sequencing newly replicated: Topics by Science.gov

Sample records for sequencing newly replicated

Genome-wide identification and characterisation of human DNA replication origins by initiation site sequencing (ini-seq)

PubMed Central

Langley, Alexander R.; Gräf, Stefan; Smith, James C.; Krude, Torsten

2016-01-01

Next-generation sequencing has enabled the genome-wide identification of human DNA replication origins. However, different approaches to mapping replication origins, namely (i) sequencing isolated small nascent DNA strands (SNS-seq); (ii) sequencing replication bubbles (bubble-seq) and (iii) sequencing Okazaki fragments (OK-seq), show only limited concordance. To address this controversy, we describe here an independent high-resolution origin mapping technique that we call initiation site sequencing (ini-seq). In this approach, newly replicated DNA is directly labelled with digoxigenin-dUTP near the sites of its initiation in a cell-free system. The labelled DNA is then immunoprecipitated and genomic locations are determined by DNA sequencing. Using this technique we identify >25,000 discrete origin sites at sub-kilobase resolution on the human genome, with high concordance between biological replicates. Most activated origins identified by ini-seq are found at transcriptional start sites and contain G-quadruplex (G4) motifs. They tend to cluster in early-replicating domains, providing a correlation between early replication timing and local density of activated origins. Origins identified by ini-seq show highest concordance with sites identified by SNS-seq, followed by OK-seq and bubble-seq. Furthermore, germline origins identified by positive nucleotide distribution skew jumps overlap with origins identified by ini-seq and OK-seq more frequently and more specifically than do sites identified by either SNS-seq or bubble-seq. PMID:27587586
Genome-wide identification and characterisation of human DNA replication origins by initiation site sequencing (ini-seq).

PubMed

Langley, Alexander R; Gräf, Stefan; Smith, James C; Krude, Torsten

2016-12-01

Next-generation sequencing has enabled the genome-wide identification of human DNA replication origins. However, different approaches to mapping replication origins, namely (i) sequencing isolated small nascent DNA strands (SNS-seq); (ii) sequencing replication bubbles (bubble-seq) and (iii) sequencing Okazaki fragments (OK-seq), show only limited concordance. To address this controversy, we describe here an independent high-resolution origin mapping technique that we call initiation site sequencing (ini-seq). In this approach, newly replicated DNA is directly labelled with digoxigenin-dUTP near the sites of its initiation in a cell-free system. The labelled DNA is then immunoprecipitated and genomic locations are determined by DNA sequencing. Using this technique we identify >25,000 discrete origin sites at sub-kilobase resolution on the human genome, with high concordance between biological replicates. Most activated origins identified by ini-seq are found at transcriptional start sites and contain G-quadruplex (G4) motifs. They tend to cluster in early-replicating domains, providing a correlation between early replication timing and local density of activated origins. Origins identified by ini-seq show highest concordance with sites identified by SNS-seq, followed by OK-seq and bubble-seq. Furthermore, germline origins identified by positive nucleotide distribution skew jumps overlap with origins identified by ini-seq and OK-seq more frequently and more specifically than do sites identified by either SNS-seq or bubble-seq. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.
Conserved Sequences at the Origin of Adenovirus DNA Replication

PubMed Central

Stillman, Bruce W.; Topp, William C.; Engler, Jeffrey A.

1982-01-01

The origin of adenovirus DNA replication lies within an inverted sequence repetition at either end of the linear, double-stranded viral DNA. Initiation of DNA replication is primed by a deoxynucleoside that is covalently linked to a protein, which remains bound to the newly synthesized DNA. We demonstrate that virion-derived DNA-protein complexes from five human adenovirus serological subgroups (A to E) can act as a template for both the initiation and the elongation of DNA replication in vitro, using nuclear extracts from adenovirus type 2 (Ad2)-infected HeLa cells. The heterologous template DNA-protein complexes were not as active as the homologous Ad2 DNA, most probably due to inefficient initiation by Ad2 replication factors. In an attempt to identify common features which may permit this replication, we have also sequenced the inverted terminal repeated DNA from human adenovirus serotypes Ad4 (group E), Ad9 and Ad10 (group D), and Ad31 (group A), and we have compared these to previously determined sequences from Ad2 and Ad5 (group C), Ad7 (group B), and Ad12 and Ad18 (group A) DNA. In all cases, the sequence around the origin of DNA replication can be divided into two structural domains: a proximal A · T-rich region which is partially conserved among these serotypes, and a distal G · C-rich region which is less well conserved. The G · C-rich region contains sequences similar to sequences present in papovavirus replication origins. The two domains may reflect a dual mechanism for initiation of DNA replication: adenovirus-specific protein priming of replication, and subsequent utilization of this primer by host replication factors for completion of DNA synthesis. Images PMID:7143575
Evaluation of the reproducibility of amplicon sequencing with Illumina MiSeq platform

PubMed Central

Van Nostrand, Joy D.; Ning, Daliang; Sun, Bo; Xue, Kai; Liu, Feifei; Deng, Ye; Liang, Yuting; Zhou, Jizhong

2017-01-01

Illumina’s MiSeq has become the dominant platform for gene amplicon sequencing in microbial ecology studies; however, various technical concerns, such as reproducibility, still exist. To assess reproducibility, 16S rRNA gene amplicons from 18 soil samples of a reciprocal transplantation experiment were sequenced on an Illumina MiSeq. The V4 region of 16S rRNA gene from each sample was sequenced in triplicate with each replicate having a unique barcode. The average OTU overlap, without considering sequence abundance, at a rarefaction level of 10,323 sequences was 33.4±2.1% and 20.2±1.7% between two and among three technical replicates, respectively. When OTU sequence abundance was considered, the average sequence abundance weighted OTU overlap was 85.6±1.6% and 81.2±2.1% for two and three replicates, respectively. Removing singletons significantly increased the overlap for both (~1–3%, p<0.001). Increasing the sequencing depth to 160,000 reads by deep sequencing increased OTU overlap both when sequence abundance was considered (95%) and when not (44%). However, if singletons were not removed the overlap between two technical replicates (not considering sequence abundance) plateaus at 39% with 30,000 sequences. Diversity measures were not affected by the low overlap as α-diversities were similar among technical replicates while β-diversities (Bray-Curtis) were much smaller among technical replicates than among treatment replicates (e.g., 0.269 vs. 0.374). Higher diversity coverage, but lower OTU overlap, was observed when replicates were sequenced in separate runs. Detrended correspondence analysis indicated that while there was considerable variation among technical replicates, the reproducibility was sufficient for detecting treatment effects for the samples examined. These results suggest that although there is variation among technical replicates, amplicon sequencing on MiSeq is useful for analyzing microbial community structure if used appropriately and with caution. For example, including technical replicates, removing spurious sequences and unrepresentative OTUs, using a clustering method with a high stringency for OTU generation, estimating treatment effects at higher taxonomic levels, and adapting the unique molecular identifier (UMI) and other newly developed methods to lower PCR and sequencing error and to identify true low abundance rare species all can increase reproducibility. PMID:28453559
Evaluation of the reproducibility of amplicon sequencing with Illumina MiSeq platform

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wen, Chongqing; Wu, Liyou; Qin, Yujia

Illumina's MiSeq has become the dominant platform for gene amplicon sequencing in microbial ecology studies; however, various technical concerns, such as reproducibility, still exist. To assess reproducibility, 16S rRNA gene amplicons from 18 soil samples of a reciprocal transplantation experiment were sequenced on an Illumina MiSeq. The V4 region of 16S rRNA gene from each sample was sequenced in triplicate with each replicate having a unique barcode. The average OTU overlap, without considering sequence abundance, at a rarefaction level of 10,323 sequences was 33.4±2.1% and 20.2±1.7% between two and among three technical replicates, respectively. When OTU sequence abundance was considered,more » the average sequence abundance weighted OTU overlap was 85.6±1.6% and 81.2±2.1% for two and three replicates, respectively. Removing singletons significantly increased the overlap for both (~1-3%, p<0.001). Increasing the sequencing depth to 160,000 reads by deep sequencing increased OTU overlap both when sequence abundance was considered (95%) and when not (44%). However, if singletons were not removed the overlap between two technical replicates (not considering sequence abundance) plateaus at 39% with 30,000 sequences. Diversity measures were not affected by the low overlap as α-diversities were similar among technical replicates while β-diversities (Bray-Curtis) were much smaller among technical replicates than among treatment replicates (e.g., 0.269 vs. 0.374). Higher diversity coverage, but lower OTU overlap, was observed when replicates were sequenced in separate runs. Detrended correspondence analysis indicated that while there was considerable variation among technical replicates, the reproducibility was sufficient for detecting treatment effects for the samples examined. These results suggest that although there is variation among technical replicates, amplicon sequencing on MiSeq is useful for analyzing microbial community structure if used appropriately and with caution. For example, including technical replicates, removing spurious sequences and unrepresentative OTUs, using a clustering method with a high stringency for OTU generation, estimating treatment effects at higher taxonomic levels, and adapting the unique molecular identifier (UMI) and other newly developed methods to lower PCR and sequencing error and to identify true low abundance rare species all can increase reproducibility.« less
Evaluation of the reproducibility of amplicon sequencing with Illumina MiSeq platform

DOE PAGES

Wen, Chongqing; Wu, Liyou; Qin, Yujia; ...

2017-04-28

Illumina's MiSeq has become the dominant platform for gene amplicon sequencing in microbial ecology studies; however, various technical concerns, such as reproducibility, still exist. To assess reproducibility, 16S rRNA gene amplicons from 18 soil samples of a reciprocal transplantation experiment were sequenced on an Illumina MiSeq. The V4 region of 16S rRNA gene from each sample was sequenced in triplicate with each replicate having a unique barcode. The average OTU overlap, without considering sequence abundance, at a rarefaction level of 10,323 sequences was 33.4±2.1% and 20.2±1.7% between two and among three technical replicates, respectively. When OTU sequence abundance was considered,more » the average sequence abundance weighted OTU overlap was 85.6±1.6% and 81.2±2.1% for two and three replicates, respectively. Removing singletons significantly increased the overlap for both (~1-3%, p<0.001). Increasing the sequencing depth to 160,000 reads by deep sequencing increased OTU overlap both when sequence abundance was considered (95%) and when not (44%). However, if singletons were not removed the overlap between two technical replicates (not considering sequence abundance) plateaus at 39% with 30,000 sequences. Diversity measures were not affected by the low overlap as α-diversities were similar among technical replicates while β-diversities (Bray-Curtis) were much smaller among technical replicates than among treatment replicates (e.g., 0.269 vs. 0.374). Higher diversity coverage, but lower OTU overlap, was observed when replicates were sequenced in separate runs. Detrended correspondence analysis indicated that while there was considerable variation among technical replicates, the reproducibility was sufficient for detecting treatment effects for the samples examined. These results suggest that although there is variation among technical replicates, amplicon sequencing on MiSeq is useful for analyzing microbial community structure if used appropriately and with caution. For example, including technical replicates, removing spurious sequences and unrepresentative OTUs, using a clustering method with a high stringency for OTU generation, estimating treatment effects at higher taxonomic levels, and adapting the unique molecular identifier (UMI) and other newly developed methods to lower PCR and sequencing error and to identify true low abundance rare species all can increase reproducibility.« less
Evaluation of the reproducibility of amplicon sequencing with Illumina MiSeq platform.

PubMed

Wen, Chongqing; Wu, Liyou; Qin, Yujia; Van Nostrand, Joy D; Ning, Daliang; Sun, Bo; Xue, Kai; Liu, Feifei; Deng, Ye; Liang, Yuting; Zhou, Jizhong

2017-01-01

Illumina's MiSeq has become the dominant platform for gene amplicon sequencing in microbial ecology studies; however, various technical concerns, such as reproducibility, still exist. To assess reproducibility, 16S rRNA gene amplicons from 18 soil samples of a reciprocal transplantation experiment were sequenced on an Illumina MiSeq. The V4 region of 16S rRNA gene from each sample was sequenced in triplicate with each replicate having a unique barcode. The average OTU overlap, without considering sequence abundance, at a rarefaction level of 10,323 sequences was 33.4±2.1% and 20.2±1.7% between two and among three technical replicates, respectively. When OTU sequence abundance was considered, the average sequence abundance weighted OTU overlap was 85.6±1.6% and 81.2±2.1% for two and three replicates, respectively. Removing singletons significantly increased the overlap for both (~1-3%, p<0.001). Increasing the sequencing depth to 160,000 reads by deep sequencing increased OTU overlap both when sequence abundance was considered (95%) and when not (44%). However, if singletons were not removed the overlap between two technical replicates (not considering sequence abundance) plateaus at 39% with 30,000 sequences. Diversity measures were not affected by the low overlap as α-diversities were similar among technical replicates while β-diversities (Bray-Curtis) were much smaller among technical replicates than among treatment replicates (e.g., 0.269 vs. 0.374). Higher diversity coverage, but lower OTU overlap, was observed when replicates were sequenced in separate runs. Detrended correspondence analysis indicated that while there was considerable variation among technical replicates, the reproducibility was sufficient for detecting treatment effects for the samples examined. These results suggest that although there is variation among technical replicates, amplicon sequencing on MiSeq is useful for analyzing microbial community structure if used appropriately and with caution. For example, including technical replicates, removing spurious sequences and unrepresentative OTUs, using a clustering method with a high stringency for OTU generation, estimating treatment effects at higher taxonomic levels, and adapting the unique molecular identifier (UMI) and other newly developed methods to lower PCR and sequencing error and to identify true low abundance rare species all can increase reproducibility.
Epigenetic Instability due to Defective Replication of Structured DNA

PubMed Central

Sarkies, Peter; Reams, Charlie; Simpson, Laura J.; Sale, Julian E.

2010-01-01

Summary The accurate propagation of histone marks during chromosomal replication is proposed to rely on the tight coupling of replication with the recycling of parental histones to the daughter strands. Here, we show in the avian cell line DT40 that REV1, a key regulator of DNA translesion synthesis at the replication fork, is required for the maintenance of repressive chromatin marks and gene silencing in the vicinity of DNA capable of forming G-quadruplex (G4) structures. We demonstrate a previously unappreciated requirement for REV1 in replication of G4 forming sequences and show that transplanting a G4 forming sequence into a silent locus leads to its derepression in REV1-deficient cells. Together, our observations support a model in which failure to maintain processive DNA replication at G4 DNA in REV1-deficient cells leads to uncoupling of DNA synthesis from histone recycling, resulting in localized loss of repressive chromatin through biased incorporation of newly synthesized histones. PMID:21145480
Assessment of the cPAS-based BGISEQ-500 platform for metagenomic sequencing.

PubMed

Fang, Chao; Zhong, Huanzi; Lin, Yuxiang; Chen, Bing; Han, Mo; Ren, Huahui; Lu, Haorong; Luber, Jacob M; Xia, Min; Li, Wangsheng; Stein, Shayna; Xu, Xun; Zhang, Wenwei; Drmanac, Radoje; Wang, Jian; Yang, Huanming; Hammarström, Lennart; Kostic, Aleksandar D; Kristiansen, Karsten; Li, Junhua

2018-03-01

More extensive use of metagenomic shotgun sequencing in microbiome research relies on the development of high-throughput, cost-effective sequencing. Here we present a comprehensive evaluation of the performance of the new high-throughput sequencing platform BGISEQ-500 for metagenomic shotgun sequencing and compare its performance with that of 2 Illumina platforms. Using fecal samples from 20 healthy individuals, we evaluated the intra-platform reproducibility for metagenomic sequencing on the BGISEQ-500 platform in a setup comprising 8 library replicates and 8 sequencing replicates. Cross-platform consistency was evaluated by comparing 20 pairwise replicates on the BGISEQ-500 platform vs the Illumina HiSeq 2000 platform and the Illumina HiSeq 4000 platform. In addition, we compared the performance of the 2 Illumina platforms against each other. By a newly developed overall accuracy quality control method, an average of 82.45 million high-quality reads (96.06% of raw reads) per sample, with 90.56% of bases scoring Q30 and above, was obtained using the BGISEQ-500 platform. Quantitative analyses revealed extremely high reproducibility between BGISEQ-500 intra-platform replicates. Cross-platform replicates differed slightly more than intra-platform replicates, yet a high consistency was observed. Only a low percentage (2.02%-3.25%) of genes exhibited significant differences in relative abundance comparing the BGISEQ-500 and HiSeq platforms, with a bias toward genes with higher GC content being enriched on the HiSeq platforms. Our study provides the first set of performance metrics for human gut metagenomic sequencing data using BGISEQ-500. The high accuracy and technical reproducibility confirm the applicability of the new platform for metagenomic studies, though caution is still warranted when combining metagenomic data from different platforms.
High-frequency transformation of a methylotrophic yeast, Candida boidinii, with autonomously replicating plasmids which are also functional in Saccharomyces cerevisiae.

PubMed

Sakai, Y; Goh, T K; Tani, Y

1993-06-01

We have developed a transformation system which uses autonomous replicating plasmids for a methylotrophic yeast, Candida boidinii. Two autonomous replication sequences, CARS1 and CARS2, were newly cloned from the genome of C. boidinii. Plasmids having both a CARS fragment and the C. boidinii URA3 gene transformed C. boidinii ura3 cells to Ura+ phenotype at frequencies of up to 10(4) CFU/micrograms of DNA. From Southern blot analysis, CARS plasmids seemed to exist in polymeric forms as well as in monomeric forms in C. boidinii cells. The C. boidinii URA3 gene was overexpressed in C. boidinii on these CARS vectors. CARS1 and CARS2 were found to function as an autonomous replicating element in Saccharomyces cerevisiae as well. Different portions of the CARS1 sequence were needed for autonomous replicating activity in C. boidinii and S. cerevisiae. C. boidinii could also be transformed with vectors harboring a CARS fragment and the S. cerevisiae URA3 gene.
DNA synthesis by Pol η promotes fragile site stability by preventing under-replicated DNA in mitosis

PubMed Central

Bergoglio, Valérie; Boyer, Anne-Sophie; Walsh, Erin; Naim, Valeria; Legube, Gaëlle; Lee, Marietta Y.W.T.; Rey, Laurie; Rosselli, Filippo; Cazaux, Christophe; Eckert, Kristin A.

2013-01-01

Human DNA polymerase η (Pol η) is best known for its role in responding to UV irradiation–induced genome damage. We have recently observed that Pol η is also required for the stability of common fragile sites (CFSs), whose rearrangements are considered a driving force of oncogenesis. Here, we explored the molecular mechanisms underlying this newly identified role. We demonstrated that Pol η accumulated at CFSs upon partial replication stress and could efficiently replicate non-B DNA sequences within CFSs. Pol η deficiency led to persistence of checkpoint-blind under-replicated CFS regions in mitosis, detectable as FANCD2-associated chromosomal sites that were transmitted to daughter cells in 53BP1-shielded nuclear bodies. Expression of a catalytically inactive mutant of Pol η increased replication fork stalling and activated the replication checkpoint. These data are consistent with the requirement of Pol η–dependent DNA synthesis during S phase at replication forks stalled in CFS regions to suppress CFS instability by preventing checkpoint-blind under-replicated DNA in mitosis. PMID:23609533
Molecular Weight of Deoxyribonucleic Acid Synthesized During Initiation of Chromosome Replication in Escherichia coli

PubMed Central

Kuempel, Peter L.

1972-01-01

Alkaline sucrose gradients were used to study the molecular weight of deoxyribonucleic acid (DNA) synthesized during the initiation of chromosome replication in Escherichia coli 15 TAU-bar. The experiments were conducted to determine whether newly synthesized, replication origin DNA is attached to higher-molecular-weight parental DNA. Little of the DNA synthesized after readdition of required amino acids to cells previously deprived of the amino acids was present in DNA with a molecular weight comparable to that of the parental DNA. The newly synthesized, low-molecular-weight DNA rapidly appeared in higher-molecular-weight material, but there was an upper limit to the size of this intermediate-molecular-weight DNA. This limit was not observed when exponentially growing cells converted newly synthesized DNA to higher-molecular-weight material. The size of the intermediate-molecular-weight DNA was related to the age of the replication forks, and the size increased as the replication forks moved further from the replication origin. The results indicate that the newly synthesized replication origin DNA is not attached to parental DNA, but it is rapidly attached to the growing strands that extend from the replication fork to the replication origin, or to the other replication fork if replication is bidirectional. Experiments are reported which demonstrate that the DNA investigated was from the vicinity of the replication origin and was not plasmid DNA or DNA from random positions on the chromosome. PMID:4562387
Molecular Evolution and Functional Diversification of Replication Protein A1 in Plants

PubMed Central

Aklilu, Behailu B.; Culligan, Kevin M.

2016-01-01

Replication protein A (RPA) is a heterotrimeric, single-stranded DNA binding complex required for eukaryotic DNA replication, repair, and recombination. RPA is composed of three subunits, RPA1, RPA2, and RPA3. In contrast to single RPA subunit genes generally found in animals and yeast, plants encode multiple paralogs of RPA subunits, suggesting subfunctionalization. Genetic analysis demonstrates that five Arabidopsis thaliana RPA1 paralogs (RPA1A to RPA1E) have unique and overlapping functions in DNA replication, repair, and meiosis. We hypothesize here that RPA1 subfunctionalities will be reflected in major structural and sequence differences among the paralogs. To address this, we analyzed amino acid and nucleotide sequences of RPA1 paralogs from 25 complete genomes representing a wide spectrum of plants and unicellular green algae. We find here that the plant RPA1 gene family is divided into three general groups termed RPA1A, RPA1B, and RPA1C, which likely arose from two progenitor groups in unicellular green algae. In the family Brassicaceae the RPA1B and RPA1C groups have further expanded to include two unique sub-functional paralogs RPA1D and RPA1E, respectively. In addition, RPA1 groups have unique domains, motifs, cis-elements, gene expression profiles, and pattern of conservation that are consistent with proposed functions in monocot and dicot species, including a novel C-terminal zinc-finger domain found only in plant RPA1C-like sequences. These results allow for improved prediction of RPA1 subunit functions in newly sequenced plant genomes, and potentially provide a unique molecular tool to improve classification of Brassicaceae species. PMID:26858742
Kinetics and thermodynamics of exonuclease-deficient DNA polymerases

NASA Astrophysics Data System (ADS)

Gaspard, Pierre

2016-04-01

A kinetic theory is developed for exonuclease-deficient DNA polymerases, based on the experimental observation that the rates depend not only on the newly incorporated nucleotide, but also on the previous one, leading to the growth of Markovian DNA sequences from a Bernoullian template. The dependencies on nucleotide concentrations and template sequence are explicitly taken into account. In this framework, the kinetic and thermodynamic properties of DNA replication, in particular, the mean growth velocity, the error probability, and the entropy production are calculated analytically in terms of the rate constants and the concentrations. Theory is compared with numerical simulations for the DNA polymerases of T7 viruses and human mitochondria.
Comparison of biological and genomic characteristics between a newly isolated mink enteritis parvovirus MEV-LHV and an attenuated strain MEV-L.

PubMed

Mao, Yaping; Wang, Jigui; Hou, Qiang; Xi, Ji; Zhang, Xiaomei; Bian, Dawei; Yu, Yongle; Wang, Xi; Liu, Weiquan

2016-06-01

A virus isolated from mink showing clinical signs of enteritis was identified as a high virulent mink enteritis parvovirus (MEV) based on its biological characteristics in vivo and in vitro. Mink, challenged with this strain named MEV-LHV, exhibited severe pathological lesions as compared to those challenged with attenuated strain MEV-L. MEV-LHV also showed higher infection and replication efficiencies in vitro than MEV-L. Sequence of the complete genome of MEV-LHV was determined and analyzed in comparison with those in GenBank, which revealed that MEV-LHV shared high homology with virulent strain MEV SD12/01, whereas MEV-L was closely related to Abashiri and vaccine strain MEVB, and belonged to a different branch of the phylogenetic tree. The genomes of the two strains differed by insertions and deletions in their palindromic termini and specific unique mutations (especially VP2 300) in coding sequences which may be involved in viral replication and pathogenicity. The results of this study provide a better understanding of the biological and genomic characteristics of MEV and identify certain regions and sites that may be involved in viral replication and pathogenicity.
ATAD2 is an epigenetic reader of newly synthesized histone marks during DNA replication.

PubMed

Koo, Seong Joo; Fernández-Montalván, Amaury E; Badock, Volker; Ott, Christopher J; Holton, Simon J; von Ahsen, Oliver; Toedling, Joern; Vittori, Sarah; Bradner, James E; Gorjánácz, Mátyás

2016-10-25

ATAD2 (ATPase family AAA domain-containing protein 2) is a chromatin regulator harboring an AAA+ ATPase domain and a bromodomain, previously proposed to function as an oncogenic transcription co-factor. Here we suggest that ATAD2 is also required for DNA replication. ATAD2 is co-expressed with genes involved in DNA replication in various cancer types and predominantly expressed in S phase cells where it localized on nascent chromatin (replication sites). Our extensive biochemical and cellular analyses revealed that ATAD2 is recruited to replication sites through a direct interaction with di-acetylated histone H4 at K5 and K12, indicative of newly synthesized histones during replication-coupled chromatin reassembly. Similar to ATAD2-depletion, ectopic expression of ATAD2 mutants that are deficient in binding to these di-acetylation marks resulted in reduced DNA replication and impaired loading of PCNA onto chromatin, suggesting relevance of ATAD2 in DNA replication. Taken together, our data show a novel function of ATAD2 in cancer and for the first time identify a reader of newly synthesized histone di-acetylation-marks during replication.
Electronic hybridization detection in microarray format and DNA genotyping

NASA Astrophysics Data System (ADS)

Blin, Antoine; Cissé, Ismaïl; Bockelmann, Ulrich

2014-02-01

We describe an approach to substituting a fluorescence microarray with a surface made of an arrangement of electrolyte-gated field effect transistors. This was achieved using a dedicated blocking of non-specific interactions and comparing threshold voltage shifts of transistors exhibiting probe molecules of different base sequence. We apply the approach to detection of the 35delG mutation, which is related to non-syndromic deafness and is one of the most frequent mutations in humans. The process involves barcode sequences that are generated by Tas-PCR, a newly developed replication reaction using polymerase blocking. The barcodes are recognized by hybridization to surface attached probes and are directly detected by the semiconductor device.
Electronic hybridization detection in microarray format and DNA genotyping

PubMed Central

Blin, Antoine; Cissé, Ismaïl; Bockelmann, Ulrich

2014-01-01

We describe an approach to substituting a fluorescence microarray with a surface made of an arrangement of electrolyte-gated field effect transistors. This was achieved using a dedicated blocking of non-specific interactions and comparing threshold voltage shifts of transistors exhibiting probe molecules of different base sequence. We apply the approach to detection of the 35delG mutation, which is related to non-syndromic deafness and is one of the most frequent mutations in humans. The process involves barcode sequences that are generated by Tas-PCR, a newly developed replication reaction using polymerase blocking. The barcodes are recognized by hybridization to surface attached probes and are directly detected by the semiconductor device. PMID:24569823
Targets of small interfering RNA restriction during human immunodeficiency virus type 1 replication.

PubMed

Gao, Yong; Lobritz, Michael A; Roth, Justin; Abreha, Measho; Nelson, Kenneth N; Nankya, Immaculate; Moore-Dudley, Dawn M; Abraha, Awet; Gerson, Stanton L; Arts, Eric J

2008-03-01

Small interfering RNAs (siRNAs) have been shown to effectively inhibit human immunodeficiency virus type 1 (HIV-1) replication in vitro. The mechanism(s) for this inhibition is poorly understood, as siRNAs may interact with multiple HIV-1 RNA species during different steps of the retroviral life cycle. To define susceptible HIV-1 RNA species, siRNAs were first designed to specifically inhibit two divergent primary HIV-1 isolates via env and gag gene targets. A self-inactivating lentiviral vector harboring these target sequences confirmed that siRNA cannot degrade incoming genomic RNA. Disruption of the incoming core structure by rhesus macaque TRIM5alpha did, however, provide siRNA-RNA-induced silencing complex access to HIV-1 genomic RNA and promoted degradation. In the absence of accelerated core disruption, only newly transcribed HIV-1 mRNA in the cytoplasm is sensitive to siRNA degradation. Inhibitors of HIV-1 mRNA nuclear export, such as leptomycin B and camptothecin, blocked siRNA restriction. All HIV-1 RNA regions and transcripts found 5' of the target sequence, including multiply spliced HIV-1 RNA, were degraded by unidirectional 3'-to-5' siRNA amplification and spreading. In contrast, HIV-1 RNA 3' of the target sequence was not susceptible to siRNA. Even in the presence of siRNA, full-length HIV-1 RNA is still encapsidated into newly assembled viruses. These findings suggest that siRNA can target only a relatively "naked" cytoplasmic HIV-1 RNA despite the involvement of viral RNA at nearly every step in the retroviral life cycle. Protection of HIV-1 RNA within the core following virus entry, during encapsidation/virus assembly, or within the nucleus may reflect virus evolution in response to siRNA, TRIM5alpha, or other host restriction factors.
Slow Joining of Newly Replicated DNA Chains in DNA Polymerase I-Deficient Escherichia coli Mutants*

PubMed Central

Okazaki, Reiji; Arisawa, Mikio; Sugino, Akio

1971-01-01

In Escherichia coli mutants deficient in DNA polymerase I, newly replicated short DNA is joined at about 10% of the rate in the wild-type strains. It is postulated that DNA polymerase I normally functions in filling gaps between the nascent short segments synthesized by the replication complex. Possible implications of the finding are discussed in relation to other abnormal properties of these mutants. PMID:4943548

Replication-coupled chromatin assembly of newly synthesized histones: distinct functions for the histone tail domains.

PubMed

Ejlassi-Lassallette, Aïda; Thiriet, Christophe

2012-02-01

The maintenance of the genome during replication requires the assembly of nucleosomes with newly synthesized histones. Achieving the deposition of newly synthesized histones in chromatin implies their transport from the cytoplasm to the nucleus at the replication sites. Several lines of evidence have revealed critical functions of the histone tail domains in these conserved cellular processes. In this review, we discuss the role of the amino termini of the nucleosome building blocks, H2A/H2B and H3/H4, in different model systems. The experimental data showed that H2A/H2B tails and H3/H4 tails display distinct functions in nuclear import and chromatin assembly. Furthermore, we describe recent studies exploiting the unique properties of the slime mold, Physarum polycephalum , that have advanced understanding of the function of the highly conserved replication-dependent diacetylation of H4.
The Canonical Immediate Early 3 Gene Product pIE611 of Mouse Cytomegalovirus Is Dispensable for Viral Replication but Mediates Transcriptional and Posttranscriptional Regulation of Viral Gene Products.

PubMed

Rattay, Stephanie; Trilling, Mirko; Megger, Dominik A; Sitek, Barbara; Meyer, Helmut E; Hengel, Hartmut; Le-Trilling, Vu Thuy Khanh

2015-08-01

Transcription of mouse cytomegalovirus (MCMV) immediate early ie1 and ie3 is controlled by the major immediate early promoter/enhancer (MIEP) and requires differential splicing. Based on complete loss of genome replication of an MCMV mutant carrying a deletion of the ie3-specific exon 5, the multifunctional IE3 protein (611 amino acids; pIE611) is considered essential for viral replication. Our analysis of ie3 transcription resulted in the identification of novel ie3 isoforms derived from alternatively spliced ie3 transcripts. Construction of an IE3-hemagglutinin (IE3-HA) virus by insertion of an in-frame HA epitope sequence allowed detection of the IE3 isoforms in infected cells, verifying that the newly identified transcripts code for proteins. This prompted the construction of an MCMV mutant lacking ie611 but retaining the coding capacity for the newly identified isoforms ie453 and ie310. Using Δie611 MCMV, we demonstrated the dispensability of the canonical ie3 gene product pIE611 for viral replication. To determine the role of pIE611 for viral gene expression during MCMV infection in an unbiased global approach, we used label-free quantitative mass spectrometry to delineate pIE611-dependent changes of the MCMV proteome. Interestingly, further analysis revealed transcriptional as well as posttranscriptional regulation of MCMV gene products by pIE611. Cytomegaloviruses are pathogenic betaherpesviruses persisting in a lifelong latency from which reactivation can occur under conditions of immunosuppression, immunoimmaturity, or inflammation. The switch from latency to reactivation requires expression of immediate early genes. Therefore, understanding of immediate early gene regulation might add insights into viral pathogenesis. The mouse cytomegalovirus (MCMV) immediate early 3 protein (611 amino acids; pIE611) is considered essential for viral replication. The identification of novel protein isoforms derived from alternatively spliced ie3 transcripts prompted the construction of an MCMV mutant lacking ie611 but retaining the coding capacity for the newly identified isoforms ie453 and ie310. Using Δie611 MCMV, we demonstrated the dispensability of the canonical ie3 gene product pIE611 for viral replication and delineated pIE611-dependent changes of the MCMV proteome. Our findings have fundamental implications for the interpretation of earlier studies on pIE3 functions and highlight the complex orchestration of MCMV gene regulation. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
Epstein-Barr virus nuclear antigen-1 is highly colocalized with interphase chromatin and its newly replicated regions in particular.

PubMed

Ito, Sayuri; Gotoh, Eisuke; Ozawa, Shigeru; Yanagi, Kazuo

2002-10-01

Epstein-Barr virus (EBV) nuclear antigen-1 (EBNA-1), which binds to both the EBV origin of replication (oriP) and metaphase chromosomes, is essential for the replication/retention and segregation/partition of oriP-containing plasmids. Here the chromosomal localization of EBNA-1 fused to green fluorescent protein (GFP-EBNA-1) is examined by confocal microscopy combined with a 'premature chromosome condensation' (PCC) procedure. Analyses show that GFP-EBNA-1 expressed in living cells that lack oriP plasmids is associated with cellular chromatin that has been condensed rapidly by the PCC procedure into identifiable forms that are unique to each phase of interphase as well as metaphase chromosomes. Studies of cellular chromosomal DNAs labelled with BrdU or Cy3-dUTP indicate that GFP-EBNA-1 colocalizes highly with the labelled, newly replicated regions of interphase chromatin in cells. These results suggest that EBNA-1 is associated not only with cellular metaphase chromosomes but also with condensing chromatin/chromosomes and probably with interphase chromatin, especially with its newly replicated regions.
High Resolution Genomic Scans Reveal Genetic Architecture Controlling Alcohol Preference in Bidirectionally Selected Rat Model.

PubMed

Lo, Chiao-Ling; Lossie, Amy C; Liang, Tiebing; Liu, Yunlong; Xuei, Xiaoling; Lumeng, Lawrence; Zhou, Feng C; Muir, William M

2016-08-01

Investigations on the influence of nature vs. nurture on Alcoholism (Alcohol Use Disorder) in human have yet to provide a clear view on potential genomic etiologies. To address this issue, we sequenced a replicated animal model system bidirectionally-selected for alcohol preference (AP). This model is uniquely suited to map genetic effects with high reproducibility, and resolution. The origin of the rat lines (an 8-way cross) resulted in small haplotype blocks (HB) with a corresponding high level of resolution. We sequenced DNAs from 40 samples (10 per line of each replicate) to determine allele frequencies and HB. We achieved ~46X coverage per line and replicate. Excessive differentiation in the genomic architecture between lines, across replicates, termed signatures of selection (SS), were classified according to gene and region. We identified SS in 930 genes associated with AP. The majority (50%) of the SS were confined to single gene regions, the greatest numbers of which were in promoters (284) and intronic regions (169) with the least in exon's (4), suggesting that differences in AP were primarily due to alterations in regulatory regions. We confirmed previously identified genes and found many new genes associated with AP. Of those newly identified genes, several demonstrated neuronal function involved in synaptic memory and reward behavior, e.g. ion channels (Kcnf1, Kcnn3, Scn5a), excitatory receptors (Grin2a, Gria3, Grip1), neurotransmitters (Pomc), and synapses (Snap29). This study not only reveals the polygenic architecture of AP, but also emphasizes the importance of regulatory elements, consistent with other complex traits.
Isolation and Characterization of Highly Replicable Hepatitis C Virus Genotype 1a Strain HCV-RMT

PubMed Central

Arai, Masaaki; Tokunaga, Yuko; Takagi, Asako; Tobita, Yoshimi; Hirata, Yuichi; Ishida, Yuji; Tateno, Chise; Kohara, Michinori

2013-01-01

Multiple genotype 1a clones have been reported, including the very first hepatitis C virus (HCV) clone called H77. The replication ability of some of these clones has been confirmed in vitro and in vivo, although this ability is somehow compromised. We now report a newly isolated genotype 1a clone, designated HCV-RMT, which has the ability to replicate efficiently in patients, chimeric mice with humanized liver, and cultured cells. An authentic subgenomic replicon cell line was established from the HCV-RMT sequence with spontaneous introduction of three adaptive mutations, which were later confirmed to be responsible for efficient replication in HuH-7 cells as both subgenomic replicon RNA and viral genome RNA. Following transfection, the HCV-RMT RNA genome with three adaptive mutations was maintained for more than 2 months in HuH-7 cells. One clone selected from the transfected cells had a high copy number, and its supernatant could infect naïve HuH-7 cells. Direct injection of wild-type HCV-RMT RNA into the liver of chimeric mice with humanized liver resulted in vigorous replication, similar to inoculation with the parental patient’s serum. A study of virus replication using HCV-RMT derivatives with various combinations of adaptive mutations revealed a clear inversely proportional relationship between in vitro and in vivo replication abilities. Thus, we suggest that HCV-RMT and its derivatives are important tools for HCV genotype 1a research and for determining the mechanism of HCV replication in vitro and in vivo. PMID:24358200
Isolation and characterization of highly replicable hepatitis C virus genotype 1a strain HCV-RMT.

PubMed

Arai, Masaaki; Tokunaga, Yuko; Takagi, Asako; Tobita, Yoshimi; Hirata, Yuichi; Ishida, Yuji; Tateno, Chise; Kohara, Michinori

2013-01-01

Multiple genotype 1a clones have been reported, including the very first hepatitis C virus (HCV) clone called H77. The replication ability of some of these clones has been confirmed in vitro and in vivo, although this ability is somehow compromised. We now report a newly isolated genotype 1a clone, designated HCV-RMT, which has the ability to replicate efficiently in patients, chimeric mice with humanized liver, and cultured cells. An authentic subgenomic replicon cell line was established from the HCV-RMT sequence with spontaneous introduction of three adaptive mutations, which were later confirmed to be responsible for efficient replication in HuH-7 cells as both subgenomic replicon RNA and viral genome RNA. Following transfection, the HCV-RMT RNA genome with three adaptive mutations was maintained for more than 2 months in HuH-7 cells. One clone selected from the transfected cells had a high copy number, and its supernatant could infect naïve HuH-7 cells. Direct injection of wild-type HCV-RMT RNA into the liver of chimeric mice with humanized liver resulted in vigorous replication, similar to inoculation with the parental patient's serum. A study of virus replication using HCV-RMT derivatives with various combinations of adaptive mutations revealed a clear inversely proportional relationship between in vitro and in vivo replication abilities. Thus, we suggest that HCV-RMT and its derivatives are important tools for HCV genotype 1a research and for determining the mechanism of HCV replication in vitro and in vivo.
Whole-genome analysis of genetic recombination of hepatitis delta virus: molecular domain in delta antigen determining trans-activating efficiency.

PubMed

Chao, Mei; Lin, Chia-Chi; Lin, Feng-Ming; Li, Hsin-Pai; Iang, Shan-Bei

2015-12-01

Hepatitis delta virus (HDV) is the only animal RNA virus that has an unbranched rod-like genome with ribozyme activity and is replicated by host RNA polymerase. HDV RNA recombination was previously demonstrated in patients and in cultured cells by analysis of a region corresponding to the C terminus of the delta antigen (HDAg), the only viral-encoded protein. Here, a whole-genome recombination map of HDV was constructed using an experimental system in which two HDV-1 sequences were co-transfected into cultured cells and the recombinants were analysed by sequencing of cloned reverse transcription-PCR products. Fifty homologous recombinants with 60 crossovers mapping to 22 junctions were identified from 200 analysed clones. Small HDAg chimeras harbouring a junction newly detected in the recombination map were then constructed. The results further indicated that the genome-replication level of HDV was sensitive to the sixth amino acid within the N-terminal 22 aa of HDAg. Therefore, the recombination map established in this study provided a tool for not only understanding HDV RNA recombination, but also elucidating the related mechanisms, such as molecular elements responsible for the trans-activation levels of the small HDAg.
Micronuclear DNA of Oxytricha nova contains sequences with autonomously replicating activity in Saccharomyces cerevisiae.

PubMed Central

Colombo, M M; Swanton, M T; Donini, P; Prescott, D M

1984-01-01

Oxytricha nova is a hypotrichous ciliate with micronuclei and macronuclei. Micronuclei, which contain large, chromosomal-sized DNA, are genetically inert but undergo meiosis and exchange during cell mating. Macronuclei, which contain only small, gene-sized DNA molecules, provide all of the nuclear RNA needed to run the cell. After cell mating the macronucleus is derived from a micronucleus, a derivation that includes excision of the genes from chromosomes and elimination of the remaining DNA. The eliminated DNA includes all of the repetitious sequences and approximately 95% of the unique sequences. We cloned large restriction fragments from the micronucleus that confer replication ability on a replication-deficient plasmid in Saccharomyces cerevisiae. Sequences that confer replication ability are called autonomously replicating sequences. The frequency and effectiveness of autonomously replicating sequences in micronuclear DNA are similar to those reported for DNAs of other organisms introduced into yeast cells. Of the 12 micronuclear fragments with autonomously replicating sequence activity, 9 also showed homology to macronuclear DNA, indicating that they contain a macronuclear gene sequence. We conclude from this that autonomously replicating sequence activity is nonrandomly distributed throughout micronuclear DNA and is preferentially associated with those regions of micronuclear DNA that contain genes. Images PMID:6092934
Characterization of a novel insect-specific flavivirus from Brazil: Potential for inhibition of infection of arthropod cells with medically important flaviviruses.

DOE PAGES

Kenney, Joan L.; Solberg, Owen D.; Langevin, Stanley A.; ...

2014-01-12

In the past decade, there has been an upsurge in the number of newly described insect-specific flaviviruses isolated pan-globally. We recently described the isolation of a novel flavivirus (tentatively designated ‘Nhumirim virus’; NHUV) that represents an example of a unique subset of apparently insect-specific viruses that phylogenetically affiliate with dual-host mosquito-borne flaviviruses despite appearing to be limited to replication in mosquito cells. We characterized the in vitro growth potential and 3' untranslated region (UTR) sequence homology with alternative flaviviruses, and evaluated the virus’s capacity to suppress replication of representative Culex spp.-vectored pathogenic flaviviruses in mosquito cells. Only mosquito cell linesmore » were found to support NHUV replication, further reinforcing the insect-specific phenotype of this virus. Analysis of the sequence and predicted RNA secondary structures of the 3' UTR indicated NHUV to be most similar to viruses within the yellow fever serogroup and Japanese encephalitis serogroup, and viruses in the tick-borne flavivirus clade. NHUV was found to share the fewest conserved sequence elements when compared with traditional insect-specific flaviviruses. This suggests that, despite apparently being insect specific, this virus probably diverged from an ancestral mosquito-borne flavivirus. Co-infection experiments indicated that prior or concurrent infection of mosquito cells with NHUV resulted in a significant reduction in virus production of West Nile virus (WNV), St Louis encephalitis virus (SLEV) and Japanese encephalitis virus. As a result, the inhibitory effect was most effective against WNV and SLEV with over a 106-fold and 104-fold reduction in peak titres, respectively.« less
Characterization of a novel insect-specific flavivirus from Brazil: Potential for inhibition of infection of arthropod cells with medically important flaviviruses.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenney, Joan L.; Solberg, Owen D.; Langevin, Stanley A.

In the past decade, there has been an upsurge in the number of newly described insect-specific flaviviruses isolated pan-globally. We recently described the isolation of a novel flavivirus (tentatively designated ‘Nhumirim virus’; NHUV) that represents an example of a unique subset of apparently insect-specific viruses that phylogenetically affiliate with dual-host mosquito-borne flaviviruses despite appearing to be limited to replication in mosquito cells. We characterized the in vitro growth potential and 3' untranslated region (UTR) sequence homology with alternative flaviviruses, and evaluated the virus’s capacity to suppress replication of representative Culex spp.-vectored pathogenic flaviviruses in mosquito cells. Only mosquito cell linesmore » were found to support NHUV replication, further reinforcing the insect-specific phenotype of this virus. Analysis of the sequence and predicted RNA secondary structures of the 3' UTR indicated NHUV to be most similar to viruses within the yellow fever serogroup and Japanese encephalitis serogroup, and viruses in the tick-borne flavivirus clade. NHUV was found to share the fewest conserved sequence elements when compared with traditional insect-specific flaviviruses. This suggests that, despite apparently being insect specific, this virus probably diverged from an ancestral mosquito-borne flavivirus. Co-infection experiments indicated that prior or concurrent infection of mosquito cells with NHUV resulted in a significant reduction in virus production of West Nile virus (WNV), St Louis encephalitis virus (SLEV) and Japanese encephalitis virus. As a result, the inhibitory effect was most effective against WNV and SLEV with over a 106-fold and 104-fold reduction in peak titres, respectively.« less
Characterization of a novel insect-specific flavivirus from Brazil: potential for inhibition of infection of arthropod cells with medically important flaviviruses

PubMed Central

Kenney, Joan L.; Solberg, Owen D.; Langevin, Stanley A.; Brault, Aaron C.

2015-01-01

In the past decade there has been an upsurge in the number of newly described insect-specific flaviviruses isolated pan-globally. We recently described the isolation of a novel flavivirus (tentatively designated “Nhumirim virus”; NHUV) (Pauvolid-Correa et al., in review) that represents an example of a unique subset of apparently insect-specific viruses that phylogenetically affiliate with dual-host mosquito-borne flaviviruses despite appearing to be limited to replication in mosquito cells. We characterized the in vitro growth potential, 3’ untranslated region (UTR) sequence homology with alternative flaviviruses, and evaluated the virus’s capacity to suppress replication of representative Culex spp. vectored pathogenic flaviviruses in mosquito cells. Only mosquito cell lines were found to support NHUV replication, further reinforcing the insect-specific phenotype of this virus. Analysis of the sequence and predicted RNA secondary structures of the 3’ UTR indicate NHUV to be most similar to viruses within the yellow fever serogroup, Japanese encephalitis serogroup, and viruses in the tick-borne flavivirus clade. NHUV was found to share the fewest conserved sequence elements when compared to traditional insect-specific flaviviruses. This suggests that, despite being apparently insect-specific, this virus likely diverged from an ancestral mosquito-borne flavivirus. Co-infection experiments indicated that prior or concurrent infection of mosquito cells with NHUV resulted in significant reduction in viral production of West Nile virus (WNV), St. Louis encephalitis virus (SLEV) and Japanese encephalitis virus. The inhibitory effect was most effective against WNV and SLEV with over a million-fold and 10,000-fold reduction in peak titers, respectively. PMID:25146007
Division-induced DNA double strand breaks in the chromosome terminus region of Escherichia coli lacking RecBCD DNA repair enzyme

PubMed Central

Durand, Adeline; Desfontaines, Jean-Michel; Iurchenko, Ielyzaveta; Auger, Hélène; Leach, David R. F.

2017-01-01

Marker frequency analysis of the Escherichia coli recB mutant chromosome has revealed a deficit of DNA in a specific zone of the terminus, centred on the dif/TerC region. Using fluorescence microscopy of a marked chromosomal site, we show that the dif region is lost after replication completion, at the time of cell division, in one daughter cell only, and that the phenomenon is transmitted to progeny. Analysis by marker frequency and microscopy shows that the position of DNA loss is not defined by the replication fork merging point since it still occurs in the dif/TerC region when the replication fork trap is displaced in strains harbouring ectopic Ter sites. Terminus DNA loss in the recB mutant is also independent of dimer resolution by XerCD at dif and of Topo IV action close to dif. It occurs in the terminus region, at the point of inversion of the GC skew, which is also the point of convergence of specific sequence motifs like KOPS and Chi sites, regardless of whether the convergence of GC skew is at dif (wild-type) or a newly created sequence. In the absence of FtsK-driven DNA translocation, terminus DNA loss is less precisely targeted to the KOPS convergence sequence, but occurs at a similar frequency and follows the same pattern as in FtsK+ cells. Importantly, using ftsIts, ftsAts division mutants and cephalexin treated cells, we show that DNA loss of the dif region in the recB mutant is decreased by the inactivation of cell division. We propose that it results from septum-induced chromosome breakage, and largely contributes to the low viability of the recB mutant. PMID:28968392
De novo identification of replication-timing domains in the human genome by deep learning.

PubMed

Liu, Feng; Ren, Chao; Li, Hao; Zhou, Pingkun; Bo, Xiaochen; Shu, Wenjie

2016-03-01

The de novo identification of the initiation and termination zones-regions that replicate earlier or later than their upstream and downstream neighbours, respectively-remains a key challenge in DNA replication. Building on advances in deep learning, we developed a novel hybrid architecture combining a pre-trained, deep neural network and a hidden Markov model (DNN-HMM) for the de novo identification of replication domains using replication timing profiles. Our results demonstrate that DNN-HMM can significantly outperform strong, discriminatively trained Gaussian mixture model-HMM (GMM-HMM) systems and other six reported methods that can be applied to this challenge. We applied our trained DNN-HMM to identify distinct replication domain types, namely the early replication domain (ERD), the down transition zone (DTZ), the late replication domain (LRD) and the up transition zone (UTZ), using newly replicated DNA sequencing (Repli-Seq) data across 15 human cells. A subsequent integrative analysis revealed that these replication domains harbour unique genomic and epigenetic patterns, transcriptional activity and higher-order chromosomal structure. Our findings support the 'replication-domain' model, which states (1) that ERDs and LRDs, connected by UTZs and DTZs, are spatially compartmentalized structural and functional units of higher-order chromosomal structure, (2) that the adjacent DTZ-UTZ pairs form chromatin loops and (3) that intra-interactions within ERDs and LRDs tend to be short-range and long-range, respectively. Our model reveals an important chromatin organizational principle of the human genome and represents a critical step towards understanding the mechanisms regulating replication timing. Our DNN-HMM method and three additional algorithms can be freely accessed at https://github.com/wenjiegroup/DNN-HMM The replication domain regions identified in this study are available in GEO under the accession ID GSE53984. shuwj@bmi.ac.cn or boxc@bmi.ac.cn Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press.
DAMe: a toolkit for the initial processing of datasets with PCR replicates of double-tagged amplicons for DNA metabarcoding analyses.

PubMed

Zepeda-Mendoza, Marie Lisandra; Bohmann, Kristine; Carmona Baez, Aldo; Gilbert, M Thomas P

2016-05-03

DNA metabarcoding is an approach for identifying multiple taxa in an environmental sample using specific genetic loci and taxa-specific primers. When combined with high-throughput sequencing it enables the taxonomic characterization of large numbers of samples in a relatively time- and cost-efficient manner. One recent laboratory development is the addition of 5'-nucleotide tags to both primers producing double-tagged amplicons and the use of multiple PCR replicates to filter erroneous sequences. However, there is currently no available toolkit for the straightforward analysis of datasets produced in this way. We present DAMe, a toolkit for the processing of datasets generated by double-tagged amplicons from multiple PCR replicates derived from an unlimited number of samples. Specifically, DAMe can be used to (i) sort amplicons by tag combination, (ii) evaluate PCR replicates dissimilarity, and (iii) filter sequences derived from sequencing/PCR errors, chimeras, and contamination. This is attained by calculating the following parameters: (i) sequence content similarity between the PCR replicates from each sample, (ii) reproducibility of each unique sequence across the PCR replicates, and (iii) copy number of the unique sequences in each PCR replicate. We showcase the insights that can be obtained using DAMe prior to taxonomic assignment, by applying it to two real datasets that vary in their complexity regarding number of samples, sequencing libraries, PCR replicates, and used tag combinations. Finally, we use a third mock dataset to demonstrate the impact and importance of filtering the sequences with DAMe. DAMe allows the user-friendly manipulation of amplicons derived from multiple samples with PCR replicates built in a single or multiple sequencing libraries. It allows the user to: (i) collapse amplicons into unique sequences and sort them by tag combination while retaining the sample identifier and copy number information, (ii) identify sequences carrying unused tag combinations, (iii) evaluate the comparability of PCR replicates of the same sample, and (iv) filter tagged amplicons from a number of PCR replicates using parameters of minimum length, copy number, and reproducibility across the PCR replicates. This enables an efficient analysis of complex datasets, and ultimately increases the ease of handling datasets from large-scale studies.
DNA Replication Profiling Using Deep Sequencing.

PubMed

Saayman, Xanita; Ramos-Pérez, Cristina; Brown, Grant W

2018-01-01

Profiling of DNA replication during progression through S phase allows a quantitative snap-shot of replication origin usage and DNA replication fork progression. We present a method for using deep sequencing data to profile DNA replication in S. cerevisiae.
A Survey of Protein Structures from Archaeal Viruses

PubMed Central

Dellas, Nikki; Lawrence, C. Martin; Young, Mark J.

2013-01-01

Viruses that infect the third domain of life, Archaea, are a newly emerging field of interest. To date, all characterized archaeal viruses infect archaea that thrive in extreme conditions, such as halophilic, hyperthermophilic, and methanogenic environments. Viruses in general, especially those replicating in extreme environments, contain highly mosaic genomes with open reading frames (ORFs) whose sequences are often dissimilar to all other known ORFs. It has been estimated that approximately 85% of virally encoded ORFs do not match known sequences in the nucleic acid databases, and this percentage is even higher for archaeal viruses (typically 90%–100%). This statistic suggests that either virus genomes represent a larger segment of sequence space and/or that viruses encode genes of novel fold and/or function. Because the overall three-dimensional fold of a protein evolves more slowly than its sequence, efforts have been geared toward structural characterization of proteins encoded by archaeal viruses in order to gain insight into their potential functions. In this short review, we provide multiple examples where structural characterization of archaeal viral proteins has indeed provided significant functional and evolutionary insight. PMID:25371334
Transcriptome sequencing of newly molted adult female cattle ticks, Rhipicephalus microplus: Raw Illumina reads.

USDA-ARS?s Scientific Manuscript database

Illumina paired end oligo-dT sequencing technology was used to sequence the transcriptome from newly molted adult females from the cattle tick, Rhipicephalus microplus. These samples include newly molted unfed whole adult females, newly molted whole adult females feeding for 2 hours on a bovine host...
A Comparative Encyclopedia of DNA Elements in the Mouse Genome

PubMed Central

Yue, Feng; Cheng, Yong; Breschi, Alessandra; Vierstra, Jeff; Wu, Weisheng; Ryba, Tyrone; Sandstrom, Richard; Ma, Zhihai; Davis, Carrie; Pope, Benjamin D.; Shen, Yin; Pervouchine, Dmitri D.; Djebali, Sarah; Thurman, Bob; Kaul, Rajinder; Rynes, Eric; Kirilusha, Anthony; Marinov, Georgi K.; Williams, Brian A.; Trout, Diane; Amrhein, Henry; Fisher-Aylor, Katherine; Antoshechkin, Igor; DeSalvo, Gilberto; See, Lei-Hoon; Fastuca, Meagan; Drenkow, Jorg; Zaleski, Chris; Dobin, Alex; Prieto, Pablo; Lagarde, Julien; Bussotti, Giovanni; Tanzer, Andrea; Denas, Olgert; Li, Kanwei; Bender, M. A.; Zhang, Miaohua; Byron, Rachel; Groudine, Mark T.; McCleary, David; Pham, Long; Ye, Zhen; Kuan, Samantha; Edsall, Lee; Wu, Yi-Chieh; Rasmussen, Matthew D.; Bansal, Mukul S.; Keller, Cheryl A.; Morrissey, Christapher S.; Mishra, Tejaswini; Jain, Deepti; Dogan, Nergiz; Harris, Robert S.; Cayting, Philip; Kawli, Trupti; Boyle, Alan P.; Euskirchen, Ghia; Kundaje, Anshul; Lin, Shin; Lin, Yiing; Jansen, Camden; Malladi, Venkat S.; Cline, Melissa S.; Erickson, Drew T.; Kirkup, Vanessa M; Learned, Katrina; Sloan, Cricket A.; Rosenbloom, Kate R.; de Sousa, Beatriz Lacerda; Beal, Kathryn; Pignatelli, Miguel; Flicek, Paul; Lian, Jin; Kahveci, Tamer; Lee, Dongwon; Kent, W. James; Santos, Miguel Ramalho; Herrero, Javier; Notredame, Cedric; Johnson, Audra; Vong, Shinny; Lee, Kristen; Bates, Daniel; Neri, Fidencio; Diegel, Morgan; Canfield, Theresa; Sabo, Peter J.; Wilken, Matthew S.; Reh, Thomas A.; Giste, Erika; Shafer, Anthony; Kutyavin, Tanya; Haugen, Eric; Dunn, Douglas; Reynolds, Alex P.; Neph, Shane; Humbert, Richard; Hansen, R. Scott; De Bruijn, Marella; Selleri, Licia; Rudensky, Alexander; Josefowicz, Steven; Samstein, Robert; Eichler, Evan E.; Orkin, Stuart H.; Levasseur, Dana; Papayannopoulou, Thalia; Chang, Kai-Hsin; Skoultchi, Arthur; Gosh, Srikanta; Disteche, Christine; Treuting, Piper; Wang, Yanli; Weiss, Mitchell J.; Blobel, Gerd A.; Good, Peter J.; Lowdon, Rebecca F.; Adams, Leslie B.; Zhou, Xiao-Qiao; Pazin, Michael J.; Feingold, Elise A.; Wold, Barbara; Taylor, James; Kellis, Manolis; Mortazavi, Ali; Weissman, Sherman M.; Stamatoyannopoulos, John; Snyder, Michael P.; Guigo, Roderic; Gingeras, Thomas R.; Gilbert, David M.; Hardison, Ross C.; Beer, Michael A.; Ren, Bing

2014-01-01

Summary As the premier model organism in biomedical research, the laboratory mouse shares the majority of protein-coding genes with humans, yet the two mammals differ in significant ways. To gain greater insights into both shared and species-specific transcriptional and cellular regulatory programs in the mouse, the Mouse ENCODE Consortium has mapped transcription, DNase I hypersensitivity, transcription factor binding, chromatin modifications, and replication domains throughout the mouse genome in diverse cell and tissue types. By comparing with the human genome, we not only confirm substantial conservation in the newly annotated potential functional sequences, but also find a large degree of divergence of other sequences involved in transcriptional regulation, chromatin state and higher order chromatin organization. Our results illuminate the wide range of evolutionary forces acting on genes and their regulatory regions, and provide a general resource for research into mammalian biology and mechanisms of human diseases. PMID:25409824
A comparative encyclopedia of DNA elements in the mouse genome.

PubMed

Yue, Feng; Cheng, Yong; Breschi, Alessandra; Vierstra, Jeff; Wu, Weisheng; Ryba, Tyrone; Sandstrom, Richard; Ma, Zhihai; Davis, Carrie; Pope, Benjamin D; Shen, Yin; Pervouchine, Dmitri D; Djebali, Sarah; Thurman, Robert E; Kaul, Rajinder; Rynes, Eric; Kirilusha, Anthony; Marinov, Georgi K; Williams, Brian A; Trout, Diane; Amrhein, Henry; Fisher-Aylor, Katherine; Antoshechkin, Igor; DeSalvo, Gilberto; See, Lei-Hoon; Fastuca, Meagan; Drenkow, Jorg; Zaleski, Chris; Dobin, Alex; Prieto, Pablo; Lagarde, Julien; Bussotti, Giovanni; Tanzer, Andrea; Denas, Olgert; Li, Kanwei; Bender, M A; Zhang, Miaohua; Byron, Rachel; Groudine, Mark T; McCleary, David; Pham, Long; Ye, Zhen; Kuan, Samantha; Edsall, Lee; Wu, Yi-Chieh; Rasmussen, Matthew D; Bansal, Mukul S; Kellis, Manolis; Keller, Cheryl A; Morrissey, Christapher S; Mishra, Tejaswini; Jain, Deepti; Dogan, Nergiz; Harris, Robert S; Cayting, Philip; Kawli, Trupti; Boyle, Alan P; Euskirchen, Ghia; Kundaje, Anshul; Lin, Shin; Lin, Yiing; Jansen, Camden; Malladi, Venkat S; Cline, Melissa S; Erickson, Drew T; Kirkup, Vanessa M; Learned, Katrina; Sloan, Cricket A; Rosenbloom, Kate R; Lacerda de Sousa, Beatriz; Beal, Kathryn; Pignatelli, Miguel; Flicek, Paul; Lian, Jin; Kahveci, Tamer; Lee, Dongwon; Kent, W James; Ramalho Santos, Miguel; Herrero, Javier; Notredame, Cedric; Johnson, Audra; Vong, Shinny; Lee, Kristen; Bates, Daniel; Neri, Fidencio; Diegel, Morgan; Canfield, Theresa; Sabo, Peter J; Wilken, Matthew S; Reh, Thomas A; Giste, Erika; Shafer, Anthony; Kutyavin, Tanya; Haugen, Eric; Dunn, Douglas; Reynolds, Alex P; Neph, Shane; Humbert, Richard; Hansen, R Scott; De Bruijn, Marella; Selleri, Licia; Rudensky, Alexander; Josefowicz, Steven; Samstein, Robert; Eichler, Evan E; Orkin, Stuart H; Levasseur, Dana; Papayannopoulou, Thalia; Chang, Kai-Hsin; Skoultchi, Arthur; Gosh, Srikanta; Disteche, Christine; Treuting, Piper; Wang, Yanli; Weiss, Mitchell J; Blobel, Gerd A; Cao, Xiaoyi; Zhong, Sheng; Wang, Ting; Good, Peter J; Lowdon, Rebecca F; Adams, Leslie B; Zhou, Xiao-Qiao; Pazin, Michael J; Feingold, Elise A; Wold, Barbara; Taylor, James; Mortazavi, Ali; Weissman, Sherman M; Stamatoyannopoulos, John A; Snyder, Michael P; Guigo, Roderic; Gingeras, Thomas R; Gilbert, David M; Hardison, Ross C; Beer, Michael A; Ren, Bing

2014-11-20

The laboratory mouse shares the majority of its protein-coding genes with humans, making it the premier model organism in biomedical research, yet the two mammals differ in significant ways. To gain greater insights into both shared and species-specific transcriptional and cellular regulatory programs in the mouse, the Mouse ENCODE Consortium has mapped transcription, DNase I hypersensitivity, transcription factor binding, chromatin modifications and replication domains throughout the mouse genome in diverse cell and tissue types. By comparing with the human genome, we not only confirm substantial conservation in the newly annotated potential functional sequences, but also find a large degree of divergence of sequences involved in transcriptional regulation, chromatin state and higher order chromatin organization. Our results illuminate the wide range of evolutionary forces acting on genes and their regulatory regions, and provide a general resource for research into mammalian biology and mechanisms of human diseases.
Selection of unadapted, pathogenic SHIVs encoding newly transmitted HIV-1 envelope proteins.

PubMed

Del Prete, Gregory Q; Ailers, Braiden; Moldt, Brian; Keele, Brandon F; Estes, Jacob D; Rodriguez, Anthony; Sampias, Marissa; Oswald, Kelli; Fast, Randy; Trubey, Charles M; Chertova, Elena; Smedley, Jeremy; LaBranche, Celia C; Montefiori, David C; Burton, Dennis R; Shaw, George M; Markowitz, Marty; Piatak, Michael; KewalRamani, Vineet N; Bieniasz, Paul D; Lifson, Jeffrey D; Hatziioannou, Theodora

2014-09-10

Infection of macaques with chimeric viruses based on SIVMAC but expressing the HIV-1 envelope (Env) glycoproteins (SHIVs) remains the most powerful model for evaluating prevention and therapeutic strategies against AIDS. Unfortunately, only a few SHIVs are currently available. Furthermore, their generation has required extensive adaptation of the HIV-1 Env sequences in macaques so they may not accurately represent HIV-1 Env proteins circulating in humans, potentially limiting their translational utility. We developed a strategy for generating large numbers of SHIV constructs expressing Env proteins from newly transmitted HIV-1 strains. By inoculating macaques with cocktails of multiple SHIV variants, we selected SHIVs that can replicate and cause AIDS-like disease in immunologically intact rhesus macaques without requiring animal-to-animal passage. One of these SHIVs could be transmitted mucosally. We demonstrate the utility of the SHIVs generated by this method for evaluating neutralizing antibody administration as a protection against mucosal SHIV challenge. Copyright © 2014 Elsevier Inc. All rights reserved.

Human CST Facilitates Genome-wide RAD51 Recruitment to GC-Rich Repetitive Sequences in Response to Replication Stress.

PubMed

Chastain, Megan; Zhou, Qing; Shiva, Olga; Fadri-Moskwik, Maria; Whitmore, Leanne; Jia, Pingping; Dai, Xueyu; Huang, Chenhui; Ye, Ping; Chai, Weihang

2016-08-02

The telomeric CTC1/STN1/TEN1 (CST) complex has been implicated in promoting replication recovery under replication stress at genomic regions, yet its precise role is unclear. Here, we report that STN1 is enriched at GC-rich repetitive sequences genome-wide in response to hydroxyurea (HU)-induced replication stress. STN1 deficiency exacerbates the fragility of these sequences under replication stress, resulting in chromosome fragmentation. We find that upon fork stalling, CST proteins form distinct nuclear foci that colocalize with RAD51. Furthermore, replication stress induces physical association of CST with RAD51 in an ATR-dependent manner. Strikingly, CST deficiency diminishes HU-induced RAD51 foci formation and reduces RAD51 recruitment to telomeres and non-telomeric GC-rich fragile sequences. Collectively, our findings establish that CST promotes RAD51 recruitment to GC-rich repetitive sequences in response to replication stress to facilitate replication restart, thereby providing insights into the mechanism underlying genome stability maintenance. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.
Structure, replication efficiency and fragility of yeast ARS elements.

PubMed

Dhar, Manoj K; Sehgal, Shelly; Kaul, Sanjana

2012-05-01

DNA replication in eukaryotes initiates at specific sites known as origins of replication, or replicators. These replication origins occur throughout the genome, though the propensity of their occurrence depends on the type of organism. In eukaryotes, zones of initiation of replication spanning from about 100 to 50,000 base pairs have been reported. The characteristics of eukaryotic replication origins are best understood in the budding yeast Saccharomyces cerevisiae, where some autonomously replicating sequences, or ARS elements, confer origin activity. ARS elements are short DNA sequences of a few hundred base pairs, identified by their efficiency at initiating a replication event when cloned in a plasmid. ARS elements, although structurally diverse, maintain a basic structure composed of three domains, A, B and C. Domain A is comprised of a consensus sequence designated ACS (ARS consensus sequence), while the B domain has the DNA unwinding element and the C domain is important for DNA-protein interactions. Although there are ∼400 ARS elements in the yeast genome, not all of them are active origins of replication. Different groups within the genus Saccharomyces have ARS elements as components of replication origin. The present paper provides a comprehensive review of various aspects of ARSs, starting from their structural conservation to sequence thermodynamics. All significant and conserved functional sequence motifs within different types of ARS elements have been extensively described. Issues like silencing at ARSs, their inherent fragility and factors governing their replication efficiency have also been addressed. Progress in understanding crucial components associated with the replication machinery and timing at these ARS elements is discussed in the section entitled "The replicon revisited". Copyright © 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.
Identification and characterization of ARS-like sequences as putative origin(s) of replication in human malaria parasite Plasmodium falciparum.

PubMed

Agarwal, Meetu; Bhowmick, Krishanu; Shah, Kushal; Krishnamachari, Annangarachari; Dhar, Suman Kumar

2017-08-01

DNA replication is a fundamental process in genome maintenance, and initiates from several genomic sites (origins) in eukaryotes. In Saccharomyces cerevisiae, conserved sequences known as autonomously replicating sequences (ARSs) provide a landing pad for the origin recognition complex (ORC), leading to replication initiation. Although origins from higher eukaryotes share some common sequence features, the definitive genomic organization of these sites remains elusive. The human malaria parasite Plasmodium falciparum undergoes multiple rounds of DNA replication; therefore, control of initiation events is crucial to ensure proper replication. However, the sites of DNA replication initiation and the mechanism by which replication is initiated are poorly understood. Here, we have identified and characterized putative origins in P. falciparum by bioinformatics analyses and experimental approaches. An autocorrelation measure method was initially used to search for regions with marked fluctuation (dips) in the chromosome, which we hypothesized might contain potential origins. Indeed, S. cerevisiae ARS consensus sequences were found in dip regions. Several of these P. falciparum sequences were validated with chromatin immunoprecipitation-quantitative PCR, nascent strand abundance and a plasmid stability assay. Subsequently, the same sequences were used in yeast to confirm their potential as origins in vivo. Our results identify the presence of functional ARSs in P. falciparum and provide meaningful insights into replication origins in these deadly parasites. These data could be useful in designing transgenic vectors with improved stability for transfection in P. falciparum. © 2017 Federation of European Biochemical Societies.
Three-dimensional architecture of tick-borne encephalitis virus replication sites and trafficking of the replicated RNA.

PubMed

Miorin, Lisa; Romero-Brey, Inés; Maiuri, Paolo; Hoppe, Simone; Krijnse-Locker, Jacomine; Bartenschlager, Ralf; Marcello, Alessandro

2013-06-01

Flavivirus replication is accompanied by the rearrangement of cellular membranes that may facilitate viral genome replication and protect viral components from host cell responses. The topological organization of viral replication sites and the fate of replicated viral RNA are not fully understood. We exploited electron microscopy to map the organization of tick-borne encephalitis virus (TBEV) replication compartments in infected cells and in cells transfected with a replicon. Under both conditions, 80-nm vesicles were seen within the lumen of the endoplasmic reticulum (ER) that in infected cells also contained virions. By electron tomography, the vesicles appeared as invaginations of the ER membrane, displaying a pore that could enable release of newly synthesized viral RNA into the cytoplasm. To track the fate of TBEV RNA, we took advantage of our recently developed method of viral RNA fluorescent tagging for live-cell imaging combined with bleaching techniques. TBEV RNA was found outside virus-induced vesicles either associated to ER membranes or free to move within a defined area of juxtaposed ER cisternae. From our results, we propose a biologically relevant model of the possible topological organization of flavivirus replication compartments composed of replication vesicles and a confined extravesicular space where replicated viral RNA is retained. Hence, TBEV modifies the ER membrane architecture to provide a protected environment for viral replication and for the maintenance of newly replicated RNA available for subsequent steps of the virus life cycle.
Competitive replication kinetics and pathogenicity in pigs co-infected with historical and newly invading classical swine fever viruses.

PubMed

Huang, Yu-Liang; Deng, Ming-Chung; Tsai, Kuo-Jung; Liu, Hsin-Meng; Huang, Chin-Cheng; Wang, Fun-In; Chang, Chia-Yi

2017-01-15

Classical swine fever (CSF), an economically important and highly contagious disease of pigs, is caused by classical swine fever virus (CSFV). In Taiwan, CSFVs from field outbreaks belong to two distinct genotypes. The historical genotype 3.4 dominated from the 1920s to 1996, and since 1996, the newly invading genotype 2.1 has dominated. To explain the phenomenon of this virus shift in the field, representative viruses belonging to genotypes 2.1 and 3.4 were either inoculated alone (single infection) or co-inoculated (co-infection), both in vivo and in vitro, to compare the virus replication and pathogenesis. In pigs co-infected with the genotype 2.1 TD/96/TWN strain and the genotype 3.4 94.4/IL/94/TWN strain, the newly invading genotype 2.1 was detected earlier in the blood, oral fluid, and feces, and the viral loads were consistently and significantly higher than that of the historical genotype 3.4. In cell cultures, the ratio of secreted virus to cell-associated virus of the genotype 2.1 strain was higher than that of the genotype 3.4 strain. This study is the first to demonstrate a possible explanation of virus shift in the field, wherein the newly invading genotype 2.1 replicates more efficiently than did genotype 3.4 and outcompetes the replication and pathogenicity of genotype 3.4 in pigs in the field. Copyright © 2016 Elsevier B.V. All rights reserved.
Selection of Optimal Polypurine Tract Region Sequences during Moloney Murine Leukemia Virus Replication

PubMed Central

Robson, Nicole D.; Telesnitsky, Alice

2000-01-01

Retrovirus plus-strand synthesis is primed by a cleavage remnant of the polypurine tract (PPT) region of viral RNA. In this study, we tested replication properties for Moloney murine leukemia viruses with targeted mutations in the PPT and in conserved sequences upstream, as well as for pools of mutants with randomized sequences in these regions. The importance of maintaining some purine residues within the PPT was indicated both by examining the evolution of random PPT pools and from the replication properties of targeted mutants. Although many different PPT sequences could support efficient replication and one mutant that contained two differences in the core PPT was found to replicate as well as the wild type, some sequences in the core PPT clearly conferred advantages over others. Contributions of sequences upstream of the core PPT were examined with deletion mutants. A conserved T-stretch within the upstream sequence was examined in detail and found to be unimportant to helper functions. Evolution of virus pools containing randomized T-stretch sequences demonstrated marked preference for the wild-type sequence in six of its eight positions. These findings demonstrate that maintenance of the T-rich element is more important to viral replication than is maintenance of the core PPT. PMID:11044073
Ebolaviruses: New roles for old proteins.

PubMed

Cantoni, Diego; Rossman, Jeremy S

2018-05-01

In 2014, the world witnessed the largest Ebolavirus outbreak in recorded history. The subsequent humanitarian effort spurred extensive research, significantly enhancing our understanding of ebolavirus replication and pathogenicity. The main functions of each ebolavirus protein have been studied extensively since the discovery of the virus in 1976; however, the recent expansion of ebolavirus research has led to the discovery of new protein functions. These newly discovered roles are revealing new mechanisms of virus replication and pathogenicity, whilst enhancing our understanding of the broad functions of each ebolavirus viral protein (VP). Many of these new functions appear to be unrelated to the protein's primary function during virus replication. Such new functions range from bystander T-lymphocyte death caused by VP40-secreted exosomes to new roles for VP24 in viral particle formation. This review highlights the newly discovered roles of ebolavirus proteins in order to provide a more encompassing view of ebolavirus replication and pathogenicity.
Ebolaviruses: New roles for old proteins

PubMed Central

2018-01-01

In 2014, the world witnessed the largest Ebolavirus outbreak in recorded history. The subsequent humanitarian effort spurred extensive research, significantly enhancing our understanding of ebolavirus replication and pathogenicity. The main functions of each ebolavirus protein have been studied extensively since the discovery of the virus in 1976; however, the recent expansion of ebolavirus research has led to the discovery of new protein functions. These newly discovered roles are revealing new mechanisms of virus replication and pathogenicity, whilst enhancing our understanding of the broad functions of each ebolavirus viral protein (VP). Many of these new functions appear to be unrelated to the protein’s primary function during virus replication. Such new functions range from bystander T-lymphocyte death caused by VP40-secreted exosomes to new roles for VP24 in viral particle formation. This review highlights the newly discovered roles of ebolavirus proteins in order to provide a more encompassing view of ebolavirus replication and pathogenicity. PMID:29723187
Mitochondrial nucleoid clusters protect newly synthesized mtDNA during Doxorubicin- and Ethidium Bromide-induced mitochondrial stress

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alán, Lukáš, E-mail: lukas.alan@fgu.cas.cz; Špaček

Mitochondrial DNA (mtDNA) is compacted in ribonucleoprotein complexes called nucleoids, which can divide or move within the mitochondrial network. Mitochondrial nucleoids are able to aggregate into clusters upon reaction with intercalators such as the mtDNA depletion agent Ethidium Bromide (EB) or anticancer drug Doxorobicin (DXR). However, the exact mechanism of nucleoid clusters formation remains unknown. Resolving these processes may help to elucidate the mechanisms of DXR-induced cardiotoxicity. Therefore, we addressed the role of two key nucleoid proteins; mitochondrial transcription factor A (TFAM) and mitochondrial single-stranded binding protein (mtSSB); in the formation of mitochondrial nucleoid clusters during the action of intercalators.more » We found that both intercalators cause numerous aberrations due to perturbing their native status. By blocking mtDNA replication, both agents also prevented mtDNA association with TFAM, consequently causing nucleoid aggregation into large nucleoid clusters enriched with TFAM, co-existing with the normal nucleoid population. In the later stages of intercalation (> 48 h), TFAM levels were reduced to 25%. In contrast, mtSSB was released from mtDNA and freely distributed within the mitochondrial network. Nucleoid clusters mostly contained nucleoids with newly replicated mtDNA, however the nucleoid population which was not in replication mode remained outside the clusters. Moreover, the nucleoid clusters were enriched with p53, an anti-oncogenic gatekeeper. We suggest that mitochondrial nucleoid clustering is a mechanism for protecting nucleoids with newly replicated DNA against intercalators mediating genotoxic stress. These results provide new insight into the common mitochondrial response to mtDNA stress and can be implied also on DXR-induced mitochondrial cytotoxicity. - Highlights: • The mechanism for mitochondrial nucleoid clustering is proposed. • DNA intercalators (Doxorubicin or Ethidium Bromide) prevent TFAM binding to mtDNA. • Replicating nucleoids are less prone to DNA intercalator and preserve more TFAM. • Nucleoid clusters mostly contain nucleoids with newly replicated mtDNA. • Recently replicated nucleoids are protected in clusters by increased TFAM and p53.« less
DNA replication-timing analysis of human chromosome 22 at high resolution and different developmental states.

PubMed

White, Eric J; Emanuelsson, Olof; Scalzo, David; Royce, Thomas; Kosak, Steven; Oakeley, Edward J; Weissman, Sherman; Gerstein, Mark; Groudine, Mark; Snyder, Michael; Schübeler, Dirk

2004-12-21

Duplication of the genome during the S phase of the cell cycle does not occur simultaneously; rather, different sequences are replicated at different times. The replication timing of specific sequences can change during development; however, the determinants of this dynamic process are poorly understood. To gain insights into the contribution of developmental state, genomic sequence, and transcriptional activity to replication timing, we investigated the timing of DNA replication at high resolution along an entire human chromosome (chromosome 22) in two different cell types. The pattern of replication timing was correlated with respect to annotated genes, gene expression, novel transcribed regions of unknown function, sequence composition, and cytological features. We observed that chromosome 22 contains regions of early- and late-replicating domains of 100 kb to 2 Mb, many (but not all) of which are associated with previously described chromosomal bands. In both cell types, expressed sequences are replicated earlier than nontranscribed regions. However, several highly transcribed regions replicate late. Overall, the DNA replication-timing profiles of the two different cell types are remarkably similar, with only nine regions of difference observed. In one case, this difference reflects the differential expression of an annotated gene that resides in this region. Novel transcribed regions with low coding potential exhibit a strong propensity for early DNA replication. Although the cellular function of such transcripts is poorly understood, our results suggest that their activity is linked to the replication-timing program.
Tracking neural correlates of successful learning over repeated sequence observations

PubMed Central

Steinemann, Natalie A.; Moisello, Clara; Ghilardi, M. Felice; Kelly, Simon P.

2016-01-01

The neural correlates of memory formation in humans have long been investigated by exposing subjects to diverse material and comparing responses to items later remembered to those forgotten. Tasks requiring memorization of sensory sequences afford unique possibilities for linking neural memorization processes to behavior, because, rather than comparing across different items of varying content, each individual item can be examined across the successive learning states of being initially unknown, newly learned, and eventually, fully known. Sequence learning paradigms have not yet been exploited in this way, however. Here, we analyze the event-related potentials of subjects attempting to memorize sequences of visual locations over several blocks of repeated observation, with respect to pre- and post-block recall tests. Over centro-parietal regions, we observed a rapid P300 component superimposed on a broader positivity, which exhibited distinct modulations across learning states that were replicated in two separate experiments. Consistent with its well-known encoding of surprise, the P300 deflection monotonically decreased over blocks as locations became better learned and hence more expected. In contrast, the broader positivity was especially elevated at the point when a given item was newly learned, i.e., started being successfully recalled. These results implicate the Broad Positivity in endogenously-driven, intentional memory formation, whereas the P300, in processing the current stimulus to the degree that it was previously uncertain, indexes the cumulative knowledge thereby gained. The decreasing surprise/P300 effect significantly predicted learning success both across blocks and across subjects. This presents a new, neural-based means to evaluate learning capabilities independent of verbal reports, which could have considerable value in distinguishing genuine learning disabilities from difficulties to communicate the outcomes of learning, or perceptual impairments, in a range of clinical brain disorders. PMID:27155129
Characterization of a dam Mutant of Serratia marcescens and Nucleotide Sequence of the dam Region

PubMed Central

Ostendorf, Tammo; Cherepanov, Peter; de Vries, Johann; Wackernagel, Wilfried

1999-01-01

The DNA of Serratia marcescens has N6-adenine methylation in GATC sequences. Among 2-aminopurine-sensitive mutants isolated from S. marcescens Sr41, one was identified which lacked GATC methylation. The mutant showed up to 30-fold increased spontaneous mutability and enhanced mutability after treatment with 2-aminopurine, ethyl methanesulfonate, or UV light. The gene (dam) coding for the adenine methyltransferase (Dam enzyme) of S. marcescens was identified on a gene bank plasmid which alleviated the 2-aminopurine sensitivity and the higher mutability of a dam-13::Tn9 mutant of Escherichia coli. Nucleotide sequencing revealed that the deduced amino acid sequence of Dam (270 amino acids; molecular mass, 31.3 kDa) has 72% identity to the Dam enzyme of E. coli. The dam gene is located between flanking genes which are similar to those found to the sides of the E. coli dam gene. The results of complementation studies indicated that like Dam of E. coli and unlike Dam of Vibrio cholerae, the Dam enzyme of S. marcescens plays an important role in mutation avoidance by allowing the mismatch repair enzymes to discriminate between the parental and newly synthesized strands during correction of replication errors. PMID:10383952
Structure and Temporal Dynamics of Populations within Wheat Streak Mosaic Virus Isolates

PubMed Central

Hall, Jeffrey S.; French, Roy; Morris, T. Jack; Stenger, Drake C.

2001-01-01

Variation within the Type and Sidney 81 strains of wheat streak mosaic virus was assessed by single-strand conformation polymorphism (SSCP) analysis and confirmed by nucleotide sequencing. Limiting-dilution subisolates (LDSIs) of each strain were evaluated for polymorphism in the P1, P3, NIa, and CP cistrons. Different SSCP patterns among LDSIs of a strain were associated with single-nucleotide substitutions. Sidney 81 LDSI-S10 was used as founding inoculum to establish three lineages each in wheat, corn, and barley. The P1, HC-Pro, P3, CI, NIa, NIb, and CP cistrons of LDSI-S10 and each lineage at passages 1, 3, 6, and 9 were evaluated for polymorphism. By passage 9, each lineage differed in consensus sequence from LDSI-S10. The majority of substitutions occurred within NIa and CP, although at least one change occurred in each cistron except HC-Pro and P3. Most consensus sequence changes among lineages were independent, with substitutions accumulating over time. However, LDSI-S10 bore a variant nucleotide (G6016) in NIa that was restored to A6016 in eight of nine lineages by passage 6. This near-global reversion is most easily explained by selection. Examination of nonconsensus variation revealed a pool of unique substitutions (singletons) that remained constant in frequency during passage, regardless of the host species examined. These results suggest that mutations arising by viral polymerase error are generated at a constant rate but that most newly generated mutants are sequestered in virions and do not serve as replication templates. Thus, a substantial fraction of variation generated is static and has yet to be tested for relative fitness. In contrast, nonsingleton variation increased upon passage, suggesting that some mutants do serve as replication templates and may become established in a population. Replicated mutants may or may not rise to prominence to become the consensus sequence in a lineage, with the fate of any particular mutant subject to selection and stochastic processes such as genetic drift and population growth factors. PMID:11581391
Within-genome evolution of REPINs: a new family of miniature mobile DNA in bacteria.

PubMed

Bertels, Frederic; Rainey, Paul B

2011-06-01

Repetitive sequences are a conserved feature of many bacterial genomes. While first reported almost thirty years ago, and frequently exploited for genotyping purposes, little is known about their origin, maintenance, or processes affecting the dynamics of within-genome evolution. Here, beginning with analysis of the diversity and abundance of short oligonucleotide sequences in the genome of Pseudomonas fluorescens SBW25, we show that over-represented short sequences define three distinct groups (GI, GII, and GIII) of repetitive extragenic palindromic (REP) sequences. Patterns of REP distribution suggest that closely linked REP sequences form a functional replicative unit: REP doublets are over-represented, randomly distributed in extragenic space, and more highly conserved than singlets. In addition, doublets are organized as inverted repeats, which together with intervening spacer sequences are predicted to form hairpin structures in ssDNA or mRNA. We refer to these newly defined entities as REPINs (REP doublets forming hairpins) and identify short reads from population sequencing that reveal putative transposition intermediates. The proximal relationship between GI, GII, and GIII REPINs and specific REP-associated tyrosine transposases (RAYTs), combined with features of the putative transposition intermediate, suggests a mechanism for within-genome dissemination. Analysis of the distribution of REPs in a range of RAYT-containing bacterial genomes, including Escherichia coli K-12 and Nostoc punctiforme, show that REPINs are a widely distributed, but hitherto unrecognized, family of miniature non-autonomous mobile DNA.
Mammalian DNA enriched for replication origins is enriched for snap-back sequences.

PubMed

Zannis-Hadjopoulos, M; Kaufmann, G; Martin, R G

1984-11-15

Using the instability of replication loops as a method for the isolation of double-stranded nascent DNA, extruded DNA enriched for replication origins was obtained and denatured. Snap-back DNA, single-stranded DNA with inverted repeats (palindromic sequences), reassociates rapidly into stem-loop structures with zero-order kinetics when conditions are changed from denaturing to renaturing, and can be assayed by chromatography on hydroxyapatite. Origin-enriched nascent DNA strands from mouse, rat and monkey cells growing either synchronously or asynchronously were purified and assayed for the presence of snap-back sequences. The results show that origin-enriched DNA is also enriched for snap-back sequences, implying that some origins for mammalian DNA replication contain or lie near palindromic sequences.
The dynamics of genome replication using deep sequencing

PubMed Central

Müller, Carolin A.; Hawkins, Michelle; Retkute, Renata; Malla, Sunir; Wilson, Ray; Blythe, Martin J.; Nakato, Ryuichiro; Komata, Makiko; Shirahige, Katsuhiko; de Moura, Alessandro P.S.; Nieduszynski, Conrad A.

