The Experts below are selected from a list of 1623 Experts worldwide ranked by ideXlab platform
Peter Boger - One of the best experts on this subject based on the ideXlab platform.
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quantitative structure activity relationship of fluridone derivatives with phytoene desaturase
Pesticide Biochemistry and Physiology, 1992Co-Authors: Gerhard Sandmann, Susanne Kowalczykschroder, Harold M Taylor, Peter BogerAbstract:Abstract Structure-activity investigations were carried out with fluridone analogs which are inhibitors of the enzyme phytoene desaturase. The chemical modifications of the 21 bleaching compounds used were all positioned at the pyridinone ring. Inhibition of carotenoid biosynthesis was determined either with intact cells of the cyanobacterium Aphanocapsa or with isolated Aphanocapsa thylakoid membranes assaying inhibition of phytoene desaturation. Methyl was found to be a favorable N -substituent, and the aromatic nature of the heterocycle is not essential although the resulting piperidinone showed lower bleaching activity. Replacement of the keto group by either methoxy or dimethylamine resulted in lowered but still substantial inhibition. The corresponding thione or chloro derivatives were more or less inactive. Quantitative structure-activity correlations were calculated between inhibitory activity and physicochemical properties of the substituents at position 3 of the pyridinone ring. Regression analysis showed a significant correlation between cellular I 50 values and lipophilicity π and σ p . Using in vitro data the contribution of σ p to the regression was not significant.
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Quantitative structure—Activity relationship of fluridone derivatives with phytoene desaturase
Pesticide Biochemistry and Physiology, 1992Co-Authors: Gerhard Sandmann, Harold M Taylor, Susanne Kowalczyk-schröder, Peter BogerAbstract:Abstract Structure-activity investigations were carried out with fluridone analogs which are inhibitors of the enzyme phytoene desaturase. The chemical modifications of the 21 bleaching compounds used were all positioned at the pyridinone ring. Inhibition of carotenoid biosynthesis was determined either with intact cells of the cyanobacterium Aphanocapsa or with isolated Aphanocapsa thylakoid membranes assaying inhibition of phytoene desaturation. Methyl was found to be a favorable N -substituent, and the aromatic nature of the heterocycle is not essential although the resulting piperidinone showed lower bleaching activity. Replacement of the keto group by either methoxy or dimethylamine resulted in lowered but still substantial inhibition. The corresponding thione or chloro derivatives were more or less inactive. Quantitative structure-activity correlations were calculated between inhibitory activity and physicochemical properties of the substituents at position 3 of the pyridinone ring. Regression analysis showed a significant correlation between cellular I 50 values and lipophilicity π and σ p . Using in vitro data the contribution of σ p to the regression was not significant.
Gerhard Sandmann - One of the best experts on this subject based on the ideXlab platform.
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interference of fluridone with the desaturation of phytoene by membranes of the cyanobacterium Aphanocapsa
Pesticide Biochemistry and Physiology, 1992Co-Authors: Susanne Kowalczykschroder, Gerhard SandmannAbstract:Abstract The effect of the bleaching herbicide fluridone was investigated by in vivo and in vitro studies using the cyanobacterium Aphanocapsa. After application, all colored carotenoids and chlorophyll decreased, and phytoene was accumulated in the cells. Direct inhibition of phytoene desaturation was demonstrated with a membrane preparation that converts geranylgeranyl pyrophosphate into phytoene and further to β-carotene. A double-reciprocal plot of phytoene conversion into β-carotene in the presence of fluridone and binding studies with radioactive labeled fluridone showed that this herbicide is a reversible noncompetitive inhibitor of phytoene desaturase.
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quantitative structure activity relationship of fluridone derivatives with phytoene desaturase
Pesticide Biochemistry and Physiology, 1992Co-Authors: Gerhard Sandmann, Susanne Kowalczykschroder, Harold M Taylor, Peter BogerAbstract:Abstract Structure-activity investigations were carried out with fluridone analogs which are inhibitors of the enzyme phytoene desaturase. The chemical modifications of the 21 bleaching compounds used were all positioned at the pyridinone ring. Inhibition of carotenoid biosynthesis was determined either with intact cells of the cyanobacterium Aphanocapsa or with isolated Aphanocapsa thylakoid membranes assaying inhibition of phytoene desaturation. Methyl was found to be a favorable N -substituent, and the aromatic nature of the heterocycle is not essential although the resulting piperidinone showed lower bleaching activity. Replacement of the keto group by either methoxy or dimethylamine resulted in lowered but still substantial inhibition. The corresponding thione or chloro derivatives were more or less inactive. Quantitative structure-activity correlations were calculated between inhibitory activity and physicochemical properties of the substituents at position 3 of the pyridinone ring. Regression analysis showed a significant correlation between cellular I 50 values and lipophilicity π and σ p . Using in vitro data the contribution of σ p to the regression was not significant.
