http://biblioteca.universia.net/verColeccion.do?id=4025 Mostrando recursos 1 - 20 de 59,293 es http://biblioteca.universia.net/img/logotipo.jpg http://biblioteca.universia.net/ http://biblioteca.universia.net/ficha.do?id=6947368 Apolipoprotein B (apoB) mRNA editing is a nuclear event that minimally requires the RNA substrate, APOBEC-1 and APOBEC-1 Complementation Factor (ACF). The co-localization of these macro-molecules within the nucleus and the modulation of hepatic apoB mRNA editing activity have been described following a variety of metabolic perturbations, but the mechanism that regulates editosome assembly is unknown. APOBEC-1 was effectively co-immunoprecipitated with ACF from nuclear, but not cytoplasmic ext... Lehmann, David M.; Galloway, Chad A.; Sowden, Mark P.; Smith, Harold C. http://biblioteca.universia.net/ficha.do?id=16417720 DNA polymerase zeta (pol ?) participates in several DNA transactions in eukaryotic cells that increase spontaneous and damage-induced mutagenesis. To better understand this central role in mutagenesis in vivo, here we report the fidelity of DNA synthesis in vitro by yeast pol ? alone and with RFC, PCNA and RPA. Overall, the accessory proteins have little effect on the fidelity of pol ?. Pol ? is relatively accurate for single base insertion/deletion errors. However, the average base substitut... Zhong, Xuejun; Garg, Parie; Stith, Carrie M.; McElhinny, Stephanie A. Nick; Kissling, Grace E.; Burgers, Peter M. J.; Kunkel, Thomas A. http://biblioteca.universia.net/ficha.do?id=17934637 We have developed a genetic system with which to replace oriC+ on the Escherichia coli chromosome with modified oriC sequences constructed on plasmids. Using this system we have demonstrated that chromosomal oriC can tolerate the insertion of a 2 kb fragment at the HindIII site between DnaA boxes R3 and R4, whereas the same insertion completely inactivates cloned oriC. We have further found that although R4 is essential for the origin activity of cloned oriC, cells carrying a deletion of R4 i... Bates, D B; Asai, T; Cao, Y; Chambers, M W; Cadwell, G W; Boye, E; Kogoma, T http://biblioteca.universia.net/ficha.do?id=17940263 Cell cycle checkpoints induced by DNA damage play an integral role in preservation of genomic stability by allowing cells to limit the propagation of deleterious mutations. The retinoblastoma tumor suppressor (RB) is crucial for the maintenance of the DNA damage checkpoint function because it elicits cell cycle arrest in response to a variety of genotoxic stresses. Although sporadic loss of RB is characteristic of most cancers and results in the bypass of the DNA damage checkpoint, the conseq... Bosco, Emily E.; Mayhew, Christopher N.; Hennigan, Robert F.; Sage, Julien; Jacks, Tyler; Knudsen, Erik S. http://biblioteca.universia.net/ficha.do?id=17940264 The five human Rad51 paralogs are suggested to play an important role in the maintenance of genome stability through their function in DNA double-strand break repair. These proteins have been found to form two distinct complexes in vivo, Rad51B–Rad51C–Rad51D–Xrcc2 (BCDX2) and Rad51C–Xrcc3 (CX3). Based on the recent Pyrococcus furiosus Rad51 structure, we have used homology modeling to design deletion mutants of the Rad51 paralogs. The models of the human Rad51B, Rad51C, Xrcc3 and murine Rad51... Miller, Kristi A.; Sawicka, Dorota; Barsky, Daniel; Albala, Joanna S. http://biblioteca.universia.net/ficha.do?id=17940265 Genome sequence data can be used to analyze genome plasticity by whole genome PCR scanning. Small sized chromosomes can indeed be fully amplified by long-range PCR with a set of primers designed using a reference strain and applied to several other strains. Analysis of the resulting patterns can reveal the genome plasticity. To facilitate such analysis, we have developed GenoFrag, a software package for the design of primers optimized for whole genome scanning by long-range PCR. GenoFrag was ... Ben Zakour, Nouri; Gautier, Michel; Andonov, Rumen; Lavenier, Dominique; Cochet, Marie-Françoise; Veber, Philippe; Sorokin, Alexei; Le Loir, Yves http://biblioteca.universia.net/ficha.do?id=17940266 An RNA-dependent association of Ku antigen with nuclear DNA helicase II (NDH II), alternatively named RNA helicase A (RHA), was found