2014-01-01

Eukaryotic genomes are replicated from multiple DNA replication origins. We present complementary deep sequencing approaches to measure origin location and activity in Saccharomyces cerevisiae. Measuring the increase in DNA copy number during a synchronous S-phase allowed the precise determination of genome replication. To map origin locations, replication forks were stalled close to their initiation sites; therefore, copy number enrichment was limited to origins. Replication timing profiles were generated from asynchronous cultures using fluorescence-activated cell sorting. Applying this technique we show that the replication profiles of haploid and diploid cells are indistinguishable, indicating that both cell types use the same cohort of origins with the same activities. Finally, increasing sequencing depth allowed the direct measure of replication dynamics from an exponentially growing culture. This is the first time this approach, called marker frequency analysis, has been successfully applied to a eukaryote. These data provide a high-resolution resource and methodological framework for studying genome biology. PMID:24089142
Adenovirus sequences required for replication in vivo.

PubMed Central

Wang, K; Pearson, G D

1985-01-01

We have studied the in vivo replication properties of plasmids carrying deletion mutations within cloned adenovirus terminal sequences. Deletion mapping located the adenovirus DNA replication origin entirely within the first 67 bp of the adenovirus inverted terminal repeat. This region could be further subdivided into two functional domains: a minimal replication origin and an adjacent auxillary region which boosted the efficiency of replication by more than 100-fold. The minimal origin occupies the first 18 to 21 bp and includes sequences conserved between all adenovirus serotypes. The adjacent auxillary region extends past nucleotide 36 but not past nucleotide 67 and contains the binding site for nuclear factor I. Images PMID:2991857
High-resolution mapping, characterization, and optimization of autonomously replicating sequences in yeast

PubMed Central

Liachko, Ivan; Youngblood, Rachel A.; Keich, Uri; Dunham, Maitreya J.

2013-01-01

DNA replication origins are necessary for the duplication of genomes. In addition, plasmid-based expression systems require DNA replication origins to maintain plasmids efficiently. The yeast autonomously replicating sequence (ARS) assay has been a valuable tool in dissecting replication origin structure and function. However, the dearth of information on origins in diverse yeasts limits the availability of efficient replication origin modules to only a handful of species and restricts our understanding of origin function and evolution. To enable rapid study of origins, we have developed a sequencing-based suite of methods for comprehensively mapping and characterizing ARSs within a yeast genome. Our approach finely maps genomic inserts capable of supporting plasmid replication and uses massively parallel deep mutational scanning to define molecular determinants of ARS function with single-nucleotide resolution. In addition to providing unprecedented detail into origin structure, our data have allowed us to design short, synthetic DNA sequences that retain maximal ARS function. These methods can be readily applied to understand and modulate ARS function in diverse systems. PMID:23241746
Nuclear Mitochondrial DNA Activates Replication in Saccharomyces cerevisiae

PubMed Central

Chatre, Laurent; Ricchetti, Miria

2011-01-01

The nuclear genome of eukaryotes is colonized by DNA fragments of mitochondrial origin, called NUMTs. These insertions have been associated with a variety of germ-line diseases in humans. The significance of this uptake of potentially dangerous sequences into the nuclear genome is unclear. Here we provide functional evidence that sequences of mitochondrial origin promote nuclear DNA replication in Saccharomyces cerevisiae. We show that NUMTs are rich in key autonomously replicating sequence (ARS) consensus motifs, whose mutation results in the reduction or loss of DNA replication activity. Furthermore, 2D-gel analysis of the mrc1 mutant exposed to hydroxyurea shows that several NUMTs function as late chromosomal origins. We also show that NUMTs located close to or within ARS provide key sequence elements for replication. Thus NUMTs can act as independent origins, when inserted in an appropriate genomic context or affect the efficiency of pre-existing origins. These findings show that migratory mitochondrial DNAs can impact on the replication of the nuclear region they are inserted in. PMID:21408151
Nuclear mitochondrial DNA activates replication in Saccharomyces cerevisiae.

PubMed

Chatre, Laurent; Ricchetti, Miria

2011-03-08

The nuclear genome of eukaryotes is colonized by DNA fragments of mitochondrial origin, called NUMTs. These insertions have been associated with a variety of germ-line diseases in humans. The significance of this uptake of potentially dangerous sequences into the nuclear genome is unclear. Here we provide functional evidence that sequences of mitochondrial origin promote nuclear DNA replication in Saccharomyces cerevisiae. We show that NUMTs are rich in key autonomously replicating sequence (ARS) consensus motifs, whose mutation results in the reduction or loss of DNA replication activity. Furthermore, 2D-gel analysis of the mrc1 mutant exposed to hydroxyurea shows that several NUMTs function as late chromosomal origins. We also show that NUMTs located close to or within ARS provide key sequence elements for replication. Thus NUMTs can act as independent origins, when inserted in an appropriate genomic context or affect the efficiency of pre-existing origins. These findings show that migratory mitochondrial DNAs can impact on the replication of the nuclear region they are inserted in.

Within-Genome Evolution of REPINs: a New Family of Miniature Mobile DNA in Bacteria

PubMed Central

Bertels, Frederic; Rainey, Paul B.

2011-01-01

Repetitive sequences are a conserved feature of many bacterial genomes. While first reported almost thirty years ago, and frequently exploited for genotyping purposes, little is known about their origin, maintenance, or processes affecting the dynamics of within-genome evolution. Here, beginning with analysis of the diversity and abundance of short oligonucleotide sequences in the genome of Pseudomonas fluorescens SBW25, we show that over-represented short sequences define three distinct groups (GI, GII, and GIII) of repetitive extragenic palindromic (REP) sequences. Patterns of REP distribution suggest that closely linked REP sequences form a functional replicative unit: REP doublets are over-represented, randomly distributed in extragenic space, and more highly conserved than singlets. In addition, doublets are organized as inverted repeats, which together with intervening spacer sequences are predicted to form hairpin structures in ssDNA or mRNA. We refer to these newly defined entities as REPINs (REP doublets forming hairpins) and identify short reads from population sequencing that reveal putative transposition intermediates. The proximal relationship between GI, GII, and GIII REPINs and specific REP-associated tyrosine transposases (RAYTs), combined with features of the putative transposition intermediate, suggests a mechanism for within-genome dissemination. Analysis of the distribution of REPs in a range of RAYT–containing bacterial genomes, including Escherichia coli K-12 and Nostoc punctiforme, show that REPINs are a widely distributed, but hitherto unrecognized, family of miniature non-autonomous mobile DNA. PMID:21698139
Best practices for mapping replication origins in eukaryotic chromosomes.

PubMed

Besnard, Emilie; Desprat, Romain; Ryan, Michael; Kahli, Malik; Aladjem, Mirit I; Lemaitre, Jean-Marc

2014-09-02

Understanding the regulatory principles ensuring complete DNA replication in each cell division is critical for deciphering the mechanisms that maintain genomic stability. Recent advances in genome sequencing technology facilitated complete mapping of DNA replication sites and helped move the field from observing replication patterns at a handful of single loci to analyzing replication patterns genome-wide. These advances address issues, such as the relationship between replication initiation events, transcription, and chromatin modifications, and identify potential replication origin consensus sequences. This unit summarizes the technological and fundamental aspects of replication profiling and briefly discusses novel insights emerging from mining large datasets, published in the last 3 years, and also describes DNA replication dynamics on a whole-genome scale. Copyright © 2014 John Wiley & Sons, Inc.
Investigation of a Canine Parvovirus Outbreak using Next Generation Sequencing.

PubMed

Parker, Jayme; Murphy, Molly; Hueffer, Karsten; Chen, Jack

2017-08-29

Canine parvovirus (CPV) outbreaks can have a devastating effect in communities with dense dog populations. The interior region of Alaska experienced a CPV outbreak in the winter of 2016 leading to the further investigation of the virus due to reports of increased morbidity and mortality occurring at dog mushing kennels in the area. Twelve rectal-swab specimens from dogs displaying clinical signs consistent with parvoviral-associated disease were processed using next-generation sequencing (NGS) methodologies by targeting RNA transcripts, and therefore detecting only replicating virus. All twelve specimens demonstrated the presence of the CPV transcriptome, with read depths ranging from 2.2X - 12,381X, genome coverage ranging from 44.8-96.5%, and representation of CPV sequencing reads to those of the metagenome background ranging from 0.0015-6.7%. Using the data generated by NGS, the presence of newly evolved, yet known, strains of both CPV-2a and CPV-2b were identified and grouped geographically. Deep-sequencing data provided additional diagnostic information in terms of investigating novel CPV in this outbreak. NGS data in addition to limited serological data provided strong diagnostic evidence that this outbreak most likely arose from unvaccinated or under-vaccinated canines, not from a novel CPV strain incapable of being neutralized by current vaccination efforts.
Discovery of three novel coccidian parasites infecting California sea lions (Zalophus californianus), with evidence of sexual replication and interspecies pathogenicity.

PubMed

Colegrove, Kathleen M; Grigg, Michael E; Carlson-Bremer, Daphne; Miller, Robin H; Gulland, Frances M D; Ferguson, David J P; Rejmanek, Daniel; Barr, Bradd C; Nordhausen, Robert; Melli, Ann C; Conrad, Patricia A

2011-10-01

Enteric protozoal infection was identified in 5 stranded California sea lions (Zalophus californianus). Microscopically, the apical cytoplasm of distal jejunal enterocytes contained multiple stages of coccidian parasites, including schizonts with merozoites and spherical gametocytes, which were morphologically similar to coccidians. By histopathology, organisms appeared to be confined to the intestine and accompanied by only mild enteritis. Using electron microscopy, both sexual (microgametocytes, macrogamonts) and asexual (schizonts, merozoites) coccidian stages were identified in enterocytes within parasitophorous vacuoles, consistent with apicomplexan development in a definitive host. Serology was negative for tissue cyst-forming coccidians, and immunohistochemistry for Toxoplasma gondii was inconclusive and negative for Neospora caninum and Sarcocystis neurona. Analysis of ITS-1 gene sequences amplified from frozen or formalin-fixed paraffin-embedded intestinal sections identified DNA sequences with closest homology to Neospora sp. (80%); these novel sequences were referred to as belonging to coccidian parasites "A," "B," and "C." Subsequent molecular analyses completed on a neonatal harbor seal (Phoca vitulina) with protozoal lymphadenitis, hepatitis, myocarditis, and encephalitis showed that it was infected with a coccidian parasite bearing the "C" sequence type. Our results indicate that sea lions likely serve as definitive hosts for 3 newly described coccidian parasites, at least 1 of which is pathogenic in a marine mammal intermediate host species.
Non coding extremities of the seven influenza virus type C vRNA segments: effect on transcription and replication by the type C and type A polymerase complexes

PubMed Central

Crescenzo-Chaigne, Bernadette; Barbezange, Cyril; van der Werf, Sylvie

2008-01-01

Background The transcription/replication of the influenza viruses implicate the terminal nucleotide sequences of viral RNA, which comprise sequences at the extremities conserved among the genomic segments as well as variable 3' and 5' non-coding (NC) regions. The plasmid-based system for the in vivo reconstitution of functional ribonucleoproteins, upon expression of viral-like RNAs together with the nucleoprotein and polymerase proteins has been widely used to analyze transcription/replication of influenza viruses. It was thus shown that the type A polymerase could transcribe and replicate type A, B, or C vRNA templates whereas neither type B nor type C polymerases were able to transcribe and replicate type A templates efficiently. Here we studied the importance of the NC regions from the seven segments of type C influenza virus for efficient transcription/replication by the type A and C polymerases. Results The NC sequences of the seven genomic segments of the type C influenza virus C/Johannesburg/1/66 strain were found to be more variable in length than those of the type A and B viruses. The levels of transcription/replication of viral-like vRNAs harboring the NC sequences of the respective type C virus segments flanking the CAT reporter gene were comparable in the presence of either type C or type A polymerase complexes except for the NS and PB2-like vRNAs. For the NS-like vRNA, the transcription/replication level was higher after introduction of a U residue at position 6 in the 5' NC region as for all other segments. For the PB2-like vRNA the CAT expression level was particularly reduced with the type C polymerase. Analysis of mutants of the 5' NC sequence in the PB2-like vRNA, the shortest 5' NC sequence among the seven segments, showed that additional sequences within the PB2 ORF were essential for the efficiency of transcription but not replication by the type C polymerase complex. Conclusion In the context of a PB2-like reporter vRNA template, the sequence upstream the polyU stretch plays a role in the transcription/replication process by the type C polymerase complex. PMID:18973655
Characterization of host-dependent mutations of apple fruit crinkle viroid replicating in newly identified experimental hosts suggests maintenance of stem-loop structures in the left-hand half of the molecule is important for replication.

PubMed

Suzuki, Takahiro; Fujibayashi, Misato; Hataya, Tatsuji; Taneda, Akito; He, Ying-Hong; Tsushima, Taro; Duraisamy, Ganesh Selvaraj; Siglová, Kristyna; Matoušek, Jaroslav; Sano, Teruo

2017-03-01

Apple fruit crinkle viroid (AFCVd) is a tentative member of the genus Apscaviroid, family Pospiviroidae. AFCVd has a narrow host range and is known to infect apple, hop and persimmon as natural hosts. In this study, tomato, cucumber and wild hop have been identified as new experimental herbaceous hosts. Foliar symptoms were very mild or virtually undetectable, but fruits of infected tomato were small, cracked and distorted. These symptoms resemble those observed on some AFCVd-sensitive apple cultivars. After transfer to tomato, cucumber and wild hop, sequence changes were detected in a natural AFCVd isolate from hop, and major variants in tomato, cucumber and wild hop differed in 10, 8 or 2 nucleotides, respectively, from the predominant one in the inoculum. The major variants in tomato and cucumber were almost identical, and the one in wild hop was very similar to the one in cultivated hop. Detailed analyses of the host-dependent sequence changes that appear in a naturally occurring AFCVd isolate from hop after transfer to tomato using small RNA deep sequence data and infectivity studies with dimeric RNA transcripts followed by progeny analysis indicate that the major AFCVd variant in tomato emerged by selection of a minor variant present in the inoculum (i.e. hop) followed by one to two host-dependent de novo mutations. Comparison of the secondary structures of major variants in hop, tomato and persimmon after transfer to tomato suggested that maintenance of stem-loop structures in the left-hand half of the molecule is critical for infection.
Strong minor groove base conservation in sequence logos implies DNA distortion or base flipping during replication and transcription initiation.

PubMed

Schneider, T D

2001-12-01

The sequence logo for DNA binding sites of the bacteriophage P1 replication protein RepA shows unusually high sequence conservation ( approximately 2 bits) at a minor groove that faces RepA. However, B-form DNA can support only 1 bit of sequence conservation via contacts into the minor groove. The high conservation in RepA sites therefore implies a distorted DNA helix with direct or indirect contacts to the protein. Here I show that a high minor groove conservation signature also appears in sequence logos of sites for other replication origin binding proteins (Rts1, DnaA, P4 alpha, EBNA1, ORC) and promoter binding proteins (sigma(70), sigma(D) factors). This finding implies that DNA binding proteins generally use non-B-form DNA distortion such as base flipping to initiate replication and transcription.
Ribosomal DNA replication fork barrier and HOT1 recombination hot spot: shared sequences but independent activities.

PubMed

Ward, T R; Hoang, M L; Prusty, R; Lau, C K; Keil, R L; Fangman, W L; Brewer, B J

2000-07-01

In the ribosomal DNA of Saccharomyces cerevisiae, sequences in the nontranscribed spacer 3' of the 35S ribosomal RNA gene are important to the polar arrest of replication forks at a site called the replication fork barrier (RFB) and also to the cis-acting, mitotic hyperrecombination site called HOT1. We have found that the RFB and HOT1 activity share some but not all of their essential sequences. Many of the mutations that reduce HOT1 recombination also decrease or eliminate fork arrest at one of two closely spaced RFB sites, RFB1 and RFB2. A simple model for the juxtaposition of RFB and HOT1 sequences is that the breakage of strands in replication forks arrested at RFB stimulates recombination. Contrary to this model, we show here that HOT1-stimulated recombination does not require the arrest of forks at the RFB. Therefore, while HOT1 activity is independent of replication fork arrest, HOT1 and RFB require some common sequences, suggesting the existence of a common trans-acting factor(s).
Context based computational analysis and characterization of ARS consensus sequences (ACS) of Saccharomyces cerevisiae genome.

PubMed

Singh, Vinod Kumar; Krishnamachari, Annangarachari

2016-09-01

Genome-wide experimental studies in Saccharomyces cerevisiae reveal that autonomous replicating sequence (ARS) requires an essential consensus sequence (ACS) for replication activity. Computational studies identified thousands of ACS like patterns in the genome. However, only a few hundreds of these sites act as replicating sites and the rest are considered as dormant or evolving sites. In a bid to understand the sequence makeup of replication sites, a content and context-based analysis was performed on a set of replicating ACS sequences that binds to origin-recognition complex (ORC) denoted as ORC-ACS and non-replicating ACS sequences (nrACS), that are not bound by ORC. In this study, DNA properties such as base composition, correlation, sequence dependent thermodynamic and DNA structural profiles, and their positions have been considered for characterizing ORC-ACS and nrACS. Analysis reveals that ORC-ACS depict marked differences in nucleotide composition and context features in its vicinity compared to nrACS. Interestingly, an A-rich motif was also discovered in ORC-ACS sequences within its nucleosome-free region. Profound changes in the conformational features, such as DNA helical twist, inclination angle and stacking energy between ORC-ACS and nrACS were observed. Distribution of ACS motifs in the non-coding segments points to the locations of ORC-ACS which are found far away from the adjacent gene start position compared to nrACS thereby enabling an accessible environment for ORC-proteins. Our attempt is novel in considering the contextual view of ACS and its flanking region along with nucleosome positioning in the S. cerevisiae genome and may be useful for any computational prediction scheme.
Gause's Principle and the Effect of Resource Partitioning on the Dynamical Coexistence of Replicating Templates

PubMed Central

Szilágyi, András; Zachar, István; Szathmáry, Eörs

2013-01-01

Models of competitive template replication, although basic for replicator dynamics and primordial evolution, have not yet taken different sequences explicitly into account, neither have they analyzed the effect of resource partitioning (feeding on different resources) on coexistence. Here we show by analytical and numerical calculations that Gause's principle of competitive exclusion holds for template replicators if resources (nucleotides) affect growth linearly and coexistence is at fixed point attractors. Cases of complementary or homologous pairing between building blocks with parallel or antiparallel strands show no deviation from the rule that the nucleotide compositions of stably coexisting species must be different and there cannot be more coexisting replicator species than nucleotide types. Besides this overlooked mechanism of template coexistence we show also that interesting sequence effects prevail as parts of sequences that are copied earlier affect coexistence more strongly due to the higher concentration of the corresponding replication intermediates. Template and copy always count as one species due their constraint of strict stoichiometric coupling. Stability of fixed-point coexistence tends to decrease with the length of sequences, although this effect is unlikely to be detrimental for sequences below 100 nucleotides. In sum, resource partitioning (niche differentiation) is the default form of competitive coexistence for replicating templates feeding on a cocktail of different nucleotides, as it may have been the case in the RNA world. Our analysis of different pairing and strand orientation schemes is relevant for artificial and potentially astrobiological genetics. PMID:23990769
An epigenetic state associated with areas of gene duplication

PubMed Central

Gimelbrant, Alexander A.; Chess, Andrew

2006-01-01

Asynchronous DNA replication is an epigenetically determined feature found in all cases of monoallelic expression, including genomic imprinting, X-inactivation, and random monoallelic expression of autosomal genes such as immunoglobulins and olfactory receptor genes. Most genes of the latter class were identified in experiments focused on genes functioning in the chemosensory and immune systems. We performed an unbiased survey of asynchronous replication in the mouse genome, excluding known asynchronously replicated genes. Fully 10% (eight of 80) of the genes tested exhibited asynchronous replication. A common feature of the newly identified asynchronously replicated areas is their proximity to areas of tandem gene duplication. Testing of other clustered areas supported the idea that such regions are enriched with asynchronously replicated genes. PMID:16687731
Enzyme-Free Replication with Two or Four Bases.

PubMed

Richert, Clemens; Hänle, Elena

2018-05-20

All known forms of life encode their genetic information in a sequence of bases of a genetic polymer and produce copies of their genes via semiconservative replication. How this process started before polymerase enzymes had been evolved is unclear. Enzyme-free copying of short stretches of DNA or RNA sequence has been demonstrated, using activated nucleotides, but not replication. We have developed a methodology for replication. It involves extension with reversible termination, enzyme-free ligation, and strand capture and allowed us to monitor nucleotide incorporation for an entire helical turn of DNA, both during a first and a second round of copying. When tracking replication mass spectrometrically, we found that with all four bases (A/C/G/T) an 'error catastrophe' occurs, with the correct sequence being 'overwhelmed' by incorrect ones. When only C and G were used, approx. half of all daughter strands had the mass of the correct sequence after 20 nonenzymatic copying steps. We conclude that enzyme-free replication is more likely to be successful with the two strongly pairing bases, rather than all four bases of the genetic alphabet. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Scoring schemes of palindrome clusters for more sensitive prediction of replication origins in herpesviruses

PubMed Central

Chew, David S. H.; Choi, Kwok Pui; Leung, Ming-Ying

2005-01-01

Many empirical studies show that there are unusual clusters of palindromes, closely spaced direct and inverted repeats around the replication origins of herpesviruses. In this paper, we introduce two new scoring schemes to quantify the spatial abundance of palindromes in a genomic sequence. Based on these scoring schemes, a computational method to predict the locations of replication origins is developed. When our predictions are compared with 39 known or annotated replication origins in 19 herpesviruses, close to 80% of the replication origins are located within 2% of the genome length. A list of predicted locations of replication origins in all the known herpesviruses with complete genome sequences is reported. PMID:16141192
Novel features of ARS selection in budding yeast Lachancea kluyveri

PubMed Central

2011-01-01

Background The characterization of DNA replication origins in yeast has shed much light on the mechanisms of initiation of DNA replication. However, very little is known about the evolution of origins or the evolution of mechanisms through which origins are recognized by the initiation machinery. This lack of understanding is largely due to the vast evolutionary distances between model organisms in which origins have been examined. Results In this study we have isolated and characterized autonomously replicating sequences (ARSs) in Lachancea kluyveri - a pre-whole genome duplication (WGD) budding yeast. Through a combination of experimental work and rigorous computational analysis, we show that L. kluyveri ARSs require a sequence that is similar but much longer than the ARS Consensus Sequence well defined in Saccharomyces cerevisiae. Moreover, compared with S. cerevisiae and K. lactis, the replication licensing machinery in L. kluyveri seems more tolerant to variations in the ARS sequence composition. It is able to initiate replication from almost all S. cerevisiae ARSs tested and most Kluyveromyces lactis ARSs. In contrast, only about half of the L. kluyveri ARSs function in S. cerevisiae and less than 10% function in K. lactis. Conclusions Our findings demonstrate a replication initiation system with novel features and underscore the functional diversity within the budding yeasts. Furthermore, we have developed new approaches for analyzing biologically functional DNA sequences with ill-defined motifs. PMID:22204614
Novel features of ARS selection in budding yeast Lachancea kluyveri.

PubMed

Liachko, Ivan; Tanaka, Emi; Cox, Katherine; Chung, Shau Chee Claire; Yang, Lu; Seher, Arael; Hallas, Lindsay; Cha, Eugene; Kang, Gina; Pace, Heather; Barrow, Jasmine; Inada, Maki; Tye, Bik-Kwoon; Keich, Uri

2011-12-28

The characterization of DNA replication origins in yeast has shed much light on the mechanisms of initiation of DNA replication. However, very little is known about the evolution of origins or the evolution of mechanisms through which origins are recognized by the initiation machinery. This lack of understanding is largely due to the vast evolutionary distances between model organisms in which origins have been examined. In this study we have isolated and characterized autonomously replicating sequences (ARSs) in Lachancea kluyveri - a pre-whole genome duplication (WGD) budding yeast. Through a combination of experimental work and rigorous computational analysis, we show that L. kluyveri ARSs require a sequence that is similar but much longer than the ARS Consensus Sequence well defined in Saccharomyces cerevisiae. Moreover, compared with S. cerevisiae and K. lactis, the replication licensing machinery in L. kluyveri seems more tolerant to variations in the ARS sequence composition. It is able to initiate replication from almost all S. cerevisiae ARSs tested and most Kluyveromyces lactis ARSs. In contrast, only about half of the L. kluyveri ARSs function in S. cerevisiae and less than 10% function in K. lactis. Our findings demonstrate a replication initiation system with novel features and underscore the functional diversity within the budding yeasts. Furthermore, we have developed new approaches for analyzing biologically functional DNA sequences with ill-defined motifs.
Identification and molecular characterization of a novel circular single-stranded DNA virus associated with yerba mate in Argentina.

PubMed

Bejerman, Nicolás; de Breuil, Soledad; Nome, Claudia

2018-06-06

A single-stranded DNA (ssDNA) virus was detected in Yerba mate samples showing chlorotic linear patterns, chlorotic rings and vein yellowing. The full-genome sequences of six different isolates of this ssDNA circular virus were obtained, which share > 99% sequence identity with each other. The newly identified virus has been tentatively named as yerba mate-associated circular DNA virus (YMaCV). The 2707 nt-long viral genome has two and three open reading frame on its complementary and virion-sense strands, respectively. The coat protein is more similar to that of mastreviruses (44% identity), whereas the replication-associated protein of YMaCV is more similar (49% identity) to that encoded by a recently described, unclassified ssDNA virus isolated on trees in Brazil. This is the first report of a circular DNA virus associated with yerba mate. Its unique genome organization and phylogenetic relationships indicates that YMaCV represents a distinct evolutionary lineage within the ssDNA viruses and therefore this virus should be classified as a member of a new species within an unassigned genus or family.
Initiation preference at a yeast origin of replication.

PubMed

Brewer, B J; Fangman, W L

1994-04-12

Replication origins in the yeast Saccharomyces cerevisiae are identified as autonomous replication sequence (ARS) elements. To examine the effect of origin density on replication initiation, we have analyzed the replication of a plasmid that contains two copies of the same origin, ARS1. The activation of origins and the direction that replication forks move through flanking sequences can be physically determined by analyzing replication intermediates on two-dimensional agarose gels. We find that only one of the two identical ARSs on the plasmid initiates replication on any given plasmid molecule; that is, this close spacing of ARSs results in an apparent interference between the potential origins. Moreover, in the particular plasmid that we constructed, one of the two identical copies of ARS1 is used four times more frequently than the other one. These results show that the plasmid context is critical for determining the preferred origin. This origin preference is also exhibited when the tandem copies of ARS1 are introduced into a yeast chromosome. The sequences responsible for establishing the origin preference have been identified by deletion analysis and are found to reside in a portion of the yeast URA3 gene.
Mapping vaccinia virus DNA replication origins at nucleotide level by deep sequencing.

PubMed

Senkevich, Tatiana G; Bruno, Daniel; Martens, Craig; Porcella, Stephen F; Wolf, Yuri I; Moss, Bernard

2015-09-01

Poxviruses reproduce in the host cytoplasm and encode most or all of the enzymes and factors needed for expression and synthesis of their double-stranded DNA genomes. Nevertheless, the mode of poxvirus DNA replication and the nature and location of the replication origins remain unknown. A current but unsubstantiated model posits only leading strand synthesis starting at a nick near one covalently closed end of the genome and continuing around the other end to generate a concatemer that is subsequently resolved into unit genomes. The existence of specific origins has been questioned because any plasmid can replicate in cells infected by vaccinia virus (VACV), the prototype poxvirus. We applied directional deep sequencing of short single-stranded DNA fragments enriched for RNA-primed nascent strands isolated from the cytoplasm of VACV-infected cells to pinpoint replication origins. The origins were identified as the switching points of the fragment directions, which correspond to the transition from continuous to discontinuous DNA synthesis. Origins containing a prominent initiation point mapped to a sequence within the hairpin loop at one end of the VACV genome and to the same sequence within the concatemeric junction of replication intermediates. These findings support a model for poxvirus genome replication that involves leading and lagging strand synthesis and is consistent with the requirements for primase and ligase activities as well as earlier electron microscopic and biochemical studies implicating a replication origin at the end of the VACV genome.
Genome-Wide Analysis of the Arabidopsis Replication Timing Program1[OPEN

PubMed Central

Brooks, Ashley M.; Wheeler, Emily; LeBlanc, Chantal; Lee, Tae-Jin; Martienssen, Robert A.; Thompson, William F.

2018-01-01

Eukaryotes use a temporally regulated process, known as the replication timing program, to ensure that their genomes are fully and accurately duplicated during S phase. Replication timing programs are predictive of genomic features and activity and are considered to be functional readouts of chromatin organization. Although replication timing programs have been described for yeast and animal systems, much less is known about the temporal regulation of plant DNA replication or its relationship to genome sequence and chromatin structure. We used the thymidine analog, 5-ethynyl-2′-deoxyuridine, in combination with flow sorting and Repli-Seq to describe, at high-resolution, the genome-wide replication timing program for Arabidopsis (Arabidopsis thaliana) Col-0 suspension cells. We identified genomic regions that replicate predominantly during early, mid, and late S phase, and correlated these regions with genomic features and with data for chromatin state, accessibility, and long-distance interaction. Arabidopsis chromosome arms tend to replicate early while pericentromeric regions replicate late. Early and mid-replicating regions are gene-rich and predominantly euchromatic, while late regions are rich in transposable elements and primarily heterochromatic. However, the distribution of chromatin states across the different times is complex, with each replication time corresponding to a mixture of states. Early and mid-replicating sequences interact with each other and not with late sequences, but early regions are more accessible than mid regions. The replication timing program in Arabidopsis reflects a bipartite genomic organization with early/mid-replicating regions and late regions forming separate, noninteracting compartments. The temporal order of DNA replication within the early/mid compartment may be modulated largely by chromatin accessibility. PMID:29301956
Affordable in-house antiretroviral drug resistance assay with good performance in non-subtype B HIV-1

PubMed Central

Wallis, Carole L.; Papathanasopoulos, Maria A.; Lakhi, Shabir; Karita, Etienne; Kamali, Anatoli; Kaleebu, Pontiano; Sanders, Eduard; Anzala, Omu; Bekker, Linda-Gail; Stevens, Gwynn; Rinke de Wit, Tobias F.; Stevens, Wendy

2010-01-01

The introduction of antiretroviral therapy in resource-poor settings is effective in suppressing HIV-1 replication and prolonging life of infected individuals. This has led to a demand for affordable HIV-1 drug resistance assays, since treatment failure due to development of drug resistance is common. This study developed and evaluated an affordable “in–house” genotyping assay to monitor HIV-1 drug resistance in Africa, particularly South Africa. An “in-house” assay using automated RNA extraction, and subtype C specific PCR and sequencing primers was developed and successfully evaluated 396 patient samples (viral load ranges 1,000->1.6million RNA copies/ml). The “in-house” assay was validated by comparing sequence data and drug resistance profiles from 90 patient and 10 external quality control samples to data from the ViroSeqTM HIV-1 Genotyping kit. The “in-house” assay was more efficient, amplifying all 100 samples, compared to 91 samples using Viroseq. The “in house” sequences were 99.2%) homologous to the ViroSeq sequences, and identical drug resistance mutation profiles were observed in 96 samples. Furthermore, the “in-house” assay genotyped 260 of 295 samples from seven African sites, where 47% were non-subtype C. Overall, the newly validated “in-house” drug resistance assay is suited for use in Africa as it overcomes the obstacle of subtype diversity. PMID:19917318

Affordable in-house antiretroviral drug resistance assay with good performance in non-subtype B HIV-1.

PubMed

Wallis, Carole L; Papathanasopoulos, Maria A; Lakhi, Shabir; Karita, Etienne; Kamali, Anatoli; Kaleebu, Pontiano; Sanders, Eduard; Anzala, Omu; Bekker, Linda-Gail; Stevens, Gwynn; de Wit, Tobias F Rinke; Stevens, Wendy

2010-02-01

The introduction of antiretroviral (ARV) therapy in resource-poor settings is effective in suppressing HIV-1 replication and prolonging life of infected individuals. This has led to a demand for affordable HIV-1 drug resistance assays, since treatment failure due to development of drug resistance is common. This study developed and evaluated an affordable "in-house" genotyping assay to monitor HIV-1 drug resistance in Africa, particularly South Africa. An "in-house" assay using automated RNA extraction, and subtype C specific PCR and sequencing primers was developed and successfully evaluated 396 patient samples (viral load ranges 1000-1.6 million RNA copies/ml). The "in-house" assay was validated by comparing sequence data and drug resistance profiles from 90 patient and 10 external quality control samples to data from the ViroSeq HIV-1 Genotyping kit. The "in-house" assay was more efficient, amplifying all 100 samples, compared to 91 samples using Viroseq. The "in house" sequences were 99.2% homologous to the ViroSeq sequences, and identical drug resistance mutation profiles were observed in 96 samples. Furthermore, the "in-house" assay genotyped 260 of 295 samples from seven African sites, where 47% were non-subtype C. Overall, the newly validated "in-house" drug resistance assay is suited for use in Africa as it overcomes the obstacle of subtype diversity. 2009 Elsevier B.V. All rights reserved.
Physics models of centriole replication.

PubMed

Cheng, Kang; Zou, Changhua

2006-01-01

Our previous pre-clinic experimental results have showed that the epithelialization can be enhanced by the externally applied rectangular pulsed electrical current stimulation (RPECS). The results are clinically significant for patients, especially for those difficult patients whose skin wounds need long periods to heal. However, the results also raise questions: How does the RPECS accelerate the epithelium cell proliferation? To answer these questions, we have previously developed several models for animal cells, in a view of physics, to explain mechanisms of mitosis and cytokinesis at a cellular level, and separation of nucleotide sequences and the unwinding of a double helix during DNA replication at a bio-molecular level. In this paper, we further model the mechanism of centriole replication during a natural and normal mitosis and cytokinesis to explore the mechanism of epithelialization enhanced with the externally applied RPECS at a bio-molecular level. Our models suggest: (1) Centriole replication is an information flowing. The direction of the information flowing is from centrioles to centrioles based on a cylindrical template of 9 x 3 protein microtubules (MTs) pattern. (2) A spontaneous and strong electromagnetic field (EMF) force is a pushing force that separates a mother and a daughter centrioles in centrosomes or in cells, while a pulling force of interacting fibers and pericentriolar materials delivers new babies. The newly born babies inherit the pattern information from their mother(s) and grow using microtubule fragments that come through the centrosome pores. A daughter centriole is always born and grows along stronger EMF. The EMF mostly determines centrioles positions and plays key role in centriole replication. We also hypothesize that the normal centriole replication could not been disturbed in centrosome in the epithelium cells by our RPECS, because the centrioles have two non-conducting envelope (cell and centrosome membranes), that protect the normal duplication. The induced electric field by externally applied RPECS could be mild compared with the spontaneous and natural electric field of the centrioles. Therefore, the centriole replication during the epithelium cellular proliferation may be directly, as well as indirectly (e.g., somatic reflex) accelerated by the RPECS.
Identifying sites of replication initiation in yeast chromosomes: looking for origins in all the right places.

PubMed

van Brabant, A J; Hunt, S Y; Fangman, W L; Brewer, B J

1998-06-01

DNA fragments that contain an active origin of replication generate bubble-shaped replication intermediates with diverging forks. We describe two methods that use two-dimensional (2-D) agarose gel electrophoresis along with DNA sequence information to identify replication origins in natural and artificial Saccharomyces cerevisiae chromosomes. The first method uses 2-D gels of overlapping DNA fragments to locate an active chromosomal replication origin within a region known to confer autonomous replication on a plasmid. A variant form of 2-D gels can be used to determine the direction of fork movement, and the second method uses this technique to find restriction fragments that are replicated by diverging forks, indicating that a bidirectional replication origin is located between the two fragments. Either of these two methods can be applied to the analysis of any genomic region for which there is DNA sequence information or an adequate restriction map.
Reproducibility and quantitation of amplicon sequencing-based detection

PubMed Central

Zhou, Jizhong; Wu, Liyou; Deng, Ye; Zhi, Xiaoyang; Jiang, Yi-Huei; Tu, Qichao; Xie, Jianping; Van Nostrand, Joy D; He, Zhili; Yang, Yunfeng

2011-01-01

To determine the reproducibility and quantitation of the amplicon sequencing-based detection approach for analyzing microbial community structure, a total of 24 microbial communities from a long-term global change experimental site were examined. Genomic DNA obtained from each community was used to amplify 16S rRNA genes with two or three barcode tags as technical replicates in the presence of a small quantity (0.1% wt/wt) of genomic DNA from Shewanella oneidensis MR-1 as the control. The technical reproducibility of the amplicon sequencing-based detection approach is quite low, with an average operational taxonomic unit (OTU) overlap of 17.2%±2.3% between two technical replicates, and 8.2%±2.3% among three technical replicates, which is most likely due to problems associated with random sampling processes. Such variations in technical replicates could have substantial effects on estimating β-diversity but less on α-diversity. A high variation was also observed in the control across different samples (for example, 66.7-fold for the forward primer), suggesting that the amplicon sequencing-based detection approach could not be quantitative. In addition, various strategies were examined to improve the comparability of amplicon sequencing data, such as increasing biological replicates, and removing singleton sequences and less-representative OTUs across biological replicates. Finally, as expected, various statistical analyses with preprocessed experimental data revealed clear differences in the composition and structure of microbial communities between warming and non-warming, or between clipping and non-clipping. Taken together, these results suggest that amplicon sequencing-based detection is useful in analyzing microbial community structure even though it is not reproducible and quantitative. However, great caution should be taken in experimental design and data interpretation when the amplicon sequencing-based detection approach is used for quantitative analysis of the β-diversity of microbial communities. PMID:21346791
Iterated function systems for DNA replication

NASA Astrophysics Data System (ADS)

Gaspard, Pierre

2017-10-01

The kinetic equations of DNA replication are shown to be exactly solved in terms of iterated function systems, running along the template sequence and giving the statistical properties of the copy sequences, as well as the kinetic and thermodynamic properties of the replication process. With this method, different effects due to sequence heterogeneity can be studied, in particular, a transition between linear and sublinear growths in time of the copies, and a transition between continuous and fractal distributions of the local velocities of the DNA polymerase along the template. The method is applied to the human mitochondrial DNA polymerase γ without and with exonuclease proofreading.
DNA sequence templates adjacent nucleosome and ORC sites at gene amplification origins in Drosophila

PubMed Central

Liu, Jun; Zimmer, Kurt; Rusch, Douglas B.; Paranjape, Neha; Podicheti, Ram; Tang, Haixu; Calvi, Brian R.

2015-01-01

Eukaryotic origins of DNA replication are bound by the origin recognition complex (ORC), which scaffolds assembly of a pre-replicative complex (pre-RC) that is then activated to initiate replication. Both pre-RC assembly and activation are strongly influenced by developmental changes to the epigenome, but molecular mechanisms remain incompletely defined. We have been examining the activation of origins responsible for developmental gene amplification in Drosophila. At a specific time in oogenesis, somatic follicle cells transition from genomic replication to a locus-specific replication from six amplicon origins. Previous evidence indicated that these amplicon origins are activated by nucleosome acetylation, but how this affects origin chromatin is unknown. Here, we examine nucleosome position in follicle cells using micrococcal nuclease digestion with Ilumina sequencing. The results indicate that ORC binding sites and other essential origin sequences are nucleosome-depleted regions (NDRs). Nucleosome position at the amplicons was highly similar among developmental stages during which ORC is or is not bound, indicating that being an NDR is not sufficient to specify ORC binding. Importantly, the data suggest that nucleosomes and ORC have opposite preferences for DNA sequence and structure. We propose that nucleosome hyperacetylation promotes pre-RC assembly onto adjacent DNA sequences that are disfavored by nucleosomes but favored by ORC. PMID:26227968
Xenopus origin recognition complex (ORC) initiates DNA replication preferentially at sequences targeted by Schizosaccharomyces pombe ORC

PubMed Central

Kong, Daochun; Coleman, Thomas R.; DePamphilis, Melvin L.

2003-01-01

Budding yeast (Saccharomyces cerevisiae) origin recognition complex (ORC) requires ATP to bind specific DNA sequences, whereas fission yeast (Schizosaccharomyces pombe) ORC binds to specific, asymmetric A:T-rich sites within replication origins, independently of ATP, and frog (Xenopus laevis) ORC seems to bind DNA non-specifically. Here we show that despite these differences, ORCs are functionally conserved. Firstly, SpOrc1, SpOrc4 and SpOrc5, like those from other eukaryotes, bound ATP and exhibited ATPase activity, suggesting that ATP is required for pre-replication complex (pre-RC) assembly rather than origin specificity. Secondly, SpOrc4, which is solely responsible for binding SpORC to DNA, inhibited up to 70% of XlORC-dependent DNA replication in Xenopus egg extract by preventing XlORC from binding to chromatin and assembling pre-RCs. Chromatin-bound SpOrc4 was located at AT-rich sequences. XlORC in egg extract bound preferentially to asymmetric A:T-sequences in either bare DNA or in sperm chromatin, and it recruited XlCdc6 and XlMcm proteins to these sequences. These results reveal that XlORC initiates DNA replication preferentially at the same or similar sites to those targeted in S.pombe. PMID:12840006
A CI-Independent Form of Replicative Inhibition: Turn Off of Early Replication of Bacteriophage Lambda

PubMed Central

Hayes, Sidney; Horbay, Monique A.; Hayes, Connie

2012-01-01

Several earlier studies have described an unusual exclusion phenotype exhibited by cells with plasmids carrying a portion of the replication region of phage lambda. Cells exhibiting this inhibition phenotype (IP) prevent the plating of homo-immune and hybrid hetero-immune lambdoid phages. We have attempted to define aspects of IP, and show that it is directed to repλ phages. IP was observed in cells with plasmids containing a λ DNA fragment including oop, encoding a short OOP micro RNA, and part of the lambda origin of replication, oriλ, defined by iteron sequences ITN1-4 and an adjacent high AT-rich sequence. Transcription of the intact oop sequence from its promoter, pO is required for IP, as are iterons ITN3–4, but not the high AT-rich portion of oriλ. The results suggest that IP silencing is directed to theta mode replication initiation from an infecting repλ genome, or an induced repλ prophage. Phage mutations suppressing IP, i.e., Sip, map within, or adjacent to cro or in O, or both. Our results for plasmid based IP suggest the hypothesis that there is a natural mechanism for silencing early theta-mode replication initiation, i.e. the buildup of λ genomes with oop + oriλ+ sequence. PMID:22590552
Sequence dependency of canonical base pair opening in the DNA double helix

PubMed Central

Villa, Alessandra

2017-01-01

The flipping-out of a DNA base from the double helical structure is a key step of many cellular processes, such as DNA replication, modification and repair. Base pair opening is the first step of base flipping and the exact mechanism is still not well understood. We investigate sequence effects on base pair opening using extensive classical molecular dynamics simulations targeting the opening of 11 different canonical base pairs in two DNA sequences. Two popular biomolecular force fields are applied. To enhance sampling and calculate free energies, we bias the simulation along a simple distance coordinate using a newly developed adaptive sampling algorithm. The simulation is guided back and forth along the coordinate, allowing for multiple opening pathways. We compare the calculated free energies with those from an NMR study and check assumptions of the model used for interpreting the NMR data. Our results further show that the neighboring sequence is an important factor for the opening free energy, but also indicates that other sequence effects may play a role. All base pairs are observed to have a propensity for opening toward the major groove. The preferred opening base is cytosine for GC base pairs, while for AT there is sequence dependent competition between the two bases. For AT opening, we identify two non-canonical base pair interactions contributing to a local minimum in the free energy profile. For both AT and CG we observe long-lived interactions with water and with sodium ions at specific sites on the open base pair. PMID:28369121
FANCJ promotes DNA synthesis through G-quadruplex structures

PubMed Central

Castillo Bosch, Pau; Segura-Bayona, Sandra; Koole, Wouter; van Heteren, Jane T; Dewar, James M; Tijsterman, Marcel; Knipscheer, Puck

2014-01-01

Our genome contains many G-rich sequences, which have the propensity to fold into stable secondary DNA structures called G4 or G-quadruplex structures. These structures have been implicated in cellular processes such as gene regulation and telomere maintenance. However, G4 sequences are prone to mutations particularly upon replication stress or in the absence of specific helicases. To investigate how G-quadruplex structures are resolved during DNA replication, we developed a model system using ssDNA templates and Xenopus egg extracts that recapitulates eukaryotic G4 replication. Here, we show that G-quadruplex structures form a barrier for DNA replication. Nascent strand synthesis is blocked at one or two nucleotides from the G4. After transient stalling, G-quadruplexes are efficiently unwound and replicated. In contrast, depletion of the FANCJ/BRIP1 helicase causes persistent replication stalling at G-quadruplex structures, demonstrating a vital role for this helicase in resolving these structures. FANCJ performs this function independently of the classical Fanconi anemia pathway. These data provide evidence that the G4 sequence instability in FANCJ−/− cells and Fancj/dog1 deficient C. elegans is caused by replication stalling at G-quadruplexes. PMID:25193968
Formation of cis-diamminedichloroplatinum(II) 1,2-intrastrand cross-links on DNA is flanking-sequence independent.

PubMed

Burstyn, J N; Heiger-Bernays, W J; Cohen, S M; Lippard, S J

2000-11-01

Mapping of cis-diamminedichloroplatinum(II) (cis-DDP, cisplatin) DNA adducts over >3000 nucleotides was carried out using a replication blockage assay. The sites of inhibition of modified T4 DNA polymerase, also referred to as stop sites, were analyzed to determine the effects of local sequence context on the distribution of intrastrand cisplatin cross-links. In a 3120 base fragment from replicative form M13mp18 DNA containing 24.6% guanine, 25.5% thymine, 26.9% adenine and 23.0% cytosine, 166 individual stop sites were observed at a bound platinum/nucleotide ratio of 1-2 per thousand. The majority of stop sites (90%) occurred at G(n>2) sequences and the remainder were located at sites containing an AG dinucleotide. For all of the GG sites present in the mapped sequences, including those with Gn(>)2, 89% blocked replication, whereas for the AG sites only 17% blocked replication. These blockage sites were independent of flanking nucleotides in a sequence of N(1)G*G*N(2) where N(1), N(2) = A, C, G, T and G*G* indicates a 1,2-intrastrand platinum cross-link. The absence of long-range sequence dependence was confirmed by monitoring the reaction of cisplatin with a plasmid containing an 800 bp insert of the human telomere repeat sequence (TTAGGG)(n). Platination reactions monitored at several formal platinum/nucleotide ratios or as a function of time reveal that the telomere insert was not preferentially damaged by cisplatin. Both replication blockage and telomere-insert plasmid platination experiments indicate that cisplatin 1,2-intrastrand adducts do not form preferentially at G-rich sequences in vitro.
Analysis of simian immunodeficiency virus sequence variation in tissues of rhesus macaques with simian AIDS.

PubMed Central

Kodama, T; Mori, K; Kawahara, T; Ringler, D J; Desrosiers, R C

1993-01-01

One rhesus macaque displayed severe encephalomyelitis and another displayed severe enterocolitis following infection with molecularly cloned simian immunodeficiency virus (SIV) strain SIVmac239. Little or no free anti-SIV antibody developed in these two macaques, and they died relatively quickly (4 to 6 months) after infection. Manifestation of the tissue-specific disease in these macaques was associated with the emergence of variants with high replicative capacity for macrophages and primary infection of tissue macrophages. The nature of sequence variation in the central region (vif, vpr, and vpx), the env gene, and the nef long terminal repeat (LTR) region in brain, colon, and other tissues was examined to see whether specific genetic changes were associated with SIV replication in brain or gut. Sequence analysis revealed strong conservation of the intergenic central region, nef, and the LTR. However, analysis of env sequences in these two macaques and one other revealed significant, interesting patterns of sequence variation. (i) Changes in env that were found previously to contribute to the replicative ability of SIVmac for macrophages in culture were present in the tissues of these animals. (ii) The greatest variability was located in the regions between V1 and V2 and from "V3" through C3 in gp120, which are different in location from the variable regions observed previously in animals with strong antibody responses and long-term persistent infection. (iii) The predominant sequence change of D-->N at position 385 in C3 is most surprising, since this change in both SIV and human immunodeficiency virus type 1 has been associated with dramatically diminished affinity for CD4 and replication in vitro. (iv) The nature of sequence changes at some positions (146, 178, 345, 385, and "V3") suggests that viral replication in brain and gut may be facilitated by specific sequence changes in env in addition to those that impart a general ability to replicate well in macrophages. These results demonstrate that complex selective pressures, including immune responses and varying cell and tissue specificity, can influence the nature of sequence changes in env. Images PMID:8411355
Role of the Adenovirus DNA-Binding Protein in In Vitro Adeno-Associated Virus DNA Replication

PubMed Central

Ward, Peter; Dean, Frank B.; O’Donnell, Michael E.; Berns, Kenneth I.

1998-01-01

A basic question in adeno-associated virus (AAV) biology has been whether adenovirus (Ad) infection provided any function which directly promoted replication of AAV DNA. Previously in vitro assays for AAV DNA replication, using linear duplex AAV DNA as the template, uninfected or Ad-infected HeLa cell extracts, and exogenous AAV Rep protein, demonstrated that Ad infection provides a direct helper effect for AAV DNA replication. It was shown that the nature of this helper effect was to increase the processivity of AAV DNA replication. Left unanswered was the question of whether this effect was the result of cellular factors whose activity was enhanced by Ad infection or was the result of direct participation of Ad proteins in AAV DNA replication. In this report, we show that in the in vitro assay, enhancement of processivity occurs with the addition of either the Ad DNA-binding protein (Ad-DBP) or the human single-stranded DNA-binding protein (replication protein A [RPA]). Clearly Ad-DBP is present after Ad infection but not before, whereas the cellular level of RPA is not apparently affected by Ad infection. However, we have not measured possible modifications of RPA which might occur after Ad infection and affect AAV DNA replication. When the substrate for replication was an AAV genome inserted into a plasmid vector, RPA was not an effective substitute for Ad-DBP. Extracts supplemented with Ad-DBP preferentially replicated AAV sequences rather than adjacent vector sequences; in contrast, extracts supplemented with RPA preferentially replicated vector sequences. PMID:9420241
Fundamental Bounds for Sequence Reconstruction from Nanopore Sequencers.

PubMed

Magner, Abram; Duda, Jarosław; Szpankowski, Wojciech; Grama, Ananth

2016-06-01

Nanopore sequencers are emerging as promising new platforms for high-throughput sequencing. As with other technologies, sequencer errors pose a major challenge for their effective use. In this paper, we present a novel information theoretic analysis of the impact of insertion-deletion (indel) errors in nanopore sequencers. In particular, we consider the following problems: (i) for given indel error characteristics and rate, what is the probability of accurate reconstruction as a function of sequence length; (ii) using replicated extrusion (the process of passing a DNA strand through the nanopore), what is the number of replicas needed to accurately reconstruct the true sequence with high probability? Our results provide a number of important insights: (i) the probability of accurate reconstruction of a sequence from a single sample in the presence of indel errors tends quickly (i.e., exponentially) to zero as the length of the sequence increases; and (ii) replicated extrusion is an effective technique for accurate reconstruction. We show that for typical distributions of indel errors, the required number of replicas is a slow function (polylogarithmic) of sequence length - implying that through replicated extrusion, we can sequence large reads using nanopore sequencers. Moreover, we show that in certain cases, the required number of replicas can be related to information-theoretic parameters of the indel error distributions.
Analysis of the temporal program of replication initiation in yeast chromosomes.

PubMed

Friedman, K L; Raghuraman, M K; Fangman, W L; Brewer, B J

1995-01-01

The multiple origins of eukaryotic chromosomes vary in the time of their initiation during S phase. In the chromosomes of Saccharomyces cerevisiae the presence of a functional telomere causes nearby origins to delay initiation until the second half of S phase. The key feature of telomeres that causes the replication delay is the telomeric sequence (C(1-3)A/G(1-3)T) itself and not the proximity of the origin to a DNA end. A second group of late replicating origins has been found at an internal position on chromosome XIV. Four origins, spanning approximately 140 kb, initiate replication in the second half of S phase. At least two of these internal origins maintain their late replication time on circular plasmids. Each of these origins can be separated into two functional elements: those sequences that provide origin function and those that impose late activation. Because the assay for determining replication time is costly and laborious, it has not been possible to analyze in detail these 'late' elements. We report here the development of two new assays for determining replication time. The first exploits the expression of the Escherichia coli dam methylase in yeast and the characteristic period of hemimethylation that transiently follows the passage of a replication fork. The second uses quantitative hybridization to detect two-fold differences in the amount of specific restriction fragments as a function of progress through S phase. The novel aspect of this assay is the creation in vivo of a non-replicating DNA sequence by site-specific pop-out recombination. This non-replicating fragment acts as an internal control for copy number within and between samples. Both of these techniques are rapid and much less costly than the more conventional density transfer experiments that require CsCl gradients to detect replicated DNA. With these techniques it should be possible to identify the sequences responsible for late initiation, to search for other late replicating regions in the genome, and to begin to analyze the effect that altering the temporal program has on chromosome function.
Construction and production of oncotropic vectors, derived from MVM(p), that share reduced sequence homology with helper plasmids.

PubMed

Clément, Nathalie; Velu, Thierry; Brandenburger, Annick

2002-09-01

The production of currently available vectors derived from autonomous parvoviruses requires the expression of capsid proteins in trans, from helper sequences. Cotransfection of a helper plasmid always generates significant amounts of replication-competent virus (RCV) that can be reduced by the integration of helper sequences into a packaging cell line. Although stocks of minute virus of mice (MVM)-based vectors with no detectable RCV could be produced by transfection into packaging cells; the latter appear after one or two rounds of replication, precluding further amplification of the vector stock. Indeed, once RCVs become detectable, they are efficiently amplified and rapidly take over the culture. Theoretically RCV-free vector stocks could be produced if all homology between vector and helper DNA is eliminated, thus preventing homologous recombination. We constructed new vectors based on the structure of spontaneously occurring defective particles of MVM. Based on published observations related to the size of vectors and the sequence of the viral origin of replication, these vectors were modified by the insertion of foreign DNA sequences downstream of the transgene and by the introduction of a consensus NS-1 nick site near the origin of replication to optimize their production. In one of the vectors the inserted fragment of mouse genomic DNA had a synergistic effect with the modified origin of replication in increasing vector production.
Varicella-zoster virus (VZV) origin of DNA replication oriS influences origin-dependent DNA replication and flanking gene transcription.

PubMed

Khalil, Mohamed I; Sommer, Marvin H; Hay, John; Ruyechan, William T; Arvin, Ann M

2015-07-01

The VZV genome has two origins of DNA replication (oriS), each of which consists of an AT-rich sequence and three origin binding protein (OBP) sites called Box A, C and B. In these experiments, the mutation in the core sequence CGC of the Box A and C not only inhibited DNA replication but also inhibited both ORF62 and ORF63 expression in reporter gene assays. In contrast the Box B mutation did not influence DNA replication or flanking gene transcription. These results suggest that efficient DNA replication enhances ORF62 and ORF63 transcription. Recombinant viruses carrying these mutations in both sites and one with a deletion of the whole oriS were constructed. Surprisingly, the recombinant virus lacking both copies of oriS retained the capacity to replicate in melanoma and HELF cells suggesting that VZV has another origin of DNA replication. Copyright © 2015 Elsevier Inc. All rights reserved.
Comparative analysis of seven viral nuclear export signals (NESs) reveals the crucial role of nuclear export mediated by the third NES consensus sequence of nucleoprotein (NP) in influenza A virus replication.

PubMed

Chutiwitoonchai, Nopporn; Kakisaka, Michinori; Yamada, Kazunori; Aida, Yoko

2014-01-01

The assembly of influenza virus progeny virions requires machinery that exports viral genomic ribonucleoproteins from the cell nucleus. Currently, seven nuclear export signal (NES) consensus sequences have been identified in different viral proteins, including NS1, NS2, M1, and NP. The present study examined the roles of viral NES consensus sequences and their significance in terms of viral replication and nuclear export. Mutation of the NP-NES3 consensus sequence resulted in a failure to rescue viruses using a reverse genetics approach, whereas mutation of the NS2-NES1 and NS2-NES2 sequences led to a strong reduction in viral replication kinetics compared with the wild-type sequence. While the viral replication kinetics for other NES mutant viruses were also lower than those of the wild-type, the difference was not so marked. Immunofluorescence analysis after transient expression of NP-NES3, NS2-NES1, or NS2-NES2 proteins in host cells showed that they accumulated in the cell nucleus. These results suggest that the NP-NES3 consensus sequence is mostly required for viral replication. Therefore, each of the hydrophobic (Φ) residues within this NES consensus sequence (Φ1, Φ2, Φ3, or Φ4) was mutated, and its viral replication and nuclear export function were analyzed. No viruses harboring NP-NES3 Φ2 or Φ3 mutants could be rescued. Consistent with this, the NP-NES3 Φ2 and Φ3 mutants showed reduced binding affinity with CRM1 in a pull-down assay, and both accumulated in the cell nucleus. Indeed, a nuclear export assay revealed that these mutant proteins showed lower nuclear export activity than the wild-type protein. Moreover, the Φ2 and Φ3 residues (along with other Φ residues) within the NP-NES3 consensus were highly conserved among different influenza A viruses, including human, avian, and swine. Taken together, these results suggest that the Φ2 and Φ3 residues within the NP-NES3 protein are important for its nuclear export function during viral replication.
Improvement and Optimization of Two Engineered Phage Resistance Mechanisms in Lactococcus lactis

PubMed Central

McGrath, Stephen; Fitzgerald, Gerald F.; van Sinderen, Douwe

2001-01-01

Homologous replication module genes were identified for four P335 type phages. DNA sequence analysis revealed that all four phages exhibited more than 90% DNA homology for at least two genes, designated rep2009 and orf17. One of these genes, rep2009, codes for a putative replisome organizer protein and contains an assumed origin of phage DNA replication (ori2009), which was identical for all four phages. DNA fragments representing the ori2009 sequence confer a phage-encoded resistance (Per) phenotype on lactococcal hosts when they are supplied on a high-copy-number vector. Furthermore, cloning multiple copies of the ori2009 sequence was found to increase the effectiveness of the Per phenotype conferred. A number of antisense plasmids targeting specific genes of the replication module were constructed. Two separate plasmids targeting rep2009 and orf17 were found to efficiently inhibit proliferation of all four phages by interfering with intracellular phage DNA replication. These results represent two highly effective strategies for inhibiting bacteriophage proliferation, and they also identify a novel gene, orf17, which appears to be important for phage DNA replication. Furthermore, these results indicate that although the actual mechanisms of DNA replication are very similar, if not identical, for all four phages, expression of the replication genes is significantly different in each case. PMID:11157223
Sequencing-based breast cancer diagnostics as an alternative to routine biomarkers.

PubMed

Rantalainen, Mattias; Klevebring, Daniel; Lindberg, Johan; Ivansson, Emma; Rosin, Gustaf; Kis, Lorand; Celebioglu, Fuat; Fredriksson, Irma; Czene, Kamila; Frisell, Jan; Hartman, Johan; Bergh, Jonas; Grönberg, Henrik

2016-11-30

Sequencing-based breast cancer diagnostics have the potential to replace routine biomarkers and provide molecular characterization that enable personalized precision medicine. Here we investigate the concordance between sequencing-based and routine diagnostic biomarkers and to what extent tumor sequencing contributes clinically actionable information. We applied DNA- and RNA-sequencing to characterize tumors from 307 breast cancer patients with replication in up to 739 patients. We developed models to predict status of routine biomarkers (ER, HER2,Ki-67, histological grade) from sequencing data. Non-routine biomarkers, including mutations in BRCA1, BRCA2 and ERBB2(HER2), and additional clinically actionable somatic alterations were also investigated. Concordance with routine diagnostic biomarkers was high for ER status (AUC = 0.95;AUC(replication) = 0.97) and HER2 status (AUC = 0.97;AUC(replication) = 0.92). The transcriptomic grade model enabled classification of histological grade 1 and histological grade 3 tumors with high accuracy (AUC = 0.98;AUC(replication) = 0.94). Clinically actionable mutations in BRCA1, BRCA2 and ERBB2(HER2) were detected in 5.5% of patients, while 53% had genomic alterations matching ongoing or concluded breast cancer studies. Sequencing-based molecular profiling can be applied as an alternative to histopathology to determine ER and HER2 status, in addition to providing improved tumor grading and clinically actionable mutations and molecular subtypes. Our results suggest that sequencing-based breast cancer diagnostics in a near future can replace routine biomarkers.

The impact of sampling, PCR, and sequencing replication on discerning changes in drinking water bacterial community over diurnal time-scales.

PubMed

Bautista-de Los Santos, Quyen Melina; Schroeder, Joanna L; Blakemore, Oliver; Moses, Jonathan; Haffey, Mark; Sloan, William; Pinto, Ameet J

2016-03-01

High-throughput and deep DNA sequencing, particularly amplicon sequencing, is being increasingly utilized to reveal spatial and temporal dynamics of bacterial communities in drinking water systems. Whilst the sampling and methodological biases associated with PCR and sequencing have been studied in other environments, they have not been quantified for drinking water. These biases are likely to have the greatest effect on the ability to characterize subtle spatio-temporal patterns influenced by process/environmental conditions. In such cases, intra-sample variability may swamp any underlying small, systematic variation. To evaluate this, we undertook a study with replication at multiple levels including sampling sites, sample collection, PCR amplification, and high throughput sequencing of 16S rRNA amplicons. The variability inherent to the PCR amplification and sequencing steps is significant enough to mask differences between bacterial communities from replicate samples. This was largely driven by greater variability in detection of rare bacteria (relative abundance <0.01%) across PCR/sequencing replicates as compared to replicate samples. Despite this, we captured significant changes in bacterial community over diurnal time-scales and find that the extent and pattern of diurnal changes is specific to each sampling location. Further, we find diurnal changes in bacterial community arise due to differences in the presence/absence of the low abundance bacteria and changes in the relative abundance of dominant bacteria. Finally, we show that bacterial community composition is significantly different across sampling sites for time-periods during which there are typically rapid changes in water use. This suggests hydraulic changes (driven by changes in water demand) contribute to shaping the bacterial community in bulk drinking water over diurnal time-scales. Copyright © 2015 Elsevier Ltd. All rights reserved.
Efficient experimental design and analysis strategies for the detection of differential expression using RNA-Sequencing

PubMed Central

2012-01-01

Background RNA sequencing (RNA-Seq) has emerged as a powerful approach for the detection of differential gene expression with both high-throughput and high resolution capabilities possible depending upon the experimental design chosen. Multiplex experimental designs are now readily available, these can be utilised to increase the numbers of samples or replicates profiled at the cost of decreased sequencing depth generated per sample. These strategies impact on the power of the approach to accurately identify differential expression. This study presents a detailed analysis of the power to detect differential expression in a range of scenarios including simulated null and differential expression distributions with varying numbers of biological or technical replicates, sequencing depths and analysis methods. Results Differential and non-differential expression datasets were simulated using a combination of negative binomial and exponential distributions derived from real RNA-Seq data. These datasets were used to evaluate the performance of three commonly used differential expression analysis algorithms and to quantify the changes in power with respect to true and false positive rates when simulating variations in sequencing depth, biological replication and multiplex experimental design choices. Conclusions This work quantitatively explores comparisons between contemporary analysis tools and experimental design choices for the detection of differential expression using RNA-Seq. We found that the DESeq algorithm performs more conservatively than edgeR and NBPSeq. With regard to testing of various experimental designs, this work strongly suggests that greater power is gained through the use of biological replicates relative to library (technical) replicates and sequencing depth. Strikingly, sequencing depth could be reduced as low as 15% without substantial impacts on false positive or true positive rates. PMID:22985019
Efficient experimental design and analysis strategies for the detection of differential expression using RNA-Sequencing.

PubMed

Robles, José A; Qureshi, Sumaira E; Stephen, Stuart J; Wilson, Susan R; Burden, Conrad J; Taylor, Jennifer M

2012-09-17

RNA sequencing (RNA-Seq) has emerged as a powerful approach for the detection of differential gene expression with both high-throughput and high resolution capabilities possible depending upon the experimental design chosen. Multiplex experimental designs are now readily available, these can be utilised to increase the numbers of samples or replicates profiled at the cost of decreased sequencing depth generated per sample. These strategies impact on the power of the approach to accurately identify differential expression. This study presents a detailed analysis of the power to detect differential expression in a range of scenarios including simulated null and differential expression distributions with varying numbers of biological or technical replicates, sequencing depths and analysis methods. Differential and non-differential expression datasets were simulated using a combination of negative binomial and exponential distributions derived from real RNA-Seq data. These datasets were used to evaluate the performance of three commonly used differential expression analysis algorithms and to quantify the changes in power with respect to true and false positive rates when simulating variations in sequencing depth, biological replication and multiplex experimental design choices. This work quantitatively explores comparisons between contemporary analysis tools and experimental design choices for the detection of differential expression using RNA-Seq. We found that the DESeq algorithm performs more conservatively than edgeR and NBPSeq. With regard to testing of various experimental designs, this work strongly suggests that greater power is gained through the use of biological replicates relative to library (technical) replicates and sequencing depth. Strikingly, sequencing depth could be reduced as low as 15% without substantial impacts on false positive or true positive rates.
Elements in the transcriptional regulatory region flanking herpes simplex virus type 1 oriS stimulate origin function.

PubMed

Wong, S W; Schaffer, P A

1991-05-01

Like other DNA-containing viruses, the three origins of herpes simplex virus type 1 (HSV-1) DNA replication are flanked by sequences containing transcriptional regulatory elements. In a transient plasmid replication assay, deletion of sequences comprising the transcriptional regulatory elements of ICP4 and ICP22/47, which flank oriS, resulted in a greater than 80-fold decrease in origin function compared with a plasmid, pOS-822, which retains these sequences. In an effort to identify specific cis-acting elements responsible for this effect, we conducted systematic deletion analysis of the flanking region with plasmid pOS-822 and tested the resulting mutant plasmids for origin function. Stimulation by cis-acting elements was shown to be both distance and orientation dependent, as changes in either parameter resulted in a decrease in oriS function. Additional evidence for the stimulatory effect of flanking sequences on origin function was demonstrated by replacement of these sequences with the cytomegalovirus immediate-early promoter, resulting in nearly wild-type levels of oriS function. In competition experiments, cotransfection of cells with the test plasmid, pOS-822, and increasing molar concentrations of a competitor plasmid which contained the ICP4 and ICP22/47 transcriptional regulatory regions but lacked core origin sequences resulted in a significant reduction in the replication efficiency of pOS-822, demonstrating that factors which bind specifically to the oriS-flanking sequences are likely involved as auxiliary proteins in oriS function. Together, these studies demonstrate that trans-acting factors and the sites to which they bind play a critical role in the efficiency of HSV-1 DNA replication from oriS in transient-replication assays.
Epigenetically-inherited centromere and neocentromere DNA replicates earliest in S-phase.

PubMed

Koren, Amnon; Tsai, Hung-Ji; Tirosh, Itay; Burrack, Laura S; Barkai, Naama; Berman, Judith

2010-08-19

Eukaryotic centromeres are maintained at specific chromosomal sites over many generations. In the budding yeast Saccharomyces cerevisiae, centromeres are genetic elements defined by a DNA sequence that is both necessary and sufficient for function; whereas, in most other eukaryotes, centromeres are maintained by poorly characterized epigenetic mechanisms in which DNA has a less definitive role. Here we use the pathogenic yeast Candida albicans as a model organism to study the DNA replication properties of centromeric DNA. By determining the genome-wide replication timing program of the C. albicans genome, we discovered that each centromere is associated with a replication origin that is the first to fire on its respective chromosome. Importantly, epigenetic formation of new ectopic centromeres (neocentromeres) was accompanied by shifts in replication timing, such that a neocentromere became the first to replicate and became associated with origin recognition complex (ORC) components. Furthermore, changing the level of the centromere-specific histone H3 isoform led to a concomitant change in levels of ORC association with centromere regions, further supporting the idea that centromere proteins determine origin activity. Finally, analysis of centromere-associated DNA revealed a replication-dependent sequence pattern characteristic of constitutively active replication origins. This strand-biased pattern is conserved, together with centromere position, among related strains and species, in a manner independent of primary DNA sequence. Thus, inheritance of centromere position is correlated with a constitutively active origin of replication that fires at a distinct early time. We suggest a model in which the distinct timing of DNA replication serves as an epigenetic mechanism for the inheritance of centromere position.
27nt-RNAs guide histone variant deposition via 'RNA-induced DNA replication interference' and thus transmit parental genome partitioning in Stylonychia.

PubMed

Postberg, Jan; Jönsson, Franziska; Weil, Patrick Philipp; Bulic, Aneta; Juranek, Stefan Andreas; Lipps, Hans-Joachim

2018-06-12

During sexual reproduction in the unicellular ciliate Stylonychia somatic macronuclei differentiate from germline micronuclei. Thereby, programmed sequence reduction takes place, leading to the elimination of > 95% of germline sequences, which priorly adopt heterochromatin structure via H3K27me3. Simultaneously, 27nt-ncRNAs become synthesized from parental transcripts and are bound by the Argonaute protein PIWI1. These 27nt-ncRNAs cover sequences destined to the developing macronucleus and are thought to protect them from degradation. We provide evidence and propose that RNA/DNA base-pairing guides PIWI1/27nt-RNA complexes to complementary macronucleus-destined DNA target sequences, hence transiently causing locally stalled replication during polytene chromosome formation. This spatiotemporal delay enables the selective deposition of temporarily available histone H3.4K27me3 nucleosomes at all other sequences being continuously replicated, thus dictating their prospective heterochromatin structure before becoming developmentally eliminated. Concomitantly, 27nt-RNA-covered sites remain protected. We introduce the concept of 'RNA-induced DNA replication interference' and explain how the parental functional genome partition could become transmitted to the progeny.
Marine amoebae with cytoplasmic and perinuclear symbionts deeply branching in the Gammaproteobacteria

PubMed Central

Schulz, Frederik; Tyml, Tomáš; Pizzetti, Ilaria; Dyková, Iva; Fazi, Stefano; Kostka, Martin; Horn, Matthias

2015-01-01

Amoebae play an important ecological role as predators in microbial communities. They also serve as niche for bacterial replication, harbor endosymbiotic bacteria and have contributed to the evolution of major human pathogens. Despite their high diversity, marine amoebae and their association with bacteria are poorly understood. Here we describe the isolation and characterization of two novel marine amoebae together with their bacterial endosymbionts, tentatively named ‘Candidatus Occultobacter vannellae’ and ‘Candidatus Nucleophilum amoebae’. While one amoeba strain is related to Vannella, a genus common in marine habitats, the other represents a novel lineage in the Amoebozoa. The endosymbionts showed only low similarity to known bacteria (85–88% 16S rRNA sequence similarity) but together with other uncultured marine bacteria form a sister clade to the Coxiellaceae. Using fluorescence in situ hybridization and transmission electron microscopy, identity and intracellular location of both symbionts were confirmed; one was replicating in host-derived vacuoles, whereas the other was located in the perinuclear space of its amoeba host. This study sheds for the first time light on a so far neglected group of protists and their bacterial symbionts. The newly isolated strains represent easily maintainable model systems and pave the way for further studies on marine associations between amoebae and bacterial symbionts. PMID:26303516
Single-stranded DNA-binding Protein in Vitro Eliminates the Orientation-dependent Impediment to Polymerase Passage on CAG/CTG Repeats*

PubMed Central

Delagoutte, Emmanuelle; Goellner, Geoffrey M.; Guo, Jie; Baldacci, Giuseppe; McMurray, Cynthia T.

2008-01-01

Small insertions and deletions of trinucleotide repeats (TNRs) can occur by polymerase slippage and hairpin formation on either template or newly synthesized strands during replication. Although not predicted by a slippage model, deletions occur preferentially when 5′-CTG is in the lagging strand template and are highly favored over insertion events in rapidly replicating cells. The mechanism for the deletion bias and the orientation dependence of TNR instability is poorly understood. We report here that there is an orientation-dependent impediment to polymerase progression on 5′-CAG and 5′-CTG repeats that can be relieved by the binding of single-stranded DNA-binding protein. The block depends on the primary sequence of the TNR but does not correlate with the thermodynamic stability of hairpins. The orientation-dependent block of polymerase passage is the strongest when 5′-CAG is the template. We propose a “template-push” model in which the slow speed of DNA polymerase across the 5′-CAG leading strand template creates a threat to helicase-polymerase coupling. To prevent uncoupling, the TNR template is pushed out and by-passed. Hairpins do not cause the block, but appear to occur as a consequence of polymerase pass-over. PMID:18263578
A CO-FISH assay to assess sister chromatid segregation patterns in mitosis of mouse embryonic stem cells.

PubMed

Sauer, Stephan; Burkett, Sandra S; Lewandoski, Mark; Klar, Amar J S

2013-05-01

Sister chromatids contain identical DNA sequence but are chiral with respect to both their helical handedness and their replication history. Emerging evidence from various model organisms suggests that certain stem cells segregate sister chromatids nonrandomly to either maintain genome integrity or to bias cellular differentiation in asymmetric cell divisions. Conventional methods for tracing of old vs. newly synthesized DNA strands generally lack resolution for individual chromosomes and employ halogenated thymidine analogs with profound cytotoxic effects on rapidly dividing cells. Here, we present a modified chromosome orientation fluorescence in situ hybridization (CO-FISH) assay, where identification of individual chromosomes and their replication history is achieved in subsequent hybridization steps with chromosome-specific DNA probes and PNA telomere probes. Importantly, we tackle the issue of BrdU cytotoxicity and show that our method is compatible with normal mouse ES cell biology, unlike a recently published related protocol. Results from our CO-FISH assay show that mitotic segregation of mouse chromosome 7 is random in ES cells, which contrasts previously published results from our laboratory and settles a controversy. Our straightforward protocol represents a useful resource for future studies on chromatid segregation patterns of in vitro-cultured cells from distinct model organisms.
Hda inactivation of DnaA is the predominant mechanism preventing hyperinitiation of Escherichia coli DNA replication.

PubMed

Camara, Johanna E; Breier, Adam M; Brendler, Therese; Austin, Stuart; Cozzarelli, Nicholas R; Crooke, Elliott

2005-08-01

Initiation of DNA replication from the Escherichia coli chromosomal origin is highly regulated, assuring that replication occurs precisely once per cell cycle. Three mechanisms for regulation of replication initiation have been proposed: titration of free DnaA initiator protein by the datA locus, sequestration of newly replicated origins by SeqA protein and regulatory inactivation of DnaA (RIDA), in which active ATP-DnaA is converted to the inactive ADP-bound form. DNA microarray analyses showed that the level of initiation in rapidly growing cells that lack datA was indistinguishable from that in wild-type cells, and that the absence of SeqA protein caused only a modest increase in initiation, in agreement with flow-cytometry data. In contrast, cells lacking Hda overinitiated replication twofold, implicating RIDA as the predominant mechanism preventing extra initiation events in a cell cycle.
Association of the Bacillus subtilis Chromosome with the Cell Membrane: Resolution of Free and Bound Deoxyribonucleic Acid on Renografin Gradients

PubMed Central

Ivarie, Robert D.; Pène, Jacques J.

1970-01-01

Linear density gradients of Renografin have resolved two components of bacterial deoxyribonucleic acid (DNA) in sheared lysates. Component 1, at equilibrium density after 5 hr of centrifugation, is enriched for newly synthesized DNA and markers near the origin and terminus of replication. It contains 5% of total cellular protein, 25% of the phospholipids, 30 to 50% of the DNA, 4 to 11% of unstable ribonucleic acid (RNA), RNA polymerase, and low amounts of DNA polymerase. The material is sensitive to Pronase and Sarkosyl. In unsheared lysates, all of the DNA forms a band at this position. Shearing the lysate generates a slow-sedimenting fraction of DNA (component 2) which contains more uniformly labeled than newly synthesized DNA. These observations suggest that replicating DNA and DNA at the origin and possibly the terminus of replication are associated with membrane. The amount of uniformly labeled DNA in component 1 and an estimate of the number of chromosomal fragments suggest that other parts of the chromosome are possibly associated with the membrane. PMID:4992373
The right half of the Escherichia coli replication origin is not essential for viability, but facilitates multi-forked replication

PubMed Central

Stepankiw, Nicholas; Kaidow, Akihiro; Boye, Erik; Bates, David

2010-01-01

Summary Replication initiation is a key event in the cell cycle of all organisms and oriC, the replication origin in Escherichia coli, serves as the prototypical model for this process. The minimal sequence required for oriC function was originally determined entirely from plasmid studies using cloned origin fragments, which have previously been shown to differ dramatically in sequence requirement from the chromosome. Using an in vivo recombineering strategy to exchange wt oriCs for mutated ones regardless of whether they are functional origins or not, we have determined the minimal origin sequence that will support chromosome replication. Nearly the entire right half of oriC could be deleted without loss of origin function, demanding a reassessment of existing models for initiation. Cells carrying the new DnaA box-depleted 163 bp minimal oriC exhibited little or no loss of fitness under slow-growth conditions, but were sensitive to rich medium, suggesting that the dense packing of initiator binding sites that is a hallmark of prokaryotic origins, has likely evolved to support the increased demands of multi-forked replication. PMID:19737351
DISCOVERY OF THREE NOVEL COCCIDIAN PARASITES INFECTING CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS), WITH EVIDENCE OF SEXUAL REPLICATION AND INTERSPECIES PATHOGENICITY

PubMed Central

Colegrove, Kathleen M.; Grigg, Michael E.; Carlson-Bremer, Daphne; Miller, Robin H.; Gulland, Frances M. D.; Ferguson, David J. P.; Rejmanek, Daniel; Barr, Bradd C.; Nordhausen, Robert; Melli, Ann C.; Conrad, Patricia A.

2016-01-01

Enteric protozoal infection was identified in 5 stranded California sea lions (Zalophus californianus). Microscopically, the apical cytoplasm of distal jejunal enterocytes contained multiple stages of coccidian parasites, including schizonts with merozoites and spherical gametocytes, which were morphologically similar to coccidians. By histopathology, organisms appeared to be confined to the intestine and accompanied by only mild enteritis. Using electron microscopy, both sexual (microgametocytes, macrogamonts) and asexual (schizonts, merozoites) coccidian stages were identified in enterocytes within parasitophorous vacuoles, consistent with apicomplexan development in a definitive host. Serology was negative for tissue cyst-forming coccidians, and immunohistochemistry for Toxoplasma gondii was inconclusive and negative for Neospora caninum and Sarcocystis neurona. Analysis of ITS-1 gene sequences amplified from frozen or formalin-fixed paraffin-embedded intestinal sections identified DNA sequences with closest homology to Neospora sp. (80%); these novel sequences were referred to as belonging to coccidian parasites ‘‘A,’’ ‘‘B,’’ and ‘‘C.’’ Subsequent molecular analyses completed on a neonatal harbor seal (Phoca vitulina) with protozoal lymphadenitis, hepatitis, myocarditis, and encephalitis showed that it was infected with a coccidian parasite bearing the ‘‘C’’ sequence type. Our results indicate that sea lions likely serve as definitive hosts for 3 newly described coccidian parasites, at least 1 of which is pathogenic in a marine mammal intermediate host species. PMID:21495828
Recovery of infectious virus from full-length cowpox virus (CPXV) DNA cloned as a bacterial artificial chromosome (BAC)

PubMed Central

2011-01-01

Transmission from pet rats and cats to humans as well as severe infection in felids and other animal species have recently drawn increasing attention to cowpox virus (CPXV). We report the cloning of the entire genome of cowpox virus strain Brighton Red (BR) as a bacterial artificial chromosome (BAC) in Escherichia coli and the recovery of infectious virus from cloned DNA. Generation of a full-length CPXV DNA clone was achieved by first introducing a mini-F vector, which allows maintenance of large circular DNA in E. coli, into the thymidine kinase locus of CPXV by homologous recombination. Circular replication intermediates were then electroporated into E. coli DH10B cells. Upon successful establishment of the infectious BR clone, we modified the full-length clone such that recombination-mediated excision of bacterial sequences can occur upon transfection in eukaryotic cells. This self-excision of the bacterial replicon is made possible by a sequence duplication within mini-F sequences and allows recovery of recombinant virus progeny without remaining marker or vector sequences. The in vitro growth properties of viruses derived from both BAC clones were determined and found to be virtually indistinguishable from those of parental, wild-type BR. Finally, the complete genomic sequence of the infectious clone was determined and the cloned viral genome was shown to be identical to that of the parental virus. In summary, the generated infectious clone will greatly facilitate studies on individual genes and pathogenesis of CPXV. Moreover, the vector potential of CPXV can now be more systematically explored using this newly generated tool. PMID:21314965
A label-free ultrasensitive fluorescence detection of viable Salmonella enteritidis using enzyme-induced cascade two-stage toehold strand-displacement-driven assembly of G-quadruplex DNA.

PubMed

Zhang, Peng; Liu, Hui; Ma, Suzhen; Men, Shuai; Li, Qingzhou; Yang, Xin; Wang, Hongning; Zhang, Anyun

2016-06-15

The harm of Salmonella enteritidis (S. enteritidis ) to public health mainly by contaminating fresh food and water emphasizes the urgent need for rapid detection techniques to help control the spread of the pathogen. In this assay, an newly designed capture probe complex that contained specific S. enteritidis-aptamer and hybridized signal target sequence was used for viable S. enteritidis recognition directly. In the presence of the target S. enteritidis, single-stranded target sequences were liberated and initiated the replication-cleavage reaction, producing numerous G-quadruplex structures with a linker on the 3'-end. And then, the sensing system took innovative advantage of quadratic linker-induced strand-displacement for the first time to release target sequence in succession, leading to the cyclic reuse of the target sequences and cascade signal amplification, thereby achieving the successive production of G-quadruplex structures. The fluorescent dye, N-Methyl mesoporphyrin IX, binded to these G-quadruplex structures and generated significantly enhanced fluorescent signals to achieve highly sensitive detection of S. enteritidis down to 60 CFU/mL with a linear range from 10(2) to 10(7)CFU/mL. By coupling the cascade two-stage target sequences-recyclable toehold strand-displacement with aptamer-based target recognition successfully, it is the first report on a novel non-label, modification-free and DNA extraction-free ultrasensitive fluorescence biosensor for detecting viable S. enteritidis directly, which can discriminate from dead S. enteritidis. Copyright © 2016 Elsevier B.V. All rights reserved.
Effect of Lamina Thickness of Prepreg on the Surface Accuracy of Carbon Fiber Composite Space Mirrors

NASA Astrophysics Data System (ADS)

Yang, Zhiyong; Tang, Zhanwen; Xie, Yongjie; Shi, Hanqiao; Zhang, Boming; Guo, Hongjun

2018-02-01

Composite space mirror can completely replicate the high-precision surface of mould by replication process, but the actual surface accuracy of the replication composite mirror always decreases. Lamina thickness of prepreg affects the layers and layup sequence of composite space mirror, and which would affect surface accuracy of space mirror. In our research, two groups of contrasting cases through finite element analyses (FEA) and comparative experiments were studied; the effect of different lamina thicknesses of prepreg and corresponding lay-up sequences was focused as well. We describe a special analysis model, validated process and result analysis. The simulated and measured surface figures both get the same conclusion. Reducing lamina thickness of prepreg used in replicating composite space mirror is propitious to optimal design of layup sequence for fabricating composite mirror, and could improve its surface accuracy.
Disintegration of Nascent Replication Bubbles during Thymine Starvation Triggers RecA- and RecBCD-dependent Replication Origin Destruction*

PubMed Central

Kuong, Kawai J.; Kuzminov, Andrei

2012-01-01

Thymineless death strikes cells unable to synthesize DNA precursor dTTP, with the nature of chromosomal damage still unclear. Thymine starvation stalls replication forks, whereas accumulating evidence indicates the replication origin is also affected. Using a novel DNA labeling technique, here we show that replication slowly continues in thymine-starved cells, but the newly synthesized DNA becomes fragmented and degraded. This degradation apparently releases enough thymine to sustain initiation of new replication bubbles from the chromosomal origin, which destabilizes the origin in a RecA-dependent manner. Marker frequency analysis with gene arrays 1) reveals destruction of the origin-centered chromosomal segment in RecA+ cells; 2) confirms origin accumulation in the recA mutants; and 3) identifies the sites around the origin where destruction initiates in the recBCD mutants. We propose that thymineless cells convert persistent single-strand gaps behind replication forks into double-strand breaks, using the released thymine for new initiations, whereas subsequent disintegration of small replication bubbles causes replication origin destruction. PMID:22621921
Optimizing high performance computing workflow for protein functional annotation.

