Popular Political Agency in Byzantium's villages and towns

Αν και η σύγχρονη έρευνα για την βυζαντινή δημοκρατία παρουσιάζει την Κωνσταντινούπολη ως κόμβο μιας πολυσύνθετης και πολυφωνικής πολιτικής, πολύ λιγότερο έχει ερευνηθεί η κοινωνική και πολιτική ταυτότητα των μικρότερων οικισμών της αυτοκρατορίας. Θέμα του άρθρου είναι αυτός ο εκτενέστερος κόσμος χωριών και πόλεων της περιφέρειας και η σχέση τους με τον «ρωμαϊκό» κόσμο γύρω τους κατά τη διάρκεια της μεσοβυζαντινής περιόδου. Διερευνάται η στάση του χωριού και της πόλης απέναντι στην εξουσία και εντοπίζονται διάφορα στοιχεία συλλογικής δράσης, τα οποία μπορούν να χαρακτηρίζονται ως «πολιτική δραστηριότητα».Αν και η σύγχρονη έρευνα για την βυζαντινή δημοκρατία παρουσιάζει την Κωνσταντινούπολη ως κόμβο μιας πολυσύνθετης και πολυφωνικής πολιτικής, πολύ λιγότερο έχει ερευνηθεί η κοινωνική και πολιτική ταυτότητα των μικρότερων οικισμών της αυτοκρατορίας. Θέμα του άρθρου είναι αυτός ο εκτενέστερος κόσμος χωριών και πόλεων της περιφέρειας και η σχέση τους με τον «ρωμαϊκό» κόσμο γύρω τους κατά τη διάρκεια της μεσοβυζαντινής περιόδου. Διερευνάται η στάση του χωριού και της πόλης απέναντι στην εξουσία και εντοπίζονται διάφορα στοιχεία συλλογικής δράσης, τα οποία μπορούν να χαρακτηρίζονται ως «πολιτική δραστηριότητα»

Studying the beginning of the end: The roles of Tbf1 and Reb1 at subtelomeres

Abstract: Telomeres protect the ends of linear chromosomes from being recognized as DNA breaks, helping to avoid events that could lead to genomic instability. The telomeric sequences in budding yeast recruit a multitude of proteins in order to carry out essential functions in end replication and protection from DNA repair machinery. However, there is evidence that subtelomeres, which lie directly interior to the telomeric repeats, may also affect the properties of the chromosomal ends. Two of the main proteins recruited to the subtelomeres are Tbf1 and Reb1. While they bind at promoter regions of a multitude of genes, their function at the chromosomal ends is still unclear. TBF1 and REB1 are both essential genes, with some overlapping targets and functions in fine tuning transcription and creating nucleosome free regions. Past work suggests both Tbf1 and Reb1 could have roles in telomere length maintenance and limiting the spread of telomere silencing. As many of these studies were done in the absence of subtelomeric regions, or with mutant alleles, it is unclear if the telomere phenotypes observed stem from changes in the subtelomere regions or from alterations in transcription of Tbf1 or Reb1 targets. This is evidenced by different studies producing conflicting evidence pertaining to the functions of these proteins. In order to avoid such complications, a system was designed to study the effects of the absence of Tbf1 and Reb1 at subtelomeres with otherwise native structures. Through the use of this system, it was found that Tbf1 and Reb1 may not be very important for telomere length maintenance or limiting the spread of telomere silencing. However, it was discovered that Tbf1 and Reb1 have a role in repressing TERRA, a long non-coding RNA transcribed from the subtelomere and telomeric repeats. Recent work suggests TERRA may have a role in telomere maintenance in the absence of telomerase. However, limiting transcription of the telomere is crucial, as it could lead to replication fork stalling, DNA breaks and genomic instability. This study underlines the importance of working with natural subtelomere regions when studying telomeres and offers a new insight into TERRA regulation.Les séquences télomèriques chez S. cerevisiae recrutent une multitude de protéines afin de remplir ses fonctions essentielles pour le maintien de l’integrité genomique : la réplication complète des chromosomes et la protection des mécanismes de réparation de l'ADN. Cependant, il y a des indices que les régions sous-télomèriques, qui se trouvent directement à l'intérieur des répétitions télomèriques, peuvent aussi affecter les fonctions des extrémités chromosomiques. Deux des principales protéines recrutées aux sous-télomères sont Tbf1 et Reb1. Bien qu'elles se lient aux régions promotrices d'une multitude de gènes, leurs fonctions aux extrémités chromosomiques ne sont pas encore comprises. Des études précédentes suggèrent que Tbf1 et Reb1 pourraient jouer un rôle dans le maintien de la longueur des télomères et en empêcher la propagation de répression transcriptionnel des gènes près des télomères. Comme beaucoup de ces études ont été réalisées en l'absence de régions sous-télomèriques ou avec des allèles mutants, on ne sait pas si les phénotypes observés proviennent de changements dans les régions sous-télomèriques ou des altérations de la transcription des cibles Tbf1 ou Reb1. Afin d'éviter ces complications, un système a été conçu pour étudier les effets de l'absence de Tbf1 et Reb1 des sous- télomères avec des structures naturelles. L'utilisation de ce système a permis de découvrir que, Tbf1 et Reb1 ne sont pas très importantes pour le maintien de la longueur des télomères ou pour limiter la propagation de répression transcriptionnel. Cependant, il a été observé que Tbf1 et Reb1 ont un rôle dans la répression de TERRA, un ARN long non codant transcrit à partir des régions sous-télomèriques. Récemment, il a été suggéré que TERRA pourrait jouer un rôle dans le maintien des télomères. Toutefois, il est crucial de limiter la transcription du télomère, car elle pourrait mener à une cassure de l’ADN et l'instabilité génomique. Cette étude souligne l'importance de travailler avec des régions sous-télomèriques non-modifiées ou modifiées en étudiant les télomères et offre un nouvel aperçu de la régulation de TERRA

