The Experts below are selected from a list of 2397 Experts worldwide ranked by ideXlab platform
D. A. Shitikov - One of the best experts on this subject based on the ideXlab platform.
-
Age-related changes in song repertoire size and song type sharing in the Whinchat Saxicola rubetra
Bioacoustics, 2017Co-Authors: T. M. Vaytina, D. A. ShitikovAbstract:In many oscine passerines males’ songs, the repertoire size increases with age. At the same time it often remains unknown when and where males learn new songs. To infer the Whinchat Saxicola rubetr...
T. M. Vaytina - One of the best experts on this subject based on the ideXlab platform.
-
Age-related changes in song repertoire size and song type sharing in the Whinchat Saxicola rubetra
Bioacoustics, 2017Co-Authors: T. M. Vaytina, D. A. ShitikovAbstract:In many oscine passerines males’ songs, the repertoire size increases with age. At the same time it often remains unknown when and where males learn new songs. To infer the Whinchat Saxicola rubetr...
Michael Wink - One of the best experts on this subject based on the ideXlab platform.
-
Taxonomic status and evolutionary history of the Saxicola torquata complex.
Molecular phylogenetics and evolution, 2009Co-Authors: Robert M. Zink, Michael Wink, Alexandra Pavlova, Sergei V. Drovetski, Sievert RohwerAbstract:We explored variation in mitochondrial ND2 gene sequences from 171 stonechats (Saxicola torquata complex) collected from 27 Eurasian and 3 African localities. We found that two widespread neighboring Eurasian subspecies of Siberian stonechat, Saxicola maura maura and S. m. stejnegeri, although very similar in appearance, are not each other's closest relatives. Eastern Asian S. m. stejnegeri appears to have split from other Palearctic, African, and island stonechats well before differentiation occurred among the latter taxa. Our data indicate that European (S. t. rubicola), central Palearctic (S. m. maura) and eastern Palearctic (S. m. stejnegeri) are independently evolving, and could each warrant separate species status, as assumed earlier for S. rubicola, S. maura and S. torquata. However, we found three localities at which individuals from different major groups occurred. Thus, although these are likely phylogenetic species it is unclear whether they are biological species. There was little phylogeographic structure within the three major Palearctic clades, although samples from Spain might be showing incipient divergence. We maintain that the topology of a mtDNA gene tree is a valid means to discern taxonomic limits.
-
Speciation in the stonechat (Saxicola torquata) inferred from nucleotide sequences of the cytochrome‐b gene
Journal of Zoological Systematics and Evolutionary Research, 2009Co-Authors: U. Wittmann, Michael Wink, P. Heidrich, Eberhard GwinnerAbstract:The geographical differentiation and speciation in the stonechat (Saxicola torquata; Aves: Turdidae) was studied by sequencing a 300–bp fragment of the mitochondrial cytochrome-b gene. Stonechats from three different subspecies inhabiting three continents (S. t. rubicola, the European stonechat; S. t. maura, the Siberian stonechat; and S. t. axillaris, an African stonechat) and stonechats from seven European populations were examined. While variation within the populations of the European subspecies was less than 0.3%, the genetic distances between the subspecies were substantial (2.7–5.7%) in comparison with published data for subspecies of other birds. If speciation is indeed reflected in the cytochrome-b gene of stonechats, species status for the African stonechat, but also for the Siberian taxon, should be reconsidered, especially in the light of differences in distributions, morphology and habitat preference. Zusammenfassung Die genetische Differenzierung des Schwarzkehlchens (Saxicola torquata) abgeleitet von Sequenzen des mitochondriellen Cytochrom b Gens In dieser Studie wurde auf molekularer Ebene die geographische Differenzierung des Schwarzkehlchens (Saxicola torquata; Aves: Turdidae) analysiert, indem 300 bp des mitochondriellen Cytochrom-b Gens sequenziert wurden. Untersucht wurden Schwarzkehlchen, die drei Unterarten auf drei verschiedenen Kontinenten angehoren (S. t. rubicola, das Europaische; S. t. maura, das Sibirische; und S. t. axillaris, ein Afrikanisches Schwarzkehlchen). Die Europaischen Schwarzkehlchen stammten aus sieben verschiedenen Populationen. Wahrend die Variation zwischen den Populationen gering war, war die genetische Distanz zwischen den Unterarten betrachtlich (Sequenzdivergenzen zwischen 2,7 und 5,7%), verglichen mit publizierten Daten anderer Vogeltaxa. Die Autoren sind der Ansicht, das die Unterschiede im Cytochrom-b-Gen dafur sprechen, das die drei Unterarten als Arten betrachtet werden sollten, zumal auch deutliche morphologische Unterschiede vorliegen und die drei Taxa allopatrisch vorkommen.