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Quantitative structure—Activity relationship of fluridone derivatives with phytoene desaturase
Pesticide Biochemistry and Physiology, 1992Co-Authors: Gerhard Sandmann, Harold M Taylor, Susanne Kowalczyk-schröder, Peter BogerAbstract:Abstract Structure-activity investigations were carried out with fluridone analogs which are inhibitors of the enzyme phytoene desaturase. The chemical modifications of the 21 bleaching compounds used were all positioned at the pyridinone ring. Inhibition of carotenoid biosynthesis was determined either with intact cells of the cyanobacterium Aphanocapsa or with isolated Aphanocapsa thylakoid membranes assaying inhibition of phytoene desaturation. Methyl was found to be a favorable N -substituent, and the aromatic nature of the heterocycle is not essential although the resulting piperidinone showed lower bleaching activity. Replacement of the keto group by either methoxy or dimethylamine resulted in lowered but still substantial inhibition. The corresponding thione or chloro derivatives were more or less inactive. Quantitative structure-activity correlations were calculated between inhibitory activity and physicochemical properties of the substituents at position 3 of the pyridinone ring. Regression analysis showed a significant correlation between cellular I 50 values and lipophilicity π and σ p . Using in vitro data the contribution of σ p to the regression was not significant.
Harold M Taylor - One of the best experts on this subject based on the ideXlab platform.
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quantitative structure activity relationship of fluridone derivatives with phytoene desaturase
Pesticide Biochemistry and Physiology, 1992Co-Authors: Gerhard Sandmann, Susanne Kowalczykschroder, Harold M Taylor, Peter BogerAbstract:Abstract Structure-activity investigations were carried out with fluridone analogs which are inhibitors of the enzyme phytoene desaturase. The chemical modifications of the 21 bleaching compounds used were all positioned at the pyridinone ring. Inhibition of carotenoid biosynthesis was determined either with intact cells of the cyanobacterium Aphanocapsa or with isolated Aphanocapsa thylakoid membranes assaying inhibition of phytoene desaturation. Methyl was found to be a favorable N -substituent, and the aromatic nature of the heterocycle is not essential although the resulting piperidinone showed lower bleaching activity. Replacement of the keto group by either methoxy or dimethylamine resulted in lowered but still substantial inhibition. The corresponding thione or chloro derivatives were more or less inactive. Quantitative structure-activity correlations were calculated between inhibitory activity and physicochemical properties of the substituents at position 3 of the pyridinone ring. Regression analysis showed a significant correlation between cellular I 50 values and lipophilicity π and σ p . Using in vitro data the contribution of σ p to the regression was not significant.
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Quantitative structure—Activity relationship of fluridone derivatives with phytoene desaturase
Pesticide Biochemistry and Physiology, 1992Co-Authors: Gerhard Sandmann, Harold M Taylor, Susanne Kowalczyk-schröder, Peter BogerAbstract:Abstract Structure-activity investigations were carried out with fluridone analogs which are inhibitors of the enzyme phytoene desaturase. The chemical modifications of the 21 bleaching compounds used were all positioned at the pyridinone ring. Inhibition of carotenoid biosynthesis was determined either with intact cells of the cyanobacterium Aphanocapsa or with isolated Aphanocapsa thylakoid membranes assaying inhibition of phytoene desaturation. Methyl was found to be a favorable N -substituent, and the aromatic nature of the heterocycle is not essential although the resulting piperidinone showed lower bleaching activity. Replacement of the keto group by either methoxy or dimethylamine resulted in lowered but still substantial inhibition. The corresponding thione or chloro derivatives were more or less inactive. Quantitative structure-activity correlations were calculated between inhibitory activity and physicochemical properties of the substituents at position 3 of the pyridinone ring. Regression analysis showed a significant correlation between cellular I 50 values and lipophilicity π and σ p . Using in vitro data the contribution of σ p to the regression was not significant.
Susanne Kowalczykschroder - One of the best experts on this subject based on the ideXlab platform.
