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1.
Food Microbiol ; 116: 104367, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37689428

RESUMO

Microgreens, the immature plants harvested after a few weeks of growth, are perceived as a heathy, nutritious food ingredient but may be susceptible to colonisation by human pathogens including Shiga-toxigenic Escherichia coli (STEC). Some microgreen cultivars accumulate anthocyanins or secrete essential oils which, when extracted or purified, have been reported to inhibit bacterial growth. Therefore, the impact of anthocyanins on bacterial colonisation by STEC (Sakai) was compared for three species that have pigmented cultivars: basil (Ocimum basilicum L.), cabbage (Brassica oleracea L.) and mustard greens (Brassica juncea L.). Inoculation with low concentrations of STEC (Sakai) (3 log10 colony forming units/ml (CFU/ml)) during seed germination resulted in extensive colonisation at the point of harvest, accumulating to âˆ¼ 8 log10 CFU/g FW in all cultivars. Bacterial colonies frequently aligned with anticlinal walls on the surface of epidermal cells of the cotyledons and, in basil, associated with peltate and capitate gland cells. Crude lysates of pigmented and non-pigmented basil cultivars had no impact on STEC (Sakai) growth rates, viability status or biofilm formation. Anthocyanins are located within plant vacuoles of these microgreen cultivars and did not affect colonisation by STEC (Sakai) and pigmentation therefore cannot be considered as a controlling factor in bacterial interactions.


Assuntos
Antocianinas , Ocimum basilicum , Humanos , Mostardeira , Cotilédone , Pigmentação
2.
Ecology ; 105(6): e4304, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38747119

RESUMO

Increasing ocean temperature will speed up physiological rates of ectotherms. In fish, this is suggested to cause earlier spawning due to faster oocyte growth rates. Over time, this could cause spawning time to become decoupled from the timing of offspring food resources, a phenomenon referred to as trophic asynchrony. We used biological data, including body length, age, and gonad developmental stages collected from >125,000 individual Northeast Arctic cod (Gadus morhua) sampled between 59 and 73° N in 1980-2019. Combined with experimental data on oocyte growth rates, our analyses show that cod spawned progressively earlier by about a week per decade, partly due to ocean warming. It also appears that spawning time varied by more than 40 days, depending on year and spawning location. The significant plasticity in spawning time seems to be fine-tuned to the local phytoplankton spring bloom phenology. This ability to partly overcome thermal drivers and thus modulate spawning time could allow individuals to maximize fitness by closely tracking local environmental conditions important for offspring survival. Our finding highlights a new dimension for trophic match-mismatch and should be an important consideration in models used to predict phenology dynamics in a warmer climate.


Assuntos
Reprodução , Animais , Reprodução/fisiologia , Gadus morhua/fisiologia , Temperatura , Feminino , Fatores de Tempo , Cadeia Alimentar , Mudança Climática , Estações do Ano
3.
Microbiol Resour Announc ; 12(3): e0114822, 2023 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-36853066

RESUMO

The draft genome sequences of three "Candidatus Symbiopectobacterium" isolates that were collected from New Zealand-grown potato tubers represent the first report of this proposed taxon in the Southern Hemisphere. Their symbiosis with insects and nematodes and their presence on plants may lead to new strategies for pest control and crop management.

4.
Mitochondrial DNA B Resour ; 7(5): 897-899, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35692707

RESUMO

We describe the complete mitochondrial genomes of the flapper skate Dipturus intermedius (Parnell 1837) and the longnose skate Dipturus oxyrinchus (Linnaeus 1758), which have been obtained by Sanger sequencing. We report the length of the sequences to be 16,906 and 16,911 bp, respectively. The length and structure of gene regions, containing 13 protein-coding regions, 22 tRNA genes, two rRNA genes, and two non-coding areas, resemble those of related skate species. Despite D. intermedius being considered a cryptic species with D. batis, the full mitogenomes confirm that D. intermedius and D. oxyrinchus are more genetically similar. In comparison to other Dipturus species, D. intermedius is missing a whole codon in its cytochrome oxidase subunit 2 gene. These mitogenomes will be a useful resource furthering investigation of the population genetic differences and evolutionary history of skate species.

