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  1 / 103 MEDLINE  
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[PMID]:28902910
[Au] Autor:Li Q; Hegge R; Bridges PJ; Matthews JC
[Ad] Endereço:Department of Animal and Food Sciences, University of Kentucky, Lexington, Kentucky, United States of America.
[Ti] Título:Pituitary genomic expression profiles of steers are altered by grazing of high vs. low endophyte-infected tall fescue forages.
[So] Source:PLoS One;12(9):e0184612, 2017.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Consumption of ergot alkaloid-containing tall fescue grass impairs several metabolic, vascular, growth, and reproductive processes in cattle, collectively producing a clinical condition known as "fescue toxicosis." Despite the apparent association between pituitary function and these physiological parameters, including depressed serum prolactin; no reports describe the effect of fescue toxicosis on pituitary genomic expression profiles. To identify candidate regulatory mechanisms, we compared the global and selected targeted mRNA expression patterns of pituitaries collected from beef steers that had been randomly assigned to undergo summer-long grazing (89 to 105 d) of a high-toxic endophyte-infected tall fescue pasture (HE; 0.746 µg/g ergot alkaloids; 5.7 ha; n = 10; BW = 267 ± 14.5 kg) or a low-toxic endophyte tall fescue-mixed pasture (LE; 0.023 µg/g ergot alkaloids; 5.7 ha; n = 9; BW = 266 ± 10.9 kg). As previously reported, in the HE steers, serum prolactin and body weights decreased and a potential for hepatic gluconeogenesis from amino acid-derived carbons increased. In this manuscript, we report that the pituitaries of HE steers had 542 differentially expressed genes (P < 0.001, false discovery rate ≤ 4.8%), and the pattern of altered gene expression was dependent (P < 0.001) on treatment. Integrated Pathway Analysis revealed that canonical pathways central to prolactin production, secretion, or signaling were affected, in addition to those related to corticotropin-releasing hormone signaling, melanocyte development, and pigmentation signaling. Targeted RT-PCR analysis corroborated these findings, including decreased (P < 0.05) expression of DRD2, PRL, POU1F1, GAL, and VIP and that of POMC and PCSK1, respectively. Canonical pathway analysis identified HE-dependent alteration in signaling of additional pituitary-derived hormones, including growth hormone and GnRH. We conclude that consumption of endophyte-infected tall fescue alters the pituitary transcriptome profiles of steers in a manner consistent with their negatively affected physiological parameters.
[Mh] Termos MeSH primário: Doenças dos Bovinos/genética
Epichloe/fisiologia
Alcaloides de Claviceps/toxicidade
Lolium/microbiologia
Transcriptoma
[Mh] Termos MeSH secundário: Animais
Bovinos
Doenças dos Bovinos/metabolismo
Doenças dos Bovinos/microbiologia
Comportamento Alimentar
Redes Reguladoras de Genes
Hipófise/metabolismo
Prolactina/biossíntese
Prolactina/secreção
RNA Mensageiro/genética
RNA Mensageiro/metabolismo
Reação em Cadeia da Polimerase em Tempo Real
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Ergot Alkaloids); 0 (RNA, Messenger); 9002-62-4 (Prolactin)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171024
[Lr] Data última revisão:
171024
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170914
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0184612


  2 / 103 MEDLINE  
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[PMID]:28886068
[Au] Autor:Clayton W; Eaton CJ; Dupont PY; Gillanders T; Cameron N; Saikia S; Scott B
[Ad] Endereço:Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand.
[Ti] Título:Analysis of simple sequence repeat (SSR) structure and sequence within Epichloë endophyte genomes reveals impacts on gene structure and insights into ancestral hybridization events.
[So] Source:PLoS One;12(9):e0183748, 2017.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Epichloë grass endophytes comprise a group of filamentous fungi of both sexual and asexual species. Known for the beneficial characteristics they endow upon their grass hosts, the identification of these endophyte species has been of great interest agronomically and scientifically. The use of simple sequence repeat loci and the variation in repeat elements has been used to rapidly identify endophyte species and strains, however, little is known of how the structure of repeat elements changes between species and strains, and where these repeat elements are located in the fungal genome. We report on an in-depth analysis of the structure and genomic location of the simple sequence repeat locus B10, commonly used for Epichloë endophyte species identification. The B10 repeat was found to be located within an exon of a putative bZIP transcription factor, suggesting possible impacts on polypeptide sequence and thus protein function. Analysis of this repeat in the asexual endophyte hybrid Epichloë uncinata revealed that the structure of B10 alleles reflects the ancestral species that hybridized to give rise to this species. Understanding the structure and sequence of these simple sequence repeats provides a useful set of tools for readily distinguishing strains and for gaining insights into the ancestral species that have undergone hybridization events.
