scholarly journals High-Resolution Mapping of Changes in Histone-DNA Contacts of Nucleosomes Remodeled by ISW2

2002 ◽  
Vol 22 (21) ◽  
pp. 7524-7534 ◽  
Author(s):  
Stefan R. Kassabov ◽  
Nathalia M. Henry ◽  
Martin Zofall ◽  
Toshio Tsukiyama ◽  
Blaine Bartholomew
Keyword(s):  
The Novel ◽  
Histone Fold ◽  
Histone Octamer ◽  
Nucleosome Structure ◽  
High Resolution Mapping ◽  
Nucleosomal Dna ◽  
Before And After ◽  
Resolution Mapping ◽  
A Site ◽  
Dna Template

ABSTRACT The imitation switch (ISWI) complex from yeast containing the Isw2 and Itc1 proteins was shown to preferentially slide mononucleosomes with as little as 23 bp of linker DNA from the end to the center of DNA. The contacts of unique residues in the histone fold regions of H4, H2B, and H2A with DNA were determined with base pair resolution before and after chromatin remodeling by a site-specific photochemical cross-linking approach. The path of DNA and the conformation of the histone octamer in the nucleosome remodeled or slid by ISW2 were not altered, because after adjustment for the new translational position, the DNA contacts at specific sites in the histone octamer had not been changed. Maintenance of the canonical nucleosome structure after sliding was also demonstrated by DNA photoaffinity labeling of histone proteins at specific sites within the DNA template. In addition, nucleosomal DNA does not become more accessible during ISW2 remodeling, as assayed by restriction endonuclease cutting. ISW2 was also shown to have the novel capability of counteracting transcriptional activators by sliding nucleosomes through Gal4-VP16 bound initially to linker DNA and displacing the activator from DNA.

scholarly journals Nucleosome Remodeling by the Human SWI/SNF Complex Requires Transient Global Disruption of Histone-DNA Interactions

2002 ◽  
Vol 22 (11) ◽  
pp. 3653-3662 ◽  
Author(s):  
Sayura Aoyagi ◽  
Geeta Narlikar ◽  
Chunyang Zheng ◽  
Saïd Sif ◽  
Robert E. Kingston ◽  
...  
Keyword(s):  
Restriction Enzyme ◽  
Atp Hydrolysis ◽  
Dnase I ◽  
Cross Linking ◽  
Dna Interactions ◽  
Nucleosome Remodeling ◽  
Histone Octamer ◽  
Nucleosomal Dna ◽  
Single Cross ◽  
A Site

ABSTRACT We utilized a site-specific cross-linking technique to investigate the mechanism of nucleosome remodeling by hSWI/SNF. We found that a single cross-link between H2B and DNA virtually eliminates the accumulation of stably remodeled species as measured by restriction enzyme accessibility assays. However, cross-linking the histone octamer to nucleosomal DNA does not inhibit remodeling as monitored by DNase I digestion assays. Importantly, we found that the restriction enzyme-accessible species can be efficiently cross-linked after remodeling and that the accessible state does not require continued ATP hydrolysis. These results imply that the generation of stable remodeled states requires at least transient disruption of histone-DNA interactions throughout the nucleosome, while hSWI/SNF-catalyzed disruption of just local histone-DNA interactions yields less-stable remodeled states that still display an altered DNase I cleavage pattern. The implications of these results for models of the mechanism of SWI/SNF-catalyzed nucleosome remodeling are discussed.

scholarly journals Novel noncontact charge density map in the setting of post-atrial fibrillation atrial tachycardias: first experience with the Acutus SuperMap Algorithm

2020 ◽  
Author(s):  
Robbert Ramak ◽  
Gian-Battista Chierchia ◽  
Gaetano Paparella ◽  
Cinzia Monaco ◽  
Vincenzo Miraglia ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
High Resolution ◽  
Charge Density ◽  
Pulmonary Vein ◽  
The Novel ◽  
Mapping Algorithm ◽  
Af Ablation ◽  
High Resolution Mapping ◽  
Resolution Mapping ◽  
The Mean

