Requirement of Replication Checkpoint Protein Kinases Mec1/Rad53 for Postreplication Repair in Yeast

DNA lesions in the template strand block the replication fork. In Saccharomyces cerevisiae, replication through DNA lesions occurs via a Rad6/Rad18-dependent pathway where lesions can be bypassed by the action of translesion synthesis (TLS) DNA polymerases η and ζ or by Rad5-mediated template switching. An alternative Rad6/Rad18-independent but Rad52-dependent template switching pathway can also restore the continuity of the replication fork. The Mec1/Rad53-dependent replication checkpoint plays a crucial role in the maintenance of stable and functional replication forks in yeast cells with DNA damage; however, it has remained unclear which of the lesion bypass processes requires the activation of replication checkpoint-mediated fork stabilization. Here we show that postreplication repair (PRR) of newly synthesized DNA in UV-damaged yeast cells is inhibited in the absence of Mec1 and Rad53 proteins. Since TLS remains functional in cells lacking these checkpoint kinases and since template switching by the Rad5 and Rad52 pathways provides the alternative means of lesion bypass and requires Mec1/Rad53, we infer that lesion bypass by the template switching pathways occurs in conjunction with the replication fork that has been stabilized at the lesion site by the action of Mec1/Rad53-mediated replication checkpoint

Physicians’ clinical prediction of survival in head and neck cancer patients in the palliative phase

Background: The prognosis of patients with incurable head and neck cancer (HNC) is a relevant topic. The mean survival of these patients is 5 months but may vary from weeks to more than 3 years. Discussing the prognosis early in the disease trajectory enables patients to make well-considered end-of-life choices, and contributes to a better quality of life and death. However, physicians often are reluctant to discuss prognosis, partly because of the concern to be inaccurate. This study investigated the accuracy of physicians’ clinical prediction of survival of palliative HNC patients. Methods: This study was part of a prospective cohort study in a tertiary cancer center. Patients with incurable HNC diagnosed between 2008 and 2011 (n = 191), and their treating physician were included. Analyses were conducted between July 2018 and February 2019. Patients’ survival was clinically predicted by their physician ≤3 weeks after disclosure of the palliative diagnosis. The clinical prediction of survival in weeks (CPS) was based on physicians’ clinical assessment of the patient during the outpatient visits. More than 25% difference between the actual survival (AS) and the CPS was regarded as a prediction error. In addition, when the difference between the AS and CPS was 2 weeks or less, this was always considered as correct. Results: In 59% (n = 112) of cases survival was overestimated. These patients lived shorter than predicted by their physician (median AS 6 weeks, median CPS 20 weeks). In 18% (n = 35) of the cases survival was correctly predicted. The remaining 23% was underestimated (median AS 35 weeks, median CPS 20 weeks). Besides the differences in AS and CPS, no other significant differences were found between the three groups. There was worse accuracy when predicting survival closer to death: out of the 66 patients who survived 6 weeks or shorter, survival was correctly predicted in only eight (12%). Conclusion: Physicians tend to overestimate the survival of pal

Replication fork stalling by bulky DNA damage: localization at active origins and checkpoint modulation

The integrity of the genome is threatened by DNA damage that blocks the progression of replication forks. Little is known about the genomic locations of replication fork stalling, and its determinants and consequences in vivo. Here we show that bulky DNA damaging agents induce localized fork stalling at yeast replication origins, and that localized stalling is dependent on proximal origin activity and is modulated by the intra–S–phase checkpoint. Fork stalling preceded the formation of sister chromatid junctions required for bypassing DNA damage. Despite DNA adduct formation, localized fork stalling was abrogated at an origin inactivated by a point mutation and prominent stalling was not detected at naturally-inactive origins in the replicon. The intra–S–phase checkpoint contributed to the high-level of fork stalling at early origins, while checkpoint inactivation led to initiation, localized stalling and chromatid joining at a late origin. Our results indicate that replication forks initially encountering a bulky DNA adduct exhibit a dual nature of stalling: a checkpoint-independent arrest that triggers sister chromatid junction formation, as well as a checkpoint-enhanced arrest at early origins that accompanies the repression of late origin firing. We propose that the initial checkpoint-enhanced arrest reflects events that facilitate fork resolution at subsequent lesions

