6 results on '"Erna Xun"'
Search Results
2. Immobilization of Laccase for Oxidative Coupling of Trans-Resveratrol and Its Derivatives
- Author
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Tiexin Cheng, Zhi Wang, Tengfei Ji, Lei Wang, Ge Chen, Hong Zhang, Jiaxin Wang, and Erna Xun
- Subjects
laccase ,SBA-15 ,immobilization ,oxidative coupling ,resveratrol ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Trametes villosa Laccase (TVL) was immobilized through physical adsorption on SBA-15 mesoporous silica and the immobilized TVL was used in the oxidative coupling of trans-resveratrol. Higher loading and activity of the immobilized enzyme on SBA-15 were obtained when compared with the free enzyme. The effects of reaction conditions, such as buffer type, pH, temperature and substrate concentration were investigated, and the optimum conditions were screened and resulted in enzyme activity of up to 10.3 μmol/g·h. Furthermore, the oxidative couplings of the derivatives of trans-resveratrol were also catalyzed by immobilized TVL. The immobilized TVL was recyclable and could maintain 78% of its initial activity after reusing it four times.
- Published
- 2012
- Full Text
- View/download PDF
3. Heavy metals in nectar modify behaviors of pollinators and nectar robbers: Consequences for plant fitness
- Author
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Jixun Guo, Erna Xun, Ji-Min Zhao, and Yan-Wen Zhang
- Subjects
0106 biological sciences ,Plant Nectar ,Pollination ,Health, Toxicology and Mutagenesis ,Foraging ,Zoology ,Flowers ,Biology ,Toxicology ,010603 evolutionary biology ,01 natural sciences ,Plant reproduction ,Pollinator ,Metals, Heavy ,Animals ,Soil Pollutants ,Nectar ,Nectar robbing ,Reproductive success ,Reproduction ,General Medicine ,Plants ,Pollution ,Robbing ,Environmental Monitoring ,010606 plant biology & botany - Abstract
Plants growing in heavy-metal-rich soils can accumulate metals into their nectar. Nectar chemical composition can alter foraging behavior of floral visitors (including pollinators and floral antagonists) and further affect plant reproductive fitness. The role of nectar heavy metals in deterring pollinators (e.g., shortening foraging time) has been recently studied, but their effects on plant reproduction via changes in behaviors of both pollinators and floral antagonists (e.g., nectar robbers) are less understood. We experimentally manipulated four nectar heavy metals (Zn, Cu, Ni, and Pb) in a native ornamental plant, Hosta ensata F. Maekawa, to investigate the effect of nectar metals on plant reproductive success. We also recorded nectar robbing as well as foraging time and visitation rate of pollinators to assess whether nectar metals could alter the behavior of antagonists and mutualists. Although metals in nectar had no significant direct effects on plant reproduction via hand-pollination, we detected their positive indirect effects on components of female fitness mediated by pollinators and nectar robbers. Matching effects on female plant fitness, nectar robbers responded negatively to the presence of metals in nectar, robbing metal-treated flowers less often. Pollinators spent less time foraging on metal-treated flowers, but their visitation rate to metal-treated flowers was significantly higher than to control flowers. Moreover, pollinators removed less nectar from flowers treated with metals. Our results provide the first direct evidence to date that heavy metals in nectar are capable of deterring nectar robbers and modifying pollinator foraging behavior to enhance plant reproductive fitness.