PubMed

Stanberry, Larissa; Rekepalli, Bhanu; Liu, Yuan; Giblock, Paul; Higdon, Roger; Montague, Elizabeth; Broomall, William; Kolker, Natali; Kolker, Eugene

2014-09-10

Functional annotation of newly sequenced genomes is one of the major challenges in modern biology. With modern sequencing technologies, the protein sequence universe is rapidly expanding. Newly sequenced bacterial genomes alone contain over 7.5 million proteins. The rate of data generation has far surpassed that of protein annotation. The volume of protein data makes manual curation infeasible, whereas a high compute cost limits the utility of existing automated approaches. In this work, we present an improved and optmized automated workflow to enable large-scale protein annotation. The workflow uses high performance computing architectures and a low complexity classification algorithm to assign proteins into existing clusters of orthologous groups of proteins. On the basis of the Position-Specific Iterative Basic Local Alignment Search Tool the algorithm ensures at least 80% specificity and sensitivity of the resulting classifications. The workflow utilizes highly scalable parallel applications for classification and sequence alignment. Using Extreme Science and Engineering Discovery Environment supercomputers, the workflow processed 1,200,000 newly sequenced bacterial proteins. With the rapid expansion of the protein sequence universe, the proposed workflow will enable scientists to annotate big genome data.
Optimizing high performance computing workflow for protein functional annotation

PubMed Central

Stanberry, Larissa; Rekepalli, Bhanu; Liu, Yuan; Giblock, Paul; Higdon, Roger; Montague, Elizabeth; Broomall, William; Kolker, Natali; Kolker, Eugene

2014-01-01

Functional annotation of newly sequenced genomes is one of the major challenges in modern biology. With modern sequencing technologies, the protein sequence universe is rapidly expanding. Newly sequenced bacterial genomes alone contain over 7.5 million proteins. The rate of data generation has far surpassed that of protein annotation. The volume of protein data makes manual curation infeasible, whereas a high compute cost limits the utility of existing automated approaches. In this work, we present an improved and optmized automated workflow to enable large-scale protein annotation. The workflow uses high performance computing architectures and a low complexity classification algorithm to assign proteins into existing clusters of orthologous groups of proteins. On the basis of the Position-Specific Iterative Basic Local Alignment Search Tool the algorithm ensures at least 80% specificity and sensitivity of the resulting classifications. The workflow utilizes highly scalable parallel applications for classification and sequence alignment. Using Extreme Science and Engineering Discovery Environment supercomputers, the workflow processed 1,200,000 newly sequenced bacterial proteins. With the rapid expansion of the protein sequence universe, the proposed workflow will enable scientists to annotate big genome data. PMID:25313296
Reduced genetic distance and high replication levels increase the RNA recombination rate of hepatitis delta virus.

PubMed

Lin, Chia-Chi; Yang, Zhi-Wei; Iang, Shan-Bei; Chao, Mei

2015-01-02

Hepatitis delta virus (HDV) replication is carried out by host RNA polymerases. Since homologous inter-genotypic RNA recombination is known to occur in HDV, possibly via a replication-dependent process, we hypothesized that the degree of sequence homology and the replication level should be related to the recombination frequency in cells co-expressing two HDV sequences. To confirm this, we separately co-transfected cells with three different pairs of HDV genomic RNAs and analyzed the obtained recombinants by RT-PCR followed by restriction fragment length polymorphism and sequencing analyses. The sequence divergence between the clones ranged from 24% to less than 0.1%, and the difference in replication levels was as high as 100-fold. As expected, significant differences were observed in the recombination frequencies, which ranged from 0.5% to 47.5%. Furthermore, varying the relative amounts of parental RNA altered the dominant recombinant species produced, suggesting that template switching occurs frequently during the synthesis of genomic HDV RNA. Taken together, these data suggest that during the host RNA polymerase-driven RNA recombination of HDV, both inter- and intra-genotypic recombination events are important in shaping the genetic diversity of HDV. Copyright © 2014 Elsevier B.V. All rights reserved.

Molecular Characterization of a Novel Species of Capillovirus from Japanese Apricot (Prunus mume)

PubMed Central

Faure, Chantal; Theil, Sébastien; Candresse, Thierry

2018-01-01

With the increased use of high-throughput sequencing methods, new viruses infecting Prunus spp. are being discovered and characterized, especially in the family Betaflexiviridae. Double-stranded RNAs from symptomatic leaves of a Japanese apricot (Prunus mume) tree from Japan were purified and analyzed by Illumina sequencing. Blast comparisons of reconstructed contigs showed that the P. mume sample was infected by a putative novel virus with homologies to Cherry virus A (CVA) and to the newly described Currant virus A (CuVA), both members of genus Capillovirus. Completion of the genome showed the new agent to have a genomic organization typical of capilloviruses, with two overlapping open reading frames encoding a large replication-associated protein fused to the coat protein (CP), and a putative movement protein (MP). This virus shares only, respectively, 63.2% and 62.7% CP amino acid identity with the most closely related viruses, CVA and CuVA. Considering the species demarcation criteria in the family and phylogenetic analyses, this virus should be considered as representing a new viral species in the genus Capillovirus, for which the name of Mume virus A is proposed. PMID:29570605
In vitro resolution of the dimer bridge of the minute virus of mice (MVM) genome supports the modified rolling hairpin model for MVM replication.

PubMed

Liu, Q; Yong, C B; Astell, C R

1994-06-01

Previous characterization of the terminal sequences of the minute virus of mice (MVM) genome demonstrated that the right hand palindrome contains two sequences, each the inverted complement of the other. However, the left hand palindrome was shown to exist as a unique sequence [Astell et al., J. Virol. 54: 179-185 (1985)]. The modified rolling hairpin (MRH) model for MVM replication provided an explanation of how the right hand palindrome could undergo hairpin transfer to generate two sequences, while the left end palindrome within the dimer bridge could undergo asymmetric resolution and retain the unique left end sequence. This report describes in vitro resolution of the wild-type dimer bridge sequence of MVM using recombinant (baculovirus) expressed NS-1 and a replication extract from LA9 cells. The resolution products are consistent with those predicted by the MRH model, providing support for this replication mechanism. In addition, mutant dimer bridge clones were constructed and used in the resolution assay. The mutant structures included removal of the asymmetry in the hairpin stem, inversion of the sequence at the initiating nick site, and a 2-bp deletion within one stem of the dimer bridge. In all cases, the mutant dimer bridge structures are resolved; however, the resolution pattern observed with the mutant dimer bridge compared with the wild-type dimer bridge is shifted toward symmetrical resolution. These results suggest that sequences within the left hand hairpin (and hence dimer bridge sequence) are responsible for asymmetric resolution and conservation of the unique sequence within the left hand palindrome of the MVM genome.
Emerging players in the initiation of eukaryotic DNA replication

PubMed Central

2012-01-01

Faithful duplication of the genome in eukaryotes requires ordered assembly of a multi-protein complex called the pre-replicative complex (pre-RC) prior to S phase; transition to the pre-initiation complex (pre-IC) at the beginning of DNA replication; coordinated progression of the replisome during S phase; and well-controlled regulation of replication licensing to prevent re-replication. These events are achieved by the formation of distinct protein complexes that form in a cell cycle-dependent manner. Several components of the pre-RC and pre-IC are highly conserved across all examined eukaryotic species. Many of these proteins, in addition to their bona fide roles in DNA replication are also required for other cell cycle events including heterochromatin organization, chromosome segregation and centrosome biology. As the complexity of the genome increases dramatically from yeast to human, additional proteins have been identified in higher eukaryotes that dictate replication initiation, progression and licensing. In this review, we discuss the newly discovered components and their roles in cell cycle progression. PMID:23075259
DNA Sequences Proximal to Human Mitochondrial DNA Deletion Breakpoints Prevalent in Human Disease Form G-quadruplexes, a Class of DNA Structures Inefficiently Unwound by the Mitochondrial Replicative Twinkle Helicase*

PubMed Central

Bharti, Sanjay Kumar; Sommers, Joshua A.; Zhou, Jun; Kaplan, Daniel L.; Spelbrink, Johannes N.; Mergny, Jean-Louis; Brosh, Robert M.

2014-01-01

Mitochondrial DNA deletions are prominent in human genetic disorders, cancer, and aging. It is thought that stalling of the mitochondrial replication machinery during DNA synthesis is a prominent source of mitochondrial genome instability; however, the precise molecular determinants of defective mitochondrial replication are not well understood. In this work, we performed a computational analysis of the human mitochondrial genome using the “Pattern Finder” G-quadruplex (G4) predictor algorithm to assess whether G4-forming sequences reside in close proximity (within 20 base pairs) to known mitochondrial DNA deletion breakpoints. We then used this information to map G4P sequences with deletions characteristic of representative mitochondrial genetic disorders and also those identified in various cancers and aging. Circular dichroism and UV spectral analysis demonstrated that mitochondrial G-rich sequences near deletion breakpoints prevalent in human disease form G-quadruplex DNA structures. A biochemical analysis of purified recombinant human Twinkle protein (gene product of c10orf2) showed that the mitochondrial replicative helicase inefficiently unwinds well characterized intermolecular and intramolecular G-quadruplex DNA substrates, as well as a unimolecular G4 substrate derived from a mitochondrial sequence that nests a deletion breakpoint described in human renal cell carcinoma. Although G4 has been implicated in the initiation of mitochondrial DNA replication, our current findings suggest that mitochondrial G-quadruplexes are also likely to be a source of instability for the mitochondrial genome by perturbing the normal progression of the mitochondrial replication machinery, including DNA unwinding by Twinkle helicase. PMID:25193669
GC-Rich DNA Elements Enable Replication Origin Activity in the Methylotrophic Yeast Pichia pastoris

PubMed Central

Liachko, Ivan; Youngblood, Rachel A.; Tsui, Kyle; Bubb, Kerry L.; Queitsch, Christine; Raghuraman, M. K.; Nislow, Corey; Brewer, Bonita J.; Dunham, Maitreya J.

2014-01-01

The well-studied DNA replication origins of the model budding and fission yeasts are A/T-rich elements. However, unlike their yeast counterparts, both plant and metazoan origins are G/C-rich and are associated with transcription start sites. Here we show that an industrially important methylotrophic budding yeast, Pichia pastoris, simultaneously employs at least two types of replication origins—a G/C-rich type associated with transcription start sites and an A/T-rich type more reminiscent of typical budding and fission yeast origins. We used a suite of massively parallel sequencing tools to map and dissect P. pastoris origins comprehensively, to measure their replication dynamics, and to assay the global positioning of nucleosomes across the genome. Our results suggest that some functional overlap exists between promoter sequences and G/C-rich replication origins in P. pastoris and imply an evolutionary bifurcation of the modes of replication initiation. PMID:24603708
GC-rich DNA elements enable replication origin activity in the methylotrophic yeast Pichia pastoris.

PubMed

Liachko, Ivan; Youngblood, Rachel A; Tsui, Kyle; Bubb, Kerry L; Queitsch, Christine; Raghuraman, M K; Nislow, Corey; Brewer, Bonita J; Dunham, Maitreya J

2014-03-01

The well-studied DNA replication origins of the model budding and fission yeasts are A/T-rich elements. However, unlike their yeast counterparts, both plant and metazoan origins are G/C-rich and are associated with transcription start sites. Here we show that an industrially important methylotrophic budding yeast, Pichia pastoris, simultaneously employs at least two types of replication origins--a G/C-rich type associated with transcription start sites and an A/T-rich type more reminiscent of typical budding and fission yeast origins. We used a suite of massively parallel sequencing tools to map and dissect P. pastoris origins comprehensively, to measure their replication dynamics, and to assay the global positioning of nucleosomes across the genome. Our results suggest that some functional overlap exists between promoter sequences and G/C-rich replication origins in P. pastoris and imply an evolutionary bifurcation of the modes of replication initiation.
Sequence Analysis of the Cryptic Plasmid pMG101 from Rhodopseudomonas palustris and Construction of Stable Cloning Vectors

PubMed Central

Inui, Masayuki; Roh, Jung Hyeob; Zahn, Kenneth; Yukawa, Hideaki

2000-01-01

A 15-kb cryptic plasmid was obtained from a natural isolate of Rhodopseudomonas palustris. The plasmid, designated pMG101, was able to replicate in R. palustris and in closely related strains of Bradyrhizobium japonicum and phototrophic Bradyrhizobium species. However, it was unable to replicate in the purple nonsulfur bacterium Rhodobacter sphaeroides and in Rhizobium species. The replication region of pMG101 was localized to a 3.0-kb SalI-XhoI fragment, and this fragment was stably maintained in R. palustris for over 100 generations in the absence of selection. The complete nucleotide sequence of this fragment revealed two open reading frames (ORFs), ORF1 and ORF2. The deduced amino acid sequence of ORF1 is similar to sequences of Par proteins, which mediate plasmid stability from certain plasmids, while ORF2 was identified as a putative rep gene, coding for an initiator of plasmid replication, based on homology with the Rep proteins of several other plasmids. The function of these sequences was studied by deletion mapping and gene disruptions of ORF1 and ORF2. pMG101-based Escherichia coli-R. palustris shuttle cloning vectors pMG103 and pMG105 were constructed and were stably maintained in R. palustris growing under nonselective conditions. The ability of plasmid pMG101 to replicate in R. palustris and its close phylogenetic relatives should enable broad application of these vectors within this group of α-proteobacteria. PMID:10618203
Characterizing the replicability of cell types defined by single cell RNA-sequencing data using MetaNeighbor.

PubMed

Crow, Megan; Paul, Anirban; Ballouz, Sara; Huang, Z Josh; Gillis, Jesse

2018-02-28

Single-cell RNA-sequencing (scRNA-seq) technology provides a new avenue to discover and characterize cell types; however, the experiment-specific technical biases and analytic variability inherent to current pipelines may undermine its replicability. Meta-analysis is further hampered by the use of ad hoc naming conventions. Here we demonstrate our replication framework, MetaNeighbor, that quantifies the degree to which cell types replicate across datasets, and enables rapid identification of clusters with high similarity. We first measure the replicability of neuronal identity, comparing results across eight technically and biologically diverse datasets to define best practices for more complex assessments. We then apply this to novel interneuron subtypes, finding that 24/45 subtypes have evidence of replication, which enables the identification of robust candidate marker genes. Across tasks we find that large sets of variably expressed genes can identify replicable cell types with high accuracy, suggesting a general route forward for large-scale evaluation of scRNA-seq data.
Genes That Escape X-Inactivation in Humans Have High Intraspecific Variability in Expression, Are Associated with Mental Impairment but Are Not Slow Evolving

PubMed Central

Zhang, Yuchao; Castillo-Morales, Atahualpa; Jiang, Min; Zhu, Yufei; Hu, Landian; Urrutia, Araxi O.; Kong, Xiangyin; Hurst, Laurence D.

2013-01-01

In female mammals most X-linked genes are subject to X-inactivation. However, in humans some X-linked genes escape silencing, these escapees being candidates for the phenotypic aberrations seen in polyX karyotypes. These escape genes have been reported to be under stronger purifying selection than other X-linked genes. Although it is known that escape from X-inactivation is much more common in humans than in mice, systematic assays of escape in humans have to date employed only interspecies somatic cell hybrids. Here we provide the first systematic next-generation sequencing analysis of escape in a human cell line. We analyzed RNA and genotype sequencing data obtained from B lymphocyte cell lines derived from Europeans (CEU) and Yorubans (YRI). By replicated detection of heterozygosis in the transcriptome, we identified 114 escaping genes, including 76 not previously known to be escapees. The newly described escape genes cluster on the X chromosome in the same chromosomal regions as the previously known escapees. There is an excess of escaping genes associated with mental retardation, consistent with this being a common phenotype of polyX phenotypes. We find both differences between populations and between individuals in the propensity to escape. Indeed, we provide the first evidence for there being both hyper- and hypo-escapee females in the human population, consistent with the highly variable phenotypic presentation of polyX karyotypes. Considering also prior data, we reclassify genes as being always, never, and sometimes escape genes. We fail to replicate the prior claim that genes that escape X-inactivation are under stronger purifying selection than others. PMID:24023392
DOE Office of Scientific and Technical Information (OSTI.GOV)

Tzeng, W.-P.; Frey, Teryl K.

The ratio of the subgenomic (SG) to genome RNA synthesized by rubella virus (RUB) replicons expressing the green fluorescent protein reporter gene (RUBrep/GFP) is substantially higher than the ratio of these species synthesized by RUB (4.3 for RUBrep/GFP vs. 1.3-1.4 for RUB). It was hypothesized that this modulation of the viral RNA synthesis was by one of the virus structural protein genes and it was found that introduction of the capsid (C) protein gene into the replicons as an in-frame fusion with GFP resulted in an increase of genomic RNA production (reducing the SG/genome RNA ratio), confirming the hypothesis andmore » showing that the C gene was the moiety responsible for the modulation effect. The N-terminal one-third of the C gene was required for the effect of be exhibited. A similar phenomenon was not observed with the replicons of Sindbis virus, a related Alphavirus. Interestingly, modulation was not observed when RUBrep/GFP was co-transfected with either other RUBrep or plasmid constructs expressing the C gene, demonstrating that modulation could occur only when the C gene was provided in cis. Mutations that prevented translation of the C protein failed to modulate RNA synthesis, indicating that the C protein was the moiety responsible for modulation; consistent with this conclusion, modulation of RNA synthesis was maintained when synonymous codon mutations were introduced at the 5' end of the C gene that changed the C gene sequence without altering the amino acid sequence of the C protein. These results indicate that C protein translated in proximity of viral replication complexes, possibly from newly synthesized SG RNA, participate in regulating the replication of viral RNA.« less
The barley EST DNA Replication and Repair Database (bEST-DRRD) as a tool for the identification of the genes involved in DNA replication and repair.

PubMed

Gruszka, Damian; Marzec, Marek; Szarejko, Iwona

2012-06-14

The high level of conservation of genes that regulate DNA replication and repair indicates that they may serve as a source of information on the origin and evolution of the species and makes them a reliable system for the identification of cross-species homologs. Studies that had been conducted to date shed light on the processes of DNA replication and repair in bacteria, yeast and mammals. However, there is still much to be learned about the process of DNA damage repair in plants. These studies, which were conducted mainly using bioinformatics tools, enabled the list of genes that participate in various pathways of DNA repair in Arabidopsis thaliana (L.) Heynh to be outlined; however, information regarding these mechanisms in crop plants is still very limited. A similar, functional approach is particularly difficult for a species whose complete genomic sequences are still unavailable. One of the solutions is to apply ESTs (Expressed Sequence Tags) as the basis for gene identification. For the construction of the barley EST DNA Replication and Repair Database (bEST-DRRD), presented here, the Arabidopsis nucleotide and protein sequences involved in DNA replication and repair were used to browse for and retrieve the deposited sequences, derived from four barley (Hordeum vulgare L.) sequence databases, including the "Barley Genome version 0.05" database (encompassing ca. 90% of barley coding sequences) and from two databases covering the complete genomes of two monocot models: Oryza sativa L. and Brachypodium distachyon L. in order to identify homologous genes. Sequences of the categorised Arabidopsis queries are used for browsing the repositories, which are located on the ViroBLAST platform. The bEST-DRRD is currently used in our project during the identification and validation of the barley genes involved in DNA repair. The presented database provides information about the Arabidopsis genes involved in DNA replication and repair, their expression patterns and models of protein interactions. It was designed and established to provide an open-access tool for the identification of monocot homologs of known Arabidopsis genes that are responsible for DNA-related processes. The barley genes identified in the project are currently being analysed to validate their function.
DNA polymerases eta and kappa exchange with the polymerase delta holoenzyme to complete common fragile site synthesis.

PubMed

Barnes, Ryan P; Hile, Suzanne E; Lee, Marietta Y; Eckert, Kristin A

2017-09-01

Common fragile sites (CFSs) are inherently unstable genomic loci that are recurrently altered in human tumor cells. Despite their instability, CFS are ubiquitous throughout the human genome and associated with large tumor suppressor genes or oncogenes. CFSs are enriched with repetitive DNA sequences, one feature postulated to explain why these loci are inherently difficult to replicate, and sensitive to replication stress. We have shown that specialized DNA polymerases (Pols) η and κ replicate CFS-derived sequences more efficiently than the replicative Pol δ. However, we lacked an understanding of how these enzymes cooperate to ensure efficient CFS replication. Here, we designed a model of lagging strand replication with RFC loaded PCNA that allows for maximal activity of the four-subunit human Pol δ holoenzyme, Pol η, and Pol κ in polymerase mixing assays. We discovered that Pol η and κ are both able to exchange with Pol δ stalled at repetitive CFS sequences, enhancing Normalized Replication Efficiency. We used this model to test the impact of PCNA mono-ubiquitination on polymerase exchange, and found no change in polymerase cooperativity in CFS replication compared with unmodified PCNA. Finally, we modeled replication stress in vitro using aphidicolin and found that Pol δ holoenzyme synthesis was significantly inhibited in a dose-dependent manner, preventing any replication past the CFS. Importantly, Pol η and κ were still proficient in rescuing this stalled Pol δ synthesis, which may explain, in part, the CFS instability phenotype of aphidicolin-treated Pol η and Pol κ-deficient cells. In total, our data support a model wherein Pol δ stalling at CFSs allows for free exchange with a specialized polymerase that is not driven by PCNA. Copyright © 2017 Elsevier B.V. All rights reserved.
IsomiR expression profiles in human lymphoblastoid cell lines exhibit population and gender dependencies

PubMed Central

Loher, Phillipe; Londin, Eric R.; Rigoutsos, Isidore

2014-01-01

For many years it was believed that each mature microRNA (miRNA) existed as a single entity with fixed endpoints and a ‘static’ and unchangeable primary sequence. However, recent evidence suggests that mature miRNAs are more ‘dynamic’ and that each miRNA precursor arm gives rise to multiple isoforms, the isomiRs. Here we report on our identification of numerous and abundant isomiRs in the lymphoblastoid cell lines (LCLs) of 452 men and women from five different population groups. Unexpectedly, we find that these isomiRs exhibit an expression profile that is population-dependent and gender-dependent. This is important as it indicates that the LCLs of each gender/population combination have their own unique collection of mature miRNA transcripts. Moreover, each identified isomiR has its own characteristic abundance that remains consistent across biological replicates indicating that these are not degradation products. The primary sequences of identified isomiRs differ from the known miRBase miRNA either at their 5´-endpoint (leads to a different ‘seed’ sequence and suggests a different targetome), their 3´-endpoint, or both simultaneously. Our analysis of Argonaute PAR-CLIP data from LCLs supports the association of many of these newly identified isomiRs with the Argonaute silencing complex and thus their functional roles through participation in the RNA interference pathway. PMID:25229428
IsomiR expression profiles in human lymphoblastoid cell lines exhibit population and gender dependencies.

PubMed

Loher, Phillipe; Londin, Eric R; Rigoutsos, Isidore

2014-09-30

For many years it was believed that each mature microRNA (miRNA) existed as a single entity with fixed endpoints and a 'static' and unchangeable primary sequence. However, recent evidence suggests that mature miRNAs are more 'dynamic' and that each miRNA precursor arm gives rise to multiple isoforms, the isomiRs. Here we report on our identification of numerous and abundant isomiRs in the lymphoblastoid cell lines (LCLs) of 452 men and women from five different population groups. Unexpectedly, we find that these isomiRs exhibit an expression profile that is population-dependent and gender-dependent. This is important as it indicates that the LCLs of each gender/population combination have their own unique collection of mature miRNA transcripts. Moreover, each identified isomiR has its own characteristic abundance that remains consistent across biological replicates indicating that these are not degradation products. The primary sequences of identified isomiRs differ from the known miRBase miRNA either at their 5´-endpoint (leads to a different 'seed' sequence and suggests a different targetome), their 3´-endpoint, or both simultaneously. Our analysis of Argonaute PAR-CLIP data from LCLs supports the association of many of these newly identified isomiRs with the Argonaute silencing complex and thus their functional roles through participation in the RNA interference pathway.
DNA adenine methylation is required to replicate both Vibrio cholerae chromosomes once per cell cycle.

PubMed

Demarre, Gaëlle; Chattoraj, Dhruba K

2010-05-06

DNA adenine methylation is widely used to control many DNA transactions, including replication. In Escherichia coli, methylation serves to silence newly synthesized (hemimethylated) sister origins. SeqA, a protein that binds to hemimethylated DNA, mediates the silencing, and this is necessary to restrict replication to once per cell cycle. The methylation, however, is not essential for replication initiation per se but appeared so when the origins (oriI and oriII) of the two Vibrio cholerae chromosomes were used to drive plasmid replication in E. coli. Here we show that, as in the case of E. coli, methylation is not essential for oriI when it drives chromosomal replication and is needed for once-per-cell-cycle replication in a SeqA-dependent fashion. We found that oriII also needs SeqA for once-per-cell-cycle replication and, additionally, full methylation for efficient initiator binding. The requirement for initiator binding might suffice to make methylation an essential function in V. cholerae. The structure of oriII suggests that it originated from a plasmid, but unlike plasmids, oriII makes use of methylation for once-per-cell-cycle replication, the norm for chromosomal but not plasmid replication.
Identification of a high-efficiency baculovirus DNA replication origin that functions in insect and mammalian cells.

PubMed

Wu, Yueh-Lung; Wu, Carol-P; Huang, Yu-Hui; Huang, Sheng-Ping; Lo, Huei-Ru; Chang, Hao-Shuo; Lin, Pi-Hsiu; Wu, Ming-Cheng; Chang, Chia-Jung; Chao, Yu-Chan

2014-11-01

The p143 gene from Autographa californica multinucleocapsid nucleopolyhedrovirus (AcMNPV) has been found to increase the expression of luciferase, which is driven by the polyhedrin gene promoter, in a plasmid with virus coinfection. Further study indicated that this is due to the presence of a replication origin (ori) in the coding region of this gene. Transient DNA replication assays showed that a specific fragment of the p143 coding sequence, p143-3, underwent virus-dependent DNA replication in Spodoptera frugiperda IPLB-Sf-21 (Sf-21) cells. Deletion analysis of the p143-3 fragment showed that subfragment p143-3.2a contained the essential sequence of this putative ori. Sequence analysis of this region revealed a unique distribution of imperfect palindromes with high AT contents. No sequence homology or similarity between p143-3.2a and any other known ori was detected, suggesting that it is a novel baculovirus ori. Further study showed that the p143-3.2a ori can replicate more efficiently in infected Sf-21 cells than baculovirus homologous regions (hrs), the major baculovirus ori, or non-hr oris during virus replication. Previously, hr on its own was unable to replicate in mammalian cells, and for mammalian viral oris, viral proteins are generally required for their proper replication in host cells. However, the p143-3.2a ori was, surprisingly, found to function as an efficient ori in mammalian cells without the need for any viral proteins. We conclude that p143 contains a unique sequence that can function as an ori to enhance gene expression in not only insect cells but also mammalian cells. Baculovirus DNA replication relies on both hr and non-hr oris; however, so far very little is known about the latter oris. Here we have identified a new non-hr ori, the p143 ori, which resides in the coding region of p143. By developing a novel DNA replication-enhanced reporter system, we have identified and located the core region required for the p143 ori. This ori contains a large number of imperfect inverted repeats and is the most active ori in the viral genome during virus infection in insect cells. We also found that it is a unique ori that can replicate in mammalian cells without the assistance of baculovirus gene products. The identification of this ori should contribute to a better understanding of baculovirus DNA replication. Also, this ori is very useful in assisting with gene expression in mammalian cells. Copyright © 2014, American Society for Microbiology. All Rights Reserved.
Leafhopper viral pathogens

USDA-ARS?s Scientific Manuscript database

Four newly discovered viral pathogens in leafhopper vectors of Pierce’s disease of grapes, have been shown to replicate in sharpshooter leafhoppers; the glassy-winged sharpshooter, GWSS, Homalodisca vitripennis, and Oncometopia nigricans (Hemiptera: Cicadellidae). The viruses were classified as memb...
Chromosomal context and replication properties of ARS plasmids in Schizosaccharomyces pombe.

PubMed

Pratihar, Aditya S; Tripathi, Vishnu P; Yadav, Mukesh P; Dubey, Dharani D

2015-12-01

Short, specific DNA sequences called as Autonomously Replicating Sequence (ARS) elements function as plasmid as well as chromosomal replication origins in yeasts. As compared to ARSs, different chromosomal origins vary greatly in their efficiency and timing of replication probably due to their wider chromosomal context. The two Schizosaccharomyces pombe ARS elements, ars727 and ars2004, represent two extremities in their chromosomal origin activity - ars727 is inactive and late replicating, while ars2004 is a highly active, early-firing origin. To determine the effect of chromosomal context on the activity of these ARS elements, we have cloned them with their extended chromosomal context as well as in the context of each other in both orientations and analysed their replication efficiency by ARS and plasmid stability assays. We found that these ARS elements retain their origin activity in their extended/altered context. However, deletion of a 133-bp region of the previously reported ars727- associated late replication enforcing element (LRE) caused advancement in replication timing of the resulting plasmid. These results confirm the role of LRE in directing plasmid replication timing and suggest that the plasmid origin efficiency of ars2004 or ars727 remains unaltered by the extended chromosomal context.
Regions flanking ori sequences affect the replication efficiency of the mitochondrial genome of ori+ petite mutants from yeast.

PubMed

Rayko, E; Goursot, R; Cherif-Zahar, B; Melis, R; Bernardi, G

1988-03-31

The mitochondrial genomes of progenies from 26 crosses between 17 cytoplasmic, spontaneous, suppressive, ori+ petite mutants of Saccharomyces cerevisiae have been studied by electrophoresis of restriction fragments. Only parental genomes (or occasionally, genomes derived from them by secondary excisions) were found in the progenies of the almost 500 diploids investigated; no evidence for illegitimate, site-specific mitochondrial recombination was detected. One of the parental genomes was always found to be predominate over the other one, although to different extents in different crosses. This predominance appears to be due to a higher replication efficiency, which is correlated with a greater density of ori sequences on the mitochondrial genome (and with a shorter repeat unit size of the latter). Exceptions to the 'repeat-unit-size rule' were found, however, even when the parental mitochondrial genomes carried the same ori sequence. This indicates that noncoding, intergenic sequences outside ori sequences also play a role in modulating replication efficiency. Since in different petites such sequences differ in primary structure, size, and position relative to ori sequences, this modulation is likely to take place through an indirect effect on DNA and nucleoid structure.
Crystallization and preliminary X-ray diffraction analysis of the Bacillus subtilis replication termination protein in complex with the 37-base-pair TerI-binding site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vivian, J. P.; Porter, C.; Wilce, J. A.

2006-11-01

A preparation of replication terminator protein (RTP) of B. subtilis and a 37-base-pair TerI sequence (comprising two binding sites for RTP) has been purified and crystallized. The replication terminator protein (RTP) of Bacillus subtilis binds to specific DNA sequences that halt the progression of the replisome in a polar manner. These terminator complexes flank a defined region of the chromosome into which they allow replication forks to enter but not exit. Forcing the fusion of replication forks in a specific zone is thought to allow the coordination of post-replicative processes. The functional terminator complex comprises two homodimers each of 29more » kDa bound to overlapping binding sites. A preparation of RTP and a 37-base-pair TerI sequence (comprising two binding sites for RTP) has been purified and crystallized. A data set to 3.9 Å resolution with 97.0% completeness and an R{sub sym} of 12% was collected from a single flash-cooled crystal using synchrotron radiation. The diffraction data are consistent with space group P622, with unit-cell parameters a = b = 118.8, c = 142.6 Å.« less

Unprecedented large inverted repeats at the replication terminus of circular bacterial chromosomes suggest a novel mode of chromosome rescue

PubMed Central

El Kafsi, Hela; Loux, Valentin; Mariadassou, Mahendra; Blin, Camille; Chiapello, Hélène; Abraham, Anne-Laure; Maguin, Emmanuelle; van de Guchte, Maarten

2017-01-01

The first Lactobacillus delbrueckii ssp. bulgaricus genome sequence revealed the presence of a very large inverted repeat (IR), a DNA sequence arrangement which thus far seemed inconceivable in a non-manipulated circular bacterial chromosome, at the replication terminus. This intriguing observation prompted us to investigate if similar IRs could be found in other bacteria. IRs with sizes varying from 38 to 76 kbp were found at the replication terminus of all 5 L. delbrueckii ssp. bulgaricus chromosomes analysed, but in none of 1373 other chromosomes. They represent the first naturally occurring very large IRs detected in circular bacterial genomes. A comparison of the L. bulgaricus replication terminus regions and the corresponding regions without IR in 5 L. delbrueckii ssp. lactis genomes leads us to propose a model for the formation and evolution of the IRs. The DNA sequence data are consistent with a novel model of chromosome rescue after premature replication termination or irreversible chromosome damage near the replication terminus, involving mechanisms analogous to those proposed in the formation of very large IRs in human cancer cells. We postulate that the L. delbrueckii ssp. bulgaricus-specific IRs in different strains derive from a single ancestral IR of at least 93 kbp. PMID:28281695
DNA-PKcs phosphorylates hnRNP-A1 to facilitate the RPA-to-POT1 switch and telomere capping after replication.

PubMed

Sui, Jiangdong; Lin, Yu-Fen; Xu, Kangling; Lee, Kyung-Jong; Wang, Dong; Chen, Benjamin P C

2015-07-13

The heterogeneous nuclear ribonucleoprotein A1 (hnRNP-A1) has been implicated in telomere protection and telomerase activation. Recent evidence has further demonstrated that hnRNP-A1 plays a crucial role in maintaining newly replicated telomeric 3' overhangs and facilitating the switch from replication protein A (RPA) to protection of telomeres 1 (POT1). The role of hnRNP-A1 in telomere protection also involves DNA-dependent protein kinase catalytic subunit (DNA-PKcs), although the detailed regulation mechanism has not been clear. Here we report that hnRNP-A1 is phosphorylated by DNA-PKcs during the G2 and M phases and that DNA-PK-dependent hnRNP-A1 phosphorylation promotes the RPA-to-POT1 switch on telomeric single-stranded 3' overhangs. Consequently, in cells lacking hnRNP-A1 or DNA-PKcs-dependent hnRNP-A1 phosphorylation, impairment of the RPA-to-POT1 switch results in DNA damage response at telomeres during mitosis as well as induction of fragile telomeres. Taken together, our results indicate that DNA-PKcs-dependent hnRNP-A1 phosphorylation is critical for capping of the newly replicated telomeres and prevention of telomeric aberrations. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.
Method for rapid base sequencing in DNA and RNA with two base labeling

DOEpatents

Jett, J.H.; Keller, R.A.; Martin, J.C.; Posner, R.G.; Marrone, B.L.; Hammond, M.L.; Simpson, D.J.

1995-04-11

A method is described for rapid-base sequencing in DNA and RNA with two-base labeling and employing fluorescent detection of single molecules at two wavelengths. Bases modified to accept fluorescent labels are used to replicate a single DNA or RNA strand to be sequenced. The bases are then sequentially cleaved from the replicated strand, excited with a chosen spectrum of electromagnetic radiation, and the fluorescence from individual, tagged bases detected in the order of cleavage from the strand. 4 figures.
Method for rapid base sequencing in DNA and RNA with two base labeling

DOEpatents

Jett, James H.; Keller, Richard A.; Martin, John C.; Posner, Richard G.; Marrone, Babetta L.; Hammond, Mark L.; Simpson, Daniel J.

1995-01-01

Method for rapid-base sequencing in DNA and RNA with two-base labeling and employing fluorescent detection of single molecules at two wavelengths. Bases modified to accept fluorescent labels are used to replicate a single DNA or RNA strand to be sequenced. The bases are then sequentially cleaved from the replicated strand, excited with a chosen spectrum of electromagnetic radiation, and the fluorescence from individual, tagged bases detected in the order of cleavage from the strand.
Infection of Mouse Macrophages by Seasonal Influenza Viruses Can Be Restricted at the Level of Virus Entry and at a Late Stage in the Virus Life Cycle

PubMed Central

Londrigan, Sarah L.; Short, Kirsty R.; Ma, Joel; Gillespie, Leah; Rockman, Steven P.; Brooks, Andrew G.

2015-01-01

ABSTRACT Airway epithelial cells are susceptible to infection with seasonal influenza A viruses (IAV), resulting in productive virus replication and release. Macrophages (MΦ) are also permissive to IAV infection; however, virus replication is abortive. Currently, it is unclear how productive infection of MΦ is impaired or the extent to which seasonal IAV replicate in MΦ. Herein, we compared mouse MΦ and epithelial cells for their ability to support genomic replication and transcription, synthesis of viral proteins, assembly of virions, and release of infectious progeny following exposure to genetically defined IAV. We confirm that seasonal IAV differ in their ability to utilize cell surface receptors for infectious entry and that this represents one level of virus restriction. Following virus entry, we demonstrate synthesis of all eight segments of genomic viral RNA (vRNA) and mRNA, as well as seven distinct IAV proteins, in IAV-infected mouse MΦ. Although newly synthesized hemagglutinin (HA) and neuraminidase (NA) glycoproteins are incorporated into the plasma membrane and expressed at the cell surface, electron microscopy confirmed that virus assembly was defective in IAV-infected MΦ, defining a second level of restriction late in the virus life cycle. IMPORTANCE Seasonal influenza A viruses (IAV) and highly pathogenic avian influenza viruses (HPAI) infect macrophages, but only HPAI replicate productively in these cells. Herein, we demonstrate that impaired virus uptake into macrophages represents one level of restriction limiting infection by seasonal IAV. Following uptake, seasonal IAV do not complete productive replication in macrophages, representing a second level of restriction. Using murine macrophages, we demonstrate that productive infection is blocked late in the virus life cycle, such that virus assembly is defective and newly synthesized virions are not released. These studies represent an important step toward identifying host-encoded factors that block replication of seasonal IAV, but not HPAI, in macrophages. PMID:26423941
Infection of Mouse Macrophages by Seasonal Influenza Viruses Can Be Restricted at the Level of Virus Entry and at a Late Stage in the Virus Life Cycle.

PubMed

Londrigan, Sarah L; Short, Kirsty R; Ma, Joel; Gillespie, Leah; Rockman, Steven P; Brooks, Andrew G; Reading, Patrick C

2015-12-01

Airway epithelial cells are susceptible to infection with seasonal influenza A viruses (IAV), resulting in productive virus replication and release. Macrophages (MΦ) are also permissive to IAV infection; however, virus replication is abortive. Currently, it is unclear how productive infection of MΦ is impaired or the extent to which seasonal IAV replicate in MΦ. Herein, we compared mouse MΦ and epithelial cells for their ability to support genomic replication and transcription, synthesis of viral proteins, assembly of virions, and release of infectious progeny following exposure to genetically defined IAV. We confirm that seasonal IAV differ in their ability to utilize cell surface receptors for infectious entry and that this represents one level of virus restriction. Following virus entry, we demonstrate synthesis of all eight segments of genomic viral RNA (vRNA) and mRNA, as well as seven distinct IAV proteins, in IAV-infected mouse MΦ. Although newly synthesized hemagglutinin (HA) and neuraminidase (NA) glycoproteins are incorporated into the plasma membrane and expressed at the cell surface, electron microscopy confirmed that virus assembly was defective in IAV-infected MΦ, defining a second level of restriction late in the virus life cycle. Seasonal influenza A viruses (IAV) and highly pathogenic avian influenza viruses (HPAI) infect macrophages, but only HPAI replicate productively in these cells. Herein, we demonstrate that impaired virus uptake into macrophages represents one level of restriction limiting infection by seasonal IAV. Following uptake, seasonal IAV do not complete productive replication in macrophages, representing a second level of restriction. Using murine macrophages, we demonstrate that productive infection is blocked late in the virus life cycle, such that virus assembly is defective and newly synthesized virions are not released. These studies represent an important step toward identifying host-encoded factors that block replication of seasonal IAV, but not HPAI, in macrophages. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
A SHORT SEQUENCE IMMEDIATELY UPSTREAM OF THE INTERNAL REPEAT ELEMENTS IS CRITICAL FOR KSHV LANA MEDIATED DNA REPLICATION AND IMPACTS EPISOME PERSISTENCE

PubMed Central

León Vázquez, Erika De; Juillard, Franceline; Rosner, Bernard; Kaye, Kenneth M.

2013-01-01

Kaposi’s sarcoma-associated herpesvirus LANA (1162 residues) mediates episomal persistence of viral genomes during latency. LANA mediates viral DNA replication and segregates episomes to daughter nuclei. A 59 residue deletion immediately upstream of the internal repeat elements rendered LANA highly deficient for DNA replication and modestly deficient for the ability to segregate episomes, while smaller deletions did not. The 59 amino acid deletion reduced LANA episome persistence by ~14-fold, while sequentially smaller deletions resulted in ~3-fold, or no deficiency. Three distinct LANA regions reorganized heterochromatin, one of which contains the deleted sequence, but the deletion did not abolish LANA’s ability to alter chromatin. Therefore, this work identifies a short internal LANA sequence that is critical for DNA replication, has modest effects on episome segregation, and substantially impacts episome persistence; this region may exert its effects through an interacting host cell protein(s). PMID:24314665
Strong minor groove base conservation in sequence logos implies DNA distortion or base flipping during replication and transcription initiation | Center for Cancer Research

Cancer.gov

Dubbed "Tom's T" by Dhruba Chattoraj, the unusually conserved thymine at position +7 in bacteriophage P1 plasmid RepA DNA binding sites rises above repressor and acceptor sequence logos. The T appears to represent base flipping prior to helix opening in this DNA replication initation protein.
Nonenzymatic Role for WRN in Preserving Nascent DNA Strands after Replication Stress

DOE PAGES

Su, Fengtao; Mukherjee, Shibani; Yang, Yanyong; ...

2014-11-20

WRN, the protein defective in Werner syndrome (WS), is a multifunctional nuclease involved in DNA damage repair, replication, and genome stability maintenance. It was assumed that the nuclease activities of WRN were critical for these functions. Here, we report a nonenzymatic role for WRN in preserving nascent DNA strands following replication stress. We found that lack of WRN led to shortening of nascent DNA strands after replication stress. Furthermore, we discovered that the exonuclease activity of MRE11 was responsible for the shortening of newly replicated DNA in the absence of WRN. Mechanistically, the N-terminal FHA domain of NBS1 recruits WRNmore » to replication-associated DNA double-stranded breaks to stabilize Rad51 and to limit the nuclease activity of its C-terminal binding partner MRE11. Thus, this previously unrecognized nonenzymatic function of WRN in the stabilization of nascent DNA strands sheds light on the molecular reason for the origin of genome instability in WS individuals.« less
RPA Interacts with HIRA and Regulates H3.3 Deposition at Gene Regulatory Elements in Mammalian Cells.

PubMed

Zhang, Honglian; Gan, Haiyun; Wang, Zhiquan; Lee, Jeong-Heon; Zhou, Hui; Ordog, Tamas; Wold, Marc S; Ljungman, Mats; Zhang, Zhiguo

2017-01-19

The histone chaperone HIRA is involved in depositing histone variant H3.3 into distinct genic regions, including promoters, enhancers, and gene bodies. However, how HIRA deposits H3.3 to these regions remains elusive. Through a short hairpin RNA (shRNA) screening, we identified single-stranded DNA binding protein replication protein A (RPA) as a regulator of the deposition of newly synthesized H3.3 into chromatin. We show that RPA physically interacts with HIRA to form RPA-HIRA-H3.3 complexes, and it co-localizes with HIRA and H3.3 at gene promoters and enhancers. Depletion of RPA1, the largest subunit of the RPA complex, dramatically reduces both HIRA association with chromatin and the deposition of newly synthesized H3.3 at promoters and enhancers and leads to altered transcription at gene promoters. These results support a model whereby RPA, best known for its role in DNA replication and repair, recruits HIRA to promoters and enhancers and regulates deposition of newly synthesized H3.3 to these regulatory elements for gene regulation. Copyright © 2017 Elsevier Inc. All rights reserved.
Effects of Replication and Transcription on DNA Structure-Related Genetic Instability.

PubMed

Wang, Guliang; Vasquez, Karen M

2017-01-05

Many repetitive sequences in the human genome can adopt conformations that differ from the canonical B-DNA double helix (i.e., non-B DNA), and can impact important biological processes such as DNA replication, transcription, recombination, telomere maintenance, viral integration, transposome activation, DNA damage and repair. Thus, non-B DNA-forming sequences have been implicated in genetic instability and disease development. In this article, we discuss the interactions of non-B DNA with the replication and/or transcription machinery, particularly in disease states (e.g., tumors) that can lead to an abnormal cellular environment, and how such interactions may alter DNA replication and transcription, leading to potential conflicts at non-B DNA regions, and eventually result in genetic stability and human disease.
Effects of Replication and Transcription on DNA Structure-Related Genetic Instability

PubMed Central

Wang, Guliang; Vasquez, Karen M.

2017-01-01

Many repetitive sequences in the human genome can adopt conformations that differ from the canonical B-DNA double helix (i.e., non-B DNA), and can impact important biological processes such as DNA replication, transcription, recombination, telomere maintenance, viral integration, transposome activation, DNA damage and repair. Thus, non-B DNA-forming sequences have been implicated in genetic instability and disease development. In this article, we discuss the interactions of non-B DNA with the replication and/or transcription machinery, particularly in disease states (e.g., tumors) that can lead to an abnormal cellular environment, and how such interactions may alter DNA replication and transcription, leading to potential conflicts at non-B DNA regions, and eventually result in genetic stability and human disease. PMID:28067787
Identification of a Novel Rhabdovirus in Spodoptera frugiperda Cell Lines

PubMed Central

Ma, Hailun; Galvin, Teresa A.; Glasner, Dustin R.; Shaheduzzaman, Syed

2014-01-01

ABSTRACT The Sf9 cell line, derived from Spodoptera frugiperda, is used as a cell substrate for biological products, and no viruses have been reported in this cell line after extensive testing. We used degenerate PCR assays and massively parallel sequencing (MPS) to identify a novel RNA virus belonging to the order Mononegavirales in Sf9 cells. Sequence analysis of the assembled virus genome showed the presence of five open reading frames (ORFs) corresponding to the genes for the N, P, M, G, and L proteins in other rhabdoviruses and an unknown ORF of 111 amino acids located between the G- and L-protein genes. BLAST searches indicated that the S. frugiperda rhabdovirus (Sf-rhabdovirus) was related in a limited region of the L-protein gene to Taastrup virus, a newly discovered member of the Mononegavirales from a leafhopper (Hemiptera), and also to plant rhabdoviruses, particularly in the genus Cytorhabdovirus. Phylogenetic analysis of sequences in the L-protein gene indicated that Sf-rhabdovirus is a novel virus that branched with Taastrup virus. Rhabdovirus morphology was confirmed by transmission electron microscopy of filtered supernatant samples from Sf9 cells. Infectivity studies indicated potential transient infection by Sf-rhabdovirus in other insect cell lines, but there was no evidence of entry or virus replication in human cell lines. Sf-rhabdovirus sequences were also found in the Sf21 parental cell line of Sf9 cells but not in other insect cell lines, such as BT1-TN-5B1-4 (Tn5; High Five) cells and Schneider's Drosophila line 2 [D.Mel.(2); SL2] cells, indicating a species-specific infection. The results indicate that conventional methods may be complemented by state-of-the-art technologies with extensive bioinformatics analysis for identification of novel viruses. IMPORTANCE The Spodoptera frugiperda Sf9 cell line is used as a cell substrate for the development and manufacture of biological products. Extensive testing has not previously identified any viruses in this cell line. This paper reports on the identification and characterization of a novel rhabdovirus in Sf9 cells. This was accomplished through the use of next-generation sequencing platforms, de novo assembly tools, and extensive bioinformatics analysis. Rhabdovirus identification was further confirmed by transmission electron microscopy. Infectivity studies showed the lack of replication of Sf-rhabdovirus in human cell lines. The overall study highlights the use of a combinatorial testing approach including conventional methods and new technologies for evaluation of cell lines for unexpected viruses and use of comprehensive bioinformatics strategies for obtaining confident next-generation sequencing results. PMID:24672045
Fidelity of DNA Replication in Normal and Malignant Human Brest Cells.

DTIC Science & Technology

1995-08-31

cellular DNA replication machinery, we have initiated experiments that utilize a multiprotein DNA replication complex (MRC) isolated from breast cancer...gene in an in vitro DNA replication assay. By utilizing the target gene in a bacterial mutant selection assay we have begun to determine the...frequency with which mutational sequence errors occur as a result of the in vitro DNA replication mediated by the breast cancer cell MRC and the normal breast
Accelerated Self-Replication under Non-Equilibrium, Periodic Energy Delivery

NASA Astrophysics Data System (ADS)

Zhang, Rui; Olvera de La Cruz, Monica

2014-03-01

Self-replication is a remarkable phenomenon in nature that has fascinated scientists for decades. In a self-replicating system, the original units are attracted to a template, which induce their binding. In equilibrium, the energy required to disassemble the newly assembled copy from the mother template is supplied by thermal energy. The possibility of optimizing self-replication is explored by controlling the frequency at which energy is supplied to the system. A model system inspired by a class of light switchable colloids is considered where light is used to control the interactions. Conditions under which self-replication can be significantly more effective under non-equilibrium, cyclic energy delivery than under equilibrium constant energy conditions are identified. Optimal self-replication does not require constant energy expenditure. Instead, the proper timing at which energy is delivered to the system is an essential controllable parameter to induce high replication rates. This work was supported by the Non-Equilibrium Energy Research Center (NERC), which is an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0000989.
Novel full-length major histocompatibility complex class I allele discovery and haplotype definition in pig-tailed macaques.

PubMed

Semler, Matthew R; Wiseman, Roger W; Karl, Julie A; Graham, Michael E; Gieger, Samantha M; O'Connor, David H

2018-06-01

Pig-tailed macaques (Macaca nemestrina, Mane) are important models for human immunodeficiency virus (HIV) studies. Their infectability with minimally modified HIV makes them a uniquely valuable animal model to mimic human infection with HIV and progression to acquired immunodeficiency syndrome (AIDS). However, variation in the pig-tailed macaque major histocompatibility complex (MHC) and the impact of individual transcripts on the pathogenesis of HIV and other infectious diseases is understudied compared to that of rhesus and cynomolgus macaques. In this study, we used Pacific Biosciences single-molecule real-time circular consensus sequencing to describe full-length MHC class I (MHC-I) transcripts for 194 pig-tailed macaques from three breeding centers. We then used the full-length sequences to infer Mane-A and Mane-B haplotypes containing groups of MHC-I transcripts that co-segregate due to physical linkage. In total, we characterized full-length open reading frames (ORFs) for 313 Mane-A, Mane-B, and Mane-I sequences that defined 86 Mane-A and 106 Mane-B MHC-I haplotypes. Pacific Biosciences technology allows us to resolve these Mane-A and Mane-B haplotypes to the level of synonymous allelic variants. The newly defined haplotypes and transcript sequences containing full-length ORFs provide an important resource for infectious disease researchers as certain MHC haplotypes have been shown to provide exceptional control of simian immunodeficiency virus (SIV) replication and prevention of AIDS-like disease in nonhuman primates. The increased allelic resolution provided by Pacific Biosciences sequencing also benefits transplant research by allowing researchers to more specifically match haplotypes between donors and recipients to the level of nonsynonymous allelic variation, thus reducing the risk of graft-versus-host disease.
Open chromatin encoded in DNA sequence is the signature of ‘master’ replication origins in human cells

PubMed Central

Audit, Benjamin; Zaghloul, Lamia; Vaillant, Cédric; Chevereau, Guillaume; d'Aubenton-Carafa, Yves; Thermes, Claude; Arneodo, Alain

2009-01-01

For years, progress in elucidating the mechanisms underlying replication initiation and its coupling to transcriptional activities and to local chromatin structure has been hampered by the small number (approximately 30) of well-established origins in the human genome and more generally in mammalian genomes. Recent in silico studies of compositional strand asymmetries revealed a high level of organization of human genes around 1000 putative replication origins. Here, by comparing with recently experimentally identified replication origins, we provide further support that these putative origins are active in vivo. We show that regions ∼300-kb wide surrounding most of these putative replication origins that replicate early in the S phase are hypersensitive to DNase I cleavage, hypomethylated and present a significant enrichment in genomic energy barriers that impair nucleosome formation (nucleosome-free regions). This suggests that these putative replication origins are specified by an open chromatin structure favored by the DNA sequence. We discuss how this distinctive attribute makes these origins, further qualified as ‘master’ replication origins, priviledged loci for future research to decipher the human spatio-temporal replication program. Finally, we argue that these ‘master’ origins are likely to play a key role in genome dynamics during evolution and in pathological situations. PMID:19671527
Isolation of a Novel Insect-Specific Flavivirus from Culiseta melanura in the Northeastern United States

PubMed Central

Misencik, Michael J.; Grubaugh, Nathan D.; Andreadis, Theodore G.; Ebel, Gregory D.

2016-01-01

Abstract The genus Flavivirus includes a number of newly recognized viruses that infect and replicate only within mosquitoes. To determine whether insect-specific flaviviruses (ISFs) may infect Culiseta (Cs.) melanura mosquitoes, we screened pools of field-collected mosquitoes for virus infection by RT-PCR targeting conserved regions of the NS5 gene. NS5 nucleotide sequences amplified from Cs. melanura pools were genetically similar to other ISFs and most closely matched Calbertado virus from Culex tarsalis, sharing 68.7% nucleotide and 76.1% amino acid sequence identity. The complete genome of one virus isolate was sequenced to reveal a primary open reading frame (ORF) encoding a viral polyprotein characteristic of the genus Flavivirus. Phylogenetic analysis showed that this virus represents a distinct evolutionary lineage that belongs to the classical ISF group. The virus was detected solely in Cs. melanura pools, occurred in sampled populations from Connecticut, New York, New Hampshire, and Maine, and infected both adult and larval stages of the mosquito. Maximum likelihood estimate infection rates (MLE-IR) were relatively stable in overwintering Cs. melanura larvae collected monthly from November of 2012 through May of 2013 (MLE-IR = 0.7–2.1/100 mosquitoes) and in host-seeking females collected weekly from June through October of 2013 (MLE-IR = 3.8–11.5/100 mosquitoes). Phylogenetic analysis of viral sequences revealed limited genetic variation that lacked obvious geographic structure among strains in the northeastern United States. This new virus is provisionally named Culiseta flavivirus on the basis of its host association with Cs. melanura. PMID:26807512
Arrays of probes for positional sequencing by hybridization

DOEpatents

Cantor, Charles R [Boston, MA; Prezetakiewiczr, Marek [East Boston, MA; Smith, Cassandra L [Boston, MA; Sano, Takeshi [Waltham, MA

2008-01-15

This invention is directed to methods and reagents useful for sequencing nucleic acid targets utilizing sequencing by hybridization technology comprising probes, arrays of probes and methods whereby sequence information is obtained rapidly and efficiently in discrete packages. That information can be used for the detection, identification, purification and complete or partial sequencing of a particular target nucleic acid. When coupled with a ligation step, these methods can be performed under a single set of hybridization conditions. The invention also relates to the replication of probe arrays and methods for making and replicating arrays of probes which are useful for the large scale manufacture of diagnostic aids used to screen biological samples for specific target sequences. Arrays created using PCR technology may comprise probes with 5'- and/or 3'-overhangs.
A Bayesian hierarchical model to detect differentially methylated loci from single nucleotide resolution sequencing data

PubMed Central

Feng, Hao; Conneely, Karen N.; Wu, Hao

2014-01-01

DNA methylation is an important epigenetic modification that has essential roles in cellular processes including gene regulation, development and disease and is widely dysregulated in most types of cancer. Recent advances in sequencing technology have enabled the measurement of DNA methylation at single nucleotide resolution through methods such as whole-genome bisulfite sequencing and reduced representation bisulfite sequencing. In DNA methylation studies, a key task is to identify differences under distinct biological contexts, for example, between tumor and normal tissue. A challenge in sequencing studies is that the number of biological replicates is often limited by the costs of sequencing. The small number of replicates leads to unstable variance estimation, which can reduce accuracy to detect differentially methylated loci (DML). Here we propose a novel statistical method to detect DML when comparing two treatment groups. The sequencing counts are described by a lognormal-beta-binomial hierarchical model, which provides a basis for information sharing across different CpG sites. A Wald test is developed for hypothesis testing at each CpG site. Simulation results show that the proposed method yields improved DML detection compared to existing methods, particularly when the number of replicates is low. The proposed method is implemented in the Bioconductor package DSS. PMID:24561809

Sterol Binding by the Tombusviral Replication Proteins Is Essential for Replication in Yeast and Plants.

PubMed

Xu, Kai; Nagy, Peter D

2017-04-01

Membranous structures derived from various organelles are important for replication of plus-stranded RNA viruses. Although the important roles of co-opted host proteins in RNA virus replication have been appreciated for a decade, the equally important functions of cellular lipids in virus replication have been gaining full attention only recently. Previous work with Tomato bushy stunt tombusvirus (TBSV) in model host yeast has revealed essential roles for phosphatidylethanolamine and sterols in viral replication. To further our understanding of the role of sterols in tombusvirus replication, in this work we showed that the TBSV p33 and p92 replication proteins could bind to sterols in vitro The sterol binding by p33 is supported by cholesterol recognition/interaction amino acid consensus (CRAC) and CARC-like sequences within the two transmembrane domains of p33. Mutagenesis of the critical Y amino acids within the CRAC and CARC sequences blocked TBSV replication in yeast and plant cells. We also showed the enrichment of sterols in the detergent-resistant membrane (DRM) fractions obtained from yeast and plant cells replicating TBSV. The DRMs could support viral RNA synthesis on both the endogenous and exogenous templates. A lipidomic approach showed the lack of enhancement of sterol levels in yeast and plant cells replicating TBSV. The data support the notion that the TBSV replication proteins are associated with sterol-rich detergent-resistant membranes in yeast and plant cells. Together, the results obtained in this study and the previously published results support the local enrichment of sterols around the viral replication proteins that is critical for TBSV replication. IMPORTANCE One intriguing aspect of viral infections is their dependence on efficient subcellular assembly platforms serving replication, virion assembly, or virus egress via budding out of infected cells. These assembly platforms might involve sterol-rich membrane microdomains, which are heterogeneous and highly dynamic nanoscale structures usurped by various viruses. Here, we demonstrate that TBSV p33 and p92 replication proteins can bind to sterol in vitro Mutagenesis analysis of p33 within the CRAC and CARC sequences involved in sterol binding shows the important connection between the abilities of p33 to bind to sterol and to support TBSV replication in yeast and plant cells. Together, the results further strengthen the model that cellular sterols are essential as proviral lipids during viral replication. Copyright © 2017 American Society for Microbiology.
Method for replicating an array of nucleic acid probes

DOEpatents

Cantor, Charles R.; Przetakiewicz, Marek; Smith, Cassandra L.; Sano, Takeshi

1998-01-01

The invention relates to the replication of probe arrays and methods for replicating arrays of probes which are useful for the large scale manufacture of diagnostic aids used to screen biological samples for specific target sequences. Arrays created using PCR technology may comprise probes with 5'- and/or 3'-overhangs.
Megabase replication domains along the human genome: relation to chromatin structure and genome organisation.

PubMed

Audit, Benjamin; Zaghloul, Lamia; Baker, Antoine; Arneodo, Alain; Chen, Chun-Long; d'Aubenton-Carafa, Yves; Thermes, Claude

2013-01-01

In higher eukaryotes, the absence of specific sequence motifs, marking the origins of replication has been a serious hindrance to the understanding of (i) the mechanisms that regulate the spatio-temporal replication program, and (ii) the links between origins activation, chromatin structure and transcription. In this chapter, we review the partitioning of the human genome into megabased-size replication domains delineated as N-shaped motifs in the strand compositional asymmetry profiles. They collectively span 28.3% of the genome and are bordered by more than 1,000 putative replication origins. We recapitulate the comparison of this partition of the human genome with high-resolution experimental data that confirms that replication domain borders are likely to be preferential replication initiation zones in the germline. In addition, we highlight the specific distribution of experimental and numerical chromatin marks along replication domains. Domain borders correspond to particular open chromatin regions, possibly encoded in the DNA sequence, and around which replication and transcription are highly coordinated. These regions also present a high evolutionary breakpoint density, suggesting that susceptibility to breakage might be linked to local open chromatin fiber state. Altogether, this chapter presents a compartmentalization of the human genome into replication domains that are landmarks of the human genome organization and are likely to play a key role in genome dynamics during evolution and in pathological situations.
A conserved mechanism for replication origin recognition and binding in archaea.

PubMed

Majerník, Alan I; Chong, James P J

2008-01-15

To date, methanogens are the only group within the archaea where firing DNA replication origins have not been demonstrated in vivo. In the present study we show that a previously identified cluster of ORB (origin recognition box) sequences do indeed function as an origin of replication in vivo in the archaeon Methanothermobacter thermautotrophicus. Although the consensus sequence of ORBs in M. thermautotrophicus is somewhat conserved when compared with ORB sequences in other archaea, the Cdc6-1 protein from M. thermautotrophicus (termed MthCdc6-1) displays sequence-specific binding that is selective for the MthORB sequence and does not recognize ORBs from other archaeal species. Stabilization of in vitro MthORB DNA binding by MthCdc6-1 requires additional conserved sequences 3' to those originally described for M. thermautotrophicus. By testing synthetic sequences bearing mutations in the MthORB consensus sequence, we show that Cdc6/ORB binding is critically dependent on the presence of an invariant guanine found in all archaeal ORB sequences. Mutation of a universally conserved arginine residue in the recognition helix of the winged helix domain of archaeal Cdc6-1 shows that specific origin sequence recognition is dependent on the interaction of this arginine residue with the invariant guanine. Recognition of a mutated origin sequence can be achieved by mutation of the conserved arginine residue to a lysine or glutamine residue. Thus despite a number of differences in protein and DNA sequences between species, the mechanism of origin recognition and binding appears to be conserved throughout the archaea.
Ultra-low background DNA cloning system.

PubMed

Goto, Kenta; Nagano, Yukio

2013-01-01

Yeast-based in vivo cloning is useful for cloning DNA fragments into plasmid vectors and is based on the ability of yeast to recombine the DNA fragments by homologous recombination. Although this method is efficient, it produces some by-products. We have developed an "ultra-low background DNA cloning system" on the basis of yeast-based in vivo cloning, by almost completely eliminating the generation of by-products and applying the method to commonly used Escherichia coli vectors, particularly those lacking yeast replication origins and carrying an ampicillin resistance gene (Amp(r)). First, we constructed a conversion cassette containing the DNA sequences in the following order: an Amp(r) 5' UTR (untranslated region) and coding region, an autonomous replication sequence and a centromere sequence from yeast, a TRP1 yeast selectable marker, and an Amp(r) 3' UTR. This cassette allowed conversion of the Amp(r)-containing vector into the yeast/E. coli shuttle vector through use of the Amp(r) sequence by homologous recombination. Furthermore, simultaneous transformation of the desired DNA fragment into yeast allowed cloning of this DNA fragment into the same vector. We rescued the plasmid vectors from all yeast transformants, and by-products containing the E. coli replication origin disappeared. Next, the rescued vectors were transformed into E. coli and the by-products containing the yeast replication origin disappeared. Thus, our method used yeast- and E. coli-specific "origins of replication" to eliminate the generation of by-products. Finally, we successfully cloned the DNA fragment into the vector with almost 100% efficiency.
Detection of hepatitis C virus sequences in brain tissue obtained in recurrent hepatitis C after liver transplantation.

PubMed

Vargas, Hugo E; Laskus, Tomasz; Radkowski, Marek; Wilkinson, Jeff; Balan, Vijay; Douglas, David D; Harrison, M Edwyn; Mulligan, David C; Olden, Kevin; Adair, Debra; Rakela, Jorge

2002-11-01

Patients with chronic hepatitis C frequently report tiredness, easy fatigability, and depression. The aim of this study is to determine whether hepatitis C virus (HCV) replication could be found in brain tissue in patients with hepatitis C and depression. We report two patients with recurrent hepatitis C after liver transplantation who also developed severe depression. One patient died of multiorgan failure and the other, septicemia caused by Staphylococcus aureussis. Both patients had evidence of severe hepatitis C recurrence with features of cholestatic fibrosing hepatitis. We were able to study samples of their central nervous system obtained at autopsy for evidence of HCV replication. The presence of HCV RNA-negative strand, which is the viral replicative form, was determined by strand-specific Tth-based reverse-transcriptase polymerase chain reaction. Viral sequences were compared by means of single-strand conformation polymorphism and direct sequencing. HCV RNA-negative strands were found in subcortical white matter from one patient and cerebral cortex from the other patient. HCV RNA-negative strands amplified from brain tissue differed by several nucleotide substitutions from serum consensus sequences in the 5' untranslated region. These findings support the concept of HCV neuroinvasion, and we speculate that it may provide a biological substrate to neuropsychiatric disorders observed in patients with chronic hepatitis C. The exact lineage of cells permissive for HCV replication and the possible interaction between viral replication and cerebral function that may lead to depression remain to be elucidated.
Cloning and characterization of an autonomous replication sequence from Coxiella burnetii.

PubMed Central

Suhan, M; Chen, S Y; Thompson, H A; Hoover, T A; Hill, A; Williams, J C

1994-01-01

A Coxiella burnetii chromosomal fragment capable of functioning as an origin for the replication of a kanamycin resistance (Kanr) plasmid was isolated by use of origin search methods utilizing an Escherichia coli host. The 5.8-kb fragment was subcloned into phagemid vectors and was deleted progressively by an exonuclease III-S1 technique. Plasmids containing progressively shorter DNA fragments were then tested for their capability to support replication by transformation of an E. coli polA strain. A minimal autonomous replication sequence (ARS) was delimited to 403 bp. Sequencing of the entire 5.8-kb region revealed that the minimal ARS contained two consensus DnaA boxes, three A + T-rich 21-mers, a transcriptional promoter leading rightwards, and potential integration host factor and factor of inversion stimulation binding sites. Database comparisons of deduced amino acid sequences revealed that open reading frames located around the ARS were homologous to genes often, but not always, found near bacterial chromosomal origins; these included identities with rpmH and rnpA in E. coli and identities with the 9K protein and 60K membrane protein in E. coli and Pseudomonas species. These and direct hybridization data suggested that the ARS was chromosomal and not associated with the resident plasmid QpH1. Two-dimensional agarose gel electrophoresis did not reveal the presence of initiating intermediates, indicating that the ARS did not initiate chromosome replication during laboratory growth of C. burnetii. Images PMID:8071197
High-efficiency transformation of Pichia stipitis based on its URA3 gene and a homologous autonomous replication sequence, ARS2.

PubMed Central

Yang, V W; Marks, J A; Davis, B P; Jeffries, T W

1994-01-01

This paper describes the first high-efficiency transformation system for the xylose-fermenting yeast Pichia stipitis. The system includes integrating and autonomously replicating plasmids based on the gene for orotidine-5'-phosphate decarboxylase (URA3) and an autonomous replicating sequence (ARS) element (ARS2) isolated from P. stipitis CBS 6054. Ura- auxotrophs were obtained by selecting for resistance to 5-fluoroorotic acid and were identified as ura3 mutants by transformation with P. stipitis URA3. P. stipitis URA3 was cloned by its homology to Saccharomyces cerevisiae URA3, with which it is 69% identical in the coding region. P. stipitis ARS elements were cloned functionally through plasmid rescue. These sequences confer autonomous replication when cloned into vectors bearing the P. stipitis URA3 gene. P. stipitis ARS2 has features similar to those of the consensus ARS of S. cerevisiae and other ARS elements. Circular plasmids bearing the P. stipitis URA3 gene with various amounts of flanking sequences produced 600 to 8,600 Ura+ transformants per micrograms of DNA by electroporation. Most transformants obtained with circular vectors arose without integration of vector sequences. One vector yielded 5,200 to 12,500 Ura+ transformants per micrograms of DNA after it was linearized at various restriction enzyme sites within the P. stipitis URA3 insert. Transformants arising from linearized vectors produced stable integrants, and integration events were site specific for the genomic ura3 in 20% of the transformants examined. Plasmids bearing the P. stipitis URA3 gene and ARS2 element produced more than 30,000 transformants per micrograms of plasmid DNA. Autonomously replicating plasmids were stable for at least 50 generations in selection medium and were present at an average of 10 copies per nucleus. Images PMID:7811063
Regulation of Replication Fork Advance and Stability by Nucleosome Assembly

PubMed Central

Prado, Felix; Maya, Douglas

2017-01-01

The advance of replication forks to duplicate chromosomes in dividing cells requires the disassembly of nucleosomes ahead of the fork and the rapid assembly of parental and de novo histones at the newly synthesized strands behind the fork. Replication-coupled chromatin assembly provides a unique opportunity to regulate fork advance and stability. Through post-translational histone modifications and tightly regulated physical and genetic interactions between chromatin assembly factors and replisome components, chromatin assembly: (1) controls the rate of DNA synthesis and adjusts it to histone availability; (2) provides a mechanism to protect the integrity of the advancing fork; and (3) regulates the mechanisms of DNA damage tolerance in response to replication-blocking lesions. Uncoupling DNA synthesis from nucleosome assembly has deleterious effects on genome integrity and cell cycle progression and is linked to genetic diseases, cancer, and aging. PMID:28125036
Origin-Dependent Inverted-Repeat Amplification: Tests of a Model for Inverted DNA Amplification

PubMed Central

Brewer, Bonita J.; Payen, Celia; Di Rienzi, Sara C.; Higgins, Megan M.; Ong, Giang; Dunham, Maitreya J.; Raghuraman, M. K.

2015-01-01

DNA replication errors are a major driver of evolution—from single nucleotide polymorphisms to large-scale copy number variations (CNVs). Here we test a specific replication-based model to explain the generation of interstitial, inverted triplications. While no genetic information is lost, the novel inversion junctions and increased copy number of the included sequences create the potential for adaptive phenotypes. The model—Origin-Dependent Inverted-Repeat Amplification (ODIRA)—proposes that a replication error at pre-existing short, interrupted, inverted repeats in genomic sequences generates an extrachromosomal, inverted dimeric, autonomously replicating intermediate; subsequent genomic integration of the dimer yields this class of CNV without loss of distal chromosomal sequences. We used a combination of in vitro and in vivo approaches to test the feasibility of the proposed replication error and its downstream consequences on chromosome structure in the yeast Saccharomyces cerevisiae. We show that the proposed replication error—the ligation of leading and lagging nascent strands to create “closed” forks—can occur in vitro at short, interrupted inverted repeats. The removal of molecules with two closed forks results in a hairpin-capped linear duplex that we show replicates in vivo to create an inverted, dimeric plasmid that subsequently integrates into the genome by homologous recombination, creating an inverted triplication. While other models have been proposed to explain inverted triplications and their derivatives, our model can also explain the generation of human, de novo, inverted amplicons that have a 2:1 mixture of sequences from both homologues of a single parent—a feature readily explained by a plasmid intermediate that arises from one homologue and integrates into the other homologue prior to meiosis. Our tests of key features of ODIRA lend support to this mechanism and suggest further avenues of enquiry to unravel the origins of interstitial, inverted CNVs pivotal in human health and evolution. PMID:26700858
Origin-Dependent Inverted-Repeat Amplification: Tests of a Model for Inverted DNA Amplification.

PubMed

Brewer, Bonita J; Payen, Celia; Di Rienzi, Sara C; Higgins, Megan M; Ong, Giang; Dunham, Maitreya J; Raghuraman, M K

2015-12-01

DNA replication errors are a major driver of evolution--from single nucleotide polymorphisms to large-scale copy number variations (CNVs). Here we test a specific replication-based model to explain the generation of interstitial, inverted triplications. While no genetic information is lost, the novel inversion junctions and increased copy number of the included sequences create the potential for adaptive phenotypes. The model--Origin-Dependent Inverted-Repeat Amplification (ODIRA)-proposes that a replication error at pre-existing short, interrupted, inverted repeats in genomic sequences generates an extrachromosomal, inverted dimeric, autonomously replicating intermediate; subsequent genomic integration of the dimer yields this class of CNV without loss of distal chromosomal sequences. We used a combination of in vitro and in vivo approaches to test the feasibility of the proposed replication error and its downstream consequences on chromosome structure in the yeast Saccharomyces cerevisiae. We show that the proposed replication error-the ligation of leading and lagging nascent strands to create "closed" forks-can occur in vitro at short, interrupted inverted repeats. The removal of molecules with two closed forks results in a hairpin-capped linear duplex that we show replicates in vivo to create an inverted, dimeric plasmid that subsequently integrates into the genome by homologous recombination, creating an inverted triplication. While other models have been proposed to explain inverted triplications and their derivatives, our model can also explain the generation of human, de novo, inverted amplicons that have a 2:1 mixture of sequences from both homologues of a single parent--a feature readily explained by a plasmid intermediate that arises from one homologue and integrates into the other homologue prior to meiosis. Our tests of key features of ODIRA lend support to this mechanism and suggest further avenues of enquiry to unravel the origins of interstitial, inverted CNVs pivotal in human health and evolution.
Replicase activity of purified recombinant protein P2 of double-stranded RNA bacteriophage phi6.

PubMed

Makeyev, E V; Bamford, D H

2000-01-04

In nature, synthesis of both minus- and plus-sense RNA strands of all the known double-stranded RNA viruses occurs in the interior of a large protein assembly referred to as the polymerase complex. In addition to other proteins, the complex contains a putative polymerase possessing characteristic sequence motifs. However, none of the previous studies has shown template-dependent RNA synthesis directly with an isolated putative polymerase protein. In this report, recombinant protein P2 of double-stranded RNA bacteriophage phi6 was purified and demonstrated in an in vitro enzymatic assay to act as the replicase. The enzyme efficiently utilizes phage-specific, positive-sense RNA substrates to produce double-stranded RNA molecules, which are formed by newly synthesized, full-length minus-strands base paired with the plus-strand templates. P2-catalyzed replication is also shown to be very effective with a broad range of heterologous single-stranded RNA templates. The importance and implications of these results are discussed.
Characterization of replication and conjugation of plasmid pWTY27 from a widely distributed Streptomyces species

PubMed Central

2012-01-01

Background Streptomyces species are widely distributed in natural habitats, such as soils, lakes, plants and some extreme environments. Replication loci of several Streptomyces theta-type plasmids have been reported, but are not characterized in details. Conjugation loci of some Streptomyces rolling-circle-type plasmids are identified and mechanism of conjugal transferring are described. Results We report the detection of a widely distributed Streptomyces strain Y27 and its indigenous plasmid pWTY27 from fourteen plants and four soil samples cross China by both culturing and nonculturing methods. The complete nucleotide sequence of pWTY27 consisted of 14,288 bp. A basic locus for plasmid replication comprised repAB genes and an adjacent iteron sequence, to a long inverted-repeat (ca. 105 bp) of which the RepA protein bound specifically in vitro, suggesting that RepA may recognize a second structure (e.g. a long stem-loop) of the iteron DNA. A plasmid containing the locus propagated in linear mode when the telomeres of a linear plasmid were attached, indicating a bi-directional replication mode for pWTY27. As for rolling-circle plasmids, a single traA gene and a clt sequence (covering 16 bp within traA and its adjacent 159 bp) on pWTY27 were required for plasmid transfer. TraA recognized and bound specifically to the two regions of the clt sequence, one containing all the four DC1 of 7 bp (TGACACC) and one DC2 (CCCGCCC) and most of IC1, and another covering two DC2 and part of IC1, suggesting formation of a high-ordered DNA-protein complex. Conclusions This work (i) isolates a widespread Streptomyces strain Y27 and sequences its indigenous theta-type plasmid pWTY27; (ii) identifies the replication and conjugation loci of pWTY27 and; (iii) characterizes the binding sequences of the RepA and TraA proteins. PMID:23134842
Recombination in Enteroviruses Is a Biphasic Replicative Process Involving the Generation of Greater-than Genome Length ‘Imprecise’ Intermediates

PubMed Central

Lowry, Kym; Woodman, Andrew; Cook, Jonathan; Evans, David J.

2014-01-01

Recombination in enteroviruses provides an evolutionary mechanism for acquiring extensive regions of novel sequence, is suggested to have a role in genotype diversity and is known to have been key to the emergence of novel neuropathogenic variants of poliovirus. Despite the importance of this evolutionary mechanism, the recombination process remains relatively poorly understood. We investigated heterologous recombination using a novel reverse genetic approach that resulted in the isolation of intermediate chimeric intertypic polioviruses bearing genomes with extensive duplicated sequences at the recombination junction. Serial passage of viruses exhibiting such imprecise junctions yielded progeny with increased fitness which had lost the duplicated sequences. Mutations or inhibitors that changed polymerase fidelity or the coalescence of replication complexes markedly altered the yield of recombinants (but did not influence non-replicative recombination) indicating both that the process is replicative and that it may be possible to enhance or reduce recombination-mediated viral evolution if required. We propose that extant recombinants result from a biphasic process in which an initial recombination event is followed by a process of resolution, deleting extraneous sequences and optimizing viral fitness. This process has implications for our wider understanding of ‘evolution by duplication’ in the positive-strand RNA viruses. PMID:24945141
A new series of yeast shuttle vectors for the recovery and identification of multiple plasmids from Saccharomyces cerevisiae.

PubMed

Frazer, LilyAnn Novak; O'Keefe, Raymond T

2007-09-01

The availability of Saccharomyces cerevisiae yeast strains with multiple auxotrophic markers allows the stable introduction and selection of more than one yeast shuttle vector containing marker genes that complement the auxotrophic markers. In certain experimental situations there is a need to recover more than one shuttle vector from yeast. To facilitate the recovery and identification of multiple plasmids from S. cerevisiae, we have constructed a series of plasmids based on the pRS series of yeast shuttle vectors. Bacterial antibiotic resistance genes to chloramphenicol, kanamycin and zeocin have been combined with the yeast centromere sequence (CEN6), the autonomously replicating sequence (ARSH4) and one of the four yeast selectable marker genes (HIS3, TRP1, LEU2 or URA3) from the pRS series of vectors. The 12 plasmids produced differ in antibiotic resistance and yeast marker gene within the backbone of the multipurpose plasmid pBluescript II. The newly constructed vectors show similar mitotic stability to the original pRS vectors. In combination with the ampicillin-resistant pRS series of yeast shuttle vectors, these plasmids now allow the recovery and identification in bacteria of up to four different vectors from S. cerevisiae. Copyright (c) 2007 John Wiley & Sons, Ltd.
Emergence of a replicating species from an in vitro RNA evolution reaction

NASA Technical Reports Server (NTRS)

Breaker, R. R.; Joyce, G. F.

1994-01-01

The technique of self-sustained sequence replication allows isothermal amplification of DNA and RNA molecules in vitro. This method relies on the activities of a reverse transcriptase and a DNA-dependent RNA polymerase to amplify specific nucleic acid sequences. We have modified this protocol to allow selective amplification of RNAs that catalyze a particular chemical reaction. During an in vitro RNA evolution experiment employing this modified system, a unique class of "selfish" RNAs emerged and replicated to the exclusion of the intended RNAs. Members of this class of selfish molecules, termed RNA Z, amplify efficiently despite their inability to catalyze the target chemical reaction. Their amplification requires the action of both reverse transcriptase and RNA polymerase and involves the synthesis of both DNA and RNA replication intermediates. The proposed amplification mechanism for RNA Z involves the formation of a DNA hairpin that functions as a template for transcription by RNA polymerase. This arrangement links the two strands of the DNA, resulting in the production of RNA transcripts that contain an embedded RNA polymerase promoter sequence.
Prolactin Regulatory Element Binding Protein Is Involved in Hepatitis C Virus Replication by Interaction with NS4B

PubMed Central

Kong, Lingbao; Fujimoto, Akira; Nakamura, Mariko; Aoyagi, Haruyo; Matsuda, Mami; Watashi, Koichi; Suzuki, Ryosuke; Arita, Minetaro; Yamagoe, Satoshi; Dohmae, Naoshi; Suzuki, Takehiro; Sakamaki, Yuriko; Ichinose, Shizuko; Suzuki, Tetsuro; Wakita, Takaji

2016-01-01

ABSTRACT It has been proposed that the hepatitis C virus (HCV) NS4B protein triggers the membranous HCV replication compartment, but the underlying molecular mechanism is not fully understood. Here, we screened for NS4B-associated membrane proteins by tandem affinity purification and proteome analysis and identified 202 host proteins. Subsequent screening of replicon cells with small interfering RNA identified prolactin regulatory element binding (PREB) to be a novel HCV host cofactor. The interaction between PREB and NS4B was confirmed by immunoprecipitation, immunofluorescence, and proximity ligation assays. PREB colocalized with double-stranded RNA and the newly synthesized HCV RNA labeled with bromouridine triphosphate in HCV replicon cells. Furthermore, PREB shifted to detergent-resistant membranes (DRMs), where HCV replication complexes reside, in the presence of NS4B expression in Huh7 cells. However, a PREB mutant lacking the NS4B-binding region (PREBd3) could not colocalize with double-stranded RNA and did not shift to the DRM in the presence of NS4B. These results indicate that PREB locates at the HCV replication complex by interacting with NS4B. PREB silencing inhibited the formation of the membranous HCV replication compartment and increased the protease and nuclease sensitivity of HCV replicase proteins and RNA in DRMs, respectively. Collectively, these data indicate that PREB promotes HCV RNA replication by participating in the formation of the membranous replication compartment and by maintaining its proper structure by interacting with NS4B. Furthermore, PREB was induced by HCV infection in vitro and in vivo. Our findings provide new insights into HCV host cofactors. IMPORTANCE The hepatitis C virus (HCV) protein NS4B can induce alteration of the endoplasmic reticulum and the formation of a membranous web structure, which provides a platform for the HCV replication complex. The molecular mechanism by which NS4B induces the membranous HCV replication compartment is not understood. We screened for NS4B-associated membrane proteins by tandem affinity purification and proteome analysis, followed by screening with small interfering RNA. We identified prolactin regulatory element binding (PREB) to be a novel HCV host cofactor. PREB is induced by HCV infection and recruited into the replication complex by interaction with NS4B. Recruited PREB promotes HCV RNA replication by participating in the formation of the membranous HCV replication compartment. To our knowledge, the effect of NS4B-binding protein on the formation of the membranous HCV replication compartment is newly described in this report. Our findings are expected to provide new insights into HCV host cofactors. PMID:26739056
Replication Protein A-1 Has a Preference for the Telomeric G-rich Sequence in Trypanosoma cruzi.

PubMed

Pavani, Raphael Souza; Vitarelli, Marcela O; Fernandes, Carlos A H; Mattioli, Fabio F; Morone, Mariana; Menezes, Milene C; Fontes, Marcos R M; Cano, Maria Isabel N; Elias, Maria Carolina

2018-05-01

Replication protein A (RPA), the major eukaryotic single-stranded binding protein, is a heterotrimeric complex formed by RPA-1, RPA-2, and RPA-3. RPA is a fundamental player in replication, repair, recombination, and checkpoint signaling. In addition, increasing evidences have been adding functions to RPA in telomere maintenance, such as interaction with telomerase to facilitate its activity and also involvement in telomere capping in some conditions. Trypanosoma cruzi, the etiological agent of Chagas disease is a protozoa parasite that appears early in the evolution of eukaryotes. Recently, we have showed that T. cruziRPA presents canonical functions being involved with DNA replication and DNA damage response. Here, we found by FISH/IF assays that T. cruziRPA localizes at telomeres even outside replication (S) phase. In vitro analysis showed that one telomeric repeat is sufficient to bind RPA-1. Telomeric DNA induces different secondary structural modifications on RPA-1 in comparison with other types of DNA. In addition, RPA-1 presents a higher affinity for telomeric sequence compared to randomic sequence, suggesting that RPA may play specific roles in T. cruzi telomeric region. © 2017 The Author(s) Journal of Eukaryotic Microbiology © 2017 International Society of Protistologists.
G-quadruplex-interacting compounds alter latent DNA replication and episomal persistence of KSHV

PubMed Central

Madireddy, Advaitha; Purushothaman, Pravinkumar; Loosbroock, Christopher P.; Robertson, Erle S.; Schildkraut, Carl L.; Verma, Subhash C.

2016-01-01

Kaposi's sarcoma associated herpesvirus (KSHV) establishes life-long latent infection by persisting as an extra-chromosomal episome in the infected cells and by maintaining its genome in dividing cells. KSHV achieves this by tethering its epigenome to the host chromosome by latency associated nuclear antigen (LANA), which binds in the terminal repeat (TR) region of the viral genome. Sequence analysis of the TR, a GC-rich DNA element, identified several potential Quadruplex G-Rich Sequences (QGRS). Since quadruplexes have the tendency to obstruct DNA replication, we used G-quadruplex stabilizing compounds to examine their effect on latent DNA replication and the persistence of viral episomes. Our results showed that these G-quadruplex stabilizing compounds led to the activation of dormant origins of DNA replication, with preferential bi-directional pausing of replications forks moving out of the TR region, implicating the role of the G-rich TR in the perturbation of episomal DNA replication. Over time, treatment with PhenDC3 showed a loss of viral episomes in the infected cells. Overall, these data show that G-quadruplex stabilizing compounds retard the progression of replication forks leading to a reduction in DNA replication and episomal maintenance. These results suggest a potential role for G-quadruplex stabilizers in the treatment of KSHV-associated diseases. PMID:26837574
Method for replicating an array of nucleic acid probes

DOEpatents

Cantor, C.R.; Przetakiewicz, M.; Smith, C.L.; Sano, T.

1998-08-18

The invention relates to the replication of probe arrays and methods for replicating arrays of probes which are useful for the large scale manufacture of diagnostic aids used to screen biological samples for specific target sequences. Arrays created using PCR technology may comprise probes with 5{prime}- and/or 3{prime}-overhangs. 16 figs.

Functional Characterization of Adaptive Mutations during the West African Ebola Virus Outbreak.

PubMed

Dietzel, Erik; Schudt, Gordian; Krähling, Verena; Matrosovich, Mikhail; Becker, Stephan

2017-01-15

The Ebola virus (EBOV) outbreak in West Africa started in December 2013, claimed more than 11,000 lives, threatened to destabilize a whole region, and showed how easily health crises can turn into humanitarian disasters. EBOV genomic sequences of the West African outbreak revealed nonsynonymous mutations, which induced considerable public attention, but their role in virus spread and disease remains obscure. In this study, we investigated the functional significance of three nonsynonymous mutations that emerged early during the West African EBOV outbreak. Almost 90% of more than 1,000 EBOV genomes sequenced during the outbreak carried the signature of three mutations: a D759G substitution in the active center of the L polymerase, an A82V substitution in the receptor binding domain of surface glycoprotein GP, and an R111C substitution in the self-assembly domain of RNA-encapsidating nucleoprotein NP. Using a newly developed virus-like particle system and reverse genetics, we found that the mutations have an impact on the functions of the respective viral proteins and on the growth of recombinant EBOVs. The mutation in L increased viral transcription and replication, whereas the mutation in NP decreased viral transcription and replication. The mutation in the receptor binding domain of the glycoprotein GP improved the efficiency of GP-mediated viral entry into target cells. Recombinant EBOVs with combinations of the three mutations showed a growth advantage over the prototype isolate Makona C7 lacking the mutations. This study showed that virus variants with improved fitness emerged early during the West African EBOV outbreak. The dimension of the Ebola virus outbreak in West Africa was unprecedented. Amino acid substitutions in the viral L polymerase, surface glycoprotein GP, and nucleocapsid protein NP emerged, were fixed early in the outbreak, and were found in almost 90% of the sequences. Here we showed that these mutations affected the functional activity of viral proteins and improved viral growth in cell culture. Our results demonstrate emergence of adaptive changes in the Ebola virus genome during virus circulation in humans and prompt further studies on the potential role of these changes in virus transmissibility and pathogenicity. Copyright © 2017 American Society for Microbiology.
Molecular cloning of MSSP-2, a c-myc gene single-strand binding protein: characterization of binding specificity and DNA replication activity.

