The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
John Stanley - One of the best experts on this subject based on the ideXlab platform.
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replication promiscuity of dna beta satellites associated with monopartite begomoviruses deletion mutagenesis of the ageratum yellow vein virus dna beta satellite localizes sequences involved in replication
Journal of General Virology, 2008Co-Authors: Keith Saunders, Rob W Briddon, John StanleyAbstract:Pseudorecombination studies in Nicotiana benthamiana demonstrate that Ageratum yellow vein virus (AYVV) and Eupatorium yellow vein virus (EpYVV) can functionally interact with DNA-beta satellites associated with AYVV, EpYVV, cotton leaf curl Multan virus (CLCuMV) and honeysuckle yellow vein virus (HYVV). In contrast, CLCuMV shows some specificity in its ability to interact with distinct satellites and HYVV is able to interact only with its own satellite. Using an N. benthamiana leaf disk assay, we have demonstrated that HYVV is unable to trans-replicate other satellites. To investigate the basis of trans-replication compatibility, deletion mutagenesis of AYVV DNA-beta has been used to localize the origin of replication to approximately 360 nt, encompassing the ubiquitous nonanucleotide/stem-loop structure, satellite conserved region (SCR) and part of the intergenic region immediately upstream of the SCR. Additional deletions within this intergenic region have identified a region that is essential for replication. The capacity for DNA-beta satellites to functionally interact with distinct geminivirus species and its implications for disease diversification are discussed.
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The DNA β satellite component associated with ageratum yellow vein disease encodes an essential pathogenicity protein (βC1)
Virology, 2004Co-Authors: Keith Saunders, Alexandra Norman, Sebastien Gucciardo, John StanleyAbstract:Ageratum yellow vein disease (AYVD) is caused by the geminivirus ageratum yellow vein virus (AYVV) and an associated DNA beta satellite. We have mapped a DNA beta transcript to a highly conserved open reading frame (betaC1 ORF). The most abundant transcript 5'-terminus is located 8 bases upstream of the betaC1 ORF putative initiation codon while the transcript terminates at multiple sites downstream from the putative termination codon. Disruption of betaC1 protein expression by the introduction of an internal nonsense codon prevented infection of the AYVV-satellite complex in ageratum and altered the phenotype in Nicotiana benthamiana to that produced by AYVV alone although the mutant was maintained in systemically infected tissues. Modification of the putative initiation codon to a nonsense codon produced an intermediate phenotype in N. benthamiana and a mild yellow vein phenotype in ageratum, suggesting that betaC1 protein expression could be initiated from an alternative site. N. benthamiana plants containing a dimeric DNA beta transgene produced severe developmental abnormalities, vein-greening, and cell proliferation in the vascular bundles. Expression of betaC1 protein from a potato virus X (PVX) vector also induced abnormal plant growth. Our results demonstrate that the satellite encodes at least one protein that plays a major role in symptom development and is essential for disease progression in ageratum, the natural host of the AYVD complex.
Keith Saunders - One of the best experts on this subject based on the ideXlab platform.
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replication promiscuity of dna beta satellites associated with monopartite begomoviruses deletion mutagenesis of the ageratum yellow vein virus dna beta satellite localizes sequences involved in replication
Journal of General Virology, 2008Co-Authors: Keith Saunders, Rob W Briddon, John StanleyAbstract:Pseudorecombination studies in Nicotiana benthamiana demonstrate that Ageratum yellow vein virus (AYVV) and Eupatorium yellow vein virus (EpYVV) can functionally interact with DNA-beta satellites associated with AYVV, EpYVV, cotton leaf curl Multan virus (CLCuMV) and honeysuckle yellow vein virus (HYVV). In contrast, CLCuMV shows some specificity in its ability to interact with distinct satellites and HYVV is able to interact only with its own satellite. Using an N. benthamiana leaf disk assay, we have demonstrated that HYVV is unable to trans-replicate other satellites. To investigate the basis of trans-replication compatibility, deletion mutagenesis of AYVV DNA-beta has been used to localize the origin of replication to approximately 360 nt, encompassing the ubiquitous nonanucleotide/stem-loop structure, satellite conserved region (SCR) and part of the intergenic region immediately upstream of the SCR. Additional deletions within this intergenic region have identified a region that is essential for replication. The capacity for DNA-beta satellites to functionally interact with distinct geminivirus species and its implications for disease diversification are discussed.
