The Experts below are selected from a list of 57 Experts worldwide ranked by ideXlab platform
Adnan Uzunovic - One of the best experts on this subject based on the ideXlab platform.
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inhibition of basidiospore germination by western redcedar heartwood extractives
International Biodeterioration & Biodegradation, 2016Co-Authors: Rod Stirling, Adnan UzunovicAbstract:Abstract Understanding the relationship between extractives and decay resistance in western red cedar (WRC) is essential for breeding durable planting stock. To date, most such work has focused on resistance to mycelial attack. However, this is potentially misleading since WRC is largely used in above-ground applications where basidiospore germination is the primary way in which the wood is initially colonized. Efficacy against basidiospores is likely a critical factor affecting wood’s decay resistance in above-ground applications. In this study the effect of selected extractives on basidiospore germination was evaluated. Partially-extracted WRC veneer samples, and spruce samples treated with beta-thujaplicin, thujic Acid, or Plicatic Acid were used. Beta-thujaplicin and thujic Acid were associated with significantly reduced rates of Gloeophyllum sepiarium , Fomitopsis palustris, and Dichomitus squalens basidiospore germination. Plicatic Acid was not associated with any effect on basidiospore germination. Planting stock that generates heartwood with high concentrations of thujaplicins and thujic Acid should be selected to yield wood that will be resistant to basidiospore germination.
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inhibition of basidiospore germination by western redcedar heartwood extractives
International Biodeterioration & Biodegradation, 2016Co-Authors: Rod Stirling, Adnan UzunovicAbstract:Abstract Understanding the relationship between extractives and decay resistance in western red cedar (WRC) is essential for breeding durable planting stock. To date, most such work has focused on resistance to mycelial attack. However, this is potentially misleading since WRC is largely used in above-ground applications where basidiospore germination is the primary way in which the wood is initially colonized. Efficacy against basidiospores is likely a critical factor affecting wood’s decay resistance in above-ground applications. In this study the effect of selected extractives on basidiospore germination was evaluated. Partially-extracted WRC veneer samples, and spruce samples treated with beta-thujaplicin, thujic Acid, or Plicatic Acid were used. Beta-thujaplicin and thujic Acid were associated with significantly reduced rates of Gloeophyllum sepiarium , Fomitopsis palustris, and Dichomitus squalens basidiospore germination. Plicatic Acid was not associated with any effect on basidiospore germination. Planting stock that generates heartwood with high concentrations of thujaplicins and thujic Acid should be selected to yield wood that will be resistant to basidiospore germination.
Norman G Lewis - One of the best experts on this subject based on the ideXlab platform.
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crystal structures of apo form and binary ternary complexes of podophyllum secoisolariciresinol dehydrogenase an enzyme involved in formation of health protecting and plant defense lignans
Journal of Biological Chemistry, 2005Co-Authors: Buhyun Youn, Syed G A Moinuddin, Laurence B Davin, Norman G Lewis, Chulhee KangAbstract:Abstract (-)-Matairesinol is a central biosynthetic intermediate to numerous 8–8′-lignans, including the antiviral agent podophyllotoxin in Podophyllum species and its semi-synthetic anticancer derivatives teniposide, etoposide, and Etopophos®. It is formed by action of an enantiospecific secoisolariciresinol dehydrogenase, an NAD(H)-dependent oxidoreductase that catalyzes the conversion of (-)-secoisolariciresinol. Matairesinol is also a plant-derived precursor of the cancer-preventative “mammalian” lignan or “phytoestrogen” enterolactone, formed in the gut following ingestion of high fiber dietary foodstuffs, for example. Additionally, secoisolariciresinol dehydrogenase is involved in pathways to important plant defense molecules, such as Plicatic Acid in the western red cedar (Thuja plicata) heartwood. To understand the molecular and enantiospecific basis of Podophyllum secoisolariciresinol dehydrogenase, crystal structures of the apo-form and binary/ternary complexes were determined at 1.6, 2.8, and 2.0 A resolution, respectively. The enzyme is a homotetramer, consisting of an α/β single domain monomer containing seven parallel β-strands flanked by eight α-helices on both sides. Its overall monomeric structure is similar to that of NAD(H)-dependent short-chain dehydrogenases/reductases, with a conserved Asp47 forming a hydrogen bond with both hydroxyl groups of the adenine ribose of NAD(H), and thus specificity toward NAD(H) instead of NADP(H). The highly conserved catalytic triad (Ser153, Tyr167, and Lys171) is adjacent to both NAD+ and substrate molecules, where Tyr167 functions as a general base. Following analysis of high resolution structures of the apo-form and two complex forms, the molecular basis for both the enantio-specificity and the reaction mechanism of secoisolariciresinol dehydrogenase is discussed and compared with that of pinoresinol-lariciresinol reductase.
