The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Huh Chyun Wey - One of the best experts on this subject based on the ideXlab platform.
-
Dissolution-enzyme kinetics of 11β-hydroxylation of cortexolone by Curvularia lunata
Enzyme and Microbial Technology, 1990Co-Authors: Kuo Cheng Chen, Huh Chyun WeyAbstract:The enzyme kinetics of 11β-hydroxylation of cortexolone by whole cells of Curvularia lunata were studied, taking into account the dissolution of the solid substrate. The dissolution behavior of substrate steroid was represented by an empirical expression. A mathematical model was developed to describe the heterogeneous process of steroid hydroxylation, based on the rate of enzyme reaction and the rate of substrate dissolution. The rate of 11β-hydroxylation of solubilized cortexolone coexisting with its solid form was found to be identical to Michaelis-Menten kinetics. The kinetic constants were estimated using experimental data. The good agreement between correlated and experimental values supported the suitability of the established model. © 1990.
Jie Chen - One of the best experts on this subject based on the ideXlab platform.
-
involvement of a velvet protein clvelb in the regulation of vegetative differentiation oxidative stress response secondary metabolism and virulence in Curvularia lunata
Scientific Reports, 2017Co-Authors: Chuanjin Yu, Meng Wang, Yaqian Li, Jie ChenAbstract:Involvement of a velvet protein ClVelB in the regulation of vegetative differentiation, oxidative stress response, secondary metabolism, and virulence in Curvularia lunata
-
efficient agrobacterium tumefaciens mediated target gene disruption in the maize pathogen Curvularia lunata
European Journal of Plant Pathology, 2016Co-Authors: Li Zhang, Hui Li, Shuqin Xiao, Yuanyuan Lu, G F Li, Jie ChenAbstract:Curvularia lunata causes Curvularia leaf spot disease of maize, resulting in periodically significant yield losses around the world. To understand the molecular mechanisms of fungal pathogenicity and virulence factors contributed to the host, here we report a knockout transformation system against target genes. The concentration of conidia, Agrobacterium cell density, and method of co-incubation were optimized for deletion of the gene encoding 1, 3, 8-trihydroxynaphthalene reductase (Brn1), a gene in the melanin biosynthesis pathway, as a test case. Transformants contained a single T-DNA copy. The Brn1 mutant strain was reduced in virulence compared with the wild type strain when inoculated on susceptible maize. Transformation efficiency was 130 ± 10 transformants per 1 × 105 germlings and homologous recombination efficiency was 60.0 to 100.0 %.
-
expression of green fluorescent protein in Curvularia lunata causing maize leaf spot
Canadian Journal of Plant Pathology-revue Canadienne De Phytopathologie, 2010Co-Authors: Guangji Li, Jie ChenAbstract:Curvularia lunata is a widespread fungal pathogen infecting maize leaves. In this study, we developed a genetic transformation system for C. lunata by using the plasmid (pCPXHY1Egfp) with both enhanced green fluorescent protein gene egfp and hygromycin resistance gene hph. GFP rendered hyphae of the transformants fluorescent in culture. Most transformants that showed constitutively expressing EGFP were comparable to the wild-type strain in morphological features. PCR and Southern blot analyses of the hph gene further confirmed that the plasmid was integrated into the genome of C. lunata. This is the first report that a ‘reporter’ gene, egfp, could be stably expressed in C. lunata. Using the transformants with EGFP marker will assist us to visualize the features of infection at different stages.
José María Arias - One of the best experts on this subject based on the ideXlab platform.
-
BIOTRANSFORMATION OF ENT-BEYERENONES BY RHIZOPUS NIGRICANS AND Curvularia lunata CULTURES
Phytochemistry, 1994Co-Authors: Andrés García-granados, Antonio José Moreno Guerrero, Antonio Martínez, Andrés Parra, José María AriasAbstract:Abstract We have demonstrated the biotransformation of ent -7α,18-diacetoxybeyer-15-en-14-one, ent -14β,18-diacetoxybeyer-15-en-7-one and ent - 1β-acetoxy-17-hydroxybeyer-15-en-12-one by Rhizopus nigricans and Curvularia lunata cultures. Rhizopus nigricans metabolized the indicated substrates at higher yields than C. lunata to give hydroxylations at C-3, C-1 and C-12, if the substrates were functionalized at C-7, C- 14 and C-18. However, when the substrates were functionalized at C-1, C-12 and C-17, R. nigricans hydroxylated at C-19 and C. lunata at C-18.