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The DNA β satellite component associated with ageratum yellow vein disease encodes an essential pathogenicity protein (βC1)
Virology, 2004Co-Authors: Keith Saunders, Alexandra Norman, Sebastien Gucciardo, John StanleyAbstract:Ageratum yellow vein disease (AYVD) is caused by the geminivirus ageratum yellow vein virus (AYVV) and an associated DNA beta satellite. We have mapped a DNA beta transcript to a highly conserved open reading frame (betaC1 ORF). The most abundant transcript 5'-terminus is located 8 bases upstream of the betaC1 ORF putative initiation codon while the transcript terminates at multiple sites downstream from the putative termination codon. Disruption of betaC1 protein expression by the introduction of an internal nonsense codon prevented infection of the AYVV-satellite complex in ageratum and altered the phenotype in Nicotiana benthamiana to that produced by AYVV alone although the mutant was maintained in systemically infected tissues. Modification of the putative initiation codon to a nonsense codon produced an intermediate phenotype in N. benthamiana and a mild yellow vein phenotype in ageratum, suggesting that betaC1 protein expression could be initiated from an alternative site. N. benthamiana plants containing a dimeric DNA beta transgene produced severe developmental abnormalities, vein-greening, and cell proliferation in the vascular bundles. Expression of betaC1 protein from a potato virus X (PVX) vector also induced abnormal plant growth. Our results demonstrate that the satellite encodes at least one protein that plays a major role in symptom development and is essential for disease progression in ageratum, the natural host of the AYVD complex.
Michelle Letarte - One of the best experts on this subject based on the ideXlab platform.
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endoglin is a component of the transforming growth factor beta receptor system in human endothelial cells
Journal of Biological Chemistry, 1992Co-Authors: Sela Cheifetz, Carmela Cales, Sonia Vera, Joan Massagué, Carmelo Bernabeu, Teresa Bellon, Michelle LetarteAbstract:Abstract Endoglin, a dimeric membrane glycoprotein expressed at high levels on human vascular endothelial cells, shares regions of sequence identity with betaglycan, a major binding protein for transforming growth factor-beta (TGF-beta) that co-exists with TGF-beta receptors I and II in a variety of cell lines but is low or absent in endothelial cells. We have examined whether endoglin also binds TGF-beta and demonstrate here that the major TGF-beta 1-binding protein co-existing with TGF-beta receptors I and II on human umbilical vein endothelial cells is endoglin, as determined by specific immunoprecipitation of endoglin affinity-labeled with 125I-TGF-beta. Furthermore, endoglin ectopically expressed in COS cells binds TGF-beta 1. Competition affinity-labeling experiments showed that endoglin binds TGF-beta 1 (KD approximately 50 pM) and TGF-beta 3 with high affinity but fails to bind TGF-beta 2. This difference in affinity of endoglin for the TGF-beta isoforms is in contrast to beta-glycan which recognizes all three isoforms. TGF-beta however is binding with high affinity to only a small fraction of the available endoglin molecules, suggesting that some rate-limiting event is required to sustain TGF-beta binding to endoglin.
Rosanna Apa - One of the best experts on this subject based on the ideXlab platform.
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nicotine and cotinine affect the release of vasoactive factors by trophoblast cells and human umbilical vein endothelial cells
Placenta, 2011Co-Authors: Federica Romani, Antonio Lanzone, Anna Tropea, Federica Tiberi, Stefania Catino, Rosanna ApaAbstract:Abstract Objective To examine nicotine (N) and cotinine (C) effects on trophoblast cells (TCs) and human umbilical vein endothelial cells (HUVEC) secretion of soluble fms-like tyrosine kinase (sFlt-1), soluble endoglin (sENG), placental growth factor (PlGF), transforming growth factor-beta (TGF-beta) and vascular endothelial growth factor (VEGF). Study design Human placentas and umbilical cords were collected from uncomplicated pregnancies at term from a total of 24 non-smoking women with a history of normal blood pressure. TCs and HUVEC were cultured for 24 h with C or N (from 10 −12 to 10 −7 M). Main outcome measures sFlt-1, sENG, PlGF, TGF-beta and VEGF release and messenger RNA (mRNA) expression were evaluated by ELISA and real-time polymerase chain reaction (PCR), respectively. Results N and C reduced sFlt-1, sENG and PlGF release by TCs and TGF-beta release by HUVEC. Conversely, N and C increased PlGF secretion, while N alone increased sFlt-1 release by HUVEC. N and C were able to modulate VEGF mRNA expression in HUVEC. Conclusions Our results suggest that N and C affect the balance of some important vasoactive factors released by TCs and HUVEC. This might be one of the possible mechanism through which smoke reduces the risk of hypertensive disorders during pregnancy as well as contributes to the well known detrimental effects of smoking on fetal development.
