81 resultados para chromosome replication


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The bovine RPCI-42 BAC library was screened to construct a sequence-ready ~4 Mb single contig of 92 BAC clones on BTA 1q12. The contig covers the region between the genes KRTAP8P1 and CLIC6. This genomic segment in cattle is of special interest as it contains the dominant gene responsible for the hornless or polled phenotype in cattle. The construction of the BAC contig was initiated by screening the bovine BAC library with heterologous cDNA probes derived from 12 human genes of the syntenic region on HSA 21q22. Contig building was facilitated by BAC end sequencing and chromosome walking. During the construction of the contig, 165 BAC end sequences and 109 single-copy STS markers were generated. For comparative mapping of 25 HSA 21q22 genes, genomic PCR primers were designed from bovine EST sequences and the gene-associated STSs mapped on the contig. Furthermore, bovine BAC end sequence comparisons against the human genome sequence revealed significant matches to HSA 21q22 and allowed the in silico mapping of two new genes in cattle. In total, 31 orthologues of human genes located on HSA 21q22 were directly mapped within the bovine BAC contig, of which 16 genes have been cloned and mapped for the first time in cattle. In contrast to the existing comparative bovine-human RH maps of this region, these results provide a better alignment and reveal a completely conserved gene order in this 4 Mb segment between cattle, human and mouse. The mapping of known polled linked BTA 1q12 microsatellite markers allowed the integration of the physical contig map with existing linkage maps of this region and also determined the exact order of these markers for the first time. Our physical map and transcript map may be useful for positional cloning of the putative polled gene in cattle.

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The mammalian glycinamide ribonucleotide formyltransferase (GART) genes encode a trifunctional polypeptide involved in the de novo purine biosynthesis. We isolated a bacterial artificial chromosome (BAC) clone containing the bovine GART gene and determined the complete DNA sequence of the BAC clone. Cloning and characterization of the bovine GART gene revealed that the bovine gene consists of 23 exons spanning approximately 27 kb. RT-PCR amplification of bovine GART in different organs showed the expression of two GART transcripts in cattle similar to human and mouse. The GART transcripts encode two proteins of 1010 and 433 amino acids, respectively. Eleven single nucleotide polymorphisms (SNPs) were detected in a mutation scan of 24 unrelated animals of three different cattle breeds, including one SNP that affects the amino acid sequence of GART. The chromosomal localization of the gene was determined by fluorescence in situ hybridization. Comparative genome analysis between cattle, human and mouse indicates that the chromosomal location of the bovine GART gene is in agreement with a previously published mapping report.

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Replication-dependent histone genes are up-regulated during the G1/S phase transition to meet the requirement for histones to package the newly synthesized DNA. In mammalian cells, this increment is achieved by enhanced transcription and 3' end processing. The non-polyadenylated histone mRNA 3' ends are generated by a unique mechanism involving the U7 small ribonucleoprotein (U7 snRNP). By using affinity purification methods to enrich U7 snRNA, we identified FUS/TLS as a novel U7 snRNP interacting protein. Both U7 snRNA and histone transcripts can be precipitated by FUS antibodies predominantly in the S phase of the cell cycle. Moreover, FUS depletion leads to decreased levels of correctly processed histone mRNAs and increased levels of extended transcripts. Interestingly, FUS antibodies also co-immunoprecipitate histone transcriptional activator NPAT and transcriptional repressor hnRNP UL1 in different phases of the cell cycle. We further show that FUS binds to histone genes in S phase, promotes the recruitment of RNA polymerase II and is important for the activity of histone gene promoters. Thus, FUS may serve as a linking factor that positively regulates histone gene transcription and 3' end processing by interacting with the U7 snRNP and other factors involved in replication-dependent histone gene expression.

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The hairpin structure at the 3' end of animal histone mRNAs controls histone RNA 3' processing, nucleocytoplasmic transport, translation and stability of histone mRNA. Functionally overlapping, if not identical, proteins binding to the histone RNA hairpin have been identified in nuclear and polysomal extracts. Our own results indicated that these hairpin binding proteins (HBPs) bind their target RNA as monomers and that the resulting ribonucleoprotein complexes are extremely stable. These features prompted us to select for HBP-encoding human cDNAs by RNA-mediated three-hybrid selection in Saccharomyces cerevesiae. Whole cell extract from one selected clone contained a Gal4 fusion protein that interacted with histone hairpin RNA in a sequence- and structure-specific manner similar to a fraction enriched for bovine HBP, indicating that the cDNA encoded HBP. DNA sequence analysis revealed that the coding sequence did not contain any known RNA binding motifs. The HBP gene is composed of eight exons covering 19.5 kb on the short arm of chromosome 4. Translation of the HBP open reading frame in vitro produced a 43 kDa protein with RNA binding specificity identical to murine or bovine HBP. In addition, recombinant HBP expressed in S. cerevisiae was functional in histone pre-mRNA processing, confirming that we have indeed identified the human HBP gene.