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interference of fluridone with the desaturation of phytoene by membranes of the cyanobacterium Aphanocapsa
Pesticide Biochemistry and Physiology, 1992Co-Authors: Susanne Kowalczykschroder, Gerhard SandmannAbstract:Abstract The effect of the bleaching herbicide fluridone was investigated by in vivo and in vitro studies using the cyanobacterium Aphanocapsa. After application, all colored carotenoids and chlorophyll decreased, and phytoene was accumulated in the cells. Direct inhibition of phytoene desaturation was demonstrated with a membrane preparation that converts geranylgeranyl pyrophosphate into phytoene and further to β-carotene. A double-reciprocal plot of phytoene conversion into β-carotene in the presence of fluridone and binding studies with radioactive labeled fluridone showed that this herbicide is a reversible noncompetitive inhibitor of phytoene desaturase.
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quantitative structure activity relationship of fluridone derivatives with phytoene desaturase
Pesticide Biochemistry and Physiology, 1992Co-Authors: Gerhard Sandmann, Susanne Kowalczykschroder, Harold M Taylor, Peter BogerAbstract:Abstract Structure-activity investigations were carried out with fluridone analogs which are inhibitors of the enzyme phytoene desaturase. The chemical modifications of the 21 bleaching compounds used were all positioned at the pyridinone ring. Inhibition of carotenoid biosynthesis was determined either with intact cells of the cyanobacterium Aphanocapsa or with isolated Aphanocapsa thylakoid membranes assaying inhibition of phytoene desaturation. Methyl was found to be a favorable N -substituent, and the aromatic nature of the heterocycle is not essential although the resulting piperidinone showed lower bleaching activity. Replacement of the keto group by either methoxy or dimethylamine resulted in lowered but still substantial inhibition. The corresponding thione or chloro derivatives were more or less inactive. Quantitative structure-activity correlations were calculated between inhibitory activity and physicochemical properties of the substituents at position 3 of the pyridinone ring. Regression analysis showed a significant correlation between cellular I 50 values and lipophilicity π and σ p . Using in vitro data the contribution of σ p to the regression was not significant.
Marin Mirna - One of the best experts on this subject based on the ideXlab platform.
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Variación espacial y temporal de la diversidad y abundancia de cianobacterias del Lago de Yojoa (2014-2015)
'Latin America Journals Online', 2018Co-Authors: Hernandez Oviedo, Alba Isbela, Marin MirnaAbstract:The objective of the study was to identify and analyze the temporal and spatial variations of the diversity and abundance of cyanobacteria in Lake Yojoa between May 2014 and March 2015. 184 samples were analyzed identifying 9 families and 48 species of cyanobacteria, dominating Microcystis aeruginosa, Aphanocapsa delicatissima and Oscillatoria limosa.The average cell / ml of cyanobacteria per sample decreased progressively, the highest 58,274 in sampling1 and the lowest in sampling 1,665. It is possible that the algal bloom occurred before days 1, since a greenish-brown surface scum corresponding to Oscillatoria limosa and Lyngbya sp. in the process of decomposition, many phytoflagellates and vorticelles between the colonies of Microcystis; Coinciding with high nitrogen and orthophosphate values of that sample.Spatial and temporal diversity were similar. The temporal dominance was greater than the spatial dominance: Microcystis aeruginosa, Chrococcus limneticus, Chrococcus sp, Aphanocapsa delicatissima, Aphanocapsa mucicola, Aphanocapsa elachista, Lyngbya sp, Gleocapsa sp and Pseudoanabaena mucicola were the dominant species. A monitoring plan and management of toxic cyanobacteria blooms is recommended.El objetivo del estudio fue identificar y analizar las variaciones temporales y espaciales de la diversidad y abundancia de las cianobacterias en el lago de Yojoa entre mayo 2014 y marzo 2015. Se analizaron 184 muestras identificandose 9 familias y 48 especies de cianobacterias, dominando Microcystis aeruginosa, Aphanocapsa delicatissima y Oscillatoria limosa. El promedio de cel/ml de cianobacterias por muestreo disminuyeron progresivamente, el mayor 58,274 en muestreo1 y el menor 1,665 en muestreo 6. Es posible que la floración algal haya ocurrido días antes del muestreo 1, ya que se observó una nata superficial color café verdoso correspondiente a Oscillatoria limosa y Lyngbya sp. en proceso de descomposición, muchos fitoflagelados y vorticelas entre las colonias de Microcystis; coincidiendo con valores altos de nitrógeno y ortofosfato de ese muestreo.La diversidad espacial y temporal fueron similares. La dominancia temporal fue mayor que la espacial, dominando: Microcystis aeruginosa, Chrococcus limneticus, Chrococcus sp, Aphanocapsa delicatissima, Aphanocapsa mucicola, Aphanocapsa elachista, Lyngbya sp, Gleocapsa sp y Pseudoanabaena mucicola. Se recomienda un plan de monitoreo y manejo de floraciones de cianobacterias tóxicas