Ariane Maria Leoni - One of the best experts on this subject based on the ideXlab platform.
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Protein hydrophobic dressing on seeds aiming at the delay of undesirable germination
Scientia Agricola, 2009Co-Authors: Odilio B.g. De Assis, Ariane Maria LeoniAbstract:Polymer seed-coatings have been largely tested as an alternative method for preventing diseases and have the potential to be used to control undesirable germination and thereby increasing seed storage. Amongst these, the protein-based coatings can be applied with advantage of forming stable biodegradable and hydrophobic films. Due to their chemical structure, protein dressings act as efficient barriers for water uptake, even when seeds are unavoidable exposed to a moist environment. In this work, the effect of hydrophobic dressings was tested on the germination rate of sugar beet (Beta vulgaris L.) and broccolis (Brassica oleraceae var italic L.) seeds under laboratorial condition. Zein, natural maize (Zea mays L.) proteins extracted from gluten meal, was used as precursor polymers to form the coatings. Seeds were dressed by direct submersion into a zein/ethanol formulation of zein concentration of 3.0 g L-1, followed by natural air drying. The resultant coating has elevated the hydrophobic feature due to the high content amino acids present in the structure of the zein. For both types of seeds an overall delay in sprouting and germination was observed, with a more accentuated reduction on sugar beet germination percentage after eleven days of measurements. The effect on germination rates is understood as the efficiency of the zein coating to form a physical barrier preventing water permeation into the seeds.
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Protein hydrophobic dressing on seeds aiming at the delay of undesirable germination Cobertura hidrofóbica a base de proteínas sobre sementes visando a redução de germinações indesejáveis
Universidade de São Paulo, 2009Co-Authors: Odilio B.g. De Assis, Ariane Maria LeoniAbstract:Polymer seed-coatings have been largely tested as an alternative method for preventing diseases and have the potential to be used to control undesirable germination and thereby increasing seed storage. Amongst these, the protein-based coatings can be applied with advantage of forming stable biodegradable and hydrophobic films. Due to their chemical structure, protein dressings act as efficient barriers for water uptake, even when seeds are unavoidable exposed to a moist environment. In this work, the effect of hydrophobic dressings was tested on the germination rate of sugar beet (Beta vulgaris L.) and broccolis (Brassica oleraceae var italic L.) seeds under laboratorial condition. Zein, natural maize (Zea mays L.) proteins extracted from gluten meal, was used as precursor polymers to form the coatings. Seeds were dressed by direct submersion into a zein/ethanol formulation of zein concentration of 3.0 g L-1, followed by natural air drying. The resultant coating has elevated the hydrophobic feature due to the high content amino acids present in the structure of the zein. For both types of seeds an overall delay in sprouting and germination was observed, with a more accentuated reduction on sugar beet germination percentage after eleven days of measurements. The effect on germination rates is understood as the efficiency of the zein coating to form a physical barrier preventing water permeation into the seeds.Filmes com características hidrofóbicas baseados em proteínas foram avaliados como revestimento em sementes de beterraba e brócolis, com o objetivo de prevenir germinações prematuras pela redução na absorção de água. Zeínas, proteínas naturais extraídas do glúten de milho, foram empregados como polímeros precursores na elaboração das soluções de cobertura. Os revestimentos se deram pela completa imersão das sementes em formulação zeínas/etanol na concentração de 3,0 g L-1, seguidos de secagem ao ar. Os filmes resultantes apresentam elevada natureza hidrofóbica como resultado do alto teor de amino ácidos presentes na estrutura dessas proteínas. Para ambas as sementes testadas, os resultados apontam um atraso no período de geminação, sendo mais acentuado na porcentagem medida para a beterraba após o período de 11 dias. As diferenças entre as taxas de germinação são discutidas em termos da ação do filme como barreira física reduzindo a permeação de água para o interior das sementes. O estudo demonstra potencial aplicação de zeínas como substrato na redução de germinações indesejáveis durante estocagem em substituição a polímeros usualmente empregados para este fim