The Experts below are selected from a list of 33 Experts worldwide ranked by ideXlab platform
Miroslav Flieger - One of the best experts on this subject based on the ideXlab platform.
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Chemoraces and habitat specialization of Claviceps purpurea populations
2000Co-Authors: Sylvie Pažoutova, Marek Linka, Renata Kolinska, Jana Olšovská, Miroslav FliegerAbstract:We studied genetic variability of 100 isolates of Claviceps purpurea by using randomly amplified polymorphic DNA (RAPD), an EcoRI restriction site polymorphism in the 5.8S ribosomal DNA (rDNA), the alkaloids produced, and conidial morphology. We identified three groups: (i) group G1 from fields and open meadows (57 isolates), (ii) group G2 from shady or wet habitats (41 isolates), and (iii) group G3 from Spartina anglica from salt marshes (2 isolates). The sclerotia of G1 isolates contained ergotamines and Ergotoxines; G2 isolates produced ergosine and ergocristine along with small amounts of ergocryptine; and G3 isolates produced ergocristine and ergocryptine. The conidia of G1 isolates were 5 to 8 μm long, the conidia of G2 isolates were 7 to 10 μm long, and the conidia of G3 isolates were 10 to 12 μm long. Sclerotia of the G2 and G3 isolates floated on water. In the 5.8S rDNA analysis, an EcoRI site was found in G1 and G3 isolates but not in G2 isolates. The host preferences of the groups were not absolute, and there were host genera that were common to both G1 and G2; the presence of members of different groups in the same locality was rare. Without the use of RAPD or rDNA polymorphism, it was not possible to distinguish the three groups solely on the basis of phenotype, host, or habitat. In general, populations of C. purpurea are not host specialized, as previously assumed, but they are habitat specialized, and collecting strategies and toxin risk assessments should be changed to reflect this paradigm shift.
Sylvie Pažoutova - One of the best experts on this subject based on the ideXlab platform.
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Chemoraces and habitat specialization of Claviceps purpurea populations
2000Co-Authors: Sylvie Pažoutova, Marek Linka, Renata Kolinska, Jana Olšovská, Miroslav FliegerAbstract:We studied genetic variability of 100 isolates of Claviceps purpurea by using randomly amplified polymorphic DNA (RAPD), an EcoRI restriction site polymorphism in the 5.8S ribosomal DNA (rDNA), the alkaloids produced, and conidial morphology. We identified three groups: (i) group G1 from fields and open meadows (57 isolates), (ii) group G2 from shady or wet habitats (41 isolates), and (iii) group G3 from Spartina anglica from salt marshes (2 isolates). The sclerotia of G1 isolates contained ergotamines and Ergotoxines; G2 isolates produced ergosine and ergocristine along with small amounts of ergocryptine; and G3 isolates produced ergocristine and ergocryptine. The conidia of G1 isolates were 5 to 8 μm long, the conidia of G2 isolates were 7 to 10 μm long, and the conidia of G3 isolates were 10 to 12 μm long. Sclerotia of the G2 and G3 isolates floated on water. In the 5.8S rDNA analysis, an EcoRI site was found in G1 and G3 isolates but not in G2 isolates. The host preferences of the groups were not absolute, and there were host genera that were common to both G1 and G2; the presence of members of different groups in the same locality was rare. Without the use of RAPD or rDNA polymorphism, it was not possible to distinguish the three groups solely on the basis of phenotype, host, or habitat. In general, populations of C. purpurea are not host specialized, as previously assumed, but they are habitat specialized, and collecting strategies and toxin risk assessments should be changed to reflect this paradigm shift.
Irene Nehls - One of the best experts on this subject based on the ideXlab platform.