[Mh] Termos MeSH primário: Epichloe/genética
Repetições de Microssatélites/genética
[Mh] Termos MeSH secundário: Endófitos/genética
Genoma/genética
Hibridização Genética/genética
Peptídeos/genética
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Peptides)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171016
[Lr] Data última revisão:
171016
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170909
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0183748


  3 / 103 MEDLINE  
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[PMID]:28515076
[Au] Autor:Gundel PE; Rudgers JA; Whitney KD
[Ad] Endereço:IFEVA, Universidad de Buenos Aires, CONICET, Facultad de Agronomía, Buenos Aires, Argentina gundel@agro.uba.ar.
[Ti] Título:Vertically transmitted symbionts as mechanisms of transgenerational effects.
[So] Source:Am J Bot;104(5):787-792, 2017 May.
[Is] ISSN:1537-2197
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:PREMISE OF THE STUDY: A transgenerational effect occurs when a biotic or abiotic environmental factor acts on a parental individual and thereby affects the phenotype of progeny. Due to the importance of transgenerational effects for understanding plant ecology and evolution, their underlying mechanisms are of general interest. Here, we introduce the concept that inherited symbiotic microorganisms could act as mechanisms of transgenerational effects in plants. METHODS: We define the criteria required to demonstrate that transgenerational effects are microbially mediated and review evidence from the well-studied, vertically transmitted plant-fungal symbiosis (grass- spp.) in support of such effects. We also propose a basic experimental design to test for the presence of adaptive transgenerational effects mediated by plant symbionts. KEY RESULTS: An increasingly large body of literature shows that vertically transmitted microorganisms are common in plants, with potential to affect the phenotypes and fitness of progeny. Transgenerational effects could occur via parental modification of symbiont presence/absence, symbiont load, symbiont products, symbiont genotype or species composition, or symbiont priming. Several of these mechanisms appear likely in the grass- endophytic symbiosis, as there is variation in the proportion of the progeny that carries the fungus, as well as variation in concentrations of mycelia and secondary compounds (alkaloids and osmolytes) in the seed. CONCLUSIONS: Symbiont-mediated transgenerational effects could be common in plants and could play large roles in plant adaptation to changing environments, but definitive tests are needed. We hope our contribution will spark new lines of research on the transgenerational effects of vertically transmitted symbionts in plants.
[Mh] Termos MeSH primário: Epichloe
Poaceae/microbiologia
Simbiose
[Mh] Termos MeSH secundário: Endófitos
Genótipo
Fenótipo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171019
[Lr] Data última revisão:
171019
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170519
[St] Status:MEDLINE
[do] DOI:10.3732/ajb.1700036


  4 / 103 MEDLINE  
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[PMID]:28411211
[Au] Autor:Cheplick GP
[Ad] Endereço:Department of Biology, College of Staten Island, City University of New York, Staten Island, New York 10314 USA gregory.cheplick@csi.cuny.edu.
[Ti] Título:Persistence of endophytic fungi in cultivars of grown from seeds stored for 22 years.
[So] Source:Am J Bot;104(4):627-631, 2017 Apr.
[Is] ISSN:1537-2197
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:PREMISE OF THE STUDY: Genetic resources for forage crops often consist of seeds of specific species and cultivars in cold storage for future use in breeding and selection programs. Temperate grasses such as , used worldwide for forage and turf, produce seeds commonly infected by hyphae of an endophytic fungus ( var. ). This research determined whether endophytes could persist and infect seedlings of emerging from seeds stored for over two decades. METHODS: Endophyte-infected seeds (>90% infected) of four cultivars were obtained in 1994 and stored dry in plastic bags at 4°C. Seed germination was tested after 12 yr (for two cultivars) and after 18 and 22 yr (for all cultivars). Seedling leaf sheaths were excised, stained, and examined at 400× for endophytic hyphae to quantify infection frequency (% plants infected) and intensity (mean number of endophytic hyphae per field of view). KEY RESULTS: Seed germination after 22 yr depended on cultivar, ranging from 53 to 78%. Between 58 and 73% of plants grown from seeds stored for 22 yr still contained viable endophytic hyphae. Infection intensity remained at original levels for 18 yr in one cultivar; however, in all cultivars, infection intensity declined significantly between 18 and 22 yr. CONCLUSIONS: Persistence of the grass seed-endophyte symbiosis for over 20 yr surpasses all prior records of endophyte longevity within stored seeds. Storage of germplasm of cool-season grass cultivars that contain potentially beneficial fungal endophytes should be possible for several decades under dry, cold conditions.
