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https://www.readbyqxmd.com/read/29158515/a-programmed-cell-division-delay-preserves-genome-integrity-during-natural-genetic-transformation-in-streptococcus-pneumoniae
#1
Matthieu J Bergé, Chryslène Mercy, Isabelle Mortier-Barrière, Michael S VanNieuwenhze, Yves V Brun, Christophe Grangeasse, Patrice Polard, Nathalie Campo
Competence for genetic transformation is a differentiation program during which exogenous DNA is imported into the cell and integrated into the chromosome. In Streptococcus pneumoniae, competence develops transiently and synchronously in all cells during exponential phase, and is accompanied by a pause in growth. Here, we reveal that this pause is linked to the cell cycle. At least two parallel pathways impair peptidoglycan synthesis in competent cells. Single-cell analyses demonstrate that ComM, a membrane protein induced during competence, inhibits both initiation of cell division and final constriction of the cytokinetic ring...
November 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/29153323/microtubule-tip-tracking-by-the-spindle-and-kinetochore-protein-ska1-requires-diverse-tubulin-interacting-surfaces
#2
Julie K Monda, Ian P Whitney, Ekaterina V Tarasovetc, Elizabeth Wilson-Kubalek, Ronald A Milligan, Ekaterina L Grishchuk, Iain M Cheeseman
The macromolecular kinetochore functions to generate interactions between chromosomal DNA and spindle microtubules [1]. To facilitate chromosome movement and segregation, kinetochores must maintain associations with both growing and shrinking microtubule ends. It is critical to define the proteins and their properties that allow kinetochores to associate with dynamic microtubules. The kinetochore-localized human Ska1 complex binds to microtubules and tracks with depolymerizing microtubule ends [2]. We now demonstrate that the Ska1 complex also autonomously tracks with growing microtubule ends in vitro, a key property that would allow this complex to act at kinetochores to mediate persistent associations with dynamic microtubules...
November 9, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/29150593/rapid-and-efficient-crispr-cas9-based-mating-type-switching-of-saccharomyces-cerevisiae
#3
Ze-Xiong Xie, Leslie A Mitchell, Hui-Min Liu, Bing-Zhi Li, Duo Liu, Neta Agmon, Yi Wu, Xia Li, Xiao Zhou, Bo Li, Wen-Hai Xiao, Ming-Zhu Ding, Ying Wang, Ying-Jin Yuan, Jef D Boeke
Rapid and highly efficient mating-type switching of Saccharomyces cerevisiae enables a wide variety of genetic manipulations such as the construction of strains, for instance isogenic haploid pairs of both mating-types, diploids and polyploids. We used the CRISPR/Cas9 system to generate a double-strand break (DSB) at the MAT locus, and in a single co-transformation, both haploid and diploid cells were switched to the specified mating-type at ~80% efficiency. The mating-type of strains carrying either rod or ring chromosome III were switched, including those lacking HMLα and HMRa cryptic mating loci...
November 17, 2017: G3: Genes—Genomes—Genetics
https://www.readbyqxmd.com/read/29150513/high-prevalence-and-genetic-diversity-of-large-phicd211-phicdif1296t-like-prophages-in-clostridioides-difficile
#4
Julian R Garneau, Ognjen Sekulovic, Bruno Dupuy, Olga Soutourina, Marc Monot, Louis-Charles Fortier
Clostridioides difficile (formerly Clostridium difficile) is a pathogenic bacterium displaying great genetic diversity. A significant proportion of this diversity is due to the presence of integrated prophages. Here, we provide an in-depth analysis of phiCD211, also known as phiCDIF1296T, the largest phage identified in C. difficile so far, with a genome of 131-kbp. It shares morphological and genomic similarity with other large siphophages like phage 949 infecting Lactococcus lactis and phage c-st infecting Clostridium botulinum...
November 17, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29146911/cytokinesis-requires-localized-%C3%AE-actin-filament-production-by-an-actin-isoform-specific-nucleator
#5
A Chen, P D Arora, C A McCulloch, A Wilde
Cytokinesis is initiated by the localized assembly of the contractile ring, a dynamic actomyosin structure that generates a membrane furrow between the segregating chromosomal masses to divide a cell into two. Here we show that the stabilization and organization of the cytokinetic furrow is specifically dependent on localized β-actin filament assembly at the site of cytokinesis. β-actin filaments are assembled directly at the furrow by an anillin-dependent pathway that enhances RhoA-dependent activation of the formin DIAPH3, an actin nucleator...