5.
J Microbiol Methods ; 181: 106132, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33370554

RESUMO

MacConkey broth purple provides a more efficient method for Most Probable Number estimation for Shigatoxigenic Escherichia coli (E.coli) than the process of bacterial enrichment in buffered peptone water followed by detection on MacConkey agar, since it is a single-step process that gives comparable results in plant extracts.


Assuntos
Meios de Cultura , Infecções por Escherichia coli/microbiologia , Microbiologia de Alimentos/métodos , Escherichia coli Shiga Toxigênica/isolamento & purificação , Microbiologia da Água , Animais , Humanos
6.
Commun Biol ; 3(1): 690, 2020 11 19.
Artigo em Inglês | MEDLINE | ID: mdl-33214649

RESUMO

Understanding life stage connectivity is essential to define appropriate spatial scales for fisheries management and develop effective strategies to reduce undersized bycatch. Despite many studies of population structure and connectivity in marine fish, most management units do not reflect biological populations and protection is rarely given to juvenile sources of the fished stock. Direct, quantitative estimates that link specific fishing grounds to the nursery areas, which produced the caught fish are essential to meet these objectives. Here we develop a continuous-surface otolith microchemistry approach to geolocate whiting (Merlangius merlangus) and infer life stage connectivity across the west coast of the UK. We show substantial connectivity across existing stock boundaries and identify the importance of the Firth of Clyde nursery area. This approach offers fisheries managers the ability to account for the benefits of improved fishing yields derived from spatial protection while minimising revenue loss.


Assuntos
Ecossistema , Pesqueiros , Gadiformes/fisiologia , Membrana dos Otólitos/química , Animais , Conservação dos Recursos Naturais , Membrana dos Otólitos/fisiologia
7.
PLoS One ; 14(4): e0214459, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30939152

RESUMO

Understanding spatial distributions of fish species is important to those seeking to manage fisheries and advise on marine developments. Distribution patterns, habitat use, and aggregative behaviour often vary throughout the life cycle and can increase the vulnerability of certain life stages to anthropogenic impacts. Here we investigate distribution changes during the life cycle of whiting (Merlangius merlangus) to the west of the UK. Density distributions for age-0, age-1 and mature fish were modelled as functions of environmental variables using generalised additive mixed effects models. The greatest densities of age-0 whiting occurred over finer sediments where temperatures were between 12 to 13°C. Age-0 whiting densities decreased with increasing depth. Higher densities of age-1 whiting were also associated with fine sediments and peaked at 60 m, but this influence was also dependent on proximity to shore. Mature fish, while showing no association with any particular sediment type, were strongly associated with depths >60 m. Geostatistical aggregation curves were used to classify space use and showed persistent aggregations of age-0 whiting occupying inshore waters while age-1 and mature fish were more dispersed and differed among years. The differences in distributions among life stages suggested a general coastal to offshore shift as cohorts developed with mature whiting mainly occupying deep offshore waters. The spatial dynamics and areas of persistent life stage aggregation identified here could enable informed targeting and avoidance of specific age-class whiting to aid bycatch reduction. Given that landing obligation legislation is counterproductive unless it encourages greater fishing selectivity, the ability to avoid this species and undersized individuals would aid conservation measures and fishermen alike.


Assuntos
Conservação dos Recursos Naturais/métodos , Ecossistema , Pesqueiros , Gadiformes/fisiologia , Estágios do Ciclo de Vida , Algoritmos , Animais , Comportamento Animal , Meio Ambiente , Geografia , Dinâmica Populacional , Probabilidade , Temperatura , Reino Unido
8.
Proc Biol Sci ; 275(1642): 1543-8, 2008 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-18397869

RESUMO

Despite recent evidence for sub-stock structuring, North Sea cod are assessed as a single unit. As a consequence, knowledge of sub-stock trends is poor. In particular, there are no recent evaluations of which spawning grounds are active. Here we report results from the first ichthyoplankton survey to cover the whole North Sea. Also, this survey, conducted in 2004, was the first to make extensive use of DNA-based molecular methods to unambiguously identify early developmental stage cod eggs. We compare the findings from the plankton survey with estimated egg production inferred from the distribution of mature cod in contemporaneous trawl surveys. Results from both approaches were in general agreement and showed hot spots of egg production around the southern and eastern edges of the Dogger Bank, in the German Bight, the Moray Firth and to the east of the Shetlands. These areas broadly coincide with known spawning locations from the period 1940 to 1970. We were, however, unable to directly detect significant numbers of cod eggs at the historic spawning ground off Flamborough (northeast coast of England). The results demonstrate that most of the major spawning grounds of cod in the North Sea are still active but that some localized populations may have been reduced to the point where it is now difficult to detect the presence of eggs in the plankton.


