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Takashi Asaeda - One of the best experts on this subject based on the ideXlab platform.

Stephan Pflugmacher - One of the best experts on this subject based on the ideXlab platform.

  • β n methylamino l alanine bmaa uptake by the aquatic macrophyte Ceratophyllum demersum
    Ecotoxicology and Environmental Safety, 2011
    Co-Authors: M Esterhuizen, Stephan Pflugmacher, T G Downing
    Abstract:

    Free-living freshwater cyanobacteria contain BMAA in both free cellular and protein-associated forms. Free BMAA released on bloom collapse or during cellular turnover creates a potential source of the non-proteinogenic amino acid for bioaccumulation and biomagnification in aquatic ecosystems. Uptake of free amino acids is well documented in macrophytes and the potential for aquatic macrophytes to bioaccumulate BMAA therefore poses a potential threat where such macrophytes constitute a food source in an ecosystem. BMAA uptake and accumulation by the aquatic macrophyte Ceratophyllum demersum was therefore investigated. Rapid uptake of significant amounts of BMAA was observed in C. demersum. Both free and protein-associated BMAA were observed with protein association following accumulation of free BMAA. The protein association suggests potential biomaccumulation by aquatic macrophytes and offers a possibility of phytoremediation for BMAA removal.

  • phragmites australis and quercus robur leaf extracts affect antioxidative system and photosynthesis of Ceratophyllum demersum
    Ecotoxicology and Environmental Safety, 2007
    Co-Authors: Sheku Kamara, Stephan Pflugmacher
    Abstract:

    During senescence, leaves are deposited on aquatic bodies and decay under water releasing chemical substances that might exert physiological stress to aquatic organisms. Leaf litter alone contributes 30% of the total dissolved organic carbon (DOC) in streams. We investigated the impact of leaves extract from Phragmites australis and Quercus robur on the antioxidative system and photosynthetic rate of the aquatic macrophyte Ceratophyllum demersum exposed for 24 h. Rate of photosynthetic oxygen release and antioxidant enzyme activity (glutathione S-transferases, glutathione reductases and peroxidases) as well as lipid peroxidation in C. demersum were measured. Significant (P<0.01) elevations of antioxidative enzyme activity in C. demersum which tends to plateau at high DOC concentrations were observed. There was no detectable effect on lipid peroxidation. A significant dose-dependent reduction in photosynthetic oxygen production was measured.

  • Phragmites australis and Quercus robur leaf extracts affect antioxidative system and photosynthesis of Ceratophyllum demersum.
    Ecotoxicology and environmental safety, 2006
    Co-Authors: Sheku Kamara, Stephan Pflugmacher
    Abstract:

    During senescence, leaves are deposited on aquatic bodies and decay under water releasing chemical substances that might exert physiological stress to aquatic organisms. Leaf litter alone contributes 30% of the total dissolved organic carbon (DOC) in streams. We investigated the impact of leaves extract from Phragmites australis and Quercus robur on the antioxidative system and photosynthetic rate of the aquatic macrophyte Ceratophyllum demersum exposed for 24 h. Rate of photosynthetic oxygen release and antioxidant enzyme activity (glutathione S-transferases, glutathione reductases and peroxidases) as well as lipid peroxidation in C. demersum were measured. Significant (P

  • effects and metabolism of the phenylurea herbicide isoproturon in the submerged macrophyte Ceratophyllum demersum l
    Journal of applied botany and food quality, 2006
    Co-Authors: Constanze Pietsch, E Krause, B K Burnison, Christian E W Steinberg, Stephan Pflugmacher
    Abstract:

    Phenylurea herbicides such as isoproturon (IPU) restrain photosynthesis by connection to the D1 protein in the photosynthetic apparatus in target plants such as weeds in crop fields. Direct effects of herbicides on organisms, which are not a target of the pesticide, have been examined seldom. Since a many of agriculturally used pesticides are found in surface waters in agricultural areas, we determined the effects on the photosynthetic oxygen production of the submerged macrophyte Ceratophyllum demersum using concentrations of IPU ranging from 0.2 μg/L to 200 μg/L IPU. At environmental relevant concentrations of IPU, the photosynthetic oxygen release was impaired. A reduction of the photosynthetic oxygen release showed a time dependency with the assigned herbicide concentrations. Furthermore, this study presents the first indications for metabolism of IPU in the aquatic plant C. demersum .

Viraj Prasanna Ranawakage - One of the best experts on this subject based on the ideXlab platform.

Hans Brix - One of the best experts on this subject based on the ideXlab platform.

  • Closely related freshwater macrophyte species, Ceratophyllum demersum and C. submersum, differ in temperature response
    Freshwater Biology, 2014
    Co-Authors: Benita Hyldgaard, Brian K. Sorrell, Hans Brix
    Abstract:

    SUMMARY 1. The importance of temperature responses of photosynthesis and respiration in determining species distributions was compared in two closely related freshwater macrophytes, Ceratophyllum demersum and C. submersum. The two species differed significantly in response to temperature in the short and long term, despite being collected in the same geographical region, near Aarhus, Denmark. 2. The distribution of C. submersum is narrower globally and does not extend as far north as C. demersum, which is a cosmopolitan species. Results from short-term (within minutes) temperature-response curves and distributional patterns corresponded well with the long-term (weeks) results obtained, but with some important deviations. The long-term responses of the two species to low temperature (12 °C) were more similar than expected. In contrast, high temperature (35 °C), which stimulated photosynthesis in C. submersum in the short term, inhibited photosynthesis in the long term and resulted in lower growth rates of C. submersum, both compared to C. demersum and to growth rates at intermediate temperatures (18 and 25 °C). 3. The long-term acclimation strategy differed between the two species. Ceratophyllum demersum achieved homeostasis in photosynthesis and respiration rates, and the temperature optimum for photosynthesis changed according to its acclimation temperature. In contrast, C. submersum had a homeostatic response to the ratio of dark respiration to gross photosynthetic capacity and did not change its temperature optimum. Hence, this study highlights key issues that need to be examined carefully to improve models predicting future temperature responses of aquatic plants.

P. Chandra - One of the best experts on this subject based on the ideXlab platform.

  • Response of cadmium to Ceratophyllum demersum L., a rootless submerged plant
    Waste Management, 1999
    Co-Authors: Poonam Gupta, P. Chandra
    Abstract:

    Ceratophyllum demersum, a rootless aquatic plant, was evaluated for its metal-accumulating ability. Plants of C. demersum cultured in 3% Hoagland nutrient medium were supplemented with 0.05, 0.1, 1.0 and 2.0 μg/ml of Cd. Plants showed substantial accumulation of the metal at all concentrations. At 0.05 μg/ml the Concentration factor (Cf) value for Cd was 3027. The high level of tolerance showed by this plant at low concentration may be useful in evaluating its ability in metal abatement programmes.