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the western red cedar thuja plicata 8 8 dirigent family displays diverse expression patterns and conserved monolignol coupling specificity
Plant Molecular Biology, 2002Co-Authors: Myoung K Kim, Laurence B Davin, Jae Heung Jeon, Masayuki Fujita, Norman G LewisAbstract:The isolation and characterization of a multigene family of the first class of dirigent proteins (namely that mainly involved in 8-8′ coupling leading to (+)-pinoresinol in this case) is reported, this comprising of nine western red cedar (Thuja plicata) DIRIGENT genes (DIR1–9) of 72–99.5% identity to each other. Their corresponding cDNA clones had coding regions for 180–183 amino Acids with each having a predicted molecular mass of ca. 20 kDa including the signal peptide. Real time-PCR established that the DIRIGENT isovariants were differentially expressed during growth and development of T. plicata (P<0.05). The phylogenetic relationships and the rates and patterns of nucleotide substitution suggest that the DIRIGENT gene may have evolved via paralogous expansion at an early stage of vascular plant diversification. Thereafter, western red cedar paralogues have maintained an high homogeneity presumably via a concerted evolutionary mode. This, in turn, is assumed to be the driving force for the differential formation of 8-8′-linked pinoresinol derived (poly)lignans in the needles, stems, bark and branches, as well as for massive accumulation of 8-8′-linked Plicatic Acid-derived (poly)lignans in heartwood.
Rod Stirling - One of the best experts on this subject based on the ideXlab platform.
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inhibition of basidiospore germination by western redcedar heartwood extractives
International Biodeterioration & Biodegradation, 2016Co-Authors: Rod Stirling, Adnan UzunovicAbstract:Abstract Understanding the relationship between extractives and decay resistance in western red cedar (WRC) is essential for breeding durable planting stock. To date, most such work has focused on resistance to mycelial attack. However, this is potentially misleading since WRC is largely used in above-ground applications where basidiospore germination is the primary way in which the wood is initially colonized. Efficacy against basidiospores is likely a critical factor affecting wood’s decay resistance in above-ground applications. In this study the effect of selected extractives on basidiospore germination was evaluated. Partially-extracted WRC veneer samples, and spruce samples treated with beta-thujaplicin, thujic Acid, or Plicatic Acid were used. Beta-thujaplicin and thujic Acid were associated with significantly reduced rates of Gloeophyllum sepiarium , Fomitopsis palustris, and Dichomitus squalens basidiospore germination. Plicatic Acid was not associated with any effect on basidiospore germination. Planting stock that generates heartwood with high concentrations of thujaplicins and thujic Acid should be selected to yield wood that will be resistant to basidiospore germination.
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inhibition of basidiospore germination by western redcedar heartwood extractives
International Biodeterioration & Biodegradation, 2016Co-Authors: Rod Stirling, Adnan UzunovicAbstract:Abstract Understanding the relationship between extractives and decay resistance in western red cedar (WRC) is essential for breeding durable planting stock. To date, most such work has focused on resistance to mycelial attack. However, this is potentially misleading since WRC is largely used in above-ground applications where basidiospore germination is the primary way in which the wood is initially colonized. Efficacy against basidiospores is likely a critical factor affecting wood’s decay resistance in above-ground applications. In this study the effect of selected extractives on basidiospore germination was evaluated. Partially-extracted WRC veneer samples, and spruce samples treated with beta-thujaplicin, thujic Acid, or Plicatic Acid were used. Beta-thujaplicin and thujic Acid were associated with significantly reduced rates of Gloeophyllum sepiarium , Fomitopsis palustris, and Dichomitus squalens basidiospore germination. Plicatic Acid was not associated with any effect on basidiospore germination. Planting stock that generates heartwood with high concentrations of thujaplicins and thujic Acid should be selected to yield wood that will be resistant to basidiospore germination.
Moira Chanyeung - One of the best experts on this subject based on the ideXlab platform.
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t lymphocyte responses to Plicatic Acid human serum albumin conjugate in occupational asthma caused by western red cedar
The Journal of Allergy and Clinical Immunology, 1998Co-Authors: Anthony J Frew, Kukuh Noertjojo, Henry Chan, Paul Keown, Santiago Quirce, Jung Hyun Chang, Moira ChanyeungAbstract:BACKGROUND: T cells are known to play a major role in the pathogenesis of atopic allergic asthma, but it is less clear whether they are involved in occupational asthma caused by low molecular weight chemicals such as Plicatic Acid. OBJECTIVES: We sought to determine whether peripheral blood T cells from patients with western red cedar asthma (WRCA) recognize Plicatic Acid (PA) conjugated to human serum albumin (HSA) as judged by proliferation or cytokine production and to analyze the response to PA inhalation with flow cytometry. RESULTS: Significant proliferative responses to PA-HSA were observed in eight of 33 patients with WRCA, none of 10 exposed nonasthmatic cedar workers, and one of 18 nonasthmatic control subjects. Two of 25 patients with WRCA also showed proliferative responses to unconjugated PA. All the WRCA responders were either currently exposed to cedar or had ceased exposure within the preceding 2 years. None of the four patients receiving oral steroids responded, but inhaled steroids did not seem to influence responsiveness. No correlations were found between the maximum stimulation response and any of the current FEV1 values, the current PC20 methacholine values, or the magnitude of the late asthmatic response to PA. Peripheral blood T-cell subset proportions and their degree of activation were similar in patients with WRCA and exposed control subjects. There was no change in T-cell phenotypes or their activation markers after PA inhalation challenge. In vitro, PA-HSA stimulation did not affect subset ratios but led to release of small amounts of IL-5 and IFN-gamma, with no detectable increase in IL-4. CONCLUSIONS: PA-HSA-specific T lymphocytes seem to be present in small numbers in the peripheral blood of patients with WRCA and may respond to antigenic exposure by producing IFN-gamma and IL-5. However, the proportion of responding cells would appear to be lower than in comparable studies of atopic asthma.