-
speciation in the stonechat Saxicola torquata inferred from nucleotide sequences of the cytochrome b gene
Journal of Zoological Systematics and Evolutionary Research, 2009Co-Authors: U. Wittmann, Michael Wink, P. Heidrich, Eberhard GwinnerAbstract:The geographical differentiation and speciation in the stonechat (Saxicola torquata; Aves: Turdidae) was studied by sequencing a 300–bp fragment of the mitochondrial cytochrome-b gene. Stonechats from three different subspecies inhabiting three continents (S. t. rubicola, the European stonechat; S. t. maura, the Siberian stonechat; and S. t. axillaris, an African stonechat) and stonechats from seven European populations were examined. While variation within the populations of the European subspecies was less than 0.3%, the genetic distances between the subspecies were substantial (2.7–5.7%) in comparison with published data for subspecies of other birds. If speciation is indeed reflected in the cytochrome-b gene of stonechats, species status for the African stonechat, but also for the Siberian taxon, should be reconsidered, especially in the light of differences in distributions, morphology and habitat preference. Zusammenfassung Die genetische Differenzierung des Schwarzkehlchens (Saxicola torquata) abgeleitet von Sequenzen des mitochondriellen Cytochrom b Gens In dieser Studie wurde auf molekularer Ebene die geographische Differenzierung des Schwarzkehlchens (Saxicola torquata; Aves: Turdidae) analysiert, indem 300 bp des mitochondriellen Cytochrom-b Gens sequenziert wurden. Untersucht wurden Schwarzkehlchen, die drei Unterarten auf drei verschiedenen Kontinenten angehoren (S. t. rubicola, das Europaische; S. t. maura, das Sibirische; und S. t. axillaris, ein Afrikanisches Schwarzkehlchen). Die Europaischen Schwarzkehlchen stammten aus sieben verschiedenen Populationen. Wahrend die Variation zwischen den Populationen gering war, war die genetische Distanz zwischen den Unterarten betrachtlich (Sequenzdivergenzen zwischen 2,7 und 5,7%), verglichen mit publizierten Daten anderer Vogeltaxa. Die Autoren sind der Ansicht, das die Unterschiede im Cytochrom-b-Gen dafur sprechen, das die drei Unterarten als Arten betrachtet werden sollten, zumal auch deutliche morphologische Unterschiede vorliegen und die drei Taxa allopatrisch vorkommen.
-
Distinct taxonomic position of the Madagascar stonechat (Saxicola torquatus sibilla) revealed by nucleotide sequences of mitochondrial DNA
Journal of Ornithology, 2008Co-Authors: Friederike Woog, Michael Wink, Eskandar Rastegar-pouyani, Javier Gonzalez, Barbara HelmAbstract:Stonechats (genus Saxicola ) are passerine birds with an extraordinarily large breeding distribution. Recent studies provide strong evidence that the taxon shows far greater geographic differentiation than originally suspected, with African, Siberian and European stonechats forming distinct, monophyletic groups that have been suggested to be species in their own right. Here, we present additional data on the geographic differentiation among African stonechats, Saxicola torquatus . Nucleotide sequences of the mitochondrial NADH dehydrogenase subunit 2 and cytochrome b genes indicate that the stonechats from Eastern Madagascar ( Saxicola t. sibilla ) form a distinct clade and that they constitute a monophyletic group with stonechats from mainland eastern Africa ( Saxicola t. axillaris ) and La Réunion ( Saxicola tectes ). The genetic and morphological data suggest that the Madagascar stonechat is very likely to be a distinct species, Saxicola sibilla (Linnaeus 1766). However, further studies are needed to verify this. A detailed description of the plumage and various external body measurements is given.
-
Distinct taxonomic position of the Madagascar stonechat (Saxicola torquatus sibilla) revealed by nucleotide sequences of mitochondrial DNA
Journal of Ornithology, 2008Co-Authors: Friederike Woog, Michael Wink, Eskandar Rastegar-pouyani, Javier Gonzalez, Barbara HelmAbstract:Stonechats (genus Saxicola) are passerine birds with an extraordinarily large breeding distribution. Recent studies provide strong evidence that the taxon shows far greater geographic differentiation than originally suspected, with African, Siberian and European stonechats forming distinct, monophyletic groups that have been suggested to be species in their own right. Here, we present additional data on the geographic differentiation among African stonechats, Saxicola torquatus. Nucleotide sequences of the mitochondrial NADH dehydrogenase subunit 2 and cytochrome b genes indicate that the stonechats from Eastern Madagascar (Saxicola t. sibilla) form a distinct clade and that they constitute a monophyletic group with stonechats from mainland eastern Africa (Saxicola t. axillaris) and La Reunion (Saxicola tectes). The genetic and morphological data suggest that the Madagascar stonechat is very likely to be a distinct species, Saxicola sibilla (Linnaeus 1766). However, further studies are needed to verify this. A detailed description of the plumage and various external body measurements is given.
