Charakterisierung von hERG-Kaliumkanalmutationen bei Patienten mit LQT2-Syndrom:Elektrophysiologische Untersuchungen im heterologen Expressionssystem

Mutationen im human ether-à-go-go related gene (hERG) können zum LQT2-Syndrom mit einer verlängerten QT-Zeit führen, das Arrhythmien bis hin zum Herzstillstand auslösen kann. Mittels voltage clamp wurden Stromamplituden sowie Aktivierungs- u. Inaktivierungsverhalten der Mutationen T623I, G628S, K638Q, Y611X, Q688X und R1055Q im heterologen Expressionssystem Xenopus laevis analysiert. Wildtyp (WT) und alle Coexpressionen zeigten hERG-typische Membranströme, die Mutationen nicht. Keine Coexpression führte zur vollständigen Hemmung des Gesamtstroms. T623I und Y611X zeigten ein rezessives Verhalten. G628S, K638Q, Q688X und R1055Q zeigten mit 70-98% bezogen auf den WT eine gewisse Wiederherstellung der Kanalfunktionalität. Diese Mutationen scheinen mit den WT-Untereinheiten heterotetramere funktionelle Kanäle ausbilden zu können. Es zeigten sich keine Veränderungen der Gleichgewichtsaktivierung; bei einigen Mutationen traten Linksverschiebungen in der Inaktivierung auf, was physiologisch zu einem verringerten Repolarisierungspotential führen würde. R1055Q zeigte keine Veränderung und kann als Polymorphismus eingeordnet werden

Correlated Multimodal Imaging in Life Sciences:Expanding the Biomedical Horizon

International audienceThe frontiers of bioimaging are currently being pushed toward the integration and correlation of several modalities to tackle biomedical research questions holistically and across multiple scales. Correlated Multimodal Imaging (CMI) gathers information about exactly the same specimen with two or more complementary modalities that-in combination-create a composite and complementary view of the sample (including insights into structure, function, dynamics and molecular composition). CMI allows to describe biomedical processes within their overall spatio-temporal context and gain a mechanistic understanding of cells, tissues, diseases or organisms by untangling their molecular mechanisms within their native environment. The two best-established CMI implementations for small animals and model organisms are hardware-fused platforms in preclinical imaging (Hybrid Imaging) and Correlated Light and Electron Microscopy (CLEM) in biological imaging. Although the merits of Preclinical Hybrid Imaging (PHI) and CLEM are well-established, both approaches would benefit from standardization of protocols, ontologies and data handling, and the development of optimized and advanced implementations. Specifically, CMI pipelines that aim at bridging preclinical and biological imaging beyond CLEM and PHI are rare but bear great potential to substantially advance both bioimaging and biomedical research. CMI faces three mai

Correlated Multimodal Imaging in Life Sciences:Expanding the Biomedical Horizon

International audienceThe frontiers of bioimaging are currently being pushed toward the integration and correlation of several modalities to tackle biomedical research questions holistically and across multiple scales. Correlated Multimodal Imaging (CMI) gathers information about exactly the same specimen with two or more complementary modalities that-in combination-create a composite and complementary view of the sample (including insights into structure, function, dynamics and molecular composition). CMI allows to describe biomedical processes within their overall spatio-temporal context and gain a mechanistic understanding of cells, tissues, diseases or organisms by untangling their molecular mechanisms within their native environment. The two best-established CMI implementations for small animals and model organisms are hardware-fused platforms in preclinical imaging (Hybrid Imaging) and Correlated Light and Electron Microscopy (CLEM) in biological imaging. Although the merits of Preclinical Hybrid Imaging (PHI) and CLEM are well-established, both approaches would benefit from standardization of protocols, ontologies and data handling, and the development of optimized and advanced implementations. Specifically, CMI pipelines that aim at bridging preclinical and biological imaging beyond CLEM and PHI are rare but bear great potential to substantially advance both bioimaging and biomedical research. CMI faces three mai

Sites of strong Rec12/Spo11 binding in the fission yeast genome are associated with meiotic recombination and with centromeres

Meiotic recombination arises from Rec12/Spo11-dependent formation of DNA double-strand breaks (DSBs) and their subsequent repair. We identified Rec12-binding peaks across the S. pombe genome using chromatin immunoprecipitation after reversible formaldehyde cross-linking combined with whole-genome DNA microarrays. Strong Rec12-binding coincided with previously identified DSBs at the recombination hotspots ura4A, mbs1, and mbs2, and correlated with DSB formation at a new site. In addition, Rec12-binding corresponded to eight novel conversion hotspots and correlated with crossover density in segments of chromosome I. Notably, Rec12-binding inversely correlated with GC content, contrary to findings in S. cerevisiae. Although both replication origins and Rec12-binding sites preferred AT-rich gene-free regions, they seemed to exclude each other. We also uncovered a connection between binding sites of Rec12 and meiotic cohesin Rec8. Rec12-binding peaks lay often within 2.5 kb of a Rec8-binding peak. Rec12-binding showed preference for large intergenic regions and was found to bind preferentially near to genes expressed strongly in meiosis. Surprisingly, Rec12-binding was also detected in centromeric core regions, which raises the intriguing possibility that Rec12 plays additional roles in meiotic chromosome dynamics