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Variación espacial y temporal de la diversidad y abundancia del fitoplancton del lago de Yojoa en un año hidrológico 2014-2015
'Latin America Journals Online', 2017Co-Authors: Hernandez Oviedo, Alba Isbela, Marin Mirna, Henriquez Lourdes, Garay MarcelaAbstract:The phytoplankton of Lake Yojoa was represented by 81 species: 59% Cyanophyceae, 22% Chlorophyceae, 9% Bacillariophyceae, 4% Zignematophyceae, 3% Euglenophyceae, 2% Trebouxiophyceae and 1% Dinophyceae.The beta phytoplankton diversity of Lake Yojoa is relatively high regardless of sampling site and time. The highest specific wealth corresponded to the station in front of the Brisas del Lago Hotel and the lowest to index point. Temporally, the greatest specific richness was in July 2014 and the lowest in January 2015, dominating: Microcystis aeruginosa, Aphanocapsa delicatissima, Aphanocapsa elachista, Oscillatoria limosa, Staurastrum leptocladum, Pseudoanabaena mucícola and Sphaerocystis schroeteri. Spatially, the highest index of dominance corresponded to Quebrada Cianuro and the lowest to Index Point. Temporally, the highest index of dominance was in July 2014 and the lowest in September and November 2014. Spatially, the greatest similarity was found between Puntilla and Cacao and Point Index, and the lowest between the mouth of the Varsovia River and the Quebrada Cianuro mouth. Temporally, the greatest similarity was during and at the end of the dry season 2015, and the lowest between July 2014 and the dry season 2015.The average abundance was higher in May 2014 with 58,616 (Cel / ml), coinciding with the end of an algal bloom event, however, declined progressively during the study. During the first sampling, a greenish-brown superficial cream corresponding to filamentous algae (Oscillatoria limosa and Lyngbya) was observed in decomposition. The marked seasonality of phytoplankton and environmental conditions are the determinants of differences in diversity and abundance found in Lake Yojoa.Revista Ciencia y Tecnología No.19, diciembre 2016, p.40-77El fitoplancton del lago de Yojoa estuvo representado por 81 especies: 59% Cyanophyceae, 22% Chlorophyceae, 9% Bacillariophyceae, 4% Zignematophyceae, 3% Euglenophyceae, 2% Trebouxiophyceae y 1% Dinophyceae.La diversidad beta del fitoplancton del lago de Yojoa es relativamente alta independientemente del lugar y época de muestreo. La mayor riqueza específica correspondió a la estación frente al Hotel Brisas del Lago y la menor a Punto índice. Temporalmente, la mayor riqueza específica fue en Julio de 2014 y la menor en Enero de 2015, dominando: Microcystis aeruginosa, Aphanocapsa delicatissima, Aphanocapsa elachista, Oscillatoria limosa, Staurastrum leptocladum, Pseudoanabaena mucícola y Sphaerocystis schroeteri. Espacialmente, el mayor índice de dominancia correspondió a Quebrada Cianuro y el menor al Punto Índice. Temporalmente, el mayor índice de dominancia fue en Julio 2014 y el menor en época lluviosa y al final de la misma época. Espacialmente, la mayor similitud se encontró entre Puntilla y el Cacao y Punto Índice, y la menor entre la desembocadura del Río Varsovia y desembocadura Quebrada Cianuro. Temporalmente, la mayor similitud fue durante y a finales de época seca 2015, y la menor entre Julio 2014 y época seca 2015.El promedio de la abundancia fue mayor en Mayo 2014 con 58,616 (Cel/ml), coincidiendo con el final de un evento de floración algal, sin embargo, disminuyó progresivamente durante el estudio. Al realizar el primer muestreo se observó una nata superficial color café verdoso correspondiente a algas filamentosas (Oscillatoria limosa y Lyngbya) en descomposición. La marcada estacionalidad del fitoplancton y las condiciones ambientales son los factores determinantes de las diferencias en la diversidad y abundancia encontrada en el lago de Yojoa.Revista Ciencia y Tecnología No.19, diciembre 2016, p.40-2