PubMed Central

Takai, T; Nishita, Y; Iguchi-Ariga, S M; Ariga, H

1994-01-01

We have previously reported the human cDNA encoding MSSP-1, a sequence-specific double- and single-stranded DNA binding protein [Negishi, Nishita, Saëgusa, Kakizaki, Galli, Kihara, Tamai, Miyajima, Iguchi-Ariga and Ariga (1994) Oncogene, 9, 1133-1143]. MSSP-1 binds to a DNA replication origin/transcriptional enhancer of the human c-myc gene and has turned out to be identical with Scr2, a human protein which complements the defect of cdc2 kinase in S.pombe [Kataoka and Nojima (1994) Nucleic Acid Res., 22, 2687-2693]. We have cloned the cDNA for MSSP-2, another member of the MSSP family of proteins. The MSSP-2 cDNA shares highly homologous sequences with MSSP-1 cDNA, except for the insertion of 48 bp coding 16 amino acids near the C-terminus. Like MSSP-1, MSSP-2 has RNP-1 consensus sequences. The results of the experiments using bacterially expressed MSSP-2, and its deletion mutants, as histidine fusion proteins suggested that the binding specificity of MSSP-2 to double- and single-stranded DNA is the same as that of MSSP-1, and that the RNP consensus sequences are required for the DNA binding of the protein. MSSP-2 stimulated the DNA replication of an SV40-derived plasmid containing the binding sequence for MSSP-1 or -2. MSSP-2 is hence suggested to play an important role in regulation of DNA replication. Images PMID:7838710
Codon usage in Chlamydia trachomatis is the result of strand-specific mutational biases and a complex pattern of selective forces

PubMed Central

Romero, Héctor; Zavala, Alejandro; Musto, Héctor

2000-01-01

The patterns of synonymous codon choices of the completely sequenced genome of the bacterium Chlamydia trachomatis were analysed. We found that the most important source of variation among the genes results from whether the sequence is located on the leading or lagging strand of replication, resulting in an over representation of G or C, respectively. This can be explained by different mutational biases associated to the different enzymes that replicate each strand. Next we found that most highly expressed sequences are located on the leading strand of replication. From this result, replicational-transcriptional selection can be invoked. Then, when the genes located on the leading strand are studied separately, the correspondence analysis detects a principal trend which discriminates between lowly and highly expressed sequences, the latter displaying a different codon usage pattern than the former, suggesting selection for translation, which is reinforced by the fact that Ks values between orthologous sequences from C.trachomatis and Chlamydia pneumoniae are much smaller in highly expressed genes. Finally, synonymous codon choices appear to be influenced by the hydropathy of each encoded protein and by the degree of amino acid conservation. Therefore, synonymous codon usage in C.trachomatis seems to be the result of a very complex balance among different factors, which rises the problem of whether the forces driving codon usage patterns among microorganisms are rather more complex than generally accepted. PMID:10773076
Codon usage in Chlamydia trachomatis is the result of strand-specific mutational biases and a complex pattern of selective forces.

PubMed

Romero, H; Zavala, A; Musto, H

2000-05-15

The patterns of synonymous codon choices of the completely sequenced genome of the bacterium Chlamydia trachomatis were analysed. We found that the most important source of variation among the genes results from whether the sequence is located on the leading or lagging strand of replication, resulting in an over representation of G or C, respectively. This can be explained by different mutational biases associated to the different enzymes that replicate each strand. Next we found that most highly expressed sequences are located on the leading strand of replication. From this result, replicational-transcriptional selection can be invoked. Then, when the genes located on the leading strand are studied separately, the correspondence analysis detects a principal trend which discriminates between lowly and highly expressed sequences, the latter displaying a different codon usage pattern than the former, suggesting selection for translation, which is reinforced by the fact that Ks values between orthologous sequences from C. trachomatis and Chlamydia pneumoniae are much smaller in highly expressed genes. Finally, synonymous codon choices appear to be influenced by the hydropathy of each encoded protein and by the degree of amino acid conservation. Therefore, synonymous codon usage in C.trachomatis seems to be the result of a very complex balance among different factors, which rises the problem of whether the forces driving codon usage patterns among microorganisms are rather more complex than generally accepted.
Cohesin Can Remain Associated with Chromosomes during DNA Replication.

PubMed

Rhodes, James D P; Haarhuis, Judith H I; Grimm, Jonathan B; Rowland, Benjamin D; Lavis, Luke D; Nasmyth, Kim A

2017-09-19

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. We developed a non-fluorescent HaloTag ligand to discriminate the fluorescence recovery signal from labeling of newly synthesized Halo-tagged Scc1 protein (pulse-chase or pcFRAP). In cells where cohesin turnover is inactivated by deletion of WAPL, Scc1 can remain associated with chromatin throughout S phase. These findings suggest that cohesion might be generated by cohesin that is already bound to un-replicated DNA. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.
Establishment of a promoter-based chromatin architecture on recently replicated DNA can accommodate variable inter-nucleosome spacing.

PubMed

Fennessy, Ross T; Owen-Hughes, Tom

2016-09-06

Nucleosomes, the fundamental subunits of eukaryotic chromatin, are organized with respect to transcriptional start sites. A major challenge to the persistence of this organization is the disassembly of nucleosomes during DNA replication. Here, we use complimentary approaches to map the locations of nucleosomes on recently replicated DNA. We find that nucleosomes are substantially realigned with promoters during the minutes following DNA replication. As a result, the nucleosomal landscape is largely re-established before newly replicated chromosomes are partitioned into daughter cells and can serve as a platform for the re-establishment of gene expression programmes. When the supply of histones is disrupted through mutation of the chaperone Caf1, a promoter-based architecture is generated, but with increased inter-nucleosomal spacing. This indicates that the chromatin remodelling enzymes responsible for spacing nucleosomes are capable of organizing nucleosomes with a range of different linker DNA lengths. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.
RAD51 interconnects between DNA replication, DNA repair and immunity.

PubMed

Bhattacharya, Souparno; Srinivasan, Kalayarasan; Abdisalaam, Salim; Su, Fengtao; Raj, Prithvi; Dozmorov, Igor; Mishra, Ritu; Wakeland, Edward K; Ghose, Subroto; Mukherjee, Shibani; Asaithamby, Aroumougame

2017-05-05

RAD51, a multifunctional protein, plays a central role in DNA replication and homologous recombination repair, and is known to be involved in cancer development. We identified a novel role for RAD51 in innate immune response signaling. Defects in RAD51 lead to the accumulation of self-DNA in the cytoplasm, triggering a STING-mediated innate immune response after replication stress and DNA damage. In the absence of RAD51, the unprotected newly replicated genome is degraded by the exonuclease activity of MRE11, and the fragmented nascent DNA accumulates in the cytosol, initiating an innate immune response. Our data suggest that in addition to playing roles in homologous recombination-mediated DNA double-strand break repair and replication fork processing, RAD51 is also implicated in the suppression of innate immunity. Thus, our study reveals a previously uncharacterized role of RAD51 in initiating immune signaling, placing it at the hub of new interconnections between DNA replication, DNA repair, and immunity. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.
Regulatory Mechanisms That Prevent Re-initiation of DNA Replication Can Be Locally Modulated at Origins by Nearby Sequence Elements

PubMed Central

Richardson, Christopher D.; Li, Joachim J.

2014-01-01

Eukaryotic cells must inhibit re-initiation of DNA replication at each of the thousands of origins in their genome because re-initiation can generate genomic alterations with extraordinary frequency. To minimize the probability of re-initiation from so many origins, cells use a battery of regulatory mechanisms that reduce the activity of replication initiation proteins. Given the global nature of these mechanisms, it has been presumed that all origins are inhibited identically. However, origins re-initiate with diverse efficiencies when these mechanisms are disabled, and this diversity cannot be explained by differences in the efficiency or timing of origin initiation during normal S phase replication. This observation raises the possibility of an additional layer of replication control that can differentially regulate re-initiation at distinct origins. We have identified novel genetic elements that are necessary for preferential re-initiation of two origins and sufficient to confer preferential re-initiation on heterologous origins when the control of re-initiation is partially deregulated. The elements do not enhance the S phase timing or efficiency of adjacent origins and thus are specifically acting as re-initiation promoters (RIPs). We have mapped the two RIPs to ∼60 bp AT rich sequences that act in a distance- and sequence-dependent manner. During the induction of re-replication, Mcm2-7 reassociates both with origins that preferentially re-initiate and origins that do not, suggesting that the RIP elements can overcome a block to re-initiation imposed after Mcm2-7 associates with origins. Our findings identify a local level of control in the block to re-initiation. This local control creates a complex genomic landscape of re-replication potential that is revealed when global mechanisms preventing re-replication are compromised. Hence, if re-replication does contribute to genomic alterations, as has been speculated for cancer cells, some regions of the genome may be more susceptible to these alterations than others. PMID:24945837
Synchronization of DNA array replication kinetics

NASA Astrophysics Data System (ADS)

Manturov, Alexey O.; Grigoryev, Anton V.

2016-04-01

In the present work we discuss the features of the DNA replication kinetics at the case of multiplicity of simultaneously elongated DNA fragments. The interaction between replicated DNA fragments is carried out by free protons that appears at the every nucleotide attachment at the free end of elongated DNA fragment. So there is feedback between free protons concentration and DNA-polymerase activity that appears as elongation rate dependence. We develop the numerical model based on a cellular automaton, which can simulate the elongation stage (growth of DNA strands) for DNA elongation process with conditions pointed above and we study the possibility of the DNA polymerases movement synchronization. The results obtained numerically can be useful for DNA polymerase movement detection and visualization of the elongation process in the case of massive DNA replication, eg, under PCR condition or for DNA "sequencing by synthesis" sequencing devices evaluation.
Development of a Novel Anti-HIV-1 Agent from within: Effect of Chimeric Vpr-Containing Protease Cleavage Site Residues on Virus Replication

NASA Astrophysics Data System (ADS)

Serio, D.; Rizvi, T. A.; Cartas, M.; Kalyanaraman, V. S.; Weber, I. T.; Koprowski, H.; Srinivasan, A.

1997-04-01

Effective antiviral agents will be of great value in controlling virus replication and delaying the onset of HIV-1-related disease symptoms. Current therapy involves the use of antiviral agents that target the enzymatic functions of the virus, resulting in the emergence of resistant viruses to these agents, thus lowering their effectiveness. To overcome this problem, we have considered the idea of developing novel agents from within HIV-1 as inhibitors of virus replication. The specificity of the Vpr protein for the HIV-1 virus particle makes it an attractive molecule for the development of antiviral agents targeting the events associated with virus maturation. We have generated chimeric Vpr proteins containing HIV-1-specific sequences added to the C terminus of Vpr. These sequences correspond to nine cleavage sites of the Gag and Gag-Pol precursors of HIV-1. The chimeric Vpr constructs were introduced into HIV-1 proviral DNA to assess their effect on virus infectivity using single- and multiple-round replication assays. The virus particles generated exhibited a variable replication pattern depending on the protease cleavage site used as a fusion partner. Interestingly, the chimeric Vpr containing the cleavage sequences from the junction of p24 and p2, 24/2, completely abolished virus infectivity. These results show that chimeric proteins generated from within HIV-1 have the ability to suppress HIV-1 replication and make ideal agents for gene therapy or intracellular immunization to treat HIV-1 infection.
Universal Sequence Replication, Reversible Polymerization and Early Functional Biopolymers: A Model for the Initiation of Prebiotic Sequence Evolution

PubMed Central

Walker, Sara Imari; Grover, Martha A.; Hud, Nicholas V.

2012-01-01

Many models for the origin of life have focused on understanding how evolution can drive the refinement of a preexisting enzyme, such as the evolution of efficient replicase activity. Here we present a model for what was, arguably, an even earlier stage of chemical evolution, when polymer sequence diversity was generated and sustained before, and during, the onset of functional selection. The model includes regular environmental cycles (e.g. hydration-dehydration cycles) that drive polymers between times of replication and functional activity, which coincide with times of different monomer and polymer diffusivity. Template-directed replication of informational polymers, which takes place during the dehydration stage of each cycle, is considered to be sequence-independent. New sequences are generated by spontaneous polymer formation, and all sequences compete for a finite monomer resource that is recycled via reversible polymerization. Kinetic Monte Carlo simulations demonstrate that this proposed prebiotic scenario provides a robust mechanism for the exploration of sequence space. Introduction of a polymer sequence with monomer synthetase activity illustrates that functional sequences can become established in a preexisting pool of otherwise non-functional sequences. Functional selection does not dominate system dynamics and sequence diversity remains high, permitting the emergence and spread of more than one functional sequence. It is also observed that polymers spontaneously form clusters in simulations where polymers diffuse more slowly than monomers, a feature that is reminiscent of a previous proposal that the earliest stages of life could have been defined by the collective evolution of a system-wide cooperation of polymer aggregates. Overall, the results presented demonstrate the merits of considering plausible prebiotic polymer chemistries and environments that would have allowed for the rapid turnover of monomer resources and for regularly varying monomer/polymer diffusivities. PMID:22493682
Plasmid P1 replication: negative control by repeated DNA sequences.

PubMed Central

Chattoraj, D; Cordes, K; Abeles, A

1984-01-01

The incompatibility locus, incA, of the unit-copy plasmid P1 is contained within a fragment that is essentially a set of nine 19-base-pair repeats. One or more copies of the fragment destabilizes the plasmid when present in trans. Here we show that extra copies of incA interfere with plasmid DNA replication and that a deletion of most of incA increases plasmid copy number. Thus, incA is not essential for replication but is required for its control. When cloned in a high-copy-number vector, pieces of the incA fragment that each contain only three repeats destabilize P1 plasmids efficiently. This result makes it unlikely that incA specifies a regulatory product. Our in vivo results suggest that the repeating DNA sequence itself negatively controls replication by titrating a P1-determined protein, RepA, that is essential for replication. Consistent with this hypothesis is the observation that the RepA protein binds to the incA fragment in vitro. Images PMID:6387706
Topological impact of noncanonical DNA structures on Klenow fragment of DNA polymerase.

PubMed

Takahashi, Shuntaro; Brazier, John A; Sugimoto, Naoki

2017-09-05

Noncanonical DNA structures that stall DNA replication can cause errors in genomic DNA. Here, we investigated how the noncanonical structures formed by sequences in genes associated with a number of diseases impacted DNA polymerization by the Klenow fragment of DNA polymerase. Replication of a DNA sequence forming an i-motif from a telomere, hypoxia-induced transcription factor, and an insulin-linked polymorphic region was effectively inhibited. On the other hand, replication of a mixed-type G-quadruplex (G4) from a telomere was less inhibited than that of the antiparallel type or parallel type. Interestingly, the i-motif was a better inhibitor of replication than were mixed-type G4s or hairpin structures, even though all had similar thermodynamic stabilities. These results indicate that both the stability and topology of structures formed in DNA templates impact the processivity of a DNA polymerase. This suggests that i-motif formation may trigger genomic instability by stalling the replication of DNA, causing intractable diseases.
Topological impact of noncanonical DNA structures on Klenow fragment of DNA polymerase

PubMed Central

Takahashi, Shuntaro; Brazier, John A.; Sugimoto, Naoki

2017-01-01

Noncanonical DNA structures that stall DNA replication can cause errors in genomic DNA. Here, we investigated how the noncanonical structures formed by sequences in genes associated with a number of diseases impacted DNA polymerization by the Klenow fragment of DNA polymerase. Replication of a DNA sequence forming an i-motif from a telomere, hypoxia-induced transcription factor, and an insulin-linked polymorphic region was effectively inhibited. On the other hand, replication of a mixed-type G-quadruplex (G4) from a telomere was less inhibited than that of the antiparallel type or parallel type. Interestingly, the i-motif was a better inhibitor of replication than were mixed-type G4s or hairpin structures, even though all had similar thermodynamic stabilities. These results indicate that both the stability and topology of structures formed in DNA templates impact the processivity of a DNA polymerase. This suggests that i-motif formation may trigger genomic instability by stalling the replication of DNA, causing intractable diseases. PMID:28827350
Medium-chain triglyceride as an alternative of in-feed colistin sulfate to improve growth performance and intestinal microbial environment in newly weaned pigs.

PubMed

Yen, Hung-Che; Lai, Wei-Kang; Lin, Chuan-Shun; Chiang, Shu-Hsing

2015-01-01

Five hundred and twenty-eight newly weaned pigs were given four treatments, with eight replicates per treatment. Sixteen to 18 pigs were assigned per replicate and were fed diets supplemented with 0 or 3% medium-chain triglyceride (MCT) and 0 or 40 ppm colistin sulfate (CS) in a 2 × 2 factorial arrangement for 2 weeks. The results showed that dietary supplementation with MCT improved the gain-to-feed ratio during days 3-7 and in the overall period (P < 0.05). Dietary supplementation with MCT decreased coliforms counts (C) in colon and rectum content (P < 0.05). Dietary supplementation with CS decreased C and lactic acid bacteria plus C counts (L + C) in cecum (P < 0.05), and C, L + C (P < 0.01) and ratio of L and C (P < 0.05) in colon and rectum contents. The lack of interactions between MCT and CS indicates different modes of action and additive effects between the two supplementations. In conclusion, supplementation with MCT in diet with or without CS could improve the intestinal microbial environment and the feed utilization efficiency of newly weaned pigs. © 2014 Japanese Society of Animal Science.
Sequence selection by dynamical symmetry breaking in an autocatalytic binary polymer model

NASA Astrophysics Data System (ADS)

Fellermann, Harold; Tanaka, Shinpei; Rasmussen, Steen

2017-12-01

Template-directed replication of nucleic acids is at the essence of all living beings and a major milestone for any origin of life scenario. We present an idealized model of prebiotic sequence replication, where binary polymers act as templates for their autocatalytic replication, thereby serving as each others reactants and products in an intertwined molecular ecology. Our model demonstrates how autocatalysis alters the qualitative and quantitative system dynamics in counterintuitive ways. Most notably, numerical simulations reveal a very strong intrinsic selection mechanism that favors the appearance of a few population structures with highly ordered and repetitive sequence patterns when starting from a pool of monomers. We demonstrate both analytically and through simulation how this "selection of the dullest" is caused by continued symmetry breaking through random fluctuations in the transient dynamics that are amplified by autocatalysis and eventually propagate to the population level. The impact of these observations on related prebiotic mathematical models is discussed.
[Replication of Streptomyces plasmids: the DNA nucleotide sequence of plasmid pSB 24.2].

PubMed

Bolotin, A P; Sorokin, A V; Aleksandrov, N N; Danilenko, V N; Kozlov, Iu I

1985-11-01

The nucleotide sequence of DNA in plasmid pSB 24.2, a natural deletion derivative of plasmid pSB 24.1 isolated from S. cyanogenus was studied. The plasmid amounted by its size to 3706 nucleotide pairs. The G-C composition was equal to 73 per cent. The analysis of the DNA structure in plasmid pSB 24.2 revealed the protein-encoding sequence of DNA, the continuity of which was significant for replication of the plasmid containing more than 1300 nucleotide pairs. The analysis also revealed two A-T-rich areas of DNA, the G-C composition of which was less than 55 per cent and a DNA area with a branched pin structure. The results may be of value in investigation of plasmid replication in actinomycetes and experimental cloning of DNA with this plasmid as a vector.
Genetic characterization of avian metapneumovirus subtype C isolated from pheasants in a live bird market.

PubMed

Lee, Eun ho; Song, Min-Suk; Shin, Jin-Young; Lee, Young-Min; Kim, Chul-Joong; Lee, Young Sik; Kim, Hyunggee; Choi, Young Ki

2007-09-01

Complete nucleotide sequences of two avian metapneumoviruses (aMPV), designated PL-1 and PL-2, were isolated from pheasants, revealing novel sequences of the first aMPV to be fully sequenced in Korea. The complete genome of both PL-1 and PL-2 was composed of 13,170 nucleotides. Phylogenetic analysis revealed that PL-1 belonged to aMPV subtype C, sharing higher homology in deduced amino acid sequence identities with hMPV, rather than with aMPV subtypes A and B. Replication of PL-1 in experimentally re-infected pheasants was confirmed by reverse transcription (RT)-polymerase chain reaction (PCR). Chickens and mice were experimentally inoculated with PL-1 to test the replication potential of PL-1 in other species. Although one specimen from the nasal turbinates of an inoculated chicken showed a slight trace of viral replication at 3 days post-infection (dpi), all of the infected mice were negative for aMPV by RT-PCR throughout the experiment, suggesting that PL-1 does not readily infect mammals. This is the first report of the isolation and complete genomic sequence of aMPV subtype C originating from pheasants.
Role of Histone Acetylation in the Assembly and Modulation of Chromatin Structures

PubMed Central

Annunziato, Anthony T.; Hansen, Jeffrey C.

2000-01-01

The acetylation of the core histone N-terminal “tail” domains is now recognized as a highly conserved mechanism for regulating chromatin functional states. The following article examines possible roles of acetylation in two critically important cellular processes: replication-coupled nucleosome assembly, and reversible transitions in chromatin higher order structure. After a description of the acetylation of newly synthesized histones, and of the likely acetyltransferases involved, an overview of histone octamer assembly is presented. Our current understanding of the factors thought to assemble chromatin in vivo is then described. Genetic and biochemical investigations of the function the histone tails, and their acetylation, in nucleosome assembly are detailed, followed by an analysis of the importance of histone deacetylation in the maturation of newly replicated chromatin. In the final section the involvement of the histone tail domains in chromatin higher order structures is addressed, along with the role of histone acetylation in chromatin folding. Suggestions for future research are offered in the concluding remarks. PMID:11097424
Reduced virus replication, proinflammatory cytokine production, and delayed macrophage cell death in human PBMCs infected with the newly discovered Bundibugyo ebolavirus relative to Zaire ebolavirus.

PubMed

Gupta, Manisha; Goldsmith, Cynthia S; Metcalfe, Maureen G; Spiropoulou, Christina F; Spipopoulou, Christina F; Rollin, Pierre E

2010-06-20

Bundibugyo ebolavirus is a newly identified Ebolavirus species. The virus was responsible for a recent hemorrhagic fever outbreak in Uganda with an approximate 30% case fatality rate. In this study, we compared the pathogenesis of Bundibugyo with highly lethal Zaire Ebolavirus by using in vitro human PBMCs. We found that PBMCs infected with Bundibugyo ebolaviruses resulted in 1 to 2 log lower virus yields compared to Zaire ebolavirus and produced 2- to 10-fold lower levels of TNF-alpha, MCP-1, IL-1beta, MIP1-alpha and IL-10 than PBMCs infected with Zaire ebolavirus. In addition, flow cytometric studies have shown lower levels and delay of the macrophage cell death in Bundibugyo ebolavirus compared to Zaire ebolavirus infection. The findings of slower Bundibugyo ebolavirus replication, lower production of proinflammatory cytokines and delay in macrophage cell death provide insight into the basis of the lower case fatality observed with Bundibugyo ebolavirus. Published by Elsevier Inc.

Minichromosome assembly of non-integrated plasmid DNA transfected into mammalian cells.

PubMed Central

Reeves, R; Gorman, C M; Howard, B

1985-01-01

The nucleoprotein structures formed on various plasmid expression vectors transfected into mammalian cells by both the calcium phosphate and DEAE-dextran methods have been studied. We demonstrate by a variety of means that mammalian cells are capable of rapidly assembling non-integrated circular plasmids (both replicating and non-replicating) into typical "minichromosomes" containing nucleosomes with a 190 bp repetitive spacing. Treatment of recipient cells with sodium butyrate for a short period of time (12-16 h) immediately following transfection markedly increased the DNase I digestion sensitivity of the newly assembled plasmid chromatin. Furthermore, minichromosomes isolated from such butyrate-treated cells are depleted in histone H1 and contain highly acetylated forms of histone H4. These findings are entirely consistent with our earlier speculation (Gorman et al., Nucleic Acids Res. 11, 1044; 1983) that appropriate butyrate treatment might stimulate transient expression of newly transfected genes by facilitating their assembly into an "active" type of chromatin structure. Images PMID:3859838
Adaptive evolution of newly emerged micro-RNA genes in Drosophila.

PubMed

Lu, Jian; Fu, Yonggui; Kumar, Supriya; Shen, Yang; Zeng, Kai; Xu, Anlong; Carthew, Richard; Wu, Chung-I

2008-05-01

How often micro-RNA (miRNA) genes emerged and how fast they evolved soon after their emergence are some of the central questions in the evolution of miRNAs. Because most known miRNA genes are ancient and highly conserved, these questions can be best answered by identifying newly emerged miRNA genes. Among the 78 miRNA genes in Drosophila reported before 2007, only 5 are confirmed to be newly emerged in the genus (although many more can be found in the newly reported data set; e.g., Ruby et al. 2007; Stark et al. 2007; Lu et al. 2008). These new miRNA genes have undergone numerous changes, even in the normally invariant mature sequences. Four of them (the miR-310/311/312/313 cluster, denoted miR-310s) were duplicated from other conserved miRNA genes. The fifth one (miR-303) appears to be a very young gene, originating de novo from a non-miRNA sequence recently. We sequenced these 5 miRNA genes and their neighboring regions from a worldwide collection of Drosophila melanogaster lines. The levels of divergence and polymorphism in these miRNA genes, vis-à-vis those of the neighboring DNA sequences, suggest that these 5 genes are evolving adaptively. Furthermore, the polymorphism pattern of miR-310s in D. melanogaster is indicative of hitchhiking under positive selection. Thus, a large number of adaptive changes over a long period of time may be essential for the evolution of newly emerged miRNA genes.
New multifunctional Escherichia coli-Streptomyces shuttle vectors allowing blue-white screening on XGal plates.

PubMed

Wehmeier, U F

1995-11-07

Four new shuttle vectors for Escherichia coli (Ec) and Streptomyces, pUWL218, pUWL219, pUWL-SK and pUWL-KS, which permit recognition of recombinant (re-) plasmids on XGal plates in Ec, were constructed. These vectors contain the replication functions of the Streptomyces wide-host-range multicopy plasmid pIJ101, the tsr gene conferring resistance to thiostrepton in Streptomyces, the ColEI origin of replication from the pUC plasmids for replication in Ec and the bla gene conferring resistance to ampicillin in Ec. They possess multiple cloning sites with a number of unique restriction sites and allow direct sequencing of re-derivatives using the pUC sequencing primers.
A DNA sequence element that advances replication origin activation time in Saccharomyces cerevisiae.

PubMed

Pohl, Thomas J; Kolor, Katherine; Fangman, Walton L; Brewer, Bonita J; Raghuraman, M K

2013-11-06

Eukaryotic origins of DNA replication undergo activation at various times in S-phase, allowing the genome to be duplicated in a temporally staggered fashion. In the budding yeast Saccharomyces cerevisiae, the activation times of individual origins are not intrinsic to those origins but are instead governed by surrounding sequences. Currently, there are two examples of DNA sequences that are known to advance origin activation time, centromeres and forkhead transcription factor binding sites. By combining deletion and linker scanning mutational analysis with two-dimensional gel electrophoresis to measure fork direction in the context of a two-origin plasmid, we have identified and characterized a 19- to 23-bp and a larger 584-bp DNA sequence that are capable of advancing origin activation time.
Experience of targeted Usher exome sequencing as a clinical test

PubMed Central

Besnard, Thomas; García-García, Gema; Baux, David; Vaché, Christel; Faugère, Valérie; Larrieu, Lise; Léonard, Susana; Millan, Jose M; Malcolm, Sue; Claustres, Mireille; Roux, Anne-Françoise

2014-01-01

We show that massively parallel targeted sequencing of 19 genes provides a new and reliable strategy for molecular diagnosis of Usher syndrome (USH) and nonsyndromic deafness, particularly appropriate for these disorders characterized by a high clinical and genetic heterogeneity and a complex structure of several of the genes involved. A series of 71 patients including Usher patients previously screened by Sanger sequencing plus newly referred patients was studied. Ninety-eight percent of the variants previously identified by Sanger sequencing were found by next-generation sequencing (NGS). NGS proved to be efficient as it offers analysis of all relevant genes which is laborious to reach with Sanger sequencing. Among the 13 newly referred Usher patients, both mutations in the same gene were identified in 77% of cases (10 patients) and one candidate pathogenic variant in two additional patients. This work can be considered as pilot for implementing NGS for genetically heterogeneous diseases in clinical service. PMID:24498627
Novel cis-acting replication element in the adeno-associated virus type 2 genome is involved in amplification of integrated rep-cap sequences.

PubMed

Nony, P; Tessier, J; Chadeuf, G; Ward, P; Giraud, A; Dugast, M; Linden, R M; Moullier, P; Salvetti, A

2001-10-01

This study identifies a region of the adeno-associated virus type 2 (AAV-2) rep gene (nucleotides 190 to 540 of wild-type AAV-2) as a cis-acting Rep-dependent element able to promote the replication of transiently transfected plasmids. This viral element is also shown to be involved in the amplification of integrated sequences in the presence of adenovirus and Rep proteins.
A quantitative and high-throughput assay of human papillomavirus DNA replication.

PubMed

Gagnon, David; Fradet-Turcotte, Amélie; Archambault, Jacques

2015-01-01

Replication of the human papillomavirus (HPV) double-stranded DNA genome is accomplished by the two viral proteins E1 and E2 in concert with host DNA replication factors. HPV DNA replication is an established model of eukaryotic DNA replication and a potential target for antiviral therapy. Assays to measure the transient replication of HPV DNA in transfected cells have been developed, which rely on a plasmid carrying the viral origin of DNA replication (ori) together with expression vectors for E1 and E2. Replication of the ori-plasmid is typically measured by Southern blotting or PCR analysis of newly replicated DNA (i.e., DpnI digested DNA) several days post-transfection. Although extremely valuable, these assays have been difficult to perform in a high-throughput and quantitative manner. Here, we describe a modified version of the transient DNA replication assay that circumvents these limitations by incorporating a firefly luciferase expression cassette in cis of the ori. Replication of this ori-plasmid by E1 and E2 results in increased levels of firefly luciferase activity that can be accurately quantified and normalized to those of Renilla luciferase expressed from a control plasmid, thus obviating the need for DNA extraction, digestion, and analysis. We provide a detailed protocol for performing the HPV type 31 DNA replication assay in a 96-well plate format suitable for small-molecule screening and EC50 determinations. The quantitative and high-throughput nature of the assay should greatly facilitate the study of HPV DNA replication and the identification of inhibitors thereof.
G-quadruplex-interacting compounds alter latent DNA replication and episomal persistence of KSHV.

PubMed

Madireddy, Advaitha; Purushothaman, Pravinkumar; Loosbroock, Christopher P; Robertson, Erle S; Schildkraut, Carl L; Verma, Subhash C

2016-05-05

Kaposi's sarcoma associated herpesvirus (KSHV) establishes life-long latent infection by persisting as an extra-chromosomal episome in the infected cells and by maintaining its genome in dividing cells. KSHV achieves this by tethering its epigenome to the host chromosome by latency associated nuclear antigen (LANA), which binds in the terminal repeat (TR) region of the viral genome. Sequence analysis of the TR, a GC-rich DNA element, identified several potential Quadruplex G-Rich Sequences (QGRS). Since quadruplexes have the tendency to obstruct DNA replication, we used G-quadruplex stabilizing compounds to examine their effect on latent DNA replication and the persistence of viral episomes. Our results showed that these G-quadruplex stabilizing compounds led to the activation of dormant origins of DNA replication, with preferential bi-directional pausing of replications forks moving out of the TR region, implicating the role of the G-rich TR in the perturbation of episomal DNA replication. Over time, treatment with PhenDC3 showed a loss of viral episomes in the infected cells. Overall, these data show that G-quadruplex stabilizing compounds retard the progression of replication forks leading to a reduction in DNA replication and episomal maintenance. These results suggest a potential role for G-quadruplex stabilizers in the treatment of KSHV-associated diseases. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.
Replicative Intermediates of Human Papillomavirus Type 11 in Laryngeal Papillomas: Site of Replication Initiation and Direction of Replication

NASA Astrophysics Data System (ADS)

Auborn, K. J.; Little, R. D.; Platt, T. H. K.; Vaccariello, M. A.; Schildkraut, C. L.

1994-07-01

We have examined the structures of replication intermediates from the human papillomavirus type 11 genome in DNA extracted from papilloma lesions (laryngeal papillomas). The sites of replication initiation and termination utilized in vivo were mapped by using neutral/neutral and neutral/alkaline two-dimensional agarose gel electrophoresis methods. Initiation of replication was detected in or very close to the upstream regulatory region (URR; the noncoding, regulatory sequences upstream of the open reading frames in the papillomavirus genome). We also show that replication forks proceed bidirectionally from the origin and converge 180circ opposite the URR. These results demonstrate the feasibility of analysis of replication of viral genomes directly from infected tissue.
Origin Replication Complex Binding, Nucleosome Depletion Patterns, and a Primary Sequence Motif Can Predict Origins of Replication in a Genome with Epigenetic Centromeres

PubMed Central

Tsai, Hung-Ji; Baller, Joshua A.; Liachko, Ivan; Koren, Amnon; Burrack, Laura S.; Hickman, Meleah A.; Thevandavakkam, Mathuravani A.; Rusche, Laura N.

2014-01-01

ABSTRACT Origins of DNA replication are key genetic elements, yet their identification remains elusive in most organisms. In previous work, we found that centromeres contain origins of replication (ORIs) that are determined epigenetically in the pathogenic yeast Candida albicans. In this study, we used origin recognition complex (ORC) binding and nucleosome occupancy patterns in Saccharomyces cerevisiae and Kluyveromyces lactis to train a machine learning algorithm to predict the position of active arm (noncentromeric) origins in the C. albicans genome. The model identified bona fide active origins as determined by the presence of replication intermediates on nondenaturing two-dimensional (2D) gels. Importantly, these origins function at their native chromosomal loci and also as autonomously replicating sequences (ARSs) on a linear plasmid. A “mini-ARS screen” identified at least one and often two ARS regions of ≥100 bp within each bona fide origin. Furthermore, a 15-bp AC-rich consensus motif was associated with the predicted origins and conferred autonomous replicating activity to the mini-ARSs. Thus, while centromeres and the origins associated with them are epigenetic, arm origins are dependent upon critical DNA features, such as a binding site for ORC and a propensity for nucleosome exclusion. PMID:25182328
The extent of sequence complementarity correlates with the potency of cellular miRNA-mediated restriction of HIV-1

PubMed Central

Houzet, Laurent; Klase, Zachary; Yeung, Man Lung; Wu, Annie; Le, Shu-Yun; Quiñones, Mariam; Jeang, Kuan-Teh

2012-01-01

MicroRNAs (miRNAs) are 22-nt non-coding RNAs involved in the regulation of cellular gene expression and potential cellular defense against viral infection. Using in silico analyses, we predicted target sites for 22 human miRNAs in the HIV genome. Transfection experiments using synthetic miRNAs showed that five of these miRNAs capably decreased HIV replication. Using one of these five miRNAs, human miR-326 as an example, we demonstrated that the degree of complementarity between the predicted viral sequence and cellular miR-326 correlates, in a Dicer-dependent manner, with the potency of miRNA-mediated restriction of viral replication. Antagomirs to miR-326 that knocked down this cell endogenous miRNA increased HIV-1 replication in cells, suggesting that miR-326 is physiologically functional in moderating HIV-1 replication in human cells. PMID:23042677
Autonomous replication of nucleic acids by polymerization/nicking enzyme/DNAzyme cascades for the amplified detection of DNA and the aptamer-cocaine complex.

PubMed

Wang, Fuan; Freage, Lina; Orbach, Ron; Willner, Itamar

2013-09-03

The progressive development of amplified DNA sensors and aptasensors using replication/nicking enzymes/DNAzyme machineries is described. The sensing platforms are based on the tailoring of a DNA template on which the recognition of the target DNA or the formation of the aptamer-substrate complex trigger on the autonomous isothermal replication/nicking processes and the displacement of a Mg(2+)-dependent DNAzyme that catalyzes the generation of a fluorophore-labeled nucleic acid acting as readout signal for the analyses. Three different DNA sensing configurations are described, where in the ultimate configuration the target sequence is incorporated into a nucleic acid blocker structure associated with the sensing template. The target-triggered isothermal autonomous replication/nicking process on the modified template results in the formation of the Mg(2+)-dependent DNAzyme tethered to a free strand consisting of the target sequence. This activates additional template units for the nucleic acid self-replication process, resulting in the ultrasensitive detection of the target DNA (detection limit 1 aM). Similarly, amplified aptamer-based sensing platforms for cocaine are developed along these concepts. The modification of the cocaine-detection template by the addition of a nucleic acid sequence that enables the autonomous secondary coupled activation of a polymerization/nicking machinery and DNAzyme generation path leads to an improved analysis of cocaine (detection limit 10 nM).
Organization of the origins of replication of the chromosomes of Mycobacterium smegmatis, Mycobacterium leprae and Mycobacterium tuberculosis and isolation of a functional origin from M. smegmatis.

PubMed

Salazar, L; Fsihi, H; de Rossi, E; Riccardi, G; Rios, C; Cole, S T; Takiff, H E

1996-04-01

The genus Mycobacterium is composed of species with widely differing growth rates ranging from approximately three hours in Mycobacterium smegmatis to two weeks in Mycobacterium leprae. As DNA replication is coupled to cell duplication, it may be regulated by common mechanisms. The chromosomal regions surrounding the origins of DNA replication from M. smegmatis, M. tuberculosis, and M. leprae have been sequenced, and show very few differences. The gene order, rnpA-rpmH-dnaA-dnaN-recF-orf-gyrB-gyrA, is the same as in other Gram-positive organisms. Although the general organization in M. smegmatis is very similar to that of Streptomyces spp., a closely related genus, M. tuberculosis and M. leprae differ as they lack an open reading frame, between dnaN and recF, which is similar to the gnd gene of Escherichia coli. Within the three mycobacterial species, there is extensive sequence conservation in the intergenic regions flanking dnaA, but more variation from the consensus DnaA box sequence was seen than in other bacteria. By means of subcloning experiments, the putative chromosomal origin of replication of M. smegmatis, containing the dnaA-dnaN region, was shown to promote autonomous replication in M. smegmatis, unlike the corresponding regions from M. tuberculosis or M. leprae.
RNA-dependent RNA polymerase of hepatitis C virus binds to its coding region RNA stem-loop structure, 5BSL3.2, and its negative strand.

PubMed

Kanamori, Hiroshi; Yuhashi, Kazuhito; Ohnishi, Shin; Koike, Kazuhiko; Kodama, Tatsuhiko

2010-05-01

The hepatitis C virus NS5B RNA-dependent RNA polymerase (RdRp) is a key enzyme involved in viral replication. Interaction between NS5B RdRp and the viral RNA sequence is likely to be an important step in viral RNA replication. The C-terminal half of the NS5B-coding sequence, which contains the important cis-acting replication element, has been identified as an NS5B-binding sequence. In the present study, we confirm the specific binding of NS5B to one of the RNA stem-loop structures in the region, 5BSL3.2. In addition, we show that NS5B binds to the complementary strand of 5BSL3.2 (5BSL3.2N). The bulge structure of 5BSL3.2N was shown to be indispensable for tight binding to NS5B. In vitro RdRp activity was inhibited by 5BSL3.2N, indicating the importance of the RNA element in the polymerization by RdRp. These results suggest the involvement of the RNA stem-loop structure of the negative strand in the replication process.
Mapping DNA polymerase errors by single-molecule sequencing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, David F.; Lu, Jenny; Chang, Seungwoo

Genomic integrity is compromised by DNA polymerase replication errors, which occur in a sequence-dependent manner across the genome. Accurate and complete quantification of a DNA polymerase's error spectrum is challenging because errors are rare and difficult to detect. We report a high-throughput sequencing assay to map in vitro DNA replication errors at the single-molecule level. Unlike previous methods, our assay is able to rapidly detect a large number of polymerase errors at base resolution over any template substrate without quantification bias. To overcome the high error rate of high-throughput sequencing, our assay uses a barcoding strategy in which each replicationmore » product is tagged with a unique nucleotide sequence before amplification. Here, this allows multiple sequencing reads of the same product to be compared so that sequencing errors can be found and removed. We demonstrate the ability of our assay to characterize the average error rate, error hotspots and lesion bypass fidelity of several DNA polymerases.« less
Mapping DNA polymerase errors by single-molecule sequencing

DOE PAGES

Lee, David F.; Lu, Jenny; Chang, Seungwoo; ...

2016-05-16

Genomic integrity is compromised by DNA polymerase replication errors, which occur in a sequence-dependent manner across the genome. Accurate and complete quantification of a DNA polymerase's error spectrum is challenging because errors are rare and difficult to detect. We report a high-throughput sequencing assay to map in vitro DNA replication errors at the single-molecule level. Unlike previous methods, our assay is able to rapidly detect a large number of polymerase errors at base resolution over any template substrate without quantification bias. To overcome the high error rate of high-throughput sequencing, our assay uses a barcoding strategy in which each replicationmore » product is tagged with a unique nucleotide sequence before amplification. Here, this allows multiple sequencing reads of the same product to be compared so that sequencing errors can be found and removed. We demonstrate the ability of our assay to characterize the average error rate, error hotspots and lesion bypass fidelity of several DNA polymerases.« less
Maintaining replication origins in the face of genomic change.

PubMed

Di Rienzi, Sara C; Lindstrom, Kimberly C; Mann, Tobias; Noble, William S; Raghuraman, M K; Brewer, Bonita J

2012-10-01

Origins of replication present a paradox to evolutionary biologists. As a collection, they are absolutely essential genomic features, but individually are highly redundant and nonessential. It is therefore difficult to predict to what extent and in what regard origins are conserved over evolutionary time. Here, through a comparative genomic analysis of replication origins and chromosomal replication patterns in the budding yeasts Saccharomyces cerevisiae and Lachancea waltii, we assess to what extent replication origins survived genomic change produced from 150 million years of evolution. We find that L. waltii origins exhibit a core consensus sequence and nucleosome occupancy pattern highly similar to those of S. cerevisiae origins. We further observe that the overall progression of chromosomal replication is similar between L. waltii and S. cerevisiae. Nevertheless, few origins show evidence of being conserved in location between the two species. Among the conserved origins are those surrounding centromeres and adjacent to histone genes, suggesting that proximity to an origin may be important for their regulation. We conclude that, over evolutionary time, origins maintain sequence, structure, and regulation, but are continually being created and destroyed, with the result that their locations are generally not conserved.
Maintaining replication origins in the face of genomic change

PubMed Central

Di Rienzi, Sara C.; Lindstrom, Kimberly C.; Mann, Tobias; Noble, William S.; Raghuraman, M.K.; Brewer, Bonita J.

2012-01-01

Origins of replication present a paradox to evolutionary biologists. As a collection, they are absolutely essential genomic features, but individually are highly redundant and nonessential. It is therefore difficult to predict to what extent and in what regard origins are conserved over evolutionary time. Here, through a comparative genomic analysis of replication origins and chromosomal replication patterns in the budding yeasts Saccharomyces cerevisiae and Lachancea waltii, we assess to what extent replication origins survived genomic change produced from 150 million years of evolution. We find that L. waltii origins exhibit a core consensus sequence and nucleosome occupancy pattern highly similar to those of S. cerevisiae origins. We further observe that the overall progression of chromosomal replication is similar between L. waltii and S. cerevisiae. Nevertheless, few origins show evidence of being conserved in location between the two species. Among the conserved origins are those surrounding centromeres and adjacent to histone genes, suggesting that proximity to an origin may be important for their regulation. We conclude that, over evolutionary time, origins maintain sequence, structure, and regulation, but are continually being created and destroyed, with the result that their locations are generally not conserved. PMID:22665441
Structure and Function of the N-Terminal Domain of the Vesicular Stomatitis Virus RNA Polymerase

PubMed Central

Qiu, Shihong; Ogino, Minako; Luo, Ming

2015-01-01

ABSTRACT Viruses have various mechanisms to duplicate their genomes and produce virus-specific mRNAs. Negative-strand RNA viruses encode their own polymerases to perform each of these processes. For the nonsegmented negative-strand RNA viruses, the polymerase is comprised of the large polymerase subunit (L) and the phosphoprotein (P). L proteins from members of the Rhabdoviridae, Paramyxoviridae, and Filoviridae share sequence and predicted secondary structure homology. Here, we present the structure of the N-terminal domain (conserved region I) of the L protein from a rhabdovirus, vesicular stomatitis virus, at 1.8-Å resolution. The strictly and strongly conserved residues in this domain cluster in a single area of the protein. Serial mutation of these residues shows that many of the amino acids are essential for viral transcription but not for mRNA capping. Three-dimensional alignments show that this domain shares structural homology with polymerases from other viral families, including segmented negative-strand RNA and double-stranded RNA (dsRNA) viruses. IMPORTANCE Negative-strand RNA viruses include a diverse set of viral families that infect animals and plants, causing serious illness and economic impact. The members of this group of viruses share a set of functionally conserved proteins that are essential to their replication cycle. Among this set of proteins is the viral polymerase, which performs a unique set of reactions to produce genome- and subgenome-length RNA transcripts. In this article, we study the polymerase of vesicular stomatitis virus, a member of the rhabdoviruses, which has served in the past as a model to study negative-strand RNA virus replication. We have identified a site in the N-terminal domain of the polymerase that is essential to viral transcription and that shares sequence homology with members of the paramyxoviruses and the filoviruses. Newly identified sites such as that described here could prove to be useful targets in the design of new therapeutics against negative-strand RNA viruses. PMID:26512087
Rare, low frequency, and common coding variants in CHRNA5 and their contribution to nicotine dependence in European and African Americans

PubMed Central

Olfson, Emily; Saccone, Nancy L.; Johnson, Eric O.; Chen, Li-Shiun; Culverhouse, Robert; Doheny, Kimberly; Foltz, Steven M.; Fox, Louis; Gogarten, Stephanie M.; Hartz, Sarah; Hetrick, Kurt; Laurie, Cathy C.; Marosy, Beth; Amin, Najaf; Arnett, Donna; Barr, R. Graham; Bartz, Traci M.; Bertelsen, Sarah; Borecki, Ingrid B.; Brown, Michael R.; Chasman, Daniel I.; van Duijn, Cornelia M.; Feitosa, Mary F.; Fox, Ervin R.; Franceschini, Nora; Franco, Oscar H.; Grove, Megan L.; Guo, Xiuqing; Hofman, Albert; Kardia, Sharon L.R.; Morrison, Alanna C.; Musani, Solomon K.; Psaty, Bruce M.; Rao, D.C.; Reiner, Alex P.; Rice, Kenneth; Ridker, Paul M.; Rose, Lynda M.; Schick, Ursula M.; Schwander, Karen; Uitterlinden, Andre G.; Vojinovic, Dina; Wang, Jen-Chyong; Ware, Erin B.; Wilson, Gregory; Yao, Jie; Zhao, Wei; Breslau, Naomi; Hatsukami, Dorothy; Stitzel, Jerry A.; Rice, John; Goate, Alison; Bierut, Laura J.

2015-01-01

The common nonsynonymous variant rs16969968 in the α5 nicotinic receptor subunit gene (CHRNA5) is the strongest genetic risk factor for nicotine dependence in European Americans and contributes to risk in African Americans. To comprehensively examine whether other CHRNA5 coding variation influences nicotine dependence risk, we performed targeted sequencing on 1582 nicotine dependent cases (Fagerström Test for Nicotine Dependence score≥4) and 1238 non-dependent controls, with independent replication of common and low frequency variants using 12 studies with exome chip data. Nicotine dependence was examined using logistic regression with individual common variants (MAF≥0.05), aggregate low frequency variants (0.05>MAF≥0.005), and aggregate rare variants (MAF<0.005). Meta-analysis of primary results was performed with replication studies containing 12 174 heavy and 11 290 light smokers. Next-generation sequencing with 180X coverage identified 24 nonsynonymous variants and 2 frameshift deletions in CHRNA5, including 9 novel variants in the 2820 subjects. Meta-analysis confirmed the risk effect of the only common variant (rs16969968, European ancestry: OR=1.3, p=3.5×10−11; African ancestry: OR=1.3, p=0.01) and demonstrated that 3 low frequency variants contributed an independent risk (aggregate term, European ancestry: OR=1.3, p=0.005; African ancestry: OR=1.4, p=0.0006). The remaining 22 rare coding variants were associated with increased risk of nicotine dependence in the European American primary sample (OR=12.9, p=0.01) and in the same risk direction in African Americans (OR=1.5, p=0.37). Our results indicate that common, low frequency and rare CHRNA5 coding variants are independently associated with nicotine dependence risk. These newly identified variants likely influence risk for smoking-related diseases such as lung cancer. PMID:26239294

Rare, low frequency and common coding variants in CHRNA5 and their contribution to nicotine dependence in European and African Americans.

PubMed

Olfson, E; Saccone, N L; Johnson, E O; Chen, L-S; Culverhouse, R; Doheny, K; Foltz, S M; Fox, L; Gogarten, S M; Hartz, S; Hetrick, K; Laurie, C C; Marosy, B; Amin, N; Arnett, D; Barr, R G; Bartz, T M; Bertelsen, S; Borecki, I B; Brown, M R; Chasman, D I; van Duijn, C M; Feitosa, M F; Fox, E R; Franceschini, N; Franco, O H; Grove, M L; Guo, X; Hofman, A; Kardia, S L R; Morrison, A C; Musani, S K; Psaty, B M; Rao, D C; Reiner, A P; Rice, K; Ridker, P M; Rose, L M; Schick, U M; Schwander, K; Uitterlinden, A G; Vojinovic, D; Wang, J-C; Ware, E B; Wilson, G; Yao, J; Zhao, W; Breslau, N; Hatsukami, D; Stitzel, J A; Rice, J; Goate, A; Bierut, L J

2016-05-01

The common nonsynonymous variant rs16969968 in the α5 nicotinic receptor subunit gene (CHRNA5) is the strongest genetic risk factor for nicotine dependence in European Americans and contributes to risk in African Americans. To comprehensively examine whether other CHRNA5 coding variation influences nicotine dependence risk, we performed targeted sequencing on 1582 nicotine-dependent cases (Fagerström Test for Nicotine Dependence score⩾4) and 1238 non-dependent controls, with independent replication of common and low frequency variants using 12 studies with exome chip data. Nicotine dependence was examined using logistic regression with individual common variants (minor allele frequency (MAF)⩾0.05), aggregate low frequency variants (0.05>MAF⩾0.005) and aggregate rare variants (MAF<0.005). Meta-analysis of primary results was performed with replication studies containing 12 174 heavy and 11 290 light smokers. Next-generation sequencing with 180 × coverage identified 24 nonsynonymous variants and 2 frameshift deletions in CHRNA5, including 9 novel variants in the 2820 subjects. Meta-analysis confirmed the risk effect of the only common variant (rs16969968, European ancestry: odds ratio (OR)=1.3, P=3.5 × 10(-11); African ancestry: OR=1.3, P=0.01) and demonstrated that three low frequency variants contributed an independent risk (aggregate term, European ancestry: OR=1.3, P=0.005; African ancestry: OR=1.4, P=0.0006). The remaining 22 rare coding variants were associated with increased risk of nicotine dependence in the European American primary sample (OR=12.9, P=0.01) and in the same risk direction in African Americans (OR=1.5, P=0.37). Our results indicate that common, low frequency and rare CHRNA5 coding variants are independently associated with nicotine dependence risk. These newly identified variants likely influence the risk for smoking-related diseases such as lung cancer.
Identification of a novel rhabdovirus in Spodoptera frugiperda cell lines.

PubMed

Ma, Hailun; Galvin, Teresa A; Glasner, Dustin R; Shaheduzzaman, Syed; Khan, Arifa S

2014-06-01

The Sf9 cell line, derived from Spodoptera frugiperda, is used as a cell substrate for biological products, and no viruses have been reported in this cell line after extensive testing. We used degenerate PCR assays and massively parallel sequencing (MPS) to identify a novel RNA virus belonging to the order Mononegavirales in Sf9 cells. Sequence analysis of the assembled virus genome showed the presence of five open reading frames (ORFs) corresponding to the genes for the N, P, M, G, and L proteins in other rhabdoviruses and an unknown ORF of 111 amino acids located between the G- and L-protein genes. BLAST searches indicated that the S. frugiperda rhabdovirus (Sf-rhabdovirus) was related in a limited region of the L-protein gene to Taastrup virus, a newly discovered member of the Mononegavirales from a leafhopper (Hemiptera), and also to plant rhabdoviruses, particularly in the genus Cytorhabdovirus. Phylogenetic analysis of sequences in the L-protein gene indicated that Sf-rhabdovirus is a novel virus that branched with Taastrup virus. Rhabdovirus morphology was confirmed by transmission electron microscopy of filtered supernatant samples from Sf9 cells. Infectivity studies indicated potential transient infection by Sf-rhabdovirus in other insect cell lines, but there was no evidence of entry or virus replication in human cell lines. Sf-rhabdovirus sequences were also found in the Sf21 parental cell line of Sf9 cells but not in other insect cell lines, such as BT1-TN-5B1-4 (Tn5; High Five) cells and Schneider's Drosophila line 2 [D.Mel.(2); SL2] cells, indicating a species-specific infection. The results indicate that conventional methods may be complemented by state-of-the-art technologies with extensive bioinformatics analysis for identification of novel viruses. The Spodoptera frugiperda Sf9 cell line is used as a cell substrate for the development and manufacture of biological products. Extensive testing has not previously identified any viruses in this cell line. This paper reports on the identification and characterization of a novel rhabdovirus in Sf9 cells. This was accomplished through the use of next-generation sequencing platforms, de novo assembly tools, and extensive bioinformatics analysis. Rhabdovirus identification was further confirmed by transmission electron microscopy. Infectivity studies showed the lack of replication of Sf-rhabdovirus in human cell lines. The overall study highlights the use of a combinatorial testing approach including conventional methods and new technologies for evaluation of cell lines for unexpected viruses and use of comprehensive bioinformatics strategies for obtaining confident next-generation sequencing results. Copyright © 2014, American Society for Microbiology. All Rights Reserved.
The lytic origin of herpesvirus papio is highly homologous to Epstein-Barr virus ori-Lyt: evolutionary conservation of transcriptional activation and replication signals.

PubMed Central

Ryon, J J; Fixman, E D; Houchens, C; Zong, J; Lieberman, P M; Chang, Y N; Hayward, G S; Hayward, S D

1993-01-01

Herpesvirus papio (HVP) is a B-lymphotropic baboon virus with an estimated 40% homology to Epstein-Barr virus (EBV). We have cloned and sequenced ori-Lyt of herpesvirus papio and found a striking degree of nucleotide homology (89%) with ori-Lyt of EBV. Transcriptional elements form an integral part of EBV ori-Lyt. The promoter and enhancer domains of EBV ori-Lyt are conserved in herpesvirus papio. The EBV ori-Lyt promoter contains four binding sites for the EBV lytic cycle transactivator Zta, and the enhancer includes one Zta and two Rta response elements. All five of the Zta response elements and one of the Rta motifs are conserved in HVP ori-Lyt, and the HVP DS-L leftward promoter and the enhancer were activated in transient transfection assays by the EBV Zta and Rta transactivators. The EBV ori-Lyt enhancer contains a palindromic sequence, GGTCAGCTGACC, centered on a PvuII restriction site. This sequence, with a single base change, is also present in the HVP ori-Lyt enhancer. DNase I footprinting demonstrated that the PvuII sequence was bound by a protein present in a Raji nuclear extract. Mobility shift and competition assays using oligonucleotide probes identified this sequence as a binding site for the cellular transcription factor MLTF. Mutagenesis of the binding site indicated that MLTF contributes significantly to the constitutive activity of the ori-Lyt enhancer. The high degree of conservation of cis-acting signal sequences in HVP ori-Lyt was further emphasized by the finding that an HVP ori-Lyt-containing plasmid was replicated in Vero cells by a set of cotransfected EBV replication genes. The central domain of EBV ori-Lyt contains two related AT-rich palindromes, one of which is partially duplicated in the HVP sequence. The AT-rich palindromes are functionally important cis-acting motifs. Deletion of these palindromes severely diminished replication of an ori-Lyt target plasmid. Images PMID:8389916
Autonomous replication and addition of telomerelike sequences to DNA microinjected into Paramecium tetraurelia macronuclei.

PubMed Central

Gilley, D; Preer, J R; Aufderheide, K J; Polisky, B

1988-01-01

Paramecium tetraurelia can be transformed by microinjection of cloned serotype A gene sequences into the macronucleus. Transformants are detected by their ability to express serotype A surface antigen from the injected templates. After injection, the DNA is converted from a supercoiled form to a linear form by cleavage at nonrandom sites. The linear form appears to replicate autonomously as a unit-length molecule and is present in transformants at high copy number. The injected DNA is further processed by the addition of paramecium-type telomeric sequences to the termini of the linear DNA. To examine the fate of injected linear DNA molecules, plasmid pSA14SB DNA containing the A gene was cleaved into two linear pieces, a 14-kilobase (kb) piece containing the A gene and flanking sequences and a 2.2-kb piece consisting of the procaryotic vector. In transformants expressing the A gene, we observed that two linear DNA species were present which correspond to the two species injected. Both species had Paramecium telomerelike sequences added to their termini. For the 2.2-kb DNA, we show that the site of addition of the telomerelike sequences is directly at one terminus and within one nucleotide of the other terminus. These results indicate that injected procaryotic DNA is capable of autonomous replication in Paramecium macronuclei and that telomeric addition in the macronucleus does not require specific recognition sequences. Images PMID:3211128
Template Based Design of Anti-Metastatic Drugs from the Active Conformation of Laminin Peptide II

DTIC Science & Technology

2001-01-01

p40 (LBP/p40) gene Maeda, M., Kawasaki, K., Mu, Y., Kamada, H., during sea urchin development. Exp. Cell Res. 221, Tsutsumi, Y., Smith, T. J. & Mayumi...represents the average of six replicates + SEM . minance of putative heparin-binding phage recov- ered from elution with peptide 11. Putative heparin...scrambled sequence peptide, WAQADSTPE, was used as a sequence specificity control. The data shown is the average of six replicate wells ± SEM . Statistics were
Investigation of the Causes of Breast Cancer at the Cellular Level: Isolation of In Vivo Binding Sites of the Human Origin Recognition Complex

DTIC Science & Technology

2002-08-01

We study the process of DNA replication in proliferating human cells. Our efforts are directed to the identification and characterization of proteins...that promote DNA replication (initiators) as well as the DNA sequences recognized by them (replicators) . We have focused in a group of initiator...to be a critical factor for the coordination of DNA replication with the cell division cycle. hOrclp levels are higher between the exit of mitosis and
Identification and characterization of the DNA replication origin recognition complex gene family in the silkworm Bombyx mori.

PubMed

Yang, Hui-Peng; Luo, Su-Juan; Li, Yi-Nü; Zhang, Yao-Zhou; Zhang, Zhi-Fang

2011-10-01

The ORC (origin recognition complex) binds to the DNA replication origin and recruits other replication factors to form the pre-replication complex. The cDNA and genomic sequences of all six subunits of ORC in Bombyx mori (BmORC1-6) were determined by RACE (rapid amplification of cDNA ends) and bioinformatic analysis. The conserved domains were identified in BmOrc1p-6p and the C-terminal of BmOrc6p features a short sequence that may be specific for Lepidoptera. As in other organisms, each of the six BmORC subunits had evolved individually from ancestral genes in early eukaryotes. During embryo development, the six genes were co-regulated, but different ratios of the abundance of mRNAs were observed in 13 tissues of the fifth instar day-6 larvae. Infection by BmNPV (B. mori nucleopolyhedrovirus) initially decreased and then increased the abundance of BmORC. We suggest that some of the BmOrc proteins may have additional functions and that BmOrc proteins participate in the replication of BmNPV.
New insights into replication origin characteristics in metazoans

PubMed Central

Puy, Aurore; Rialle, Stéphanie; Kaplan, Noam; Segal, Eran

2012-01-01

We recently reported the identification and characterization of DNA replication origins (Oris) in metazoan cell lines. Here, we describe additional bioinformatic analyses showing that the previously identified GC-rich sequence elements form origin G-rich repeated elements (OGREs) that are present in 67% to 90% of the DNA replication origins from Drosophila to human cells, respectively. Our analyses also show that initiation of DNA synthesis takes place precisely at 160 bp (Drosophila) and 280 bp (mouse) from the OGRE. We also found that in most CpG islands, an OGRE is positioned in opposite orientation on each of the two DNA strands and detected two sites of initiation of DNA synthesis upstream or downstream of each OGRE. Conversely, Oris not associated with CpG islands have a single initiation site. OGRE density along chromosomes correlated with previously published replication timing data. Ori sequences centered on the OGRE are also predicted to have high intrinsic nucleosome occupancy. Finally, OGREs predict G-quadruplex structures at Oris that might be structural elements controlling the choice or activation of replication origins. PMID:22373526
A DNA Sequence Element That Advances Replication Origin Activation Time in Saccharomyces cerevisiae

PubMed Central

Pohl, Thomas J.; Kolor, Katherine; Fangman, Walton L.; Brewer, Bonita J.; Raghuraman, M. K.

2013-01-01

Eukaryotic origins of DNA replication undergo activation at various times in S-phase, allowing the genome to be duplicated in a temporally staggered fashion. In the budding yeast Saccharomyces cerevisiae, the activation times of individual origins are not intrinsic to those origins but are instead governed by surrounding sequences. Currently, there are two examples of DNA sequences that are known to advance origin activation time, centromeres and forkhead transcription factor binding sites. By combining deletion and linker scanning mutational analysis with two-dimensional gel electrophoresis to measure fork direction in the context of a two-origin plasmid, we have identified and characterized a 19- to 23-bp and a larger 584-bp DNA sequence that are capable of advancing origin activation time. PMID:24022751
Methylation of DNA Ligase 1 by G9a/GLP Recruits UHRF1 to Replicating DNA and Regulates DNA Methylation.

PubMed

Ferry, Laure; Fournier, Alexandra; Tsusaka, Takeshi; Adelmant, Guillaume; Shimazu, Tadahiro; Matano, Shohei; Kirsh, Olivier; Amouroux, Rachel; Dohmae, Naoshi; Suzuki, Takehiro; Filion, Guillaume J; Deng, Wen; de Dieuleveult, Maud; Fritsch, Lauriane; Kudithipudi, Srikanth; Jeltsch, Albert; Leonhardt, Heinrich; Hajkova, Petra; Marto, Jarrod A; Arita, Kyohei; Shinkai, Yoichi; Defossez, Pierre-Antoine

2017-08-17

DNA methylation is an essential epigenetic mark in mammals that has to be re-established after each round of DNA replication. The protein UHRF1 is essential for this process; it has been proposed that the protein targets newly replicated DNA by cooperatively binding hemi-methylated DNA and H3K9me2/3, but this model leaves a number of questions unanswered. Here, we present evidence for a direct recruitment of UHRF1 by the replication machinery via DNA ligase 1 (LIG1). A histone H3K9-like mimic within LIG1 is methylated by G9a and GLP and, compared with H3K9me2/3, more avidly binds UHRF1. Interaction with methylated LIG1 promotes the recruitment of UHRF1 to DNA replication sites and is required for DNA methylation maintenance. These results further elucidate the function of UHRF1, identify a non-histone target of G9a and GLP, and provide an example of a histone mimic that coordinates DNA replication and DNA methylation maintenance. Copyright © 2017 Elsevier Inc. All rights reserved.
Properties of some monkey DNA sequences obtained by a procedure that enriches for DNA replication origins.

PubMed

Zannis-Hadjopoulos, M; Kaufmann, G; Wang, S S; Lechner, R L; Karawya, E; Hesse, J; Martin, R G

1985-07-01

Twelve clones of monkey DNA obtained by a procedure that enriches 10(3)- to 10(4)-fold for nascent sequences activated early in S phase (G. Kaufmann, M. Zannis-Hadjopoulos, and R. G. Martin, Mol. Cell. Biol. 5:721-727, 1985) have been examined. Only 2 of the 12 ors sequences (origin-enriched sequences) are unique (ors1 and ors8). Three contain the highly reiterated Alu family (ors3, ors9, and ors11). One contains the highly reiterated alpha-satellite family (ors12), but none contain the Kpn family. Those remaining contain middle repetitive sequences. Two examples of the same middle repetitive sequence were found (ors2 and ors6). Three of the middle repetitive sequences (the ors2-ors6 pair, ors5, and ors10) are moderately dispersed; one (ors4) is highly dispersed. The last, ors7, has been mapped to the bona fide replication origin of the D loop of mitochondrial DNA. Of the nine ors sequences tested, half possess snapback (intrachain reannealing) properties.
Single Cell Analysis of Human RAD18-Dependent DNA Post-Replication Repair by Alkaline Bromodeoxyuridine Comet Assay

PubMed Central

Mórocz, Mónika; Gali, Himabindu; Raskó, István; Downes, C. Stephen; Haracska, Lajos

2013-01-01

Damage to DNA can block replication progression resulting in gaps in the newly synthesized DNA. Cells utilize a number of post-replication repair (PRR) mechanisms such as the RAD18 controlled translesion synthesis or template switching to overcome the discontinuities formed opposite the DNA lesions and to complete DNA replication. Gaining more insights into the role of PRR genes promotes better understanding of DNA damage tolerance and of how their malfunction can lead to increased genome instability and cancer. However, a simple and efficient method to characterise gene specific PRR deficiencies at a single cell level has not been developed. Here we describe the so named BrdU comet PRR assay to test the contribution of human RAD18 to PRR at a single cell level, by which we kinetically characterized the consequences of the deletion of human RAD18 on the replication of UV-damaged DNA. Moreover, we demonstrate the capability of our method to evaluate PRR at a single cell level in unsynchronized cell population. PMID:23936422
Single Molecule Analysis of Replicated DNA Reveals the Usage of Multiple KSHV Genome Regions for Latent Replication

PubMed Central

Verma, Subhash C.; Lu, Jie; Cai, Qiliang; Kosiyatrakul, Settapong; McDowell, Maria E.; Schildkraut, Carl L.; Robertson, Erle S.

2011-01-01

Kaposi's sarcoma associated herpesvirus (KSHV), an etiologic agent of Kaposi's sarcoma, Body Cavity Based Lymphoma and Multicentric Castleman's Disease, establishes lifelong latency in infected cells. The KSHV genome tethers to the host chromosome with the help of a latency associated nuclear antigen (LANA). Additionally, LANA supports replication of the latent origins within the terminal repeats by recruiting cellular factors. Our previous studies identified and characterized another latent origin, which supported the replication of plasmids ex-vivo without LANA expression in trans. Therefore identification of an additional origin site prompted us to analyze the entire KSHV genome for replication initiation sites using single molecule analysis of replicated DNA (SMARD). Our results showed that replication of DNA can initiate throughout the KSHV genome and the usage of these regions is not conserved in two different KSHV strains investigated. SMARD also showed that the utilization of multiple replication initiation sites occurs across large regions of the genome rather than a specified sequence. The replication origin of the terminal repeats showed only a slight preference for their usage indicating that LANA dependent origin at the terminal repeats (TR) plays only a limited role in genome duplication. Furthermore, we performed chromatin immunoprecipitation for ORC2 and MCM3, which are part of the pre-replication initiation complex to determine the genomic sites where these proteins accumulate, to provide further characterization of potential replication initiation sites on the KSHV genome. The ChIP data confirmed accumulation of these pre-RC proteins at multiple genomic sites in a cell cycle dependent manner. Our data also show that both the frequency and the sites of replication initiation vary within the two KSHV genomes studied here, suggesting that initiation of replication is likely to be affected by the genomic context rather than the DNA sequences. PMID:22072974
Excessive burden of lysosomal storage disorder gene variants in Parkinson's disease.

PubMed

Robak, Laurie A; Jansen, Iris E; van Rooij, Jeroen; Uitterlinden, André G; Kraaij, Robert; Jankovic, Joseph; Heutink, Peter; Shulman, Joshua M

2017-12-01

Mutations in the glucocerebrosidase gene (GBA), which cause Gaucher disease, are also potent risk factors for Parkinson's disease. We examined whether a genetic burden of variants in other lysosomal storage disorder genes is more broadly associated with Parkinson's disease susceptibility. The sequence kernel association test was used to interrogate variant burden among 54 lysosomal storage disorder genes, leveraging whole exome sequencing data from 1156 Parkinson's disease cases and 1679 control subjects. We discovered a significant burden of rare, likely damaging lysosomal storage disorder gene variants in association with Parkinson's disease risk. The association signal was robust to the exclusion of GBA, and consistent results were obtained in two independent replication cohorts, including 436 cases and 169 controls with whole exome sequencing and an additional 6713 cases and 5964 controls with exome-wide genotyping. In secondary analyses designed to highlight the specific genes driving the aggregate signal, we confirmed associations at the GBA and SMPD1 loci and newly implicate CTSD, SLC17A5, and ASAH1 as candidate Parkinson's disease susceptibility genes. In our discovery cohort, the majority of Parkinson's disease cases (56%) have at least one putative damaging variant in a lysosomal storage disorder gene, and 21% carry multiple alleles. Our results highlight several promising new susceptibility loci and reinforce the importance of lysosomal mechanisms in Parkinson's disease pathogenesis. We suggest that multiple genetic hits may act in combination to degrade lysosomal function, enhancing Parkinson's disease susceptibility. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Diversity and distribution of single-stranded DNA phages in the North Atlantic Ocean

PubMed Central

Tucker, Kimberly P; Parsons, Rachel; Symonds, Erin M; Breitbart, Mya

2011-01-01

Knowledge of marine phages is highly biased toward double-stranded DNA (dsDNA) phages; however, recent metagenomic surveys have also identified single-stranded DNA (ssDNA) phages in the oceans. Here, we describe two complete ssDNA phage genomes that were reconstructed from a viral metagenome from 80 m depth at the Bermuda Atlantic Time-series Study (BATS) site in the northwestern Sargasso Sea and examine their spatial and temporal distributions. Both genomes (SARssφ1 and SARssφ2) exhibited similarity to known phages of the Microviridae family in terms of size, GC content, genome organization and protein sequence. PCR amplification of the replication initiation protein (Rep) gene revealed narrow and distinct depth distributions for the newly described ssDNA phages within the upper 200 m of the water column at the BATS site. Comparison of Rep gene sequences obtained from the BATS site over time revealed changes in the diversity of ssDNA phages over monthly time scales, although some nearly identical sequences were recovered from samples collected 4 years apart. Examination of ssDNA phage diversity along transects through the North Atlantic Ocean revealed a positive correlation between genetic distance and geographic distance between sampling sites. Together, the data suggest fundamental differences between the distribution of these ssDNA phages and the distribution of known marine dsDNA phages, possibly because of differences in host range, host distribution, virion stability, or viral evolution mechanisms and rates. Future work needs to elucidate the host ranges for oceanic ssDNA phages and determine their ecological roles in the marine ecosystem. PMID:21124487
Membrane fractions active in poliovirus RNA replication contain VPg precursor polypeptides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takegami, T.; Semler, B.L.; Anderson, C.W.

1983-01-01

The poliovirus specific polypeptide P3-9 is of special interest for studies of viral RNA replication because it contains a hydrophobic region and, separated by only seven amino acids from that region, the amino acid sequence of the genome-linked protein VPg. Membraneous complexes of poliovirus-infected HeLa cells that contain poliovirus RNA replicating proteins have been analyzed for the presence of P3-9 by immunoprecipitation. Incubation of a membrane fraction rich in P3-9 with proteinase leaves the C-terminal 69 amino acids of P3-9 intact, an observation suggesting that this portion is protected by its association with the cellular membrane. These studies have alsomore » revealed two hitherto undescribed viral polypeptides consisting of amino acid sequences of the P2 andf P3 regions of the polyprotein. Sequence analysis by stepwise Edman degradation show that these proteins are 3b/9 (M/sub r/77,000) and X/9 (M/sub r/50,000). 3b/9 and X/9 are membrane bound and are turned over rapidly and may be direct precursors to proteins P2-X and P3-9 of the RNA replication complex. P2-X, a polypeptide void of hydrophobic amino acid sequences but also found associated with membranes, is rapidly degraded when the membraneous complex is treated with trypsin. It is speculated that P2-X is associated with membranes by its affinity to the N-terminus of P3-9.« less
Strand-Specific Analysis of DNA Synthesis and Proteins Association with DNA Replication Forks in Budding Yeast.

PubMed

Yu, Chuanhe; Gan, Haiyun; Zhang, Zhiguo

2018-01-01

DNA replication initiates at DNA replication origins after unwinding of double-strand DNA(dsDNA) by replicative helicase to generate single-stranded DNA (ssDNA) templates for the continuous synthesis of leading-strand and the discontinuous synthesis of lagging-strand. Therefore, methods capable of detecting strand-specific information will likely yield insight into the association of proteins at leading and lagging strand of DNA replication forks and the regulation of leading and lagging strand synthesis during DNA replication. The enrichment and Sequencing of Protein-Associated Nascent DNA (eSPAN), which measure the relative amounts of proteins at nascent leading and lagging strands of DNA replication forks, is a step-wise procedure involving the chromatin immunoprecipitation (ChIP) of a protein of interest followed by the enrichment of protein-associated nascent DNA through BrdU immunoprecipitation. The isolated ssDNA is then subjected to strand-specific sequencing. This method can detect whether a protein is enriched at leading or lagging strand of DNA replication forks. In addition to eSPAN, two other strand-specific methods, (ChIP-ssSeq), which detects potential protein-ssDNA binding and BrdU-IP-ssSeq, which can measure synthesis of both leading and lagging strand, were developed along the way. These methods can provide strand-specific and complementary information about the association of the target protein with DNA replication forks as well as synthesis of leading and lagging strands genome wide. Below, we describe the detailed eSPAN, ChIP-ssSeq, and BrdU-IP-ssSeq protocols.
The Human Cytomegalovirus IE2 and UL112-113 Proteins Accumulate in Viral DNA Replication Compartments That Initiate from the Periphery of Promyelocytic Leukemia Protein-Associated Nuclear Bodies (PODs or ND10)

PubMed Central

Ahn, Jin-Hyun; Jang, Won-Jong; Hayward, Gary S.

1999-01-01

During human cytomegalovirus (HCMV) infection, the periphery of promyelocytic leukemia protein (PML)-associated nuclear bodies (also known as PML oncogenic domains [PODs] or ND10) are sites for both input viral genome deposition and immediate-early (IE) gene transcription. At very early times after infection, the IE1 protein localizes to and subsequently disrupts PODs, whereas the IE2 protein localizes within or adjacent to PODs. This process appears to be required for efficient viral gene expression and DNA replication. We have investigated the initiation of viral DNA replication compartment formation by studying the localization of viral IE proteins, DNA replication proteins, and the PML protein during productive infection. Localization of IE2 adjacent to PODs between 2 and 6 h after infection was confirmed by confocal microscopy of human fibroblasts (HF cells) infected with both wild-type HCMV(Towne) and with an IE1-deletion mutant HCMV(CR208) that fails to disrupt PODs. In HCMV(Towne)-infected HF cells at 24 to 48 h, IE2 also accumulated in newly formed viral DNA replication compartments containing the polymerase processivity factor (UL44), the single-stranded DNA binding protein (SSB; UL57), the UL112-113 accessory protein, and newly incorporated bromodeoxyuridine (BrdU). Double labeling of the HCMV(CR208)-infected HF cells demonstrated that formation of viral DNA replication compartments initiates within granular structures that bud from the periphery of some of the PODs and subsequently coalesce into larger structures that are flanked by PODs. In transient DNA transfection assays, both the N terminus (codons 136 to 290) and the C terminus (codons 379 to 579) of IE2 exon 5, but not the central region between them, were found to be necessary for both the punctate distribution of IE2 and its association with PODs. Like IE2, the UL112-113 accessory replication protein was also distributed in a POD-associated pattern in both DNA-transfected and virus-infected cells beginning at 6 h. Furthermore, when all six replication core machinery proteins (polymerase complex, SSB, and helicase-primase complex) were expressed together in the presence of UL112-113, they also accumulated at POD-associated sites, suggesting that the UL112-113 protein (but not IE2) may play a role in recruitment of viral replication fork proteins into the periphery of PODs. These results show that (i) subsequent to accumulating at the periphery of PODs, IE2 is incorporated together with the core proteins into viral DNA replication compartments that initiate from the periphery of PODs and then grow to fill the space between groups of PODs, and (ii) the UL112-113 protein appears to have a key role in assembling and recruiting the core replication machinery proteins in the initial stages of viral replication compartment formation. PMID:10559364
A Newly Isolated Bacteriophage, PBES 02, Infecting Cronobacter sakazakii.

PubMed

Lee, Hyung Ju; Kim, Wan Il; Kwon, Young Chan; Cha, Kyung Eun; Kim, Minjin; Myung, Heejoon

2016-09-28

A novel bacteriophage, PBES 02, infecting Cronobacter sakazakii was isolated and characterized. It has a spherical head of 90 nm in diameter and a tail of 130 nm in length, and belongs to Myoviridae as observed under a transmission electron microscope. The major virion protein appears to be 38 kilodaltons (kDa) in size. The latent period of PBES 02 is 30 min and the burst size is 250. Infectivity of the phage remained intact after exposure to temperatures ranging from 4°C to 55°C for 1 h. It was also stable after exposure to pHs ranging from 6 to 10 for 1 h. The phage effectively removed contaminating Cronobacter sakazakii from broth infant formula. PBES 02 has a double-stranded DNA genome of 149,732 bases. Its GC ratio is 50.7%. Sequence analysis revealed that PBES 02 has 299 open reading frames (ORFs) and 14 tRNA genes. Thirty-nine ORFs were annotated, including 24 related to replication and regulation functions, 10 related to structural proteins, and 5 related to DNA packaging. The genome of PBES 02 is closely related to that of two other C. sakazakii phages, CR3 and CR8. Comparison of DNA sequences of genes encoding the major capsid protein revealed a wide geographical distribution of related phages over Asia, Europe, and America.
A novel subviral agent associated with a geminivirus: The first report of a DNA satellite

PubMed Central

Dry, Ian B.; Krake, Leslie R.; Rigden, Justin E.; Rezaian, M. Ali

1997-01-01

Numerous plant RNA viruses have associated with them satellite (sat) RNAs that have little or no nucleotide sequence similarity to either the viral or host genomes but are completely dependent on the helper virus for replication. We report here on the discovery of a 682-nt circular DNA satellite associated with tomato leaf curl geminivirus (TLCV) infection in northern Australia. This is the first demonstration that satellite molecules are not limited to RNA viral systems. The DNA satellite (TLCV sat-DNA) is strictly dependent for replication on the helper virus replication-associated protein and is encapsidated by TLCV coat protein. It has no significant open reading frames, and it shows no significant sequence similarity to the 2766-nt helper-virus genome except for two short motifs present in separate putative stem–loop structures: TAATATTAC, which is universally conserved in all geminiviruses, and AATCGGTGTC, which is identical to a putative replication-associated protein binding motif in TLCV. Replication of TLCV sat-DNA is also supported by other taxonomically distinct geminiviruses, including tomato yellow leaf curl virus, African cassava mosaic virus, and beet curly top virus. Therefore, this unique DNA satellite does not appear to strictly conform with the requirements that dictate the specificity of interaction of geminiviral replication-associated proteins with their cognate origins as predicted by the current model of geminivirus replication. PMID:9192696

DNA Replication Origins and Fork Progression at Mammalian Telomeres

PubMed Central

Higa, Mitsunori; Fujita, Masatoshi; Yoshida, Kazumasa

2017-01-01

Telomeres are essential chromosomal regions that prevent critical shortening of linear chromosomes and genomic instability in eukaryotic cells. The bulk of telomeric DNA is replicated by semi-conservative DNA replication in the same way as the rest of the genome. However, recent findings revealed that replication of telomeric repeats is a potential cause of chromosomal instability, because DNA replication through telomeres is challenged by the repetitive telomeric sequences and specific structures that hamper the replication fork. In this review, we summarize current understanding of the mechanisms by which telomeres are faithfully and safely replicated in mammalian cells. Various telomere-associated proteins ensure efficient telomere replication at different steps, such as licensing of replication origins, passage of replication forks, proper fork restart after replication stress, and dissolution of post-replicative structures. In particular, shelterin proteins have central roles in the control of telomere replication. Through physical interactions, accessory proteins are recruited to maintain telomere integrity during DNA replication. Dormant replication origins and/or homology-directed repair may rescue inappropriate fork stalling or collapse that can cause defects in telomere structure and functions. PMID:28350373
Thermodynamic Basis for the Emergence of Genomes during Prebiotic Evolution

PubMed Central

Woo, Hyung-June; Vijaya Satya, Ravi; Reifman, Jaques

2012-01-01

The RNA world hypothesis views modern organisms as descendants of RNA molecules. The earliest RNA molecules must have been random sequences, from which the first genomes that coded for polymerase ribozymes emerged. The quasispecies theory by Eigen predicts the existence of an error threshold limiting genomic stability during such transitions, but does not address the spontaneity of changes. Following a recent theoretical approach, we applied the quasispecies theory combined with kinetic/thermodynamic descriptions of RNA replication to analyze the collective behavior of RNA replicators based on known experimental kinetics data. We find that, with increasing fidelity (relative rate of base-extension for Watson-Crick versus mismatched base pairs), replications without enzymes, with ribozymes, and with protein-based polymerases are above, near, and below a critical point, respectively. The prebiotic evolution therefore must have crossed this critical region. Over large regions of the phase diagram, fitness increases with increasing fidelity, biasing random drifts in sequence space toward ‘crystallization.’ This region encloses the experimental nonenzymatic fidelity value, favoring evolutions toward polymerase sequences with ever higher fidelity, despite error rates above the error catastrophe threshold. Our work shows that experimentally characterized kinetics and thermodynamics of RNA replication allow us to determine the physicochemical conditions required for the spontaneous crystallization of biological information. Our findings also suggest that among many potential oligomers capable of templated replication, RNAs may have evolved to form prebiotic genomes due to the value of their nonenzymatic fidelity. PMID:22693440
Mutations that alter a repeated ACCA element located at the 5' end of the Potato virus X genome affect RNA accumulation.

PubMed

Park, Mi-Ri; Kwon, Sun-Jung; Choi, Hong-Soo; Hemenway, Cynthia L; Kim, Kook-Hyung

2008-08-15

The repeated ACCA or AC-rich sequence and structural (SL1) elements in the 5' non-translated region (NTR) of the Potato virus X (PVX) RNA play vital roles in the PVX life cycle by controlling translation, RNA replication, movement, and assembly. It has already been shown that the repeated ACCA or AC-rich sequence affect both gRNA and sgRNA accumulation, while not affecting minus-strand RNA accumulation, and are also required for host protein binding. The functional significance of the repeated ACCA sequence elements in the 5' NTR region was investigated by analyzing the effects of deletion and site-directed mutations on PVX replication in Nicotiana benthamiana plants and NT1 protoplasts. Substitution (ACCA into AAAA or UUUU) mutations introduced in the first (nt 10-13) element in the 5' NTR of the PVX RNA significantly affected viral replication, while mutations introduced in the second (nt 17-20) and third (nt 20-23) elements did not. The fourth (nt 29-32) ACCA element weakly affected virus replication, whereas mutations in the fifth (nt 38-41) significantly reduced virus replication due to the structure disruption of SL1 by AAAA and/or UUUU substitutions. Further characterization of the first ACCA element indicated that duplication of ACCA at nt 10-13 (nt 10-17, ACCAACCA) caused severe symptom development as compared to that of wild type, while deletion of the single element (nt 10-13), DeltaACCA) or tripling of this element caused reduced symptom development. Single- and double-nucleotide substitutions introduced into the first ACCA element revealed the importance of CC located at nt positions 11 and 12. Altogether, these results indicate that the first ACCA element is important for PVX replication.
Identifying Cancer Driver Genes Using Replication-Incompetent Retroviral Vectors

PubMed Central

Bii, Victor M.; Trobridge, Grant D.

2016-01-01

Identifying novel genes that drive tumor metastasis and drug resistance has significant potential to improve patient outcomes. High-throughput sequencing approaches have identified cancer genes, but distinguishing driver genes from passengers remains challenging. Insertional mutagenesis screens using replication-incompetent retroviral vectors have emerged as a powerful tool to identify cancer genes. Unlike replicating retroviruses and transposons, replication-incompetent retroviral vectors lack additional mutagenesis events that can complicate the identification of driver mutations from passenger mutations. They can also be used for almost any human cancer due to the broad tropism of the vectors. Replication-incompetent retroviral vectors have the ability to dysregulate nearby cancer genes via several mechanisms including enhancer-mediated activation of gene promoters. The integrated provirus acts as a unique molecular tag for nearby candidate driver genes which can be rapidly identified using well established methods that utilize next generation sequencing and bioinformatics programs. Recently, retroviral vector screens have been used to efficiently identify candidate driver genes in prostate, breast, liver and pancreatic cancers. Validated driver genes can be potential therapeutic targets and biomarkers. In this review, we describe the emergence of retroviral insertional mutagenesis screens using replication-incompetent retroviral vectors as a novel tool to identify cancer driver genes in different cancer types. PMID:27792127
RNA N6-adenosine methylation (m6A) steers epitranscriptomic control of herpesvirus replication

PubMed Central

Ye, Fengchun

2017-01-01

Latency is a hallmark of all herpesviruses, during which the viral genomes are silenced through DNA methylation and suppressive histone modifications. When latent herpesviruses reactivate to undergo productive lytic replication, the suppressive epigenetic marks are replaced with active ones to allow for transcription of viral genes. Interestingly, by using Kaposi’s sarcoma-associated herpesvirus (KSHV) as a model, we recently demonstrated that the newly transcribed viral RNAs are also subjected to post-transcriptional N6-adenosine methylation (m6A). Blockade of this post-transcriptional event abolishes viral protein expression and halts virion production. We found that m6A modification controls RNA splicing, stability, and protein translation to regulate viral lytic gene expression and replication. Thus, our finding for the first time reveals a critical role of this epitranscriptomic mechanism in the control of herpesviral replication, which shall shed lights on development of novel strategies for the control of herpesviral infection. PMID:29082271
Construction and Cloning of Reporter-Tagged Replicon cDNA for an In Vitro Replication Study of Murine Norovirus-1 (MNV-1).