Assuntos
Demografia , Pesqueiros/estatística & dados numéricos , Gadus morhua/fisiologia , Comportamento de Retorno ao Território Vital/fisiologia , Animais , Geografia , Mar do Norte , Óvulo/química , Plâncton/química
9.
BJR Case Rep ; 4(1): 20170064, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30363155

RESUMO

The InterStim II (Medtronic, Inc., Minneapolis, MN) sacral nerve stimulator has been approved for MRI scanning of the head only. All other body areas are contraindicated by the manufacturer. This report presents the successful MRI examination of the left hand in a patient with an InterStim II device. Following an assessment of the risks and benefits of proceeding with the scan it was shown that there were minimal additional risks, which could be easily managed with appropriate patient positioning, coil selection and other established techniques. Informed consent was obtained and the scan completed without incident. Following the scan the patient reported full functioning of the device. MRI of the hand is feasible in patients with InterStim II implants using transmit/receive coils with appropriate risk controls in place. Further study of the safety of MRI of other body regions in InterStim II patients is appropriate.

10.
Ecol Evol ; 8(16): 7907-7920, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30250672

RESUMO

Identifying the mechanisms maintaining population structure in marine fish species with more than a single dispersing life stage is challenging because of the difficulty in tracking all life stages. Here, a two-stage otolith microchemistry approach to examining life-stage movement was adopted, tracking a year-class from the juvenile to adult stage and inferring larval sources from clustering, in order to consider the mechanisms maintaining population structuring in North Sea cod. Clustering of near-core chemistry identified four clusters, two of which had either a southern or northern affinity and were similar to juvenile edge chemistry. The other two clusters, common to the central North Sea, had intermediate chemical composition and may have reflected either larval mixing in this region or a lack of geographic heterogeneity in the elemental signature. From the comparison of whole juvenile and the corresponding component of adult otoliths, adults from the southern North Sea mostly recruited from adjacent nursery grounds. In contrast, many adults in the northern North Sea had a juvenile chemistry consistent with the Skagerrak and juveniles from the northern Skagerrak site had a near-core chemistry consistent with the northern North Sea. Similarities in otolith chemistry were consistent with retention of early life stages at a regional level and also juvenile and adult fidelity. The links between the northern North Sea and Skagerrak indicate natal homing, which when considered in the context of genetic evidence is suggestive of philopatry. The approach used here should be useful in exploring the mechanisms underlying population structuring in other species with multiple dispersive life stages and calcified hard parts.

11.
Proc Biol Sci ; 274(1607): 199-207, 2007 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-17035167

RESUMO

Despite increasing threats to the marine environment, only a fraction of the biodiversity of the oceans has been described, owing in part to the widespread occurrence of cryptic species. DNA-based barcoding through screening of an orthologous reference gene has been proposed as a powerful tool to uncover biological diversity in the face of dwindling taxonomic expertise and the limitations of traditional species identification. Although DNA barcoding should be particularly useful in the sea, given the prevalence of marine cryptic species, the link between taxa identified through DNA barcodes and reproductively isolated taxa (biological species) has rarely been explicitly tested. Here, we use an integrated framework comparing breeding compatibility, morphology and mitochondrial (cytochrome c oxidase 1) and nuclear (elongation factor-1-alpha) DNA sequence variation among globally distributed samples of the cosmopolitan marine bryozoan Celleporella hyalina (L.). Our results reveal that C. hyalina comprises numerous deep, mostly allopatric, genetic lineages that are reproductively isolated, yet share very similar morphology, indicating rampant cryptic speciation. The close correspondence between genetic lineages and reproductively isolated taxa in the context of minimal morphological change suggests that DNA barcoding will play a leading role in uncovering the hidden biodiversity of the oceans and that the sole use of morphologically based taxonomy would grossly underestimate the number of marine species.


