The Experts below are selected from a list of 1524 Experts worldwide ranked by ideXlab platform

Gottfried Wagner - One of the best experts on this subject based on the ideXlab platform.

  • Heterologous expression and characterization of recombinant phytochrome from the green alga Mougeotia scalaris.
    Photochemistry and Photobiology, 2002
    Co-Authors: Helena J. M. M. Jorissen, Gottfried Wagner, Silvia E. Braslavsky, Wolfgang Gärtner
    Abstract:

    Abstract The full-length apoprotein (124 kDa) and the chromophore-binding N-terminal half (66 kDa) of the phytochrome of the unicellular green alga Mougeotia scalaris have been heterologously expressed in the methylotrophic yeast Pichia pastoris. Assembly with the tetrapyrrole phycocyanobilin (PCB) yielded absorption maxima (for the full-length protein) at 646 and 720 nm for red- and far-red absorbing forms of phytochrome (Pr and Pfr), respectively, whereas the maxima of the N-terminal 66 kDa domain are slightly blueshifted (639 and 714 nm, Pr and Pfr, respectively). Comparison with an action spectrum reported earlier gives evidence that in Mougeotia, as formerly reported for the green alga Mesotaenium caldariorum, PCB constitutes the genuine chromophore. The full-length protein, when converted into its Pfr form and kept in the dark, reverted rapidly into the Pr form (lifetimes of 1 and 24 min, ambient temperature), whereas the truncated chromopeptide (66 kDa construct) was more stable and converted into ...

  • cloning recombinant expression and characterization of wild type 105 trp calmodulin of the green alga Mougeotia scalaris
    Botanica Acta, 1998
    Co-Authors: Chr Zörb, Katja D. Brunner, Markus Perbandt, Chr Betzel, Gottfried Wagner
    Abstract:

    : The single calmodulin gene (CaM) of the green alga Mougeotia scalaris (Hassall) was cloned, sequenced and the CDNA inserted into the prokaryotic expression vector pGEX-2T. The recombinant calmodulin protein (CAM) was expressed as a fusion product together with glutathione S-transferase and isolated on glutathione sepharose. After cleavage and purification, the CaM was characterized by Ca2+-dependent shift in SDS-PAGE, by activation of cyclic 3′,5′nucleotide phosphodiesterase (PDE) and sensitivity to the inhibitors trifluoperazine and calmidazolium, with native Mougeotia CaM as control. Using Ca2+ buffers in the PDE test, affinity to Ca2+ of Mougeotia CaM was found to be diminished fivefold compared to maize or bovine brain CaMs. There was also a 20-fold increase of half maximal activation (Kact) in the PDE test for Mougeotia CaM relative to maize CaM, while the Kact of maize CaM to that of bovine brain CaM was almost the same. The derived amino acid sequences of CaM from Mougeotia and Zea mays revealed three major conservative amino acid exchanges, including unique 105-Trp (Mougeotia) Leu (maize). In Mougeotia CaM the 105-Trp, including the neighbouring side chains of 92-Phe and 141-Phe, putatively form a hydrophobic ring interaction, as revealed by molecular modelling.

  • Cloning, Recombinant Expression and Characterization of Wild Type‐105‐Trp‐Calmodulin of the Green Alga Mougeotia scalaris
    Botanica Acta, 1998
    Co-Authors: Chr Zörb, Katja D. Brunner, Markus Perbandt, Chr Betzel, Gottfried Wagner
    Abstract:

    : The single calmodulin gene (CaM) of the green alga Mougeotia scalaris (Hassall) was cloned, sequenced and the CDNA inserted into the prokaryotic expression vector pGEX-2T. The recombinant calmodulin protein (CAM) was expressed as a fusion product together with glutathione S-transferase and isolated on glutathione sepharose. After cleavage and purification, the CaM was characterized by Ca2+-dependent shift in SDS-PAGE, by activation of cyclic 3′,5′nucleotide phosphodiesterase (PDE) and sensitivity to the inhibitors trifluoperazine and calmidazolium, with native Mougeotia CaM as control. Using Ca2+ buffers in the PDE test, affinity to Ca2+ of Mougeotia CaM was found to be diminished fivefold compared to maize or bovine brain CaMs. There was also a 20-fold increase of half maximal activation (Kact) in the PDE test for Mougeotia CaM relative to maize CaM, while the Kact of maize CaM to that of bovine brain CaM was almost the same. The derived amino acid sequences of CaM from Mougeotia and Zea mays revealed three major conservative amino acid exchanges, including unique 105-Trp (Mougeotia) Leu (maize). In Mougeotia CaM the 105-Trp, including the neighbouring side chains of 92-Phe and 141-Phe, putatively form a hydrophobic ring interaction, as revealed by molecular modelling.