[Mh] Termos MeSH primário: Endófitos/fisiologia
Epichloe/fisiologia
Lolium/microbiologia
Sementes/microbiologia
[Mh] Termos MeSH secundário: Germinação
Fatores de Tempo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1708
[Cu] Atualização por classe:170822
[Lr] Data última revisão:
170822
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170416
[St] Status:MEDLINE
[do] DOI:10.3732/ajb.1700030


  5 / 103 MEDLINE  
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[PMID]:28334408
[Au] Autor:Bell-Dereske L; Takacs-Vesbach C; Kivlin SN; Emery SM; Rudgers JA
[Ad] Endereço:Department of Biology, 1 University of New Mexico, Albuquerque, NM 87131, USA.
[Ti] Título:Leaf endophytic fungus interacts with precipitation to alter belowground microbial communities in primary successional dunes.
[So] Source:FEMS Microbiol Ecol;93(6), 2017 Jun 01.
[Is] ISSN:1574-6941
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:Understanding interactions between above- and belowground components of ecosystems is an important next step in community ecology. These interactions may be fundamental to predicting ecological responses to global change because indirect effects occurring through altered species interactions can outweigh or interact with the direct effects of environmental drivers. In a multiyear field experiment (2010-2015), we tested how experimental addition of a mutualistic leaf endophyte (Epichloë amarillans) associated with American beachgrass (Ammophila breviligulata) interacted with an altered precipitation regime (±30%) to affect the belowground microbial community. Epichloë addition increased host root biomass at the plot scale, but reduced the length of extraradical arbuscular mycorrhizal (AM) fungal hyphae in the soil. Under ambient precipitation alone, the addition of Epichloë increased root biomass per aboveground tiller and reduced the diversity of AM fungi in A. breviligulata roots. Furthermore, with Epichloë added, the diversity of root-associated bacteria declined with higher soil moisture, whereas in its absence, bacterial diversity increased with higher soil moisture. Thus, the aboveground fungal mutualist not only altered the abundance and composition of belowground microbial communities but also affected how belowground communities responded to climate, suggesting that aboveground microbes have potential for cascading influences on community dynamics and ecosystem processes that occur belowground.
[Mh] Termos MeSH primário: Bactérias/classificação
Endófitos/fisiologia
Epichloe/crescimento & desenvolvimento
Folhas de Planta/microbiologia
Raízes de Plantas/microbiologia
Poaceae/microbiologia
[Mh] Termos MeSH secundário: Biodiversidade
Biomassa
Biota
Ecossistema
Meio Ambiente
Micorrizas/fisiologia
Solo
Microbiologia do Solo
Simbiose/fisiologia
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Soil)
[Em] Mês de entrada:1711
[Cu] Atualização por classe:171116
[Lr] Data última revisão:
171116
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170324
[St] Status:MEDLINE
[do] DOI:10.1093/femsec/fix036


  6 / 103 MEDLINE  
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[PMID]:28315955
[Au] Autor:Perez LI; Gundel PE; Marrero HJ; Arzac AG; Omacini M
[Ad] Endereço:IFEVA-Facultad de Agronomía (UBA)/CONICET, Cátedra de Ecología, Av. San Martín 4453, C1417DSE, Buenos Aires, Argentina. liperez@agro.uba.ar.
[Ti] Título:Symbiosis with systemic fungal endophytes promotes host escape from vector-borne disease.
[So] Source:Oecologia;184(1):237-245, 2017 May.
[Is] ISSN:1432-1939
[Cp] País de publicação:Germany
[La] Idioma:eng
[Ab] Resumo:Plants interact with a myriad of microorganisms that modulate their interactions within the community. A well-described example is the symbiosis between grasses and Epichloë fungal endophytes that protects host plants from herbivores. It is suggested that these symbionts could play a protective role for plants against pathogens through the regulation of their growth and development and/or the induction of host defences. However, other endophyte-mediated ecological mechanisms involved in disease avoidance have been scarcely explored. Here we studied the endophyte impact on plant disease caused by the biotrophic fungus, Claviceps purpurea, under field conditions through (1) changes in the survival of the pathogen´s resistance structure (sclerotia) during overwintering on the soil surface, and (2) effects on insects responsible for the transportation of pathogen spores. This latter mechanism is tested through a visitor exclusion treatment and the measurement of plant volatile cues. We found no significant effects of the endophyte on the survival of sclerotia and thus on disease inocula. However, both pathogen incidence and severity were twofold lower in endophyte-symbiotic plants than in non-symbiotic ones, though when insect visits were prevented this difference disappeared. Endophyte-symbiotic and non-symbiotic plots presented different emission patterns of volatiles suggesting that they can play a role in this protection. We show a novel indirect ecological mechanism by which endophytes can defend host grasses against diseases through negatively interacting with intermediary vectors of the epidemic process.