Assuntos
Briozoários/genética , DNA/genética , Especiação Genética , Variação Genética , Genética Populacional , Filogenia , Análise de Sequência de DNA/métodos , Animais , Sequência de Bases , Teorema de Bayes , Briozoários/anatomia & histologia , Primers do DNA , Complexo IV da Cadeia de Transporte de Elétrons/genética , Modelos Genéticos , Dados de Sequência Molecular , Fator 1 de Elongação de Peptídeos/genética , Reprodução/genética
12.
Novartis Found Symp ; 277: 149-61; discussion 161-3, 251-3, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-17319160

RESUMO

The dengue virus multidomain RNA polymerase NS5 has been observed in the nucleus in mammalian infected cell systems. We previously showed that NS5 nuclear localization is mediated by two nuclear targeting signals within the NS5 interdomain region that are recognized by distinct members of the importin superfamily of intracellular transporters. Intriguingly, we have recently found that NS5 also possesses the ability to be exported from the nucleus by the importin family member CRM1 (exportin 1) both in Vero cells transfected to express NS5, and in dengue virus type 2 infected Vero cells, based on use of the CRM1-specific inhibitor leptomycin B (LMB). LMB treatment of Vero cells resulted in increased nuclear accumulation in both systems, and interestingly in the latter, resulted in an alteration in the kinetics of virus production. Our results imply that subcellular trafficking of NS5 at particular times in the infectious cycle may be central to the kinetics of virus production; perturbing this trafficking may represent a viable approach to develop new antiviral therapeutics.


Assuntos
Núcleo Celular/metabolismo , Vírus da Dengue/metabolismo , Carioferinas/farmacologia , Proteínas não Estruturais Virais/metabolismo , Replicação Viral , Transporte Ativo do Núcleo Celular , Animais , Chlorocebus aethiops , Dengue/metabolismo , Dengue/virologia , Técnica Indireta de Fluorescência para Anticorpo , Sinais de Localização Nuclear , Receptores Citoplasmáticos e Nucleares , Frações Subcelulares , Células Vero , Proteínas não Estruturais Virais/química , Proteína Exportina 1
13.
Resuscitation ; 105: 188-95, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27321577

RESUMO

INTRODUCTION: The aim of the EuReCa ONE study was to determine the incidence, process, and outcome for out of hospital cardiac arrest (OHCA) throughout Europe. METHODS: This was an international, prospective, multi-centre one-month study. Patients who suffered an OHCA during October 2014 who were attended and/or treated by an Emergency Medical Service (EMS) were eligible for inclusion in the study. Data were extracted from national, regional or local registries. RESULTS: Data on 10,682 confirmed OHCAs from 248 regions in 27 countries, covering an estimated population of 174 million. In 7146 (66%) cases, CPR was started by a bystander or by the EMS. The incidence of CPR attempts ranged from 19.0 to 104.0 per 100,000 population per year. 1735 had ROSC on arrival at hospital (25.2%), Overall, 662/6414 (10.3%) in all cases with CPR attempted survived for at least 30 days or to hospital discharge. CONCLUSION: The results of EuReCa ONE highlight that OHCA is still a major public health problem accounting for a substantial number of deaths in Europe. EuReCa ONE very clearly demonstrates marked differences in the processes for data collection and reported outcomes following OHCA all over Europe. Using these data and analyses, different countries, regions, systems, and concepts can benchmark themselves and may learn from each other to further improve survival following one of our major health care events.


Assuntos
Reanimação Cardiopulmonar/estatística & dados numéricos , Serviços Médicos de Emergência/estatística & dados numéricos , Parada Cardíaca Extra-Hospitalar/mortalidade , Idoso , Europa (Continente)/epidemiologia , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Parada Cardíaca Extra-Hospitalar/terapia , Estudos Prospectivos , Sistema de Registros , Análise de Sobrevida
15.
J Biol Chem ; 284(23): 15589-97, 2009 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-19297323