in nuclear extracts of HeLa cells by immunoprecipitation and by gel filtration chromatography. Both Ku antigen and NDH II were associated with hnRNP complexes. Two-dimensional gel electrophoresis showed that Ku antigen was most abundantly associated with hnRNP C, K, J, H and F, but apparently not with others, such as hnRNP A1. Unexpectedly, DNA-dependent protei... Zhang, Suisheng; Schlott, Bernhard; Görlach, Matthias; Grosse, Frank http://biblioteca.universia.net/ficha.do?id=17940267 We synthesized a pentamine (3-3-3-3) and two hexamine (3-3-3-3-3 and 3-4-3-4-3) analogues of the natural polyamine, spermine (3-4-3) and studied their effectiveness in condensing pGL3 plasmid DNA, using light scattering and atomic force microscopic (AFM) techniques. The midpoint concentration of the polyamines on pGL3 condensation (EC50) was 11.3, 10.6, 1.5, 0.49 and 0.52 µM, respectively, for 3-4-3, norspermine (3-3-3), 3-3-3-3, 3-3-3-3-3 and 3-4-3-4-3 in 10 mM Na cacodylate buffer. Dynamic ... Vijayanathan, Veena; Thomas, Thresia; Antony, Thomas; Shirahata, Akira; Thomas, T. J. http://biblioteca.universia.net/ficha.do?id=17940268 Telomerase is a ribonucleoprotein reverse transcriptase responsible for the maintenance of one strand of telomere terminal repeats. Telomerase-mediated sequence addition is dictated by a short ‘template’ region of the RNA component. Despite the short template segment, telomerases from many organisms have been shown to mediate the synthesis of long extension products. This synthesis presumably depends on two types of translocation events: simultaneous translocation of the RNA–DNA duplex relati... Bosoy, Dimitry; Lue, Neal F. http://biblioteca.universia.net/ficha.do?id=17940269 The formation of clustered DNA damage sites is a unique feature of ionizing radiation. Recent studies have shown that the repair of lesions within clusters may be compromised, but little is understood about the mutagenic consequences of such damage sites. Using a plasmid-based method, damaged DNA containing uracil positioned at 1–5 bp separations from 8-oxo-7,8-dihydroguanine on the complementary strand was transfected into wild-type Escherichia coli or into strains lacking the DNA glycosylas... Pearson, Colin G.; Shikazono, Naoya; Thacker, John; O’Neill, Peter http://biblioteca.universia.net/ficha.do?id=17940270 The abasic (AP) sites, the major mutagenic and cytotoxic genomic lesions, induced directly by oxidative stress and indirectly after excision of damaged bases by DNA glycosylases, are repaired by AP-endonucleases (APEs). Among two APEs in Saccharomyces cerevisiae, Apn1 provides the major APE activity, and Apn2, the ortholog of the mammalian APE, provides back-up activity. We have cloned apn1 and apn2 genes of Schizosaccharomyces pombe, and have shown that inactivation of Apn2 and not Apn1 sens... Ribar, Balazs; Izumi, Tadahide; Mitra, Sankar http://biblioteca.universia.net/ficha.do?id=17940271 A computer program, ARAGORN, identifies tRNA and tmRNA genes. The program employs heuristic algorithms to predict tRNA secondary structure, based on homology with recognized tRNA consensus sequences and ability to form a base-paired cloverleaf. tmRNA genes are identified using a modified version of the BRUCE program. ARAGORN achieves a detection sensitivity of 99% from a set of 1290 eubacterial, eukaryotic and archaeal tRNA genes and detects all complete tmRNA sequences in the tmRNA database,... Laslett, Dean; Canback, Bjorn http://biblioteca.universia.net/ficha.do?id=17940272 Family D DNA polymerase (PolD) is a new type of DNA polymerase possessing polymerization and 3?–5? exonuclease activities. Here we report the characterization of the nuclease activity of PolD from Pyrococcus horikoshii. By site-directed mutagenesis, we verified that the putative Mre11-like nuclease domain in the small subunit (DP1), predicted according to computer analysis and structure inference reported previously, is the catalytic domain. We show that D363, H365 and H454 are the essential ... Shen, Yulong; Tang, Xiao-Feng; Yokoyama, Hideshi; Matsui, Eriko; Matsui, Ikuo http://biblioteca.universia.net/ficha.do?id=17940273 The ?s subunit of Escherichia coli RNA polymerase holoenzyme (E?S) is a key factor of gene expression upon entry into stationary phase and in