November 16, 2017: Nature Communications
https://www.readbyqxmd.com/read/29141250/a-small-supernumerary-marker-derived-from-the-pericentromeric-region-of-chromosome-5-case-report-and-delineation-of-partial-trisomy-5p-phenotype
#6
Letizia Camerota, Mariabernarda Pitzianti, Diana Postorivo, Anna M Nardone, Claudio Ligas, Costanzo Moretti, Augusto Pasini, Francesco Brancati
A 17-year-old girl presented with a distinct phenotype mainly featuring craniofacial dysmorphism, including a disproportioned large, round, elongated face; hypertelorism; deep-set eyes with short palpebral fissures; obesity (BMI 37), and a neuropsychiatric disorder with high-functioning autism. Postnatal conventional cytogenetic analyses from peripheral blood revealed a mosaic small supernumerary marker chromosome (sSMC) with a mos 47,XX,+mar[7]/46,XX[43] karyotype. By cenM-FISH technique, the sSMC was identified as a ring derivative of chromosome 5...
November 16, 2017: Cytogenetic and Genome Research
https://www.readbyqxmd.com/read/29140466/transcription-induced-supercoiling-as-the-driving-force-of-chromatin-loop-extrusion-during-formation-of-tads-in-interphase-chromosomes
#7
Dusan Racko, Fabrizio Benedetti, Julien Dorier, Andrzej Stasiak
Using molecular dynamics simulations, we show here that growing plectonemes resulting from transcription-induced supercoiling have the ability to actively push cohesin rings along chromatin fibres. The pushing direction is such that within each topologically associating domain (TAD) cohesin rings forming handcuffs move from the source of supercoiling, constituted by RNA polymerase with associated DNA topoisomerase TOP1, towards borders of TADs, where supercoiling is released by topoisomerase TOPIIB. Cohesin handcuffs are pushed by continuous flux of supercoiling that is generated by transcription and is then progressively released by action of TOPIIB located at TADs borders...
November 13, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/29119272/interaction-of-the-saccharomyces-cerevisiae-ring-domain-protein-nse1-with-nse3-and-the-smc5-6-complex-is-required-for-chromosome-replication-and-stability
#8
Saima Wani, Neelam Maharshi, Deepash Kothiwal, Lakshmi Mahendrawada, Raju Kalaivani, Shikha Laloraya
Genomic stability is maintained by the concerted actions of numerous protein complexes that participate in chromosomal duplication, repair, and segregation. The Smc5/6 complex is an essential multi-subunit complex crucial for repair of DNA double-strand breaks. Two of its subunits, Nse1 and Nse3, are homologous to the RING-MAGE complexes recently described in human cells. We investigated the contribution of the budding yeast Nse1 RING-domain by isolating a mutant nse1-103 bearing substitutions in conserved Zinc-coordinating residues of the RING-domain that is hypersensitive to genotoxic stress and temperature...
November 8, 2017: Current Genetics
https://www.readbyqxmd.com/read/29118001/real-time-detection-of-condensin-driven-dna-compaction-reveals-a-multistep-binding-mechanism
#9
Jorine M Eeftens, Shveta Bisht, Jacob Kerssemakers, Marc Kschonsak, Christian H Haering, Cees Dekker
Condensin, a conserved member of the SMC protein family of ring-shaped multi-subunit protein complexes, is essential for structuring and compacting chromosomes. Despite its key role, its molecular mechanism has remained largely unknown. Here, we employ single-molecule magnetic tweezers to measure, in real time, the compaction of individual DNA molecules by the budding yeast condensin complex. We show that compaction can proceed in large steps, driving DNA molecules into a fully condensed state against forces of up to 2 pN...