RESUMO

Although all established functions of dengue virus NS5 (nonstructural protein 5) occur in the cytoplasm, its nuclear localization, mediated by dual nuclear localization sequences, is essential for virus replication. Here, we have determined the mechanism by which NS5 can localize in the cytoplasm to perform its role in replication, establishing for the first time that it is able to be exported from the nucleus by the exportin CRM1 and hence can shuttle between the nucleus and cytoplasm. We define the nuclear export sequence responsible to be residues 327-343 and confirm interaction of NS5 and CRM1 by pulldown assay. Significantly, greater nuclear accumulation of NS5 during infection due to CRM1 inhibition coincided with altered kinetics of virus production and decreased induction of the antiviral chemokine interleukin-8. This is the first report of a nuclear export sequence within NS5 for any member of the Flavivirus genus; because of its high conservation within the genus, it may represent a target for the treatment of diseases caused by several medically important flaviviruses.


Assuntos
RNA Polimerases Dirigidas por DNA/genética , Vírus da Dengue/enzimologia , Carioferinas/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Proteínas não Estruturais Virais/fisiologia , Replicação Viral/fisiologia , Aedes , Animais , Linhagem Celular , Chlorocebus aethiops , RNA Polimerases Dirigidas por DNA/metabolismo , Técnica Indireta de Fluorescência para Anticorpo , Glutationa Transferase/genética , Glutationa Transferase/metabolismo , Humanos , Interleucina-8/biossíntese , Interleucina-8/genética , Carioferinas/farmacologia , Rim , Mutagênese Sítio-Dirigida , Transfecção , Células Vero , Proteínas não Estruturais Virais/química , Proteínas não Estruturais Virais/genética , Proteínas Virais/genética , Proteínas Virais/metabolismo , Proteína Exportina 1
16.
J Biol Chem ; 283(28): 19410-21, 2008 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-18469001

RESUMO

The Flavivirus NS5 protein possesses both (guanine-N7)-methyltransferase and nucleoside-2'-O methyltransferase activities required for sequential methylation of the cap structure present at the 5' end of the Flavivirus RNA genome. Seventeen mutations were introduced into the dengue virus type 2 NS5 methyltransferase domain, targeting amino acids either predicted to be directly involved in S-adenosyl-l-methionine binding or important for NS5 conformation and/or charged interactions. The effects of the mutations on (i) (guanine-N7)-methyltransferase and nucleoside-2'-O methyltransferase activities using biochemical assays based on a bacterially expressed NS5 methyltransferase domain and (ii) viral replication using a dengue virus type 2 infectious cDNA clone were examined. Clustered mutations targeting the S-adenosyl-l-methionine binding pocket or an active site residue abolished both methyltransferase activities and viral replication, demonstrating that both methyltransferase activities utilize a single S-adenosyl-l-methionine binding pocket. Substitutions to single amino acids binding S-adenosyl-l-methionine decreased both methyltransferase activities by varying amounts. However, viruses that replicated at wild type levels could be recovered with mutations that reduced both activities by >75%, suggesting that only a threshold level of methyltransferase activity was required for virus replication in vivo. Mutation of residues outside of regions directly involved in S-adenosyl-l-methionine binding or catalysis also affected methyltransferase activity and virus replication. The recovery of viruses containing compensatory second site mutations in the NS5 and NS3 proteins identified regions of the methyltransferase domain important for overall stability of the protein or likely to play a role in virus replication distinct from that of cap methylation.


Assuntos
Vírus da Dengue/enzimologia , Genoma Viral/fisiologia , Metiltransferases/metabolismo , Mutagênese , Proteínas não Estruturais Virais/metabolismo , Replicação Viral/fisiologia , Aedes , Substituição de Aminoácidos , Animais , Sítios de Ligação/genética , Catálise , Chlorocebus aethiops , Vírus da Dengue/genética , Estabilidade Enzimática/fisiologia , Metiltransferases/genética , Mutação de Sentido Incorreto , Estrutura Terciária de Proteína/fisiologia , RNA Viral/genética , RNA Viral/metabolismo , S-Adenosilmetionina/genética , S-Adenosilmetionina/metabolismo , Células Vero , Proteínas não Estruturais Virais/genética
17.
Mol Ecol ; 16(10): 2173-88, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17498239