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Degradation and epimerization of ergot alkaloids after baking and in vitro digestion
2012Co-Authors: Stefan Merkel, Robert Köppen, Ronald Maul, Matthias Koch, Irene NehlsAbstract:The degradation and epimerization of ergot alkaloids (EAs) in rye flour were investigated after baking cookies and subsequently subjecting them to an in vitro digestion model. Different steps of digestion were analyzed using salivary, gastric, and duodenal juices. The degradation and bidirectional conversion of the toxicologically relevant ( R )-epimers and the biologically inactive ( S )-epimers for seven pairs of EAs were determined by a HPLC method coupled with fluorescence detection. Baking cookies resulted in degradation of EAs (2–30 %) and a shift in the epimeric ratio toward the ( S )-epimer for all EAs. The applied digestion model led to a selective toxification of ergotamine and ergosine, two ergotamine-type EAs. The initial percentage of the toxic ( R )-epimer in relation to the total toxin content was considerably increased after digestion of cookies. Ergotamine and ergosine increased from 32 to 51 % and 35 to 55 %, respectively. In contrast, EAs of the Ergotoxine type (ergocornine, α- and β-ergocryptine, and ergocristine) showed an epimeric shift toward their biologically inactive ( S )-epimers. Further experiments indicated that the selective epimerization of ergotamine EAs occurs in the duodenal juice only. These results demonstrate that toxification of EAs in the intestinal tract should be taken into consideration.
J Martinkova - One of the best experts on this subject based on the ideXlab platform.
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disappearance of radioactivity from perfusate of isolated rat liver after administration of different doses of tritiated dh Ergotoxine
1991Co-Authors: I Tilser, J MartinkovaAbstract:In ergot alkaloids a disproportion between the size of the peroral dose and the achieved area under the curve concentrations was described. This process can be explained by nonlinearity in the absorption, distribution or elimination of alkaloids. The aim of the present paper is to find whether elimination of tritiated DH-Ergotoxine (3HDHE) in the liver is a linear, dose-independent process. Therefore on the model of the isolated rat liver disappearance of radioactivity in perfusate after the administration of two doses of 3HDHE, viz. 60 ng g-1 of the liver and 3030 ng g-1 of the liver, was investigated. The disappearance curves of radioactivity expressed as the percentage of the administered dose did not significantly differ between both groups. No significant changes between the groups were found either in the size of pharmacokinetic parameters, or in the portion of the administered radioactivity excreted in bile. Therefore the present authors think that disappearance of radioactivity in perfusate of the isolated liver after administration of 3HDHE is a linear process following first-order kinetics.
Renata Kolinska - One of the best experts on this subject based on the ideXlab platform.
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Chemoraces and habitat specialization of Claviceps purpurea populations
2000Co-Authors: Sylvie Pažoutova, Marek Linka, Renata Kolinska, Jana Olšovská, Miroslav FliegerAbstract:We studied genetic variability of 100 isolates of Claviceps purpurea by using randomly amplified polymorphic DNA (RAPD), an EcoRI restriction site polymorphism in the 5.8S ribosomal DNA (rDNA), the alkaloids produced, and conidial morphology. We identified three groups: (i) group G1 from fields and open meadows (57 isolates), (ii) group G2 from shady or wet habitats (41 isolates), and (iii) group G3 from Spartina anglica from salt marshes (2 isolates). The sclerotia of G1 isolates contained ergotamines and Ergotoxines; G2 isolates produced ergosine and ergocristine along with small amounts of ergocryptine; and G3 isolates produced ergocristine and ergocryptine. The conidia of G1 isolates were 5 to 8 μm long, the conidia of G2 isolates were 7 to 10 μm long, and the conidia of G3 isolates were 10 to 12 μm long. Sclerotia of the G2 and G3 isolates floated on water. In the 5.8S rDNA analysis, an EcoRI site was found in G1 and G3 isolates but not in G2 isolates. The host preferences of the groups were not absolute, and there were host genera that were common to both G1 and G2; the presence of members of different groups in the same locality was rare. Without the use of RAPD or rDNA polymorphism, it was not possible to distinguish the three groups solely on the basis of phenotype, host, or habitat. In general, populations of C. purpurea are not host specialized, as previously assumed, but they are habitat specialized, and collecting strategies and toxin risk assessments should be changed to reflect this paradigm shift.