  • High irradiance blue light affects cortical microtubules in the green alga Mougeotia scalaris
    Plant and Cell Physiology, 1997
    Co-Authors: Bashir Al-rawass, Franz Grolig, Gottfried Wagner
    Abstract:

    High irradiance blue light (HIBL), but not red light, diminished anti-tubulin indirect immunofluorescence of cortical microtubules in the green alga Mougeotia. Quantitation of MT-specific immunofluorescence by digital image analysis revealed taxol to counteract the HIBL-elicited decrease in immunolabelling. Taxol caused no significant increase of immunofluorescence in red light.

  • Phytochrome of the green alga Mougeotia: cDNA sequence, autoregulation and phylogenetic position
    Plant Molecular Biology, 1996
    Co-Authors: Armin Winands, Gottfried Wagner
    Abstract:

    A cDNA clone encoding phytochrome (apoprotein) of the zygnematophycean green alga Mougeotia scalaris has been isolated and sequenced. The clone consisted of 3372 bp, encoded 1124 amino acids, and showed strain-specific nucleotide exchanges for M. scalaris , originating from different habitats. No indication was found of multiple phytochrome genes in Mougeotia . The 5′ non-coding region of the Mougeotia PHY cDNA harbours a striking stem-loop structure. Homologies with higher-plant phytochromes were 52–53% for PHYA and 57–59% for PHYB. Highest homology scores were found with lower-plant phytochromes, for example 67% for Selaginella (Lycopodiopsida), 64% for Physcomitrella (Bryopsida) and 73% for Mesotaenium (Zygnematophyceae). In an unrooted phylogenetic tree, the position of Mougeotia PHY appeared most distant to all other known PHYs. The amino acids Gly-Val in the chromophore-binding domain (-Arg- Gly-Val -His-Gly-Cys-) were characteristic of the zygnematophycean PHYs known to date. There was no indication of a transmembrane region in Mougeotia phytochrome in particular, but a carboxyl-terminal 16-mer three-fold repeat in both, Mougeotia and Mesotaenium PHYs may represent a microtubule-binding domain. Unexpected for a non-angiosperm phytochrome, its expression was autoregulated in Mougeotia in a red/far-red reversible manner: under P_r conditions, phytochrome mRNA levels were tenfold higher than under P_fr conditions.

Ulrike Obertegger - One of the best experts on this subject based on the ideXlab platform.

  • There to stay: invasive filamentous green alga Mougeotia in Lake Kinneret, Israel
    Hydrobiologia, 2019
    Co-Authors: Tamar Zohary, Ora Hadas, Alla Alster, Ulrike Obertegger
    Abstract:

    Mougeotia (Zygnematales, Charophyta) first appeared in the plankton of Lake Kinneret in 1998. While initially rare, from 2004 onwards it was present in the plankton continuously, forming massive blooms in spring (2005, 2006, 2012) or in winter (2010), occasionally appearing in different morphological and life cycle forms. Mougeotia maintained its population under a wide range of water temperatures, nutrient concentrations, solar radiation, pH levels and stratification patterns, making it a highly versatile alga. In multiple regression, year and month as the only predictors explained 36% of the pattern of Mougeotia biomass. However, Mougeotia biomass could not be explained by any of the environmental parameters considered. Modeling the temporal dynamics of Mougeotia biomass using an autoregressive integrated moving average (ARIMA(1,0,0)) explained 56% of variability indicating that intraspecific factors (e.g., competition for nutrients or self-shading) may determine the dynamics of Mougeotia biomass. To explain the lack of relationships with the environmental parameters, we hypothesize that (1) Mougeotia possesses exceptional physiological plasticity and/or (2) Lake Kinneret may host two or more genetically distinct cryptic species of Mougeotia with different environmental niches. Both explanations may hinder any inference on Mougeotia– environment relationships and require confirmation by experimental work.

Tamar Zohary - One of the best experts on this subject based on the ideXlab platform.

  • There to stay: invasive filamentous green alga Mougeotia in Lake Kinneret, Israel
    Hydrobiologia, 2019
    Co-Authors: Tamar Zohary, Ora Hadas, Alla Alster, Ulrike Obertegger
    Abstract:

    Mougeotia (Zygnematales, Charophyta) first appeared in the plankton of Lake Kinneret in 1998. While initially rare, from 2004 onwards it was present in the plankton continuously, forming massive blooms in spring (2005, 2006, 2012) or in winter (2010), occasionally appearing in different morphological and life cycle forms. Mougeotia maintained its population under a wide range of water temperatures, nutrient concentrations, solar radiation, pH levels and stratification patterns, making it a highly versatile alga. In multiple regression, year and month as the only predictors explained 36% of the pattern of Mougeotia biomass. However, Mougeotia biomass could not be explained by any of the environmental parameters considered. Modeling the temporal dynamics of Mougeotia biomass using an autoregressive integrated moving average (ARIMA(1,0,0)) explained 56% of variability indicating that intraspecific factors (e.g., competition for nutrients or self-shading) may determine the dynamics of Mougeotia biomass. To explain the lack of relationships with the environmental parameters, we hypothesize that (1) Mougeotia possesses exceptional physiological plasticity and/or (2) Lake Kinneret may host two or more genetically distinct cryptic species of Mougeotia with different environmental niches. Both explanations may hinder any inference on Mougeotia– environment relationships and require confirmation by experimental work.