RESUMO

The marine bryozoan Celleporella hyalina is a species complex composed of many highly divergent and mostly allopatric genetic lineages that are reproductively isolated but share a remarkably similar morphology. One such lineage commonly encrusts macroalgae throughout the NE Atlantic coast. To explore the processes leading to geographical diversification, reproductive isolation and speciation in this taxon, we (i) investigated NE Atlantic C. hyalina mitochondrial DNA phylogeography, and (ii) used breeding trials between geographical isolates to ascertain reproductive isolation. We find that haplotype diversity is geographically variable and there is a strong population structure, with significant isolation by distance. NE Atlantic C. hyalina is structured into two main parapatric lineages that appear to have had independent Pleistocene histories. Range expansions have resulted in two contact zones in Spain and W Ireland. Lineage 1 is found from Ireland to Spain and has low haplotype diversity, with closely related haplotypes, suggesting a recent population expansion into the Irish Sea, S Ireland, S England and Spain. Lineage 2 is found from Iceland to Spain and has high haplotype diversity. Complete reproductive isolation was found between some geographical isolates representing both lineages, whereas it was incomplete or asymmetric between others, suggesting these latter phylogeographical groups probably represent incipient species. The phylogeographical distribution of NE Atlantic C. hyalina does not fall easily into a pattern of southern refugia, and we discuss likely differences between terrestrial and marine system responses to Pleistocene glacial cycles.


Assuntos
Briozoários/genética , Demografia , Especiação Genética , Genética Populacional , Filogenia , Animais , Oceano Atlântico , Sequência de Bases , Teorema de Bayes , Briozoários/fisiologia , Análise por Conglomerados , DNA Mitocondrial/genética , Geografia , Haplótipos/genética , Funções Verossimilhança , Modelos Genéticos , Dados de Sequência Molecular , Dinâmica Populacional , Reprodução/genética , Análise de Sequência de DNA
18.
Traffic ; 8(7): 795-807, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17537211

RESUMO

Dengue virus nonstructural protein 5 (NS5) is a large multifunctional protein with a central role in viral replication. We previously identified two nuclear localization sequences (NLSs) within the central region of dengue virus type-2 (DENV-2) NS5 ('aNLS' and 'bNLS') that are recognized by the importin alpha/beta and importin beta1 nuclear transporters, respectively. Here, we demonstrate the importance of the kinetics of NS5 nuclear localization to virus production for the first time and show that the aNLS is responsible. Site-specific mutations in the bipartite-type aNLS or bNLS region were introduced into a reporter plasmid encoding green fluorescent protein fused to the N-terminus of DENV-2 NS5, as well as into DENV-2 genomic length complementary DNA. Mutation of basic residues in the highly conserved region of the bNLS did not affect nuclear import of NS5. In contrast, mutations in either basic cluster of the aNLS decreased NS5 nuclear accumulation and reduced virus production, with the greatest reduction observed for mutation of the second cluster (K(387)K(388)K(389)); mutagenesis of both clusters abolished NS5 nuclear import and DENV-2 virus production completely. The latter appeared to relate to the impaired ability of virus lacking nuclear-localizing NS5, as compared with wild-type virus expressing nuclear-localizing NS5, to reduce interleukin-8 production as part of the antiviral response. The results overall indicate that NS5 nuclear localization through the aNLS is integral to viral infection, with significant implications for other flaviviruses of medical importance, such as yellow fever and West Nile viruses.


Assuntos
Núcleo Celular/metabolismo , Proteínas não Estruturais Virais/biossíntese , Proteínas não Estruturais Virais/química , Viroses/metabolismo , alfa Carioferinas/metabolismo , beta Carioferinas/metabolismo , Transporte Ativo do Núcleo Celular , Sequência de Aminoácidos , Animais , Antivirais/farmacologia , Chlorocebus aethiops , Humanos , Dados de Sequência Molecular , Sinais de Localização Nuclear , Homologia de Sequência de Aminoácidos , Células Vero , Proteínas não Estruturais Virais/metabolismo
19.
J Biol Chem ; 282(14): 10678-89, 2007 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-17287213