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bronchial hyperresponsiveness and level of exposure in occupational asthma due to western red cedar thuja plicata serial observations before and after development of symptoms
The American review of respiratory disease, 1992Co-Authors: Moira Chanyeung, Alain DesjardinsAbstract:Four workers from a cedar sawmill who developed red cedar asthma are described. They had serial measurements of lung function and nonspecific bronchial hyperresponsiveness (NSBH) several years before and after the development of chest symptoms. Measurements of dust concentration and specific IgE antibodies to Plicatic Acid-human serum albumin (PA-HSA) conjugate were also carried out before the onset of disease. NSBH developed in parallel with the development of asthma and was not present in any of the workers beforehand, indicating that it is not a predisposing host factor. Nasal symptoms preceded chest symptoms in three workers, suggesting that this may be an early marker of the disease. Although dust concentrations for jobs located both inside and outside the sawmill were low, jobs associated with somewhat higher exposures were associated with the initiation of asthma symptoms.
Laurence B Davin - One of the best experts on this subject based on the ideXlab platform.
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crystal structures of apo form and binary ternary complexes of podophyllum secoisolariciresinol dehydrogenase an enzyme involved in formation of health protecting and plant defense lignans
Journal of Biological Chemistry, 2005Co-Authors: Buhyun Youn, Syed G A Moinuddin, Laurence B Davin, Norman G Lewis, Chulhee KangAbstract:Abstract (-)-Matairesinol is a central biosynthetic intermediate to numerous 8–8′-lignans, including the antiviral agent podophyllotoxin in Podophyllum species and its semi-synthetic anticancer derivatives teniposide, etoposide, and Etopophos®. It is formed by action of an enantiospecific secoisolariciresinol dehydrogenase, an NAD(H)-dependent oxidoreductase that catalyzes the conversion of (-)-secoisolariciresinol. Matairesinol is also a plant-derived precursor of the cancer-preventative “mammalian” lignan or “phytoestrogen” enterolactone, formed in the gut following ingestion of high fiber dietary foodstuffs, for example. Additionally, secoisolariciresinol dehydrogenase is involved in pathways to important plant defense molecules, such as Plicatic Acid in the western red cedar (Thuja plicata) heartwood. To understand the molecular and enantiospecific basis of Podophyllum secoisolariciresinol dehydrogenase, crystal structures of the apo-form and binary/ternary complexes were determined at 1.6, 2.8, and 2.0 A resolution, respectively. The enzyme is a homotetramer, consisting of an α/β single domain monomer containing seven parallel β-strands flanked by eight α-helices on both sides. Its overall monomeric structure is similar to that of NAD(H)-dependent short-chain dehydrogenases/reductases, with a conserved Asp47 forming a hydrogen bond with both hydroxyl groups of the adenine ribose of NAD(H), and thus specificity toward NAD(H) instead of NADP(H). The highly conserved catalytic triad (Ser153, Tyr167, and Lys171) is adjacent to both NAD+ and substrate molecules, where Tyr167 functions as a general base. Following analysis of high resolution structures of the apo-form and two complex forms, the molecular basis for both the enantio-specificity and the reaction mechanism of secoisolariciresinol dehydrogenase is discussed and compared with that of pinoresinol-lariciresinol reductase.
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the western red cedar thuja plicata 8 8 dirigent family displays diverse expression patterns and conserved monolignol coupling specificity
Plant Molecular Biology, 2002Co-Authors: Myoung K Kim, Laurence B Davin, Jae Heung Jeon, Masayuki Fujita, Norman G LewisAbstract:The isolation and characterization of a multigene family of the first class of dirigent proteins (namely that mainly involved in 8-8′ coupling leading to (+)-pinoresinol in this case) is reported, this comprising of nine western red cedar (Thuja plicata) DIRIGENT genes (DIR1–9) of 72–99.5% identity to each other. Their corresponding cDNA clones had coding regions for 180–183 amino Acids with each having a predicted molecular mass of ca. 20 kDa including the signal peptide. Real time-PCR established that the DIRIGENT isovariants were differentially expressed during growth and development of T. plicata (P<0.05). The phylogenetic relationships and the rates and patterns of nucleotide substitution suggest that the DIRIGENT gene may have evolved via paralogous expansion at an early stage of vascular plant diversification. Thereafter, western red cedar paralogues have maintained an high homogeneity presumably via a concerted evolutionary mode. This, in turn, is assumed to be the driving force for the differential formation of 8-8′-linked pinoresinol derived (poly)lignans in the needles, stems, bark and branches, as well as for massive accumulation of 8-8′-linked Plicatic Acid-derived (poly)lignans in heartwood.