenkleber, ausgehend vom kommerziell erh{\"a}ltlichen Gewebekleber CoSeal™, auf ihre Eignung f{\"u}r Gelenkknorpel untersucht. Dabei wurde Hyalurons{\"a}ure (HA) als physiologischer Bestandteil von Gelenkknorpel in thiolierter Form (HA-SH) als Komponente verwendet und auf seine prointegrativen Eigenschaften untersucht. Der den CoSeal™-Komponenten entsprechende 4-Succinimidyl-Glutarat/4-Thiol-PEG (4SG/4T-PEG)-Kleber hatte sich trotz seiner hohen Sofortadh{\"a}sionskraft auch nach der Substitution des 4T-PEG mit HA-SH als zu schnell in fl{\"u}ssiger Umgebung degradierend gezeigt, um eine suffiziente Langzeitintegration zu erreichen. Durch die Verwendung der langsamer degradierenden funktionellen 4-Succinimidyl-Carbonat-PEG (4C-PEG)-Komponente konnte die Langzeitadh{\"a}sionskraft in Kombination mit 4-Amin-PEG (4A-PEG) durch die stabilere Amid-Bindung zum einen und in Kombination mit HA-SH zum anderen signifikant gesteigert werden. Immunhistochemisch konnten bei beiden HA-haltigen Klebern Zeichen von Knorpelintegration nachgewiesen werden, w{\"a}hrend der 4C/4A-PEG-Kleber keine Integrationszeichen aufwies. Im 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium Bromid (MTT)-Assay war bei keinem Adh{\"a}sivum eine zytotoxische Wirkung zu erkennen. Insgesamt bieten die untersuchten PEG-basierten Adh{\"a}siva im Vergleich zu den weitverbreiteten Fibrinklebern eine deutlich h{\"o}here Sofortadh{\"a}sion, welche vergleichbar mit glutaraldehydbasierten Klebern ist. Allerdings k{\"o}nnen die initialen adh{\"a}siven Kr{\"a}fte, trotz histologisch nachweisbaren Integrationszeichen bei Inkorporation von HA, nicht langfristig aufrechterhalten werden, so dass Fibrinkleber weiterhin die Spitzengruppe in Sachen Langzeitadh{\"a}sion bilden. Da PEG eine ausgezeichnete Biokompatibilit{\"a}t, einfache Anwendbarkeit und zahlreiche weitere chemische Anpassungsm{\"o}glichkeiten zur Feinabstimmung der Degradationseigenschaften bietet, ist in Zukunft ein erfolgreicher Einsatz auch im Bereich von Gelenkknorpel denkbar. F{\"u}r die experimentelle Untersuchung von Adh{\"a}siva und Gelenkknorpel werden biomechanische Versuchsmodelle ben{\"o}tigt. Der Tensile-Test des Sandwich-Modells konnte im Rahmen dieser Arbeit erfolgreich etabliert und ein Protokoll festgelegt werden. In einem vergleichenden Versuch mit dem Push-Out-Test des Disc-Ring-Modells, welches als Referenzmodell dient, konnte in Bezug auf die Reproduzierbarkeit und Qualit{\"a}t der Messergebnisse die Gleichwertigkeit gezeigt werden. Insgesamt bietet er eine gute Alternative zum Push-Out-Test, um weiterf{\"u}hrende Fragestellung, wie z.B. extrinsische Kraftwirkungen auf das Konstrukt, zu untersuchen.},
  subject      = {Knorpel},
  language  = {de}
}
@phdthesis{Franke2019,
  author    = {Franke, Christian},
  title     = {Advancing Single-Molecule Localization Microscopy: Quantitative Analyses and Photometric Three-Dimensional Imaging},
  doi       = {10.25972/OPUS-15635},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-156355},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {Since its first experimental implementation in 2005, single-molecule localization microscopy (SMLM) emerged as a versatile and powerful imaging tool for biological structures with nanometer resolution. By now, SMLM has compiled an extensive track-record of novel insights in sub- and inter- cellular organization.\\ Moreover, since all SMLM techniques rely on the analysis of emission patterns from isolated fluorophores, they inherently allocate molecular information \$per\$ \$definitionem\$.\\ Consequently, SMLM transitioned from its origin as pure high-resolution imaging instrument towards quantitative microscopy, where the key information medium is no longer the highly resolved image itself, but the raw localization data set.\\ The work presented in this thesis is part of the ongoing effort to translate those \$per\$ \$se\$ molecular information gained by SMLM imaging to insights into the structural organization of the targeted protein or even beyond. Although largely consistent in their objectives, the general distinction between global or segmentation clustering approaches on one side and particle averaging or meta-analyses techniques on the other is usually made.\\ During the course of my thesis, I designed, implemented and employed numerous quantitative approaches with varying degrees of complexity and fields of application.\\ \\ In my first major project, I analyzed the localization distribution of the integral protein gp210 of the nuclear pore complex (NPC) with an iterative \textit{k}-means algorithm. Relating the distinct localization statistics of separated gp210 domains to isolated fluorescent signals led, among others, to the conclusion that the anchoring ring of the NPC consists of 8 homo-dimers of gp210.\\ This is of particular significance, both because it answered a decades long standing question about the nature of the gp210 ring and it showcased the possibility to gain structural information well beyond the resolution capabilities of SMLM by crafty quantification approaches.\\ \\ The second major project reported comprises an extensive study of the synaptonemal complex (SNC) and linked cohesin complexes. Here, I employed a multi-level meta-analysis of the localization sets of various SNC proteins to facilitate the compilation of a novel model of the molecular organization of the major SNC components with so far unmatched extend and detail with isotropic three-dimensional resolution.\\ In a second venture, the two murine cohesin components SMC3 and STAG3 connected to the SNC were analyzed. Applying an adapted algorithm, considering the disperse nature of cohesins, led to the realization that there is an apparent polarization of those cohesin complexes in the SNC, as well as a possible sub-structure of STAG3 beyond the resolution capabilities of SMLM.\\ \\ Other minor projects connected to localization quantification included the study of plasma membrane glycans regarding their overall localization distribution and particular homogeneity as well as the investigation of two flotillin proteins in the membrane of bacteria, forming clusters of distinct shapes and sizes.\\ \\ Finally, a novel approach to three-dimensional SMLM is presented, employing the precise quantification of single molecule emitter intensities. This method, named TRABI, relies on the principles of aperture photometry which were improved for SMLM.\\ With TRABI it was shown, that widely used Gaussian fitting based localization software underestimates photon counts significantly. This mismatch was utilized as a \$z\$-dependent parameter, enabling the conversion of 2D SMLM data to a virtual 3D space. Furthermore it was demonstrated, that TRABI can be combined beneficially with a multi-plane detection scheme, resulting in superior performance regarding axial localization precision and resolution.\\ Additionally, TRABI has been subsequently employed to photometrically characterize a novel dye for SMLM, revealing superior photo-physical properties at the single-molecule level.\\ Following the conclusion of this thesis, the TRABI method and its applications remains subject of diverse ongoing research.},
  subject      = {Einzelmolek{\"u}lmikroskopie},
  language  = {en}
}