-
chemical microbiological synthesis of 6β eudesmanolides by Curvularia lunata cultures from eudesmanes with functions at c 1 and c 6
Tetrahedron, 1991Co-Authors: Andres Garciagranados, Francisco Rivas, Antonio Martínez, Ma Esther Onorato, José María AriasAbstract:Abstract The biotransformation of several 1,6-difunctionalized eudesmanes was carried out with Curvularia lunata cultures in order to obtain 11-R and 11-S 12-hydroxy derivatives, which were oxidized with RuH2(Ph3P)4 to give 11-R and 11-S-6seudesmanolides. The best results were achieved by biotransformatlon of the 1,6-diketo compound, which allowed us to obtain a considerable yield of 11-R-eudesmanolides.
U. C. Banerjee - One of the best experts on this subject based on the ideXlab platform.
-
optimization of culture conditions for the production of rifamycin oxidase by Curvularia lunata
World Journal of Microbiology & Biotechnology, 1994Co-Authors: U. C. BanerjeeAbstract:Maximum activity (8.9 IU/ml) of rifamycin oxidase in Curvularia lunata, grown in shake-flask culture at 28°C and pH 6.5, was after 96 h. Nearly all the glucose was used in 72 h. An initial culture pH of 6.5 and 28°C were optimum for the growth and enzyme production. Among various carbon and organic nitrogen sources, carboxymethylcellulose and peptone were the most effective for enzyme yield. The rate of enzyme production was enhanced when yeast extract was also added to the medium. The optimum medium for the production of rifamycin oxidase contained 10 g each of yeast extract, peptone and carboxymethylcellulose/l and 0.04% (NH4)2SO4.
-
Growth and production of rifamycin oxidase by Curvularia lunata
Folia Microbiologica, 1994Co-Authors: U. C. BanerjeeAbstract:Curvularia lunata could neither grow nor produce rifamycin oxidase in synthetic media without peptone and yeast extract. Mycelia grown on complex media were tested for the ability to produce rifamycin oxidase in synthetic media. The optimum concentrations of peptone and yeast extract were in the range of 7.5–10 g/L. Five percent inoculum size was found to be optimum for good growth and enzyme production. Addition of metal ions to the cultivation medium increased the enzyme activity.
-
Transformation of rifamycin B with immobilized rifamycin oxidase of Curvularia lunata
Biotechnology Techniques, 1993Co-Authors: U. C. BanerjeeAbstract:Rifamycin oxidase of Curvularia lunata was immobilized on polyacrylamide gel. The optimum pH and temperature for immobilized enzyme reaction were 6.5 and 50 °C, respectively. Enzyme stability increased on immobilization and the half lives of immobilized enzyme preparations at 30 and 40 °C were 30 and 11.5 d, respectively. With 2.5 mm beads diffusional resistances were observed. Reusability studies showed that 1 mm size beads gave a higher rate of transformation in comparison with 2 or 2.5 mm beads.
Kuo Cheng Chen - One of the best experts on this subject based on the ideXlab platform.
-
11β-Hydroxylation of coxtexolone by Curvularia lunata
Enzyme and Microbial Technology, 1990Co-Authors: Kuo Cheng ChenAbstract:Abstract The 11β-hydroxylase of Curvularia lunata (NRRL 2380) was demonstrated to be nonconstitutive and intracellularly inducible by cortexolone. The pH change and the color development associated with the mycelial growth can serve as convenient criteria for 11β-hydroxylation process. The feeding time of steroid substrate affects the hydroxylation rate significantly. Feeding of substrate was found to be best at around 8 h of incubation. Hydroxylation could be enhanced when induction was performed at low dissolved oxygen tension (DOT), followed later by DOT elevation in the culture. The effect of DOT on enzyme expression was investigated showing an optimum DOT value of 5.5 ppm for maximum hydroxylation rate .
-
Dissolution-enzyme kinetics of 11β-hydroxylation of cortexolone by Curvularia lunata
Enzyme and Microbial Technology, 1990Co-Authors: Kuo Cheng Chen, Huh Chyun WeyAbstract:The enzyme kinetics of 11β-hydroxylation of cortexolone by whole cells of Curvularia lunata were studied, taking into account the dissolution of the solid substrate. The dissolution behavior of substrate steroid was represented by an empirical expression. A mathematical model was developed to describe the heterogeneous process of steroid hydroxylation, based on the rate of enzyme reaction and the rate of substrate dissolution. The rate of 11β-hydroxylation of solubilized cortexolone coexisting with its solid form was found to be identical to Michaelis-Menten kinetics. The kinetic constants were estimated using experimental data. The good agreement between correlated and experimental values supported the suitability of the established model. © 1990.