- Published
- 2018
4. Translocation of heavy metals from soils into floral organs and rewards of Cucurbita pepo: Implications for plant reproductive fitness
- Author
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Jimin Zhao, Jixun Guo, Yan-Wen Zhang, and Erna Xun
- Subjects
0106 biological sciences ,Plant Nectar ,Health, Toxicology and Mutagenesis ,Stamen ,Flowers ,010501 environmental sciences ,medicine.disease_cause ,01 natural sciences ,Plant reproduction ,Cucurbita pepo ,Cucurbita ,Pollinator ,Pollen ,Metals, Heavy ,Botany ,medicine ,Nectar ,Animals ,Soil Pollutants ,Hyperaccumulator ,Pollination ,0105 earth and related environmental sciences ,biology ,Reproduction ,fungi ,Public Health, Environmental and Occupational Health ,food and beverages ,General Medicine ,Bees ,biology.organism_classification ,Pollution ,Seeds ,010606 plant biology & botany ,Squash - Abstract
Metals and metalloids in soil could be transferred into reproductive organs and floral rewards of hyperaccumulator plants and influence their reproductive success, yet little is known whether non-hyperaccumulator plants can translocate heavy metals from soil into their floral organs and rewards (i.e., nectar and pollen) and, if so, whether plant reproduction will be affected. In our studies, summer squash (Cucurbita pepo L. cv. Golden Apple) was exposed to heavy-metal treatments during bud stage to investigate the translocation of soil-supplemented zinc, copper, nickel and lead into its floral organs (pistil, anther and nectary) and rewards (nectar and pollen) as well as floral metal accumulation effects on its reproduction. The results showed that metals taken up by squash did translocate into its floral organs and rewards, although metal accumulation varied depending on different metal types and concentrations as well as floral organ/reward types. Mean foraging time of honey bees to each male and female flower of squash grown in metal-supplemented soils was shorter relative to that of plants grown in control soils, although the visitation rate of honeybees to both male and female flowers was not affected by metal treatments. Pollen viability, pollen removal and deposition as well as mean mass per seed produced by metal-treated squash that received pollen from plants grown in control soils decreased with elevated soil-supplemented metal concentrations. The fact that squash could translocate soil-supplemented heavy metals into floral organs and rewards indicated possible reproductive consequences caused either directly (i.e., decreasing pollen viability or seed mass) or indirectly (i.e., affecting pollinators' visitation behavior to flowers) to plant fitness.
- Published
- 2017
5. Synthesis of Triptorelin Lactate Catalyzed by Lipase in Organic Media
- Author
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Ge Chen, Hong Zhuang, Ning Tang, Zhi Wang, Lei Wang, Hong Zhang, Jiaxin Wang, Erna Xun, and Hong Yue
- Subjects
Water activity ,Swine ,Kinetics ,triptorelin lactate ,Article ,Catalysis ,Inorganic Chemistry ,lcsh:Chemistry ,Organic chemistry ,Animals ,Physical and Theoretical Chemistry ,Lipase ,Organic Chemicals ,Molecular Biology ,lcsh:QH301-705.5 ,Spectroscopy ,Triptorelin Pamoate ,biology ,Bacteria ,Esterification ,Chemistry ,Organic Chemistry ,Temperature ,Substrate (chemistry) ,Water ,General Medicine ,Hydrogen-Ion Concentration ,Enzyme assay ,Computer Science Applications ,enzyme activity ,lcsh:Biology (General) ,lcsh:QD1-999 ,Yield (chemistry) ,biology.protein ,Lactates ,Solvents ,Triptorelin lactate - Abstract
Triptorelin lactate was successfully synthesized by porcine pancreatic lipase (PPL) in organic solvents. The effects of acyl donor, substrate ratio, organic solvent, temperature, and water activity were investigated. Under the optimum conditions, a yield of 30% for its ester could be achieved in the reaction for about 48 h.
- Published
- 2012
6. Immobilization of Laccase for Oxidative Coupling of Trans-Resveratrol and Its Derivatives.
- Author
-
Hong Zhang, Erna Xun, Jiaxin Wang, Ge Chen, Tiexin Cheng, Zhi Wang, Tengfei Ji, and Lei Wang
- Subjects
- *
OXIDATIVE stress , *RESVERATROL , *DRUG derivatives , *LACCASE , *ENZYME activation , *IMMOBILIZED enzymes - Abstract
Trametes villosa Laccase (TVL) was immobilized through physical adsorption on SBA-15 mesoporous silica and the immobilized TVL was used in the oxidative coupling of trans-resveratrol. Higher loading and activity of the immobilized enzyme on SBA-15 were obtained when compared with the free enzyme. The effects of reaction conditions, such as buffer type, pH, temperature and substrate concentration were investigated, and the optimum conditions were screened and resulted in enzyme activity of up to 10.3 µmol/g·h. Furthermore, the oxidative couplings of the derivatives of trans-resveratrol were also catalyzed by immobilized TVL. The immobilized TVL was recyclable and could maintain 78% of its initial activity after reusing it four times. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
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