PubMed

Ahmad, Muhammad Khairi; Tabana, Yasser M; Ahmed, Mowaffaq Adam; Sandai, Doblin Anak; Mohamed, Rafeezul; Ismail, Ida Shazrina; Zulkiflie, Nurulisa; Yunus, Muhammad Amir

2017-12-01

A norovirus maintains its viability, infectivity and virulence by its ability to replicate. However, the biological mechanisms of the process remain to be explored. In this work, the NanoLuc™ Luciferase gene was used to develop a reporter-tagged replicon system to study norovirus replication. The NanoLuc™ Luciferase reporter protein was engineered to be expressed as a fusion protein for MNV-1 minor capsid protein, VP2. The foot-and-mouth disease virus 2A (FMDV2A) sequence was inserted between the 3'end of the reporter gene and the VP2 start sequence to allow co-translational 'cleavage' of fusion proteins during intracellular transcript expression. Amplification of the fusion gene was performed using a series of standard and overlapping polymerase chain reactions. The resulting amplicon was then cloned into three readily available backbones of MNV-1 cDNA clones. Restriction enzyme analysis indicated that the NanoLucTM Luciferase gene was successfully inserted into the parental MNV-1 cDNA clone. The insertion was further confirmed by using DNA sequencing. NanoLuc™ Luciferase-tagged MNV-1 cDNA clones were successfully engineered. Such clones can be exploited to develop robust experimental assays for in vitro assessments of viral RNA replication.
Transmission of MdSGHV among adult house flies, Musca domestica (Diptera: Muscidae), via salivary secretions and excreta.

USDA-ARS?s Scientific Manuscript database

The Musca domestica salivary gland hypertrophy virus (MdSGHV) is a newly characterized, double stranded DNA virus that replicates in the salivary glands of infected adult house flies. Transmission of this non-occluded, enveloped virus within feral populations of M. domestica is believed to be media...
The Dynamics of DNA Sequencing.

ERIC Educational Resources Information Center

Morvillo, Nancy

1997-01-01

Describes a paper-and-pencil activity that helps students understand DNA sequencing and expands student understanding of DNA structure, replication, and gel electrophoresis. Appropriate for advanced biology students who are familiar with the Sanger method. (DDR)
Epstein-Barr virus origin of lytic replication mediates association of replicating episomes with promyelocytic leukaemia protein nuclear bodies and replication compartments.

PubMed

Amon, Wolfgang; White, Robert E; Farrell, Paul J

2006-05-01

Epstein-Barr virus (EBV) establishes a latent persistence from which it can be reactivated to undergo lytic replication. Late lytic-cycle gene expression is linked to lytic DNA replication, as it is sensitive to the same inhibitors that block lytic replication, and it has recently been shown that the viral origin of lytic replication (ori lyt) is required in cis for late-gene expression. During the lytic cycle, the viral genome forms replication compartments, which are usually adjacent to promyelocytic leukaemia protein (PML) nuclear bodies. A tetracycline repressor DNA-binding domain-enhanced green fluorescent protein fusion was used to visualize replicating plasmids carrying a tetracycline operator sequence array. ori lyt mediated the production of plasmid replication compartments that were associated with PML nuclear bodies. Plasmids carrying ori lyt and EBV itself were visualized in the same cells and replicated in similar regions of the nucleus, further supporting the validity of the plasmids for studying late-gene regulation.
A ribonucleotide Origin for Life - Fluctuation and Near-ideal Reactions

NASA Astrophysics Data System (ADS)

Yarus, Michael

2013-02-01

Oligoribonucleotides are potentially capable of Darwinian evolution - they may replicate and can express an independent chemical phenotype, as embodied in modern enzymatic cofactors. Using quantitative chemical kinetics on a sporadically fed ribonucleotide pool, unreliable supplies of unstable activated ribonucleotides A and B at low concentrations recurrently yield a replicating AB polymer with a potential chemical phenotype. Self-complementary replication in the pool occurs during a minority (here ≈ 35 %) of synthetic episodes that exploit coincidental overlaps between 4, 5 or 6 spikes of arbitrarily arriving substrates. Such uniquely productive synthetic episodes, in which near-ideal reaction sequences recur at random, account for most AB oligonucleotide synthesis, and therefore underlie the emergence of net replication under realistic primordial conditions. Because overlapping substrate spikes are unexpectedly frequent, and in addition, complex spike sequences appear disproportionately, a sporadically fed pool can host unexpectedly complex syntheses. Thus, primordial substrate fluctuations are not necessarily a barrier to Darwinism, but instead can facilitate early evolution.
A ribonucleotide Origin for Life--fluctuation and near-ideal reactions.

PubMed

Yarus, Michael

2013-02-01

Oligoribonucleotides are potentially capable of Darwinian evolution - they may replicate and can express an independent chemical phenotype, as embodied in modern enzymatic cofactors. Using quantitative chemical kinetics on a sporadically fed ribonucleotide pool, unreliable supplies of unstable activated ribonucleotides A and B at low concentrations recurrently yield a replicating AB polymer with a potential chemical phenotype. Self-complementary replication in the pool occurs during a minority (here ≈ 35 %) of synthetic episodes that exploit coincidental overlaps between 4, 5 or 6 spikes of arbitrarily arriving substrates. Such uniquely productive synthetic episodes, in which near-ideal reaction sequences recur at random, account for most AB oligonucleotide synthesis, and therefore underlie the emergence of net replication under realistic primordial conditions. Because overlapping substrate spikes are unexpectedly frequent, and in addition, complex spike sequences appear disproportionately, a sporadically fed pool can host unexpectedly complex syntheses. Thus, primordial substrate fluctuations are not necessarily a barrier to Darwinism, but instead can facilitate early evolution.
Active role of a human genomic insert in replication of a yeast artificial chromosome.

PubMed

van Brabant, A J; Fangman, W L; Brewer, B J

1999-06-01

Yeast artificial chromosomes (YACs) are a common tool for cloning eukaryotic DNA. The manner by which large pieces of foreign DNA are assimilated by yeast cells into a functional chromosome is poorly understood, as is the reason why some of them are stably maintained and some are not. We examined the replication of a stable YAC containing a 240-kb insert of DNA from the human T-cell receptor beta locus. The human insert contains multiple sites that serve as origins of replication. The activity of these origins appears to require the yeast ARS consensus sequence and, as with yeast origins, additional flanking sequences. In addition, the origins in the human insert exhibit a spacing, a range of activation efficiencies, and a variation in times of activation during S phase similar to those found for normal yeast chromosomes. We propose that an appropriate combination of replication origin density, activation times, and initiation efficiencies is necessary for the successful maintenance of YAC inserts.
The Limits of Template-Directed Synthesis with Nucleoside-5'-Phosphoro(2-Methyl) Imidazolides

NASA Technical Reports Server (NTRS)

Hill, Aubrey R., Jr.; Orgel, Leslie E.; Wu, Taifeng

1993-01-01

In earlier work we have shown that C-rich templates containing isolated A, T or G residues and short oligo(G) sequences can be copied effectively using nucleoside-5'-phosphoro(2-methyl)imidazolides as substrates. We now show that isolated A or T residues within an oligo(G) sequence are a complete block to copying and that an isolated C residue is copied inefficiently. Replication is possible only if there are two complementary oligonucleotides each of which acts as a template to facilitate the synthesis of the other. We emphasize the severity of the problems that need to be overcome to make possible non-enzymatic replication in homogeneous aqueous solution. We conclude that an efficient catalyst was involved in the origin of polynucleotide replication.
Translational genomics for plant breeding with the genome sequence explosion.

PubMed

Kang, Yang Jae; Lee, Taeyoung; Lee, Jayern; Shim, Sangrea; Jeong, Haneul; Satyawan, Dani; Kim, Moon Young; Lee, Suk-Ha

2016-04-01

The use of next-generation sequencers and advanced genotyping technologies has propelled the field of plant genomics in model crops and plants and enhanced the discovery of hidden bridges between genotypes and phenotypes. The newly generated reference sequences of unstudied minor plants can be annotated by the knowledge of model plants via translational genomics approaches. Here, we reviewed the strategies of translational genomics and suggested perspectives on the current databases of genomic resources and the database structures of translated information on the new genome. As a draft picture of phenotypic annotation, translational genomics on newly sequenced plants will provide valuable assistance for breeders and researchers who are interested in genetic studies. © 2015 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.
Mutations in the newly identified RAX regulatory sequence are not a frequent cause of micro/anophthalmia.

PubMed

Chassaing, Nicolas; Vigouroux, Adeline; Calvas, Patrick

2009-06-01

Microphthalmia and anophthalmia are at the severe end of the spectrum of abnormalities in ocular development. A few genes (SOX2, OTX2, RAX, and CHX10) have been implicated in isolated micro/anophthalmia, but causative mutations of these genes explain less than a quarter of these developmental defects. A specifically conserved SOX2/OTX2-mediated RAX expression regulatory sequence has recently been identified. We postulated that mutations in this sequence could lead to micro/anophthalmia, and thus we performed molecular screening of this regulatory element in patients suffering from micro/anophthalmia. Fifty-one patients suffering from nonsyndromic microphthalmia (n = 40) or anophthalmia (n = 11) were included in this study after negative molecular screening for SOX2, OTX2, RAX, and CHX10 mutations. Mutation screening of the RAX regulatory sequence was performed by direct sequencing for these patients. No mutations were identified in the highly conserved RAX regulatory sequence in any of the 51 patients. Mutations in the newly identified RAX regulatory sequence do not represent a frequent cause of nonsyndromic micro/anophthalmia.
Deletion of the S component inverted repeat sequence c' and the nonessential genes U(S)1 through U(S)5 from the herpes simplex virus type 1 genome substantially impairs productive viral infection in cell culture and pathogenesis in the rat central nervous system.

PubMed

Rasty, S; Poliani, P L; Fink, D J; Glorioso, J C

1997-08-01

A distinctive feature of the genetic make-up of herpes simplex virus type 1 (HSV-1), a human neurotropic virus, is that approximately half of the 81 known viral genes are not absolutely required for productive infection in Vero cells, and most can be individually deleted without substantially impairing viral replication in cell culture. If large blocks of contiguous viral genes could be replaced with foreign DNA sequences, it would be possible to engineer highly attenuated recombinant HSV-1 gene transfer vectors capable of carrying large cellular genes or multiple genes having related functions. We report the isolation and characterization of an HSV-1 mutant, designated d311, containing a 12 kb deletion of viral DNA located between the L-S Junction a sequence and the U(S)6 gene, spanning the S component inverted repeat sequence c' and the nonessential genes U(S)1 through U(S)5. Replication of d311 was totally inhibited in rat B103 and mouse Neuro-2A neuroblastoma cell lines, and was reduced by over three orders of magnitude in human SK-N-SH neuroblastoma cells compared to wild-type (wt) HSV-1 KOS. This suggested that the deleted genes, while nonessential for replication in Vero cells, play an important role in HSV replication in neuronal cells, particularly those of rodent origin. Unlike wt KOS which replicated locally and spread to other regions of brain following stereotactic inoculation into rat hippocampus, d311 was unable to replicate and spread within the brain, and did not cause any apparent local neuronal cell damage. These results demonstrate that d311 is highly attenuated for the rat central nervous system. d311 and other mutants of HSV containing major deletions of the nonessential genes within U(S) have the potential to serve as useful tools for gene transfer applications to brain.
The complete CDS of the prion protein (PRNP) gene of African lion (Panthera leo).

PubMed

Maj, Andrzej; Spellman, Garth M; Sarver, Shane K

2008-04-01

We provide the complete PRNP CDS sequence for the African lion, which is different from the previously published sequence and more similar to other carnivore sequences. The newly obtained prion protein sequence differs from the domestic cat sequence at three amino acid positions and contains only four octapeptide repeats. We recommend that this sequence be used as the reference sequence for future studies of the PRNP gene for this species.
RPA binds histone H3-H4 and functions in DNA replication-coupled nucleosome assembly.

PubMed

Liu, Shaofeng; Xu, Zhiyun; Leng, He; Zheng, Pu; Yang, Jiayi; Chen, Kaifu; Feng, Jianxun; Li, Qing

2017-01-27

DNA replication-coupled nucleosome assembly is essential to maintain genome integrity and retain epigenetic information. Multiple involved histone chaperones have been identified, but how nucleosome assembly is coupled to DNA replication remains elusive. Here we show that replication protein A (RPA), an essential replisome component that binds single-stranded DNA, has a role in replication-coupled nucleosome assembly. RPA directly binds free H3-H4. Assays using a synthetic sequence that mimics freshly unwound single-stranded DNA at replication fork showed that RPA promotes DNA-(H3-H4) complex formation immediately adjacent to double-stranded DNA. Further, an RPA mutant defective in H3-H4 binding exhibited attenuated nucleosome assembly on nascent chromatin. Thus, we propose that RPA functions as a platform for targeting histone deposition to replication fork, through which RPA couples nucleosome assembly with ongoing DNA replication. Copyright © 2017, American Association for the Advancement of Science.
RNA interference inhibits herpes simplex virus type 1 isolated from saliva samples and mucocutaneous lesions.

PubMed

Silva, Amanda Perse da; Lopes, Juliana Freitas; Paula, Vanessa Salete de

2014-01-01

The aim of this study was to evaluate the use of RNA interference to inhibit herpes simplex virus type-1 replication in vitro. For herpes simplex virus type-1 gene silencing, three different small interfering RNAs (siRNAs) targeting the herpes simplex virus type-1 UL39 gene (sequence si-UL 39-1, si-UL 39-2, and si-UL 39-3) were used, which encode the large subunit of ribonucleotide reductase, an essential enzyme for DNA synthesis. Herpes simplex virus type-1 was isolated from saliva samples and mucocutaneous lesions from infected patients. All mucocutaneous lesions' samples were positive for herpes simplex virus type-1 by real-time PCR and by virus isolation; all herpes simplex virus type-1 from saliva samples were positive by real-time PCR and 50% were positive by virus isolation. The levels of herpes simplex virus type-1 DNA remaining after siRNA treatment were assessed by real-time PCR, whose results demonstrated that the effect of siRNAs on gene expression depends on siRNA concentration. The three siRNA sequences used were able to inhibit viral replication, assessed by real-time PCR and plaque assays and among them, the sequence si-UL 39-1 was the most effective. This sequence inhibited 99% of herpes simplex virus type-1 replication. The results demonstrate that silencing herpes simplex virus type-1 UL39 expression by siRNAs effectively inhibits herpes simplex virus type-1 replication, suggesting that siRNA based antiviral strategy may be a potential therapeutic alternative. Copyright © 2014. Published by Elsevier Editora Ltda.
A distinct first replication cycle of DNA introduced in mammalian cells

PubMed Central

Chandok, Gurangad S.; Kapoor, Kalvin K.; Brick, Rachel M.; Sidorova, Julia M.; Krasilnikova, Maria M.

2011-01-01

Many mutation events in microsatellite DNA sequences were traced to the first embryonic divisions. It was not known what makes the first replication cycles of embryonic DNA different from subsequent replication cycles. Here we demonstrate that an unusual replication mode is involved in the first cycle of replication of DNA introduced in mammalian cells. This alternative replication starts at random positions, and occurs before the chromatin is fully assembled. It is detected in various cell lines and primary cells. The presence of single-stranded regions increases the efficiency of this alternative replication mode. The alternative replication cannot progress through the A/T-rich FRA16B fragile site, while the regular replication mode is not affected by it. A/T-rich microsatellites are associated with the majority of chromosomal breakpoints in cancer. We suggest that the alternative replication mode may be initiated at the regions with immature chromatin structure in embryonic and cancer cells resulting in increased genomic instability. This work demonstrates, for the first time, differences in the replication progression during the first and subsequent replication cycles in mammalian cells. PMID:21062817

Replication of a chronic hepatitis B virus genotype F1b construct.

PubMed

Hernández, Sergio; Jiménez, Gustavo; Alarcón, Valentina; Prieto, Cristian; Muñoz, Francisca; Riquelme, Constanza; Venegas, Mauricio; Brahm, Javier; Loyola, Alejandra; Villanueva, Rodrigo A

2016-03-01

Genotype F is one of the less-studied genotypes of human hepatitis B virus, although it is widely distributed in regions of Central and South American. Our previous studies have shown that HBV genotype F is prevalent in Chile, and phylogenetic analysis of its full-length sequence amplified from the sera of chronically infected patients identified it as HBV subgenotype F1b. We have previously reported the full-length sequence of a HBV molecular clone obtained from a patient chronically infected with genotype F1b. In this report, we established a system to study HBV replication based on hepatoma cell lines transfected with full-length monomers of the HBV genome. Culture supernatants were analyzed after transfection and found to contain both HBsAg and HBeAg viral antigens. Consistently, fractionated cell extracts revealed the presence of viral replication, with both cytoplasmic and nuclear DNA intermediates. Analysis of HBV-transfected cells by indirect immunofluorescence or immunoelectron microscopy revealed the expression of viral antigens and cytoplasmic viral particles, respectively. To test the functionality of the ongoing viral replication further at the level of chromatinized cccDNA, transfected cells were treated with a histone deacetylase inhibitor, and this resulted in increased viral replication. This correlated with changes posttranslational modifications of histones at viral promoters. Thus, the development of this viral replication system for HBV genotype F will facilitate studies on the regulation of viral replication and the identification of new antiviral drugs.
Project UPSTART. Final Report, October 1, 1983-September 30, 1984.

ERIC Educational Resources Information Center

Frain, Joan

Project UPSTART, during this fourth year of outreach, offered assistance in replicating its developed Sequenced Neuro-Sensorimotor Program (SNSP) for severely multihandicapped infants, pre-schoolers, young adults and their families. Future replication sites were identified. Programs received outreach assistance in the areas of staff training,…
A novel begomovirus isolated from sida contains putative cis- and trans-acting replication specificity determinants that have evolved independently in several geographical lineages.

PubMed

Mauricio-Castillo, J A; Torres-Herrera, S I; Cárdenas-Conejo, Y; Pastor-Palacios, G; Méndez-Lozano, J; Argüello-Astorga, G R

2014-09-01

A novel begomovirus isolated from a Sida rhombifolia plant collected in Sinaloa, Mexico, was characterized. The genomic components of sida mosaic Sinaloa virus (SiMSinV) shared highest sequence identity with DNA-A and DNA-B components of chino del tomate virus (CdTV), suggesting a vertical evolutionary relationship between these viruses. However, recombination analysis indicated that a short segment of SiMSinV DNA-A encompassing the plus-strand replication origin and the 5´-proximal 43 codons of the Rep gene was derived from tomato mottle Taino virus (ToMoTV). Accordingly, the putative cis- and trans-acting replication specificity determinants of SiMSinV were identical to those of ToMoTV but differed from those of CdTV. Modeling of the SiMSinV and CdTV Rep proteins revealed significant differences in the region comprising the small β1/β5 sheet element, where five putative DNA-binding specificity determinants (SPDs) of Rep (i.e., amino acid residues 5, 8, 10, 69 and 71) were previously identified. Computer-assisted searches of public databases led to identification of 33 begomoviruses from three continents encoding proteins with SPDs identical to those of the Rep encoded by SiMSinV. Sequence analysis of the replication origins demonstrated that all 33 begomoviruses harbor potential Rep-binding sites identical to those of SiMSinV. These data support the hypothesis that the Rep β1/β5 sheet region determines specificity of this protein for DNA replication origin sequences.
Signal amplification of padlock probes by rolling circle replication.

PubMed Central

Banér, J; Nilsson, M; Mendel-Hartvig, M; Landegren, U

1998-01-01

Circularizing oligonucleotide probes (padlock probes) have the potential to detect sets of gene sequences with high specificity and excellent selectivity for sequence variants, but sensitivity of detection has been limiting. By using a rolling circle replication (RCR) mechanism, circularized but not unreacted probes can yield a powerful signal amplification. We demonstrate here that in order for the reaction to proceed efficiently, the probes must be released from the topological link that forms with target molecules upon hybridization and ligation. If the target strand has a nearby free 3' end, then the probe-target hybrids can be displaced by the polymerase used for replication. The displaced probe can then slip off the targetstrand and a rolling circle amplification is initiated. Alternatively, the target sequence itself can prime an RCR after its non-base paired 3' end has been removed by exonucleolytic activity. We found the Phi29 DNA polymerase to be superior to the Klenow fragment in displacing the target DNA strand, and it maintained the polymerization reaction for at least 12 h, yielding an extension product that represents several thousand-fold the length of the padlock probe. PMID:9801302
Distinct Mechanisms of Nuclease-Directed DNA-Structure-Induced Genetic Instability in Cancer Genomes.

PubMed

Zhao, Junhua; Wang, Guliang; Del Mundo, Imee M; McKinney, Jennifer A; Lu, Xiuli; Bacolla, Albino; Boulware, Stephen B; Zhang, Changsheng; Zhang, Haihua; Ren, Pengyu; Freudenreich, Catherine H; Vasquez, Karen M

2018-01-30

Sequences with the capacity to adopt alternative DNA structures have been implicated in cancer etiology; however, the mechanisms are unclear. For example, H-DNA-forming sequences within oncogenes have been shown to stimulate genetic instability in mammals. Here, we report that H-DNA-forming sequences are enriched at translocation breakpoints in human cancer genomes, further implicating them in cancer etiology. H-DNA-induced mutations were suppressed in human cells deficient in the nucleotide excision repair nucleases, ERCC1-XPF and XPG, but were stimulated in cells deficient in FEN1, a replication-related endonuclease. Further, we found that these nucleases cleaved H-DNA conformations, and the interactions of modeled H-DNA with ERCC1-XPF, XPG, and FEN1 proteins were explored at the sub-molecular level. The results suggest mechanisms of genetic instability triggered by H-DNA through distinct structure-specific, cleavage-based replication-independent and replication-dependent pathways, providing critical evidence for a role of the DNA structure itself in the etiology of cancer and other human diseases. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.
Exploring the roles of DNA methylation in the metal-reducing bacterium Shewanella oneidensis MR-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bendall, Matthew L.; Luong, Khai; Wetmore, Kelly M.

2013-08-30

We performed whole genome analyses of DNA methylation in Shewanella 17 oneidensis MR-1 to examine its possible role in regulating gene expression and 18 other cellular processes. Single-Molecule Real Time (SMRT) sequencing 19 revealed extensive methylation of adenine (N6mA) throughout the 20 genome. These methylated bases were located in five sequence motifs, 21 including three novel targets for Type I restriction/modification enzymes. The 22 sequence motifs targeted by putative methyltranferases were determined via 23 SMRT sequencing of gene knockout mutants. In addition, we found S. 24 oneidensis MR-1 cultures grown under various culture conditions displayed 25 different DNA methylation patterns.more » However, the small number of differentially 26 methylated sites could not be directly linked to the much larger number of 27 differentially expressed genes in these conditions, suggesting DNA methylation is 28 not a major regulator of gene expression in S. oneidensis MR-1. The enrichment 29 of methylated GATC motifs in the origin of replication indicate DNA methylation 30 may regulate genome replication in a manner similar to that seen in Escherichia 31 coli. Furthermore, comparative analyses suggest that many 32 Gammaproteobacteria, including all members of the Shewanellaceae family, may 33 also utilize DNA methylation to regulate genome replication.« less
Electron microscopic visualization of sites of nascent DNA synthesis by streptavidin-gold binding to biotinylated nucleotides incorporated in vivo

PubMed Central

1988-01-01

Biotinylated nucleotides (bio-11-dCTP, bio-11-dUTP, and bio-7-dATP) were microinjected into unfertilized and fertilized Xenopus laevis eggs. The amounts introduced were comparable to in vivo deoxy- nucleoside triphosphate pools. At various times after microinjection, DNA was extracted from eggs or embryos and subjected to electrophoresis on agarose gels. Newly synthesized biotinylated DNA was analyzed by Southern transfer and visualized using either the BluGENE or Detek-hrp streptavidin-based nucleic acid detection systems. Quantitation of the amount of biotinylated DNA observed at various times showed that the microinjected biotinylated nucleotides were efficiently incorporated in vivo, both into replicating endogenous chromosomal DNA and into replicating microinjected exogenous plasmid DNA. At least one biotinylated nucleotide could be incorporated in vivo for every eight nucleotides of DNA synthesized. Control experiments also showed that heavily biotinylated DNA was not subjected to detectable DNA repair during early embryogenesis (for at least 5 h after activation of the eggs). The incorporated biotinylated nucleotides were visualized by electron microscopy by using streptavidin-colloidal gold or streptavidin-ferritin conjugates to bind specifically to the biotin groups projecting from the newly replicated DNA. The incorporated biotinylated nucleotides were thus made visible as electron-dense spots on the underlying DNA molecules. Biotinylated nucleotides separated by 20-50 bases could be resolved. We conclude that nascent DNA synthesized in vivo in Xenopus laevis eggs can be visualized efficiently and specifically using the techniques described. PMID:3392102
Replication of newly identified type 2 diabetes susceptible loci in Northwest Indian population.

PubMed

Sharma, Varun; Sharma, Indu; Sethi, Itty; Mahajan, Ankit; Singh, Gurvinder; Angural, Arshia; Bhanwer, A J S; Dhar, Manoj K; Singh, Vinod; Rai, Ekta; Sharma, Swarkar

2017-04-01

To replicate the association of newly identified variants of TMEM163 (transmembrane protein 163) and COBLL1 (cordon-bleu protein-like 1) with type 2 diabetes (T2D) in Northwest Indian population. We performed a replication study of variants rs998451 and rs6723108 of gene TMEM163 and rs7607980 of gene COBLL1. The variations were genotyped using Taqman allele discrimination assay in 1209 Northwest Indians (651 T2D cases and 558 controls). The association of each SNP with the disease was evaluated using logistic regression. All the three SNPs examined in this study did not show any significant association with T2D. For rs998451 and rs6723108 of TMEM163 the observed odds ratios were 0.71 with a 95% CI of 0.28-1.84 (p=0.484) and 1.80 with a 95% CI of 0.74-4.40 (p=0.196), respectively. For rs7607980 the estimated odds ratio was 1.01 with 95% CI of 0.70-1.44 (p=0.946). We conclude that lack of association could be because of population structure of Indian Population that is conglomeration of various ethnic groups. For a conclusive association study of T2D in India, it is critical that such studies are carried out among endogamous ethnic groups rather than conventional practice of pooling samples based on Geographical/regional or linguist affiliations like Asian Indian, North or South Indian etc. Copyright © 2017 Elsevier B.V. All rights reserved.
Plum Pox Virus 6K1 Protein Is Required for Viral Replication and Targets the Viral Replication Complex at the Early Stage of Infection

PubMed Central

Cui, Hongguang

2016-01-01

ABSTRACT The potyviral RNA genome encodes two polyproteins that are proteolytically processed by three viral protease domains into 11 mature proteins. Extensive molecular studies have identified functions for the majority of the viral proteins. For example, 6K2, one of the two smallest potyviral proteins, is an integral membrane protein and induces the endoplasmic reticulum (ER)-originated replication vesicles that target the chloroplast for robust viral replication. However, the functional role of 6K1, the other smallest protein, remains uncharacterized. In this study, we developed a series of recombinant full-length viral cDNA clones derived from a Canadian Plum pox virus (PPV) isolate. We found that deletion of any of the short motifs of 6K1 (each of which ranged from 5 to 13 amino acids), most of the 6K1 sequence (but with the conserved sequence of the cleavage sites being retained), or all of the 6K1 sequence in the PPV infectious clone abolished viral replication. The trans expression of 6K1 or the cis expression of a dislocated 6K1 failed to rescue the loss-of-replication phenotype, suggesting the temporal and spatial requirement of 6K1 for viral replication. Disruption of the N- or C-terminal cleavage site of 6K1, which prevented the release of 6K1 from the polyprotein, either partially or completely inhibited viral replication, suggesting the functional importance of the mature 6K1. We further found that green fluorescent protein-tagged 6K1 formed punctate inclusions at the viral early infection stage and colocalized with chloroplast-bound viral replicase elements 6K2 and NIb. Taken together, our results suggest that 6K1 is required for viral replication and is an important viral element of the viral replication complex at the early infection stage. IMPORTANCE Potyviruses account for more than 30% of known plant viruses and consist of many agriculturally important viruses. The genomes of potyviruses encode two polyproteins that are proteolytically processed into 11 mature proteins, with the majority of them having been at least partially functionally characterized. However, the functional role of a small protein named 6K1 remains obscure. In this study, we showed that deletion of 6K1 or a short motif/region of 6K1 in the full-length cDNA clones of plum pox virus abolishes viral replication and that mutation of the N- or C-terminal cleavage sites of 6K1 to prevent its release from the polyprotein greatly attenuates or completely inhibits viral replication, suggesting its important role in potyviral infection. We report that 6K1 forms punctate structures and targets the replication vesicles in PPV-infected plant leaf cells at the early infection stage. Our data reveal that 6K1 is an important viral protein of the potyviral replication complex. PMID:26962227
In silico ribozyme evolution in a metabolically coupled RNA population.

PubMed

Könnyű, Balázs; Szilágyi, András; Czárán, Tamás

2015-05-27

The RNA World hypothesis offers a plausible bridge from no-life to life on prebiotic Earth, by assuming that RNA, the only known molecule type capable of playing genetic and catalytic roles at the same time, could have been the first evolvable entity on the evolutionary path to the first living cell. We have developed the Metabolically Coupled Replicator System (MCRS), a spatially explicit simulation modelling approach to prebiotic RNA-World evolution on mineral surfaces, in which we incorporate the most important experimental facts and theoretical considerations to comply with recent knowledge on RNA and prebiotic evolution. In this paper the MCRS model framework has been extended in order to investigate the dynamical and evolutionary consequences of adding an important physico-chemical detail, namely explicit replicator structure - nucleotide sequence and 2D folding calculated from thermodynamical criteria - and their possible mutational changes, to the assumptions of a previously less detailed toy model. For each mutable nucleotide sequence the corresponding 2D folded structure with minimum free energy is calculated, which in turn is used to determine the fitness components (degradation rate, replicability and metabolic enzyme activity) of the replicator. We show that the community of such replicators providing the monomer supply for their own replication by evolving metabolic enzyme activities features an improved propensity for stable coexistence and structural adaptation. These evolutionary advantages are due to the emergent uniformity of metabolic replicator fitnesses imposed on the community by local group selection and attained through replicator trait convergence, i.e., the tendency of replicator lengths, ribozyme activities and population sizes to become similar between the coevolving replicator species that are otherwise both structurally and functionally different. In the most general terms it is the surprisingly high extra viability of the metabolic replicator system that the present model adds to the MCRS concept of the origin of life. Surface-bound, metabolically coupled RNA replicators tend to evolve different, enzymatically active sites within thermodynamically stable secondary structures, and the system as a whole evolves towards the robust coexistence of a complete set of such ribozymes driving the metabolism producing monomers for their own replication.
Prevalence effects in newly trained airport checkpoint screeners: trained observers miss rare targets, too.

PubMed

Wolfe, Jeremy M; Brunelli, David N; Rubinstein, Joshua; Horowitz, Todd S

2013-12-02

Many socially important search tasks are characterized by low target prevalence, meaning that targets are rarely encountered. For example, transportation security officers (TSOs) at airport checkpoints encounter very few actual threats in carry-on bags. In laboratory-based visual search experiments, low prevalence reduces the probability of detecting targets (Wolfe, Horowitz, & Kenner, 2005). In the lab, this "prevalence effect" is caused by changes in decision and response criteria (Wolfe & Van Wert, 2010) and can be mitigated by presenting a burst of high-prevalence search with feedback (Wolfe et al., 2007). The goal of this study was to see if these effects could be replicated in the field with TSOs. A total of 125 newly trained TSOs participated in one of two experiments as part of their final evaluation following training. They searched for threats in simulated bags across five blocks. The first three blocks were low prevalence (target prevalence ≤ .05) with no feedback; the fourth block was high prevalence (.50) with full feedback; and the final block was, again, low prevalence. We found that newly trained TSOs were better at detecting targets at high compared to low prevalence, replicating the prevalence effect. Furthermore, performance was better (and response criterion was more "liberal") in the low-prevalence block that took place after the high-prevalence block than in the initial three low-prevalence blocks, suggesting that a burst of high-prevalence trials may help alleviate the prevalence effect in the field.
Prevalence effects in newly trained airport checkpoint screeners: Trained observers miss rare targets, too

PubMed Central

Wolfe, Jeremy M.; Brunelli, David N.; Rubinstein, Joshua; Horowitz, Todd S.

2013-01-01

Many socially important search tasks are characterized by low target prevalence, meaning that targets are rarely encountered. For example, transportation security officers (TSOs) at airport checkpoints encounter very few actual threats in carry-on bags. In laboratory-based visual search experiments, low prevalence reduces the probability of detecting targets (Wolfe, Horowitz, & Kenner, 2005). In the lab, this “prevalence effect” is caused by changes in decision and response criteria (Wolfe & Van Wert, 2010) and can be mitigated by presenting a burst of high-prevalence search with feedback (Wolfe et al., 2007). The goal of this study was to see if these effects could be replicated in the field with TSOs. A total of 125 newly trained TSOs participated in one of two experiments as part of their final evaluation following training. They searched for threats in simulated bags across five blocks. The first three blocks were low prevalence (target prevalence ≤ .05) with no feedback; the fourth block was high prevalence (.50) with full feedback; and the final block was, again, low prevalence. We found that newly trained TSOs were better at detecting targets at high compared to low prevalence, replicating the prevalence effect. Furthermore, performance was better (and response criterion was more “liberal”) in the low-prevalence block that took place after the high-prevalence block than in the initial three low-prevalence blocks, suggesting that a burst of high-prevalence trials may help alleviate the prevalence effect in the field. PMID:24297778
Flavivirus Replication Complex Assembly Revealed by DNAJC14 Functional Mapping

PubMed Central

Yi, Zhigang; Yuan, Zhenghong; Rice, Charles M.

2012-01-01

DNAJC14 is an Hsp40 family member that broadly modulates flavivirus replication. The mechanism by which DNAJC14 stoichiometrically participates in flavivirus replication complex (RC) formation is unknown; both reduced and elevated levels result in replication inhibition. Using yellow fever virus (YFV), we demonstrate that DNAJC14 redistributes and clusters with YFV nonstructural proteins via a transmembrane domain and a newly identified membrane-binding domain (MBD), which both mediate targeting to detergent-resistant membranes. Furthermore, the RC and DNAJC14 reside as part of a protein interaction network that remains after 1% Triton solubilization. Mutagenesis studies demonstrate that entry into this protein interaction network requires the DNAJC14 C-terminal self-interaction domain. Fusion of the DNAJC14 MBD and self-interaction domain with another Hsp40 family protein is sufficient to confer YFV-inhibitory activity. Our findings support a novel model of DNAJC14 action that includes specific membrane targeting of both DNAJC14 and YFV replication proteins, the formation of protein interactions, and a microdomain-specific chaperone event leading to RC formation. This process alters the properties of the RC membrane and results in the formation of a protein scaffold that maintains the RC. PMID:22915803
Initiation at closely spaced replication origins in a yeast chromosome.

PubMed

Brewer, B J; Fangman, W L

1993-12-10

Replication of eukaryotic chromosomes involves initiation at origins spaced an average of 50 to 100 kilobase pairs. In yeast, potential origins can be recognized as autonomous replication sequences (ARSs) that allow maintenance of plasmids. However, there are more ARS elements than active chromosomal origins. The possibility was examined that close spacing of ARSs can lead to inactive origins. Two ARSs located 6.5 kilobase pairs apart can indeed interfere with each other. Replication is initiated from one or the other ARS with equal probability, but rarely (< 5%) from both ARSs on the same DNA molecule.
Concurrent micro-RNA mediated silencing of tick-borne flavivirus replication in tick vector and in the brain of vertebrate host.

PubMed

Tsetsarkin, Konstantin A; Liu, Guangping; Kenney, Heather; Hermance, Meghan; Thangamani, Saravanan; Pletnev, Alexander G

2016-09-13

Tick-borne viruses include medically important zoonotic pathogens that can cause life-threatening diseases. Unlike mosquito-borne viruses, whose impact can be restrained via mosquito population control programs, for tick-borne viruses only vaccination remains the reliable means of disease prevention. For live vaccine viruses a concern exists, that spillovers from viremic vaccinees could result in introduction of genetically modified viruses into sustainable tick-vertebrate host transmission cycle in nature. To restrict tick-borne flavivirus (Langat virus, LGTV) vector tropism, we inserted target sequences for tick-specific microRNAs (mir-1, mir-275 and mir-279) individually or in combination into several distant regions of LGTV genome. This caused selective attenuation of viral replication in tick-derived cells. LGTV expressing combinations of target sequences for tick- and vertebrate CNS-specific miRNAs were developed. The resulting viruses replicated efficiently and remained stable in simian Vero cells, which do not express these miRNAs, however were severely restricted to replicate in tick-derived cells. In addition, simultaneous dual miRNA targeting led to silencing of virus replication in live Ixodes ricinus ticks and abolished virus neurotropism in highly permissive newborn mice. The concurrent restriction of adverse replication events in vertebrate and invertebrate hosts will, therefore, ensure the environmental safety of live tick-borne virus vaccine candidates.
Characterization of the Campylobacter jejuni cryptic plasmid pTIW94 recovered from wild birds in the southeastern United States.

PubMed

Hiett, Kelli L; Rothrock, Michael J; Seal, Bruce S

2013-09-01

The complete nucleotide sequence was determined for a cryptic plasmid, pTIW94, recovered from several Campylobacter jejuni isolates from wild birds in the southeastern United States. pTIW94 is a circular molecule of 3860 nucleotides, with a G+C content (31.0%) similar to that of many Campylobacter spp. genomes. A typical origin of replication, with iteron sequences, was identified upstream of DNA sequences that demonstrated similarity to replication initiation proteins. A total of five open reading frames (ORFs) were identified; two of the five ORFs demonstrated significant similarity to plasmid pCC2228-2 found within Campylobacter coli. These two ORFs were similar to essential replication proteins RepA (100%; 26/26 aa identity) and RepB (95%; 327/346 aa identity). A third identified ORF demonstrated significant similarity (99%; 421/424 aa identity) to the MOB protein from C. coli 67-8, originally recovered from swine. The other two identified ORFs were either similar to hypothetical proteins from other Campylobacter spp., or exhibited no significant similarity to any DNA or protein sequence in the GenBank database. Promoter regions (-35 and -10 signal sites), ribosomal binding sites upstream of ORFs, and stem-loop structures were also identified within the plasmid. These results demonstrate that pTIW94 represents a previously un-reported small cryptic plasmid with unique sequences as well as highly similar sequences to other small plasmids found within Campylobacter spp., and that this cryptic plasmid is present among Campylobacter spp. recovered from different genera of wild birds. Copyright © 2013. Published by Elsevier Inc.
Randomization and In Vivo Selection Reveal a GGRG Motif Essential for Packaging Human Immunodeficiency Virus Type 2 RNA ▿ †

PubMed Central

Baig, Tayyba T.; Lanchy, Jean-Marc; Lodmell, J. Stephen

2009-01-01

The packaging signal (ψ) of human immunodeficiency virus type 2 (HIV-2) is present in the 5′ noncoding region of RNA and contains a 10-nucleotide palindrome (pal; 5′-392-GGAGUGCUCC) located upstream of the dimerization signal stem-loop 1 (SL1). pal has been shown to be functionally important in vitro and in vivo. We previously showed that the 3′ side of pal (GCUCC-3′) is involved in base-pairing interactions with a sequence downstream of SL1 to make an extended SL1, which is important for replication in vivo and the regulation of dimerization in vitro. However, the role of the 5′ side of pal (5′-GGAGU) was less clear. Here, we characterized this role using an in vivo SELEX approach. We produced a population of HIV-2 DNA genomes with random sequences within the 5′ side of pal and transfected these into COS-7 cells. Viruses from COS-7 cells were used to infect C8166 permissive cells. After several weeks of serial passage in C8166 cells, surviving viruses were sequenced. On the 5′ side of pal there was a striking convergence toward a GGRGN consensus sequence. Individual clones with consensus and nonconsensus sequences were tested in infectivity and packaging assays. Analysis of individuals that diverged from the consensus sequence showed normal viral RNA and protein synthesis but had replication defects and impaired RNA packaging. These findings clearly indicate that the GGRG motif is essential for viral replication and genomic RNA packaging. PMID:18971263
Bridging from Replication to Translation with a Thermal, Autonomous Replicator Made from Transfer RNA

NASA Astrophysics Data System (ADS)

Braun, Dieter; Möller, Friederike M.; Krammer, Hubert

2013-03-01

Central to the understanding of living systems is the interplay between DNA/RNA and proteins. Known as Eigen paradox, proteins require genetic information while proteins are needed for the replication of genes. RNA world scenarios focus on a base by base replication disconnected from translation. Here we used strategies from DNA machines to demonstrate a tight connection between a basic replication mechanism and translation. A pool of hairpin molecules replicate a two-letter code. The replication is thermally driven: the energy and negative entropy to drive replication is initially stored in metastable hairpins by kinetic cooling. Both are released by a highly specific and exponential replication reaction that is solely implemented by base hybridization. The duplication time is 30s. The reaction is monitored by fluorescence and described by a detailed kinetic model. The RNA hairpins usetransfer RNA sequences and the replication is driven by the simple disequilibrium setting of a thermal gradient The experiments propose a physical rather than a chemical scenario for the autonomous replication of protein encoding information. Supported by the NanoSystems Initiative Munich and ERC.
Important role of N108 residue in binding of bovine foamy virus transactivator Tas to viral promoters.

PubMed

Bing, Tiejun; Zhang, Suzhen; Liu, Xiaojuan; Liang, Zhibin; Shao, Peng; Zhang, Song; Qiao, Wentao; Tan, Juan

2016-06-30

Bovine foamy virus (BFV) encodes the transactivator BTas, which enhances viral gene transcription by binding to the long terminal repeat promoter and the internal promoter. In this study, we investigated the different replication capacities of two similar BFV full-length DNA clones, pBS-BFV-Y and pBS-BFV-B. Here, functional analysis of several chimeric clones revealed a major role for the C-terminal region of the viral genome in causing this difference. Furthermore, BTas-B, which is located in this C-terminal region, exhibited a 20-fold higher transactivation activity than BTas-Y. Sequence alignment showed that these two sequences differ only at amino acid 108, with BTas-B containing N108 and BTas-Y containing D108 at this position. Results of mutagenesis studies demonstrated that residue N108 is important for BTas binding to viral promoters. In addition, the N108D mutation in pBS-BFV-B reduced the viral replication capacity by about 1.5-fold. Our results suggest that residue N108 is important for BTas binding to BFV promoters and has a major role in BFV replication. These findings not only advances our understanding of the transactivation mechanism of BTas, but they also highlight the importance of certain sequence polymorphisms in modulating the replication capacity of isolated BFV clones.
Construction and Cloning of Reporter-Tagged Replicon cDNA for an In Vitro Replication Study of Murine Norovirus-1 (MNV-1)

PubMed Central

Ahmad, Muhammad Khairi; Tabana, Yasser M; Ahmed, Mowaffaq Adam; Sandai, Doblin Anak; Mohamed, Rafeezul; Ismail, Ida Shazrina; Zulkiflie, Nurulisa; Yunus, Muhammad Amir

2017-01-01

Background A norovirus maintains its viability, infectivity and virulence by its ability to replicate. However, the biological mechanisms of the process remain to be explored. In this work, the NanoLuc™ Luciferase gene was used to develop a reporter-tagged replicon system to study norovirus replication. Methods The NanoLuc™ Luciferase reporter protein was engineered to be expressed as a fusion protein for MNV-1 minor capsid protein, VP2. The foot-and-mouth disease virus 2A (FMDV2A) sequence was inserted between the 3′end of the reporter gene and the VP2 start sequence to allow co-translational ‘cleavage’ of fusion proteins during intracellular transcript expression. Amplification of the fusion gene was performed using a series of standard and overlapping polymerase chain reactions. The resulting amplicon was then cloned into three readily available backbones of MNV-1 cDNA clones. Results Restriction enzyme analysis indicated that the NanoLucTM Luciferase gene was successfully inserted into the parental MNV-1 cDNA clone. The insertion was further confirmed by using DNA sequencing. Conclusion NanoLuc™ Luciferase-tagged MNV-1 cDNA clones were successfully engineered. Such clones can be exploited to develop robust experimental assays for in vitro assessments of viral RNA replication. PMID:29379384

Overlapping local and long-range RNA-RNA interactions modulate dengue virus genome cyclization and replication.

PubMed

de Borba, Luana; Villordo, Sergio M; Iglesias, Nestor G; Filomatori, Claudia V; Gebhard, Leopoldo G; Gamarnik, Andrea V

2015-03-01

The dengue virus genome is a dynamic molecule that adopts different conformations in the infected cell. Here, using RNA folding predictions, chemical probing analysis, RNA binding assays, and functional studies, we identified new cis-acting elements present in the capsid coding sequence that facilitate cyclization of the viral RNA by hybridization with a sequence involved in a local dumbbell structure at the viral 3' untranslated region (UTR). The identified interaction differentially enhances viral replication in mosquito and mammalian cells. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
Inherited Mitochondrial Diseases of DNA Replication

PubMed Central

Copeland, William C.

2007-01-01

Mitochondrial genetic diseases can result from defects in mitochondrial DNA (mtDNA) in the form of deletions, point mutations, or depletion, which ultimately cause loss of oxidative phosphorylation. These mutations may be spontaneous, maternally inherited, or a result of inherited nuclear defects in genes that maintain mtDNA. This review focuses on our current understanding of nuclear gene mutations that produce mtDNA alterations and cause mitochondrial depletion syndrome (MDS), progressive external ophthalmoplegia (PEO), ataxia-neuropathy, or mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). To date, all of these etiologic nuclear genes fall into one of two categories: genes whose products function directly at the mtDNA replication fork, such as POLG, POLG2, and TWINKLE, or genes whose products supply the mitochondria with deoxynucleotide triphosphate pools needed for DNA replication, such as TK2, DGUOK, TP, SUCLA2, ANT1, and possibly the newly identified MPV17. PMID:17892433
Hepatitis A Virus Genome Organization and Replication Strategy.

PubMed

McKnight, Kevin L; Lemon, Stanley M

2018-04-02

Hepatitis A virus (HAV) is a positive-strand RNA virus classified in the genus Hepatovirus of the family Picornaviridae It is an ancient virus with a long evolutionary history and multiple features of its capsid structure, genome organization, and replication cycle that distinguish it from other mammalian picornaviruses. HAV proteins are produced by cap-independent translation of a single, long open reading frame under direction of an inefficient, upstream internal ribosome entry site (IRES). Genome replication occurs slowly and is noncytopathic, with transcription likely primed by a uridylated protein primer as in other picornaviruses. Newly produced quasi-enveloped virions (eHAV) are released from cells in a nonlytic fashion in a unique process mediated by interactions of capsid proteins with components of the host cell endosomal sorting complexes required for transport (ESCRT) system. Copyright © 2018 Cold Spring Harbor Laboratory Press; all rights reserved.
ER-mitochondria contacts couple mtDNA synthesis with mitochondrial division in human cells.

PubMed

Lewis, Samantha C; Uchiyama, Lauren F; Nunnari, Jodi

2016-07-15

Mitochondrial DNA (mtDNA) encodes RNAs and proteins critical for cell function. In human cells, hundreds to thousands of mtDNA copies are replicated asynchronously, packaged into protein-DNA nucleoids, and distributed within a dynamic mitochondrial network. The mechanisms that govern how nucleoids are chosen for replication and distribution are not understood. Mitochondrial distribution depends on division, which occurs at endoplasmic reticulum (ER)-mitochondria contact sites. These sites were spatially linked to a subset of nucleoids selectively marked by mtDNA polymerase and engaged in mtDNA synthesis--events that occurred upstream of mitochondrial constriction and division machine assembly. Our data suggest that ER tubules proximal to nucleoids are necessary but not sufficient for mtDNA synthesis. Thus, ER-mitochondria contacts coordinate licensing of mtDNA synthesis with division to distribute newly replicated nucleoids to daughter mitochondria. Copyright © 2016, American Association for the Advancement of Science.
Modes of Human T Cell Leukemia Virus Type 1 Transmission, Replication and Persistence

PubMed Central

Carpentier, Alexandre; Barez, Pierre-Yves; Hamaidia, Malik; Gazon, Hélène; de Brogniez, Alix; Perike, Srikanth; Gillet, Nicolas; Willems, Luc

2015-01-01

Human T-cell leukemia virus type 1 (HTLV-1) is a retrovirus that causes cancer (Adult T cell Leukemia, ATL) and a spectrum of inflammatory diseases (mainly HTLV-associated myelopathy—tropical spastic paraparesis, HAM/TSP). Since virions are particularly unstable, HTLV-1 transmission primarily occurs by transfer of a cell carrying an integrated provirus. After transcription, the viral genomic RNA undergoes reverse transcription and integration into the chromosomal DNA of a cell from the newly infected host. The virus then replicates by either one of two modes: (i) an infectious cycle by virus budding and infection of new targets and (ii) mitotic division of cells harboring an integrated provirus. HTLV-1 replication initiates a series of mechanisms in the host including antiviral immunity and checkpoint control of cell proliferation. HTLV-1 has elaborated strategies to counteract these defense mechanisms allowing continuous persistence in humans. PMID:26198240
The Minimal Replicator of Epstein-Barr Virus oriP

PubMed Central

Yates, John L.; Camiolo, Sarah M.; Bashaw, Jacqueline M.

2000-01-01

oriP is a 1.7-kb region of the Epstein-Barr virus (EBV) chromosome that supports the replication and stable maintenance of plasmids in human cells. oriP contains two essential components, called the DS and the FR, both of which contain multiple binding sites for the EBV-encoded protein, EBNA-1. The DS appears to function as the replicator of oriP, while the FR acts in conjunction with EBNA-1 to prevent the loss of plasmids from proliferating cells. Because of EBNA-1's role in stabilizing plasmids through the FR, it has not been entirely clear to what extent EBNA-1 might be required for replication from oriP per se, and a recent study has questioned whether EBNA-1 has any direct role in replication. In the present study we found that plasmids carrying oriP required EBNA-1 to replicate efficiently even when assayed only 2 days after plasmids were introduced into the cell lines 143B and 293. Significantly, using 293 cells it was demonstrated that the plasmid-retention function of EBNA-1 and the FR did not contribute significantly to the accumulation of replicated plasmids, and the DS supported efficient EBNA-1-dependent replication in the absence of the FR. The DS contains two pairs of closely spaced EBNA-1 binding sites, and a previous study had shown that both sites within either pair are required for activity. However, it was unclear from previous work what additional sequences within the DS might be required. We found that each “half” of the DS, including a pair of closely spaced EBNA-1 binding sites, had significant replicator activity when the other half had been deleted. The only significant DNA sequences that the two halves of the DS share in common, other than EBNA-1 binding sites, is a 9-bp sequence that is present twice in the “left half” and once in the “right half.” These nonamer repeats, while not essential for activity, contributed significantly to the activity of each half of the DS. Two thymines occur at unique positions within EBNA-1 binding sites 1 and 4 at the DS and become sensitive to oxidation by permanganate when EBNA-1 binds, but mutation of each to the consensus base, adenine, actually improved the activity of each half of the DS slightly. In conclusion, the DS of oriP is an EBNA-1-dependent replicator, and its minimal active core appears to be simply two properly spaced EBNA-1 binding sites. PMID:10775587
Isolation and molecular cloning of a fast-growing strain of human hepatitis A virus from its double-stranded replicative form.

PubMed Central

Venuti, A; Di Russo, C; del Grosso, N; Patti, A M; Ruggeri, F; De Stasio, P R; Martiniello, M G; Pagnotti, P; Degener, A M; Midulla, M

1985-01-01

A fast-growing strain of human hepatitis A virus was selected and characterized. The virus has the unusual property of developing a strong cytopathic effect in tissue culture in 7 to 10 days. Sequences of the viral genome were cloned into recombinant plasmids with the double-stranded replicative form as a template for the reverse transcription of cDNA. Restriction analysis and direct sequencing indicate that this strain is different from that described by Ticehurst et al. (Proc. Natl. Acad. Sci. USA 80:5885-5889, 1983) in the region that presumptively codes for the major capsid protein VP1, but both isolates have conserved large areas of homology in the untranslated 5'-terminal sequences of the genome. Images PMID:2997478
Genetic characterization of human herpesvirus type 1: Full-length genome sequence of strain obtained from an encephalitis case from India.

PubMed

Bondre, Vijay P; Sankararaman, Vasudha; Andhare, Vijaysinh; Tupekar, Manisha; Sapkal, Gajanan N

2016-11-01

Human herpes simplex virus 1 (HSV-1) is the most common cause of sporadic encephalitis in humans that contributes to >10 per cent of the encephalitis cases occurring worldwide. Availability of limited full genome sequences from a small number of isolates resulted in poor understanding of host and viral factors responsible for variable clinical outcome. In this study genetic relationship, extent and source of recombination using full-length genome sequence derived from a newly isolated HSV-1 isolate was studied in comparison with those sampled from patients with varied clinical outcome. Full genome sequence of HSV-1 isolated from cerebrospinal fluid (CSF) of a patient with acute encephalitis syndrome (AES) by inoculation in baby hamster kidney-21 (BHK-21) cells was determined using next-generation sequencing (NGS) technology. Phylogenetic analysis of the newly generated sequence in comparison with 33 additional full-length genomes defined genetic relationship with worldwide distributed strains. The bootscan and similarity plot analysis defined recombination crossovers and similarities between newly isolated Indian HSV-1 with six Asian and a total of 34 worldwide isolated strains. Mapping of 376,332 reads amplified from HSV-1 DNA by NGS generated full-length genome of 151,024 bp from newly isolated Indian HSV-1. Phylogenetic analysis classified worldwide distributed strains into three major evolutionary lineages correlating to their geographic distribution. Lineage 1 containing strains were isolated from America and Europe; lineage 2 contained all the strains from Asian countries along with the North American KOS and RE strains whereas the South African isolates were distributed into two groups under lineage 3. Recombination analysis confirmed events of recombination in Indian HSV-1 genome resulting from mixing of different strains evolved in Asian countries. Our results showed that the full-length genome sequence generated from an Indian HSV-1 isolate shared close genetic relationship with the American KOS and Chinese CR38 strains which belonged to the Asian genetic lineage. Recombination analysis of Indian isolate demonstrated multiple recombination crossover points throughout the genome. This full-length genome sequence amplified from the Indian isolate would be helpful to study HSV evolution, genetic basis of differential pathogenesis, host-virus interactions and viral factors contributing towards differential clinical outcome in human infections.
Genetic characterization of human herpesvirus type 1: Full-length genome sequence of strain obtained from an encephalitis case from India

PubMed Central

Bondre, Vijay P.; Sankararaman, Vasudha; Andhare, Vijaysinh; Tupekar, Manisha; Sapkal, Gajanan N.

2016-01-01

Background & objectives: Human herpes simplex virus 1 (HSV-1) is the most common cause of sporadic encephalitis in humans that contributes to >10 per cent of the encephalitis cases occurring worldwide. Availability of limited full genome sequences from a small number of isolates resulted in poor understanding of host and viral factors responsible for variable clinical outcome. In this study genetic relationship, extent and source of recombination using full-length genome sequence derived from a newly isolated HSV-1 isolate was studied in comparison with those sampled from patients with varied clinical outcome. Methods: Full genome sequence of HSV-1 isolated from cerebrospinal fluid (CSF) of a patient with acute encephalitis syndrome (AES) by inoculation in baby hamster kidney-21 (BHK-21) cells was determined using next-generation sequencing (NGS) technology. Phylogenetic analysis of the newly generated sequence in comparison with 33 additional full-length genomes defined genetic relationship with worldwide distributed strains. The bootscan and similarity plot analysis defined recombination crossovers and similarities between newly isolated Indian HSV-1 with six Asian and a total of 34 worldwide isolated strains. Results: Mapping of 376,332 reads amplified from HSV-1 DNA by NGS generated full-length genome of 151,024 bp from newly isolated Indian HSV-1. Phylogenetic analysis classified worldwide distributed strains into three major evolutionary lineages correlating to their geographic distribution. Lineage 1 containing strains were isolated from America and Europe; lineage 2 contained all the strains from Asian countries along with the North American KOS and RE strains whereas the South African isolates were distributed into two groups under lineage 3. Recombination analysis confirmed events of recombination in Indian HSV-1 genome resulting from mixing of different strains evolved in Asian countries. Interpretation & conclusions: Our results showed that the full-length genome sequence generated from an Indian HSV-1 isolate shared close genetic relationship with the American KOS and Chinese CR38 strains which belonged to the Asian genetic lineage. Recombination analysis of Indian isolate demonstrated multiple recombination crossover points throughout the genome. This full-length genome sequence amplified from the Indian isolate would be helpful to study HSV evolution, genetic basis of differential pathogenesis, host-virus interactions and viral factors contributing towards differential clinical outcome in human infections. PMID:28361829
Generation of Recombinant Polioviruses Harboring RNA Affinity Tags in the 5′ and 3′ Noncoding Regions of Genomic RNAs

PubMed Central

Flather, Dylan; Cathcart, Andrea L.; Cruz, Casey; Baggs, Eric; Ngo, Tuan; Gershon, Paul D.; Semler, Bert L.

2016-01-01

Despite being intensely studied for more than 50 years, a complete understanding of the enterovirus replication cycle remains elusive. Specifically, only a handful of cellular proteins have been shown to be involved in the RNA replication cycle of these viruses. In an effort to isolate and identify additional cellular proteins that function in enteroviral RNA replication, we have generated multiple recombinant polioviruses containing RNA affinity tags within the 3′ or 5′ noncoding region of the genome. These recombinant viruses retained RNA affinity sequences within the genome while remaining viable and infectious over multiple passages in cell culture. Further characterization of these viruses demonstrated that viral protein production and growth kinetics were unchanged or only slightly altered relative to wild type poliovirus. However, attempts to isolate these genetically-tagged viral genomes from infected cells have been hindered by high levels of co-purification of nonspecific proteins and the limited matrix-binding efficiency of RNA affinity sequences. Regardless, these recombinant viruses represent a step toward more thorough characterization of enterovirus ribonucleoprotein complexes involved in RNA replication. PMID:26861382
Non-coding stem-bulge RNAs are required for cell proliferation and embryonic development in C. elegans

PubMed Central

Kowalski, Madzia P.; Baylis, Howard A.; Krude, Torsten

2015-01-01

ABSTRACT Stem bulge RNAs (sbRNAs) are a family of small non-coding stem-loop RNAs present in Caenorhabditis elegans and other nematodes, the function of which is unknown. Here, we report the first functional characterisation of nematode sbRNAs. We demonstrate that sbRNAs from a range of nematode species are able to reconstitute the initiation of chromosomal DNA replication in the presence of replication proteins in vitro, and that conserved nucleotide sequence motifs are essential for this function. By functionally inactivating sbRNAs with antisense morpholino oligonucleotides, we show that sbRNAs are required for S phase progression, early embryonic development and the viability of C. elegans in vivo. Thus, we demonstrate a new and essential role for sbRNAs during the early development of C. elegans. sbRNAs show limited nucleotide sequence similarity to vertebrate Y RNAs, which are also essential for the initiation of DNA replication. Our results therefore establish that the essential function of small non-coding stem-loop RNAs during DNA replication extends beyond vertebrates. PMID:25908866
Inter-Fork Strand Annealing causes genomic deletions during the termination of DNA replication.

PubMed

Morrow, Carl A; Nguyen, Michael O; Fower, Andrew; Wong, Io Nam; Osman, Fekret; Bryer, Claire; Whitby, Matthew C

2017-06-06

Problems that arise during DNA replication can drive genomic alterations that are instrumental in the development of cancers and many human genetic disorders. Replication fork barriers are a commonly encountered problem, which can cause fork collapse and act as hotspots for replication termination. Collapsed forks can be rescued by homologous recombination, which restarts replication. However, replication restart is relatively slow and, therefore, replication termination may frequently occur by an active fork converging on a collapsed fork. We find that this type of non-canonical fork convergence in fission yeast is prone to trigger deletions between repetitive DNA sequences via a mechanism we call Inter-Fork Strand Annealing (IFSA) that depends on the recombination proteins Rad52, Exo1 and Mus81, and is countered by the FANCM-related DNA helicase Fml1. Based on our findings, we propose that IFSA is a potential threat to genomic stability in eukaryotes.
Loss of maintenance DNA methylation results in abnormal DNA origin firing during DNA replication.

PubMed

Haruta, Mayumi; Shimada, Midori; Nishiyama, Atsuya; Johmura, Yoshikazu; Le Tallec, Benoît; Debatisse, Michelle; Nakanishi, Makoto

2016-01-22

The mammalian maintenance methyltransferase DNMT1 [DNA (cytosine-5-)-methyltransferase 1] mediates the inheritance of the DNA methylation pattern during replication. Previous studies have shown that depletion of DNMT1 causes a severe growth defect and apoptosis in differentiated cells. However, the detailed mechanisms behind this phenomenon remain poorly understood. Here we show that conditional ablation of Dnmt1 in murine embryonic fibroblasts (MEFs) resulted in an aberrant DNA replication program showing an accumulation of late-S phase replication and causing severely defective growth. Furthermore, we found that the catalytic activity and replication focus targeting sequence of DNMT1 are required for a proper DNA replication program. Taken together, our findings suggest that the maintenance of DNA methylation by DNMT1 plays a critical role in proper regulation of DNA replication in mammalian cells. Copyright © 2015 Elsevier Inc. All rights reserved.
The hunt for origins of DNA replication in multicellular eukaryotes

PubMed Central

Urban, John M.; Foulk, Michael S.; Casella, Cinzia

2015-01-01

Origins of DNA replication (ORIs) occur at defined regions in the genome. Although DNA sequence defines the position of ORIs in budding yeast, the factors for ORI specification remain elusive in metazoa. Several methods have been used recently to map ORIs in metazoan genomes with the hope that features for ORI specification might emerge. These methods are reviewed here with analysis of their advantages and shortcomings. The various factors that may influence ORI selection for initiation of DNA replication are discussed. PMID:25926981
A Novel Model System to Examine Agents Used in Breast Cancer Therapy.

DTIC Science & Technology

1995-07-01

We have recently characterized a multiprotein DNA replication complex (MRC) that was purified from NODA NIB 468 human breast cancer cells by a series...proliferating cell nuclear antigen (PCNA), RE-C RP-A and DNA topoisomerase I. Based upon its requirements for DNA replication activity and its...SV4O) origin sequences, the MRC executes all of the steps required for the in vitro, bidirectional replication of the SV4O genome. Several of the DNA
Productive Homologous and Non-homologous Recombination of Hepatitis C Virus in Cell Culture

PubMed Central

Li, Yi-Ping; Mikkelsen, Lotte S.; Gottwein, Judith M.; Bukh, Jens

2013-01-01

Genetic recombination is an important mechanism for increasing diversity of RNA viruses, and constitutes a viral escape mechanism to host immune responses and to treatment with antiviral compounds. Although rare, epidemiologically important hepatitis C virus (HCV) recombinants have been reported. In addition, recombination is an important regulatory mechanism of cytopathogenicity for the related pestiviruses. Here we describe recombination of HCV RNA in cell culture leading to production of infectious virus. Initially, hepatoma cells were co-transfected with a replicating JFH1ΔE1E2 genome (genotype 2a) lacking functional envelope genes and strain J6 (2a), which has functional envelope genes but does not replicate in culture. After an initial decrease in the number of HCV positive cells, infection spread after 13–36 days. Sequencing of recovered viruses revealed non-homologous recombinants with J6 sequence from the 5′ end to the NS2–NS3 region followed by JFH1 sequence from Core to the 3′ end. These recombinants carried duplicated sequence of up to 2400 nucleotides. HCV replication was not required for recombination, as recombinants were observed in most experiments even when two replication incompetent genomes were co-transfected. Reverse genetic studies verified the viability of representative recombinants. After serial passage, subsequent recombination events reducing or eliminating the duplicated region were observed for some but not all recombinants. Furthermore, we found that inter-genotypic recombination could occur, but at a lower frequency than intra-genotypic recombination. Productive recombination of attenuated HCV genomes depended on expression of all HCV proteins and tolerated duplicated sequence. In general, no strong site specificity was observed. Non-homologous recombination was observed in most cases, while few homologous events were identified. A better understanding of HCV recombination could help identification of natural recombinants and thereby lead to improved therapy. Our findings suggest mechanisms for occurrence of recombinants observed in patients. PMID:23555245
Mec1/ATR, the Program Manager of Nucleic Acids Inc.

PubMed

Feng, Wenyi

2016-12-28

Eukaryotic cells are equipped with surveillance mechanisms called checkpoints to ensure proper execution of cell cycle events. Among these are the checkpoints that detect DNA damage or replication perturbations and coordinate cellular activities to maintain genome stability. At the forefront of damage sensing is an evolutionarily conserved molecule, known respectively in budding yeast and humans as Mec1 (Mitosis entry checkpoint 1) and ATR (Ataxia telangiectasia and Rad3-related protein). Through phosphorylation, Mec1/ATR activates downstream components of a signaling cascade to maintain nucleotide pool balance, protect replication fork integrity, regulate activation of origins of replication, coordinate DNA repair, and implement cell cycle delay. This list of functions continues to expand as studies have revealed that Mec1/ATR modularly interacts with various protein molecules in response to different cellular cues. Among these newly assigned functions is the regulation of RNA metabolism during checkpoint activation and the coordination of replication-transcription conflicts. In this review, I will highlight some of these new functions of Mec1/ATR with a focus on the yeast model organism.
Complete replication of hepatitis B virus and hepatitis C virus in a newly developed hepatoma cell line.

PubMed

Yang, Darong; Zuo, Chaohui; Wang, Xiaohong; Meng, Xianghe; Xue, Binbin; Liu, Nianli; Yu, Rong; Qin, Yuwen; Gao, Yimin; Wang, Qiuping; Hu, Jun; Wang, Ling; Zhou, Zebin; Liu, Bing; Tan, Deming; Guan, Yang; Zhu, Haizhen

2014-04-01

The absence of a robust cell culture system for hepatitis B virus (HBV) and hepatitis C virus (HCV) infection has limited the analysis of the virus lifecycle and drug discovery. We have established a hepatoma cell line, HLCZ01, the first cell line, to the authors' knowledge, supporting the entire lifecycle of both HBV and HCV. HBV surface antigen (HBsAg)-positive particles can be observed in the supernatant and the lumen of the endoplasmic reticulum of the cells via electron microscopy. Interestingly, HBV and HCV clinical isolates propagate in HLCZ01 cells. Both viruses replicate in the cells without evidence of overt interference. HBV and HCV entry are blocked by antibodies against HBsAg and human CD81, respectively, and the replication of HBV and HCV is inhibited by antivirals. HLCZ01 cells mount an innate immune response to virus infection. The cell line provides a powerful tool for exploring the mechanisms of virus entry and replication and the interaction between host and virus, facilitating the development of novel antiviral agents and vaccines.
microRNA-122 target sites in the hepatitis C virus RNA NS5B coding region and 3' untranslated region: function in replication and influence of RNA secondary structure.

PubMed

Gerresheim, Gesche K; Dünnes, Nadia; Nieder-Röhrmann, Anika; Shalamova, Lyudmila A; Fricke, Markus; Hofacker, Ivo; Höner Zu Siederdissen, Christian; Marz, Manja; Niepmann, Michael

2017-02-01

We have analyzed the binding of the liver-specific microRNA-122 (miR-122) to three conserved target sites of hepatitis C virus (HCV) RNA, two in the non-structural protein 5B (NS5B) coding region and one in the 3' untranslated region (3'UTR). miR-122 binding efficiency strongly depends on target site accessibility under conditions when the range of flanking sequences available for the formation of local RNA secondary structures changes. Our results indicate that the particular sequence feature that contributes most to the correlation between target site accessibility and binding strength varies between different target sites. This suggests that the dynamics of miRNA/Ago2 binding not only depends on the target site itself but also on flanking sequence context to a considerable extent, in particular in a small viral genome in which strong selection constraints act on coding sequence and overlapping cis-signals and model the accessibility of cis-signals. In full-length genomes, single and combination mutations in the miR-122 target sites reveal that site 5B.2 is positively involved in regulating overall genome replication efficiency, whereas mutation of site 5B.3 showed a weaker effect. Mutation of the 3'UTR site and double or triple mutants showed no significant overall effect on genome replication, whereas in a translation reporter RNA, the 3'UTR target site inhibits translation directed by the HCV 5'UTR. Thus, the miR-122 target sites in the 3'-region of the HCV genome are involved in a complex interplay in regulating different steps of the HCV replication cycle.
cis-acting RNA elements required for replication of bovine viral diarrhea virus-hepatitis C virus 5' nontranslated region chimeras.

PubMed Central

Frolov, I; McBride, M S; Rice, C M

1998-01-01

Pestiviruses, such as bovine viral diarrhea virus (BVDV), share many similarities with hepatitis C virus (HCV) yet are more amenable to virologic and genetic analysis. For both BVDV and HCV, translation is initiated via an internal ribosome entry site (IRES). Besides IRES function, the viral 5' nontranslated regions (NTRs) may also contain cis-acting RNA elements important for viral replication. A series of chimeric RNAs were used to examine the function of the BVDV 5' NTR. Our results show that: (1) the HCV and the encephalomyocarditis virus (EMCV) IRES element can functionally replace that of BVDV; (2) two 5' terminal hairpins in BVDV genomic RNA are important for efficient replication; (3) replacement of the entire BVDV 5' NTR with those of HCV or EMCV leads to severely impaired replication; (4) such replacement chimeras are unstable and efficiently replicating pseudorevertants arise; (5) pseudorevertant mutations involve deletion of 5' sequences and/or acquisition of novel 5' sequences such that the 5' terminal 3-4 bases of BVDV genome RNA are restored. Besides providing new insight into functional elements in the BVDV 5' NTR, these chimeras may prove useful as pestivirus vaccines and for screening and evaluation of anti-HCV IRES antivirals. PMID:9814762

RBM24 stabilizes hepatitis B virus pregenomic RNA but inhibits core protein translation by targeting the terminal redundancy sequence.

PubMed

Yao, Yongxuan; Yang, Bo; Cao, Huang; Zhao, Kaitao; Yuan, Yifei; Chen, Yingshan; Zhang, Zhenhua; Wang, Yun; Pei, Rongjuan; Chen, Jizheng; Hu, Xue; Zhou, Yuan; Lu, Mengji; Wu, Chunchen; Chen, Xinwen

2018-05-14

The terminal redundancy (TR) sequence of the 3.5-kb hepatitis B virus (HBV) RNA contains sites that govern many crucial functions in the viral life cycle, including polyadenylation, translation, RNA packaging, and DNA synthesis. In the present study, RNA-binding motif protein 24 (RBM24) is shown to be involved in the modulation of HBV replication by targeting the TR of HBV RNA. In HBV-transfected hepatoma cell lines, both knockdown and overexpression of RBM24 led to decreased HBV replication and transcription. Ectopic expression of RBM24 inhibited HBV replication, which was partly restored by knockdown of RBM24, indicating that a proper level of RBM24 was required for HBV replication. The regulation of RBM24 of HBV replication and translation was achieved by the interaction between the RNA-binding domains of RBM24 and both the 5' and 3' TR of 3.5-kb RNA. RBM24 interacted with the 5' TR of HBV pregenomic RNA (pgRNA) to block 80S ribosome assembly on HBV pgRNA and thus inhibited core protein translation, whereas the interaction between RBM24 and the 3' TR enhanced the stability of HBV RNA. Finally, the regulatory function of RBM24 on HBV replication was further confirmed in a HBV infection model. In conclusion, the present study demonstrates the dual functions of RBM24 by interacting with different TRs of viral RNA and reveals that RBM24 is an important host gene for HBV replication.
Multiple conformational states of DnaA protein regulate its interaction with DnaA boxes in the initiation of DNA replication.

PubMed

Patel, Meera J; Bhatia, Lavesh; Yilmaz, Gulden; Biswas-Fiss, Esther E; Biswas, Subhasis B

2017-09-01

DnaA protein is the initiator of genomic DNA replication in prokaryotes. It binds to specific DNA sequences in the origin of DNA replication and unwinds small AT-rich sequences downstream for the assembly of the replisome. The mechanism of activation of DnaA that enables it to bind and organize the origin DNA and leads to replication initiation remains unclear. In this study, we have developed double-labeled fluorescent DnaA probes to analyze conformational states of DnaA protein upon binding DNA, nucleotide, and Soj sporulation protein using Fluorescence Resonance Energy Transfer (FRET). Our studies demonstrate that DnaA protein undergoes large conformational changes upon binding to substrates and there are multiple distinct conformational states that enable it to initiate DNA replication. DnaA protein adopted a relaxed conformation by expanding ~15Å upon binding ATP and DNA to form the ATP·DnaA·DNA complex. Hydrolysis of bound ATP to ADP led to a contraction of DnaA within the complex. The relaxed conformation of DnaA is likely required for the formation of the multi-protein ATP·DnaA·DNA complex. In the initiation of sporulation, Soj binding to DnaA prevented relaxation of its conformation. Soj·ADP appeared to block the activation of DnaA, suggesting a mechanism for Soj·ADP in switching initiation of DNA replication to sporulation. Our studies demonstrate that multiple conformational states of DnaA protein regulate its binding to DNA in the initiation of DNA replication. Copyright © 2017 Elsevier B.V. All rights reserved.
Break-induced replication and recombinational telomere elongation in yeast.

PubMed

McEachern, Michael J; Haber, James E

2006-01-01

When a telomere becomes unprotected or if only one end of a chromosomal double-strand break succeeds in recombining with a template sequence, DNA can be repaired by a recombination-dependent DNA replication process termed break-induced replication (BIR). In budding yeasts, there are two BIR pathways, one dependent on the Rad51 recombinase protein and one Rad51 independent; these two repair processes lead to different types of survivors in cells lacking the telomerase enzyme that is required for normal telomere maintenance. Recombination at telomeres is triggered by either excessive telomere shortening or disruptions in the function of telomere-binding proteins. Telomere elongation by BIR appears to often occur through a "roll and spread" mechanism. In this process, a telomeric circle produced by recombination at a dysfunctional telomere acts as a template for a rolling circle BIR event to form an elongated telomere. Additional BIR events can then copy the elongated sequence to all other telomeres.
Using nearly full-genome HIV sequence data improves phylogeny reconstruction in a simulated epidemic

PubMed Central

Yebra, Gonzalo; Hodcroft, Emma B.; Ragonnet-Cronin, Manon L.; Pillay, Deenan; Brown, Andrew J. Leigh; Fraser, Christophe; Kellam, Paul; de Oliveira, Tulio; Dennis, Ann; Hoppe, Anne; Kityo, Cissy; Frampton, Dan; Ssemwanga, Deogratius; Tanser, Frank; Keshani, Jagoda; Lingappa, Jairam; Herbeck, Joshua; Wawer, Maria; Essex, Max; Cohen, Myron S.; Paton, Nicholas; Ratmann, Oliver; Kaleebu, Pontiano; Hayes, Richard; Fidler, Sarah; Quinn, Thomas; Novitsky, Vladimir; Haywards, Andrew; Nastouli, Eleni; Morris, Steven; Clark, Duncan; Kozlakidis, Zisis

2016-01-01

HIV molecular epidemiology studies analyse viral pol gene sequences due to their availability, but whole genome sequencing allows to use other genes. We aimed to determine what gene(s) provide(s) the best approximation to the real phylogeny by analysing a simulated epidemic (created as part of the PANGEA_HIV project) with a known transmission tree. We sub-sampled a simulated dataset of 4662 sequences into different combinations of genes (gag-pol-env, gag-pol, gag, pol, env and partial pol) and sampling depths (100%, 60%, 20% and 5%), generating 100 replicates for each case. We built maximum-likelihood trees for each combination using RAxML (GTR + Γ), and compared their topologies to the corresponding true tree’s using CompareTree. The accuracy of the trees was significantly proportional to the length of the sequences used, with the gag-pol-env datasets showing the best performance and gag and partial pol sequences showing the worst. The lowest sampling depths (20% and 5%) greatly reduced the accuracy of tree reconstruction and showed high variability among replicates, especially when using the shortest gene datasets. In conclusion, using longer sequences derived from nearly whole genomes will improve the reliability of phylogenetic reconstruction. With low sample coverage, results can be highly variable, particularly when based on short sequences. PMID:28008945
Using nearly full-genome HIV sequence data improves phylogeny reconstruction in a simulated epidemic.

PubMed

Yebra, Gonzalo; Hodcroft, Emma B; Ragonnet-Cronin, Manon L; Pillay, Deenan; Brown, Andrew J Leigh

2016-12-23

HIV molecular epidemiology studies analyse viral pol gene sequences due to their availability, but whole genome sequencing allows to use other genes. We aimed to determine what gene(s) provide(s) the best approximation to the real phylogeny by analysing a simulated epidemic (created as part of the PANGEA_HIV project) with a known transmission tree. We sub-sampled a simulated dataset of 4662 sequences into different combinations of genes (gag-pol-env, gag-pol, gag, pol, env and partial pol) and sampling depths (100%, 60%, 20% and 5%), generating 100 replicates for each case. We built maximum-likelihood trees for each combination using RAxML (GTR + Γ), and compared their topologies to the corresponding true tree's using CompareTree. The accuracy of the trees was significantly proportional to the length of the sequences used, with the gag-pol-env datasets showing the best performance and gag and partial pol sequences showing the worst. The lowest sampling depths (20% and 5%) greatly reduced the accuracy of tree reconstruction and showed high variability among replicates, especially when using the shortest gene datasets. In conclusion, using longer sequences derived from nearly whole genomes will improve the reliability of phylogenetic reconstruction. With low sample coverage, results can be highly variable, particularly when based on short sequences.
Metagenomic characterization of airborne viral DNA diversity in the near-surface atmosphere.

PubMed

Whon, Tae Woong; Kim, Min-Soo; Roh, Seong Woon; Shin, Na-Ri; Lee, Hae-Won; Bae, Jin-Woo

2012-08-01

Airborne viruses are expected to be ubiquitous in the atmosphere but they still remain poorly understood. This study investigated the temporal and spatial dynamics of airborne viruses and their genotypic characteristics in air samples collected from three distinct land use types (a residential district [RD], a forest [FR], and an industrial complex [IC]) and from rainwater samples freshly precipitated at the RD site (RD-rain). Viral abundance exhibited a seasonal fluctuation in the range between 1.7 × 10(6) and 4.0 × 10(7) viruses m(-3), which increased from autumn to winter and decreased toward spring, but no significant spatial differences were observed. Temporal variations in viral abundance were inversely correlated with seasonal changes in temperature and absolute humidity. Metagenomic analysis of air viromes amplified by rolling-circle phi29 polymerase-based random hexamer priming indicated the dominance of plant-associated single-stranded DNA (ssDNA) geminivirus-related viruses, followed by animal-infecting circovirus-related sequences, with low numbers of nanoviruses and microphages-related genomes. Particularly, the majority of the geminivirus-related viruses were closely related to ssDNA mycoviruses that infect plant-pathogenic fungi. Phylogenetic analysis based on the replication initiator protein sequence indicated that the airborne ssDNA viruses were distantly related to known ssDNA viruses, suggesting that a high diversity of viruses were newly discovered. This research is the first to report the seasonality of airborne viruses and their genetic diversity, which enhances our understanding of viral ecology in temperate regions.
Metagenomic Characterization of Airborne Viral DNA Diversity in the Near-Surface Atmosphere

PubMed Central

Whon, Tae Woong; Kim, Min-Soo; Roh, Seong Woon; Shin, Na-Ri; Lee, Hae-Won

2012-01-01

Airborne viruses are expected to be ubiquitous in the atmosphere but they still remain poorly understood. This study investigated the temporal and spatial dynamics of airborne viruses and their genotypic characteristics in air samples collected from three distinct land use types (a residential district [RD], a forest [FR], and an industrial complex [IC]) and from rainwater samples freshly precipitated at the RD site (RD-rain). Viral abundance exhibited a seasonal fluctuation in the range between 1.7 × 106 and 4.0 × 107 viruses m−3, which increased from autumn to winter and decreased toward spring, but no significant spatial differences were observed. Temporal variations in viral abundance were inversely correlated with seasonal changes in temperature and absolute humidity. Metagenomic analysis of air viromes amplified by rolling-circle phi29 polymerase-based random hexamer priming indicated the dominance of plant-associated single-stranded DNA (ssDNA) geminivirus-related viruses, followed by animal-infecting circovirus-related sequences, with low numbers of nanoviruses and microphages-related genomes. Particularly, the majority of the geminivirus-related viruses were closely related to ssDNA mycoviruses that infect plant-pathogenic fungi. Phylogenetic analysis based on the replication initiator protein sequence indicated that the airborne ssDNA viruses were distantly related to known ssDNA viruses, suggesting that a high diversity of viruses were newly discovered. This research is the first to report the seasonality of airborne viruses and their genetic diversity, which enhances our understanding of viral ecology in temperate regions. PMID:22623790
A test of the transcription model for biased inheritance of yeast mitochondrial DNA.

PubMed

Lorimer, H E; Brewer, B J; Fangman, W L

1995-09-01

Two strand-specific origins of replication appear to be required for mammalian mitochondrial DNA (mtDNA) replication. Structural equivalents of these origins are found in the rep sequences of Saccharomyces cerevisiae mtDNA. These striking similarities have contributed to a universal model for the initiation of mtDNA replication in which a primer is created by cleavage of an origin region transcript. Consistent with this model are the properties of deletion mutants of yeast mtDNA ([rho-]) with a high density of reps (HS [rho-]). These mutant mtDNAs are preferentially inherited by the progeny resulting from the mating of HS [rho-] cells with cells containing wild-type mtDNA ([rho+]). This bias is presumed to result from a replication advantage conferred on HS [rho-] mtDNA by the high density of rep sequences acting as origins. To test whether transcription is indeed required for the preferential inheritance of HS [rho-] mtDNA, we deleted the nuclear gene (RPO41) for the mitochondrial RNA polymerase, reducing transcripts by at least 1000-fold. Since [rho-] genomes, but not [rho+] genomes, are stable when RPO41 is deleted, we examined matings between HS [rho-] and neutral [rho-] cells. Neutral [rho-] mtDNAs lack rep sequences and are not preferentially inherited in [rho-] x [rho+] crosses. In HS [rho-] x neutral [rho-] matings, the HS [rho-] mtDNA was preferentially inherited whether both parents were wild type or both were deleted for RPO41. Thus, transcription from the rep promoter does not appear to be necessary for biased inheritance. Our results, and analysis of the literature, suggest that priming by transcription is not a universal mechanism for mtDNA replication initiation.
Genome-wide mapping of nuclear mitochondrial DNA sequences links DNA replication origins to chromosomal double-strand break formation in Schizosaccharomyces pombe

PubMed Central

Lenglez, Sandrine; Hermand, Damien; Decottignies, Anabelle

2010-01-01

Chromosomal double-strand breaks (DSBs) threaten genome integrity and repair of these lesions is often mutagenic. How and where DSBs are formed is a major question conveniently addressed in simple model organisms like yeast. NUMTs, nuclear DNA sequences of mitochondrial origin, are present in most eukaryotic genomes and probably result from the capture of mitochondrial DNA (mtDNA) fragments into chromosomal breaks. NUMT formation is ongoing and was reported to cause de novo human genetic diseases. Study of NUMTs is likely to contribute to the understanding of naturally occurring chromosomal breaks. We show that Schizosaccharomyces pombe NUMTs are exclusively located in noncoding regions with no preference for gene promoters and, when located into promoters, do not affect gene transcription level. Strikingly, most noncoding regions comprising NUMTs are also associated with a DNA replication origin (ORI). Chromatin immunoprecipitation experiments revealed that chromosomal NUMTs are probably not acting as ORI on their own but that mtDNA insertions occurred directly next to ORIs, suggesting that these loci may be prone to DSB formation. Accordingly, induction of excessive DNA replication origin firing, a phenomenon often associated with human tumor formation, resulted in frequent nucleotide deletion events within ORI3001 subtelomeric chromosomal locus, illustrating a novel aspect of DNA replication-driven genomic instability. How mtDNA is fragmented is another important issue that we addressed by sequencing experimentally induced NUMTs. This highlighted regions of S. pombe mtDNA prone to breaking. Together with an analysis of human NUMTs, we propose that these fragile sites in mtDNA may correspond to replication pause sites. PMID:20688779
Mutagenic Spectra Arising from Replication Bypass of the 2,6-diamino-4-hydroxy-N5-methyl Formamidopyrimidine Adduct in Primate Cells

PubMed Central

Earley, Lauriel F.; Minko, Irina G.; Christov, Plamen P.; Rizzo, Carmelo J.; Lloyd, R. Stephen

2013-01-01

DNA exposures to electrophilic methylating agents that are commonly used during chemotherapeutic treatments cause diverse chemical modifications of nucleobases, with reaction at N7-dG being the most abundant. Although this base modification frequently results in destabilization of the glycosyl bond and spontaneous depurination, the adduct can react with hydroxide ion to yield a stable, ring-opened MeFapy-dG and this lesion has been reported to persist in animal tissues. Results from prior in vitro replication bypass investigations of the MeFapy-dG adduct had revealed complex spectra of replication errors that differed depending on the identity of DNA polymerase and the local sequence context. In this study, a series of nine site-specifically modified MeFapy-dG-containing oligodeoxynucleotides were engineered into a shuttle vector and subjected to replication in primate cells. In all nine sequence contexts examined, MeFapy-dG was shown to be associated with a strong mutator phenotype, predominantly causing base substitutions, with G to T transversions being most common. Single and dinucleotide deletions were also found in a subset of the sequence contexts. Interestingly, single-nucleotide deletions occurred not only at the adducted site, but also one nucleotide downstream of the adduct. Standard models for primer-template misalignment could account for some, but not all mutations observed. These data demonstrate that in addition to mutagenesis predicted from replication of DNAs containing O6-Me-dG and O4-Me-dT, the MeFapy-dG adduct likely contributes to mutagenic events following chemotherapeutic treatments. PMID:23763662
Clinical and molecular features of human rhinovirus C

PubMed Central

Bochkov, Yury A.; Gern, James E.