Lin Jiang - One of the best experts on this subject based on the ideXlab platform.
-
Isolation of alkaloids from Corydalis Saxicola by high-speed counter-current chromatography
Zhong yao cai = Zhongyaocai = Journal of Chinese medicinal materials, 2011Co-Authors: Xuanxuan Cheng, Dongmei Wang, Depo Yang, Lin JiangAbstract:OBJECTIVE To develop a method for the rapid isolation of alkaloids from the crude extract of Corydalis Saxicola. METHODS High-speed counter-current chromatography (HSCCC) was applied for the separation of alkaloids from Corydalis Saxicola, with the biphase solvent systems comprised n-butanol-ethyl acetate-water-formic acid (5: 1: 5: 0.01) and n-butanol-ethyl acetate-methanol-water-formic acid (5: 5: 1:9:0.05). RESULTS About 300 mg of crude extract was isolated by HSCCC, yielding 3.6 mg of scoulerine, 9.2 mg of isocorydine, 5.5 mg of dehydrocheilanthifoline, 7.5 mg of dehydrocavidine, 20.4 mg of palmatine and 20.9 mg of berberine, with purities of 71%, 92%, 85%, 76%, 90%, 97%, respectively. CONCLUSION It is time-saving and simple to isolate alkaloids from Corydalis Saxicola by HSCCC with high yields and purities.
-
Study on the influence on the content of dehydrocavidine and total alkaloids in Corydalis Saxicola by different drying methods
Zhong yao cai = Zhongyaocai = Journal of Chinese medicinal materials, 2009Co-Authors: Dongmei Wang, Xuanxuan Cheng, Depo Yang, Zhi Tang, Zhong-fu Wei, Lin JiangAbstract:OBJECTIVE To evaluate the influence of five different drying methods on the contents of dehydrocavidine, a main active constituent, and total alkaloids in Corydalis Saxicola. METHODS The whole plant samples of C. Saxicola were harvested at its florescence stage, and then immediately divided into four parts of root, stem, leaf, and inflorescence. Each part of sample was dried by the following five methods, drying in a sunshine, drying in a shade, oven-drying at 60 degrees C, vacuum-drying at room temperature and frozen vacuum-drying, respectively. Then the contents of dehydrocavidine and total alkaloids were determined by RP-HPLC and ultraviolet spectrophotometry. RESULTS The contents of dehydrocavidine and total alkaloids in all the four parts of the sample processed by drying in a shade were significantly higher than those in the samples processed by the other four drying mehods. CONCLUSION Different drying methods could significantly influence the contents of dehydrocavidine and total alkaloids in C. Saxicola. The process of drying in a shade for a long time would be the best.
-
Simultaneous determination of eight bioactive alkaloids in Corydalis Saxicola by high-performance liquid chromatography coupled with diode array detection.
Phytochemical analysis : PCA, 2008Co-Authors: Xuanxuan Cheng, Dongmei Wang, Lin Jiang, Depo YangAbstract:Corydalis Saxicola Bunting (Papaveraceae), a traditional folk medicine, has been used to treat hepatic diseases for a long time. Owing to its signicant clinical effectiveness against hepatitis, cirrhosis and hepatoma, C. Saxicola and its preparation are widely applied. In this study, eight alkaloids, namely isocorydine, scoulerine, dehydrocheilanthifoline, dehydrodiscretamine, dehydroisoapocavidine, dehydrocavidine, palmatine and berberine, which have been previously proven to possess potential antitumour activity, were selected as the chemical markers of C. Saxicola. To evaluate the quality of C. Saxicola, a simple, accurate and reliable HPLC-DAD method was developed for the simultaneous determination of the above eight compounds. Separation was achieved on a GeminiTM C18 column (5 µm, 250 × 4.6 mm i.d., Phenomenex Inc., CA, USA) with a gradient solvent system of 20 mm aqueous ammonium acetate–acetonitrile, at a flow-rate of 1.0 mL/min and detected at 270 and 280nm. All eight calibration curves showed good linearity (R2 > 0.9992). The method was reproducible with intra- and inter-day variations of less than 5%. The recovery was in the range of 96.09–102.80%. This assay was successfully utilised to quantify the eight alkaloids in C. Saxicola from different locations. The results demonstrated that this method is simple, reliable and suitable for the quality control of this medicinal herb. Copyright © 2008 John Wiley & Sons, Ltd.
-
DNA topoisomerase I inhibitory alkaloids from Corydalis Saxicola.