Abstract Purpose The purpose of this study was to evaluate the safety and feasibility of the new high-resolution mapping algorithm SuperMap (Acutus Medical, CA, USA) in identifying and guiding ablation in the setting of regular atrial tachycardias following index atrial fibrillation (AF) ablation. Methods Seven consecutive patients who underwent a radiofrequency catheter ablation guided by the novel noncontact charge density (CD) SuperMap for atrial tachycardia were prospectively enrolled in our study. Results Arrhythmogenic substrate was identified in all seven patients. Mean number of EGM per map was 5859.7 ± 4348.5 points. Three patients (43%) exhibited focal tachycardia mechanisms in the left atrium, alternating from anteroseptal right superior pulmonary vein (RSPV), posterior in proximity of left inferior pulmonary vein (LIPV), and interarial septum in proximity of fossa ovalis, respectively. Four patients exhibited macroreentrant mechanism. In 3 of these patients, SuperMap detected mitral isthmus-dependent flutters with tachycardia cycle lengths of 240, 270 and 420 ms, respectively. In one patient, the mechanism was a macroreentrant tachycardia with the critical isthmus located between the crista terminalis and atriotomy. The mean ablation time (min) was 18.2 ± 12.5 and the mean procedural duration time was 56.4 ± 12.1 min. No minor or major complications occurred. Conclusion The novel high-resolution mapping algorithm SuperMap proved to be safe, fast, and feasible in identifying and guiding ablation in the setting of regular atrial tachycardias following index AF ablation.

scholarly journals Does BLM helicase unwind nucleosomal DNA?

2009 ◽  
Vol 87 (6) ◽  
pp. 875-882 ◽  
Author(s):  
Satoru Fujimoto ◽  
Miroslav Tomschik ◽  
Jordanka Zlatanova
Keyword(s):  
Auxiliary Function ◽  
Full Length ◽  
Recq Helicases ◽  
Histone Octamer ◽  
Nucleosomal Dna ◽  
Blm Helicase ◽  
Strand Annealing ◽  
Dna Template ◽  
Dna Substrate

RecQ helicases maintain chromosome stability by resolving several highly specific DNA structures. BLM, the protein mutated in Bloom’s syndrome, is a member of the RecQ helicase family, and possesses both DNA-unwinding and strand-annealing activity. In this study, we have investigated the unwinding activity of BLM on nucleosomal DNA, the natural nuclear substrate for the enzyme. We generated a DNA template including a strong nucleosome-positioning sequence flanked by forked DNA, which is reportedly one of the preferred DNA substrates for BLM. BLM did not possess detectable unwinding activity toward the forked DNA substrate. However, the truncated BLM, lacking annealing activity, unwound it partially. In the presence of the single-stranded DNA-binding protein RPA, the unwinding activity of both the full-length and the truncated BLMs was promoted. Next, the histone octamer was reconstituted onto the forked DNA to generate a forked mononucleosome. Full-length BLM did not unwind the nucleosomal DNA, but truncated BLM unwound it partially. The unwinding activity for the mononucleosome was not promoted dramatically with RPA. These results indicate that full-length BLM may require additional factors to unwind nucleosomal DNA in vivo, and that RPA is, on its own, unable to perform this auxiliary function.

More Alike Than Unalike: Cross-language Similarity Influences Novel Word Lexicalization in Bilingual Individuals

2020 ◽  
Author(s):  
Pauline Palma ◽  
Marie-France Marin ◽  
k onishi ◽  
Debra Titone
Keyword(s):  
Lexical Decision ◽  
Lexical Decision Task ◽  
Decision Task ◽  
The Novel ◽  
Lexical Representations ◽  
Before And After ◽  
Word Forms ◽  
Explicit Recognition ◽  
Novel Word Learning ◽  
Cross Language

Although several studies have focused on novel word learning and consolidation in native (presumably monolingual) speakers, less is know about how bilinguals add novel words to their mental lexicon. Here, we trained 33 English-French bilinguals on novel word-forms that were neighbors to “hermit” English words (i.e., words with no existing neighbors). Importantly, these English words varied in terms of orthographic overlap with their French translation equivalent (i.e., cognates vs. noncognates). We measured explicit recognition of the novel neighbors and the interaction between novel neighbors and English words through a lexical decision task, both before and after a sleep interval. In the lexical decision task, we found evidence of immediate facilitation for English words with novel neighbors, and evidence of competition after a sleep interval for cognate words only. These results suggest that higher quality of existing lexical representations predicts an earlier onset for novel word lexicalization.

A CRITICAL ASSESSMENT OF THE NOVEL «ASSEMBLY HALL» BY HERMANN KANT IN THE REUNIFIED GERMANY (AFTER 1991)

2020 ◽  
pp. 144-152
Author(s):  
Rimma Gurevich
Keyword(s):  
Critical Assessment ◽  
The Novel ◽  
Aesthetic Appreciation ◽  
Party Position ◽  
Creative Personality ◽  
Before And After

H. Kant’s novel received a high literary and aesthetic appreciation in criticism and wide recognition by readers. Criticism (before and after the unification of Germany) concerns mainly one aspect viz. authenticity of the events depicted in the novel and the charcters’ images. Opponents argue that Kant’s ideological views, his consistent socialist and party position have prompt him to embellish reality, create simulacra, and the idyllic world of socialist Biedermeyer. The article shows that these assessments ignore the nature of his talent, especially his creative personality peculiarities such as journalistic orientation of the motivated «political» person and writer.

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