The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Oddur Vilhelmsson - One of the best experts on this subject based on the ideXlab platform.
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the total and active bacterial community of the chlorolichen Cetraria islandica and its response to long term warming in sub arctic tundra
Frontiers in Microbiology, 2020Co-Authors: Ingeborg J Klarenberg, Christoph Keuschnig, Denis Warshan, Ingibjorg S Jonsdottir, Oddur VilhelmssonAbstract:Lichens are traditionally defined as a symbiosis between a fungus and a green alga and or a cyanobacterium. This idea has been challenged by the discovery of bacterial communities inhabiting the lichen thalli. These bacteria are thought to contribute to the survival of lichens under extreme and changing environmental conditions. How these changing environmental conditions affect the lichen-associated bacterial community composition remains unclear. We describe the total (rDNA-based) and potentially metabolically active (rRNA-based) bacterial community of the lichen Cetaria islandica and its response to long-term warming using a 20-year warming experiment in an Icelandic sub-Arctic tundra. 16S rRNA and rDNA amplicon sequencing showed that the orders Acetobacterales (of the class Alphaproteobacteria) and Acidobacteriales (of the phylum Acidobacteria) dominated the bacterial community. Numerous amplicon sequence variants (ASVs) could only be detected in the potentially active community but not in the total community. Long-term warming led to increases in relative abundance of bacterial taxa on class, order and ASV level. Warming altered the relative abundance of ASVs of the most common bacterial genera, such as Granulicella and Endobacter. The potentially metabolically active bacterial community was also more responsive to warming than the total community. Our results suggest that the bacterial community of the lichen C. islandica is dominated by acidophilic taxa and harbors disproportionally active rare taxa. We also show for the first time that climate warming can lead to shifts in lichen-associated bacterial community composition.
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the total and active bacterial community of the chlorolichen Cetraria islandica and its response to long term warming in sub arctic tundra
bioRxiv, 2020Co-Authors: Ingeborg J Klarenberg, Christoph Keuschnig, Denis Warshan, Ingibjorg S Jonsdottir, Oddur VilhelmssonAbstract:Abstract Lichens are traditionally defined as a symbiosis between a fungus and a green alga and or a cyanobacterium. This idea has been challenged by the discovery of bacterial communities inhabiting the lichen thalli. These bacteria are thought to contribute to the survival of lichens under extreme and changing environmental conditions. How these changing environmental conditions affect the lichen-associated bacterial community composition remains unclear. We describe the total (rDNA-based) and potentially metabolically active (rRNA-based) bacterial community of the lichen Cetaria islandica and its response to long-term warming using a 20-year warming experiment in an Icelandic sub-Arctic tundra. 16S rRNA and rDNA amplicon sequencing showed that the orders Acetobacterales (of the class Alphaproteobacteria) and Acidobacteriales (of the phylum Acidobacteria) dominated the bacterial community. Numerous ASVs (amplicon sequence variants) taxa could only be detected in the potentially active community but not in the total community. Long-term warming led to increases in relative abundance on class, order and ASV level. Warming altered the relative abundance of ASVs of the most common bacterial genera, such as Granulicella and Endobacter. The potentially metabolically active bacterial community was also more responsive to warming than the total community. Our results suggest that the bacterial community of the lichen C. islandica is dominated by acidophilic taxa and harbors disproportionally active rare taxa. We also show for the first time that climate warming can lead to shifts in lichen-associated bacterial community composition.
K Ingolfsdottir - One of the best experts on this subject based on the ideXlab platform.
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Immunomodulating polysaccharides from aqueous extracts of Cetraria islandica (Iceland moss)
Phytomedicine, 2011Co-Authors: K Ingolfsdottir, K. Jurcic, H WagnerAbstract:Several polysaccharide fractions, isolated from a hot aqueous extract of Cetraria islandica (L.) Ach. by ethanol fractionation and ion-exchange chromatography, exerted significant in vitro anti-complementary activity and pronounced enhancement of in vitro granulocytic phagocytosis. Prior to aqueous extraction, low molecular weight compounds were removed from the plant material by organic extraction. An aqueous extract, prepared by the traditional method of briefly boiling the lichen directly with water, also exhibited significant anti-complementary and enhanced phagocytic activity. When tested for reticuloendothelial phagocytic activity in the in vivo carbon clearance test, the extract gave rise to a significant increase in the rate of colloidal carbon elimination. Results show, that in addition to an immunostimulating alkali-soluble galactomannan previously isolated from Iceland moss, the plant also contains water soluble polysaccharides, extractable by traditional methods, which exert immunomodulating effects.
