Dehnrheologie verdünnter, halbkonzentrierter und konzentrierter Polymerlösungen untersucht mit Capillary Breakup Extensional Rheometry (CaBER)

Ziel dieser Arbeit war es, die dehnrheologischen Eigenschaften von technisch relevanten, niederviskosen Polymerlösungen zu bestimmen. Die Messungen wurden am CaBER ? Gerät durchgeführt, das zu diesem Zweck um einen optischen Aufbau erweitert sowie um die Möglichkeit der Kraftmessung bei horizontaler Verstreckung ergänzt wurde. So war es möglich, an den untersuchten Systemen die absolute Dehnviskosität zu bestimmen und aus Referenzschermessungen das Trouton ? Verhältnis zu ermitteln

Characterization of a fold in TANGO1 evolved from SH3 domains for the export of bulky cargos

Bulky cargos like procollagens, apolipoproteins, and mucins exceed the size of conventional COPII vesicles. During evolution a process emerged in metazoans, predominantly governed by the TANGO1 protein family, that organizes cargo at the exit sites of the endoplasmic reticulum and facilitates export by the formation of tunnel-like connections between the ER and Golgi. Hitherto, cargo-recognition appeared to be mediated by an SH3-like domain. Based on structural and dynamic data as well as interaction studies from NMR spectroscopy and microscale thermophoresis presented here, we show that the luminal cargo-recognition domain of TANGO1 adopts a new functional fold for which we suggest the term MOTH (MIA, Otoraplin, TALI/TANGO1 homology) domain. These MOTH domains, as well as an evolutionary intermediate found in invertebrates, constitute a distinct domain family that emerged from SH3 domains and acquired the ability to bind collagen

CD31 and VEGF are prognostic biomarkers in early-stage, but not in late-stage, laryngeal squamous cell carcinoma

Abstract Background Patients suffering from squamous cell carcinoma of the larynx (LSCC) with lymphatic metastasis have a relatively poor prognosis and often require radical therapeutic management. The mechanisms which drive metastasis to the lymph nodes are largely unknown but may be promoted by a pro-angiogenic tumor microenvironment. In this study, we examined whether the number of microvessels and the expression level of vascular endothelial growth factor (VEGF) in the primary tumor are correlated with the degree of lymph node metastasis (N-stage), tumor staging (T) and survival time in LSCC patients. Methods Tissue-Microarrays of 97 LSCC patients were analyzed using immunohistochemistry. The expression of VEGF was scored as intensity of staining (low vs high) and the number of CD31-positive vessels (median </≥7 vessels per visual field) was counted manually. Scores were correlated with N-stage, T-stage and 5-year overall survival rate. Results A high expression of angiogenic biomarkers was not associated with poor overall survival in the overall cohort of patients. Instead high CD31 count was associated with early stage cancer (p = 0.004) and in this subgroup high VEGF expression correlated with poor survival (p = 0.032). Additionally, in early stage cancer a high vessel count was associated with an increased recurrence rate (p = 0.004). Conclusion Only in the early stage subgroup a high expression of angiogenic biomarkers was associated with reduced survival and an increased rate of recurrence. Thus, biomarkers of angiogenesis may be useful to identify high risk patients specifically in early stage LSCC

Structural insights into photosystem II assembly

International audienceBiogenesis of photosystem II (PSII), nature's water splitting catalyst, is assisted by auxiliary proteins that form transient complexes with PSII components to facilitate stepwise assembly events. Using cryo-electron microscopy, we solved the structure of such a PSII assembly intermediate from Thermosynechococcus elongatus at 2.94 Å resolution. It contains three assembly factors (Psb27, Psb28, Psb34) and provides detailed insights into their molecular function. Binding of Psb28 induces large conformational changes at the PSII acceptor side, which distort the binding pocket of the mobile quinone (QB) and replace the bicarbonate ligand of non-heme iron with glutamate, a structural motif found in reaction centers of non-oxygenic photosynthetic bacteria. These results reveal novel mechanisms that protect PSII from damage during biogenesis until water splitting is activated. Our structure further demonstrates how the PSII active site is prepared for the incorporation of the Mn4CaO5 cluster, which performs the unique water splitting reaction