November 8, 2017: EMBO Journal
https://www.readbyqxmd.com/read/29090019/molecular-characterization-and-evaluation-of-complex-rearrangements-in-a-case-of-ring-chromosome-15
#10
Stuti Tewari, Naznin Lubna, Raju Shah, Ahmed B H Al-Rikabi, Krati Shah, Jayesh Sheth, Frenny Sheth
BACKGROUND: Ring chromosome 15 is a rare genetic entity. Only a few cases have been reported with characterization using molecular techniques. The clinical presentation is quite variable, as a result of differences in the breakpoints, haploinsufficiency of genes involved in deleted segment/s, level of mosaicism and ring instability resulting in a variability of rearrangement of genetic material. CASE PRESENTATION: The proband, a 2 months old boy, presented with small head size and facial dysmorphism...
2017: Molecular Cytogenetics
https://www.readbyqxmd.com/read/29080333/aneurysmal-bone-cysts-and-pathologic-fracture-associated-with-supernumerary-ring-chromosome-6-in-two-unrelated-patients
#11
Lauren M Hurd, Mihir M Thacker, Ericka Okenfuss, Angela L Duker, Yang Lou, Mary P Harty, Katrina Conard, Jane B Lian, Michael B Bober
Small supernumerary ring chromosome 6 (sSRC[6]) is a rare chromosomal abnormality characterized by a broad clinical phenotype. The spectrum of this disorder can range from phenotypically normal to severe developmental delay and congenital anomalies. We describe two unrelated patients with small SRCs derived from chromosome 6 with a novel bone phenotype. Both patients presented with a complex bone disorder characterized by severe osteopenia, pathologic fractures, and cyst-like lesions within the bone. Imaging revealed decreased bone mineral density, mutiple multiloculated cysts and cortical thinning...
December 2017: American Journal of Medical Genetics. Part A
https://www.readbyqxmd.com/read/29063501/the-normality-of-sperm-in-an-infertile-man-with-ring-chromosome-15-a-case-report
#12
Kazuyo Nishikawa, Fumiaki Itoi, Miki Nagahara, Mami Jose, Ayumi Matsunaga, Jun Ueda, Takashi Iwamoto
PURPOSE: The purpose of this report is to analyze the chromosome status and fertilization capability of sperm obtained from an infertile male patient with ring chromosome 15. METHODS: This was a case report at a private in vitro fertilization clinic. A man diagnosed with severe oligozoospermia carrying ring chromosome 15. To evaluate the chromosome status and fertilization capability, sperm from a patient carrying ring chromosome 15 were injected into enucleated mouse oocytes...
October 23, 2017: Journal of Assisted Reproduction and Genetics
https://www.readbyqxmd.com/read/28962153/turner-syndrome-caused-by-rare-complex-structural-abnormalities-involving-chromosome-x
#13
Niu Li, Li Zhao, Juan Li, Yu Ding, Yongnian Shen, Xiaodong Huang, Xiumin Wang, Jian Wang
Turner syndrome (TS) is a phenotypic heterogeneous genetic disorder caused by the loss of an X-chromosome or X-structural abnormalities in the X-chromosome, and affects approximately 1 in every 2,500 females. The affected individuals may develop diverse clinical features, including short stature, ovarian dysgenesis, skeletal dysplasia, facial abnormalities and other disorders. A constitutional karyotype of 45, X accounts for nearly 50% of TS patients, while X-mosaicism and other X-chromosomal structural abnormalities, including deletions, duplications, ring, isodicentric chromosomes, inversions and translocations, have been reported in other cases...
September 2017: Experimental and Therapeutic Medicine
https://www.readbyqxmd.com/read/28941966/otologic-disorders-in-turner-syndrome
#14
E Bois, M Nassar, D Zenaty, J Léger, T Van Den Abbeele, N Teissier
INTRODUCTION: Patients with Turner syndrome (TS) have craniofacial malformations, such as Eustachian tube hypoplasia and dysfunction and velar dysfunction, which foster acute otitis media. The aim of this study was to inventory pediatric otologic disorders in patients with TS at their first ENT consultation in our center. PATIENTS AND METHODS: We reviewed the ENT consultation data of pediatric TS patients followed in our center between 2005 and 2015: otoscopy, hearing threshold, and history of acute otitis media or ENT surgery...