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Objective: In schizophrenia, abnormalities in nonverbal behaviors have always been considered as highly relevant. However, due to methodological limitations, nonverbal behavior was rarely quantified objectively. Recent methodological advances now allow a quantification of body movement from ordinary video recordings. We showed that patients’ objectively measured amount of movement in social role-play interactions was closely associated with their symptom profiles (Kupper, Ramseyer, Hoffmann, & Tschacher, Schizophrenia Research 2010). In the present study, a replication of these results in the context of semi-standardized PANSS (Positive and Negative Syndrome Scale) interviews was intended. Methods: 17 patients with schizophrenia were analyzed during the initial 15-min sequence of a videotaped PANSS interview using Motion Energy Analysis (MEA). The amount of patients’ movement was then correlated with their PANSS symptom scores. Results: Sizeable and significant correlations between negative symptoms and reduced movements (r = -.68, p<0.01) and reduced movement speed (r = -.80, p<0.001) were found. Moreover, cognitive symptoms were related to reduced movement speed (r = -.70, p<.01). Conclusion: Negative symptoms were reliably indicated by patients’ nonverbal behavior in psychopathology interviews. Hence, the main result of our earlier study, examining patients’ nonverbal behavior in role play tests, was replicated for the less structured interactions in psychopathological interviews. Results could encourage the use of MEA in a wide range of videotaped social interactions of patients with schizophrenia and other psychiatric disorders.

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Ultrastructural analysis of the polydnavirus of the braconid wasp Chelonus inanitus revealed that virions consist of one cylindrical nucleocapsid enveloped by a single unit membrane. Nucleocapsids have a constant diameter of 33.7 +/- 1.4 nm and a variable length of between 8 and 46 nm. Spreading of viral DNA showed that the genome consists of circular dsDNA molecules of variable sizes and measurement of the contour lengths indicated sizes of between 7 and 31 kbp. When virions were exposed to osmotic shock conditions to release the DNA, only one circular molecule was released per particle suggesting that the various DNA molecules are singly encapsidated in this bracovirus. The viral genome was seen to consist of at least 10 different segments and the aggregate genome size is in the order of 200 kbp. By partial digestion of viral DNA with HindIII or EcoRI in the presence of ethidium bromide and subsequent ligation with HindIII-cut pSP65 or EcoRI-cut pSP64 and transfection into Escherichia coli, libraries of 103 HindIII and 23 EcoRI clones were obtained. Southern blots revealed that complete and unrearranged segments were cloned with this approach, and restriction maps for five segments were obtained. Part of a 16.8 kbp segment was sequenced, found to be AT-rich (73%) and to contain six copies of a 17 bp repeated sequence. The development of the female reproductive tract in the course of pupal-adult development of the wasp was investigated and seen to be strictly correlated with the pigmentation pattern. By the use of a semiquantitative PCR, replication of viral DNA was observed to initiate at a specific stage of pupal-adult development.

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This paper investigates the role of artefacts for the replication or routines in organizations. Drawing on data of a large franchise organization in the UK, we show that actors' engagement with a portfolio of different primary (e.g. software, tools) and secondary (e.g. manuals) artefacts that are part of the business format, gives rise to five artefact enabled practices of replication (activity scoping, time patterning, practical enquiry, use in practice and contextual enquiry). Importantly, these practices of replication enable three different types of franchisee agency (iterational, practical evaluative and projective agency) that support but partly also challenge replication in terms of the similarity of organizational routines across units. Our findings have several theoretical contributions for the growing literature on replication as well as materiality and artefacts in organizations.

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Classical swine fever virus (CSFV) causes a highly contagious disease in pigs that can range from a severe haemorrhagic fever to a nearly unapparent disease, depending on the virulence of the virus strain. Little is known about the viral molecular determinants of CSFV virulence. The nonstructural protein NS4B is essential for viral replication. However, the roles of CSFV NS4B in viral genome replication and pathogenesis have not yet been elucidated. NS4B of the GPE-  vaccine strain and of the highly virulent Eystrup strain differ by a total of seven amino acid residues, two of which are located in the predicted trans-membrane domains of NS4B and were described previously to relate to virulence, and five residues clustering in the N-terminal part. In the present study, we examined the potential role of these five amino acids in modulating genome replication and determining pathogenicity in pigs. A chimeric low virulent GPE- -derived virus carrying the complete Eystrup NS4B showed enhanced pathogenicity in pigs. The in vitro replication efficiency of the NS4B chimeric GPE-  replicon was significantly higher than that of the replicon carrying only the two Eystrup-specific amino acids in NS4B. In silico and in vitro data suggest that the N-terminal part of NS4B forms an amphipathic α-helix structure. The N-terminal NS4B with these five amino acid residues is associated with the intracellular membranes. Taken together, this is the first gain-of-function study showing that the N-terminal domain of NS4B can determine CSFV genome replication in cell culture and viral pathogenicity in pigs.

