Anatomy of mouse recombination hot spots

Genome-wide analyses have suggested thousands of meiotic recombination hot spots across mammalian genomes. However, very few hot spots have been directly analyzed at a sub-kb scale for crossover (CO) activity. Using recombinant inbred strains as a CO library, here we report the identification and detailed characterization of seven new meiotic hot spots on mouse chromosome 19, more than doubling the number of currently available mouse hot spots. Although a shared feature is the narrow 1.5–2.5-kb width of these recombinogenic sites, these analyses revealed that hot spots have diverse sequence attributes and distinct symmetric and asymmetric CO profiles. Interestingly, CO molecules with discontinuous conversion tracts are commonly observed, contrasting with those found in human. Furthermore, unlike human hot spots, those present in the mouse do not necessarily have a quasi-normal CO distribution but harbor CO repulsion zones within recombinogenic cores. We propose a model where local chromatin landscape directs these repulsion zones

Analysis of Biological Features Associated with Meiotic Recombination Hot and Cold Spots in Saccharomyces cerevisiae

Meiotic recombination is not distributed uniformly throughout the genome. There are regions of high and low recombination rates called hot and cold spots, respectively. The recombination rate parallels the frequency of DNA double-strand breaks (DSBs) that initiate meiotic recombination. The aim is to identify biological features associated with DSB frequency. We constructed vectors representing various chromatin and sequence-based features for 1179 DSB hot spots and 1028 DSB cold spots. Using a feature selection approach, we have identified five features that distinguish hot from cold spots in Saccharomyces cerevisiae with high accuracy, namely the histone marks H3K4me3, H3K14ac, H3K36me3, and H3K79me3; and GC content. Previous studies have associated H3K4me3, H3K36me3, and GC content with areas of mitotic recombination. H3K14ac and H3K79me3 are novel predictions and thus represent good candidates for further experimental study. We also show nucleosome occupancy maps produced using next generation sequencing exhibit a bias at DSB hot spots and this bias is strong enough to obscure biologically relevant information. A computational approach using feature selection can productively be used to identify promising biological associations. H3K14ac and H3K79me3 are novel predictions of chromatin marks associated with meiotic DSBs. Next generation sequencing can exhibit a bias that is strong enough to lead to incorrect conclusions. Care must be taken when interpreting high throughput sequencing data where systematic biases have been documented

Gestaltung einer haptischen Navigationshilfe für den mobilen Bereich

Dieser Beitrag beschreibt relevante Arbeitsergebnisse bezüglich des Konzepts eines haptischen User Interfaces, das im Rahmen des EU-Projektes ASK-IT angefertigt wurde. Es wurde eine mobile haptische Navigationshilfe für Blinde konzipiert, ein Prototyp entwickelt und dieser in Nutzertests evaluiert. Das System basiert auf einem vibrotaktilen Multidisplay als Interaktionsschnittstelle, welches an den Handgelenken des Nutzers angebracht wird. Der Ursprung des Konzepts liegt in der Unzulänglichkeit vieler existierender mobiler Navigationsgeräte, die auschließlich den visuellen und auditiven Sinneskanal ansprechen, obwohl beide im Nutzungskontext des Fußgängers der Gefahr der Reizüberflutung ausgesetzt sind. Für die Erarbeitung der haptischen Schnittstelle wurden Designguidelines zusammengetragen, welche auch bei der Entwicklung Anwendung fanden. Die Ergebnisse des Projektes zeigen eine prinzipiell gute Erfolgschance einer derartigen haptischen Interaktionsschnittstelle - und das auch über die Zielgruppe der visuell beeinträchtigten Nutzer hinaus