RESUMO

Viruses of the family Flaviviridae are important human and animal pathogens. Among them, the Flaviviruses dengue (DENV) and West Nile (WNV) cause regular outbreaks with fatal outcomes. The RNA-dependent RNA polymerase (RdRp) activity of the non-structural protein 5 (NS5) is a key activity for viral RNA replication. In this study, crystal structures of enzymatically active and inactive WNV RdRp domains were determined at 3.0- and 2.35-A resolution, respectively. The determined structures were shown to be mostly similar to the RdRps of the Flaviviridae members hepatitis C and bovine viral diarrhea virus, although with unique elements characteristic for the WNV RdRp. Using a reverse genetic system, residues involved in putative interactions between the RNA-cap methyltransferase (MTase) and the RdRp domain of Flavivirus NS5 were identified. This allowed us to propose a model for the structure of the full-length WNV NS5 by in silico docking of the WNV MTase domain (modeled from our previously determined structure of the DENV MTase domain) onto the RdRp domain. The Flavivirus RdRp domain structure determined here should facilitate both the design of anti-Flavivirus drugs and structure-function studies of the Flavivirus replication complex in which the multifunctional NS5 protein plays a central role.


Assuntos
RNA Polimerase Dependente de RNA/química , Proteínas não Estruturais Virais/química , Vírus do Nilo Ocidental/enzimologia , Animais , Cristalografia por Raios X , Vírus da Diarreia Viral Bovina/química , Vírus da Diarreia Viral Bovina/enzimologia , Inibidores Enzimáticos/química , Inibidores Enzimáticos/uso terapêutico , Hepacivirus/química , Hepacivirus/enzimologia , Humanos , Ligação Proteica , Estrutura Terciária de Proteína , RNA Polimerase Dependente de RNA/antagonistas & inibidores , RNA Polimerase Dependente de RNA/metabolismo , Homologia Estrutural de Proteína , Relação Estrutura-Atividade , Proteínas não Estruturais Virais/antagonistas & inibidores , Proteínas não Estruturais Virais/metabolismo , Febre do Nilo Ocidental/tratamento farmacológico , Febre do Nilo Ocidental/enzimologia , tRNA Metiltransferases/metabolismo
20.
J Gen Virol ; 87(Pt 10): 2791-2801, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16963737

RESUMO

To gain insight into the role of cell surface glycosaminoglycans (GAG) in dengue virus (DEN) cell tropism and virulence, DEN-2 mouse brain-adapted vaccine candidate, neurovirulent prototype strain (NGC) and low-passage strain, PUO-218, were passaged in BHK-21 and SW13 cells to isolate variants with high affinity for GAG. Sequence comparisons of parent and passage variants revealed five GAG-binding determinants, which all cluster in a surface-exposed region in domain II of the three-dimensional structure of the DEN envelope protein. Using an infectious cDNA clone of NGC and an NGC/PUO-218 prM-E chimeric clone, it was demonstrated that the GAG-binding determinants augment the specific infectivity for BHK-21 and/or SW13 cells by 10- to 170-fold and in some cases marginally reduce that for Vero cells. This altered cell tropism was due to a greater dependence of the variants on cell surface GAG for attachment/entry, given their increased susceptibility to heparin inhibition. The effect of the GAG-binding determinants on virulence was examined in mice deficient in alpha/beta/gamma interferon responses. High GAG affinity strongly correlated with low neuroinvasiveness due to rapid virus clearance from the blood. It was speculated that this mechanism accounts for the attenuation in primates of some DEN vaccine candidates. Interestingly, the GAG-binding variants did not display marked attenuation of neurovirulence and the opposing effect of enhanced neurovirulence was associated with one determinant (Lys126) already present in mouse brain-adapted NGC. This discrepancy of attenuated neuroinvasiveness and augmented neurovirulence may be reconciled by the existence of different mechanisms of virus dissemination in the brain and in extraneural tissues.


Assuntos
Vírus da Dengue/metabolismo , Vírus da Dengue/patogenicidade , Glicosaminoglicanos/metabolismo , Animais , Linhagem Celular , Chlorocebus aethiops , Cricetinae , Vírus da Dengue/genética , Heparina/metabolismo , Humanos , Camundongos , Camundongos Knockout , Movimento , Mutação , Ligação Proteica , Receptor de Interferon alfa e beta , Receptores de Interferon/genética , Células Vero , Virulência , Receptor de Interferon gama
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