stressful conditions. The selectivity of promoter recognition by E?S and the housekeeping E?70 is as yet not clearly understood. We used a genetic approach to investigate the interaction of ?S with its target promoters. Starting with down-promoter variants of a ?S promoter target, osmEp, altered in the –10 or –35 elements, we isolated mutant forms of ?S... Checroun, Claire; Bordes, Patricia; Leroy, Olivier; Kolb, Annie; Gutierrez, Claude http://biblioteca.universia.net/ficha.do?id=17940274 PDX1 is a homeodomain transcription factor essential for pancreatic development and mature beta cell function. Homeodomain proteins typically recognize short TAAT DNA motifs in vitro: this binding displays paradoxically low specificity and affinity, given the extremely high specificity of action of these proteins in vivo. To better understand how PDX1 selects target genes in vivo, we have examined the interaction of PDX1 with natural and artificial binding sites. Comparison of PDX1 binding si... Liberzon, Arthur; Ridner, Gabriela; Walker, Michael D. http://biblioteca.universia.net/ficha.do?id=17940275 Site-selective scission of ribonucleic acids (RNAs) has attracted considerable interest, since RNA is an intermediate in gene expression and the genetic material of many pathogenic viruses. Polyamine-imidazole conjugates for site-selective RNA scission, without free imidazole, were synthesized and tested on yeast phenylalanine transfer RNA. These molecules catalyze RNA hydrolysis non-randomly. Within the polyamine chain, the location of the imidazole residue, the numbers of nitrogen atoms and... Fouace, Sandra; Gaudin, Cyril; Picard, Sylvie; Corvaisier, Sophie; Renault, Jacques; Carboni, Bertrand; Felden, Brice http://biblioteca.universia.net/ficha.do?id=17940276 Retroviral particles contain a dimeric RNA genome, which serves as template for the generation of double-stranded DNA by reverse transcription. Transfer between RNA strands during DNA synthesis is governed by both sequence similarity between templates and structural features of the dimeric RNA. A kissing hairpin, believed to facilitate intermolecular recognition and dimer formation, was previously found to be a preferred site for recombination. To investigate if hairpin loop–loop-complementar... Mikkelsen, Jacob Giehm; Rasmussen, Søren Vestergaard; Pedersen, Finn Skou http://biblioteca.universia.net/ficha.do?id=17940277 The DNA methylation status of the protozoan parasite Entamoeba histolytica was heretofore unknown. In the present study, we developed a new technique, based on the affinity of methylated DNA to 5-methylcytosine antibodies, to identify methylated DNA in this parasite. Ribosomal DNA and ribosomal DNA circles were isolated by this method and we confirmed the validity of our approach by sodium bisulfite sequencing. We also report the identification and the characterization of a gene, Ehmeth, enco... Fisher, Ohad; Siman-Tov, Rama; Ankri, Serge http://biblioteca.universia.net/ficha.do?id=17940278 Mutations help us to understand the molecular origins of diseases. Researchers, therefore, both publish and seek disease-relevant mutations in public databases and in scientific literature, e.g. Medline. The retrieval tends to be time-consuming and incomplete. Automated screening of the literature is more efficient. We developed extraction methods (called MEMA) that scan Medline abstracts for mutations. MEMA identified 24?351 singleton mutations in conjunction with a HUGO gene name out of 16?... Rebholz-Schuhmann, Dietrich; Marcel, Stephane; Albert, Sylvie; Tolle, Ralf; Casari, Georg; Kirsch, Harald http://biblioteca.universia.net/ficha.do?id=17940279 The subcomplex of Rpb4 and Rpb7 subunits of RNA pol II in Saccharomyces cerevisiae is known to be an important determinant of transcription under a variety of physiological stresses. In S.cerevisiae, RPB7 is essential for cell viability while rpb4 null strains are temperature sensitive at low and high temperatures. The rpb4 null strain also shows defect in sporulation and a predisposed state of pseudohyphal growth. We show here that, apart from S.cerevisiae Rpb7, the Rpb7 homologs from other ... Singh, Sunanda R.; Rekha, Nambudiry; Pillai, Beena; Singh, Vijender; Naorem, Aruna; Sampath, Vinaya; Srinivasan, N.; Sadhale, Parag P.