2012-01-01

A newly discovered group of human rhinoviruses (HRVs) has been classified as the HRV-C species based on distinct genomic features. HRV-Cs circulate worldwide, and are important causes of upper and lower respiratory illnesses. Methods to culture and produce these viruses have recently been developed, and should enable identification of unique features of HRV-C replication and biology. PMID:22285901
Replication and Comparison of the Newly Proposed ADOS-2, Module 4 Algorithm in ASD without ID: A Multi-Site Study

ERIC Educational Resources Information Center

Pugliese, Cara E.; Kenworthy, Lauren; Bal, Vanessa Hus; Wallace, Gregory L.; Yerys, Benjamin E.; Maddox, Brenna B.; White, Susan W.; Popal, Haroon; Armour, Anna Chelsea; Miller, Judith; Herrington, John D.; Schultz, Robert T.; Martin, Alex; Anthony, Laura Gutermuth

2015-01-01

Recent updates have been proposed to the Autism Diagnostic Observation Schedule-2 Module 4 diagnostic algorithm. This new algorithm, however, has not yet been validated in an independent sample without intellectual disability (ID). This multi-site study compared the original and revised algorithms in individuals with ASD without ID. The revised…
Novel Approaches Reveal that Toxoplasma gondii Bradyzoites within Tissue Cysts Are Dynamic and Replicating Entities In Vivo.

PubMed

Watts, Elizabeth; Zhao, Yihua; Dhara, Animesh; Eller, Becca; Patwardhan, Abhijit; Sinai, Anthony P

2015-09-08

Despite their critical role in chronic toxoplasmosis, the biology of Toxoplasma gondii bradyzoites is poorly understood. In an attempt to address this gap, we optimized approaches to purify tissue cysts and analyzed the replicative potential of bradyzoites within these cysts. In order to quantify individual bradyzoites within tissue cysts, we have developed imaging software, BradyCount 1.0, that allows the rapid establishment of bradyzoite burdens within imaged optical sections of purified tissue cysts. While in general larger tissue cysts contain more bradyzoites, their relative "occupancy" was typically lower than that of smaller cysts, resulting in a lower packing density. The packing density permits a direct measure of how bradyzoites develop within cysts, allowing for comparisons across progression of the chronic phase. In order to capture bradyzoite endodyogeny, we exploited the differential intensity of TgIMC3, an inner membrane complex protein that intensely labels newly formed/forming daughters within bradyzoites and decays over time in the absence of further division. To our surprise, we were able to capture not only sporadic and asynchronous division but also synchronous replication of all bradyzoites within mature tissue cysts. Furthermore, the time-dependent decay of TgIMC3 intensity was exploited to gain insights into the temporal patterns of bradyzoite replication in vivo. Despite the fact that bradyzoites are considered replicatively dormant, we find evidence for cyclical, episodic bradyzoite growth within tissue cysts in vivo. These findings directly challenge the prevailing notion of bradyzoites as dormant nonreplicative entities in chronic toxoplasmosis and have implications on our understanding of this enigmatic and clinically important life cycle stage. The protozoan Toxoplasma gondii establishes a lifelong chronic infection mediated by the bradyzoite form of the parasite within tissue cysts. Technical challenges have limited even the most basic studies on bradyzoites and the tissue cysts in vivo. Bradyzoites, which are viewed as dormant, poorly replicating or nonreplicating entities, were found to be surprisingly active, exhibiting not only the capacity for growth but also previously unrecognized patterns of replication that point to their being considerably more dynamic than previously imagined. These newly revealed properties force us to reexamine the most basic questions regarding bradyzoite biology and the progression of the chronic phase of toxoplasmosis. By developing new tools and approaches to study the chronic phase at the level of bradyzoites, we expose new avenues to tackle both drug development and a better understanding of events that may lead to reactivated symptomatic disease. Copyright © 2015 Watts et al.
Cell-Free, De Nova Synthesis of Poliovirus

NASA Astrophysics Data System (ADS)

Molla, Akhteruzzaman; Paul, Aniko V.; Wimmer, Eckard

1991-12-01

Cell-free translation of poliovirus RNA in an extract of uninfected human (HeLa) cells yielded viral proteins through proteolysis of the polyprotein. In the extract, newly synthesized proteins catalyzed poliovirus-specific RNA synthesis, and formed infectious poliovirus de novo. Newly formed virions were neutralized by type-specific antiserum, and infection of human cells with them was prevented by poliovirus receptor-specific antibodies. Poliovirus synthesis was increased nearly 70-fold when nucleoside triphosphates were added, but it was abolished in the presence of inhibitors of translation or viral genome replication. The ability to conduct cell-free synthesis of poliovirus will aid in the study of picornavirus proliferation and in the search for the control of picornaviral disease.
DNA replication origins—where do we begin?

PubMed Central

Prioleau, Marie-Noëlle; MacAlpine, David M.

2016-01-01

For more than three decades, investigators have sought to identify the precise locations where DNA replication initiates in mammalian genomes. The development of molecular and biochemical approaches to identify start sites of DNA replication (origins) based on the presence of defining and characteristic replication intermediates at specific loci led to the identification of only a handful of mammalian replication origins. The limited number of identified origins prevented a comprehensive and exhaustive search for conserved genomic features that were capable of specifying origins of DNA replication. More recently, the adaptation of origin-mapping assays to genome-wide approaches has led to the identification of tens of thousands of replication origins throughout mammalian genomes, providing an unprecedented opportunity to identify both genetic and epigenetic features that define and regulate their distribution and utilization. Here we summarize recent advances in our understanding of how primary sequence, chromatin environment, and nuclear architecture contribute to the dynamic selection and activation of replication origins across diverse cell types and developmental stages. PMID:27542827
Replication landscape of the human genome

PubMed Central

Petryk, Nataliya; Kahli, Malik; d'Aubenton-Carafa, Yves; Jaszczyszyn, Yan; Shen, Yimin; Silvain, Maud; Thermes, Claude; Chen, Chun-Long; Hyrien, Olivier

2016-01-01

Despite intense investigation, human replication origins and termini remain elusive. Existing data have shown strong discrepancies. Here we sequenced highly purified Okazaki fragments from two cell types and, for the first time, quantitated replication fork directionality and delineated initiation and termination zones genome-wide. Replication initiates stochastically, primarily within non-transcribed, broad (up to 150 kb) zones that often abut transcribed genes, and terminates dispersively between them. Replication fork progression is significantly co-oriented with the transcription. Initiation and termination zones are frequently contiguous, sometimes separated by regions of unidirectional replication. Initiation zones are enriched in open chromatin and enhancer marks, even when not flanked by genes, and often border ‘topologically associating domains' (TADs). Initiation zones are enriched in origin recognition complex (ORC)-binding sites and better align to origins previously mapped using bubble-trap than λ-exonuclease. This novel panorama of replication reveals how chromatin and transcription modulate the initiation process to create cell-type-specific replication programs. PMID:26751768
Analysis of JC virus DNA replication using a quantitative and high-throughput assay

PubMed Central

Shin, Jong; Phelan, Paul J.; Chhum, Panharith; Bashkenova, Nazym; Yim, Sung; Parker, Robert; Gagnon, David; Gjoerup, Ole; Archambault, Jacques; Bullock, Peter A.

2015-01-01

Progressive Multifocal Leukoencephalopathy (PML) is caused by lytic replication of JC virus (JCV) in specific cells of the central nervous system. Like other polyomaviruses, JCV encodes a large T-antigen helicase needed for replication of the viral DNA. Here, we report the development of a luciferase-based, quantitative and high-throughput assay of JCV DNA replication in C33A cells, which, unlike the glial cell lines Hs 683 and U87, accumulate high levels of nuclear T-ag needed for robust replication. Using this assay, we investigated the requirement for different domains of T-ag, and for specific sequences within and flanking the viral origin, in JCV DNA replication. Beyond providing validation of the assay, these studies revealed an important stimulatory role of the transcription factor NF1 in JCV DNA replication. Finally, we show that the assay can be used for inhibitor testing, highlighting its value for the identification of antiviral drugs targeting JCV DNA replication. PMID:25155200
Novel Chromosome Organization Pattern in Actinomycetales-Overlapping Replication Cycles Combined with Diploidy.

PubMed

Böhm, Kati; Meyer, Fabian; Rhomberg, Agata; Kalinowski, Jörn; Donovan, Catriona; Bramkamp, Marc

2017-06-06

Bacteria regulate chromosome replication and segregation tightly with cell division to ensure faithful segregation of DNA to daughter generations. The underlying mechanisms have been addressed in several model species. It became apparent that bacteria have evolved quite different strategies to regulate DNA segregation and chromosomal organization. We have investigated here how the actinobacterium Corynebacterium glutamicum organizes chromosome segregation and DNA replication. Unexpectedly, we found that C. glutamicum cells are at least diploid under all of the conditions tested and that these organisms have overlapping C periods during replication, with both origins initiating replication simultaneously. On the basis of experimental data, we propose growth rate-dependent cell cycle models for C. glutamicum IMPORTANCE Bacterial cell cycles are known for few model organisms and can vary significantly between species. Here, we studied the cell cycle of Corynebacterium glutamicum , an emerging cell biological model organism for mycolic acid-containing bacteria, including mycobacteria. Our data suggest that C. glutamicum carries two pole-attached chromosomes that replicate with overlapping C periods, thus initiating a new round of DNA replication before the previous one is terminated. The newly replicated origins segregate to midcell positions, where cell division occurs between the two new origins. Even after long starvation or under extremely slow-growth conditions, C. glutamicum cells are at least diploid, likely as an adaptation to environmental stress that may cause DNA damage. The cell cycle of C. glutamicum combines features of slow-growing organisms, such as polar origin localization, and fast-growing organisms, such as overlapping C periods. Copyright © 2017 Böhm et al.
Hsp70 Isoforms Are Essential for the Formation of Kaposi’s Sarcoma-Associated Herpesvirus Replication and Transcription Compartments

PubMed Central

Baquero-Pérez, Belinda; Whitehouse, Adrian

2015-01-01

Kaposi’s sarcoma-associated herpesvirus (KSHV) is an oncogenic herpesvirus associated with various AIDS-related malignancies. Like other herpesviruses, multiple processes required for KSHV lytic replication, including viral transcription, viral DNA synthesis and capsid assembly occur in virus-induced intranuclear structures, termed replication and transcription compartments (RTCs). Here we utilised a novel methodology, combining subcellular fractionation and quantitative proteomics, to identify cellular proteins which are recruited to KSHV-induced RTCs and thus play a key role in KSHV lytic replication. We show that several isoforms of the HSP70 chaperone family, Hsc70 and iHsp70, are redistributed from the cytoplasm into the nucleus coinciding with the initial formation of KSHV-induced RTCs. We demonstrate that nuclear chaperone foci are dynamic, initially forming adjacent to newly formed KSHV RTCs, however during later time points the chaperones move within KSHV RTCs and completely co-localise with actively replicating viral DNA. The functional significance of Hsp70 isoforms recruitment into KSHV RTCs was also examined using the specific Hsp70 isoform small molecule inhibitor, VER-155008. Intriguingly, results highlight an essential role of Hsp70 isoforms in the KSHV replication cycle independent of protein stability and maturation. Notably, inhibition of Hsp70 isoforms precluded KSHV RTC formation and RNA polymerase II (RNAPII) relocalisation to the viral genome leading to the abolishment of global KSHV transcription and subsequent viral protein synthesis and DNA replication. These new findings have revealed novel mechanisms that regulate KSHV lytic replication and highlight the potential of HSP70 inhibitors as novel antiviral agents. PMID:26587836
SL1 revisited: functional analysis of the structure and conformation of HIV-1 genome RNA.

PubMed

Sakuragi, Sayuri; Yokoyama, Masaru; Shioda, Tatsuo; Sato, Hironori; Sakuragi, Jun-Ichi

2016-11-11

The dimer initiation site/dimer linkage sequence (DIS/DLS) region of HIV is located on the 5' end of the viral genome and suggested to form complex secondary/tertiary structures. Within this structure, stem-loop 1 (SL1) is believed to be most important and an essential key to dimerization, since the sequence and predicted secondary structure of SL1 are highly stable and conserved among various virus subtypes. In particular, a six-base palindromic sequence is always present at the hairpin loop of SL1 and the formation of kissing-loop structure at this position between the two strands of genomic RNA is suggested to trigger dimerization. Although the higher-order structure model of SL1 is well accepted and perhaps even undoubted lately, there could be stillroom for consideration to depict the functional SL1 structure while in vivo (in virion or cell). In this study, we performed several analyses to identify the nucleotides and/or basepairing within SL1 which are necessary for HIV-1 genome dimerization, encapsidation, recombination and infectivity. We unexpectedly found that some nucleotides that are believed to contribute the formation of the stem do not impact dimerization or infectivity. On the other hand, we found that one G-C basepair involved in stem formation may serve as an alternative dimer interactive site. We also report on our further investigation of the roles of the palindromic sequences on viral replication. Collectively, we aim to assemble a more-comprehensive functional map of SL1 on the HIV-1 viral life cycle. We discovered several possibilities for a novel structure of SL1 in HIV-1 DLS. The newly proposed structure model suggested that the hairpin loop of SL1 appeared larger, and genome dimerization process might consist of more complicated mechanism than previously understood. Further investigations would be still required to fully understand the genome packaging and dimerization of HIV.

Distinguishing the genotype 1 genes and proteins of human Wa-like rotaviruses vs. porcine rotaviruses

PubMed Central

Silva, Fernanda D.F.; Gregori, F.; McDonald, Sarah M.

2016-01-01

Group A rotaviruses (RVAs) are 11-segmented, double-stranded RNA viruses and important causes of gastroenteritis in the young of many animal species. Previous studies have suggested that human Wa-like RVAs share a close evolutionary relationship with porcine RVAs. Specifically, the VP1-VP3 and NSP2-5/6 genes of these viruses are usually classified as genotype 1 with >81% nucleotide sequence identity. Yet, it remains unknown whether the genotype 1 genes and proteins of human Wa-like strains are distinguishable from those of porcine strains. To investigate this, we performed comprehensive bioinformatic analyses using all known genotype 1 gene sequences. The RVAs analyzed represent wildtype strains isolated from humans or pigs at various geographical locations during the years of 2004–2013, including 11 newly-sequenced porcine RVAs from Brazil. We also analyzed archival strains that were isolated during the years of 1977–1992 as well as atypical strains involved in inter-species transmission between humans and pigs. We found that, in general, the genotype 1 genes of typical modern human Wa-like RVAs clustered together in phylogenetic trees and were separate from those of typical modern porcine RVAs. The only exception was for the NSP5/6 gene, which showed no host-specific phylogenetic clustering. Using amino acid sequence alignments, we identified 34 positions that differentiated the VP1-VP3, NSP2, and NSP3 genotype 1 proteins of typical modern human Wa-like RVAs versus typical modern porcine RVAs and documented how these positions vary in the archival/unusual isolates. No host-specific amino acid positions were identified for NSP4, NSP5, or NSP6. Altogether, the results of this study support the notion that human Wa-like RVAs and porcine RVAs are evolutionarily related, but indicate that some of their genotype 1 genes and proteins have diverged over time possibly as a reflection of sequestered replication and protein co-adaptation in their respective hosts. PMID:27180895
Whole-Exome Sequencing in Familial Parkinson Disease

PubMed Central

Farlow, Janice L.; Robak, Laurie A.; Hetrick, Kurt; Bowling, Kevin; Boerwinkle, Eric; Coban-Akdemir, Zeynep H.; Gambin, Tomasz; Gibbs, Richard A.; Gu, Shen; Jain, Preti; Jankovic, Joseph; Jhangiani, Shalini; Kaw, Kaveeta; Lai, Dongbing; Lin, Hai; Ling, Hua; Liu, Yunlong; Lupski, James R.; Muzny, Donna; Porter, Paula; Pugh, Elizabeth; White, Janson; Doheny, Kimberly; Myers, Richard M.; Shulman, Joshua M.; Foroud, Tatiana

2016-01-01

IMPORTANCE Parkinson disease (PD) is a progressive neurodegenerative disease for which susceptibility is linked to genetic and environmental risk factors. OBJECTIVE To identify genetic variants contributing to disease risk in familial PD. DESIGN, SETTING, AND PARTICIPANTS A 2-stage study design that included a discovery cohort of families with PD and a replication cohort of familial probands was used. In the discovery cohort, rare exonic variants that segregated in multiple affected individuals in a family and were predicted to be conserved or damaging were retained. Genes with retained variants were prioritized if expressed in the brain and located within PD-relevant pathways. Genes in which prioritized variants were observed in at least 4 families were selected as candidate genes for replication in the replication cohort. The setting was among individuals with familial PD enrolled from academic movement disorder specialty clinics across the United States. All participants had a family history of PD. MAIN OUTCOMES AND MEASURES Identification of genes containing rare, likely deleterious, genetic variants in individuals with familial PD using a 2-stage exome sequencing study design. RESULTS The 93 individuals from 32 families in the discovery cohort (49.5% [46 of 93] female) had a mean (SD) age at onset of 61.8 (10.0) years. The 49 individuals with familial PD in the replication cohort (32.6% [16 of 49] female) had a mean (SD) age at onset of 50.1 (15.7) years. Discovery cohort recruitment dates were 1999 to 2009, and replication cohort recruitment dates were 2003 to 2014. Data analysis dates were 2011 to 2015. Three genes containing a total of 13 rare and potentially damaging variants were prioritized in the discovery cohort. Two of these genes (TNK2 and TNR) also had rare variants that were predicted to be damaging in the replication cohort. All 9 variants identified in the 2 replicated genes in 12 families across the discovery and replication cohorts were confirmed via Sanger sequencing. CONCLUSIONS AND RELEVANCE TNK2 and TNR harbored rare, likely deleterious, variants in individuals having familial PD, with similar findings in an independent cohort. To our knowledge, these genes have not been previously associated with PD, although they have been linked to critical neuronal functions. Further studies are required to confirm a potential role for these genes in the pathogenesis of PD. PMID:26595808
Plum Pox Virus 6K1 Protein Is Required for Viral Replication and Targets the Viral Replication Complex at the Early Stage of Infection.

PubMed

Cui, Hongguang; Wang, Aiming

2016-05-15

The potyviral RNA genome encodes two polyproteins that are proteolytically processed by three viral protease domains into 11 mature proteins. Extensive molecular studies have identified functions for the majority of the viral proteins. For example, 6K2, one of the two smallest potyviral proteins, is an integral membrane protein and induces the endoplasmic reticulum (ER)-originated replication vesicles that target the chloroplast for robust viral replication. However, the functional role of 6K1, the other smallest protein, remains uncharacterized. In this study, we developed a series of recombinant full-length viral cDNA clones derived from a Canadian Plum pox virus (PPV) isolate. We found that deletion of any of the short motifs of 6K1 (each of which ranged from 5 to 13 amino acids), most of the 6K1 sequence (but with the conserved sequence of the cleavage sites being retained), or all of the 6K1 sequence in the PPV infectious clone abolished viral replication. The trans expression of 6K1 or the cis expression of a dislocated 6K1 failed to rescue the loss-of-replication phenotype, suggesting the temporal and spatial requirement of 6K1 for viral replication. Disruption of the N- or C-terminal cleavage site of 6K1, which prevented the release of 6K1 from the polyprotein, either partially or completely inhibited viral replication, suggesting the functional importance of the mature 6K1. We further found that green fluorescent protein-tagged 6K1 formed punctate inclusions at the viral early infection stage and colocalized with chloroplast-bound viral replicase elements 6K2 and NIb. Taken together, our results suggest that 6K1 is required for viral replication and is an important viral element of the viral replication complex at the early infection stage. Potyviruses account for more than 30% of known plant viruses and consist of many agriculturally important viruses. The genomes of potyviruses encode two polyproteins that are proteolytically processed into 11 mature proteins, with the majority of them having been at least partially functionally characterized. However, the functional role of a small protein named 6K1 remains obscure. In this study, we showed that deletion of 6K1 or a short motif/region of 6K1 in the full-length cDNA clones of plum pox virus abolishes viral replication and that mutation of the N- or C-terminal cleavage sites of 6K1 to prevent its release from the polyprotein greatly attenuates or completely inhibits viral replication, suggesting its important role in potyviral infection. We report that 6K1 forms punctate structures and targets the replication vesicles in PPV-infected plant leaf cells at the early infection stage. Our data reveal that 6K1 is an important viral protein of the potyviral replication complex. Copyright © 2016, American Society for Microbiology. All Rights Reserved.
Community Profiling of Fusarium in Combination with Other Plant-Associated Fungi in Different Crop Species Using SMRT Sequencing.

PubMed

Walder, Florian; Schlaeppi, Klaus; Wittwer, Raphaël; Held, Alain Y; Vogelgsang, Susanne; van der Heijden, Marcel G A

2017-01-01

Fusarium head blight, caused by fungi from the genus Fusarium , is one of the most harmful cereal diseases, resulting not only in severe yield losses but also in mycotoxin contaminated and health-threatening grains. Fusarium head blight is caused by a diverse set of species that have different host ranges, mycotoxin profiles and responses to agricultural practices. Thus, understanding the composition of Fusarium communities in the field is crucial for estimating their impact and also for the development of effective control measures. Up to now, most molecular tools that monitor Fusarium communities on plants are limited to certain species and do not distinguish other plant associated fungi. To close these gaps, we developed a sequencing-based community profiling methodology for crop-associated fungi with a focus on the genus Fusarium . By analyzing a 1600 bp long amplicon spanning the highly variable segments ITS and D1-D3 of the ribosomal operon by PacBio SMRT sequencing, we were able to robustly quantify Fusarium down to species level through clustering against reference sequences. The newly developed methodology was successfully validated in mock communities and provided similar results as the culture-based assessment of Fusarium communities by seed health tests in grain samples from different crop species. Finally, we exemplified the newly developed methodology in a field experiment with a wheat-maize crop sequence under different cover crop and tillage regimes. We analyzed wheat straw residues, cover crop shoots and maize grains and we could reveal that the cover crop hairy vetch ( Vicia villosa ) acts as a potent alternative host for Fusarium (OTU F.ave/tri ) showing an eightfold higher relative abundance compared with other cover crop treatments. Moreover, as the newly developed methodology also allows to trace other crop-associated fungi, we found that vetch and green fallow hosted further fungal plant pathogens including Zymoseptoria tritici . Thus, besides their beneficial traits, cover crops can also entail phytopathological risks by acting as alternative hosts for Fusarium and other noxious plant pathogens. The newly developed sequencing based methodology is a powerful diagnostic tool to trace Fusarium in combination with other fungi associated to different crop species.
Community Profiling of Fusarium in Combination with Other Plant-Associated Fungi in Different Crop Species Using SMRT Sequencing

PubMed Central

Walder, Florian; Schlaeppi, Klaus; Wittwer, Raphaël; Held, Alain Y.; Vogelgsang, Susanne; van der Heijden, Marcel G. A.

2017-01-01

Fusarium head blight, caused by fungi from the genus Fusarium, is one of the most harmful cereal diseases, resulting not only in severe yield losses but also in mycotoxin contaminated and health-threatening grains. Fusarium head blight is caused by a diverse set of species that have different host ranges, mycotoxin profiles and responses to agricultural practices. Thus, understanding the composition of Fusarium communities in the field is crucial for estimating their impact and also for the development of effective control measures. Up to now, most molecular tools that monitor Fusarium communities on plants are limited to certain species and do not distinguish other plant associated fungi. To close these gaps, we developed a sequencing-based community profiling methodology for crop-associated fungi with a focus on the genus Fusarium. By analyzing a 1600 bp long amplicon spanning the highly variable segments ITS and D1–D3 of the ribosomal operon by PacBio SMRT sequencing, we were able to robustly quantify Fusarium down to species level through clustering against reference sequences. The newly developed methodology was successfully validated in mock communities and provided similar results as the culture-based assessment of Fusarium communities by seed health tests in grain samples from different crop species. Finally, we exemplified the newly developed methodology in a field experiment with a wheat-maize crop sequence under different cover crop and tillage regimes. We analyzed wheat straw residues, cover crop shoots and maize grains and we could reveal that the cover crop hairy vetch (Vicia villosa) acts as a potent alternative host for Fusarium (OTU F.ave/tri) showing an eightfold higher relative abundance compared with other cover crop treatments. Moreover, as the newly developed methodology also allows to trace other crop-associated fungi, we found that vetch and green fallow hosted further fungal plant pathogens including Zymoseptoria tritici. Thus, besides their beneficial traits, cover crops can also entail phytopathological risks by acting as alternative hosts for Fusarium and other noxious plant pathogens. The newly developed sequencing based methodology is a powerful diagnostic tool to trace Fusarium in combination with other fungi associated to different crop species. PMID:29234337
Common fragile sites (CFS) and extremely large CFS genes are targets for human papillomavirus integrations and chromosome rearrangements in oropharyngeal squamous cell carcinoma.

PubMed

Gao, Ge; Johnson, Sarah H; Vasmatzis, George; Pauley, Christina E; Tombers, Nicole M; Kasperbauer, Jan L; Smith, David I

2017-01-01

Common fragile sites (CFS) are chromosome regions that are prone to form gaps or breaks in response to DNA replication stress. They are often found as hotspots for sister chromatid exchanges, deletions, and amplifications in different cancers. Many of the CFS regions are found to span genes whose genomic sequence is greater than 1 Mb, some of which have been demonstrated to function as important tumor suppressors. CFS regions are also hotspots for human papillomavirus (HPV) integrations in cervical cancer. We used mate-pair sequencing to examine HPV integration events and chromosomal structural variations in 34 oropharyngeal squamous cell carcinoma (OPSCC). We used endpoint PCR and Sanger sequencing to validate each HPV integration event and found HPV integrations preferentially occurred within CFS regions similar to what is observed in cervical cancer. We also found that many of the chromosomal alterations detected also occurred at or near the cytogenetic location of CFSs. Several large genes were also found to be recurrent targets of rearrangements, independent of HPV integrations, including CSMD1 (2.1Mb), LRP1B (1.9Mb), and LARGE1 (0.7Mb). Sanger sequencing revealed that the nucleotide sequences near to identified junction sites contained repetitive and AT-rich sequences that were shown to have the potential to form stem-loop DNA secondary structures that might stall DNA replication fork progression during replication stress. This could then cause increased instability in these regions which could lead to cancer development in human cells. Our findings suggest that CFSs and some specific large genes appear to play important roles in OPSCC. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.
Does Literacy Skill Level Predict Performance in Community College Courses: A Replication and Extension

ERIC Educational Resources Information Center

Allen, Nancy J.; DeLauro, Kimberly A.; Perry, Julia K.; Carman, Carol A.

2017-01-01

Previous research has found a positive relationship between students who had completed a sequence of developmental reading and writing courses and success in a reading-intensive college-level course. This study replicates and expands upon the previous research of Goldstein and Perin (2008) by utilizing a differently diverse sample and an…
Back to the Origin

PubMed Central

Evertts, Adam G.

2012-01-01

In bacteria, replication is a carefully orchestrated event that unfolds the same way for each bacterium and each cell division. The process of DNA replication in bacteria optimizes cell growth and coordinates high levels of simultaneous replication and transcription. In metazoans, the organization of replication is more enigmatic. The lack of a specific sequence that defines origins of replication has, until recently, severely limited our ability to define the organizing principles of DNA replication. This question is of particular importance as emerging data suggest that replication stress is an important contributor to inherited genetic damage and the genomic instability in tumors. We consider here the replication program in several different organisms including recent genome-wide analyses of replication origins in humans. We review recent studies on the role of cytosine methylation in replication origins, the role of transcriptional looping and gene gating in DNA replication, and the role of chromatin’s 3-dimensional structure in DNA replication. We use these new findings to consider several questions surrounding DNA replication in metazoans: How are origins selected? What is the relationship between replication and transcription? How do checkpoints inhibit origin firing? Why are there early and late firing origins? We then discuss whether oncogenes promote cancer through a role in DNA replication and whether errors in DNA replication are important contributors to the genomic alterations and gene fusion events observed in cancer. We conclude with some important areas for future experimentation. PMID:23634256
Single-molecule FRET studies of the cooperative and non-cooperative binding kinetics of the bacteriophage T4 single-stranded DNA binding protein (gp32) to ssDNA lattices at replication fork junctions

PubMed Central

Lee, Wonbae; Gillies, John P.; Jose, Davis; Israels, Brett A.; von Hippel, Peter H.; Marcus, Andrew H.

2016-01-01

Gene 32 protein (gp32) is the single-stranded (ss) DNA binding protein of the bacteriophage T4. It binds transiently and cooperatively to ssDNA sequences exposed during the DNA replication process and regulates the interactions of the other sub-assemblies of the replication complex during the replication cycle. We here use single-molecule FRET techniques to build on previous thermodynamic studies of gp32 binding to initiate studies of the dynamics of the isolated and cooperative binding of gp32 molecules within the replication complex. DNA primer/template (p/t) constructs are used as models to determine the effects of ssDNA lattice length, gp32 concentration, salt concentration, binding cooperativity and binding polarity at p/t junctions. Hidden Markov models (HMMs) and transition density plots (TDPs) are used to characterize the dynamics of the multi-step assembly pathway of gp32 at p/t junctions of differing polarity, and show that isolated gp32 molecules bind to their ssDNA targets weakly and dissociate quickly, while cooperatively bound dimeric or trimeric clusters of gp32 bind much more tightly, can ‘slide’ on ssDNA sequences, and exhibit binding dynamics that depend on p/t junction polarities. The potential relationships of these binding dynamics to interactions with other components of the T4 DNA replication complex are discussed. PMID:27694621
Reading the tea leaves: Dead transposon copies reveal novel host and transposon biology.

PubMed

McLaughlin, Richard N

2018-03-01

Transposable elements comprise a huge portion of most animal genomes. Unlike many pathogens, these elements leave a mark of their impact via their insertion into host genomes. With proper teasing, these sequences can relay information about the evolutionary history of transposons and their hosts. In a new publication, Larson and colleagues describe a previously unappreciated density of long interspersed element-1 (LINE-1) sequences that have been spliced (LINE-1 and other reverse transcribing elements are necessarily intronless). They provide data to suggest that the retention of these potentially deleterious splice sites in LINE-1 results from the sites' overlap with an important transcription factor binding site. These spliced LINE-1s (i.e., spliced integrated retrotransposed elements [SpiREs]) lose their ability to replicate, suggesting they are evolutionary dead ends. However, the lethality of this splicing could be an efficient means of blocking continued replication of LINE-1. In this way, the record of inactive LINE-1 sequences in the human genome revealed a new, though infrequent, event in the LINE-1 replication cycle and motivates future studies to test whether splicing might be another weapon in the anti-LINE-1 arsenal of host genomes.
Quantifying Selection with Pool-Seq Time Series Data.

PubMed

Taus, Thomas; Futschik, Andreas; Schlötterer, Christian

2017-11-01

Allele frequency time series data constitute a powerful resource for unraveling mechanisms of adaptation, because the temporal dimension captures important information about evolutionary forces. In particular, Evolve and Resequence (E&R), the whole-genome sequencing of replicated experimentally evolving populations, is becoming increasingly popular. Based on computer simulations several studies proposed experimental parameters to optimize the identification of the selection targets. No such recommendations are available for the underlying parameters selection strength and dominance. Here, we introduce a highly accurate method to estimate selection parameters from replicated time series data, which is fast enough to be applied on a genome scale. Using this new method, we evaluate how experimental parameters can be optimized to obtain the most reliable estimates for selection parameters. We show that the effective population size (Ne) and the number of replicates have the largest impact. Because the number of time points and sequencing coverage had only a minor effect, we suggest that time series analysis is feasible without major increase in sequencing costs. We anticipate that time series analysis will become routine in E&R studies. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.
Genome Sequences of Ilzat and Eleri, Two Phages Isolated Using Microbacterium foliorum NRRL B-24224

PubMed Central

Ali, Ilzat; Jones, Acacia Eleri; Mohamed, Aleem

2018-01-01

ABSTRACT Bacteriophages Ilzat and Eleri are newly isolated Siphoviridae infecting Microbacterium foliorum NRRL B-24224. The phage genomes are similar in length, G+C content, and architecture and share 62.9% nucleotide sequence identity. PMID:29650566
Initiation and termination of DNA replication during S phase in relation to cyclins D1, E and A, p21WAF1, Cdt1 and the p12 subunit of DNA polymerase δ revealed in individual cells by cytometry

PubMed Central

Darzynkiewicz, Zbigniew; Zhao, Hong; Zhang, Sufang; Marietta, Y.W.T. Lee; Ernest, Y.C. Lee; Zhang, Zhongtao

2015-01-01

During our recent studies on mechanism of the regulation of human DNA polymerase δ in preparation for DNA replication or repair, multiparameter imaging cytometry as exemplified by laser scanning cytometry (LSC) has been used to assess changes in expression of the following nuclear proteins associated with initiation of DNA replication: cyclin A, PCNA, Ki-67, p21WAF1, DNA replication factor Cdt1 and the smallest subunit of DNA polymerase δ, p12. In the present review, rather than focusing on Pol δ, we emphasize the application of LSC in these studies and outline possibilities offered by the concurrent differential analysis of DNA replication in conjunction with expression of the nuclear proteins. A more extensive analysis of the data on a correlation between rates of EdU incorporation, likely reporting DNA replication, and expression of these proteins, is presently provided. New data, specifically on the expression of cyclin D1 and cyclin E with respect to EdU incorporation as well as on a relationship between expression of cyclin A vs. p21WAF1 and Ki-67 vs. Cdt1, are also reported. Of particular interest is the observation that this approach makes it possible to assess the temporal sequence of degradation of cyclin D1, p21WAF1, Cdt1 and p12, each with respect to initiation of DNA replication and with respect to each other. Also the sequence or reappearance of these proteins in G2 after termination of DNA replication is assessed. The reviewed data provide a more comprehensive presentation of potential markers, whose presence or absence marks the DNA replicating cells. Discussed is also usefulness of these markers as indicators of proliferative activity in cancer tissues that may bear information on tumor progression and have a prognostic value. PMID:26059433
Chromatin Heterogeneity and Distribution of Regulatory Elements in the Late-Replicating Intercalary Heterochromatin Domains of Drosophila melanogaster Chromosomes

PubMed Central

Khoroshko, Varvara A.; Levitsky, Viktor G.; Zykova, Tatyana Yu.; Antonenko, Oksana V.; Belyaeva, Elena S.; Zhimulev, Igor F.

2016-01-01

Late-replicating domains (intercalary heterochromatin) in the Drosophila genome display a number of features suggesting their organization is quite unique. Typically, they are quite large and encompass clusters of functionally unrelated tissue-specific genes. They correspond to the topologically associating domains and conserved microsynteny blocks. Our study aims at exploring further details of molecular organization of intercalary heterochromatin and has uncovered surprising heterogeneity of chromatin composition in these regions. Using the 4HMM model developed in our group earlier, intercalary heterochromatin regions were found to host chromatin fragments with a particular epigenetic profile. Aquamarine chromatin fragments (spanning 0.67% of late-replicating regions) are characterized as a class of sequences that appear heterogeneous in terms of their decompactization. These fragments are enriched with enhancer sequences and binding sites for insulator proteins. They likely mark the chromatin state that is related to the binding of cis-regulatory proteins. Malachite chromatin fragments (11% of late-replicating regions) appear to function as universal transitional regions between two contrasting chromatin states. Namely, they invariably delimit intercalary heterochromatin regions from the adjacent active chromatin of interbands. Malachite fragments also flank aquamarine fragments embedded in the repressed chromatin of late-replicating regions. Significant enrichment of insulator proteins CP190, SU(HW), and MOD2.2 was observed in malachite chromatin. Neither aquamarine nor malachite chromatin types appear to correlate with the positions of highly conserved non-coding elements (HCNE) that are typically replete in intercalary heterochromatin. Malachite chromatin found on the flanks of intercalary heterochromatin regions tends to replicate earlier than the malachite chromatin embedded in intercalary heterochromatin. In other words, there exists a gradient of replication progressing from the flanks of intercalary heterochromatin regions center-wise. The peculiar organization and features of replication in large late-replicating regions are discussed as possible factors shaping the evolutionary stability of intercalary heterochromatin. PMID:27300486
Initiation and termination of DNA replication during S phase in relation to cyclins D1, E and A, p21WAF1, Cdt1 and the p12 subunit of DNA polymerase δ revealed in individual cells by cytometry.

PubMed

Darzynkiewicz, Zbigniew; Zhao, Hong; Zhang, Sufang; Lee, Marietta Y W T; Lee, Ernest Y C; Zhang, Zhongtao

2015-05-20

During our recent studies on mechanism of the regulation of human DNA polymerase δ in preparation for DNA replication or repair, multiparameter imaging cytometry as exemplified by laser scanning cytometry (LSC) has been used to assess changes in expression of the following nuclear proteins associated with initiation of DNA replication: cyclin A, PCNA, Ki-67, p21(WAF1), DNA replication factor Cdt1 and the smallest subunit of DNA polymerase δ, p12. In the present review, rather than focusing on Pol δ, we emphasize the application of LSC in these studies and outline possibilities offered by the concurrent differential analysis of DNA replication in conjunction with expression of the nuclear proteins. A more extensive analysis of the data on a correlation between rates of EdU incorporation, likely reporting DNA replication, and expression of these proteins, is presently provided. New data, specifically on the expression of cyclin D1 and cyclin E with respect to EdU incorporation as well as on a relationship between expression of cyclin A vs. p21(WAF1) and Ki-67 vs. Cdt1, are also reported. Of particular interest is the observation that this approach makes it possible to assess the temporal sequence of degradation of cyclin D1, p21(WAF1), Cdt1 and p12, each with respect to initiation of DNA replication and with respect to each other. Also the sequence or reappearance of these proteins in G2 after termination of DNA replication is assessed. The reviewed data provide a more comprehensive presentation of potential markers, whose presence or absence marks the DNA replicating cells. Discussed is also usefulness of these markers as indicators of proliferative activity in cancer tissues that may bear information on tumor progression and have a prognostic value.
PUTATIVE GENE PROMOTER SEQUENCES IN THE CHLORELLA VIRUSES

PubMed Central

Fitzgerald, Lisa A.; Boucher, Philip T.; Yanai-Balser, Giane; Suhre, Karsten; Graves, Michael V.; Van Etten, James L.

2008-01-01

Three short (7 to 9 nucleotides) highly conserved nucleotide sequences were identified in the putative promoter regions (150 bp upstream and 50 bp downstream of the ATG translation start site) of three members of the genus Chlorovirus, family Phycodnaviridae. Most of these sequences occurred in similar locations within the defined promoter regions. The sequence and location of the motifs were often conserved among homologous ORFs within the Chlorovirus family. One of these conserved sequences (AATGACA) is predominately associated with genes expressed early in virus replication. PMID:18768195
Evaluation and integration of functional annotation pipelines for newly sequenced organisms: the potato genome as a test case.

PubMed

Amar, David; Frades, Itziar; Danek, Agnieszka; Goldberg, Tatyana; Sharma, Sanjeev K; Hedley, Pete E; Proux-Wera, Estelle; Andreasson, Erik; Shamir, Ron; Tzfadia, Oren; Alexandersson, Erik

2014-12-05

For most organisms, even if their genome sequence is available, little functional information about individual genes or proteins exists. Several annotation pipelines have been developed for functional analysis based on sequence, 'omics', and literature data. However, researchers encounter little guidance on how well they perform. Here, we used the recently sequenced potato genome as a case study. The potato genome was selected since its genome is newly sequenced and it is a non-model plant even if there is relatively ample information on individual potato genes, and multiple gene expression profiles are available. We show that the automatic gene annotations of potato have low accuracy when compared to a "gold standard" based on experimentally validated potato genes. Furthermore, we evaluate six state-of-the-art annotation pipelines and show that their predictions are markedly dissimilar (Jaccard similarity coefficient of 0.27 between pipelines on average). To overcome this discrepancy, we introduce a simple GO structure-based algorithm that reconciles the predictions of the different pipelines. We show that the integrated annotation covers more genes, increases by over 50% the number of highly co-expressed GO processes, and obtains much higher agreement with the gold standard. We find that different annotation pipelines produce different results, and show how to integrate them into a unified annotation that is of higher quality than each single pipeline. We offer an improved functional annotation of both PGSC and ITAG potato gene models, as well as tools that can be applied to additional pipelines and improve annotation in other organisms. This will greatly aid future functional analysis of '-omics' datasets from potato and other organisms with newly sequenced genomes. The new potato annotations are available with this paper.
High Diversity of Myocyanophage in Various Aquatic Environments Revealed by High-Throughput Sequencing of Major Capsid Protein Gene With a New Set of Primers.

PubMed

Hou, Weiguo; Wang, Shang; Briggs, Brandon R; Li, Gaoyuan; Xie, Wei; Dong, Hailiang

2018-01-01

Myocyanophages, a group of viruses infecting cyanobacteria, are abundant and play important roles in elemental cycling. Here we investigated the particle-associated viral communities retained on 0.2 μm filters and in sediment samples (representing ancient cyanophage communities) from four ocean and three lake locations, using high-throughput sequencing and a newly designed primer pair targeting a gene fragment (∼145-bp in length) encoding the cyanophage gp23 major capsid protein (MCP). Diverse viral communities were detected in all samples. The fragments of 142-, 145-, and 148-bp in length were most abundant in the amplicons, and most sequences (>92%) belonged to cyanophages. Additionally, different sequencing depths resulted in different diversity estimates of the viral community. Operational taxonomic units obtained from deep sequencing of the MCP gene covered the majority of those obtained from shallow sequencing, suggesting that deep sequencing exhibited a more complete picture of cyanophage community than shallow sequencing. Our results also revealed a wide geographic distribution of marine myocyanophages, i.e., higher dissimilarities of the myocyanophage communities corresponded with the larger distances between the sampling sites. Collectively, this study suggests that the newly designed primer pair can be effectively used to study the community and diversity of myocyanophage from different environments, and the high-throughput sequencing represents a good method to understand viral diversity.
High Diversity of Myocyanophage in Various Aquatic Environments Revealed by High-Throughput Sequencing of Major Capsid Protein Gene With a New Set of Primers

PubMed Central

Hou, Weiguo; Wang, Shang; Briggs, Brandon R.; Li, Gaoyuan; Xie, Wei; Dong, Hailiang

2018-01-01

Myocyanophages, a group of viruses infecting cyanobacteria, are abundant and play important roles in elemental cycling. Here we investigated the particle-associated viral communities retained on 0.2 μm filters and in sediment samples (representing ancient cyanophage communities) from four ocean and three lake locations, using high-throughput sequencing and a newly designed primer pair targeting a gene fragment (∼145-bp in length) encoding the cyanophage gp23 major capsid protein (MCP). Diverse viral communities were detected in all samples. The fragments of 142-, 145-, and 148-bp in length were most abundant in the amplicons, and most sequences (>92%) belonged to cyanophages. Additionally, different sequencing depths resulted in different diversity estimates of the viral community. Operational taxonomic units obtained from deep sequencing of the MCP gene covered the majority of those obtained from shallow sequencing, suggesting that deep sequencing exhibited a more complete picture of cyanophage community than shallow sequencing. Our results also revealed a wide geographic distribution of marine myocyanophages, i.e., higher dissimilarities of the myocyanophage communities corresponded with the larger distances between the sampling sites. Collectively, this study suggests that the newly designed primer pair can be effectively used to study the community and diversity of myocyanophage from different environments, and the high-throughput sequencing represents a good method to understand viral diversity.
Complete Genome Sequences of 38 Gordonia sp. Bacteriophages

PubMed Central

Montgomery, Matthew T.; Bonilla, J. Alfred; Dejong, Randall; Garlena, Rebecca A.; Guerrero Bustamante, Carlos; Klyczek, Karen K.; Russell, Daniel A.; Wertz, John T.; Jacobs-Sera, Deborah; Hatfull, Graham F.

2017-01-01

ABSTRACT We report here the genome sequences of 38 newly isolated bacteriophages using Gordonia terrae 3612 (ATCC 25594) and Gordonia neofelifaecis NRRL59395 as bacterial hosts. All of the phages are double-stranded DNA (dsDNA) tail phages with siphoviral morphologies, with genome sizes ranging from 17,118 bp to 93,843 bp and spanning considerable nucleotide sequence diversity. PMID:28057748

The ASTRAL Compendium in 2004

DOE R&D Accomplishments Database

Chandonia, John-Marc; Hon, Gary; Walker, Nigel S.; Lo Conte, Loredana; Koehl, Patrice; Levitt, Michael; Brenner, Steven E.

2003-09-15

The ASTRAL compendium provides several databases and tools to aid in the analysis of protein structures, particularly through the use of their sequences. Partially derived from the SCOP database of protein structure domains, it includes sequences for each domain and other resources useful for studying these sequences and domain structures. The current release of ASTRAL contains 54,745 domains, more than three times as many as the initial release four years ago. ASTRAL has undergone major transformations in the past two years. In addition to several complete updates each year, ASTRAL is now updated on a weekly basis with preliminary classifications of domains from newly released PDB structures. These classifications are available as a stand-alone database, as well as available integrated into other ASTRAL databases such as representative subsets. To enhance the utility of ASTRAL to structural biologists, all SCOP domains are now made available as PDB-style coordinate files as well as sequences. In addition to sequences and representative subsets based on SCOP domains, sequences and subsets based on PDB chains are newly included in ASTRAL. Several search tools have been added to ASTRAL to facilitate retrieval of data by individual users and automated methods.
Genome-wide analysis of replication timing by next-generation sequencing with E/L Repli-seq.

PubMed

Marchal, Claire; Sasaki, Takayo; Vera, Daniel; Wilson, Korey; Sima, Jiao; Rivera-Mulia, Juan Carlos; Trevilla-García, Claudia; Nogues, Coralin; Nafie, Ebtesam; Gilbert, David M

2018-05-01

This protocol is an extension to: Nat. Protoc. 6, 870-895 (2014); doi:10.1038/nprot.2011.328; published online 02 June 2011Cycling cells duplicate their DNA content during S phase, following a defined program called replication timing (RT). Early- and late-replicating regions differ in terms of mutation rates, transcriptional activity, chromatin marks and subnuclear position. Moreover, RT is regulated during development and is altered in diseases. Here, we describe E/L Repli-seq, an extension of our Repli-chip protocol. E/L Repli-seq is a rapid, robust and relatively inexpensive protocol for analyzing RT by next-generation sequencing (NGS), allowing genome-wide assessment of how cellular processes are linked to RT. Briefly, cells are pulse-labeled with BrdU, and early and late S-phase fractions are sorted by flow cytometry. Labeled nascent DNA is immunoprecipitated from both fractions and sequenced. Data processing leads to a single bedGraph file containing the ratio of nascent DNA from early versus late S-phase fractions. The results are comparable to those of Repli-chip, with the additional benefits of genome-wide sequence information and an increased dynamic range. We also provide computational pipelines for downstream analyses, for parsing phased genomes using single-nucleotide polymorphisms (SNPs) to analyze RT allelic asynchrony, and for direct comparison to Repli-chip data. This protocol can be performed in up to 3 d before sequencing, and requires basic cellular and molecular biology skills, as well as a basic understanding of Unix and R.
A Delicate Balance Between Repair and Replication Factors Regulates Recombination Between Divergent DNA Sequences in Saccharomyces cerevisiae

PubMed Central

Chakraborty, Ujani; George, Carolyn M.; Lyndaker, Amy M.; Alani, Eric

2016-01-01

Single-strand annealing (SSA) is an important homologous recombination mechanism that repairs DNA double strand breaks (DSBs) occurring between closely spaced repeat sequences. During SSA, the DSB is acted upon by exonucleases to reveal complementary sequences that anneal and are then repaired through tail clipping, DNA synthesis, and ligation steps. In baker’s yeast, the Msh DNA mismatch recognition complex and the Sgs1 helicase act to suppress SSA between divergent sequences by binding to mismatches present in heteroduplex DNA intermediates and triggering a DNA unwinding mechanism known as heteroduplex rejection. Using baker’s yeast as a model, we have identified new factors and regulatory steps in heteroduplex rejection during SSA. First we showed that Top3-Rmi1, a topoisomerase complex that interacts with Sgs1, is required for heteroduplex rejection. Second, we found that the replication processivity clamp proliferating cell nuclear antigen (PCNA) is dispensable for heteroduplex rejection, but is important for repairing mismatches formed during SSA. Third, we showed that modest overexpression of Msh6 results in a significant increase in heteroduplex rejection; this increase is due to a compromise in Msh2-Msh3 function required for the clipping of 3′ tails. Thus 3′ tail clipping during SSA is a critical regulatory step in the repair vs. rejection decision; rejection is favored before the 3′ tails are clipped. Unexpectedly, Msh6 overexpression, through interactions with PCNA, disrupted heteroduplex rejection between divergent sequences in another recombination substrate. These observations illustrate the delicate balance that exists between repair and replication factors to optimize genome stability. PMID:26680658
Yellow Fever Virus Exhibits Slower Evolutionary Dynamics than Dengue Virus ▿ †

PubMed Central

Sall, Amadou A.; Faye, Ousmane; Diallo, Mawlouth; Firth, Cadhla; Kitchen, Andrew; Holmes, Edward C.

2010-01-01

Although yellow fever has historically been one of the most important viral infections of humans, relatively little is known about the evolutionary processes that shape its genetic diversity. Similarly, there is limited information on the molecular epidemiology of yellow fever virus (YFV) in Africa even though it most likely first emerged on this continent. Through an analysis of complete E gene sequences, including a newly acquired viral collection from Central and West Africa (Senegal, Cameroon, Central African Republic, Côte d'Ivoire, Mali, and Mauritania), we show that YFV exhibits markedly lower rates of evolutionary change than dengue virus, despite numerous biological similarities between these two viruses. From this observation, along with a lack of clock-like evolutionary behavior in YFV, we suggest that vertical transmission, itself characterized by lower replication rates, may play an important role in the evolution of YFV in its enzootic setting. Despite a reduced rate of nucleotide substitution, phylogenetic patterns and estimates of times to common ancestry in YFV still accord well with the dual histories of colonialism and the slave trade, with areas of sylvatic transmission (such as Kedougou, Senegal) acting as enzootic/epidemic foci. PMID:19889759
In vivo and in vitro infection dynamics of honey bee viruses.

PubMed

Carrillo-Tripp, Jimena; Dolezal, Adam G; Goblirsch, Michael J; Miller, W Allen; Toth, Amy L; Bonning, Bryony C

2016-02-29

The honey bee (Apis mellifera) is commonly infected by multiple viruses. We developed an experimental system for the study of such mixed viral infections in newly emerged honey bees and in the cell line AmE-711, derived from honey bee embryos. When inoculating a mixture of iflavirids [sacbrood bee virus (SBV), deformed wing virus (DWV)] and dicistrovirids [Israeli acute paralysis virus (IAPV), black queen cell virus (BQCV)] in both live bee and cell culture assays, IAPV replicated to higher levels than other viruses despite the fact that SBV was the major component of the inoculum mixture. When a different virus mix composed mainly of the dicistrovirid Kashmir bee virus (KBV) was tested in cell culture, the outcome was a rapid increase in KBV but not IAPV. We also sequenced the complete genome of an isolate of DWV that covertly infects the AmE-711 cell line, and found that this virus does not prevent IAPV and KBV from accumulating to high levels and causing cytopathic effects. These results indicate that different mechanisms of virus-host interaction affect virus dynamics, including complex virus-virus interactions, superinfections, specific virus saturation limits in cells and virus specialization for different cell types.
Deletion of the Clostridium thermocellum recA gene reveals that it is required for thermophilic plasmid replication but not plasmid integration at homologous DNA sequences.

PubMed

Groom, Joseph; Chung, Daehwan; Kim, Sun-Ki; Guss, Adam; Westpheling, Janet

2018-05-28

A limitation to the engineering of cellulolytic thermophiles is the availability of functional, thermostable (≥ 60 °C) replicating plasmid vectors for rapid expression and testing of genes that provide improved or novel fuel molecule production pathways. A series of plasmid vectors for genetic manipulation of the cellulolytic thermophile Caldicellulosiruptor bescii has recently been extended to Clostridium thermocellum, another cellulolytic thermophile that very efficiently solubilizes plant biomass and produces ethanol. While the C. bescii pBAS2 replicon on these plasmids is thermostable, the use of homologous promoters, signal sequences and genes led to undesired integration into the bacterial chromosome, a result also observed with less thermostable replicating vectors. In an attempt to overcome undesired plasmid integration in C. thermocellum, a deletion of recA was constructed. As expected, C. thermocellum ∆recA showed impaired growth in chemically defined medium and an increased susceptibility to UV damage. Interestingly, we also found that recA is required for replication of the C. bescii thermophilic plasmid pBAS2 in C. thermocellum, but it is not required for replication of plasmid pNW33N. In addition, the C. thermocellum recA mutant retained the ability to integrate homologous DNA into the C. thermocellum chromosome. These data indicate that recA can be required for replication of certain plasmids, and that a recA-independent mechanism exists for the integration of homologous DNA into the C. thermocellum chromosome. Understanding thermophilic plasmid replication is not only important for engineering of these cellulolytic thermophiles, but also for developing genetic systems in similar new potentially useful non-model organisms.
Deletion of the Clostridium thermocellum recA Gene Reveals that it is Required for Thermophilic Plasmid Replication but not Plasmid Integration at Homologous DNA Sequences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chung, Daehwan; Groom, Joseph; Kim, Sun-Ki

A limitation to the engineering of cellulolytic thermophiles is the availability of functional, thermostable (>/= 60 degrees C) replicating plasmid vectors for rapid expression and testing of genes that provide improved or novel fuel molecule production pathways. A series of plasmid vectors for genetic manipulation of the cellulolytic thermophile Caldicellulosiruptor bescii has recently been extended to Clostridium thermocellum, another cellulolytic thermophile that very efficiently solubilizes plant biomass and produces ethanol. While the C. bescii pBAS2 replicon on these plasmids is thermostable, the use of homologous promoters, signal sequences and genes led to undesired integration into the bacterial chromosome, a resultmore » also observed with less thermostable replicating vectors. In an attempt to overcome undesired plasmid integration in C. thermocellum, a deletion of recA was constructed. As expected, C. thermocellum ..delta..recA showed impaired growth in chemically defined medium and an increased susceptibility to UV damage. Interestingly, we also found that recA is required for replication of the C. bescii thermophilic plasmid pBAS2 in C. thermocellum, but it is not required for replication of plasmid pNW33N. In addition, the C. thermocellum recA mutant retained the ability to integrate homologous DNA into the C. thermocellum chromosome. These data indicate that recA can be required for replication of certain plasmids, and that a recA-independent mechanism exists for the integration of homologous DNA into the C. thermocellum chromosome. Understanding thermophilic plasmid replication is not only important for engineering of these cellulolytic thermophiles, but also for developing genetic systems in similar new potentially useful non-model organisms.« less
Essential and Dispensable Virus-Encoded Replication Elements Revealed by Efforts To Develop Hypoviruses as Gene Expression Vectors

PubMed Central

Suzuki, Nobuhiro; Geletka, Lynn M.; Nuss, Donald L.

2000-01-01

We have investigated whether hypoviruses, viral agents responsible for virulence attenuation (hypovirulence) of the chestnut blight fungus Cryphonectria parasitica, could serve as gene expression vectors. The infectious cDNA clone of the prototypic hypovirus CHV1-EP713 was modified to generate 20 different vector candidates. Although transient expression was achieved for a subset of vectors that contained the green fluorescent protein gene from Aequorea victoria, long-term expression (past day 8) was not observed for any vector construct. Analysis of viral RNAs recovered from transfected fungal colonies revealed that the foreign genes were readily deleted from the replicating virus, although small portions of foreign sequences were retained by some vectors after months of replication. However, the results of vector viability and progeny characterization provided unexpected new insights into essential and dispensable elements of hypovirus replication. The N-terminal portion (codons 1 to 24) of the 5′-proximal open reading frame (ORF), ORF A, was found to be required for virus replication, while the remaining 598 codons of this ORF were completely dispensable. Substantial alterations were tolerated in the pentanucleotide UAAUG that contains the ORF A termination codon and the overlapping putative initiation codon of the second of the two hypovirus ORFs, ORF B. Replication competence was maintained following either a frameshift mutation that caused a two-codon extension of ORF A or a modification that produced a single-ORF genomic organization. These results are discussed in terms of determinants of hypovirus replication, the potential utility of hypoviruses as gene expression vectors, and possible mechanisms by which hypoviruses recognize and delete foreign sequences. PMID:10906211
Alzheimer's Disease Sequencing Project discovery and replication criteria for cases and controls: Data from a community-based prospective cohort study with autopsy follow-up.

PubMed

Crane, Paul K; Foroud, Tatiana; Montine, Thomas J; Larson, Eric B

2017-12-01

The Alzheimer's Disease Sequencing Project (ADSP) used different criteria for assigning case and control status from the discovery and replication phases of the project. We considered data from a community-based prospective cohort study with autopsy follow-up where participants could be categorized as case, control, or neither by both definitions and compared the two sets of criteria. We used data from the Adult Changes in Thought (ACT) study including Diagnostic and Statistical Manual-IV criteria for dementia status, McKhann et al. criteria for clinical Alzheimer's disease, and Braak and Consortium to Establish a Registry for AD findings on neurofibrillary tangles and neuritic plaques to categorize the 621 ACT participants of European ancestry who died and came to autopsy. We applied ADSP discovery and replication definitions to identify controls, cases, and people who were neither controls nor cases. There was some agreement between the discovery and replication definitions. Major areas of discrepancy included the finding that only 40% of the discovery sample controls had sufficiently low levels of neurofibrillary tangles and neuritic plaques to be considered controls by the replication criteria and the finding that 16% of the replication phase cases were diagnosed with non-AD dementia during life and thus were excluded as cases for the discovery phase. These findings should inform interpretation of genetic association findings from the ADSP. Differences in genetic association findings between the two phases of the study may reflect these different phenotype definitions from the discovery and replication phase of the ADSP. Copyright © 2017 the Alzheimer's Association. Published by Elsevier Inc. All rights reserved.
Identification and Molecular Characterization of the Chloroplast Targeting Domain of Turnip yellow mosaic virus Replication Proteins

PubMed Central

Moriceau, Lucille; Jomat, Lucile; Bressanelli, Stéphane; Alcaide-Loridan, Catherine; Jupin, Isabelle

2017-01-01

Turnip yellow mosaic virus (TYMV) is a positive-strand RNA virus infecting plants. The TYMV 140K replication protein is a key organizer of viral replication complex (VRC) assembly, being responsible for recruitment of the viral polymerase and for targeting the VRCs to the chloroplast envelope where viral replication takes place. However, the structural requirements determining the subcellular localization and membrane association of this essential viral protein have not yet been defined. In this study, we investigated determinants for the in vivo chloroplast targeting of the TYMV 140K replication protein. Subcellular localization studies of deletion mutants identified a 41-residue internal sequence as the chloroplast targeting domain (CTD) of TYMV 140K; this sequence is sufficient to target GFP to the chloroplast envelope. The CTD appears to be located in the C-terminal extension of the methyltransferase domain—a region shared by 140K and its mature cleavage product 98K, which behaves as an integral membrane protein during infection. We predicted the CTD to fold into two amphipathic α-helices—a folding that was confirmed in vitro by circular dichroism spectroscopy analyses of a synthetic peptide. The importance for subcellular localization of the integrity of these amphipathic helices, and the function of 140K/98K, was demonstrated by performing amino acid substitutions that affected chloroplast targeting, membrane association and viral replication. These results establish a short internal α-helical peptide as an unusual signal for targeting proteins to the chloroplast envelope membrane, and provide new insights into membrane targeting of viral replication proteins—a universal feature of positive-strand RNA viruses. PMID:29312393
The Magic Shrinking Machine Revisited: The Presence of Props at Recall Facilitates Memory in 3-Year-Olds

ERIC Educational Resources Information Center

Dahl, Jonna J.; Kingo, Osman S.; Krøjgaard, Peter

2015-01-01

In a seminal study Simcock and Hayne (2002) showed that 3-year-olds were unable to use newly acquired words to describe a "magic" event experienced 6 or 12 months earlier. In the reference study the children's verbal recall was tested without props being present. Inspired by recent evidence, the original design was replicated, testing…
Morphology and Vocabulary Acquisition: Using Visual Cues from Word Parts to Enhance Recall and Decode Newly Encountered Words

ERIC Educational Resources Information Center

Bellomo, Tom

2012-01-01

An enhanced replication of an original quasi-experiment (Tom Bellomo, 2009b) was conducted to quantify the extent of long term retention of word parts and vocabulary. Such were introduced as part of a vocabulary acquisition strategy in a developmental reading course at one southeast four-year college. Aside from incorporating changes to the test…
Chromatin Structure and Replication Origins: Determinants Of Chromosome Replication And Nuclear Organization

PubMed Central

Smith, Owen K.; Aladjem, Mirit I.

2014-01-01

The DNA replication program is, in part, determined by the epigenetic landscape that governs local chromosome architecture and directs chromosome duplication. Replication must coordinate with other biochemical processes occurring concomitantly on chromatin, such as transcription and remodeling, to insure accurate duplication of both genetic and epigenetic features and to preserve genomic stability. The importance of genome architecture and chromatin looping in coordinating cellular processes on chromatin is illustrated by two recent sets of discoveries. First, chromatin-associated proteins that are not part of the core replication machinery were shown to affect the timing of DNA replication. These chromatin-associated proteins could be working in concert, or perhaps in competition, with the transcriptional machinery and with chromatin modifiers to determine the spatial and temporal organization of replication initiation events. Second, epigenetic interactions are mediated by DNA sequences that determine chromosomal replication. In this review we summarize recent findings and current models linking spatial and temporal regulation of the replication program with epigenetic signaling. We discuss these issues in the context of the genome’s three-dimensional structure with an emphasis on events occurring during the initiation of DNA replication. PMID:24905010
Loss of maintenance DNA methylation results in abnormal DNA origin firing during DNA replication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haruta, Mayumi; Shimada, Midori, E-mail: midorism@med.nagoya-cu.ac.jp; Nishiyama, Atsuya

The mammalian maintenance methyltransferase DNMT1 [DNA (cytosine-5-)-methyltransferase 1] mediates the inheritance of the DNA methylation pattern during replication. Previous studies have shown that depletion of DNMT1 causes a severe growth defect and apoptosis in differentiated cells. However, the detailed mechanisms behind this phenomenon remain poorly understood. Here we show that conditional ablation of Dnmt1 in murine embryonic fibroblasts (MEFs) resulted in an aberrant DNA replication program showing an accumulation of late-S phase replication and causing severely defective growth. Furthermore, we found that the catalytic activity and replication focus targeting sequence of DNMT1 are required for a proper DNA replication program.more » Taken together, our findings suggest that the maintenance of DNA methylation by DNMT1 plays a critical role in proper regulation of DNA replication in mammalian cells. - Highlights: • DNMT1 depletion results in an abnormal DNA replication program. • Aberrant DNA replication is independent of the DNA damage checkpoint in DNMT1cKO. • DNMT1 catalytic activity and RFT domain are required for proper DNA replication. • DNMT1 catalytic activity and RFT domain are required for cell proliferation.« less
The effect of Ku on telomere replication time is mediated by telomere length but is independent of histone tail acetylation.

PubMed

Lian, Hui-Yong; Robertson, E Douglas; Hiraga, Shin-ichiro; Alvino, Gina M; Collingwood, David; McCune, Heather J; Sridhar, Akila; Brewer, Bonita J; Raghuraman, M K; Donaldson, Anne D

2011-05-15

DNA replication in Saccharomyces cerevisiae proceeds according to a temporal program. We have investigated the role of the telomere-binding Ku complex in specifying late replication of telomere-proximal sequences. Genome-wide analysis shows that regions extending up to 80 kb from telomeres replicate abnormally early in a yku70 mutant. We find that Ku does not appear to regulate replication time by binding replication origins directly, nor is its effect on telomere replication timing mediated by histone tail acetylation. We show that Ku instead regulates replication timing through its effect on telomere length, because deletion of the telomerase regulator Pif1 largely reverses the short telomere defect of a yku70 mutant and simultaneously rescues its replication timing defect. Consistent with this conclusion, deleting the genome integrity component Elg1 partially rescued both length and replication timing of yku70 telomeres. Telomere length-mediated control of replication timing requires the TG(1-3) repeat-counting component Rif1, because a rif1 mutant replicates telomeric regions early, despite having extended TG(1-3) tracts. Overall, our results suggest that the effect of Ku on telomere replication timing results from its impact on TG(1-3) repeat length and support a model in which Rif1 measures telomere repeat length to ensure that telomere replication timing is correctly programmed.
Overcoming a nucleosomal barrier to replication

PubMed Central

Chang, Han-Wen; Pandey, Manjula; Kulaeva, Olga I.; Patel, Smita S.; Studitsky, Vasily M.

2016-01-01

Efficient overcoming and accurate maintenance of chromatin structure and associated histone marks during DNA replication are essential for normal functioning of the daughter cells. However, the molecular mechanisms of replication through chromatin are unknown. We have studied traversal of uniquely positioned mononucleosomes by T7 replisome in vitro. Nucleosomes present a strong, sequence-dependent barrier for replication, with particularly strong pausing of DNA polymerase at the +(31–40) and +(41–65) regions of the nucleosomal DNA. The exonuclease activity of T7 DNA polymerase increases the overall rate of progression of the replisome through a nucleosome, likely by resolving nonproductive complexes. The presence of nucleosome-free DNA upstream of the replication fork facilitates the progression of DNA polymerase through the nucleosome. After replication, at least 50% of the nucleosomes assume an alternative conformation, maintaining their original positions on the DNA. Our data suggest a previously unpublished mechanism for nucleosome maintenance during replication, likely involving transient formation of an intranucleosomal DNA loop. PMID:27847876
Effects of Data Replication on Data Exfiltration in Mobile Ad Hoc Networks Utilizing Reactive Protocols

DTIC Science & Technology

2015-03-01

2.5.5 Availability Schemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 2.6 Simulation Environments...routing scheme can prove problematic. Two prominent proactive protocols, 7 Destination-Sequenced Distance-Vector (DSDV) and Optimized Link State...distributed file management systems such as Tahoe- LAFS as part of its replication scheme . Altman and De Pellegrini [4] examine the impact of FEC and
Modular structural elements in the replication origin region of Tetrahymena rDNA.

PubMed Central

Du, C; Sanzgiri, R P; Shaiu, W L; Choi, J K; Hou, Z; Benbow, R M; Dobbs, D L

1995-01-01

Computer analyses of the DNA replication origin region in the amplified rRNA genes of Tetrahymena thermophila identified a potential initiation zone in the 5'NTS [Dobbs, Shaiu and Benbow (1994), Nucleic Acids Res. 22, 2479-2489]. This region consists of a putative DNA unwinding element (DUE) aligned with predicted bent DNA segments, nuclear matrix or scaffold associated region (MAR/SAR) consensus sequences, and other common modular sequence elements previously shown to be clustered in eukaryotic chromosomal origin regions. In this study, two mung bean nuclease-hypersensitive sites in super-coiled plasmid DNA were localized within the major DUE-like element predicted by thermodynamic analyses. Three restriction fragments of the 5'NTS region predicted to contain bent DNA segments exhibited anomalous migration characteristic of bent DNA during electrophoresis on polyacrylamide gels. Restriction fragments containing the 5'NTS region bound Tetrahymena nuclear matrices in an in vitro binding assay, consistent with an association of the replication origin region with the nuclear matrix in vivo. The direct demonstration in a protozoan origin region of elements previously identified in Drosophila, chick and mammalian origin regions suggests that clusters of modular structural elements may be a conserved feature of eukaryotic chromosomal origins of replication. Images PMID:7784181
Generation of recombinant European bat lyssavirus type 1 and inter-genotypic compatibility of lyssavirus genotype 1 and 5 antigenome promoters.

PubMed

Orbanz, Jeannette; Finke, Stefan

2010-10-01

Bat lyssaviruses (Fam. Rhabdoviridae) represent a source for the infection of terrestial mammals and the development of rabies disease. Molecular differences in the replication of bat and non-bat lyssaviruses and their contribution to pathogenicity, however, are unknown. One reason for this is the lack of reverse genetics systems for bat-restricted lyssaviruses. To investigate bat lyssavirus replication and host adaptation, we developed a reverse genetics system for European bat lyssavirus type 1 (EBLV-1; genotype 5). This was achieved by co-transfection of HEK-293T cells with a full-length EBLV-1 genome cDNA and expression plasmids for EBLV-1 proteins, resulting in recombinant EBLV-1 (rEBLV-1). Replication of rEBLV-1 was comparable to that of parental virus, showing that rEBLV-1 is a valid tool to investigate EBLV-1 replication functions. In a first approach, we tested whether the terminal promoter sequences of EBLV-1 are genotype-specific. Although genotype 1 (rabies virus) minigenomes were successfully amplified by EBLV-1 helper virus, in the context of the complete virus, only the antigenome promoter (AGP) sequence of EBLV-1 was replaceable, as indicated by comparable replication of rEBLV-1 and the chimeric virus. These analyses demonstrate that the terminal AGPs of genotype 1 and genotype 5 lyssaviruses are compatible with those of the heterologous genotype.
Computational Evaluation of the Strict Master and Random Template Models of Endogenous Retrovirus Evolution

PubMed Central

Nascimento, Fabrícia F.; Rodrigo, Allen G.

2016-01-01

Transposable elements (TEs) are DNA sequences that are able to replicate and move within and between host genomes. Their mechanism of replication is also shared with endogenous retroviruses (ERVs), which are also a type of TE that represent an ancient retroviral infection within animal genomes. Two models have been proposed to explain TE proliferation in host genomes: the strict master model (SMM), and the random template (or transposon) model (TM). In SMM only a single copy of a given TE lineage is able to replicate, and all other genomic copies of TEs are derived from that master copy. In TM, any element of a given family is able to replicate in the host genome. In this paper, we simulated ERV phylogenetic trees under variations of SMM and TM. To test whether current phylogenetic programs can recover the simulated ERV phylogenies, DNA sequence alignments were simulated and maximum likelihood trees were reconstructed and compared to the simulated phylogenies. Results indicate that visual inspection of phylogenetic trees alone can be misleading. However, if a set of statistical summaries is calculated, we are able to distinguish between models with high accuracy by using a data mining algorithm that we introduce here. We also demonstrate the use of our data mining algorithm with empirical data for the porcine endogenous retrovirus (PERV), an ERV that is able to replicate in human and pig cells in vitro. PMID:27649303

The Planning, Implementation, and Movement of an Academic Library Collection.

ERIC Educational Resources Information Center

Kurkul, Donna Lee

1983-01-01

Discusses methodology, logistics, and time/cost study of planning, implementation, and relocation of 682,810 volume Smith College Library collection into its newly constructed and renovated facility. Call number sequence location, collection movement phasing and formulas for sequence distribution, and personnel requirements are noted. Elementary…
Complete Genome Sequences of Four Novel Escherichia coli Bacteriophages Belonging to New Phage Groups

PubMed Central

Kot, Witold

2015-01-01

Here, we describe the sequencing and genome annotations of a set of four Escherichia coli bacteriophages (phages) belonging to newly discovered groups previously consisting of only a single phage and thus expand our knowledge of these phage groups. PMID:26184932
PilY1 Promotes Legionella pneumophila Infection of Human Lung Tissue Explants and Contributes to Bacterial Adhesion, Host Cell Invasion, and Twitching Motility.

PubMed

Hoppe, Julia; Ünal, Can M; Thiem, Stefanie; Grimpe, Louisa; Goldmann, Torsten; Gaßler, Nikolaus; Richter, Matthias; Shevchuk, Olga; Steinert, Michael

2017-01-01

Legionnaires' disease is an acute fibrinopurulent pneumonia. During infection Legionella pneumophila adheres to the alveolar lining and replicates intracellularly within recruited macrophages. Here we provide a sequence and domain composition analysis of the L. pneumophila PilY1 protein, which has a high homology to PilY1 of Pseudomonas aeruginosa . PilY1 proteins of both pathogens contain a von Willebrand factor A (vWFa) and a C-terminal PilY domain. Using cellular fractionation, we assigned the L. pneumophila PilY1 as an outer membrane protein that is only expressed during the transmissive stationary growth phase. PilY1 contributes to infection of human lung tissue explants (HLTEs). A detailed analysis using THP-1 macrophages and A549 lung epithelial cells revealed that this contribution is due to multiple effects depending on host cell type. Deletion of PilY1 resulted in a lower replication rate in THP-1 macrophages but not in A549 cells. Further on, adhesion to THP-1 macrophages and A549 epithelial cells was decreased. Additionally, the invasion into non-phagocytic A549 epithelial cells was drastically reduced when PilY1 was absent. Complementation variants of a PilY1-negative mutant revealed that the C-terminal PilY domain is essential for restoring the wild type phenotype in adhesion, while the putatively mechanosensitive vWFa domain facilitates invasion into non-phagocytic cells. Since PilY1 also promotes twitching motility of L. pneumophila , we discuss the putative contribution of this newly described virulence factor for bacterial dissemination within infected lung tissue.
Resistance of Adenoviral DNA Replication to Aphidicolin Is Dependent on the 72-Kilodalton DNA-Binding Protein

PubMed Central

Foster, David A.; Hantzopoulos, Petros; Zubay, Geoffrey

1982-01-01

Aphidicolin is a highly specific inhibitor of DNA polymerase α and has been most useful for assessing the role of this enzyme in various replication processes (J. A. Huberman, Cell 23:647-648, 1981). Both nuclear DNA replication and simian virus 40 DNA replication are highly sensitive to this drug (Krokan et al., Biochemistry 18:4431-4443, 1979), whereas mitochondrial DNA synthesis is completely insensitive (Zimmerman et al., J. Biol. Chem. 255:11847-11852, 1980). Adenovirus DNA replication is sensitive to aphidicolin, but only at much higher concentrations. These patterns of sensitivity are seen both in vivo and in vitro (Krokan et al., Biochemistry 18:4431-4443, 1979). A temperature-sensitive mutant of adenovirus type 5 known as H5ts125 is able to complete but not initiate new rounds of replication at nonpermissive temperatures (P. C. van der Vliet and J. S. Sussenbach, Virology 67:415-426, 1975). When cells infected with H5ts125 were shifted from permissive (33°C) to nonpermissive (41°C) conditions, the residual DNA synthesis (elongation) showed a striking increase in sensitivity to aphidicolin. The temperature-sensitive mutation of H5ts125 is in the gene for the 72-kilodalton single-stranded DNA-binding protein. This demonstrated that the increased resistance to aphidicolin shown by adenovirus DNA replication was dependent on that protein. It also supports an elongation role for both DNA polymerase α and the 72-kilodalton single-stranded DNA-binding protein in adenovirus DNA replication. Further support for an elongation role of DNA polymerase α came from experiments with permissive temperature conditions and inhibiting levels of aphidicolin in which it was shown that newly initiated strands failed to elongate to completion. Images PMID:6809958
DNA replication origins-where do we begin?

PubMed

Prioleau, Marie-Noëlle; MacAlpine, David M

2016-08-01

For more than three decades, investigators have sought to identify the precise locations where DNA replication initiates in mammalian genomes. The development of molecular and biochemical approaches to identify start sites of DNA replication (origins) based on the presence of defining and characteristic replication intermediates at specific loci led to the identification of only a handful of mammalian replication origins. The limited number of identified origins prevented a comprehensive and exhaustive search for conserved genomic features that were capable of specifying origins of DNA replication. More recently, the adaptation of origin-mapping assays to genome-wide approaches has led to the identification of tens of thousands of replication origins throughout mammalian genomes, providing an unprecedented opportunity to identify both genetic and epigenetic features that define and regulate their distribution and utilization. Here we summarize recent advances in our understanding of how primary sequence, chromatin environment, and nuclear architecture contribute to the dynamic selection and activation of replication origins across diverse cell types and developmental stages. © 2016 Prioleau and MacAlpine; Published by Cold Spring Harbor Laboratory Press.
Aspergillus section Versicolores: nine new species and multilocus DNA sequence based phylogeny

USDA-ARS?s Scientific Manuscript database

ß-tubulin, calmodulin, internal transcribed spacer and partial lsu-rDNA, RNA polymerase, DNA replication licensing factor Mcm7, and pre-rRNA processing protein Tsr1 were amplified and sequenced from 62 A. versicolor clade isolates and analyzed phylogenetically using the concordance model to establis...
Aspergillus section Versicolores, nine new species and multilocus DNA sequence based phylogeny

USDA-ARS?s Scientific Manuscript database

ß-tubulin, calmodulin, internal transcribed spacer and partial lsu-rDNA, RNA polymerase, DNA replication licensing factor Mcm7, and pre-rRNA processing protein Tsr1 were amplified and sequenced from 62 A. versicolor clade isolates and analyzed phylogenetically using the concordance model to establis...
California mild CTV strains that break resistance in Trifoliate Orange

USDA-ARS?s Scientific Manuscript database

This is the final report of a project to characterize California isolates of Citrus tristeza virus (CTV) that replicate in Poncirus trifoliata (trifoliate orange). Next Generation Sequencing (NGS) of viral small interfering RNAs (siRNAs) and assembly of full-length sequences of mild California CTV i...
Application of multi-objective optimization to pooled experiments of next generation sequencing for detection of rare mutations.

PubMed

Zilinskas, Julius; Lančinskas, Algirdas; Guarracino, Mario Rosario

2014-01-01

In this paper we propose some mathematical models to plan a Next Generation Sequencing experiment to detect rare mutations in pools of patients. A mathematical optimization problem is formulated for optimal pooling, with respect to minimization of the experiment cost. Then, two different strategies to replicate patients in pools are proposed, which have the advantage to decrease the overall costs. Finally, a multi-objective optimization formulation is proposed, where the trade-off between the probability to detect a mutation and overall costs is taken into account. The proposed solutions are devised in pursuance of the following advantages: (i) the solution guarantees mutations are detectable in the experimental setting, and (ii) the cost of the NGS experiment and its biological validation using Sanger sequencing is minimized. Simulations show replicating pools can decrease overall experimental cost, thus making pooling an interesting option.
Arthropod phylogenetics in light of three novel millipede (myriapoda: diplopoda) mitochondrial genomes with comments on the appropriateness of mitochondrial genome sequence data for inferring deep level relationships.

PubMed

Brewer, Michael S; Swafford, Lynn; Spruill, Chad L; Bond, Jason E

2013-01-01

Arthropods are the most diverse group of eukaryotic organisms, but their phylogenetic relationships are poorly understood. Herein, we describe three mitochondrial genomes representing orders of millipedes for which complete genomes had not been characterized. Newly sequenced genomes are combined with existing data to characterize the protein coding regions of myriapods and to attempt to reconstruct the evolutionary relationships within the Myriapoda and Arthropoda. The newly sequenced genomes are similar to previously characterized millipede sequences in terms of synteny and length. Unique translocations occurred within the newly sequenced taxa, including one half of the Appalachioria falcifera genome, which is inverted with respect to other millipede genomes. Across myriapods, amino acid conservation levels are highly dependent on the gene region. Additionally, individual loci varied in the level of amino acid conservation. Overall, most gene regions showed low levels of conservation at many sites. Attempts to reconstruct the evolutionary relationships suffered from questionable relationships and low support values. Analyses of phylogenetic informativeness show the lack of signal deep in the trees (i.e., genes evolve too quickly). As a result, the myriapod tree resembles previously published results but lacks convincing support, and, within the arthropod tree, well established groups were recovered as polyphyletic. The novel genome sequences described herein provide useful genomic information concerning millipede groups that had not been investigated. Taken together with existing sequences, the variety of compositions and evolution of myriapod mitochondrial genomes are shown to be more complex than previously thought. Unfortunately, the use of mitochondrial protein-coding regions in deep arthropod phylogenetics appears problematic, a result consistent with previously published studies. Lack of phylogenetic signal renders the resulting tree topologies as suspect. As such, these data are likely inappropriate for investigating such ancient relationships.
Synchronous scan-projection lithography on overall circumference of fine pipes with a diameter of 2 mm

NASA Astrophysics Data System (ADS)

Horiuchi, Toshiyuki; Furuhata, Takahiro; Muro, Hideyuki

2016-06-01

The scan-projection exposure of small-diameter pipe surfaces was investigated using a newly developed prototype exposure system. It is necessary to secure a very large depth of focus for printing thick resist patterns on round pipe surfaces with a roughness larger than that of semiconductor wafers. For this reason, a camera lens with a low numerical aperture of 0.089 was used as a projection lens, and the momentary exposure area was limited by a narrow slit with a width of 800 µm. Thus, patterns on a flat reticle were replicated on a pipe surface by linearly moving the reticle and rotating the pipe synchronously. By using a reticle with inclined line-and-space patterns, helical patterns with a width of 30 µm were successfully replicated on stainless-steel pipes with an outer diameter of 2 mm and coated with a 10-µm-thick negative resist. The patterns replicated at the start and stop edges were smoothly stitched seamlessly.
Replication of alpha-satellite DNA arrays in endogenous human centromeric regions and in human artificial chromosome

PubMed Central

Erliandri, Indri; Fu, Haiqing; Nakano, Megumi; Kim, Jung-Hyun; Miga, Karen H.; Liskovykh, Mikhail; Earnshaw, William C.; Masumoto, Hiroshi; Kouprina, Natalay; Aladjem, Mirit I.; Larionov, Vladimir

2014-01-01

In human chromosomes, centromeric regions comprise megabase-size arrays of 171 bp alpha-satellite DNA monomers. The large distances spanned by these arrays preclude their replication from external sites and imply that the repetitive monomers contain replication origins. However, replication within these arrays has not previously been profiled and the role of alpha-satellite DNA in initiation of DNA replication has not yet been demonstrated. Here, replication of alpha-satellite DNA in endogenous human centromeric regions and in de novo formed Human Artificial Chromosome (HAC) was analyzed. We showed that alpha-satellite monomers could function as origins of DNA replication and that replication of alphoid arrays organized into centrochromatin occurred earlier than those organized into heterochromatin. The distribution of inter-origin distances within centromeric alphoid arrays was comparable to the distribution of inter-origin distances on randomly selected non-centromeric chromosomal regions. Depletion of CENP-B, a kinetochore protein that binds directly to a 17 bp CENP-B box motif common to alpha-satellite DNA, resulted in enrichment of alpha-satellite sequences for proteins of the ORC complex, suggesting that CENP-B may have a role in regulating the replication of centromeric regions. Mapping of replication initiation sites in the HAC revealed that replication preferentially initiated in transcriptionally active regions. PMID:25228468
Intersubtype Differences in the Effect of a Rare p24 Gag Mutation on HIV-1 Replicative Fitness

PubMed Central

Chopera, Denis R.; Cotton, Laura A.; Zawaira, Alexander; Mann, Jaclyn K.; Ngandu, Nobubelo K.; Ntale, Roman; Carlson, Jonathan M.; Mlisana, Koleka; Woodman, Zenda; de Assis Rosa, Debra; Martin, Eric; Miura, Toshiyuki; Pereyra, Florencia; Walker, Bruce D.; Gray, Clive M.; Martin, Darren P.; Ndung'u, Thumbi; Brockman, Mark A.; Karim, Salim Abdool

2012-01-01

Certain immune-driven mutations in HIV-1, such as those arising in p24Gag, decrease viral replicative capacity. However, the intersubtype differences in the replicative consequences of such mutations have not been explored. In HIV-1 subtype B, the p24Gag M250I mutation is a rare variant (0.6%) that is enriched among elite controllers (7.2%) (P = 0.0005) and appears to be a rare escape variant selected by HLA-B58 supertype alleles (P < 0.01). In contrast, in subtype C, it is a relatively common minor polymorphic variant (10 to 15%) whose appearance is not associated with a particular HLA allele. Using site-directed mutant viruses, we demonstrate that M250I reduces in vitro viral replicative capacity in both subtype B and subtype C sequences. However, whereas in subtype C downstream compensatory mutations at p24Gag codons 252 and 260 reduce the adverse effects of M250I, fitness costs in subtype B appear difficult to restore. Indeed, patient-derived subtype B sequences harboring M250I exhibited in vitro replicative defects, while those from subtype C did not. The structural implications of M250I were predicted by protein modeling to be greater in subtype B versus C, providing a potential explanation for its lower frequency and enhanced replicative defects in subtype B. In addition to accounting for genetic differences between HIV-1 subtypes, the design of cytotoxic-T-lymphocyte-based vaccines may need to account for differential effects of host-driven viral evolution on viral fitness. PMID:23015721
A free VP3 C-terminus is essential for the replication of infectious bursal disease virus.