Book Review: A. SIMPSON, Niketas Choniates: A Historiographical Study. Oxford Studies in Byzantium

Book Review: A. SIMPSON, Niketas Choniates: A Historiographical Study. Oxford Studies in Byzantiumpp. 400  | 2 in-text maps  | 978-0-19-967071-0 | Oxford 201

The Outsider's Gaze: Reflections on recent non-Byzantinist Readings of Byzantine History and on their Implications for our Field

The present essay reviews recent work on Byzantium, its politics, religion, and culture published outside the world of Byzantine Studies and discusses the significance of such readings for the evolving relationship of our field with audiences both lay and academic.The present essay reviews recent work on Byzantium, its politics, religion, and culture published outside the world of Byzantine Studies and discusses the significance of such readings for the evolving relationship of our field with audiences both lay and academic

Book Review: A. SIMPSON, Niketas Choniates: A Historiographical Study. Oxford Studies in Byzantium

Book Review: A. SIMPSON, Niketas Choniates: A Historiographical Study. Oxford Studies in Byzantiumpp. 400  | 2 in-text maps  | 978-0-19-967071-0 | Oxford 201

Telomerase in Space and Time: Regulation of Yeast Telomerase Function at Telomeres and DNA Breaks

A development of new strategies against telomerase-associated disorders, such as dyskeratosis congenita, aplastic anemia or cancer, relies on a detailed understanding of telomerase life cycle and the multiple layers of its regulation. Saccharomyces cerevisiae is a prime model to study telomerase function and it has already revealed many conserved pathways for telomerase biology. In this chapter, we review the current knowledge of the regulatory pathways that control telomerase function in budding yeast. In particular, we discuss the cell cycle-dependent assembly of telomerase and its recruitment to telomeres. We also focus on the mechanisms that target telomerase to short telomeres. Finally, we discuss possible pathways that inhibit telomerase function at DNA double-strand breaks, thus limiting deleterious de novo telomere addition events

Isolation and identification of Beta-Lactam Producing Microorganisms using PCR based methodologies

The polymerase chain reaction (PCR) was investigated as a potential tool in microbial screening for 13-lactam. producing organisms. Optimization of PCR conditions and the addition of acetamide to the PCR reaction allowed for the successful amplification of the isopenicillin N synthetase (lPNS) gene in S. clavuligerus, S. tanashiensis, S. griseus, S. olivaceus, S. lipmanii, and S. chartreusis. PCR was used to produce a radiolabelled probe from S. clavuligerus that was used to detect analogous genes in bacteria and fungi. Southern blot and dot blot analysis using the lPNS probe revealed the presence of IPNS-like sequences in seventeen organisms. Fourteen of these sequences belonged to known 13-lactam. producing organisms; one unidentified soil isolate; and two non-/3-lactam. producing organisms viz. S. venezuelae ATCC 10712 and S. hygroscopicus ATCC 21703. The lPNS gene was also detected in a 13-lactam producer (S. chartreusis) that had lost its ability to produce antibiotic. It would therefore have been overlooked in a conventional antibiotic screening program. The use of PCR, coupled with Southern hybridization and dot blot analysis, increased the sensitivity and specificity of the antibiotic screening procedures and allowed for the investigation of evolutionary relationships between the eukaryotes and the prokaryotes. A preliminary investigation into the potential use of RAPD PCR and protein fmgerprinting as tools for solving discrepancies in streptomycete identification was conducted. A variety of streptomycete species that were chosen as being representative of a number of numerical taxonomic classes were amplified using various RAPD primers. Streptomycetes appear to be genetically diverse organisms as was reflected by their RAPD and protein profiles. The application of PCR in an antibiotic screening program showed great potential as a specific and sensitive tool in the detection of /3-lactam producers and in the elimination of duplicate strains

From reactor to rheology in industrial polymers

This article reviews current efforts towards quantitative prediction of rheological properties of industrial polymer resins, based upon their polydisperse branched molecular structure. This involves both an understanding of how reactor and reaction conditions influence the distribution of chain lengths and branch placement (which is the province of reactor engineering) and an understanding of how the molecular structures in turn give rise to the rheology (the province of polymer physics). Both fields are reviewed at an introductory level, focussing in particular on developments in theoretical prediction of rheology for both entangled model polymers and industrial polymers. Finally, we discuss three classes of reaction for which the fields of reactor engineering and polymer physics have been truly combined to produce predictions from reactor to rheology

High energy ignition systems

Imperial Users onl