  • Occurrence and mass development of Mougeotia spp. (Zygnemataceae) in large, deep lakes
    Hydrobiologia, 2015
    Co-Authors: Kálmán Tapolczai, Tamar Zohary, Orlane Anneville, Judit Padisák, Nico Salmaso, Giuseppe Morabito, Rémy D. Tadonléké, Frédéric Rimet
    Abstract:

    Over the last decades, mass developments by the filamentous conjugating green alga Mougeotia have been followed in three large peri-alpine lakes (Lake Geneva, Lake Garda, Lake Maggiore) and in the sub-tropical Lake Kinneret. The aim of this study is to highlight annual and interannual patterns of Mougeotia biomass in the studied lakes and select key environmental parameters that may favour and maintain its mass development. Our results confirm former studies that planktic Mougeotia favours meso-oligotrophic conditions and becomes dominant when annual mean total phosphorus concentrations in the epilimnion fall below 20 µg l^−1. This triggering factor has effect with interactions of other environmental circumstances such as the water column stability. Physiological and morphological features of the taxon make it a successful competitor under stratified conditions. Results also showed that in three out of the four studied lakes, the annual peak was higher when the annual population development started earlier. Focusing on Lake Geneva, depth and strength of the thermocline, as well as wind speed in the beginning of summer that can cause nutrient replenishment and mix the epilimnion are key factors in the blooming of the taxon.

Jose Baudilio Rondon - One of the best experts on this subject based on the ideXlab platform.

Adrienne R. Hardham - One of the best experts on this subject based on the ideXlab platform.

  • Capacity for microtubule reorganization and cell wall synthesis in cytoplasts of the green algaMougeotia
    Protoplasma, 1994
    Co-Authors: M. E. Galway, G. J. Hyde, Adrienne R. Hardham
    Abstract:

    A small proportion of nucleate subprotoplasts (karyoplasts) and enucleate subprotoplasts (cytoplasts) are formed during the preparation of protoplasts from the filamentous green alga Mougeotia . Regeneration of Mougeotia protoplasts is an orderly process known to involve reorganisation of cortical microtubules into polar arrays centered upon two opposing foci, synthesis of new cell walls and elongation to reform cylindrical cells. The ability of cytoplasts to carry out microtubule reorganisation and cell wall synthesis was investigated by combining Hoechst staining, to distinguish cytoplasts from karyoplasts and protoplasts, with immunofluorescent staining of microtubules and Calcofluor or Tinopal staining of cell walls. Cytoplasts survived at least 20 h in culture, but did not elongate. However, cytoplasts did participate in the first steps of protoplast regeneration. The majority of cytoplasts synthesized some cell wall material, while a small proportion was able to form ordered arrays of cortical microtubules indistinguishable from those in regenerating nucleate protoplasts. These results demonstrate the ability of plant microtubules to form new, orderly arrays in the absence of a nucleus, and suggest that the reestablishment of axiality in the protoplasts does not require a nucleus or nuclear DNA transcription.

  • Capacity for microtubule reorganization and cell wall synthesis in cytoplasts of the green alga Mougeotia
    Protoplasma, 1994
    Co-Authors: M. E. Galway, G. J. Hyde, Adrienne R. Hardham
    Abstract:

    Sunnnary. A small proportion of nucleate subprotoplasts (karyoplasts) and enucleate subprotoptasts (cytoplasts) are formed during the preparation ofprotoplasts from the filamentous green alga Mougeotia. Regeneration of Mougeotia protoplasts is an orderly process known to involve reorganisation of cortical microtubules into polar arrays centered upon two opposing foci, synthesis of new cell walls and elongation to reform cylindrical cells. The ability of cytoplasts to carry out microtubule reorganisation and cell wall synthesis was investigated by combining Hoechst staining, to distinguish cytoplasts from karyoplasts and protoplasts, with immunofluorescent of microtubules and Calcofiuor or Tinopal staining of cell walls. Cytoplasts survived at least 20 h in culture, but did not elongate. However, cytoplasts did participate in the first steps of protoplast regeneration. The majority of cytoplasts synthesized some cell wall material, while a small proportion was able to form ordered arrays of cortical microtubules indistinguishable from those in regenerating nucleate protoplasts. These results demonstrate the ability of plant microtubules to form new, orderly arrays in the absence of a nucleus, and suggest that the reestablishment of axiality in the protoplasts does not require a nucleus or nuclear DNA transcription.