PubMed

Mosley, Yung-Yi C; Wu, Ching Ching; Lin, Tsang Long

2017-03-15

Green fluorescent protein (GFP) has been successfully incorporated into the viral-like particles of infectious bursal disease virus (IBDV) with a linker at the C-terminus of VP3 in a baculovirus system. However, when the same locus in segment A was used to express GFP by a reverse genetic (RG) system, no viable GFP-expressing IBDV was recovered. To elucidate the underlying mechanism, cDNA construct of segment A with only the linker sequence (9 amino acids) was applied to generate RG IBDV virus (rIBDV). Similarly, no rIBDV was recovered. Moreover, when the incubation after transfection was extended, wildtype rIBDV without the linker was recovered suggesting a free C-terminus of VP3 might be necessary for IBDV replication. On the other hand, rIBDV could be recovered when additional sequence (up to 40 nucleotides) were inserted at the 3' noncoding region (NCR) adjacent to the stop codon of VP3, suggesting that the burden of the linker sequence was not in the stretched genome size but the disruption of the VP3 function. Finally, when the stop codon of VP3 was deleted in segment A to extend the translation into the 3' NCR without introducing additional genomic sequence, no rIBDV was recovered. Our data suggest that a free VP3 C-terminus is essential for IBDV replication. Copyright © 2017 Elsevier B.V. All rights reserved.
West Nile virus (WNV) genome RNAs with up to three adjacent mutations that disrupt long distance 5'-3' cyclization sequence basepairs are viable

DOE Office of Scientific and Technical Information (OSTI.GOV)

Basu, Mausumi; Brinton, Margo A., E-mail: mbrinton@gsu.ed

2011-03-30

Mosquito-borne flavivirus genomes contain conserved 5' and 3' cyclization sequences (CYC) that facilitate long distance RNA-RNA interactions. In previous studies, flavivirus replicon RNA replication was completely inhibited by single or multiple mismatching CYC nt substitutions. In the present study, full-length WNV genomes with one, two or three mismatching CYC substitutions showed reduced replication efficiencies but were viable and generated revertants with increased replication efficiency. Several different three adjacent mismatching CYC substitution mutant RNAs were rescued by a second site mutation that created an additional basepair (nts 147-10913) on the internal genomic side of the 5'-3' CYC. The finding that full-lengthmore » genomes with up to three mismatching CYC mutations are viable and can be rescued by a single nt spontaneous mutation indicates that more than three adjacent CYC basepair substitutions would be required to increase the safety of vaccine genomes by creating mismatches in inter-genomic recombinants.« less
Mechanism for Coordinated RNA Packaging and Genome Replication by Rotavirus Polymerase VP1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Xiaohui; McDonald, Sarah M.; Tortorici, M. Alejandra

2009-04-08

Rotavirus RNA-dependent RNA polymerase VP1 catalyzes RNA synthesis within a subviral particle. This activity depends on core shell protein VP2. A conserved sequence at the 3' end of plus-strand RNA templates is important for polymerase association and genome replication. We have determined the structure of VP1 at 2.9 {angstrom} resolution, as apoenzyme and in complex with RNA. The cage-like enzyme is similar to reovirus {lambda}3, with four tunnels leading to or from a central, catalytic cavity. A distinguishing characteristic of VP1 is specific recognition, by conserved features of the template-entry channel, of four bases, UGUG, in the conserved 3' sequence.more » Well-defined interactions with these bases position the RNA so that its 3' end overshoots the initiating register, producing a stable but catalytically inactive complex. We propose that specific 3' end recognition selects rotavirus RNA for packaging and that VP2 activates the autoinhibited VP1/RNA complex to coordinate packaging and genome replication.« less
Msh2-Msh3 Interferes with Okazaki Fragment Processing to Promote Trinucleotide Repeat Expansions

PubMed Central

Kantartzis, Athena; Williams, Gregory M.; Balakrishnan, Lata; Roberts, Rick L.; Surtees, Jennifer A.; Bambara, Robert A.

2012-01-01

Summary Trinucleotide repeat (TNR) expansions are the underlying cause of more than forty neurodegenerative and neuromuscular diseases, including myotonic dystrophy and Huntington’s disease. Although genetic evidence has attributed the cause of these diseases to errors in DNA replication and/or repair, clear molecular mechanisms have not been described. We have focused on the role of the mismatch repair complex Msh2-Msh3 in promoting TNR expansions. We demonstrate that Msh2-Msh3 promotes CTG and CAG repeat expansions in vivo in Saccharomyces cerevisiae. We further provide biochemical evidence that Msh2-Msh3 directly interferes with normal Okazaki fragment processing by flap endonuclease1 (Rad27) and DNA Ligase I (Cdc9) in the presence of TNR sequences, thereby producing small, incremental expansion events. We believe that this is the first mechanistic evidence showing the interplay of replication and repair proteins in the expansion of sequences during lagging strand DNA replication. PMID:22938864
Msh2-Msh3 interferes with Okazaki fragment processing to promote trinucleotide repeat expansions.

PubMed

Kantartzis, Athena; Williams, Gregory M; Balakrishnan, Lata; Roberts, Rick L; Surtees, Jennifer A; Bambara, Robert A

2012-08-30

Trinucleotide repeat (TNR) expansions are the underlying cause of more than 40 neurodegenerative and neuromuscular diseases, including myotonic dystrophy and Huntington's disease. Although genetic evidence points to errors in DNA replication and/or repair as the cause of these diseases, clear molecular mechanisms have not been described. Here, we focused on the role of the mismatch repair complex Msh2-Msh3 in promoting TNR expansions. We demonstrate that Msh2-Msh3 promotes CTG and CAG repeat expansions in vivo in Saccharomyces cerevisiae. Furthermore, we provide biochemical evidence that Msh2-Msh3 directly interferes with normal Okazaki fragment processing by flap endonuclease1 (Rad27) and DNA ligase I (Cdc9) in the presence of TNR sequences, thereby producing small, incremental expansion events. We believe that this is the first mechanistic evidence showing the interplay of replication and repair proteins in the expansion of sequences during lagging-strand DNA replication. Copyright © 2012 The Authors. Published by Elsevier Inc. All rights reserved.
The bovine lactation genome: Insights into the evolution of mammalian milk

USDA-ARS?s Scientific Manuscript database

The newly assembled Bos Taurus genome sequence enables the linkage of bovine milk and lactation data with other mammalian genomes. Using publicly available milk proteome data and mammary expressed sequence tags, 197 milk protein genes and over 6,000 mammary genes were identified in the bovine genome...
Draft genome sequences of four parasaccharibacter apium strains isolated from honey bees

USDA-ARS?s Scientific Manuscript database

Parasaccharibacter apium is a newly described bacterium of honey bees that exhibits multiple ecological strategies in their host, from beneficial to pathogenic. Using niche-specific 16S rRNA gene sequences and bacterial genomes, we describe the ecology of this bacterium and its relationship to other...

Draft Genome Sequence of Enterococcus faecium Strain J19, Isolated from Cabbage

PubMed Central

2018-01-01

ABSTRACT Herein, we report the draft genome sequence of a newly discovered probiotic strain, Enterococcus faecium J19, which was isolated from cabbage. Strain J19 has shown antagonistic effects against the human foodborne pathogen Listeria monocytogenes in coculture and in different food matrices. PMID:29622613
Design of experiments on 135 cloned poplar trees to map environmental influence in greenhouse.

PubMed

Pinto, Rui Climaco; Stenlund, Hans; Hertzberg, Magnus; Lundstedt, Torbjörn; Johansson, Erik; Trygg, Johan

2011-01-31

To find and ascertain phenotypic differences, minimal variation between biological replicates is always desired. Variation between the replicates can originate from genetic transformation but also from environmental effects in the greenhouse. Design of experiments (DoE) has been used in field trials for many years and proven its value but is underused within functional genomics including greenhouse experiments. We propose a strategy to estimate the effect of environmental factors with the ultimate goal of minimizing variation between biological replicates, based on DoE. DoE can be analyzed in many ways. We present a graphical solution together with solutions based on classical statistics as well as the newly developed OPLS methodology. In this study, we used DoE to evaluate the influence of plant specific factors (plant size, shoot type, plant quality, and amount of fertilizer) and rotation of plant positions on height and section area of 135 cloned wild type poplar trees grown in the greenhouse. Statistical analysis revealed that plant position was the main contributor to variability among biological replicates and applying a plant rotation scheme could reduce this variation. Copyright © 2010 Elsevier B.V. All rights reserved.
Early intranuclear replication of African swine fever virus genome modifies the landscape of the host cell nucleus.

PubMed

Simões, Margarida; Martins, Carlos; Ferreira, Fernando

2015-12-02

Although African swine fever virus (ASFV) replicates in viral cytoplasmic factories, the presence of viral DNA within the host cell nucleus has been previously reported to be essential for productive infection. Herein, we described, for the first time, the intranuclear distribution patterns of viral DNA replication events, preceding those that occur in the cytoplasmic compartment. Using BrdU pulse-labelling experiments, newly synthesized ASFV genomes were exclusively detected inside the host cell nucleus at the early phase of infection, both in swine monocyte-derived macrophages (MDMs) and Vero cells. From 8hpi onwards, BrdU labelling was only observed in ASFV cytoplasmic factories. Our results also show that ASFV specifically activates the Ataxia Telangiectasia Mutated Rad-3 related (ATR) pathway in ASFV-infected swine MDMs from the early phase of infection, most probably because ASFV genome is recognized as foreign DNA. Morphological changes of promyelocytic leukaemia nuclear bodies (PML-NBs), nuclear speckles and Cajal bodies were also found in ASFV-infected swine MDMs, strongly suggesting the viral modulation of cellular antiviral responses and cellular transcription, respectively. As described for other viral infections, the nuclear reorganization that takes place during ASFV infection may also provide an environment that favours its intranuclear replication events. Altogether, our results contribute for a better understanding of ASFV replication strategies, starting with an essential intranuclear DNA replication phase which induces host nucleus changes towards a successful viral infection. Copyright © 2015 Elsevier B.V. All rights reserved.
Noumeavirus replication relies on a transient remote control of the host nucleus

PubMed Central

Fabre, Elisabeth; Jeudy, Sandra; Santini, Sébastien; Legendre, Matthieu; Trauchessec, Mathieu; Couté, Yohann; Claverie, Jean-Michel; Abergel, Chantal

2017-01-01

Acanthamoeba are infected by a remarkable diversity of large dsDNA viruses, the infectious cycles of which have been characterized using genomics, transcriptomics and electron microscopy. Given their gene content and the persistence of the host nucleus throughout their infectious cycle, the Marseilleviridae were initially assumed to fully replicate in the cytoplasm. Unexpectedly, we find that their virions do not incorporate the virus-encoded transcription machinery, making their replication nucleus-dependent. However, instead of delivering their DNA to the nucleus, the Marseilleviridae initiate their replication by transiently recruiting the nuclear transcription machinery to their cytoplasmic viral factory. The nucleus recovers its integrity after becoming leaky at an early stage. This work highlights the importance of virion proteomic analyses to complement genome sequencing in the elucidation of the replication scheme and evolution of large dsDNA viruses. PMID:28429720
Repliscan: a tool for classifying replication timing regions.

PubMed

Zynda, Gregory J; Song, Jawon; Concia, Lorenzo; Wear, Emily E; Hanley-Bowdoin, Linda; Thompson, William F; Vaughn, Matthew W

2017-08-07

Replication timing experiments that use label incorporation and high throughput sequencing produce peaked data similar to ChIP-Seq experiments. However, the differences in experimental design, coverage density, and possible results make traditional ChIP-Seq analysis methods inappropriate for use with replication timing. To accurately detect and classify regions of replication across the genome, we present Repliscan. Repliscan robustly normalizes, automatically removes outlying and uninformative data points, and classifies Repli-seq signals into discrete combinations of replication signatures. The quality control steps and self-fitting methods make Repliscan generally applicable and more robust than previous methods that classify regions based on thresholds. Repliscan is simple and effective to use on organisms with different genome sizes. Even with analysis window sizes as small as 1 kilobase, reliable profiles can be generated with as little as 2.4x coverage.
Transposition-mediated DNA re-replication in maize

PubMed Central

Zhang, Jianbo; Zuo, Tao; Wang, Dafang; Peterson, Thomas

2014-01-01

Every DNA segment in a eukaryotic genome normally replicates once and only once per cell cycle to maintain genome stability. We show here that this restriction can be bypassed through alternative transposition, a transposition reaction that utilizes the termini of two separate, nearby transposable elements (TEs). Our results suggest that alternative transposition during S phase can induce re-replication of the TEs and their flanking sequences. The DNA re-replication can spontaneously abort to generate double-strand breaks, which can be repaired to generate Composite Insertions composed of transposon termini flanking segmental duplications of various lengths. These results show how alternative transposition coupled with DNA replication and repair can significantly alter genome structure and may have contributed to rapid genome evolution in maize and possibly other eukaryotes. DOI: http://dx.doi.org/10.7554/eLife.03724.001 PMID:25406063
The replication domain model: regulating replicon firing in the context of large-scale chromosome architecture.

PubMed

Pope, Benjamin D; Gilbert, David M

2013-11-29

The "Replicon Theory" of Jacob, Brenner, and Cuzin has reliably served as the paradigm for regulating the sites where individual replicons initiate replication. Concurrent with the replicon model was Taylor's demonstration that plant and animal chromosomes replicate segmentally in a defined temporal sequence, via cytologically defined units too large to be accounted for by a single replicon. Instead, there seemed to be a program to choreograph when chromosome units replicate during S phase, executed by initiation at clusters of individual replicons within each segment. Here, we summarize recent molecular evidence for the existence of such units, now known as "replication domains", and discuss how the organization of large chromosomes into structural units has added additional layers of regulation to the original replicon model. Copyright © 2012 Elsevier Ltd. All rights reserved.
A Molecular Sensor To Characterize Arenavirus Envelope Glycoprotein Cleavage by Subtilisin Kexin Isozyme 1/Site 1 Protease.

PubMed

Oppliger, Joel; da Palma, Joel Ramos; Burri, Dominique J; Bergeron, Eric; Khatib, Abdel-Majid; Spiropoulou, Christina F; Pasquato, Antonella; Kunz, Stefan

2016-01-15

Arenaviruses are emerging viruses including several causative agents of severe hemorrhagic fevers in humans. The advent of next-generation sequencing technology has greatly accelerated the discovery of novel arenavirus species. However, for many of these viruses, only genetic information is available, and their zoonotic disease potential remains unknown. During the arenavirus life cycle, processing of the viral envelope glycoprotein precursor (GPC) by the cellular subtilisin kexin isozyme 1 (SKI-1)/site 1 protease (S1P) is crucial for productive infection. The ability of newly emerging arenaviruses to hijack human SKI-1/S1P appears, therefore, to be a requirement for efficient zoonotic transmission and human disease potential. Here we implement a newly developed cell-based molecular sensor for SKI-1/S1P to characterize the processing of arenavirus GPC-derived target sequences by human SKI-1/S1P in a quantitative manner. We show that only nine amino acids flanking the putative cleavage site are necessary and sufficient to accurately recapitulate the efficiency and subcellular location of arenavirus GPC processing. In a proof of concept, our sensor correctly predicts efficient processing of the GPC of the newly emergent pathogenic Lujo virus by human SKI-1/S1P and defines the exact cleavage site. Lastly, we employed our sensor to show efficient GPC processing of a panel of pathogenic and nonpathogenic New World arenaviruses, suggesting that GPC cleavage represents no barrier for zoonotic transmission of these pathogens. Our SKI-1/S1P sensor thus represents a rapid and robust test system for assessment of the processing of putative cleavage sites derived from the GPCs of newly discovered arenavirus by the SKI-1/S1P of humans or any other species, based solely on sequence information. Arenaviruses are important emerging human pathogens that can cause severe hemorrhagic fevers with high mortality in humans. A crucial step in productive arenavirus infection of human cells is the processing of the viral envelope glycoprotein by the cellular subtilisin kexin isozyme 1 (SKI-1)/site 1 protease (S1P). In order to break the species barrier during zoonotic transmission and cause severe disease in humans, newly emerging arenaviruses must be able to hijack human SKI-1/S1P efficiently. Here we implement a newly developed cell-based molecular sensor for human SKI-1/S1P to characterize the processing of arenavirus glycoproteins in a quantitative manner. We further use our sensor to correctly predict efficient processing of the glycoprotein of the newly emergent pathogenic Lujo virus by human SKI-1/S1P. Our sensor thus represents a rapid and robust test system with which to assess whether the glycoprotein of any newly emerging arenavirus can be efficiently processed by human SKI-1/S1P, based solely on sequence information. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
Single-Molecule Sequencing Reveals Complex Genome Variation of Hepatitis B Virus during 15 Years of Chronic Infection following Liver Transplantation

PubMed Central

Betz-Stablein, B. D.; Töpfer, A.; Littlejohn, M.; Yuen, L.; Colledge, D.; Sozzi, V.; Angus, P.; Thompson, A.; Revill, P.; Beerenwinkel, N.; Warner, N.

2016-01-01

ABSTRACT Chronic hepatitis B (CHB) is prevalent worldwide. The infectious agent, hepatitis B virus (HBV), replicates via an RNA intermediate and is error prone, leading to the rapid generation of closely related but not identical viral variants, including those that can escape host immune responses and antiviral treatments. The complexity of CHB can be further enhanced by the presence of HBV variants with large deletions in the genome generated via splicing (spHBV variants). Although spHBV variants are incapable of autonomous replication, their replication is rescued by wild-type HBV. spHBV variants have been shown to enhance wild-type virus replication, and their prevalence increases with liver disease progression. Single-molecule deep sequencing was performed on whole HBV genomes extracted from samples, including the liver explant, longitudinally collected from a subject with CHB over a 15-year period after liver transplantation. By employing novel bioinformatics methods, this analysis showed that the dynamics of the viral population across a period of changing treatment regimens was complex. The spHBV variants detected in the liver explant remained present posttransplantation, and a highly diverse novel spHBV population as well as variants with multiple deletions in the pre-S genes emerged. The identification of novel mutations outside the HBV reverse transcriptase gene that co-occurred with known drug resistance-associated mutations highlights the relevance of using full-genome deep sequencing and supports the hypothesis that drug resistance involves interactions across the full length of the HBV genome. IMPORTANCE Single-molecule sequencing allowed the characterization, in unprecedented detail, of the evolution of HBV populations and offered unique insights into the dynamics of defective and spHBV variants following liver transplantation and complex treatment regimens. This analysis also showed the rapid adaptation of HBV populations to treatment regimens with evolving drug resistance phenotypes and evidence of purifying selection across the whole genome. Finally, the new open-source bioinformatics tools with the capacity to easily identify potential spliced variants from deep sequencing data are freely available. PMID:27252524
Optimization and quality control of genome-wide Hi-C library preparation.

PubMed

Zhang, Xiang-Yuan; He, Chao; Ye, Bing-Yu; Xie, De-Jian; Shi, Ming-Lei; Zhang, Yan; Shen, Wen-Long; Li, Ping; Zhao, Zhi-Hu

2017-09-20

Highest-throughput chromosome conformation capture (Hi-C) is one of the key assays for genome- wide chromatin interaction studies. It is a time-consuming process that involves many steps and many different kinds of reagents, consumables, and equipments. At present, the reproducibility is unsatisfactory. By optimizing the key steps of the Hi-C experiment, such as crosslinking, pretreatment of digestion, inactivation of restriction enzyme, and in situ ligation etc., we established a robust Hi-C procedure and prepared two biological replicates of Hi-C libraries from the GM12878 cells. After preliminary quality control by Sanger sequencing, the two replicates were high-throughput sequenced. The bioinformatics analysis of the raw sequencing data revealed the mapping-ability and pair-mate rate of the raw data were around 90% and 72%, respectively. Additionally, after removal of self-circular ligations and dangling-end products, more than 96% of the valid pairs were reached. Genome-wide interactome profiling shows clear topological associated domains (TADs), which is consistent with previous reports. Further correlation analysis showed that the two biological replicates strongly correlate with each other in terms of both bin coverage and all bin pairs. All these results indicated that the optimized Hi-C procedure is robust and stable, which will be very helpful for the wide applications of the Hi-C assay.
Chromosome evolution in the Thermotogales: large-scale inversions and strain diversification of CRISPR sequences.

PubMed

DeBoy, Robert T; Mongodin, Emmanuel F; Emerson, Joanne B; Nelson, Karen E

2006-04-01

In the present study, the chromosomes of two members of the Thermotogales were compared. A whole-genome alignment of Thermotoga maritima MSB8 and Thermotoga neapolitana NS-E has revealed numerous large-scale DNA rearrangements, most of which are associated with CRISPR DNA repeats and/or tRNA genes. These DNA rearrangements do not include the putative origin of DNA replication but move within the same replichore, i.e., the same replicating half of the chromosome (delimited by the replication origin and terminus). Based on cumulative GC skew analysis, both the T. maritima and T. neapolitana lineages contain one or two major inverted DNA segments. Also, based on PCR amplification and sequence analysis of the DNA joints that are associated with the major rearrangements, the overall chromosome architecture was found to be conserved at most DNA joints for other strains of T. neapolitana. Taken together, the results from this analysis suggest that the observed chromosomal rearrangements in the Thermotogales likely occurred by successive inversions after their divergence from a common ancestor and before strain diversification. Finally, sequence analysis shows that size polymorphisms in the DNA joints associated with CRISPRs can be explained by expansion and possibly contraction of the DNA repeat and spacer unit, providing a tool for discerning the relatedness of strains from different geographic locations.
Rapid Multi-Locus Sequence Typing Using Microfluidic Biochips

DTIC Science & Technology

2010-05-12

Sequence Types. The evolutionary history of all the B. cereus MLST concatenated Sequence Types (545 taxa, 2,394 nucleotide positions) was inferred using...the Neighbor-Joining method [28]. The bootstrap consensus tree inferred from 100 replicates was taken to represent the evolutionary history of the... Chlamydia (manuscript in preparation) and performed pilot studies on Staphylococcus aureus and Streptoccus pneumoniae (Data S4 and Text S2). Another potential
Selection of homeotic proteins for binding to a human DNA replication origin.

PubMed

de Stanchina, E; Gabellini, D; Norio, P; Giacca, M; Peverali, F A; Riva, S; Falaschi, A; Biamonti, G

2000-06-09

We have previously shown that a cell cycle-dependent nucleoprotein complex assembles in vivo on a 74 bp sequence within the human DNA replication origin associated to the Lamin B2 gene. Here, we report the identification, using a one-hybrid screen in yeast, of three proteins interacting with the 74 bp sequence. All of them, namely HOXA13, HOXC10 and HOXC13, are orthologues of the Abdominal-B gene of Drosophila melanogaster and are members of the homeogene family of developmental regulators. We describe the complete open reading frame sequence of HOXC10 and HOXC13 along with the structure of the HoxC13 gene. The specificity of binding of these two proteins to the Lamin B2 origin is confirmed by both band-shift and in vitro footprinting assays. In addition, the ability of HOXC10 and HOXC13 to increase the activity of a promoter containing the 74 bp sequence, as assayed by CAT-assay experiments, demonstrates a direct interaction of these homeoproteins with the origin sequence in mammalian cells. We also show that HOXC10 expression is cell-type-dependent and positively correlates with cell proliferation. Copyright 2000 Academic Press.
Continuous in vitro evolution of bacteriophage RNA polymerase promoters

NASA Technical Reports Server (NTRS)

Breaker, R. R.; Banerji, A.; Joyce, G. F.

1994-01-01

Rapid in vitro evolution of bacteriophage T7, T3, and SP6 RNA polymerase promoters was achieved by a method that allows continuous enrichment of DNAs that contain functional promoter elements. This method exploits the ability of a special class of nucleic acid molecules to replicate continuously in the presence of both a reverse transcriptase and a DNA-dependent RNA polymerase. Replication involves the synthesis of both RNA and cDNA intermediates. The cDNA strand contains an embedded promoter sequence, which becomes converted to a functional double-stranded promoter element, leading to the production of RNA transcripts. Synthetic cDNAs, including those that contain randomized promoter sequences, can be used to initiate the amplification cycle. However, only those cDNAs that contain functional promoter sequences are able to produce RNA transcripts. Furthermore, each RNA transcript encodes the RNA polymerase promoter sequence that was responsible for initiation of its own transcription. Thus, the population of amplifying molecules quickly becomes enriched for those templates that encode functional promoters. Optimal promoter sequences for phage T7, T3, and SP6 RNA polymerase were identified after a 2-h amplification reaction, initiated in each case with a pool of synthetic cDNAs encoding greater than 10(10) promoter sequence variants.
Molecular characterisation of Atlantic salmon paramyxovirus (ASPV): A novel paramyxovirus associated with proliferative gill inflammation

USGS Publications Warehouse

Falk, K.; Batts, W.N.; Kvellestad, A.; Kurath, G.; Wiik-Nielsen, J.; Winton, J.R.

2008-01-01

Atlantic salmon paramyxovirus (ASPV) was isolated in 1995 from gills of farmed Atlantic salmon suffering from proliferative gill inflammation. The complete genome sequence of ASPV was determined, revealing a genome 16,968 nucleotides in length consisting of six non-overlapping genes coding for the nucleo- (N), phospho- (P), matrix- (M), fusion- (F), haemagglutinin-neuraminidase- (HN) and large polymerase (L) proteins in the order 3???-N-P-M-F-HN-L-5???. The various conserved features related to virus replication found in most paramyxoviruses were also found in ASPV. These include: conserved and complementary leader and trailer sequences, tri-nucleotide intergenic regions and highly conserved transcription start and stop signal sequences. The P gene expression strategy of ASPV was like that of the respiro-, morbilli- and henipaviruses, which express the P and C proteins from the primary transcript and edit a portion of the mRNA to encode V and W proteins. Sequence similarities among various features related to virus replication, pairwise comparisons of all deduced ASPV protein sequences with homologous regions from other members of the family Paramyxoviridae, and phylogenetic analyses of these amino acid sequences suggested that ASPV was a novel member of the sub-family Paramyxovirinae, most closely related to the respiroviruses. ?? 2008 Elsevier B.V. All rights reserved.
Inhibition of hepatitis B virus replication with linear DNA sequences expressing antiviral micro-RNA shuttles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chattopadhyay, Saket; Ely, Abdullah; Bloom, Kristie

2009-11-20

RNA interference (RNAi) may be harnessed to inhibit viral gene expression and this approach is being developed to counter chronic infection with hepatitis B virus (HBV). Compared to synthetic RNAi activators, DNA expression cassettes that generate silencing sequences have advantages of sustained efficacy and ease of propagation in plasmid DNA (pDNA). However, the large size of pDNAs and inclusion of sequences conferring antibiotic resistance and immunostimulation limit delivery efficiency and safety. To develop use of alternative DNA templates that may be applied for therapeutic gene silencing, we assessed the usefulness of PCR-generated linear expression cassettes that produce anti-HBV micro-RNA (miR)more » shuttles. We found that silencing of HBV markers of replication was efficient (>75%) in cell culture and in vivo. miR shuttles were processed to form anti-HBV guide strands and there was no evidence of induction of the interferon response. Modification of terminal sequences to include flanking human adenoviral type-5 inverted terminal repeats was easily achieved and did not compromise silencing efficacy. These linear DNA sequences should have utility in the development of gene silencing applications where modifications of terminal elements with elimination of potentially harmful and non-essential sequences are required.« less
The expanding polymerase universe.

PubMed

Goodman, M F; Tippin, B

2000-11-01

Over the past year, the number of known prokaryotic and eukaryotic DNA polymerases has exploded. Many of these newly discovered enzymes copy aberrant bases in the DNA template over which 'respectable' polymerases fear to tread. The next step is to unravel their functions, which are thought to range from error-prone copying of DNA lesions, somatic hypermutation and avoidance of skin cancer, to restarting stalled replication forks and repairing double-stranded DNA breaks.
Molecular epidemiological analysis of env and pol sequences in newly diagnosed HIV type 1-infected, untreated patients in Hungary.

PubMed

Mezei, Mária; Ay, Eva; Koroknai, Anita; Tóth, Renáta; Balázs, Andrea; Bakos, Agnes; Gyori, Zoltán; Bánáti, Ferenc; Marschalkó, Márta; Kárpáti, Sarolta; Minárovits, János

2011-11-01

The aim of our study was to monitor the diversity of HIV-1 strains circulating in Hungary and investigate the prevalence of resistance-associated mutations to reverse transcriptase (RT) and protease (PR) inhibitors in newly diagnosed, drug-naive patients. A total of 30 HIV-1-infected patients without prior antiretroviral treatment diagnosed during the period 2008-2010 were included into this study. Viral subtypes and the presence of RT, PR resistance-associated mutations were established by sequencing. Classification of HIV-1 strains showed that 29 (96.6%) patients were infected with subtype B viruses and one patient (3.3%) with subtype A virus. The prevalence of HIV-1 strains with transmitted drug resistance mutations in newly diagnosed individuals was 16.6% (5/30). This study showed that HIV-1 subtype B is still highly predominant in Hungary and documented a relatively high transmission rate of drug resistance in our country.
The power and promise of RNA-seq in ecology and evolution.

PubMed

Todd, Erica V; Black, Michael A; Gemmell, Neil J

2016-03-01

Reference is regularly made to the power of new genomic sequencing approaches. Using powerful technology, however, is not the same as having the necessary power to address a research question with statistical robustness. In the rush to adopt new and improved genomic research methods, limitations of technology and experimental design may be initially neglected. Here, we review these issues with regard to RNA sequencing (RNA-seq). RNA-seq adds large-scale transcriptomics to the toolkit of ecological and evolutionary biologists, enabling differential gene expression (DE) studies in nonmodel species without the need for prior genomic resources. High biological variance is typical of field-based gene expression studies and means that larger sample sizes are often needed to achieve the same degree of statistical power as clinical studies based on data from cell lines or inbred animal models. Sequencing costs have plummeted, yet RNA-seq studies still underutilize biological replication. Finite research budgets force a trade-off between sequencing effort and replication in RNA-seq experimental design. However, clear guidelines for negotiating this trade-off, while taking into account study-specific factors affecting power, are currently lacking. Study designs that prioritize sequencing depth over replication fail to capitalize on the power of RNA-seq technology for DE inference. Significant recent research effort has gone into developing statistical frameworks and software tools for power analysis and sample size calculation in the context of RNA-seq DE analysis. We synthesize progress in this area and derive an accessible rule-of-thumb guide for designing powerful RNA-seq experiments relevant in eco-evolutionary and clinical settings alike. © 2016 John Wiley & Sons Ltd.
Genome-wide alterations of the DNA replication program during tumor progression

NASA Astrophysics Data System (ADS)

Arneodo, A.; Goldar, A.; Argoul, F.; Hyrien, O.; Audit, B.

2016-08-01

Oncogenic stress is a major driving force in the early stages of cancer development. Recent experimental findings reveal that, in precancerous lesions and cancers, activated oncogenes may induce stalling and dissociation of DNA replication forks resulting in DNA damage. Replication timing is emerging as an important epigenetic feature that recapitulates several genomic, epigenetic and functional specificities of even closely related cell types. There is increasing evidence that chromosome rearrangements, the hallmark of many cancer genomes, are intimately associated with the DNA replication program and that epigenetic replication timing changes often precede chromosomic rearrangements. The recent development of a novel methodology to map replication fork polarity using deep sequencing of Okazaki fragments has provided new and complementary genome-wide replication profiling data. We review the results of a wavelet-based multi-scale analysis of genomic and epigenetic data including replication profiles along human chromosomes. These results provide new insight into the spatio-temporal replication program and its dynamics during differentiation. Here our goal is to bring to cancer research, the experimental protocols and computational methodologies for replication program profiling, and also the modeling of the spatio-temporal replication program. To illustrate our purpose, we report very preliminary results obtained for the chronic myelogeneous leukemia, the archetype model of cancer. Finally, we discuss promising perspectives on using genome-wide DNA replication profiling as a novel efficient tool for cancer diagnosis, prognosis and personalized treatment.

Mother-to-Child HIV Transmission Bottleneck Selects for Consensus Virus with Lower Gag-Protease-Driven Replication Capacity

PubMed Central

Naidoo, Vanessa L.; Mann, Jaclyn K.; Noble, Christie; Adland, Emily; Carlson, Jonathan M.; Thomas, Jake; Brumme, Chanson J.; Thobakgale-Tshabalala, Christina F.; Brumme, Zabrina L.; Goulder, Philip J. R.

2017-01-01

ABSTRACT In the large majority of cases, HIV infection is established by a single variant, and understanding the characteristics of successfully transmitted variants is relevant to prevention strategies. Few studies have investigated the viral determinants of mother-to-child transmission. To determine the impact of Gag-protease-driven viral replication capacity on mother-to-child transmission, the replication capacities of 148 recombinant viruses encoding plasma-derived Gag-protease from 53 nontransmitter mothers, 48 transmitter mothers, and 47 infected infants were assayed in an HIV-1-inducible green fluorescent protein reporter cell line. All study participants were infected with HIV-1 subtype C. There was no significant difference in replication capacities between the nontransmitter (n = 53) and transmitter (n = 44) mothers (P = 0.48). Infant-derived Gag-protease NL4-3 recombinant viruses (n = 41) were found to have a significantly lower Gag-protease-driven replication capacity than that of viruses derived from the mothers (P < 0.0001 by a paired t test). High percent similarities to consensus subtype C Gag, p17, p24, and protease sequences were also found in the infants (n = 28) in comparison to their mothers (P = 0.07, P = 0.002, P = 0.03, and P = 0.02, respectively, as determined by a paired t test). These data suggest that of the viral quasispecies found in mothers, the HIV mother-to-child transmission bottleneck favors the transmission of consensus-like viruses with lower viral replication capacities. IMPORTANCE Understanding the characteristics of successfully transmitted HIV variants has important implications for preventative interventions. Little is known about the viral determinants of HIV mother-to-child transmission (MTCT). We addressed the role of viral replication capacity driven by Gag, a major structural protein that is a significant determinant of overall viral replicative ability and an important target of the host immune response, in the MTCT bottleneck. This study advances our understanding of the genetic bottleneck in MTCT by revealing that viruses transmitted to infants have a lower replicative ability as well as a higher similarity to the population consensus (in this case HIV subtype C) than those of their mothers. Furthermore, the observation that “consensus-like” virus sequences correspond to lower in vitro replication abilities yet appear to be preferentially transmitted suggests that viral characteristics favoring transmission are decoupled from those that enhance replicative capacity. PMID:28637761
A 5.8S nuclear ribosomal RNA gene sequence database: applications to ecology and evolution

NASA Technical Reports Server (NTRS)

Cullings, K. W.; Vogler, D. R.

1998-01-01

We complied a 5.8S nuclear ribosomal gene sequence database for animals, plants, and fungi using both newly generated and GenBank sequences. We demonstrate the utility of this database as an internal check to determine whether the target organism and not a contaminant has been sequenced, as a diagnostic tool for ecologists and evolutionary biologists to determine the placement of asexual fungi within larger taxonomic groups, and as a tool to help identify fungi that form ectomycorrhizae.
Sequence variants in the autophagy gene IRGM and multiple other replicating loci contribute to Crohn disease susceptibility

PubMed Central

Parkes, Miles; Barrett, Jeffrey C; Prescott, Natalie; Tremelling, Mark; Anderson, Carl A; Fisher, Sheila A; Roberts, Roland G; Nimmo, Elaine R; Cummings, Fraser R; Soars, Dianne; Drummond, Hazel; Lees, Charlie W; Khawaja, Saud A; Bagnall, Richard; Burke, Denis A; Todhunter, Catherine E; Ahmad, Tariq; Onnie, Clive M; McArdle, Wendy; Strachan, David; Bethel, Graeme; Bryan, Claire; Deloukas, Panos; Forbes, Alastair; Sanderson, Jeremy; Jewell, Derek P; Satsangi, Jack; Mansfield, John C; Cardon, Lon; Mathew, Christopher G

2008-01-01

A genome-wide association scan in Crohn disease by the Wellcome Trust Case Control Consortium1 detected strong association at 6 novel loci. We tested 37 SNPs from these and other loci for association in an independent case control sample. Replication was obtained for the IRGM gene on chromosome 5q33.1 which induces autophagy (replication P = 6.6 × 10−4, combined P = 2.1 × 10−10), and for 9 other loci including NKX2-3 and gene deserts on chromosomes 1q and 5p13. PMID:17554261
Inhibition of Human Immunodeficiency Virus Replication by Antisense Oligodeoxynucleotides

NASA Astrophysics Data System (ADS)

Goodchild, John; Agrawal, Sudhir; Civeira, Maria P.; Sarin, Prem S.; Sun, Daisy; Zamecnik, Paul C.

1988-08-01

Twenty different target sites within human immunodeficiency virus (HIV) RNA were selected for studies of inhibition of HIV replication by antisense oligonucleotides. Target sites were selected based on their potential capacity to block recognition functions during viral replication. Antisense oligomers complementary to sites within or near the sequence repeated at the ends of retrovirus RNA (R region) and to certain splice sites were most effective. The effect of antisense oligomer length on inhibiting virus replication was also investigated, and preliminary toxicity studies in mice show that these compounds are toxic only at high levels. The results indicate potential usefulness for these oligomers in the treatment of patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related complex either alone or in combination with other drugs.
The infectivities of turnip yellow mosaic virus genomes with altered tRNA mimicry are not dependent on compensating mutations in the viral replication protein.

PubMed

Filichkin, S A; Bransom, K L; Goodwin, J B; Dreher, T W

2000-09-01

Five highly infectious turnip yellow mosaic virus (TYMV) genomes with sequence changes in their 3'-terminal regions that result in altered aminoacylation and eEF1A binding have been studied. These genomes were derived from cloned parental RNAs of low infectivity by sequential passaging in plants. Three of these genomes that are incapable of aminoacylation have been reported previously (J. B. Goodwin, J. M. Skuzeski, and T. W. Dreher, Virology 230:113-124, 1997). We now demonstrate by subcloning the 3' untranslated regions into wild-type TYMV RNA that the high infectivities and replication rates of these genomes compared to their progenitors are mostly due to a small number of mutations acquired in the 3' tRNA-like structure during passaging. Mutations in other parts of the genome, including the replication protein coding region, are not required for high infectivity but probably do play a role in optimizing viral amplification and spread in plants. Two other TYMV RNA variants of suboptimal infectivities, one that accepts methionine instead of the usual valine and one that interacts less tightly with eEF1A, were sequentially passaged to produce highly infectious genomes. The improved infectivities of these RNAs were not associated with increased replication in protoplasts, and no mutations were acquired in their 3' tRNA-like structures. Complete sequencing of one genome identified two mutations that result in amino acid changes in the movement protein gene, suggesting that improved infectivity may be a function of improved viral dissemination in plants. Our results show that the wild-type TYMV replication proteins are able to amplify genomes with 3' termini of variable sequence and tRNA mimicry. These and previous results have led to a model in which the binding of eEF1A to the 3' end to antagonize minus-strand initiation is a major role of the tRNA-like structure.
Exome Sequencing and the Management of Neurometabolic Disorders.

PubMed

Tarailo-Graovac, Maja; Shyr, Casper; Ross, Colin J; Horvath, Gabriella A; Salvarinova, Ramona; Ye, Xin C; Zhang, Lin-Hua; Bhavsar, Amit P; Lee, Jessica J Y; Drögemöller, Britt I; Abdelsayed, Mena; Alfadhel, Majid; Armstrong, Linlea; Baumgartner, Matthias R; Burda, Patricie; Connolly, Mary B; Cameron, Jessie; Demos, Michelle; Dewan, Tammie; Dionne, Janis; Evans, A Mark; Friedman, Jan M; Garber, Ian; Lewis, Suzanne; Ling, Jiqiang; Mandal, Rupasri; Mattman, Andre; McKinnon, Margaret; Michoulas, Aspasia; Metzger, Daniel; Ogunbayo, Oluseye A; Rakic, Bojana; Rozmus, Jacob; Ruben, Peter; Sayson, Bryan; Santra, Saikat; Schultz, Kirk R; Selby, Kathryn; Shekel, Paul; Sirrs, Sandra; Skrypnyk, Cristina; Superti-Furga, Andrea; Turvey, Stuart E; Van Allen, Margot I; Wishart, David; Wu, Jiang; Wu, John; Zafeiriou, Dimitrios; Kluijtmans, Leo; Wevers, Ron A; Eydoux, Patrice; Lehman, Anna M; Vallance, Hilary; Stockler-Ipsiroglu, Sylvia; Sinclair, Graham; Wasserman, Wyeth W; van Karnebeek, Clara D

2016-06-09

Whole-exome sequencing has transformed gene discovery and diagnosis in rare diseases. Translation into disease-modifying treatments is challenging, particularly for intellectual developmental disorder. However, the exception is inborn errors of metabolism, since many of these disorders are responsive to therapy that targets pathophysiological features at the molecular or cellular level. To uncover the genetic basis of potentially treatable inborn errors of metabolism, we combined deep clinical phenotyping (the comprehensive characterization of the discrete components of a patient's clinical and biochemical phenotype) with whole-exome sequencing analysis through a semiautomated bioinformatics pipeline in consecutively enrolled patients with intellectual developmental disorder and unexplained metabolic phenotypes. We performed whole-exome sequencing on samples obtained from 47 probands. Of these patients, 6 were excluded, including 1 who withdrew from the study. The remaining 41 probands had been born to predominantly nonconsanguineous parents of European descent. In 37 probands, we identified variants in 2 genes newly implicated in disease, 9 candidate genes, 22 known genes with newly identified phenotypes, and 9 genes with expected phenotypes; in most of the genes, the variants were classified as either pathogenic or probably pathogenic. Complex phenotypes of patients in five families were explained by coexisting monogenic conditions. We obtained a diagnosis in 28 of 41 probands (68%) who were evaluated. A test of a targeted intervention was performed in 18 patients (44%). Deep phenotyping and whole-exome sequencing in 41 probands with intellectual developmental disorder and unexplained metabolic abnormalities led to a diagnosis in 68%, the identification of 11 candidate genes newly implicated in neurometabolic disease, and a change in treatment beyond genetic counseling in 44%. (Funded by BC Children's Hospital Foundation and others.).
Exome Sequencing and the Management of Neurometabolic Disorders

PubMed Central

Tarailo-Graovac, M.; Shyr, C.; Ross, C.J.; Horvath, G.A.; Salvarinova, R.; Ye, X.C.; Zhang, L.-H.; Bhavsar, A.P.; Lee, J.J.Y.; Drögemöller, B.I.; Abdelsayed, M.; Alfadhel, M.; Armstrong, L.; Baumgartner, M.R.; Burda, P.; Connolly, M.B.; Cameron, J.; Demos, M.; Dewan, T.; Dionne, J.; Evans, A.M.; Friedman, J.M.; Garber, I.; Lewis, S.; Ling, J.; Mandal, R.; Mattman, A.; McKinnon, M.; Michoulas, A.; Metzger, D.; Ogunbayo, O.A.; Rakic, B.; Rozmus, J.; Ruben, P.; Sayson, B.; Santra, S.; Schultz, K.R.; Selby, K.; Shekel, P.; Sirrs, S.; Skrypnyk, C.; Superti-Furga, A.; Turvey, S.E.; Van Allen, M.I.; Wishart, D.; Wu, J.; Wu, J.; Zafeiriou, D.; Kluijtmans, L.; Wevers, R.A.; Eydoux, P.; Lehman, A.M.; Vallance, H.; Stockler-Ipsiroglu, S.; Sinclair, G.; Wasserman, W.W.; van Karnebeek, C.D.

2016-01-01

BACKGROUND Whole-exome sequencing has transformed gene discovery and diagnosis in rare diseases. Translation into disease-modifying treatments is challenging, particularly for intellectual developmental disorder. However, the exception is inborn errors of metabolism, since many of these disorders are responsive to therapy that targets pathophysiological features at the molecular or cellular level. METHODS To uncover the genetic basis of potentially treatable inborn errors of metabolism, we combined deep clinical phenotyping (the comprehensive characterization of the discrete components of a patient’s clinical and biochemical phenotype) with whole-exome sequencing analysis through a semiautomated bioinformatics pipeline in consecutively enrolled patients with intellectual developmental disorder and unexplained metabolic phenotypes. RESULTS We performed whole-exome sequencing on samples obtained from 47 probands. Of these patients, 6 were excluded, including 1 who withdrew from the study. The remaining 41 probands had been born to predominantly nonconsanguineous parents of European descent. In 37 probands, we identified variants in 2 genes newly implicated in disease, 9 candidate genes, 22 known genes with newly identified phenotypes, and 9 genes with expected phenotypes; in most of the genes, the variants were classified as either pathogenic or probably pathogenic. Complex phenotypes of patients in five families were explained by coexisting monogenic conditions. We obtained a diagnosis in 28 of 41 probands (68%) who were evaluated. A test of a targeted intervention was performed in 18 patients (44%). CONCLUSIONS Deep phenotyping and whole-exome sequencing in 41 probands with intellectual developmental disorder and unexplained metabolic abnormalities led to a diagnosis in 68%, the identification of 11 candidate genes newly implicated in neurometabolic disease, and a change in treatment beyond genetic counseling in 44%. (Funded by BC Children’s Hospital Foundation and others.) PMID:27276562
Genome-wide association study identifies three new melanoma susceptibility loci.

PubMed

Barrett, Jennifer H; Iles, Mark M; Harland, Mark; Taylor, John C; Aitken, Joanne F; Andresen, Per Arne; Akslen, Lars A; Armstrong, Bruce K; Avril, Marie-Francoise; Azizi, Esther; Bakker, Bert; Bergman, Wilma; Bianchi-Scarrà, Giovanna; Bressac-de Paillerets, Brigitte; Calista, Donato; Cannon-Albright, Lisa A; Corda, Eve; Cust, Anne E; Dębniak, Tadeusz; Duffy, David; Dunning, Alison M; Easton, Douglas F; Friedman, Eitan; Galan, Pilar; Ghiorzo, Paola; Giles, Graham G; Hansson, Johan; Hocevar, Marko; Höiom, Veronica; Hopper, John L; Ingvar, Christian; Janssen, Bart; Jenkins, Mark A; Jönsson, Göran; Kefford, Richard F; Landi, Giorgio; Landi, Maria Teresa; Lang, Julie; Lubiński, Jan; Mackie, Rona; Malvehy, Josep; Martin, Nicholas G; Molven, Anders; Montgomery, Grant W; van Nieuwpoort, Frans A; Novakovic, Srdjan; Olsson, Håkan; Pastorino, Lorenza; Puig, Susana; Puig-Butille, Joan Anton; Randerson-Moor, Juliette; Snowden, Helen; Tuominen, Rainer; Van Belle, Patricia; van der Stoep, Nienke; Whiteman, David C; Zelenika, Diana; Han, Jiali; Fang, Shenying; Lee, Jeffrey E; Wei, Qingyi; Lathrop, G Mark; Gillanders, Elizabeth M; Brown, Kevin M; Goldstein, Alisa M; Kanetsky, Peter A; Mann, Graham J; Macgregor, Stuart; Elder, David E; Amos, Christopher I; Hayward, Nicholas K; Gruis, Nelleke A; Demenais, Florence; Bishop, Julia A Newton; Bishop, D Timothy

2011-10-09

We report a genome-wide association study for melanoma that was conducted by the GenoMEL Consortium. Our discovery phase included 2,981 individuals with melanoma and 1,982 study-specific control individuals of European ancestry, as well as an additional 6,426 control subjects from French or British populations, all of whom were genotyped for 317,000 or 610,000 single-nucleotide polymorphisms (SNPs). Our analysis replicated previously known melanoma susceptibility loci. Seven new regions with at least one SNP with P < 10(-5) and further local imputed or genotyped support were selected for replication using two other genome-wide studies (from Australia and Texas, USA). Additional replication came from case-control series from the UK and The Netherlands. Variants at three of the seven loci replicated at P < 10(-3): an SNP in ATM (rs1801516, overall P = 3.4 × 10(-9)), an SNP in MX2 (rs45430, P = 2.9 × 10(-9)) and an SNP adjacent to CASP8 (rs13016963, P = 8.6 × 10(-10)). A fourth locus near CCND1 remains of potential interest, showing suggestive but inconclusive evidence of replication (rs1485993, overall P = 4.6 × 10(-7) under a fixed-effects model and P = 1.2 × 10(-3) under a random-effects model). These newly associated variants showed no association with nevus or pigmentation phenotypes in a large British case-control series.
Cazymes Analysis Toolkit (CAT): Webservice for searching and analyzing carbohydrateactive enzymes in a newly sequenced organism using CAZy database

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karpinets, Tatiana V; Park, Byung; Syed, Mustafa H

2010-01-01

The Carbohydrate-Active Enzyme (CAZy) database provides a rich set of manually annotated enzymes that degrade, modify, or create glycosidic bonds. Despite rich and invaluable information stored in the database, software tools utilizing this information for annotation of newly sequenced genomes by CAZy families are limited. We have employed two annotation approaches to fill the gap between manually curated high-quality protein sequences collected in the CAZy database and the growing number of other protein sequences produced by genome or metagenome sequencing projects. The first approach is based on a similarity search against the entire non-redundant sequences of the CAZy database. Themore » second approach performs annotation using links or correspondences between the CAZy families and protein family domains. The links were discovered using the association rule learning algorithm applied to sequences from the CAZy database. The approaches complement each other and in combination achieved high specificity and sensitivity when cross-evaluated with the manually curated genomes of Clostridium thermocellum ATCC 27405 and Saccharophagus degradans 2-40. The capability of the proposed framework to predict the function of unknown protein domains (DUF) and of hypothetical proteins in the genome of Neurospora crassa is demonstrated. The framework is implemented as a Web service, the CAZymes Analysis Toolkit (CAT), and is available at http://cricket.ornl.gov/cgi-bin/cat.cgi.« less
CAZymes Analysis Toolkit (CAT): web service for searching and analyzing carbohydrate-active enzymes in a newly sequenced organism using CAZy database.

PubMed

Park, Byung H; Karpinets, Tatiana V; Syed, Mustafa H; Leuze, Michael R; Uberbacher, Edward C

2010-12-01

The Carbohydrate-Active Enzyme (CAZy) database provides a rich set of manually annotated enzymes that degrade, modify, or create glycosidic bonds. Despite rich and invaluable information stored in the database, software tools utilizing this information for annotation of newly sequenced genomes by CAZy families are limited. We have employed two annotation approaches to fill the gap between manually curated high-quality protein sequences collected in the CAZy database and the growing number of other protein sequences produced by genome or metagenome sequencing projects. The first approach is based on a similarity search against the entire nonredundant sequences of the CAZy database. The second approach performs annotation using links or correspondences between the CAZy families and protein family domains. The links were discovered using the association rule learning algorithm applied to sequences from the CAZy database. The approaches complement each other and in combination achieved high specificity and sensitivity when cross-evaluated with the manually curated genomes of Clostridium thermocellum ATCC 27405 and Saccharophagus degradans 2-40. The capability of the proposed framework to predict the function of unknown protein domains and of hypothetical proteins in the genome of Neurospora crassa is demonstrated. The framework is implemented as a Web service, the CAZymes Analysis Toolkit, and is available at http://cricket.ornl.gov/cgi-bin/cat.cgi.
Genome-wide Control of Heterochromatin Replication by the Telomere Capping Protein TRF2.

PubMed

Mendez-Bermudez, Aaron; Lototska, Liudmyla; Bauwens, Serge; Giraud-Panis, Marie-Josèphe; Croce, Olivier; Jamet, Karine; Irizar, Agurtzane; Mowinckel, Macarena; Koundrioukoff, Stephane; Nottet, Nicolas; Almouzni, Genevieve; Teulade-Fichou, Mare-Paule; Schertzer, Michael; Perderiset, Mylène; Londoño-Vallejo, Arturo; Debatisse, Michelle; Gilson, Eric; Ye, Jing

2018-05-03

Hard-to-replicate regions of chromosomes (e.g., pericentromeres, centromeres, and telomeres) impede replication fork progression, eventually leading, in the event of replication stress, to chromosome fragility, aging, and cancer. Our knowledge of the mechanisms controlling the stability of these regions is essentially limited to telomeres, where fragility is counteracted by the shelterin proteins. Here we show that the shelterin subunit TRF2 ensures progression of the replication fork through pericentromeric heterochromatin, but not centromeric chromatin. In a process involving its N-terminal basic domain, TRF2 binds to pericentromeric Satellite III sequences during S phase, allowing the recruitment of the G-quadruplex-resolving helicase RTEL1 to facilitate fork progression. We also show that TRF2 is required for the stability of other heterochromatic regions localized throughout the genome, paving the way for future research on heterochromatic replication and its relationship with aging and cancer. Copyright © 2018 Elsevier Inc. All rights reserved.
Identification of Novel Kaposi's Sarcoma-Associated Herpesvirus Orf50 Transcripts: Discovery of New RTA Isoforms with Variable Transactivation Potential

PubMed Central

Wakeman, Brian S.; Izumiya, Yoshihiro

2016-01-01

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV) is a gammaherpesvirus that has been associated with primary effusion lymphoma and multicentric Castleman's disease, as well as its namesake Kaposi's sarcoma. As a gammaherpesvirus, KSHV is able to acutely replicate, enter latency, and reactivate from this latent state. A key protein involved in both acute replication and reactivation from latency is the replication and transcriptional activator (RTA) encoded by the gene Orf50. RTA is a known transactivator of multiple viral genes, allowing it to control the switch between latency and virus replication. We report here the identification of six alternatively spliced Orf50 transcripts that are generated from four distinct promoters. These newly identified promoters are shown to be transcriptionally active in 293T (embryonic kidney), Vero (African-green monkey kidney epithelial), 3T12 (mouse fibroblast), and RAW 264.7 (mouse macrophage) cell lines. Notably, the newly identified Orf50 transcripts are predicted to encode four different isoforms of the RTA which differ by 6 to 10 residues at the amino terminus of the protein. We show the global viral transactivation potential of all four RTA isoforms and demonstrate that all isoforms can transcriptionally activate an array of KSHV promoters to various levels. The pattern of transcriptional activation appears to support a transcriptional interference model within the Orf50 region, where silencing of previously expressed isoforms by transcription initiation from upstream Orf50 promoters has the potential to modulate the pattern of viral gene activation. IMPORTANCE Gammaherpesviruses are associated with the development of lymphomas and lymphoproliferative diseases, as well as several other types of cancer. The human gammaherpesvirus, Kaposi's sarcoma-associated herpesvirus (KSHV), is tightly associated with the development of Kaposi's sarcoma and multicentric Castleman's disease, as well as a rare form of B cell lymphoma (primary effusion lymphoma) primarily observed in HIV-infected individuals. RTA is an essential viral gene product involved in the initiation of gammaherpesvirus replication and is conserved among all known gammaherpesviruses. We show here for KSHV that transcription of the gene encoding RTA is complex and leads to the expression of several isoforms of RTA with distinct functions. This observed complexity in KSHV RTA expression and function likely plays a critical role in the regulation of downstream viral and cellular gene expression, leading to the efficient production of mature virions. PMID:27795414
Influence of genome-scale RNA structure disruption on the replication of murine norovirus—similar replication kinetics in cell culture but attenuation of viral fitness in vivo

PubMed Central

McFadden, Nora; Arias, Armando; Dry, Inga; Bailey, Dalan; Witteveldt, Jeroen; Evans, David J.; Goodfellow, Ian; Simmonds, Peter

2013-01-01

Mechanisms by which certain RNA viruses, such as hepatitis C virus, establish persistent infections and cause chronic disease are of fundamental importance in viral pathogenesis. Mammalian positive-stranded RNA viruses establishing persistence typically possess genome-scale ordered RNA secondary structure (GORS) in their genomes. Murine norovirus (MNV) persists in immunocompetent mice and provides an experimental model to functionally characterize GORS. Substitution mutants were constructed with coding sequences in NS3/4- and NS6/7-coding regions replaced with sequences with identical coding and (di-)nucleotide composition but disrupted RNA secondary structure (F1, F2, F1/F2 mutants). Mutants replicated with similar kinetics to wild-type (WT) MNV3 in RAW264.7 cells and primary macrophages, exhibited similar (highly restricted) induction and susceptibility to interferon-coupled cellular responses and equal replication fitness by serial passaging of co-cultures. In vivo, both WT and F1/F2 mutant viruses persistently infected mice, although F1, F2 and F1/F2 mutant viruses were rapidly eliminated 1–7 days post-inoculation in competition experiments with WT. F1/F2 mutants recovered from tissues at 9 months showed higher synonymous substitution rates than WT and nucleotide substitutions that potentially restored of RNA secondary structure. GORS plays no role in basic replication of MNV but potentially contributes to viral fitness and persistence in vivo. PMID:23630317
Fatal Metacestode Infection in Bornean Orangutan Caused by Unknown Versteria Species

PubMed Central

Gendron-Fitzpatrick, Annette; Deering, Kathleen M.; Wallace, Roberta S.; Clyde, Victoria L.; Lauck, Michael; Rosen, Gail E.; Bennett, Andrew J.; Greiner, Ellis C.; O’Connor, David H.

2014-01-01

A captive juvenile Bornean orangutan (Pongo pygmaeus) died from an unknown disseminated parasitic infection. Deep sequencing of DNA from infected tissues, followed by gene-specific PCR and sequencing, revealed a divergent species within the newly proposed genus Versteria (Cestoda: Taeniidae). Versteria may represent a previously unrecognized risk to primate health. PMID:24377497
Efficient Feature Selection and Classification of Protein Sequence Data in Bioinformatics

PubMed Central

Faye, Ibrahima; Samir, Brahim Belhaouari; Md Said, Abas

2014-01-01

Bioinformatics has been an emerging area of research for the last three decades. The ultimate aims of bioinformatics were to store and manage the biological data, and develop and analyze computational tools to enhance their understanding. The size of data accumulated under various sequencing projects is increasing exponentially, which presents difficulties for the experimental methods. To reduce the gap between newly sequenced protein and proteins with known functions, many computational techniques involving classification and clustering algorithms were proposed in the past. The classification of protein sequences into existing superfamilies is helpful in predicting the structure and function of large amount of newly discovered proteins. The existing classification results are unsatisfactory due to a huge size of features obtained through various feature encoding methods. In this work, a statistical metric-based feature selection technique has been proposed in order to reduce the size of the extracted feature vector. The proposed method of protein classification shows significant improvement in terms of performance measure metrics: accuracy, sensitivity, specificity, recall, F-measure, and so forth. PMID:25045727
Subtype-Specific Differences in Gag-Protease-Driven Replication Capacity Are Consistent with Intersubtype Differences in HIV-1 Disease Progression.

PubMed

Kiguoya, Marion W; Mann, Jaclyn K; Chopera, Denis; Gounder, Kamini; Lee, Guinevere Q; Hunt, Peter W; Martin, Jeffrey N; Ball, T Blake; Kimani, Joshua; Brumme, Zabrina L; Brockman, Mark A; Ndung'u, Thumbi

2017-07-01

There are marked differences in the spread and prevalence of HIV-1 subtypes worldwide, and differences in clinical progression have been reported. However, the biological reasons underlying these differences are unknown. Gag-protease is essential for HIV-1 replication, and Gag-protease-driven replication capacity has previously been correlated with disease progression. We show that Gag-protease replication capacity correlates significantly with that of whole isolates ( r = 0.51; P = 0.04), indicating that Gag-protease is a significant contributor to viral replication capacity. Furthermore, we investigated subtype-specific differences in Gag-protease-driven replication capacity using large well-characterized cohorts in Africa and the Americas. Patient-derived Gag-protease sequences were inserted into an HIV-1 NL4-3 backbone, and the replication capacities of the resulting recombinant viruses were measured in an HIV-1-inducible reporter T cell line by flow cytometry. Recombinant viruses expressing subtype C Gag-proteases exhibited substantially lower replication capacities than those expressing subtype B Gag-proteases ( P < 0.0001); this observation remained consistent when representative Gag-protease sequences were engineered into an HIV-1 subtype C backbone. We identified Gag residues 483 and 484, located within the Alix-binding motif involved in virus budding, as major contributors to subtype-specific replicative differences. In East African cohorts, we observed a hierarchy of Gag-protease-driven replication capacities, i.e., subtypes A/C < D < intersubtype recombinants ( P < 0.0029), which is consistent with reported intersubtype differences in disease progression. We thus hypothesize that the lower Gag-protease-driven replication capacity of subtypes A and C slows disease progression in individuals infected with these subtypes, which in turn leads to greater opportunity for transmission and thus increased prevalence of these subtypes. IMPORTANCE HIV-1 subtypes are unevenly distributed globally, and there are reported differences in their rates of disease progression and epidemic spread. The biological determinants underlying these differences have not been fully elucidated. Here, we show that HIV-1 Gag-protease-driven replication capacity correlates with the replication capacity of whole virus isolates. We further show that subtype B displays a significantly higher Gag-protease-mediated replication capacity than does subtype C, and we identify a major genetic determinant of these differences. Moreover, in two independent East African cohorts we demonstrate a reproducible hierarchy of Gag-protease-driven replicative capacity, whereby recombinants exhibit the greatest replication, followed by subtype D, followed by subtypes A and C. Our data identify Gag-protease as a major determinant of subtype differences in disease progression among HIV-1 subtypes; furthermore, we propose that the poorer viral replicative capacity of subtypes A and C may paradoxically contribute to their more efficient spread in sub-Saharan Africa. Copyright © 2017 American Society for Microbiology.
Specific functions of the Rep and Rep׳ proteins of porcine circovirus during copy-release and rolling-circle DNA replication.

PubMed

Cheung, Andrew K

2015-07-01

The roles of two porcine circovirus replication initiator proteins, Rep and Rep׳, in generating copy-release and rolling-circle DNA replication intermediates were determined. Rep uses the supercoiled closed-circular genome (ccc) to initiate leading-strand synthesis (identical to copy-release replication) and generates the single-stranded circular (ssc) genome from the displaced DNA strand. In the process, a minus-genome primer (MGP) necessary for complementary-strand synthesis, from ssc to ccc, is synthesized. Rep׳ cleaves the growing nascent-strand to regenerate the parent ccc molecule. In the process, a Rep׳-DNA hybrid containing the right palindromic sequence (at the origin of DNA replication) is generated. Analysis of the virus particle showed that it is composed of four components: ssc, MGP, capsid protein and a novel Rep-related protein (designated Protein-3). Copyright © 2015. Published by Elsevier Inc.
Sequence analysis of malacoherpesvirus proteins: Pan-herpesvirus capsid module and replication enzymes with an ancient connection to "Megavirales".

PubMed

Mushegian, Arcady; Karin, Eli Levy; Pupko, Tal

2018-01-01

The order Herpesvirales includes animal viruses with large double-strand DNA genomes replicating in the nucleus. The main capsid protein in the best-studied family Herpesviridae contains a domain with HK97-like fold related to bacteriophage head proteins, and several virion maturation factors are also homologous between phages and herpesviruses. The origin of herpesvirus DNA replication proteins is less well understood. While analyzing the genomes of herpesviruses in the family Malacohepresviridae, we identified nearly 30 families of proteins conserved in other herpesviruses, including several phage-related domains in morphogenetic proteins. Herpesvirus DNA replication factors have complex evolutionary history: some are related to cellular proteins, but others are closer to homologs from large nucleocytoplasmic DNA viruses. Phylogenetic analyses suggest that the core replication machinery of herpesviruses may have been recruited from the same pool as in the case of other large DNA viruses of eukaryotes. Published by Elsevier Inc.
Spontaneous Chloroplast Mutants Mostly Occur by Replication Slippage and Show a Biased Pattern in the Plastome of Oenothera[OPEN

PubMed Central

Massouh, Amid; Schubert, Julia; Yaneva-Roder, Liliya; Ulbricht-Jones, Elena S.; Johnson, Marc T.J.; Wright, Stephen I.; Pellizzer, Tommaso; Sobanski, Johanna; Greiner, Stephan

2016-01-01

Spontaneous plastome mutants have been used as a research tool since the beginning of genetics. However, technical restrictions have severely limited their contributions to research in physiology and molecular biology. Here, we used full plastome sequencing to systematically characterize a collection of 51 spontaneous chloroplast mutants in Oenothera (evening primrose). Most mutants carry only a single mutation. Unexpectedly, the vast majority of mutations do not represent single nucleotide polymorphisms but are insertions/deletions originating from DNA replication slippage events. Only very few mutations appear to be caused by imprecise double-strand break repair, nucleotide misincorporation during replication, or incorrect nucleotide excision repair following oxidative damage. U-turn inversions were not detected. Replication slippage is induced at repetitive sequences that can be very small and tend to have high A/T content. Interestingly, the mutations are not distributed randomly in the genome. The underrepresentation of mutations caused by faulty double-strand break repair might explain the high structural conservation of seed plant plastomes throughout evolution. In addition to providing a fully characterized mutant collection for future research on plastid genetics, gene expression, and photosynthesis, our work identified the spectrum of spontaneous mutations in plastids and reveals that this spectrum is very different from that in the nucleus. PMID:27053421
Inactivation of Hepatitis B Virus Replication in Cultured Cells and In Vivo with Engineered Transcription Activator-Like Effector Nucleases

PubMed Central

Bloom, Kristie; Ely, Abdullah; Mussolino, Claudio; Cathomen, Toni; Arbuthnot, Patrick

2013-01-01

Chronic hepatitis B virus (HBV) infection remains an important global health problem. Stability of the episomal covalently closed circular HBV DNA (cccDNA) is largely responsible for the modest curative efficacy of available therapy. Since licensed anti-HBV drugs have a post-transcriptional mechanism of action, disabling cccDNA is potentially of therapeutic benefit. To develop this approach, we engineered mutagenic transcription activator-like effector nucleases (TALENs) that target four HBV-specific sites within the viral genome. TALENs with cognate sequences in the S or C open-reading frames (ORFs) efficiently disrupted sequences at the intended sites and suppressed markers of viral replication. Following triple transfection of cultured HepG2.2.15 cells under mildly hypothermic conditions, the S TALEN caused targeted mutation in ~35% of cccDNA molecules. Markers of viral replication were also inhibited in vivo in a murine hydrodynamic injection model of HBV replication. HBV target sites within S and C ORFs of the injected HBV DNA were mutated without evidence of toxicity. These findings are the first to demonstrate a targeted nuclease-mediated disruption of HBV cccDNA. Efficacy in vivo also indicates that these engineered nucleases have potential for use in treatment of chronic HBV infection. PMID:23883864

Regulation of DNA Replication Timing on Human Chromosome by a Cell-Type Specific DNA Binding Protein SATB1

PubMed Central

Oda, Masako; Kanoh, Yutaka; Watanabe, Yoshihisa; Masai, Hisao

2012-01-01

Background Replication timing of metazoan DNA during S-phase may be determined by many factors including chromosome structures, nuclear positioning, patterns of histone modifications, and transcriptional activity. It may be determined by Mb-domain structures, termed as “replication domains”, and recent findings indicate that replication timing is under developmental and cell type-specific regulation. Methodology/Principal Findings We examined replication timing on the human 5q23/31 3.5-Mb segment in T cells and non-T cells. We used two independent methods to determine replication timing. One is quantification of nascent replicating DNA in cell cycle-fractionated stage-specific S phase populations. The other is FISH analyses of replication foci. Although the locations of early- and late-replicating domains were common between the two cell lines, the timing transition region (TTR) between early and late domains were offset by 200-kb. We show that Special AT-rich sequence Binding protein 1 (SATB1), specifically expressed in T-cells, binds to the early domain immediately adjacent to TTR and delays the replication timing of the TTR. Measurement of the chromosome copy number along the TTR during synchronized S phase suggests that the fork movement may be slowed down by SATB1. Conclusions Our results reveal a novel role of SATB1 in cell type-specific regulation of replication timing along the chromosome. PMID:22879953
Regulation of DNA replication timing on human chromosome by a cell-type specific DNA binding protein SATB1.

PubMed

Oda, Masako; Kanoh, Yutaka; Watanabe, Yoshihisa; Masai, Hisao

2012-01-01

Replication timing of metazoan DNA during S-phase may be determined by many factors including chromosome structures, nuclear positioning, patterns of histone modifications, and transcriptional activity. It may be determined by Mb-domain structures, termed as "replication domains", and recent findings indicate that replication timing is under developmental and cell type-specific regulation. We examined replication timing on the human 5q23/31 3.5-Mb segment in T cells and non-T cells. We used two independent methods to determine replication timing. One is quantification of nascent replicating DNA in cell cycle-fractionated stage-specific S phase populations. The other is FISH analyses of replication foci. Although the locations of early- and late-replicating domains were common between the two cell lines, the timing transition region (TTR) between early and late domains were offset by 200-kb. We show that Special AT-rich sequence Binding protein 1 (SATB1), specifically expressed in T-cells, binds to the early domain immediately adjacent to TTR and delays the replication timing of the TTR. Measurement of the chromosome copy number along the TTR during synchronized S phase suggests that the fork movement may be slowed down by SATB1. Our results reveal a novel role of SATB1 in cell type-specific regulation of replication timing along the chromosome.
BinQuasi: a peak detection method for ChIP-sequencing data with biological replicates.

PubMed

Goren, Emily; Liu, Peng; Wang, Chao; Wang, Chong

2018-04-19

ChIP-seq experiments that are aimed at detecting DNA-protein interactions require biological replication to draw inferential conclusions, however there is no current consensus on how to analyze ChIP-seq data with biological replicates. Very few methodologies exist for the joint analysis of replicated ChIP-seq data, with approaches ranging from combining the results of analyzing replicates individually to joint modeling of all replicates. Combining the results of individual replicates analyzed separately can lead to reduced peak classification performance compared to joint modeling. Currently available methods for joint analysis may fail to control the false discovery rate at the nominal level. We propose BinQuasi, a peak caller for replicated ChIP-seq data, that jointly models biological replicates using a generalized linear model framework and employs a one-sided quasi-likelihood ratio test to detect peaks. When applied to simulated data and real datasets, BinQuasi performs favorably compared to existing methods, including better control of false discovery rate than existing joint modeling approaches. BinQuasi offers a flexible approach to joint modeling of replicated ChIP-seq data which is preferable to combining the results of replicates analyzed individually. Source code is freely available for download at https://cran.r-project.org/package=BinQuasi, implemented in R. pliu@iastate.edu or egoren@iastate.edu. Supplementary material is available at Bioinformatics online.
Analysis of JC virus DNA replication using a quantitative and high-throughput assay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shin, Jong; Phelan, Paul J.; Chhum, Panharith

2014-11-15

Progressive Multifocal Leukoencephalopathy (PML) is caused by lytic replication of JC virus (JCV) in specific cells of the central nervous system. Like other polyomaviruses, JCV encodes a large T-antigen helicase needed for replication of the viral DNA. Here, we report the development of a luciferase-based, quantitative and high-throughput assay of JCV DNA replication in C33A cells, which, unlike the glial cell lines Hs 683 and U87, accumulate high levels of nuclear T-ag needed for robust replication. Using this assay, we investigated the requirement for different domains of T-ag, and for specific sequences within and flanking the viral origin, in JCVmore » DNA replication. Beyond providing validation of the assay, these studies revealed an important stimulatory role of the transcription factor NF1 in JCV DNA replication. Finally, we show that the assay can be used for inhibitor testing, highlighting its value for the identification of antiviral drugs targeting JCV DNA replication. - Highlights: • Development of a high-throughput screening assay for JCV DNA replication using C33A cells. • Evidence that T-ag fails to accumulate in the nuclei of established glioma cell lines. • Evidence that NF-1 directly promotes JCV DNA replication in C33A cells. • Proof-of-concept that the HTS assay can be used to identify pharmacological inhibitor of JCV DNA replication.« less
Microengineering of Metals and Ceramics: Part II: Special Replication Techniques, Automation and Properties; Volume 4: Advanced Micro & Nanosystems

NASA Astrophysics Data System (ADS)

Baltes, Henry; Brand, Oliver; Fedder, Gary K.; Hierold, Christofer; Korvink, Jan G.; Tabata, Osamu; Löhe, Detlef; Haußelt, Jürgen

2005-10-01

Microstructures, electronics, nanotechnology - these vast fields of research are growing together as the size gap narrows and many different materials are combined. Current research, engineering sucesses and newly commercialized products hint at the immense innovative potentials and future applications that open up once mankind controls shape and function from the atomic level right up to the visible world without any gaps. Continuing from the previous volume, authors from three major competence centres for microengineering here cover all aspects of specialized replication techniques and how to employ state-of-the-art technologies for testing and characterizing micro-scale components, and illustrate quality control aspects and strategies for automation of production procedures in view of future industrial production and commercialisation.
Stem cell identity and template DNA strand segregation.

PubMed

Tajbakhsh, Shahragim

2008-12-01

The quest for stem cell properties to distinguish their identity from that of committed daughters has led to a re-investigation of the notion that DNA strands are not equivalent, and 'immortal' DNA strands are retained in stem cells whereas newly replicated DNA strands segregate to the differentiating daughter cell during mitosis. Whether this process occurs only in stem cells, and also in all tissues, remains unclear. That individual chromosomes can be also partitioned non-randomly raises the question if this phenomenon is related to the immortal DNA hypothesis, and it underscores the need for high-resolution techniques to observe these events empirically. Although initially postulated as a mechanism to avoid DNA replication errors, alternative views including epigenetic regulation and sister chromatid silencing may provide insights into this process.
Class I Histone Deacetylase HDAC1 and WRN RECQ Helicase Contribute Additively to Protect Replication Forks upon Hydroxyurea-induced Arrest.

PubMed

Kehrli, Keffy; Phelps, Michael; Lazarchuk, Pavlo; Chen, Eleanor; Monnat, Ray; Sidorova, Julia M

2016-11-18

The WRN helicase/exonuclease is mutated in Werner syndrome of genomic instability and premature aging. WRN-depleted fibroblasts, although remaining largely viable, have a reduced capacity to maintain replication forks active during a transient hydroxyurea-induced arrest. A strand exchange protein, RAD51, is also required for replication fork maintenance, and here we show that recruitment of RAD51 to stalled forks is reduced in the absence of WRN. We performed a siRNA screen for genes that are required for viability of WRN-depleted cells after hydroxyurea treatment, and identified HDAC1, a member of the class I histone deacetylase family. One of the functions of HDAC1, which it performs together with a close homolog HDAC2, is deacetylation of new histone H4 deposited at replication forks. We show that HDAC1 depletion exacerbates defects in fork reactivation and progression after hydroxyurea treatment observed in WRN- or RAD51-deficient cells. The additive WRN, HDAC1 loss-of-function phenotype is also observed with a catalytic mutant of HDAC1; however, it does not correlate with changes in histone H4 deacetylation at replication forks. On the other hand, inhibition of histone deacetylation by an inhibitor specific to HDACs 1-3, CI-994, correlates with increased processing of newly synthesized DNA strands in hydroxyurea-stalled forks. WRN co-precipitates with HDAC1 and HDAC2. Taken together, our findings indicate that WRN interacts with HDACs 1 and 2 to facilitate activity of stalled replication forks under conditions of replication stress. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.
pUL34 binding near the human cytomegalovirus origin of lytic replication enhances DNA replication and viral growth.

PubMed

Slayton, Mark; Hossain, Tanvir; Biegalke, Bonita J

2018-05-01

The human cytomegalovirus (HCMV) UL34 gene encodes sequence-specific DNA-binding proteins (pUL34) which are required for viral replication. Interactions of pUL34 with DNA binding sites represses transcription of two viral immune evasion genes, US3 and US9. 12 additional predicted pUL34-binding sites are present in the HCMV genome (strain AD169) with three binding sites concentrated near the HCMV origin of lytic replication (oriLyt). We used ChIP-seq analysis of pUL34-DNA interactions to confirm that pUL34 binds to the oriLyt region during infection. Mutagenesis of the UL34-binding sites in an oriLyt-containing plasmid significantly reduced viral-mediated oriLyt-dependent DNA replication. Mutagenesis of these sites in the HCMV genome reduced the replication efficiencies of the resulting viruses. Protein-protein interaction analyses demonstrated that pUL34 interacts with the viral proteins IE2, UL44, and UL84, that are essential for viral DNA replication, suggesting that pUL34-DNA interactions in the oriLyt region are involved in the DNA replication cascade. Copyright © 2018 Elsevier Inc. All rights reserved.
The kinetoplast DNA of the Australian trypanosome, Trypanosoma copemani, shares features with Trypanosoma cruzi and Trypanosoma lewisi.

PubMed

Botero, Adriana; Kapeller, Irit; Cooper, Crystal; Clode, Peta L; Shlomai, Joseph; Thompson, R C Andrew

2018-05-17

Kinetoplast DNA (kDNA) is the mitochondrial genome of trypanosomatids. It consists of a few dozen maxicircles and several thousand minicircles, all catenated topologically to form a two-dimensional DNA network. Minicircles are heterogeneous in size and sequence among species. They present one or several conserved regions that contain three highly conserved sequence blocks. CSB-1 (10 bp sequence) and CSB-2 (8 bp sequence) present lower interspecies homology, while CSB-3 (12 bp sequence) or the Universal Minicircle Sequence is conserved within most trypanosomatids. The Universal Minicircle Sequence is located at the replication origin of the minicircles, and is the binding site for the UMS binding protein, a protein involved in trypanosomatid survival and virulence. Here, we describe the structure and organisation of the kDNA of Trypanosoma copemani, a parasite that has been shown to infect mammalian cells and has been associated with the drastic decline of the endangered Australian marsupial, the woylie (Bettongia penicillata). Deep genomic sequencing showed that T. copemani presents two classes of minicircles that share sequence identity and organisation in the conserved sequence blocks with those of Trypanosoma cruzi and Trypanosoma lewisi. A 19,257 bp partial region of the maxicircle of T. copemani that contained the entire coding region was obtained. Comparative analysis of the T. copemani entire maxicircle coding region with the coding regions of T. cruzi and T. lewisi showed they share 71.05% and 71.28% identity, respectively. The shared features in the maxicircle/minicircle organisation and sequence between T. copemani and T. cruzi/T. lewisi suggest similarities in their process of kDNA replication, and are of significance in understanding the evolution of Australian trypanosomes. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.
Characterization and Construction of Functional cDNA Clones of Pariacoto Virus, the First Alphanodavirus Isolated outside Australasia

PubMed Central

Johnson, Karyn N.; Zeddam, Jean-Louis; Ball, L. Andrew

2000-01-01

Pariacoto virus (PaV) was recently isolated in Peru from the Southern armyworm (Spodoptera eridania). PaV particles are isometric, nonenveloped, and about 30 nm in diameter. The virus has a bipartite RNA genome and a single major capsid protein with a molecular mass of 39.0 kDa, features that support its classification as a Nodavirus. As such, PaV is the first Alphanodavirus to have been isolated from outside Australasia. Here we report that PaV replicates in wax moth larvae and that PaV genomic RNAs replicate when transfected into cultured baby hamster kidney cells. The complete nucleotide sequences of both segments of the bipartite RNA genome were determined. The larger genome segment, RNA1, is 3,011 nucleotides long and contains a 973-amino-acid open reading frame (ORF) encoding protein A, the viral contribution to the RNA replicase. During replication, a 414-nucleotide long subgenomic RNA (RNA3) is synthesized which is coterminal with the 3′ end of RNA1. RNA3 contains a small ORF which could encode a protein of 90 amino acids similar to the B2 protein of other alphanodaviruses. RNA2 contains 1,311 nucleotides and encodes the 401 amino acids of the capsid protein precursor α. The amino acid sequences of the PaV capsid protein and the replicase subunit share 41 and 26% identity with homologous proteins of Flock house virus, the best characterized of the alphanodaviruses. These and other sequence comparisons indicate that PaV is evolutionarily the most distant of the alphanodaviruses described to date, consistent with its novel geographic origin. Although the PaV capsid precursor is cleaved into the two mature capsid proteins β and γ, the amino acid sequence at the cleavage site, which is Asn/Ala in all other alphanodaviruses, is Asn/Ser in PaV. To facilitate the investigation of PaV replication in cultured cells, we constructed plasmids that transcribed full-length PaV RNAs with authentic 5′ and 3′ termini. Transcription of these plasmids in cells recreated the replication of PaV RNA1 and RNA2, synthesis of subgenomic RNA3, and translation of viral proteins A and α. PMID:10799587
Characterization and construction of functional cDNA clones of Pariacoto virus, the first Alphanodavirus isolated outside Australasia.

PubMed

Johnson, K N; Zeddam, J L; Ball, L A

2000-06-01

Pariacoto virus (PaV) was recently isolated in Peru from the Southern armyworm (Spodoptera eridania). PaV particles are isometric, nonenveloped, and about 30 nm in diameter. The virus has a bipartite RNA genome and a single major capsid protein with a molecular mass of 39.0 kDa, features that support its classification as a Nodavirus. As such, PaV is the first Alphanodavirus to have been isolated from outside Australasia. Here we report that PaV replicates in wax moth larvae and that PaV genomic RNAs replicate when transfected into cultured baby hamster kidney cells. The complete nucleotide sequences of both segments of the bipartite RNA genome were determined. The larger genome segment, RNA1, is 3,011 nucleotides long and contains a 973-amino-acid open reading frame (ORF) encoding protein A, the viral contribution to the RNA replicase. During replication, a 414-nucleotide long subgenomic RNA (RNA3) is synthesized which is coterminal with the 3' end of RNA1. RNA3 contains a small ORF which could encode a protein of 90 amino acids similar to the B2 protein of other alphanodaviruses. RNA2 contains 1,311 nucleotides and encodes the 401 amino acids of the capsid protein precursor alpha. The amino acid sequences of the PaV capsid protein and the replicase subunit share 41 and 26% identity with homologous proteins of Flock house virus, the best characterized of the alphanodaviruses. These and other sequence comparisons indicate that PaV is evolutionarily the most distant of the alphanodaviruses described to date, consistent with its novel geographic origin. Although the PaV capsid precursor is cleaved into the two mature capsid proteins beta and gamma, the amino acid sequence at the cleavage site, which is Asn/Ala in all other alphanodaviruses, is Asn/Ser in PaV. To facilitate the investigation of PaV replication in cultured cells, we constructed plasmids that transcribed full-length PaV RNAs with authentic 5' and 3' termini. Transcription of these plasmids in cells recreated the replication of PaV RNA1 and RNA2, synthesis of subgenomic RNA3, and translation of viral proteins A and alpha.
Sequence characterization of heat shock protein gene of Cyclospora cayetanensis isolates from Nepal, Mexico, and Peru.

PubMed

Sulaiman, Irshad M; Torres, Patricia; Simpson, Steven; Kerdahi, Khalil; Ortega, Ynes

2013-04-01

We have described the development of a 2-step nested PCR protocol based on the characterization of the 70-kDa heat shock protein (HSP70) gene for rapid detection of the human-pathogenic Cyclospora cayetanensis parasite. We tested and validated these newly designed primer sets by PCR amplification followed by nucleotide sequencing of PCR-amplified HSP70 fragments belonging to 16 human C. cayetanensis isolates from 3 different endemic regions that include Nepal, Mexico, and Peru. No genetic polymorphism was observed among the isolates at the characterized regions of the HSP70 locus. This newly developed HSP70 gene-based nested PCR protocol provides another useful genetic marker for the rapid detection of C. cayetanensis in the future.
Biopanning of polypeptides binding to bovine ephemeral fever virus G1 protein from phage display peptide library.

PubMed

Hou, Peili; Zhao, Guimin; He, Chengqiang; Wang, Hongmei; He, Hongbin

2018-01-04

The bovine ephemeral fever virus (BEFV) glycoprotein neutralization site 1 (also referred as G 1 protein), is a critical protein responsible for virus infectivity and eliciting immune-protection, however, binding peptides of BEFV G 1 protein are still unclear. Thus, the aim of the present study was to screen specific polypeptides, which bind BEFV G 1 protein with high-affinity and inhibit BEFV replication. The purified BEFV G 1 was coated and then reacted with the M13-based Ph.D.-7 phage random display library. The peptides for target binding were automated sequenced after four rounds of enrichment biopanning. The amino acid sequences of polypeptide displayed on positive clones were deduced and the affinity of positive polypeptides with BEFV G 1 was assayed by ELISA. Then the roles of specific G 1 -binding peptides in the context of BEFV infection were analyzed. The results showed that 27 specific peptide ligands displaying 11 different amino acid sequences were obtained, and the T18 and T25 clone had a higher affinity to G 1 protein than the other clones. Then their antiviral roles of two phage clones (T25 and T18) showed that both phage polypeptide T25 and T18 exerted inhibition on BEFV replication compared to control group. Moreover, synthetic peptide based on T18 (HSIRYDF) and T25 (YSLRSDY) alone or combined use on BEFV replication showed that the synthetic peptides could effectively inhibit the formation of cytopathic plaque and significantly inhibit BEFV RNA replication in a dose-dependent manner. Two antiviral peptide ligands binding to bovine ephemeral fever virus G 1 protein from phage display peptide library were identified, which may provide a potential research tool for diagnostic reagents and novel antiviral agents.
The Effect of Joint Control Training on the Acquisition and Durability of a Sequencing Task

ERIC Educational Resources Information Center

DeGraaf, Allison; Schlinger, Henry D., Jr.

2012-01-01

Gutierrez (2006) experimentally demonstrated the effects of joint control and particularly the role of response mediation in the sequencing behavior of adults using an unfamiliar language. The purpose of the current study was to replicate and extend the procedures used by Gutierrez by comparing the effects of joint control training with the…
Random sampling causes the low reproducibility of rare eukaryotic OTUs in Illumina COI metabarcoding.