September 20, 2017: European Annals of Otorhinolaryngology, Head and Neck Diseases
https://www.readbyqxmd.com/read/28938124/the-kinetochore-receptor-for-the-cohesin-loading-complex
#15
Stephen M Hinshaw, Vasso Makrantoni, Stephen C Harrison, Adèle L Marston
The ring-shaped cohesin complex brings together distant DNA domains to maintain, express, and segregate the genome. Establishing specific chromosomal linkages depends on cohesin recruitment to defined loci. One such locus is the budding yeast centromere, which is a paradigm for targeted cohesin loading. The kinetochore, a multiprotein complex that connects centromeres to microtubules, drives the recruitment of high levels of cohesin to link sister chromatids together. We have exploited this system to determine the mechanism of specific cohesin recruitment...
September 21, 2017: Cell
https://www.readbyqxmd.com/read/28936767/smc-complexes-orchestrate-the-mitotic-chromatin-interaction-landscape
#16
REVIEW
Yasutaka Kakui, Frank Uhlmann
Chromatin is a very long DNA-protein complex that controls the expression and inheritance of the genetic information. Chromatin is stored within the nucleus in interphase and further compacted into chromosomes during mitosis. This process, known as chromosome condensation, is essential for faithful segregation of genomic DNA into daughter cells. Condensin and cohesin, members of the structural maintenance of chromosomes (SMC) family, are fundamental for chromosome architecture, both for establishment of chromatin structure in the interphase nucleus and for the formation of condensed chromosomes in mitosis...
September 21, 2017: Current Genetics
https://www.readbyqxmd.com/read/28931593/active-ran-regulates-anillin-function-during-cytokinesis
#17
Daniel Beaudet, Tara Akhshi, Julia Phillipp, Christopher Law, Alisa Piekny
Cytokinesis cleaves a cell into two daughters at the end of mitosis, and must be spatially coordinated with chromosome segregation to prevent aneuploidy. The dogma is that the mitotic spindle governs the assembly and constriction of an actomyosin ring. Here, we reveal a function for active Ran in spatially restricting the ring. Our model is that during anaphase, "free" importins, whose gradient inversely correlates with active Ran and chromatin position, function as a molecular ruler for the recruitment and localization of anillin, a contractile protein and a crucial regulator of cytokinesis...
November 15, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28930671/cohesin-can-remain-associated-with-chromosomes-during-dna-replication
#18
James D P Rhodes, Judith H I Haarhuis, Jonathan B Grimm, Benjamin D Rowland, Luke D Lavis, Kim A Nasmyth
To ensure disjunction to opposite poles during anaphase, sister chromatids must be held together following DNA replication. This is mediated by cohesin, which is thought to entrap sister DNAs inside a tripartite ring composed of its Smc and kleisin (Scc1) subunits. How such structures are created during S phase is poorly understood, in particular whether they are derived from complexes that had entrapped DNAs prior to replication. To address this, we used selective photobleaching to determine whether cohesin associated with chromatin in G1 persists in situ after replication...
September 19, 2017: Cell Reports
https://www.readbyqxmd.com/read/28928399/a-ring-polymer-model-shows-how-macromolecular-crowding-controls-chromosome-arm-organization-in-escherichia-coli
#19
Chanil Jeon, Youngkyun Jung, Bae-Yeun Ha
Macromolecular crowding influences various cellular processes such as macromolecular association and transcription, and is a key determinant of chromosome organization in bacteria. The entropy of crowders favors compaction of long chain molecules such as chromosomes. To what extent is the circular bacterial chromosome, often viewed as consisting of "two arms", organized entropically by crowding? Using computer simulations, we examine how a ring polymer is organized in a crowded and cylindrically-confined space, as a coarse-grained bacterial chromosome...
September 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28914604/scc2-nipbl-hops-between-chromosomal-cohesin-rings-after-loading
#20
James Rhodes, Davide Mazza, Kim Nasmyth, Stephan Uphoff
The cohesin complex mediates DNA-DNA interactions both between (sister chromatid cohesion) and within chromosomes (DNA looping). It has been suggested that intra-chromosome loops are generated by extrusion of DNAs through the lumen of cohesin's ring. Scc2 (Nipbl) stimulates cohesin's ABC-like ATPase and is essential for loading cohesin onto chromosomes. However, it is possible that the stimulation of cohesin's ATPase by Scc2 also has a post-loading function, for example driving loop extrusion. Using fluorescence recovery after photobleaching (FRAP) and single-molecule tracking in human cells, we show that Scc2 binds dynamically to chromatin, principally through an association with cohesin...
September 15, 2017: ELife
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