[Mh] Termos MeSH primário: Endófitos
Simbiose
[Mh] Termos MeSH secundário: Animais
Epichloe
Herbivoria
Poaceae/microbiologia
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1705
[Cu] Atualização por classe:171010
[Lr] Data última revisão:
171010
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170320
[St] Status:MEDLINE
[do] DOI:10.1007/s00442-017-3850-3


  7 / 103 MEDLINE  
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[PMID]:28017692
[Au] Autor:Rahnama M; Forester N; Ariyawansa KG; Voisey CR; Johnson LJ; Johnson RD; Fleetwood DJ
[Ad] Endereço:AgResearch, Grasslands Research Centre, Palmerston North, New Zealand; School of Biological Sciences, University of Auckland, New Zealand.
[Ti] Título:Efficient targeted mutagenesis in Epichloë festucae using a split marker system.
[So] Source:J Microbiol Methods;134:62-65, 2017 Mar.
[Is] ISSN:1872-8359
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:A split-marker system for targeted gene deletion was developed for the model grass endophytic fungus Epichloë festucae. Compared to the conventional system that yields up to 25% homologous recombinants, the method resulted in 33-74% targeted deletions in E. festucae using as little as 1.5kb of targeting sequence.
[Mh] Termos MeSH primário: Clonagem Molecular/métodos
Epichloe/genética
Proteínas Fúngicas/genética
Deleção de Genes
Mutagênese
[Mh] Termos MeSH secundário: Vetores Genéticos
Filogenia
Reação em Cadeia da Polimerase
Recombinação Genética
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Fungal Proteins)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170522
[Lr] Data última revisão:
170522
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161227
[St] Status:MEDLINE


  8 / 103 MEDLINE  
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[PMID]:27882646
[Au] Autor:Green KA; Becker Y; Tanaka A; Takemoto D; Fitzsimons HL; Seiler S; Lalucque H; Silar P; Scott B
[Ad] Endereço:Institute of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand.
[Ti] Título:SymB and SymC, two membrane associated proteins, are required for Epichloë festucae hyphal cell-cell fusion and maintenance of a mutualistic interaction with Lolium perenne.
[So] Source:Mol Microbiol;103(4):657-677, 2017 Feb.
[Is] ISSN:1365-2958
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:Cell-cell fusion in fungi is required for colony formation, nutrient transfer and signal transduction. Disruption of genes required for hyphal fusion in Epichloë festucae, a mutualistic symbiont of Lolium grasses, severely disrupts the host interaction phenotype. They examined whether symB and symC, the E. festucae homologs of Podospora anserina self-signaling genes IDC2 and IDC3, are required for E. festucae hyphal fusion and host symbiosis. Deletion mutants of these genes were defective in hyphal cell fusion, formed intra-hyphal hyphae, and had enhanced conidiation. SymB-GFP and SymC-mRFP1 localize to plasma membrane, septa and points of hyphal cell fusion. Plants infected with ΔsymB and ΔsymC strains were severely stunted. Hyphae of the mutants colonized vascular bundles, were more abundant than wild type in the intercellular spaces and formed intra-hyphal hyphae. Although these phenotypes are identical to those previously observed for cell wall integrity MAP kinase mutants no difference was observed in the basal level of MpkA phosphorylation or its cellular localization in the mutant backgrounds. Both genes contain binding sites for the transcription factor ProA. Collectively these results show that SymB and SymC are key components of a conserved signaling network for E. festucae to maintain a mutualistic symbiotic interaction within L. perenne.