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immunologically active 1 3 1 4 α d glucan from Cetraria islandica
Phytomedicine, 1999Co-Authors: E S Olafsdottir, K. Jurcic, K Ingolfsdottir, Hilde Barsett, Smestad B Paulsen, Hildebert WagnerAbstract:Summary A polysaccharide, Ci-3, resembling isolichenan except with a much higher degree of polymerization, has been isolated from the water extract, as well as from the alkali extract, of the lichen Cetraria islandica (L.) using ethanol fractionation, dialysis, ion-exchange chromatography and gel filtration. The mean Mr of Ci-3 was determined to be 2000 kD, compared to 6–8 kD reported for isolichenan. The structure of Ci-3 was elucidated and found to be composed of (1→3)- and (l→4)-α-D-glucopyranosyl units in the ratio of 2:1, using methanolysis, methylation analysis, optical rotation and NMR spectroscopy. The immunomodulating activity of Ci-3 was tested in an in vitro phagocytosis assay and anti-complementary, and proved to be active in both tests.
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In vitro susceptibility of Helicobacter pylori to protolichesterinic acid from the lichen Cetraria islandica.
Antimicrobial agents and chemotherapy, 1997Co-Authors: K Ingolfsdottir, G.a. Gudjónsdóttir, Martha Á. Hjálmarsdóttir, A Sigurdsson, A Brynjolfsdottir, Ólafur SteingrímssonAbstract:With reference to the traditional use of Cetraria islandica (Iceland moss) for relief of gastric and duodenal ulcer, plant extracts were screened for in vitro activity against Helicobacter pylori. (+)-Protolichesterinic acid, an aliphatic alpha-methylene-gamma-lactone, was identified as an active component. The MIC range of protolichesterinic acid, in free as well as salt form, was 16 to 64 micrograms/ml.
Carla Roselli - One of the best experts on this subject based on the ideXlab platform.
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elemental and radiological characterization of commercial Cetraria islandica l acharius pharmaceutical and food supplementation products
Science of The Total Environment, 2018Co-Authors: Maria Assunta Meli, Donatella Desideri, C. Cantaluppi, F. Ceccotto, Laura Feduzi, Carla RoselliAbstract:An elemental and radiological characterization was performed on Cetraria islandica (L.) Ach. pharmaceutical and food supplementation products purchased in local specialty shops in Italy. Essential elements (K, Ca, P, S, Cl, Mn, Fe, Cu, Zn, Ni, Br, I) and nonessential or toxic elements (Al, Ti, Si, Rb, Sr, As, Cd, Sn, and Pb) were determined by Energy Dispersive Polarized X-Ray Fluorescence Spectrometry; natural radionuclides (238U, 234U, 230Th, 210Po, 232Th, and 228Th) were determined by alpha spectrometry. The results show that C. islandica, whose nutritional value was assessed referring to recommended nutrient intakes, could serve as an important source of essential elements. Moreover, as expected, lichens concentrate airborne 210Po, whose activity ranged from 132 to 489Bqkg-1dw. This value was much higher than those reported by UNSCEAR for leafy vegetables in the world. In addition, total As and Cd were <1mgkg-1dw and Pb mean concentration was 9.25mgkg-1dw. Health risks associated with the toxic elements contained in C. islandica (L.) products were calculated using risk estimators. Their contribution to total elemental intake does not appear to pose a threat, but the concentrations of these elements should be continuously monitored to protect consumers against potential adverse health effects.
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Elemental and radiological characterization of commercial Cetraria islandica (L.) Acharius pharmaceutical and food supplementation products.
The Science of the total environment, 2017Co-Authors: Maria Assunta Meli, Donatella Desideri, C. Cantaluppi, F. Ceccotto, Laura Feduzi, Carla RoselliAbstract:An elemental and radiological characterization was performed on Cetraria islandica (L.) Ach. pharmaceutical and food supplementation products purchased in local specialty shops in Italy. Essential elements (K, Ca, P, S, Cl, Mn, Fe, Cu, Zn, Ni, Br, I) and nonessential or toxic elements (Al, Ti, Si, Rb, Sr, As, Cd, Sn, and Pb) were determined by Energy Dispersive Polarized X-Ray Fluorescence Spectrometry; natural radionuclides (238U, 234U, 230Th, 210Po, 232Th, and 228Th) were determined by alpha spectrometry. The results show that C. islandica, whose nutritional value was assessed referring to recommended nutrient intakes, could serve as an important source of essential elements. Moreover, as expected, lichens concentrate airborne 210Po, whose activity ranged from 132 to 489Bqkg-1dw. This value was much higher than those reported by UNSCEAR for leafy vegetables in the world. In addition, total As and Cd were
K. Jurcic - One of the best experts on this subject based on the ideXlab platform.
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Immunomodulating polysaccharides from aqueous extracts of Cetraria islandica (Iceland moss)
Phytomedicine, 2011Co-Authors: K Ingolfsdottir, K. Jurcic, H WagnerAbstract:Several polysaccharide fractions, isolated from a hot aqueous extract of Cetraria islandica (L.) Ach. by ethanol fractionation and ion-exchange chromatography, exerted significant in vitro anti-complementary activity and pronounced enhancement of in vitro granulocytic phagocytosis. Prior to aqueous extraction, low molecular weight compounds were removed from the plant material by organic extraction. An aqueous extract, prepared by the traditional method of briefly boiling the lichen directly with water, also exhibited significant anti-complementary and enhanced phagocytic activity. When tested for reticuloendothelial phagocytic activity in the in vivo carbon clearance test, the extract gave rise to a significant increase in the rate of colloidal carbon elimination. Results show, that in addition to an immunostimulating alkali-soluble galactomannan previously isolated from Iceland moss, the plant also contains water soluble polysaccharides, extractable by traditional methods, which exert immunomodulating effects.