Helden in der Schule. Akten der Tagung Kloster Banz 2014

Ausgehend von der Feststellung, dass die Integration mittelalterlicher Texte im Deutschunterricht in der Schulpraxis weitgehend ein Desiderat darstellt, präsentierten Beitragende aus Schule und Wissenschaft bei der Tagung „Helden in der Schule“ im Oktober 2014 ihre Projekte und Ideen zu und Erfahrungen mit der Implementation germanistisch-mediävistischer Inhalte im Deutschunterricht. Dabei reichen die Beiträge von allgemeinen Überlegungen zum Nutzen mittelalterlicher Literatur in der Schule über konkrete Unterrichtsentwürfe bis hin zur Umsetzung in der Waldorfschule und der Integration schulbezogener Lehrveranstaltungen in der Universität. Bei aller Verschiedenheit in den Herangehensweisen wird in allen Beiträgen eindrucksvoll deutlich gemacht, dass mittelalterliche Literatur auch im 21. Jahrhundert überaus lohnend in die Unterrichtspraxis einbezogen werden kann.Since medieval texts are not treated enough in school, lecturers working in school and university presented their projects, ideas and experiences concerning the implementation of German-mediavistic contents in German school lessons during the conference “Heroes in School” in October 2014. The topics concern general reflection about the profitability of medieval literature in school, concrete lesson plans, the implementation in Rudolf Steiner schools, the integration of seminars in university that deal with the work in school etc. All articles demonstrate that the integration of medieval literature in school worth the effort – also in the 21st century

A truncated DNA-damage-signaling response is activated after DSB formation in the G1 phase of Saccharomyces cerevisiae

In Saccharomyces cerevisiae, the DNA damage response (DDR) is activated by the spatio-temporal colocalization of Mec1-Ddc2 kinase and the 9-1-1 clamp. In the absence of direct means to monitor Mec1 kinase activation in vivo, activation of the checkpoint kinase Rad53 has been taken as a proxy for DDR activation. Here, we identify serine 378 of the Rad55 recombination protein as a direct target site of Mec1. Rad55-S378 phosphorylation leads to an electrophoretic mobility shift of the protein and acts as a sentinel for Mec1 activation in vivo. A single double-stranded break (DSB) in G1-arrested cells causes phosphorylation of Rad55-S378, indicating activation of Mec1 kinase. However, Rad53 kinase is not detectably activated under these conditions. This response required Mec1-Ddc2 and loading of the 9-1-1 clamp by Rad24-RFC, but not Rad9 or Mrc1. In addition to Rad55–S378, two additional direct Mec1 kinase targets are phosphorylated, the middle subunit of the ssDNA-binding protein RPA, RPA2 and histone H2A (H2AX). These data suggest the existence of a truncated signaling pathway in response to a single DSB in G1-arrested cells that activates Mec1 without eliciting a full DDR involving the entire signaling pathway including the effector kinases

Literarische Strategien narrativer Identitätsbildung. Eine Untersuchung der frühen Chroniken des Deutschen Ordens

Die Untersuchung beschäftigt sich mit den frühen Chroniken des Deutschen Ordens. Es wird danach gefragt, welche Rolle literarische Erzählbausteine, Verweisungen und Zitate bei der chronikalischen Selbstdarstellung der Korporation spielen. Die Bedeutung des literarischen Erzählens für die Konstruktion von ‚Identität‘, so die zu überprüfende Hypothese, erschöpft sich nicht in der passiv-medialen Rolle des bloßen Trägerstoffes für ideologische Konzepte, die bereits vor dem Ereignis des literarischen Erzählens und jenseits davon in ihrer Struktur voll entfaltet sind, vielmehr entwickelt der literarische Text eine beträchtliche Eigendynamik, die nicht durch außerliterarische Entitäten substituiert werden kann