[Mh] Termos MeSH primário: Epichloe/genética
Proteínas Fúngicas/genética
Hifas/genética
Lolium/crescimento & desenvolvimento
Proteínas de Membrana/genética
Esporos Fúngicos/crescimento & desenvolvimento
Simbiose/genética
[Mh] Termos MeSH secundário: Fusão Celular
Epichloe/fisiologia
Proteínas Fúngicas/metabolismo
Regulação Fúngica da Expressão Gênica
Hifas/fisiologia
Lolium/microbiologia
Proteínas de Membrana/metabolismo
Proteínas Quinases Ativadas por Mitógeno/genética
Proteínas Quinases Ativadas por Mitógeno/metabolismo
Fosforilação
Regiões Promotoras Genéticas/genética
Ligação Proteica/genética
Deleção de Sequência/genética
Esporos Fúngicos/genética
Fatores de Transcrição/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Fungal Proteins); 0 (Membrane Proteins); 0 (Transcription Factors); EC 2.7.11.24 (Mitogen-Activated Protein Kinases)
[Em] Mês de entrada:1708
[Cu] Atualização por classe:170816
[Lr] Data última revisão:
170816
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161125
[St] Status:MEDLINE
[do] DOI:10.1111/mmi.13580


  9 / 103 MEDLINE  
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[PMID]:27846291
[Au] Autor:Dirihan S; Helander M; Väre H; Gundel PE; Garibaldi LA; Irisarri JG; Saloniemi I; Saikkonen K
[Ad] Endereço:Department of Biology, University of Turku, Turku, Finland.
[Ti] Título:Geographic Variation in Festuca rubra L. Ploidy Levels and Systemic Fungal Endophyte Frequencies.
[So] Source:PLoS One;11(11):e0166264, 2016.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Polyploidy and symbiotic Epichloë fungal endophytes are common and heritable characteristics that can facilitate environmental range expansion in grasses. Here we examined geographic patterns of polyploidy and the frequency of fungal endophyte colonized plants in 29 Festuca rubra L. populations from eight geographic sites across latitudes from Spain to northernmost Finland and Greenland. Ploidy seemed to be positively and negatively correlated with latitude and productivity, respectively. However, the correlations were nonlinear; 84% of the plants were hexaploids (2n = 6x = 42), and the positive correlation between ploidy level and latitude is the result of only four populations skewing the data. In the southernmost end of the gradient 86% of the plants were tetraploids (2n = 4x = 28), whereas in the northernmost end of the gradient one population had only octoploid plants (2n = 8x = 56). Endophytes were detected in 22 out of the 29 populations. Endophyte frequencies varied among geographic sites, and populations and habitats within geographic sites irrespective of ploidy, latitude or productivity. The highest overall endophyte frequencies were found in the southernmost end of the gradient, Spain, where 69% of plants harbored endophytes. In northern Finland, endophytes were detected in 30% of grasses but endophyte frequencies varied among populations from 0% to 75%, being higher in meadows compared to riverbanks. The endophytes were detected in 36%, 30% and 27% of the plants in Faroe Islands, Iceland and Switzerland, respectively. Practically all examined plants collected from southern Finland and Greenland were endophyte-free, whereas in other geographic sites endophyte frequencies were highly variable among populations. Common to all populations with high endophyte frequencies is heavy vertebrate grazing. We propose that the detected endophyte frequencies and ploidy levels mirror past distribution history of F. rubra after the last glaciation period, and local adaptations to past or prevailing selection forces such as vertebrate grazing.
[Mh] Termos MeSH primário: Endófitos/genética
Epichloe/genética
Festuca/genética
Ploidias
[Mh] Termos MeSH secundário: Dinamarca
Ecossistema
Endófitos/crescimento & desenvolvimento
Epichloe/crescimento & desenvolvimento
Festuca/crescimento & desenvolvimento
Festuca/microbiologia
Finlândia
Genética Populacional
Islândia
Espanha
Suíça
Simbiose/genética
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1706
[Cu] Atualização por classe:170621
[Lr] Data última revisão:
170621
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161116
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0166264


  10 / 103 MEDLINE  
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[PMID]:27669299
[Au] Autor:Klotz JL; Aiken GE; Bussard JR; Foote AP; Harmon DL; Goff BM; Schrick FN; Strickland JR
[Ad] Endereço:USDA-ARS, Forage-Animal Production Research Unit, Lexington, KY 40546, USA. james.klotz@ars.usda.gov.
[Ti] Título:Vasoactivity and Vasoconstriction Changes in Cattle Related to Time off Toxic Endophyte-Infected Tall Fescue.
[So] Source:Toxins (Basel);8(10), 2016 09 22.