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immunologically active 1 3 1 4 α d glucan from Cetraria islandica
Phytomedicine, 1999Co-Authors: E S Olafsdottir, K. Jurcic, K Ingolfsdottir, Hilde Barsett, Smestad B Paulsen, Hildebert WagnerAbstract:Summary A polysaccharide, Ci-3, resembling isolichenan except with a much higher degree of polymerization, has been isolated from the water extract, as well as from the alkali extract, of the lichen Cetraria islandica (L.) using ethanol fractionation, dialysis, ion-exchange chromatography and gel filtration. The mean Mr of Ci-3 was determined to be 2000 kD, compared to 6–8 kD reported for isolichenan. The structure of Ci-3 was elucidated and found to be composed of (1→3)- and (l→4)-α-D-glucopyranosyl units in the ratio of 2:1, using methanolysis, methylation analysis, optical rotation and NMR spectroscopy. The immunomodulating activity of Ci-3 was tested in an in vitro phagocytosis assay and anti-complementary, and proved to be active in both tests.
Ingeborg J Klarenberg - One of the best experts on this subject based on the ideXlab platform.
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the total and active bacterial community of the chlorolichen Cetraria islandica and its response to long term warming in sub arctic tundra
Frontiers in Microbiology, 2020Co-Authors: Ingeborg J Klarenberg, Christoph Keuschnig, Denis Warshan, Ingibjorg S Jonsdottir, Oddur VilhelmssonAbstract:Lichens are traditionally defined as a symbiosis between a fungus and a green alga and or a cyanobacterium. This idea has been challenged by the discovery of bacterial communities inhabiting the lichen thalli. These bacteria are thought to contribute to the survival of lichens under extreme and changing environmental conditions. How these changing environmental conditions affect the lichen-associated bacterial community composition remains unclear. We describe the total (rDNA-based) and potentially metabolically active (rRNA-based) bacterial community of the lichen Cetaria islandica and its response to long-term warming using a 20-year warming experiment in an Icelandic sub-Arctic tundra. 16S rRNA and rDNA amplicon sequencing showed that the orders Acetobacterales (of the class Alphaproteobacteria) and Acidobacteriales (of the phylum Acidobacteria) dominated the bacterial community. Numerous amplicon sequence variants (ASVs) could only be detected in the potentially active community but not in the total community. Long-term warming led to increases in relative abundance of bacterial taxa on class, order and ASV level. Warming altered the relative abundance of ASVs of the most common bacterial genera, such as Granulicella and Endobacter. The potentially metabolically active bacterial community was also more responsive to warming than the total community. Our results suggest that the bacterial community of the lichen C. islandica is dominated by acidophilic taxa and harbors disproportionally active rare taxa. We also show for the first time that climate warming can lead to shifts in lichen-associated bacterial community composition.
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the total and active bacterial community of the chlorolichen Cetraria islandica and its response to long term warming in sub arctic tundra
bioRxiv, 2020Co-Authors: Ingeborg J Klarenberg, Christoph Keuschnig, Denis Warshan, Ingibjorg S Jonsdottir, Oddur VilhelmssonAbstract:Abstract Lichens are traditionally defined as a symbiosis between a fungus and a green alga and or a cyanobacterium. This idea has been challenged by the discovery of bacterial communities inhabiting the lichen thalli. These bacteria are thought to contribute to the survival of lichens under extreme and changing environmental conditions. How these changing environmental conditions affect the lichen-associated bacterial community composition remains unclear. We describe the total (rDNA-based) and potentially metabolically active (rRNA-based) bacterial community of the lichen Cetaria islandica and its response to long-term warming using a 20-year warming experiment in an Icelandic sub-Arctic tundra. 16S rRNA and rDNA amplicon sequencing showed that the orders Acetobacterales (of the class Alphaproteobacteria) and Acidobacteriales (of the phylum Acidobacteria) dominated the bacterial community. Numerous ASVs (amplicon sequence variants) taxa could only be detected in the potentially active community but not in the total community. Long-term warming led to increases in relative abundance on class, order and ASV level. Warming altered the relative abundance of ASVs of the most common bacterial genera, such as Granulicella and Endobacter. The potentially metabolically active bacterial community was also more responsive to warming than the total community. Our results suggest that the bacterial community of the lichen C. islandica is dominated by acidophilic taxa and harbors disproportionally active rare taxa. We also show for the first time that climate warming can lead to shifts in lichen-associated bacterial community composition.