PubMed

Leray, Matthieu; Knowlton, Nancy

2017-01-01

DNA metabarcoding, the PCR-based profiling of natural communities, is becoming the method of choice for biodiversity monitoring because it circumvents some of the limitations inherent to traditional ecological surveys. However, potential sources of bias that can affect the reproducibility of this method remain to be quantified. The interpretation of differences in patterns of sequence abundance and the ecological relevance of rare sequences remain particularly uncertain. Here we used one artificial mock community to explore the significance of abundance patterns and disentangle the effects of two potential biases on data reproducibility: indexed PCR primers and random sampling during Illumina MiSeq sequencing. We amplified a short fragment of the mitochondrial Cytochrome c Oxidase Subunit I (COI) for a single mock sample containing equimolar amounts of total genomic DNA from 34 marine invertebrates belonging to six phyla. We used seven indexed broad-range primers and sequenced the resulting library on two consecutive Illumina MiSeq runs. The total number of Operational Taxonomic Units (OTUs) was ∼4 times higher than expected based on the composition of the mock sample. Moreover, the total number of reads for the 34 components of the mock sample differed by up to three orders of magnitude. However, 79 out of 86 of the unexpected OTUs were represented by <10 sequences that did not appear consistently across replicates. Our data suggest that random sampling of rare OTUs (e.g., small associated fauna such as parasites) accounted for most of variation in OTU presence-absence, whereas biases associated with indexed PCRs accounted for a larger amount of variation in relative abundance patterns. These results suggest that random sampling during sequencing leads to the low reproducibility of rare OTUs. We suggest that the strategy for handling rare OTUs should depend on the objectives of the study. Systematic removal of rare OTUs may avoid inflating diversity based on common β descriptors but will exclude positive records of taxa that are functionally important. Our results further reinforce the need for technical replicates (parallel PCR and sequencing from the same sample) in metabarcoding experimental designs. Data reproducibility should be determined empirically as it will depend upon the sequencing depth, the type of sample, the sequence analysis pipeline, and the number of replicates. Moreover, estimating relative biomasses or abundances based on read counts remains elusive at the OTU level.
Replication, checkpoint suppression and structure of centromeric DNA

PubMed Central

Romeo, Francesco; Costanzo, Vincenzo

2016-01-01

ABSTRACT Human centromeres contain large amounts of repetitive DNA sequences known as α satellite DNA, which can be difficult to replicate and whose functional role is unclear. Recently, we have characterized protein composition, structural organization and checkpoint response to stalled replication forks of centromeric chromatin reconstituted in Xenopus laevis egg extract. We showed that centromeric DNA has high affinity for SMC2-4 subunits of condensins and for CENP-A, it is enriched for DNA repair factors and suppresses the ATR checkpoint to ensure its efficient replication. We also showed that centromeric chromatin forms condensins enriched and topologically constrained DNA loops, which likely contribute to the overall structure of the centromere. These findings have important implications on how chromosomes are organized and genome stability is maintained in mammalian cells. PMID:27893298
Construction of a subgenomic CV-B3 replicon expressing emerald green fluorescent protein to assess viral replication of a cardiotropic enterovirus strain in cultured human cells.

PubMed

Wehbe, Michel; Huguenin, Antoine; Leveque, Nicolas; Semler, Bert L; Hamze, Monzer; Andreoletti, Laurent; Bouin, Alexis

2016-04-01

Coxsackieviruses B (CV-B) (Picornaviridae) are a common infectious cause of acute myocarditis in children and young adults, a disease, which is a precursor to 10-20% of chronic myocarditis and dilated cardiomyopathy (DCM) cases. The mechanisms involved in the disease progression from acute to chronic myocarditis phase and toward the DCM clinical stage are not fully understood but are influenced by both viral and host factors. Subgenomic replicons of CV-B can be used to assess viral replication mechanisms in human cardiac cells and evaluate the effects of potential antiviral drugs on viral replication activities. Our objectives were to generate a reporter replicon from a cardiotropic prototype CV-B3/28 strain and to characterize its replication properties into human cardiac primary cells. To obtain this replicon, a cDNA plasmid containing the full CV-B3/28 genome flanked by a hammerhead ribozyme sequence and an MluI restriction site was generated and used as a platform for the insertion of sequences encoding emerald green fluorescent protein (EmGFP) in place of those encoding VP3. In vitro transcribed RNA from this plasmid was transfected into HeLa cells and human primary cardiac cells and was able to produce EmGFP and VP1-containing polypeptides. Moreover, non-structural protein biological activity was assessed by the specific cleavage of eIF4G1 by viral 2A(pro). Viral RNA replication was indirectly demonstrated by inhibition assays, fluoxetine was added to cell culture and prevented the EmGFP synthesis. Our results indicated that the EmGFP CV-B3 replicon was able to replicate and translate as well as the CV-B3/28 prototype strain. Our EmGFP CV-B3 replicon will be a valuable tool to readily investigate CV-B3 replication activities in human target cell models. Copyright © 2016 Elsevier B.V. All rights reserved.
Differential gene expression in the siphonophore Nanomia bijuga (Cnidaria) assessed with multiple next-generation sequencing workflows.

PubMed

Siebert, Stefan; Robinson, Mark D; Tintori, Sophia C; Goetz, Freya; Helm, Rebecca R; Smith, Stephen A; Shaner, Nathan; Haddock, Steven H D; Dunn, Casey W

2011-01-01

We investigated differential gene expression between functionally specialized feeding polyps and swimming medusae in the siphonophore Nanomia bijuga (Cnidaria) with a hybrid long-read/short-read sequencing strategy. We assembled a set of partial gene reference sequences from long-read data (Roche 454), and generated short-read sequences from replicated tissue samples that were mapped to the references to quantify expression. We collected and compared expression data with three short-read expression workflows that differ in sample preparation, sequencing technology, and mapping tools. These workflows were Illumina mRNA-Seq, which generates sequence reads from random locations along each transcript, and two tag-based approaches, SOLiD SAGE and Helicos DGE, which generate reads from particular tag sites. Differences in expression results across workflows were mostly due to the differential impact of missing data in the partial reference sequences. When all 454-derived gene reference sequences were considered, Illumina mRNA-Seq detected more than twice as many differentially expressed (DE) reference sequences as the tag-based workflows. This discrepancy was largely due to missing tag sites in the partial reference that led to false negatives in the tag-based workflows. When only the subset of reference sequences that unambiguously have tag sites was considered, we found broad congruence across workflows, and they all identified a similar set of DE sequences. Our results are promising in several regards for gene expression studies in non-model organisms. First, we demonstrate that a hybrid long-read/short-read sequencing strategy is an effective way to collect gene expression data when an annotated genome sequence is not available. Second, our replicated sampling indicates that expression profiles are highly consistent across field-collected animals in this case. Third, the impacts of partial reference sequences on the ability to detect DE can be mitigated through workflow choice and deeper reference sequencing.
Differential Gene Expression in the Siphonophore Nanomia bijuga (Cnidaria) Assessed with Multiple Next-Generation Sequencing Workflows

PubMed Central

Siebert, Stefan; Robinson, Mark D.; Tintori, Sophia C.; Goetz, Freya; Helm, Rebecca R.; Smith, Stephen A.; Shaner, Nathan; Haddock, Steven H. D.; Dunn, Casey W.

2011-01-01

We investigated differential gene expression between functionally specialized feeding polyps and swimming medusae in the siphonophore Nanomia bijuga (Cnidaria) with a hybrid long-read/short-read sequencing strategy. We assembled a set of partial gene reference sequences from long-read data (Roche 454), and generated short-read sequences from replicated tissue samples that were mapped to the references to quantify expression. We collected and compared expression data with three short-read expression workflows that differ in sample preparation, sequencing technology, and mapping tools. These workflows were Illumina mRNA-Seq, which generates sequence reads from random locations along each transcript, and two tag-based approaches, SOLiD SAGE and Helicos DGE, which generate reads from particular tag sites. Differences in expression results across workflows were mostly due to the differential impact of missing data in the partial reference sequences. When all 454-derived gene reference sequences were considered, Illumina mRNA-Seq detected more than twice as many differentially expressed (DE) reference sequences as the tag-based workflows. This discrepancy was largely due to missing tag sites in the partial reference that led to false negatives in the tag-based workflows. When only the subset of reference sequences that unambiguously have tag sites was considered, we found broad congruence across workflows, and they all identified a similar set of DE sequences. Our results are promising in several regards for gene expression studies in non-model organisms. First, we demonstrate that a hybrid long-read/short-read sequencing strategy is an effective way to collect gene expression data when an annotated genome sequence is not available. Second, our replicated sampling indicates that expression profiles are highly consistent across field-collected animals in this case. Third, the impacts of partial reference sequences on the ability to detect DE can be mitigated through workflow choice and deeper reference sequencing. PMID:21829563
A comparison of RNA with DNA in template-directed synthesis

NASA Technical Reports Server (NTRS)

Zielinski, M.; Kozlov, I. A.; Orgel, L. E.; Bada, J. L. (Principal Investigator)

2000-01-01

Nonenzymatic template-directed copying of RNA sequences rich in cytidylic acid using nucleoside 5'-(2-methylimidazol-1-yl phosphates) as substrates is substantially more efficient than the copying of corresponding DNA sequences. However, many sequences cannot be copied, and the prospect of replication in this system is remote, even for RNA. Surprisingly, wobble-pairing leads to much more efficient incorporation of G opposite U on RNA templates than of G opposite T on DNA templates.

A 5′ Noncoding Exon Containing Engineered Intron Enhances Transgene Expression from Recombinant AAV Vectors in vivo

PubMed Central

Lu, Jiamiao; Williams, James A.; Luke, Jeremy; Zhang, Feijie; Chu, Kirk; Kay, Mark A.

2017-01-01

We previously developed a mini-intronic plasmid (MIP) expression system in which the essential bacterial elements for plasmid replication and selection are placed within an engineered intron contained within a universal 5′ UTR noncoding exon. Like minicircle DNA plasmids (devoid of bacterial backbone sequences), MIP plasmids overcome transcriptional silencing of the transgene. However, in addition MIP plasmids increase transgene expression by 2 and often >10 times higher than minicircle vectors in vivo and in vitro. Based on these findings, we examined the effects of the MIP intronic sequences in a recombinant adeno-associated virus (AAV) vector system. Recombinant AAV vectors containing an intron with a bacterial replication origin and bacterial selectable marker increased transgene expression by 40 to 100 times in vivo when compared with conventional AAV vectors. Therefore, inclusion of this noncoding exon/intron sequence upstream of the coding region can substantially enhance AAV-mediated gene expression in vivo. PMID:27903072
Plasmid origin of replication of herpesvirus papio: DNA sequence and enhancer function.

PubMed Central

Loeb, D D; Sung, N S; Pesano, R L; Sexton, C J; Hutchison, C; Pagano, J S

1990-01-01

Herpesvirus papio (HVP) is a lymphotropic virus of baboons which is related to Epstein-Barr virus (EBV) and produces latent infection. The nucleotide sequence of the 5,775-base-pair (bp) EcoRI K fragment of HVP, which has previously been shown to confer the ability to replicate autonomously, has been determined. Within this DNA fragment is a region which bears structural and sequence similarity to the ori-P region of EBV. The HVP ori-P region has a 10- by 26-bp tandem array which is related to the 20- by 30-bp tandem array from the EBV ori-P region. In HVP there is an intervening region of 764 bp followed by five partial copies of the 26-bp monomer. Both the EBV and HVP 3' regions have the potential to form dyad structures which, however, differ in arrangement. We also demonstrate that a transcriptional enhancer which requires transactivation by a virus-encoded factor is present in the HVP ori-P. Images PMID:2159548
Evolutionary dynamics on networks of selectively neutral genotypes: effects of topology and sequence stability.

PubMed

Aguirre, Jacobo; Buldú, Javier M; Manrubia, Susanna C

2009-12-01

Networks of selectively neutral genotypes underlie the evolution of populations of replicators in constant environments. Previous theoretical analysis predicted that such populations will evolve toward highly connected regions of the genome space. We first study the evolution of populations of replicators on simple networks and quantify how the transient time to equilibrium depends on the initial distribution of sequences on the neutral network, on the topological properties of the latter, and on the mutation rate. Second, network neutrality is broken through the introduction of an energy for each sequence. This allows to study the competition between two features (neutrality and energetic stability) relevant for survival and subjected to different selective pressures. In cases where the two features are negatively correlated, the population experiences sudden migrations in the genome space for values of the relevant parameters that we calculate. The numerical study of larger networks indicates that the qualitative behavior to be expected in more realistic cases is already seen in representative examples of small networks.
Evolutionary dynamics on networks of selectively neutral genotypes: Effects of topology and sequence stability

NASA Astrophysics Data System (ADS)

Aguirre, Jacobo; Buldú, Javier M.; Manrubia, Susanna C.

2009-12-01

Networks of selectively neutral genotypes underlie the evolution of populations of replicators in constant environments. Previous theoretical analysis predicted that such populations will evolve toward highly connected regions of the genome space. We first study the evolution of populations of replicators on simple networks and quantify how the transient time to equilibrium depends on the initial distribution of sequences on the neutral network, on the topological properties of the latter, and on the mutation rate. Second, network neutrality is broken through the introduction of an energy for each sequence. This allows to study the competition between two features (neutrality and energetic stability) relevant for survival and subjected to different selective pressures. In cases where the two features are negatively correlated, the population experiences sudden migrations in the genome space for values of the relevant parameters that we calculate. The numerical study of larger networks indicates that the qualitative behavior to be expected in more realistic cases is already seen in representative examples of small networks.
The mitochondrial genome of Pocillopora (Cnidaria: Scleractinia) contains two variable regions: the putative D-loop and a novel ORF of unknown function.

PubMed

Flot, Jean-François; Tillier, Simon

2007-10-15

The complete mitochondrial genomes of two individuals attributed to different morphospecies of the scleractinian coral genus Pocillopora have been sequenced. Both genomes, respectively 17,415 and 17,422 nt long, share the presence of a previously undescribed ORF encoding a putative protein made up of 302 amino acids and of unknown function. Surprisingly, this ORF turns out to be the second most variable region of the mitochondrial genome (1% nucleotide sequence difference between the two individuals) after the putative control region (1.5% sequence difference). Except for the presence of this ORF and for the location of the putative control region, the mitochondrial genome of Pocillopora is organized in a fashion similar to the other scleractinian coral genomes published to date. For the first time in a cnidarian, a putative second origin of replication is described based on its secondary structure similar to the stem-loop structure of O(L), the origin of L-strand replication in vertebrates.
A large inversion in the linear chromosome of Streptomyces griseus caused by replicative transposition of a new Tn3 family transposon.

PubMed

Murata, M; Uchida, T; Yang, Y; Lezhava, A; Kinashi, H

2011-04-01

We have comprehensively analyzed the linear chromosomes of Streptomyces griseus mutants constructed and kept in our laboratory. During this study, macrorestriction analysis of AseI and DraI fragments of mutant 402-2 suggested a large chromosomal inversion. The junctions of chromosomal inversion were cloned and sequenced and compared with the corresponding target sequences in the parent strain 2247. Consequently, a transposon-involved mechanism was revealed. Namely, a transposon originally located at the left target site was replicatively transposed to the right target site in an inverted direction, which generated a second copy and at the same time caused a 2.5-Mb chromosomal inversion. The involved transposon named TnSGR was grouped into a new subfamily of the resolvase-encoding Tn3 family transposons based on its gene organization. At the end, terminal diversity of S. griseus chromosomes is discussed by comparing the sequences of strains 2247 and IFO13350.
The virome of the arbuscular mycorrhizal fungus Gigaspora margarita reveals the first report of DNA fragments corresponding to replicating non-retroviral RNA viruses in fungi.

PubMed

Turina, Massimo; Ghignone, Stefano; Astolfi, Nausicaa; Silvestri, Alessandro; Bonfante, Paola; Lanfranco, Luisa

2018-02-02

Arbuscular Mycorrhizal Fungi (AMF) are key components of the plant microbiota. AMF genetic complexity is increased by the presence of endobacteria, which live inside many species. A further component of such complexity is the virome associated to AMF, whose knowledge is still very limited. Here, by exploiting transcriptomic data we describe the virome of Gigaspora margarita. A BLAST search for viral RNA-dependent RNA polymerases sequences allowed the identification of four mitoviruses, one Ourmia-like narnavirus, one Giardia-like virus, and two sequences related to Fusarium graminearum mycoviruses. Northern blot and RT-PCR confirmed the authenticity of all the sequences with the exception of the F. graminearum-related ones. All the mitoviruses are replicative and functional since both positive strand and negative strand RNA are present. The abundance of the viral RNA molecules is not regulated by the presence or absence of Candidatus Glomeribacter gigasporarum, the endobacterium hosted by G. margarita, with the exception of the Ourmia-like sequence which is absent in bacteria-cured spores. In addition, we report, for the first time, DNA fragments corresponding to mitovirus sequences associated to the presence of viral RNA. These sequences are not integrated in the mitochondrial DNA and preliminary evidence seems to exclude integration in the nuclear genome. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruggles, Kelly V.; Tang, Zuojian; Wang, Xuya

Improvements in mass spectrometry (MS)-based peptide sequencing provide a new opportunity to determine whether polymorphisms, mutations and splice variants identified in cancer cells are translated. Herein we therefore describe a proteogenomic data integration tool (QUILTS) and illustrate its application to whole genome, transcriptome and global MS peptide sequence datasets generated from a pair of luminal and basal-like breast cancer patient derived xenografts (PDX). The sensitivity of proteogenomic analysis for singe nucleotide variant (SNV) expression and novel splice junction (NSJ) detection was probed using multiple MS/MS process replicates. Despite over thirty sample replicates, only about 10% of all SNV (somatic andmore » germline) were detected by both DNA and RNA sequencing were observed as peptides. An even smaller proportion of peptides corresponding to NSJ observed by RNA sequencing were detected (<0.1%). Peptides mapping to DNA-detected SNV without a detectable mRNA transcript were also observed demonstrating the transcriptome coverage was also incomplete (~80%). In contrast to germ-line variants, somatic variants were less likely to be detected at the peptide level in the basal-like tumor than the luminal tumor raising the possibility of differential translation or protein degradation effects. In conclusion, the QUILTS program integrates DNA, RNA and peptide sequencing to assess the degree to which somatic mutations are translated and therefore biologically active. By identifying gaps in sequence coverage QUILTS benchmarks current technology and assesses progress towards whole cancer proteome and transcriptome analysis.« less
How behavioral economics can help to avoid 'The last mile problem' in whole genome sequencing.

PubMed

Blumenthal-Barby, Jennifer S; McGuire, Amy L; Green, Robert C; Ubel, Peter A

2015-01-01

Failure to consider lessons from behavioral economics in the case of whole genome sequencing may cause us to run into the 'last mile problem' - the failure to integrate newly developed technology, on which billions of dollars have been invested, into society in a way that improves human behavior and decision-making.
Evaluation of the utility of the new rainbow trout genome assembly for analyzing RNA-seq data from stress response experiments

USDA-ARS?s Scientific Manuscript database

The newly released rainbow trout genome assembly in NCBI RefSeq has greatly expanded our abilities for analyzing rainbow trout sequencing data. In this poster, we evaluate the utility of this genome assembly for analyzing RNA sequencing (RNA-seq) data of rainbow trout responses to various stressors,...
Draft Genome Sequence of Lactobacillus salivarius L28 Isolated from Ground Beef.

PubMed

Ayala, Diana I; Cook, Peter W; Campos, David L; Brashears, Mindy M; den Bakker, Henk; Nightingale, Kendra K

2017-09-28

In this report, we describe the draft genome sequence of a newly discovered probiotic strain, Lactobacillus salivarius L28. L. salivarius L28 demonstrates antagonistic effects against human foodborne pathogens, including Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes , in coculture experiments and food matrices. Copyright © 2017 Ayala et al.
Draft Genome Sequence of Lactobacillus salivarius L28 Isolated from Ground Beef

PubMed Central

Ayala, Diana I.; Cook, Peter W.; Campos, David L.; Brashears, Mindy M.; den Bakker, Henk

2017-01-01

ABSTRACT In this report, we describe the draft genome sequence of a newly discovered probiotic strain, Lactobacillus salivarius L28. L. salivarius L28 demonstrates antagonistic effects against human foodborne pathogens, including Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes, in coculture experiments and food matrices. PMID:28963206
Local neutral networks help maintain inaccurately replicating ribozymes.

PubMed

Szilágyi, András; Kun, Ádám; Szathmáry, Eörs

2014-01-01

The error threshold of replication limits the selectively maintainable genome size against recurrent deleterious mutations for most fitness landscapes. In the context of RNA replication a distinction between the genotypic and the phenotypic error threshold has been made; where the latter concerns the maintenance of secondary structure rather than sequence. RNA secondary structure is treated as a proxy for function. The phenotypic error threshold allows higher per digit mutation rates than its genotypic counterpart, and is known to increase with the frequency of neutral mutations in sequence space. Here we show that the degree of neutrality, i.e. the frequency of nearest-neighbour (one-step) neutral mutants is a remarkably accurate proxy for the overall frequency of such mutants in an experimentally verifiable formula for the phenotypic error threshold; this we achieve by the full numerical solution for the concentration of all sequences in mutation-selection balance up to length 16. We reinforce our previous result that currently known ribozymes could be selectively maintained by the accuracy known from the best available polymerase ribozymes. Furthermore, we show that in silico stabilizing selection can increase the mutational robustness of ribozymes due to the fact that they were produced by artificial directional selection in the first place. Our finding offers a better understanding of the error threshold and provides further insight into the plausibility of an ancient RNA world.
Characterization of a Theta-Type Plasmid from Lactobacillus sakei: a Potential Basis for Low-Copy-Number Vectors in Lactobacilli

PubMed Central

Alpert, Carl-Alfred; Crutz-Le Coq, Anne-Marie; Malleret, Christine; Zagorec, Monique

2003-01-01

The complete nucleotide sequence of the 13-kb plasmid pRV500, isolated from Lactobacillus sakei RV332, was determined. Sequence analysis enabled the identification of genes coding for a putative type I restriction-modification system, two genes coding for putative recombinases of the integrase family, and a region likely involved in replication. The structural features of this region, comprising a putative ori segment containing 11- and 22-bp repeats and a repA gene coding for a putative initiator protein, indicated that pRV500 belongs to the pUCL287 subfamily of theta-type replicons. A 3.7-kb fragment encompassing this region was fused to an Escherichia coli replicon to produce the shuttle vector pRV566 and was observed to be functional in L. sakei for plasmid replication. The L. sakei replicon alone could not support replication in E. coli. Plasmid pRV500 and its derivative pRV566 were determined to be at very low copy numbers in L. sakei. pRV566 was maintained at a reasonable rate over 20 generations in several lactobacilli, such as Lactobacillus curvatus, Lactobacillus casei, and Lactobacillus plantarum, in addition to L. sakei, making it an interesting basis for developing vectors. Sequence relationships with other plasmids are described and discussed. PMID:12957947
Replication of a low-pathogenic avian influenza virus is enhanced by chicken ubiquitin-specific protease 18.

PubMed

Tanikawa, Taichiro; Uchida, Yuko; Saito, Takehiko

2017-09-01

Previous research revealed the induction of chicken USP18 (chUSP18) in the lungs of chickens infected with highly pathogenic avian influenza viruses (HPAIVs). This activity was correlated with the degree of pathogenicity of the viruses to chickens. As mammalian ubiquitin-specific protease (USP18) is known to remove type I interferon (IFN I)-inducible ubiquitin-like molecules from conjugated proteins and block IFN I signalling, we explored the function of the chicken homologue of USP18 during avian influenza virus infection. With this aim, we cloned chUSP18 from cultured chicken cells and revealed that the putative chUSP18 ORF comprises 1137 bp. Comparative analysis of the predicted aa sequence of chUSP18 with those of human and mouse USP18 revealed relatively high sequence similarity among the sequences, including domains specific for the ubiquitin-specific processing protease family. Furthermore, we found that chUSP18 expression was induced by chicken IFN I, as observed for mammalian USP18. Experiments based on chUSP18 over-expression and depletion demonstrated that chUSP18 significantly enhanced the replication of a low-pathogenic avian influenza virus (LPAIV), but not an HPAIV. Our findings suggest that chUSP18, being similar to mammalian USP18, acts as a pro-viral factor during LPAIV replication in vitro.
Limited copy number - high resolution melting (LCN-HRM) enables the detection and identification by sequencing of low level mutations in cancer biopsies

PubMed Central

Do, Hongdo; Dobrovic, Alexander

2009-01-01

Background Mutation detection in clinical tumour samples is challenging when the proportion of tumour cells, and thus mutant alleles, is low. The limited sensitivity of conventional sequencing necessitates the adoption of more sensitive approaches. High resolution melting (HRM) is more sensitive than sequencing but identification of the mutation is desirable, particularly when it is important to discriminate false positives due to PCR errors or template degradation from true mutations. We thus developed limited copy number - high resolution melting (LCN-HRM) which applies limiting dilution to HRM. Multiple replicate reactions with a limited number of target sequences per reaction allow low level mutations to be detected. The dilutions used (based on Ct values) are chosen such that mutations, if present, can be detected by the direct sequencing of amplicons with aberrant melting patterns. Results Using cell lines heterozygous for mutations, we found that the mutations were not readily detected when they comprised 10% of total alleles (20% tumour cells) by sequencing, whereas they were readily detectable at 5% total alleles by standard HRM. LCN-HRM allowed these mutations to be identified by direct sequencing of those positive reactions. LCN-HRM was then used to review formalin-fixed paraffin-embedded (FFPE) clinical samples showing discordant findings between sequencing and HRM for KRAS exon 2 and EGFR exons 19 and 21. Both true mutations present at low levels and sequence changes due to artefacts were detected by LCN-HRM. The use of high fidelity polymerases showed that the majority of the artefacts were derived from the damaged template rather than replication errors during amplification. Conclusion LCN-HRM bridges the sensitivity gap between HRM and sequencing and is effective in distinguishing between artefacts and true mutations. PMID:19811662
Limited copy number-high resolution melting (LCN-HRM) enables the detection and identification by sequencing of low level mutations in cancer biopsies.

PubMed

Do, Hongdo; Dobrovic, Alexander

2009-10-08

Mutation detection in clinical tumour samples is challenging when the proportion of tumour cells, and thus mutant alleles, is low. The limited sensitivity of conventional sequencing necessitates the adoption of more sensitive approaches. High resolution melting (HRM) is more sensitive than sequencing but identification of the mutation is desirable, particularly when it is important to discriminate false positives due to PCR errors or template degradation from true mutations.We thus developed limited copy number - high resolution melting (LCN-HRM) which applies limiting dilution to HRM. Multiple replicate reactions with a limited number of target sequences per reaction allow low level mutations to be detected. The dilutions used (based on Ct values) are chosen such that mutations, if present, can be detected by the direct sequencing of amplicons with aberrant melting patterns. Using cell lines heterozygous for mutations, we found that the mutations were not readily detected when they comprised 10% of total alleles (20% tumour cells) by sequencing, whereas they were readily detectable at 5% total alleles by standard HRM. LCN-HRM allowed these mutations to be identified by direct sequencing of those positive reactions.LCN-HRM was then used to review formalin-fixed paraffin-embedded (FFPE) clinical samples showing discordant findings between sequencing and HRM for KRAS exon 2 and EGFR exons 19 and 21. Both true mutations present at low levels and sequence changes due to artefacts were detected by LCN-HRM. The use of high fidelity polymerases showed that the majority of the artefacts were derived from the damaged template rather than replication errors during amplification. LCN-HRM bridges the sensitivity gap between HRM and sequencing and is effective in distinguishing between artefacts and true mutations.
Comparison of Constitutional and Replication Stress-Induced Genome Structural Variation by SNP Array and Mate-Pair Sequencing

PubMed Central

Arlt, Martin F.; Ozdemir, Alev Cagla; Birkeland, Shanda R.; Lyons, Robert H.; Glover, Thomas W.; Wilson, Thomas E.

2011-01-01

Copy-number variants (CNVs) are a major source of genetic variation in human health and disease. Previous studies have implicated replication stress as a causative factor in CNV formation. However, existing data are technically limited in the quality of comparisons that can be made between human CNVs and experimentally induced variants. Here, we used two high-resolution strategies—single nucleotide polymorphism (SNP) arrays and mate-pair sequencing—to compare CNVs that occur constitutionally to those that arise following aphidicolin-induced DNA replication stress in the same human cells. Although the optimized methods provided complementary information, sequencing was more sensitive to small variants and provided superior structural descriptions. The majority of constitutional and all aphidicolin-induced CNVs appear to be formed via homology-independent mechanisms, while aphidicolin-induced CNVs were of a larger median size than constitutional events even when mate-pair data were considered. Aphidicolin thus appears to stimulate formation of CNVs that closely resemble human pathogenic CNVs and the subset of larger nonhomologous constitutional CNVs. PMID:21212237
5′CAG and 5′CTG Repeats Create Differential Impediment to the Progression of a Minimal Reconstituted T4 Replisome Depending on the Concentration of dNTPs

PubMed Central

Delagoutte, Emmanuelle; Baldacci, Giuseppe

2011-01-01

Instability of repetitive sequences originates from strand misalignment during repair or replicative DNA synthesis. To investigate the activity of reconstituted T4 replisomes across trinucleotide repeats (TNRs) during leading strand DNA synthesis, we developed a method to build replication miniforks containing a TNR unit of defined sequence and length. Each minifork consists of three strands, primer, leading strand template, and lagging strand template with a 5′ single-stranded (ss) tail. Each strand is prepared independently, and the minifork is assembled by hybridization of the three strands. Using these miniforks and a minimal reconstituted T4 replisome, we show that during leading strand DNA synthesis, the dNTP concentration dictates which strand of the structure-forming 5′CAG/5′CTG repeat creates the strongest impediment to the minimal replication complex. We discuss this result in the light of the known fluctuation of dNTP concentration during the cell cycle and cell growth and the known concentration balance among individual dNTPs. PMID:22096622
Phylogenetic relationship of Paenibacillus species based on putative replication origin regions and analysis of an yheCD-like sequence found in this region.

PubMed

Iiyama, Kazuhiro; Otao, Masahiro; Mori, Kazuki; Mon, Hiroaki; Lee, Jae Man; Kusakabe, Takahiro; Tashiro, Kousuke; Asano, Shin-Ichiro; Yasunaga-Aoki, Chisa

2014-01-01

To determine the phylogenetic relationship among Paenibacillus species, putative replication origin regions were compared. In the rsmG-gyrA region, gene arrangements in Paenibacillus species were identical to those of Bacillus species, with the exception of an open reading frame (orf14) positioned between gyrB and gyrA, which was observed only in Paenibacillus species. The orf14 product was homologous to the endospore-associated proteins YheC and YheD of Bacillus subtilis. Phylogenetic analysis based on the YheCD proteins suggested that Orf14 could be categorized into the YheC group. In the Paenibacillus genome, DnaA box clusters were found in rpmH-dnaA and dnaA-dnaN intergenic regions, known as box regions C and R, respectively; this localization was similar to that observed in B. halodurans. A phylogenetic tree based on the nucleotide sequences of the whole replication origin regions suggested that P. popilliae, P. thiaminolyticus, and P. dendritiformis are closely related species.

Polymerase ribozyme efficiency increased by G/T-rich DNA oligonucleotides

PubMed Central

Yao, Chengguo; Müller, Ulrich F.

2011-01-01

The RNA world hypothesis states that the early evolution of life went through a stage where RNA served as genome and as catalyst. The replication of RNA world organisms would have been facilitated by ribozymes that catalyze RNA polymerization. To recapitulate an RNA world in the laboratory, a series of RNA polymerase ribozymes was developed previously. However, these ribozymes have a polymerization efficiency that is too low for self-replication, and the most efficient ribozymes prefer one specific template sequence. The limiting factor for polymerization efficiency is the weak sequence-independent binding to its primer/template substrate. Most of the known polymerase ribozymes bind an RNA heptanucleotide to form the P2 duplex on the ribozyme. By modifying this heptanucleotide, we were able to significantly increase polymerization efficiency. Truncations at the 3′-terminus of this heptanucleotide increased full-length primer extension by 10-fold, on a specific template sequence. In contrast, polymerization on several different template sequences was improved dramatically by replacing the RNA heptanucleotide with DNA oligomers containing randomized sequences of 15 nt. The presence of G and T in the random sequences was sufficient for this effect, with an optimal composition of 60% G and 40% T. Our results indicate that these DNA sequences function by establishing many weak and nonspecific base-pairing interactions to the single-stranded portion of the template. Such low-specificity interactions could have had important functions in an RNA world. PMID:21622900
PriC-mediated DNA replication restart requires PriC complex formation with the single-stranded DNA-binding protein.

PubMed

Wessel, Sarah R; Marceau, Aimee H; Massoni, Shawn C; Zhou, Ruobo; Ha, Taekjip; Sandler, Steven J; Keck, James L

2013-06-14

Frequent collisions between cellular DNA replication complexes (replisomes) and obstacles such as damaged DNA or frozen protein complexes make DNA replication fork progression surprisingly sporadic. These collisions can lead to the ejection of replisomes prior to completion of replication, which, if left unrepaired, results in bacterial cell death. As such, bacteria have evolved DNA replication restart mechanisms that function to reload replisomes onto abandoned DNA replication forks. Here, we define a direct interaction between PriC, a key Escherichia coli DNA replication restart protein, and the single-stranded DNA-binding protein (SSB), a protein that is ubiquitously associated with DNA replication forks. PriC/SSB complex formation requires evolutionarily conserved residues from both proteins, including a pair of Arg residues from PriC and the C terminus of SSB. In vitro, disruption of the PriC/SSB interface by sequence changes in either protein blocks the first step of DNA replication restart, reloading of the replicative DnaB helicase onto an abandoned replication fork. Consistent with the critical role of PriC/SSB complex formation in DNA replication restart, PriC variants that cannot bind SSB are non-functional in vivo. Single-molecule experiments demonstrate that PriC binding to SSB alters SSB/DNA complexes, exposing single-stranded DNA and creating a platform for other proteins to bind. These data lead to a model in which PriC interaction with SSB remodels SSB/DNA structures at abandoned DNA replication forks to create a DNA structure that is competent for DnaB loading.
A deep learning method for lincRNA detection using auto-encoder algorithm.

PubMed

Yu, Ning; Yu, Zeng; Pan, Yi

2017-12-06

RNA sequencing technique (RNA-seq) enables scientists to develop novel data-driven methods for discovering more unidentified lincRNAs. Meantime, knowledge-based technologies are experiencing a potential revolution ignited by the new deep learning methods. By scanning the newly found data set from RNA-seq, scientists have found that: (1) the expression of lincRNAs appears to be regulated, that is, the relevance exists along the DNA sequences; (2) lincRNAs contain some conversed patterns/motifs tethered together by non-conserved regions. The two evidences give the reasoning for adopting knowledge-based deep learning methods in lincRNA detection. Similar to coding region transcription, non-coding regions are split at transcriptional sites. However, regulatory RNAs rather than message RNAs are generated. That is, the transcribed RNAs participate the biological process as regulatory units instead of generating proteins. Identifying these transcriptional regions from non-coding regions is the first step towards lincRNA recognition. The auto-encoder method achieves 100% and 92.4% prediction accuracy on transcription sites over the putative data sets. The experimental results also show the excellent performance of predictive deep neural network on the lincRNA data sets compared with support vector machine and traditional neural network. In addition, it is validated through the newly discovered lincRNA data set and one unreported transcription site is found by feeding the whole annotated sequences through the deep learning machine, which indicates that deep learning method has the extensive ability for lincRNA prediction. The transcriptional sequences of lincRNAs are collected from the annotated human DNA genome data. Subsequently, a two-layer deep neural network is developed for the lincRNA detection, which adopts the auto-encoder algorithm and utilizes different encoding schemes to obtain the best performance over intergenic DNA sequence data. Driven by those newly annotated lincRNA data, deep learning methods based on auto-encoder algorithm can exert their capability in knowledge learning in order to capture the useful features and the information correlation along DNA genome sequences for lincRNA detection. As our knowledge, this is the first application to adopt the deep learning techniques for identifying lincRNA transcription sequences.
Regions of conservation and divergence in the 3' untranslated sequences of genomic RNA from Ross River virus isolates.

PubMed

Faragher, S G; Dalgarno, L

1986-07-20

The 3' untranslated (UT) sequences of the genomic RNAs of five geographic variants of the alphavirus Ross River virus (RRV) were determined and compared with the 3' UT sequence of RRV T48, the prototype strain. Part of the 3' UT region of Getah virus, a close serological relative of RRV, was also sequenced. The RRV 3' UT region varies markedly in length between variants. Large deletions or insertions, sequence rearrangements and single nucleotide substitutions are observed. A sequence tract of 49 to 58 nucleotides, which is repeated as four blocks in the RRV T48 3' UT region, occurs only once in the 3' UT region of one RRV strain (NB5092), indicating that the existence of repeat sequence blocks is not essential for RRV replication. However, the precise sequence of the 3' proximal copy of the repeat block and its position relative to the poly(A) tail were identical in all RRV isolates examined, suggesting that it has an important role in RRV replication. Nucleotide substitutions between RRV variants are distributed non-randomly along the length of the 3' UT region. The sequence of 120 to 130 nucleotides adjacent to the poly(A) tail is strongly conserved. Getah virus RNA contains three repeat sequence blocks in the 3' UT region. These are similar in sequence to those in RRV RNA but differ in their arrangement. Homology between the RRV and Getah 3' UT sequences is greatest in the 3' proximal repeat sequence block that shows three differences in 49 nucleotides. The 3' proximal repeat in Getah RNA occurs at the same position, relative to the poly(A) tail, as in all RRV variants. The RRV and Getah virus 3' UT sequences show extensive homology in the region between the 3' proximal repeat and the poly(A) tail but, apart from the repeat blocks themselves, they show no significant homology elsewhere.
Comparison of a newly developed binary typing with ribotyping and multilocus sequence typing methods for Clostridium difficile.

PubMed

Li, Zhirong; Liu, Xiaolei; Zhao, Jianhong; Xu, Kaiyue; Tian, Tiantian; Yang, Jing; Qiang, Cuixin; Shi, Dongyan; Wei, Honglian; Sun, Suju; Cui, Qingqing; Li, Ruxin; Niu, Yanan; Huang, Bixing

2018-04-01

Clostridium difficile is the causative pathogen for antibiotic-related nosocomial diarrhea. For epidemiological study and identification of virulent clones, a new binary typing method was developed for C. difficile in this study. The usefulness of this newly developed optimized 10-loci binary typing method was compared with two widely used methods ribotyping and multilocus sequence typing (MLST) in 189 C. difficile samples. The binary typing, ribotyping and MLST typed the samples into 53 binary types (BTs), 26 ribotypes (RTs), and 33 MLST sequence types (STs), respectively. The typing ability of the binary method was better than that of either ribotyping or MLST expressed in Simpson Index (SI) at 0.937, 0.892 and 0.859, respectively. The ease of testing, portability and cost-effectiveness of the new binary typing would make it a useful typing alternative for outbreak investigations within healthcare facilities and epidemiological research. Copyright © 2018 Elsevier B.V. All rights reserved.
Characterization of HIV Transmission in South-East Austria

PubMed Central

Kessler, Harald H.; Haas, Bernhard; Stelzl, Evelyn; Weninger, Karin; Little, Susan J.; Mehta, Sanjay R.

2016-01-01

To gain deeper insight into the epidemiology of HIV-1 transmission in South-East Austria we performed a retrospective analysis of 259 HIV-1 partial pol sequences obtained from unique individuals newly diagnosed with HIV infection in South-East Austria from 2008 through 2014. After quality filtering, putative transmission linkages were inferred when two sequences were ≤1.5% genetically different. Multiple linkages were resolved into putative transmission clusters. Further phylogenetic analyses were performed using BEAST v1.8.1. Finally, we investigated putative links between the 259 sequences from South-East Austria and all publicly available HIV polymerase sequences in the Los Alamos National Laboratory HIV sequence database. We found that 45.6% (118/259) of the sampled sequences were genetically linked with at least one other sequence from South-East Austria forming putative transmission clusters. Clustering individuals were more likely to be men who have sex with men (MSM; p<0.001), infected with subtype B (p<0.001) or subtype F (p = 0.02). Among clustered males who reported only heterosexual (HSX) sex as an HIV risk, 47% clustered closely with MSM (either as pairs or within larger MSM clusters). One hundred and seven of the 259 sequences (41.3%) from South-East Austria had at least one putative inferred linkage with sequences from a total of 69 other countries. In conclusion, analysis of HIV-1 sequences from newly diagnosed individuals residing in South-East Austria revealed a high degree of national and international clustering mainly within MSM. Interestingly, we found that a high number of heterosexual males clustered within MSM networks, suggesting either linkage between risk groups or misrepresentation of sexual risk behaviors by subjects. PMID:26967154
Characterization of HIV Transmission in South-East Austria.

PubMed

Hoenigl, Martin; Chaillon, Antoine; Kessler, Harald H; Haas, Bernhard; Stelzl, Evelyn; Weninger, Karin; Little, Susan J; Mehta, Sanjay R

2016-01-01

To gain deeper insight into the epidemiology of HIV-1 transmission in South-East Austria we performed a retrospective analysis of 259 HIV-1 partial pol sequences obtained from unique individuals newly diagnosed with HIV infection in South-East Austria from 2008 through 2014. After quality filtering, putative transmission linkages were inferred when two sequences were ≤1.5% genetically different. Multiple linkages were resolved into putative transmission clusters. Further phylogenetic analyses were performed using BEAST v1.8.1. Finally, we investigated putative links between the 259 sequences from South-East Austria and all publicly available HIV polymerase sequences in the Los Alamos National Laboratory HIV sequence database. We found that 45.6% (118/259) of the sampled sequences were genetically linked with at least one other sequence from South-East Austria forming putative transmission clusters. Clustering individuals were more likely to be men who have sex with men (MSM; p<0.001), infected with subtype B (p<0.001) or subtype F (p = 0.02). Among clustered males who reported only heterosexual (HSX) sex as an HIV risk, 47% clustered closely with MSM (either as pairs or within larger MSM clusters). One hundred and seven of the 259 sequences (41.3%) from South-East Austria had at least one putative inferred linkage with sequences from a total of 69 other countries. In conclusion, analysis of HIV-1 sequences from newly diagnosed individuals residing in South-East Austria revealed a high degree of national and international clustering mainly within MSM. Interestingly, we found that a high number of heterosexual males clustered within MSM networks, suggesting either linkage between risk groups or misrepresentation of sexual risk behaviors by subjects.
Dynamic and nucleolin-dependent localization of human cytomegalovirus UL84 to the periphery of viral replication compartments and nucleoli.

PubMed

Bender, Brian J; Coen, Donald M; Strang, Blair L

2014-10-01

Protein-protein and protein-nucleic acid interactions within subcellular compartments are required for viral genome replication. To understand the localization of the human cytomegalovirus viral replication factor UL84 relative to other proteins involved in viral DNA synthesis and to replicating viral DNA in infected cells, we created a recombinant virus expressing a FLAG-tagged version of UL84 (UL84FLAG) and used this virus in immunofluorescence assays. UL84FLAG localization differed at early and late times of infection, transitioning from diffuse distribution throughout the nucleus to exclusion from the interior of replication compartments, with some concentration at the periphery of replication compartments with newly labeled DNA and the viral DNA polymerase subunit UL44. Early in infection, UL84FLAG colocalized with the viral single-stranded DNA binding protein UL57, but colocalization became less prominent as infection progressed. A portion of UL84FLAG also colocalized with the host nucleolar protein nucleolin at the peripheries of both replication compartments and nucleoli. Small interfering RNA (siRNA)-mediated knockdown of nucleolin resulted in a dramatic elimination of UL84FLAG from replication compartments and other parts of the nucleus and its accumulation in the cytoplasm. Reciprocal coimmunoprecipitation of viral proteins from infected cell lysates revealed association of UL84, UL44, and nucleolin. These results indicate that UL84 localization during infection is dynamic, which is likely relevant to its functions, and suggest that its nuclear and subnuclear localization is highly dependent on direct or indirect interactions with nucleolin. Importance: The protein-protein interactions among viral and cellular proteins required for replication of the human cytomegalovirus (HCMV) DNA genome are poorly understood. We sought to understand how an enigmatic HCMV protein critical for virus replication, UL84, localizes relative to other viral and cellular proteins required for HCMV genome replication and replicating viral DNA. We found that UL84 localizes with viral proteins, viral DNA, and the cellular nucleolar protein nucleolin in the subnuclear replication compartments in which viral DNA replication occurs. Unexpectedly, we also found localization of UL84 with nucleolin in nucleoli and showed that the presence of nucleolin is involved in localization of UL84 to the nucleus. These results add to previous work showing the importance of nucleolin in replication compartment architecture and viral DNA synthesis and are relevant to understanding UL84 function. Copyright © 2014, American Society for Microbiology. All Rights Reserved.
Higher order genomic organization and regulatory compartmentalization for cell cycle control at the G1/S-phase transition.

PubMed

Ghule, Prachi N; Seward, David J; Fritz, Andrew J; Boyd, Joseph R; van Wijnen, Andre J; Lian, Jane B; Stein, Janet L; Stein, Gary S

2018-05-10

Fidelity of histone gene regulation, and ultimately of histone protein biosynthesis, is obligatory for packaging of newly replicated DNA into chromatin. Control of histone gene expression within the 3-dimensional context of nuclear organization is reflected by two well documented observations. DNA replication-dependent histone mRNAs are synthesized at specialized subnuclear domains designated histone locus bodies (HLBs), in response to activation of the growth factor dependent Cyclin E/CDK2/HINFP/NPAT pathway at the G1/S transition in mammalian cells. Complete loss of the histone gene regulatory factors HINFP or NPAT disrupts HLB integrity that is necessary for coordinate control of DNA replication and histone gene transcription. Here we review the molecular histone-related requirements for G1/S-phase progression during the cell cycle. Recently developed experimental strategies, now enable us to explore mechanisms involved in dynamic control of histone gene expression in the context of the temporal (cell cycle) and spatial (HLBs) remodeling of the histone gene loci. © 2018 Wiley Periodicals, Inc.
GI-SVM: A sensitive method for predicting genomic islands based on unannotated sequence of a single genome.

PubMed

Lu, Bingxin; Leong, Hon Wai

2016-02-01

Genomic islands (GIs) are clusters of functionally related genes acquired by lateral genetic transfer (LGT), and they are present in many bacterial genomes. GIs are extremely important for bacterial research, because they not only promote genome evolution but also contain genes that enhance adaption and enable antibiotic resistance. Many methods have been proposed to predict GI. But most of them rely on either annotations or comparisons with other closely related genomes. Hence these methods cannot be easily applied to new genomes. As the number of newly sequenced bacterial genomes rapidly increases, there is a need for methods to detect GI based solely on sequences of a single genome. In this paper, we propose a novel method, GI-SVM, to predict GIs given only the unannotated genome sequence. GI-SVM is based on one-class support vector machine (SVM), utilizing composition bias in terms of k-mer content. From our evaluations on three real genomes, GI-SVM can achieve higher recall compared with current methods, without much loss of precision. Besides, GI-SVM allows flexible parameter tuning to get optimal results for each genome. In short, GI-SVM provides a more sensitive method for researchers interested in a first-pass detection of GI in newly sequenced genomes.
Evolution and Diversity in Human Herpes Simplex Virus Genomes

PubMed Central

Gatherer, Derek; Ochoa, Alejandro; Greenbaum, Benjamin; Dolan, Aidan; Bowden, Rory J.; Enquist, Lynn W.; Legendre, Matthieu; Davison, Andrew J.

2014-01-01

Herpes simplex virus 1 (HSV-1) causes a chronic, lifelong infection in >60% of adults. Multiple recent vaccine trials have failed, with viral diversity likely contributing to these failures. To understand HSV-1 diversity better, we comprehensively compared 20 newly sequenced viral genomes from China, Japan, Kenya, and South Korea with six previously sequenced genomes from the United States, Europe, and Japan. In this diverse collection of passaged strains, we found that one-fifth of the newly sequenced members share a gene deletion and one-third exhibit homopolymeric frameshift mutations (HFMs). Individual strains exhibit genotypic and potential phenotypic variation via HFMs, deletions, short sequence repeats, and single-nucleotide polymorphisms, although the protein sequence identity between strains exceeds 90% on average. In the first genome-scale analysis of positive selection in HSV-1, we found signs of selection in specific proteins and residues, including the fusion protein glycoprotein H. We also confirmed previous results suggesting that recombination has occurred with high frequency throughout the HSV-1 genome. Despite this, the HSV-1 strains analyzed clustered by geographic origin during whole-genome distance analysis. These data shed light on likely routes of HSV-1 adaptation to changing environments and will aid in the selection of vaccine antigens that are invariant worldwide. PMID:24227835
T135I substitution in the nonstructural protein 2C enhances foot-and-mouth disease virus replication.

PubMed

Yuan, Tiangang; Wang, Haiwei; Li, Chen; Yang, Decheng; Zhou, Guohui; Yu, Li

2017-12-01

The foot-and-mouth disease virus (FMDV) nonstructural protein 3A plays an important role in viral replication, virulence, and host range. It has been shown that deletions of 10 or 19-20 amino acids in the C-terminal half of 3A attenuate serotype O and C FMDVs, which replicate poorly in bovine cells but normally in porcine-derived cells, and the C-terminal half of 3A is not essential for serotype Asia1 FMDV replication in BHK-21 cells. In this study, we constructed a 3A deletion FMDV mutant based on a serotype O FMDV, the wild-type virus O/YS/CHA/05, with a 60-amino acid deletion in the 3A protein sequence, between residues 84 and 143. The rescued virus O/YS/CHA/05-Δ3A exhibited slower growth kinetics and formed smaller plaques compared to O/YS/CHA/05 in both BHK-21 and IBRS-2 cells, indicating that the 60-amino acid deletion in the 3A protein impaired FMDV replication. After 14 passages in BHK-21 cells, the replication capacity of the passaged virus O/YS/CHA/05-Δ3A-P14 returned to a level similar to the wild-type virus, suggesting that amino acid substitutions responsible for the enhanced replication capacity occurred in the genome of O/YS/CHA/05-Δ3A-P14. By sequence analysis, two amino acid substitutions, P153L in VP1 and T135I in 2C, were found in the O/YS/CHA/05-Δ3A-P14 genome compared to the O/YS/CHA/05-Δ3A genome. Subsequently, the amino acid substitutions VP1 P153L and 2C T135I were separately introduced into O/YS/CHA/05-Δ3A to rescue mutant viruses for examining their growth kinetics. Results showed that the 2C T135I instead of the VP1 P153L enhanced the virus replication capacity. The 2C T135I substitution also improved the replication of the wild-type virus, indicating that the effect of 2C T135I substitution on FMDV replication is not associated with the 3A deletion. Furthermore, our results showed that the T135I substitution in the nonstructural protein 2C enhanced O/YS/CHA/05 replication through promoting viral RNA synthesis.
Acousto-optic replication of ultrashort laser pulses

NASA Astrophysics Data System (ADS)

Yushkov, Konstantin B.; Molchanov, Vladimir Ya.; Ovchinnikov, Andrey V.; Chefonov, Oleg V.

2017-10-01

Precisely controlled sequences of ultrashort laser pulses are required in various scientific and engineering applications. We developed a phase-only acousto-optic pulse shaping method for replication of ultrashort laser pulses in a TW laser system. A sequence of several Fourier-transform-limited pulses is generated from a single femtosecond laser pulse by means of applying a piecewise linear phase modulation over the whole emission spectrum. Analysis demonstrates that the main factor which limits maximum delay between the pulse replicas is spectral resolution of the acousto-optic dispersive delay line used for pulse shaping. In experiments with a Cr:forsterite laser system, we obtained delays from 0.3 to 3.5 ps between two replicas of 190 fs transform-limited pulses at the central wavelength of laser emission, 1230 nm.
MicroRNA reduction of neuronal West Nile virus replication attenuates and affords a protective immune response in mice

PubMed Central

Brostoff, Terza; Pesavento, Patricia A.; Barker, Christopher M.; Kenney, Joan L.; Dietrich, Elizabeth A.; Duggal, Nisha K.; Bosco-Lauth, Angela M.; Brault, Aaron C.

2017-01-01

West Nile virus (WNV) is an important agent of human encephalitis that has quickly become endemic across much of the United States since its identification in North America in 1999. While the majority (~75%) of infections are subclinical, neurologic disease can occur in a subset of cases, with outcomes including permanent neurologic damage and death. Currently, there are no WNV vaccines approved for use in humans. This study introduces a novel vaccine platform for WNV to reduce viral replication in the central nervous system while maintaining peripheral replication to elicit strong neutralizing antibody titers. Vaccine candidates were engineered to incorporate microRNA (miRNA) target sequences for a cognate miRNA expressed only in neurons, allowing the host miRNAs to target viral transcription through endogenous RNA silencing. To maintain stability, these targets were incorporated in multiple locations within the 3′-untranslated region, flanking sequences essential for viral replication without affecting the viral open reading frame. All candidates replicated comparably to wild type WNV in vitro within cells that did not express the cognate miRNA. Insertional control viruses were also capable of neuroinvasion and neurovirulence in vivo in CD-1 mice. Vaccine viruses were safe at all doses tested and did not demonstrate mutations associated with a reversion to virulence when serially passaged in mice. All vaccine constructs were protective from lethal challenge in mice, producing 93–100% protection at the highest dose tested. Overall, this is a safe and effective attenuation strategy with broad potential application for vaccine development. PMID:27637937
MicroRNA reduction of neuronal West Nile virus replication attenuates and affords a protective immune response in mice.

PubMed

Brostoff, Terza; Pesavento, Patricia A; Barker, Christopher M; Kenney, Joan L; Dietrich, Elizabeth A; Duggal, Nisha K; Bosco-Lauth, Angela M; Brault, Aaron C

2016-10-17

West Nile virus (WNV) is an important agent of human encephalitis that has quickly become endemic across much of the United States since its identification in North America in 1999. While the majority (∼75%) of infections are subclinical, neurologic disease can occur in a subset of cases, with outcomes including permanent neurologic damage and death. Currently, there are no WNV vaccines approved for use in humans. This study introduces a novel vaccine platform for WNV to reduce viral replication in the central nervous system while maintaining peripheral replication to elicit strong neutralizing antibody titers. Vaccine candidates were engineered to incorporate microRNA (miRNA) target sequences for a cognate miRNA expressed only in neurons, allowing the host miRNAs to target viral transcription through endogenous RNA silencing. To maintain stability, these targets were incorporated in multiple locations within the 3'-untranslated region, flanking sequences essential for viral replication without affecting the viral open reading frame. All candidates replicated comparably to wild type WNV in vitro within cells that did not express the cognate miRNA. Insertional control viruses were also capable of neuroinvasion and neurovirulence in vivo in CD-1 mice. Vaccine viruses were safe at all doses tested and did not demonstrate mutations associated with a reversion to virulence when serially passaged in mice. All vaccine constructs were protective from lethal challenge in mice, producing 93-100% protection at the highest dose tested. Overall, this is a safe and effective attenuation strategy with broad potential application for vaccine development. Published by Elsevier Ltd.
A Bromodomain-Containing Protein from Tomato Specifically Binds Potato Spindle Tuber Viroid RNA In Vitro and In Vivo

PubMed Central

Martínez de Alba, Angel Emilio; Sägesser, Rudolf; Tabler, Martin; Tsagris, Mina

2003-01-01

For the identification of RNA-binding proteins that specifically interact with potato spindle tuber viroid (PSTVd), we subjected a tomato cDNA expression library prepared from viroid-infected leaves to an RNA ligand screening procedure. We repeatedly identified cDNA clones that expressed a protein of 602 amino acids. The protein contains a bromodomain and was termed viroid RNA-binding protein 1 (VIRP1). The specificity of interaction of VIRP1 with viroid RNA was studied by different methodologies, which included Northwestern blotting, plaque lift, and electrophoretic mobility shift assays. VIRP1 interacted strongly and specifically with monomeric and oligomeric PSTVd positive-strand RNA transcripts. Other RNAs, for example, U1 RNA, did not bind to VIRP1. Further, we could immunoprecipitate complexes from infected tomato leaves that contained VIRP1 and viroid RNA in vivo. Analysis of the protein sequence revealed that VIRP1 is a member of a newly identified family of transcriptional regulators associated with chromatin remodeling. VIRP1 is the first member of this family of proteins, for which a specific RNA-binding activity is shown. A possible role of VIRP1 in viroid replication and in RNA mediated chromatin remodeling is discussed. PMID:12915580
A computational model for predicting integrase catalytic domain of retrovirus.

PubMed

Wu, Sijia; Han, Jiuqiang; Zhang, Xinman; Zhong, Dexing; Liu, Ruiling

2017-06-21

Integrase catalytic domain (ICD) is an essential part in the retrovirus for integration reaction, which enables its newly synthesized DNA to be incorporated into the DNA of infected cells. Owing to the crucial role of ICD for the retroviral replication and the absence of an equivalent of integrase in host cells, it is comprehensible that ICD is a promising drug target for therapeutic intervention. However, annotated ICDs in UniProtKB database have still been insufficient for a good understanding of their statistical characteristics so far. Accordingly, it is of great importance to put forward a computational ICD model in this work to annotate these domains in the retroviruses. The proposed model then discovered 11,660 new putative ICDs after scanning sequences without ICD annotations. Subsequently in order to provide much confidence in ICD prediction, it was tested under different cross-validation methods, compared with other database search tools, and verified on independent datasets. Furthermore, an evolutionary analysis performed on the annotated ICDs of retroviruses revealed a tight connection between ICD and retroviral classification. All the datasets involved in this paper and the application software tool of this model can be available for free download at https://sourceforge.net/projects/icdtool/files/?source=navbar. Copyright © 2017 Elsevier Ltd. All rights reserved.
Broad Spectrum of Mimiviridae Virophage Allows Its Isolation Using a Mimivirus Reporter

PubMed Central

Gaia, Morgan; Pagnier, Isabelle; Campocasso, Angélique; Fournous, Ghislain; Raoult, Didier; La Scola, Bernard

2013-01-01

The giant virus Mimiviridae family includes 3 groups of viruses: group A (includes Acanthamoeba polyphaga Mimivirus), group B (includes Moumouvirus) and group C (includes Megavirus chilensis). Virophages have been isolated with both group A Mimiviridae (the Mamavirus strain) and the related Cafeteria roenbergensis virus, and they have also been described by bioinformatic analysis of the Phycodnavirus. Here, we found that the first two strains of virophages isolated with group A Mimiviridae can multiply easily in groups B and C and play a role in gene transfer among these virus subgroups. To isolate new virophages and their Mimiviridae host in the environment, we used PCR to identify a sample with a virophage and a group C Mimiviridae that failed to grow on amoeba. Moreover, we showed that virophages reduce the pathogenic effect of Mimivirus (plaque formation), establishing its parasitic role on Mimivirus. We therefore developed a co-culture procedure using Acanthamoeba polyphaga and Mimivirus to recover the detected virophage and then sequenced the virophage's genome. We present this technique as a novel approach to isolating virophages. We demonstrated that the newly identified virophages replicate in the viral factories of all three groups of Mimiviridae, suggesting that the spectrum of virophages is not limited to their initial host. PMID:23596530
Molecular Basis of the Binding of YAP Transcriptional Regulator to the ErbB4 Receptor Tyrosine Kinase

PubMed Central

Schuchardt, Brett J.; Bhat, Vikas; Mikles, David C.; McDonald, Caleb B.; Sudol, Marius; Farooq, Amjad

2014-01-01

The newly discovered transactivation function of ErbB4 receptor tyrosine kinase is believed to be mediated by virtue of the ability of its proteolytically-cleaved intracellular domain (ICD) to physically associate with YAP2 transcriptional regulator. In an effort to unearth the molecular basis of YAP2-ErbB4 interaction, we have conducted a detailed biophysical analysis of the binding of WW domains of YAP2 to PPXY motifs located within the ICD of ErbB4. Our data show that the WW1 domain of YAP2 binds to PPXY motifs within the ICD in a differential manner and that this behavior is by and large replicated by the WW2 domain. Remarkably, while both WW domains absolutely require the integrity of the PPXY consensus sequence, non-consensus residues within and flanking this motif do not appear to be critical for binding. In spite of this shared mode of binding, the WW domains of YAP2 display distinct conformational dynamics in complex with PPXY motifs derived from ErbB4. Collectively, our study lends new insights into the molecular basis of a key protein-protein interaction involved in a diverse array of cellular processes. PMID:24472438
Molecular basis of the binding of YAP transcriptional regulator to the ErbB4 receptor tyrosine kinase.

PubMed

Schuchardt, Brett J; Bhat, Vikas; Mikles, David C; McDonald, Caleb B; Sudol, Marius; Farooq, Amjad

2014-06-01

The newly discovered transactivation function of ErbB4 receptor tyrosine kinase is believed to be mediated by virtue of the ability of its proteolytically-cleaved intracellular domain (ICD) to physically associate with YAP2 transcriptional regulator. In an effort to unearth the molecular basis of YAP2-ErbB4 interaction, we have conducted a detailed biophysical analysis of the binding of WW domains of YAP2 to PPXY motifs located within the ICD of ErbB4. Our data show that the WW1 domain of YAP2 binds to PPXY motifs within the ICD in a differential manner and that this behavior is by and large replicated by the WW2 domain. Remarkably, while both WW domains absolutely require the integrity of the PPXY consensus sequence, non-consensus residues within and flanking this motif do not appear to be critical for binding. In spite of this shared mode of binding, the WW domains of YAP2 display distinct conformational dynamics in complex with PPXY motifs derived from ErbB4. Collectively, our study lends new insights into the molecular basis of a key protein-protein interaction involved in a diverse array of cellular processes. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Changes of motor-cortical oscillations associated with motor learning.

PubMed

Pollok, B; Latz, D; Krause, V; Butz, M; Schnitzler, A

2014-09-05

Motor learning results from practice but also between practice sessions. After skill acquisition early consolidation results in less interference with other motor tasks and even improved performance of the newly learned skill. A specific significance of the primary motor cortex (M1) for early consolidation has been suggested. Since synchronized oscillatory activity is assumed to facilitate neuronal plasticity, we here investigate alterations of motor-cortical oscillations by means of event-related desynchronization (ERD) at alpha (8-12 Hz) and beta (13-30 Hz) frequencies in healthy humans. Neuromagnetic activity was recorded using a 306-channel whole-head magnetoencephalography (MEG) system. ERD was investigated in 15 subjects during training on a serial reaction time task and 10 min after initial training. The data were compared with performance during a randomly varying sequence serving as control condition. The data reveal a stepwise decline of alpha-band ERD associated with faster reaction times replicating previous findings. The amount of beta-band suppression was significantly correlated with reduction of reaction times. While changes of alpha power have been related to lower cognitive control after initial skill acquisition, the present data suggest that the amount of beta suppression represents a neurophysiological marker of early cortical reorganization associated with motor learning. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.
Interaction of the host protein NbDnaJ with Potato virus X minus-strand stem-loop 1 RNA and capsid protein affects viral replication and movement.

PubMed

Cho, Sang-Yun; Cho, Won Kyong; Sohn, Seong-Han; Kim, Kook-Hyung

2012-01-06

Plant viruses must interact with host cellular components to replicate and move from cell to cell. In the case of Potato virus X (PVX), it carries stem-loop 1 (SL1) RNA essential for viral replication and movement. Using two-dimensional electrophoresis northwestern blot analysis, we previously identified several host proteins that bind to SL1 RNA. Of those, we further characterized a DnaJ-like protein from Nicotiana benthamiana named NbDnaJ. An electrophoretic mobility shift assay confirmed that NbDnaJ binds only to SL1 minus-strand RNA, and bimolecular fluorescence complementation (BiFC) indicated that NbDnaJ interacts with PVX capsid protein (CP). Using a series of deletion mutants, the C-terminal region of NbDnaJ was found to be essential for the interaction with PVX CP. The expression of NbDnaJ significantly changed upon infection with different plant viruses such as PVX, Tobacco mosaic virus, and Cucumber mosaic virus, but varied depending on the viral species. In transient experiments, both PVX replication and movement were inhibited in plants that over-expressed NbDnaJ but accelerated in plants in which NbDnaJ was silenced. In summary, we suggest that the newly identified NbDnaJ plays a role in PVX replication and movement by interacting with SL1(-) RNA and PVX CP. Copyright © 2011 Elsevier Inc. All rights reserved.
Dependence of erythroid differentiation on cell replication in dimethyl sulfoxide-treated friend leukemia-virus-infected cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiens, A.W.; McClintock, P.R.; Papaconstantinou, J.

1976-01-01

The dimethyl sulfoxide (Me/sub 2/SO)-mediated induction of hemoglobin synthesis in Friend leukemia cells (a murine erythroblastoid cell line) is coupled with the number of cell replications occurring in the presence of inducer. Varying concentrations of proflavine increase the generation time of these cells from 24 hours to over 50 hours, and in each case the induction of hemoglobin synthesis follows the completion of two cell doublings. Once the induction is initiated, the rate of hemoglobin accumulation is not affected by proflavine. These data indicate that proflavine does not affect the transcription or translation of globin mRNA and that the delaymore » in induction of hemoglobin synthesis is due to its effect on the rate of cellular replication. In experiments using high concentrations of thymidine to block replication, hemoglobin accumulation is prevented only if the cells are blocked prior to 36 hours after Me/sub 2/SO addition. If the cells have completed two generations in the presence of Me/sub 2/SO, there is no effect upon their ability to synthesize hemoglobin even though their growth is arrested. Thus, the inhibition of hemoglobin synthesis by proflavine is not merely the result of a toxic effect on newly subcultured cells but is due to its effect on cellular replication. These experiments confirm that, after addition of Me/sub 2/SO, Friend leukemia cells require more than one complete cell cycle in order to synthesize hemoglobin.« less
Association of rs1344706 in the ZNF804A gene with schizophrenia in a case/control sample from Indonesia.

PubMed

Schwab, Sibylle G; Kusumawardhani, Agung A A A; Dai, Nan; Qin, WenWen; Wildenauer, Mutiara D B; Agiananda, Feranindhya; Amir, Nurmiati; Antoni, Ronald; Arsianti, Tiana; Asmarahadi, Asmarahadi; Diatri, Hervita; Djatmiko, Prianto; Irmansyah, Irmansyah; Khalimah, Siti; Kusumadewi, Irmia; Kusumaningrum, Profitasari; Lukman, Petrin R; Mustar, Lukman; Nasrun, Martina W; Naswati, Safyuni; Prasetiyawan, Prasetiyawan; Semen, Gerald M; Siste, Kristiana; Tobing, Heriani; Widiasih, Natalia; Wiguna, Tjhin; Wulandari, Widayanti Dewi; Benyamin, Beben; Wildenauer, Dieter B

2013-06-01

Association of rs1344706 in the ZNF804A gene (2q32.1) with schizophrenia was first reported in a genome wide scan conducted in a sample of 479 cases and replicated in 6666 cases. Subsequently, evidence by replication was obtained in several samples with European- and Asian ancestral background. We report ascertainment, clinical characterization, quality control, and determination of ancestral background of a case control sample from Indonesia, comprising 1067 cases and 1111 ancestry matched controls. Genotyping was performed using a fluorescence-based allelic discrimination assay (TaqMan SNP genotyping assay) and a newly designed PCR-RFLP assay for confirmation of rs1344706 genotypes. We confirmed association of the T-allele of rs1344706 with schizophrenia in a newly ascertained sample from Indonesia with Southeast Asian ancestral background (P=0.019, OR=1.155, 95%, CI 1.025-1.301). In addition, we studied several SNPs in the vicinity of rs1344706, for which nominally significant results had been reported. None of the association P values of the additional SNPs exceeded that of rs1344706. We provide additional evidence for association of the ZNF804A gene with schizophrenia. We conclude that rs1344706 or a yet unknown polymorphism in linkage disequilibrium is also involved in conferring susceptibility to schizophrenia in samples with different (Asian) ancestral backgrounds. Copyright © 2013 Elsevier B.V. All rights reserved.
Replication Research in Pedagogical Approaches to Formulaic Sequences: Jones & Haywood (2004) and Alali & Schmitt (2012)

ERIC Educational Resources Information Center

Coxhead, Averil

2018-01-01

Research into the formulaic nature of language has grown in size and scale in the last 20 years or more, much of it based in corpus studies and involving the identification and categorisation of formulas. Research suggests that there are benefits for second and foreign language learners recognising formulaic sequences when listening and reading,…
Meta-analysis of RNA-Seq data across cohorts in a multi-season feed efficiency study of crossbred beef steers accounts for biological and technical variability within season

USDA-ARS?s Scientific Manuscript database

High-throughput sequencing is often used for studies of the transcriptome, particularly for comparisons between experimental conditions. Due to sequencing costs, a limited number of biological replicates are typically considered in such experiments, leading to low detection power for differential ex...
Activation of a yeast replication origin near a double-stranded DNA break.

PubMed

Raghuraman, M K; Brewer, B J; Fangman, W L

1994-03-01

Irradiation in the G1 phase of the cell cycle delays the onset of DNA synthesis and transiently inhibits the activation of replication origins in mammalian cells. It has been suggested that this inhibition is the result of the loss of torsional tension in the DNA after it has been damaged. Because irradiation causes DNA damage at an undefined number of nonspecific sites in the genome, it is not known how cells respond to limited DNA damage, and how replication origins in the immediate vicinity of a damage site would behave. Using the sequence-specific HO endonuclease, we have created a defined double-stranded DNA break in a centromeric plasmid in G1-arrested cells of the yeast Saccharomyces cerevisiae. We show that replication does initiate at the origin on the cut plasmid, and that the plasmid replicates early in the S phase after linearization in vivo. These observations suggest that relaxation of a supercoiled DNA domain in yeast need not inactivate replication origins within that domain. Furthermore, these observations rule out the possibility that the late replication context associated with chromosomal termini is a consequence of DNA ends.
Suppressors of dGTP Starvation in Escherichia coli

PubMed Central

Itsko, Mark

2017-01-01

ABSTRACT dGTP starvation, a newly discovered phenomenon in which Escherichia coli cells are starved specifically for the DNA precursor dGTP, leads to impaired growth and, ultimately, cell death. Phenomenologically, it represents an example of nutritionally induced unbalanced growth: cell mass amplifies normally as dictated by the nutritional status of the medium, but DNA content growth is specifically impaired. The other known example of such a condition, thymineless death (TLD), involves starvation for the DNA precursor dTTP, which has been found to have important chemotherapeutic applications. Experimentally, dGTP starvation is induced by depriving an E. coli gpt optA1 strain of its required purine source, hypoxanthine. In our studies of this phenomenon, we noted the emergence of a relatively high frequency of suppressor mutants that proved resistant to the treatment. To study such suppressors, we used next-generation sequencing on a collection of independently obtained mutants. A significant fraction was found to carry a defect in the PurR transcriptional repressor, controlling de novo purine biosynthesis, or in its downstream purEK operon. Thus, upregulation of de novo purine biosynthesis appears to be a major mode of overcoming the lethal effects of dGTP starvation. In addition, another large fraction of the suppressors contained a large tandem duplication of a 250- to 300-kb genomic region that included the purEK operon as well as the acrAB-encoded multidrug efflux system. Thus, the suppressive effects of the duplications could potentially involve beneficial effects of a number of genes/operons within the amplified regions. IMPORTANCE Concentrations of the four precursors for DNA synthesis (2′-deoxynucleoside-5′-triphosphates [dNTPs]) are critical for both the speed of DNA replication and its accuracy. Previously, we investigated consequences of dGTP starvation, where the DNA precursor dGTP was specifically reduced to a low level. Under this condition, E. coli cells continued cell growth but eventually developed a DNA replication defect, leading to cell death due to formation of unresolvable DNA structures. Nevertheless, dGTP-starved cultures eventually resumed growth due to the appearance of resistant mutants. Here, we used whole-genome DNA sequencing to identify the responsible suppressor mutations. We show that the majority of suppressors can circumvent death by upregulating purine de novo biosynthesis, leading to restoration of dGTP to acceptable levels. PMID:28373271
Role for a region of helically unstable DNA within the Epstein-Barr virus latent cycle origin of DNA replication oriP in origin function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polonskaya, Zhanna; Benham, Craig J.; Hearing, Janet

The minimal replicator of the Epstein-Barr virus (EBV) latent cycle origin of DNA replication oriP is composed of two binding sites for the Epstein-Barr virus nuclear antigen-1 (EBNA-1) and flanking inverted repeats that bind the telomere repeat binding factor TRF2. Although not required for minimal replicator activity, additional binding sites for EBNA-1 and TRF2 and one or more auxiliary elements located to the right of the EBNA-1/TRF2 sites are required for the efficient replication of oriP plasmids. Another region of oriP that is predicted to be destabilized by DNA supercoiling is shown here to be an important functional component ofmore » oriP. The ability of DNA fragments of unrelated sequence and possessing supercoiled-induced DNA duplex destabilized (SIDD) structures, but not fragments characterized by helically stable DNA, to substitute for this component of oriP demonstrates a role for the SIDD region in the initiation of oriP-plasmid DNA replication.« less
Short communication: Nitazoxanide inhibits HIV viral replication in monocyte-derived macrophages.

PubMed

Gekonge, Bethsebah; Bardin, Matthew C; Montaner, Luis J

2015-02-01

We document the anti-HIV activity of nitazoxanide (NTZ), the first member of the thiazolide class of antiinfective drugs, originally effective against enteritis caused by Cryptosporidium parvum and Giardia lamblia. NTZ has been administered extensively worldwide, with no severe toxicities associated with its use. Here, we show for the first time that NTZ decreases HIV-1 replication in monocyte-derived macrophages (MDM) if present before or during HIV-1 infection. This NTZ effect is associated with downregulation of HIV-1 receptors CD4 and CCR5, and increasing gene expression of host cell anti-HIV resistance factors APOBEC3A/3G and tetherin. As NTZ is already in clinical use for other conditions, this newly described anti-HIV activity in MDM may facilitate innovative intensification strategies against HIV-1 when combined with current antiretroviral drug regimens.
Cells of pea (Pisum sativum) that differentiate from G2 phase have extrachromosomal DNA.

PubMed Central

Van't Hof, J; Bjerknes, C A

1982-01-01

Velocity sedimentation in an alkaline sucrose gradient of newly replicated chromosomal DNA revealed the presence of extrachromosomal DNA that was not replicated by differentiating cells in the elongation zone. The extrachromosomal DNA had a number average molecular weight of 12 X 10(6) to 15 X 10(6) and a weight average molecular weight of 25 X 10(6), corresponding to about 26 X 10(6) and 50 X 10(6) daltons, respectively, of double-stranded DNA. The molecules were stable, lasting at least 72 h after being formed. Concurrent measurements by velocity sedimentation, autoradiography, and cytophotometry of isolated nuclei indicated that the extrachromosomal molecules were associated with root-tip cells that stopped dividing and differentiated from G2 phase but not with those that stopped dividing and differentiated from G1 phase. PMID:7110135
Functional centromeres determine the activation time of pericentric origins of DNA replication in Saccharomyces cerevisiae.

PubMed

Pohl, Thomas J; Brewer, Bonita J; Raghuraman, M K

2012-01-01

The centromeric regions of all Saccharomyces cerevisiae chromosomes are found in early replicating domains, a property conserved among centromeres in fungi and some higher eukaryotes. Surprisingly, little is known about the biological significance or the mechanism of early centromere replication; however, the extensive conservation suggests that it is important for chromosome maintenance. Do centromeres ensure their early replication by promoting early activation of nearby origins, or have they migrated over evolutionary time to reside in early replicating regions? In Candida albicans, a neocentromere contains an early firing origin, supporting the first hypothesis but not addressing whether the new origin is intrinsically early firing or whether the centromere influences replication time. Because the activation time of individual origins is not an intrinsic property of S. cerevisiae origins, but is influenced by surrounding sequences, we sought to test the hypothesis that centromeres influence replication time by moving a centromere to a late replication domain. We used a modified Meselson-Stahl density transfer assay to measure the kinetics of replication for regions of chromosome XIV in which either the functional centromere or a point-mutated version had been moved near origins that reside in a late replication region. We show that a functional centromere acts in cis over a distance as great as 19 kb to advance the initiation time of origins. Our results constitute a direct link between establishment of the kinetochore and the replication initiation machinery, and suggest that the proposed higher-order structure of the pericentric chromatin influences replication initiation.
Functional Centromeres Determine the Activation Time of Pericentric Origins of DNA Replication in Saccharomyces cerevisiae

PubMed Central

Pohl, Thomas J.; Brewer, Bonita J.; Raghuraman, M. K.

2012-01-01

The centromeric regions of all Saccharomyces cerevisiae chromosomes are found in early replicating domains, a property conserved among centromeres in fungi and some higher eukaryotes. Surprisingly, little is known about the biological significance or the mechanism of early centromere replication; however, the extensive conservation suggests that it is important for chromosome maintenance. Do centromeres ensure their early replication by promoting early activation of nearby origins, or have they migrated over evolutionary time to reside in early replicating regions? In Candida albicans, a neocentromere contains an early firing origin, supporting the first hypothesis but not addressing whether the new origin is intrinsically early firing or whether the centromere influences replication time. Because the activation time of individual origins is not an intrinsic property of S. cerevisiae origins, but is influenced by surrounding sequences, we sought to test the hypothesis that centromeres influence replication time by moving a centromere to a late replication domain. We used a modified Meselson-Stahl density transfer assay to measure the kinetics of replication for regions of chromosome XIV in which either the functional centromere or a point-mutated version had been moved near origins that reside in a late replication region. We show that a functional centromere acts in cis over a distance as great as 19 kb to advance the initiation time of origins. Our results constitute a direct link between establishment of the kinetochore and the replication initiation machinery, and suggest that the proposed higher-order structure of the pericentric chromatin influences replication initiation. PMID:22589733
Replication and meiotic transmission of yeast ribosomal RNA genes.

PubMed

Brewer, B J; Zakian, V A; Fangman, W L

1980-11-01

The yeast Saccharomyces cerevisiae has approximately 120 genes for the ribosomal RNAs (rDNA) which are organized in tandem within chromosomal DNA. These multiple-copy genes are homogeneous in sequence but can undergo changes in copy number and topology. To determine if these changes reflect unusual features of rDNA metabolism, we have examined both the replication of rDNA in the mitotic cell cycle and the inheritance of rDNA during meiosis. The results indicate that rDNA behaves identically to chromosomal DNA: each rDNA unit is replicated once during the S phase of each cell cycle and each unit is conserved through meiosis. Therefore, the flexibility in copy number and topology of rDNA does not arise from the selective replication of units in each S phase nor by the selective inheritance of units in meiosis.
The magic shrinking machine revisited: The presence of props at recall facilitates memory in 3-year-olds.

PubMed

Dahl, Jonna J; Kingo, Osman S; Krøjgaard, Peter

2015-12-01

In a seminal study Simcock and Hayne (2002) showed that 3-year-olds were unable to use newly acquired words to describe a "magic" event experienced 6 or 12 months earlier. In the reference study the children's verbal recall was tested without props being present. Inspired by recent evidence, the original design was replicated, testing 33-and 39-month-olds (n = 180), but with props present at recall while controlling for potential online reasoning. The results revealed that the children did use newly acquired words to describe their preverbal memory. Thus, the present study shows that nonverbal memories can be verbalized if the recall setting provides a high level of contextual support, a finding relevant to researchers investigating the offset of childhood amnesia. (c) 2015 APA, all rights reserved).
Novel cis-acting element within the capsid-coding region enhances flavivirus viral-RNA replication by regulating genome cyclization.

PubMed

Liu, Zhong-Yu; Li, Xiao-Feng; Jiang, Tao; Deng, Yong-Qiang; Zhao, Hui; Wang, Hong-Jiang; Ye, Qing; Zhu, Shun-Ya; Qiu, Yang; Zhou, Xi; Qin, E-De; Qin, Cheng-Feng

2013-06-01

cis-Acting elements in the viral genome RNA (vRNA) are essential for the translation, replication, and/or encapsidation of RNA viruses. In this study, a novel conserved cis-acting element was identified in the capsid-coding region of mosquito-borne flavivirus. The downstream of 5' cyclization sequence (5'CS) pseudoknot (DCS-PK) element has a three-stem pseudoknot structure, as demonstrated by structure prediction and biochemical analysis. Using dengue virus as a model, we show that DCS-PK enhances vRNA replication and that its function depends on its secondary structure and specific primary sequence. Mutagenesis revealed that the highly conserved stem 1 and loop 2, which are involved in potential loop-helix interactions, are crucial for DCS-PK function. A predicted loop 1-stem 3 base triple interaction is important for the structural stability and function of DCS-PK. Moreover, the function of DCS-PK depends on its position relative to the 5'CS, and the presence of DCS-PK facilitates the formation of 5'-3' RNA complexes. Taken together, our results reveal that the cis-acting element DCS-PK enhances vRNA replication by regulating genome cyclization, and DCS-PK might interplay with other cis-acting elements to form a functional vRNA cyclization domain, thus playing critical roles during the flavivirus life cycle and evolution.
Novel cis-Acting Element within the Capsid-Coding Region Enhances Flavivirus Viral-RNA Replication by Regulating Genome Cyclization

PubMed Central

Liu, Zhong-Yu; Li, Xiao-Feng; Jiang, Tao; Deng, Yong-Qiang; Zhao, Hui; Wang, Hong-Jiang; Ye, Qing; Zhu, Shun-Ya; Qiu, Yang; Zhou, Xi; Qin, E-De

2013-01-01

cis-Acting elements in the viral genome RNA (vRNA) are essential for the translation, replication, and/or encapsidation of RNA viruses. In this study, a novel conserved cis-acting element was identified in the capsid-coding region of mosquito-borne flavivirus. The downstream of 5′ cyclization sequence (5′CS) pseudoknot (DCS-PK) element has a three-stem pseudoknot structure, as demonstrated by structure prediction and biochemical analysis. Using dengue virus as a model, we show that DCS-PK enhances vRNA replication and that its function depends on its secondary structure and specific primary sequence. Mutagenesis revealed that the highly conserved stem 1 and loop 2, which are involved in potential loop-helix interactions, are crucial for DCS-PK function. A predicted loop 1-stem 3 base triple interaction is important for the structural stability and function of DCS-PK. Moreover, the function of DCS-PK depends on its position relative to the 5′CS, and the presence of DCS-PK facilitates the formation of 5′-3′ RNA complexes. Taken together, our results reveal that the cis-acting element DCS-PK enhances vRNA replication by regulating genome cyclization, and DCS-PK might interplay with other cis-acting elements to form a functional vRNA cyclization domain, thus playing critical roles during the flavivirus life cycle and evolution. PMID:23576500
Spontaneous Chloroplast Mutants Mostly Occur by Replication Slippage and Show a Biased Pattern in the Plastome of Oenothera.

PubMed

Massouh, Amid; Schubert, Julia; Yaneva-Roder, Liliya; Ulbricht-Jones, Elena S; Zupok, Arkadiusz; Johnson, Marc T J; Wright, Stephen I; Pellizzer, Tommaso; Sobanski, Johanna; Bock, Ralph; Greiner, Stephan

2016-04-01

Spontaneous plastome mutants have been used as a research tool since the beginning of genetics. However, technical restrictions have severely limited their contributions to research in physiology and molecular biology. Here, we used full plastome sequencing to systematically characterize a collection of 51 spontaneous chloroplast mutants in Oenothera (evening primrose). Most mutants carry only a single mutation. Unexpectedly, the vast majority of mutations do not represent single nucleotide polymorphisms but are insertions/deletions originating from DNA replication slippage events. Only very few mutations appear to be caused by imprecise double-strand break repair, nucleotide misincorporation during replication, or incorrect nucleotide excision repair following oxidative damage. U-turn inversions were not detected. Replication slippage is induced at repetitive sequences that can be very small and tend to have high A/T content. Interestingly, the mutations are not distributed randomly in the genome. The underrepresentation of mutations caused by faulty double-strand break repair might explain the high structural conservation of seed plant plastomes throughout evolution. In addition to providing a fully characterized mutant collection for future research on plastid genetics, gene expression, and photosynthesis, our work identified the spectrum of spontaneous mutations in plastids and reveals that this spectrum is very different from that in the nucleus. © 2016 American Society of Plant Biologists. All rights reserved.
Two DNA-binding factors recognize specific sequences at silencers, upstream activating sequences, autonomously replicating sequences, and telomeres in Saccharomyces cerevisiae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buchman, A.R.; Kimmerly, W.J.; Rine, J.

1988-01-01

Two DNA-binding factors from Saccharomyces cerevisiae have been characterized, GRFI (general regulatory factor I) and ABFI (ARS-binding factor I), that recognize specific sequences within diverse genetic elements. GRFI bound to sequences at the negative regulatory elements (silencers) of the silent mating type loci HML E and HMR E and to the upstream activating sequence (UAS) required for transcription of the MAT ..cap alpha.. genes. A putative conserved UAS located at genes involved in translation (RPG box) was also recognized by GRFI. In addition, GRFI bound with high affinity to sequences within the (C/sub 1-3/A)-repeat region at yeast telomeres. Binding sitesmore » for GRFI with the highest affinity appeared to be of the form 5'-(A/G)(A/C)ACCCAN NCA(T/C)(T/C)-3', where N is any nucleotide. ABFI-binding sites were located next to autonomously replicating sequences (ARSs) at controlling elements of the silent mating type loci HMR E, HMR I, and HML I and were associated with ARS1, ARS2, and the 2..mu..m plasmid ARS. Two tandem ABFI binding sites were found between the HIS3 and DED1 genes, several kilobase pairs from any ARS, indicating that ABFI-binding sites are not restricted to ARSs. The sequences recognized by AFBI showed partial dyad-symmetry and appeared to be variations of the consensus 5'-TATCATTNNNNACGA-3'. GRFI and ABFI were both abundant DNA-binding factors and did not appear to be encoded by the SIR genes, whose product are required for repression of the silent mating type loci. Together, these results indicate that both GRFI and ABFI play multiple roles within the cell.« less
Identification of novel alleles of the rice blast resistance gene Pi54

NASA Astrophysics Data System (ADS)

Vasudevan, Kumar; Gruissem, Wilhelm; Bhullar, Navreet K.

2015-10-01

Rice blast is one of the most devastating rice diseases and continuous resistance breeding is required to control the disease. The rice blast resistance gene Pi54 initially identified in an Indian cultivar confers broad-spectrum resistance in India. We explored the allelic diversity of the Pi54 gene among 885 Indian rice genotypes that were found resistant in our screening against field mixture of naturally existing M. oryzae strains as well as against five unique strains. These genotypes are also annotated as rice blast resistant in the International Rice Genebank database. Sequence-based allele mining was used to amplify and clone the Pi54 allelic variants. Nine new alleles of Pi54 were identified based on the nucleotide sequence comparison to the Pi54 reference sequence as well as to already known Pi54 alleles. DNA sequence analysis of the newly identified Pi54 alleles revealed several single polymorphic sites, three double deletions and an eight base pair deletion. A SNP-rich region was found between a tyrosine kinase phosphorylation site and the nucleotide binding site (NBS) domain. Together, the newly identified Pi54 alleles expand the allelic series and are candidates for rice blast resistance breeding programs.

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