[Is] ISSN:2072-6651
[Cp] País de publicação:Switzerland
[La] Idioma:eng
[Ab] Resumo:Previous research has indicated that serotonergic and α-adrenergic receptors in peripheral vasculature are affected by exposure of cattle grazing toxic endophyte-infected (E+; Epichlöe coenophialia) tall fescue (Lolium arundinaceum). The objective of this experiment was to determine the period of time necessary for the vascular effects of ergot alkaloids to subside. Two experiments were conducted to investigate changes in vascular contractile response and vasoconstriction over time relative to removal from an ergot alkaloid-containing E+ tall fescue pasture. In Experiment 1, lateral saphenous vein biopsies were conducted on 21 predominantly Angus steers (357 ± 3 kg body weight) at 0 (n = 6), 7 (n = 6), 14 (n = 5), or 28 days (n = 4) after removal from grazing pasture (3.0 ha; endpoint ergovaline + ergovalinine = 1.35 mg/kg DM) for 126 days. In Experiment 2, lateral saphenous veins were biopsied from 24 Angus-cross steers (361 ± 4 kg body weight) at 0, 21, 42, and 63 days (n = 6 per time point) following removal from grazing tall fescue pastures (3.0 ha; first 88 days endpoint ergovaline + ergovalinine = 0.15 mg/kg DM; last 18 days endpoint ergovaline + ergovalinine = 0.57 mg/kg DM) for 106 total days. Six steers (370 ± 18 kg body weight) off of bermudagrass pasture for the same time interval were also biopsied on Day 0 and Day 63 (n = 3 per time point). Additionally, in Experiment 2, cross-sectional ultrasound scans of caudal artery at the fourth coccygeal vertebra were taken on Days 0, 8, 15, 21, 29, 36, 42, and 45 to determine mean artery luminal area to evaluate vasoconstriction. In both experiments, steers were removed from pasture and housed in a dry lot and fed a corn silage diet for the duration of biopsies and ultrasound scans. Biopsied vessels used to evaluate vasoactivity were cleaned, incubated in a multimyograph, and exposed to increasing concentrations of 4-Bromo-3,6-dimethoxybenzocyclobuten-1-yl) methylamine hydrobromide (TCB2; 5HT2A agonist), guanfacine (GF; α2A-adrenergic agonist), and (R)-(+)-m-nitrobiphenyline oxalate (NBP; α2C-adrenergic agonist) in both experiments and ergovaline (ERV) and ergotamine (ERT) in Experiments 1 and 2, respectively. In Experiment 1, days off pasture × agonist concentration was not significant (p > 0.1) for all four compounds tested. In Experiment 2, GF, NBP, TCB2 and ERT were significant for days off pasture × agonist concentration interaction (p < 0.02) and vasoactivity increased over time. Vasoactivity to agonists was reduced (p < 0.05) when steers were initially removed from E+ tall fescue pasture compared to bermudagrass, but did not differ by Day 63 for any variable. Luminal areas of caudal arteries in steers grazed on E+ tall fescue relaxed and were similar to steers that had grazed bermudagrass for 36 days on non-toxic diet (p = 0.15). These data demonstrate changes in peripheral vasoactivity and recovery from vasoconstriction occur beyond five weeks off toxic pasture and 5HT2A receptors appear to be more dramatically affected in the lateral saphenous vein by grazing E+ tall fescue pasture than adrenergic receptors.
[Mh] Termos MeSH primário: Endófitos/fisiologia
Epichloe/fisiologia
Festuca/microbiologia
Veia Safena/fisiologia
[Mh] Termos MeSH secundário: Agonistas de Receptores Adrenérgicos alfa 2/farmacologia
Animais
Compostos Bicíclicos com Pontes/farmacologia
Bovinos
Alcaloides de Claviceps/farmacologia
Comportamento Alimentar
Guanfacina/farmacologia
Masculino
Metilaminas/farmacologia
Prolactina/sangue
Veia Safena/efeitos dos fármacos
Agonistas de Receptores 5-HT2 de Serotonina/farmacologia
Vasoconstrição
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 ((4-bromo-3,6-dimethoxybenzocyclobuten-1-yl)methylamine); 0 (Adrenergic alpha-2 Receptor Agonists); 0 (Bridged Bicyclo Compounds); 0 (Ergot Alkaloids); 0 (Methylamines); 0 (Serotonin 5-HT2 Receptor Agonists); 30OMY4G3MK (Guanfacine); 9002-62-4 (Prolactin)
[Em] Mês de entrada:1711
[Cu] Atualização por classe:171122
[Lr] Data última revisão:
171122
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160927
[St] Status:MEDLINE



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