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The replication of coronaviruses, as in other positive-strand RNA viruses, is closely tied to the formation of membrane-bound replicative organelles inside infected cells. The proteins responsible for rearranging cellular membranes to form the organelles are conserved not just among the Coronaviridae family members, but across the order Nidovirales. Taken together, these observations suggest that the coronavirus replicative organelle plays an important role in viral replication, perhaps facilitating the production or protection of viral RNA. However, the exact nature of this role, and the specific contexts under which it is important have not been fully elucidated. Here, we collect and interpret the recent experimental evidence about the role and importance of membrane-bound organelles in coronavirus replication.

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The U7 snRNA, together with both common and unique snRNP proteins, forms the U7 snRNP particle. This particle is a major component of the 3' processing machinery that converts histone pre-mRNA into mature mRNA in the eukaryotic nucleus. The genes for many snRNAs are present in multiple copies and often have many pseudogenes. Southern blot experiments using U7 oligonucleotide and gene probes have identified only one strongly hybridizing band and three weakly hybridizing bands in mouse genomic DNA. Previously, two laboratories isolated genomic clones encoding one functional U7 gene and three presumed pseudogenes. Since all the genes were isolated on separate, nonoverlapping genomic fragments, the four genes are not tightly clustered in the mouse genome. In this study, we use fluorescence in situ hybridization to determine the chromosomal locations of these clones and their possible linkage to histone loci. Two of the pseudogenes map to mouse Chromosome 1, but are many megabases apart, whereas the active U7 gene maps to Chromosome 6. Possible mechanisms for this localization pattern are discussed.

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A novel staphylococcal cassette chromosome mec (SCCmec) composite island (SCCmecAI16-SCCczrAI16-CI) was identified in Staphylococcus pseudintermedius. Four integration site sequences for SCC subdivided the 60,734-bp island into 41,232-bp SCCmecAI16, 19,400-bp SCCczrAI16, and 102-bp SCC-likeAI16 elements. SCCmecAI16 represents a new combination of ccrA1B3 genes with a class A mec complex. SCCczrAI16 contains ccrA1B6 and genes related to restriction modification and heavy metal resistance. SCCmecAI16-SCCczrAI16-CI was found in methicillin-resistant S. pseudintermedius sequence type 112 (ST112) and ST111 isolated from dogs and veterinarians in Thailand.

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A methicillin-resistant mecB-positive Macrococcus caseolyticus (strain KM45013) was isolated from the nares of a dog with rhinitis. It contained a novel 39-kb transposon-defective complete mecB-carrying staphylococcal cassette chromosome mec element (SCCmecKM45013). SCCmecKM45013 contained 49 coding sequences (CDSs), was integrated at the 3' end of the chromosomal orfX gene, and was delimited at both ends by imperfect direct repeats functioning as integration site sequences (ISSs). SCCmecKM45013 presented two discontinuous regions of homology (SCCmec coverage of 35%) to the chromosomal and transposon Tn6045-associated SCCmec-like element of M. caseolyticus JCSC7096: (i) the mec gene complex (98.8% identity) and (ii) the ccr-carrying segment (91.8% identity). The mec gene complex, located at the right junction of the cassette, also carried the β-lactamase gene blaZm (mecRm-mecIm-mecB-blaZm). SCCmecKM45013 contained two cassette chromosome recombinase genes, ccrAm2 and ccrBm2, which shared 94.3% and 96.6% DNA identity with those of the SCCmec-like element of JCSC7096 but shared less than 52% DNA identity with the staphylococcal ccrAB and ccrC genes. Three distinct extrachromosomal circularized elements (the entire SCCmecKM45013, ΨSCCmecKM45013 lacking the ccr genes, and SCCKM45013 lacking mecB) flanked by one ISS copy, as well as the chromosomal regions remaining after excision, were detected. An unconventional circularized structure carrying the mecB gene complex was associated with two extensive direct repeat regions, which enclosed two open reading frames (ORFs) (ORF46 and ORF51) flanking the chromosomal mecB-carrying gene complex. This study revealed M. caseolyticus as a potential disease-associated bacterium in dogs and also unveiled an SCCmec element carrying mecB not associated with Tn6045 in the genus Macrococcus.