1,720,992 research outputs found
Cryptococcus neoformans typing by PCR fingerprinting using (GACA)4 primers based on C. neoformans genome project data
No full textFour (GACA)(4) PCR fingerprinting sequences, used as markers to identify serotypes A and D and AD hybrids, were retrieved in four Cryptococcus neoformans genome databases. Their locations, both in serotype A and D genomes, were confirmed by chromosomal hybridization with specific probes. Two sequences were recognized to code for hypothetical functional proteins
Mechanisms controlling the integrity of replicating chromosomes in budding yeast
No full textCells are continually challenged by genomic insults that originate from chemical and physical agents diffused in the environment, but also normal cellular metabolism produces genotoxic effects. Moreover, DNA replication and recombination generate intermediates potentially dangerous for genome stability. Growing evidence show that many genetic disorders are characterized by high levels of chromosome alterations due to genomic instability, which is also a hallmark of cancer cells. Recent work shed some light on the molecular events that maintain the integrity of chromosomes during unperturbed S phase and in the face of odds
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Role of homologous recombination in trabectedin-induced DNA damage
No full textTrabectedin (ET-743, Yondelis) is a natural marine compound with antitumour activity currently undergoing phase II/III clinical trials. The mechanism of the drug’s action is still to be defined, even though it has been clearly demonstrated the key role of Nucleotide Excision Repair (NER). To get further insights into the drug’s mode of action, we studied the involvement of the DNA-double strand break repair (DNA-DSB) pathways: homologous and non-homologous recombination, both in budding yeasts and in mammalian cells and the possible cross-talk between NER and these repair pathways. Budding yeasts and mammalian cells deficient in the non-homologous end-joining pathway were moderately sensitive to trabectedin, while systems deficient in the homologous recombination pathway were extremely sensitive to the drug, with a 100-fold decrease in the IC50, suggesting that trabectedin-induced lesions are repaired by this pathway. The induction of Rad51 foci and the appearance of γ-H2AX were chosen as putative markers for DNA-DSBs and were studied at different time points after trabectedin treatment in NER proficient and deficient systems. Both were clearly detected only in the presence of an active NER, suggesting that the DSBs are not directly caused by the drug, but are formed during the processing/repair of the drug- induced lesions
Srs2 and Sgs1 DNA helicases associate with mrell in different subcomplexes following checkpoint activation and CDK1-mediated Srs2 phosphorylation
No full textMutations in the genes encoding the BLM and WRN RecQ DNA helicases and the MRE11-RAD50-NBS1 complex lead to genome instability and cancer predisposition syndromes. The Saccharomyces cerevisiae Sgs1 RecQ helicase and the Mre11 protein, together with the Srs2 DNA helicase, prevent chromosome rearrangements and are implicated in the DNA damage checkpoint response and in DNA recombination. By searching for Srs2 physical interactors, we have identified Sgs1 and Mre11. We show that Srs2, Sgs1, and Mre11 form a large complex, likely together with yet unidentified proteins. This complex reorganizes into Srs2-Mre11 and Sgs1-Mre11 subcomplexes following DNA damage-induced activation of the Mec1 and Tell checkpoint kinases. The defects in subcomplex formation observed in mec1 and tel1 cells can be recapitulated in srs2-7AV mutants that are hypersensitive to intra-S DNA damage and are altered in the DNA damage-induced and Cdk1-dependent phosphorylation of Srs2. Altogether our observations indicate that Mec1- and Tel1-dependent checkpoint pathways modulate the functional interactions between Srs2, Sgs1, and Mrel1 and that the Srs2 DNA helicase represents an important target of the Cdk1-mediated cellular response induced by DNA damage
Sen1/SETX helicase limits DNA:RNA hybrids at DNA double strand breaks and determines faithful repair through end joining and homologous recombination
No full textThe repair of DNA double strand breaks (DSB) through non-homologous end joining (NHEJ) or homologous recombination (HR) is a finely regulated process. Genetic and molecular impedances in either of the pathways affect the fate of the DSB repair and can lead to extended chromosome rearrangements, triggering inheritable genetic instability and tumorigenesis.
Recent findings indicated that formation of DNA:RNA hybrids at DSB sites might interfere with DSB repair and DNA damage response. Here we characterized the role of budding yeast DNA:RNA helicase Sen1, orthologous of the human Senataxin/SETX, in DSB repair. Chromatin immunoprecipitation analyses showed that Sen1 is recruited to one HO-induced DSB, contributing to remove DNA:RNA hybrids nearby the lesion. Along with the increased DNA:RNA hybrids, the binding of Rpb3, a subunit of the RNA polymerase II complex, is also prolonged in Sen1-depleted cells. Remarkably, the persistent DNA:RNA hybrids cause abrupt Mre11 and Dna2 dependent resection of the DSB, in the absence of Sen1. By specific genetic backgrounds, we found that Sen1 depletion leads to faster ectopic recombination repair of a DSB and, surprisingly, to elevated NHEJ and chromosome translocations. In line with the increased NHEJ, KU binding at the DSB is also prolonged in Sen1-depleted cells.
In summary, our data suggest molecular mechanism through which Sen1 removes DNA:RNA hybrids at DSB in order to prevent non-canonical resection initiation, also limiting KU persistence at DSB and dangerous NHEJ events. We believed that these results in yeast might contribute to explain molecularly pathologic phenotypes, recently described in human cells depleted of Senataxin
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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