Chemistry & biodiversity, 2008Co-Authors: Xuanxuan Cheng, Dongmei Wang, Lin Jiang, Depo YangAbstract:Chemical studies of the Chinese herb Corydalis Saxicola Bunting led to the isolation and identification of 14 alkaloids, 1-14. Seven of these compounds, 4-9 and 11, were obtained from this plant for the first time. Feruloylagmatine (7) is the first guanidine-type alkaloid to be identified in the family Papaveraceae and in dicotyledonous plants. All of the isolated compounds were assayed for inhibitory activity against human DNA topoisomerase I. A DNA cleavage assay demonstrated that these alkaloids specifically inhibit topoisomerase through stabilization of the enzyme-DNA complex. Among the isolated alkaloids, (-)-pallidine (8) and (-)-scoulerine (11) showed strong inhibitory activities toward topoisomerase I that were comparable to camptothecin, a typical topoisomerase I inhibitor. A preliminary structure-activity relationship study suggested that the quaternary ammonium ion might play an important role in topoisomerase I inhibition by the isoquinoline alkaloids. These data indicated that DNA topoisomerase I inhibition represents probably one of the anticarcinogenic mechanisms of C. Saxicola.
Wei Dong Zhang - One of the best experts on this subject based on the ideXlab platform.
-
Molecular characterization, recombinant expression in Escherichia coli and biological activity of (S)-Tetrahydroberberine oxidase from Corydalis Saxicola Bunt.
Molecular biology reports, 2011Co-Authors: Keyu Chen, Chang Liu, Junfeng Chen, Ying Xiao, Wei Dong ZhangAbstract:(S)-Tetrahydroberberine [(S)-THB] oxidase is the last enzyme of benzylisoquinoline alkaloids pathway which catalyzes the dehydrogenation of four hydrogen atoms of (S)-THB to produce berberine, the final step of berberine biosynthesis. A (S)-THB gene, designated as Cs(S)-THBO (Genbank accession No. HQ393909), was cloned from a Corydalis Saxicola cDNA library by rapid amplification of cDNA ends. The full-length of cDNA of Cs(S)-THBO was 1127 bp with an open reading frame of 699 bp that predicted to encode a 232-amino acid polypeptide, with a predicted molecular mass of 25.20 kDa. Cs(S)-THBO was the first (S)-THBO gene found in C. Saxicola. Real-time quantitative PCR analysis indicated that Cs(S)-THBO was constitutively expressed in roots, stems, leaves and flowers of C. Saxicola, and with the highest expression level in roots. The results of treatment experiment for plant defense responses revealed that expression of Cs(S)-THBO had a prominent diversity. Recombinant Cs(S)-THBO protein expressed in Escherichia coli strain BL21 (DE3) was active. The results of feeding experiment and HPLC–DAD–ESI–MSn analysis showed that Cs(S)-THBO had the function of catalyzing (S)-tetrahydroberberine to berberine.
-
Tetrahydroprotoberberine alkaloids from Corydalis Saxicola
Chemistry of Natural Compounds, 2007Co-Authors: Hui-liang Li, Wei Dong Zhang, Chuan Zhang, Hai-sheng ChenAbstract:Thirteen tetrahydroprotoberberines, 2,9,10-thrihydroxy-3-methoxytetrahydroprotoberberine (1), cavidine (2), thalictrifoline (3), mesotetrahydrocorysamine (4), stylopine (5), sinactine (6), apocavidine (7), cheilanthifoline (8), 13-β-hydroxystylopine (9), tetrahydropalmatine (10), tetrahydropalmatrubine (11), isocorypalmine (12), and scoulerine (13) have been isolated from the herb of Corydalis. Saxicola Bunting. Of these alkaloids, 2,9,10-thrihydroxy-3-methoxytetrahydroprotoberberine (1) was a new base. The alkaloids mesotetrahydrocorysamine (4), stylopine (5), sinactine (6), apocavidine (7), cheilanthifoline (8), 13-β-hydroxystylopine (9), tetrahydropalmatine (10), tetrahydropalmatrubine (11), isocorypalmine (12), and scoulerine (13), although previously known, were isolated for the first time from Corydalis Saxicola Bunting.
-
Comparative analysis of the chemical profile of wild and cultivated populations of Corydalis Saxicola by high-performance liquid chromatography.
Phytochemical analysis : PCA, 2007Co-Authors: Wei Dong Zhang, Chuan Zhang, Ting Han, Run-hui Liu, Hai-sheng ChenAbstract:Studies on the simultaneous determination and chemical fingerprinting of alkaloids in Corydalis Saxicola Bunting. (Yanhuanglian) were performed for authentication purposes. Ninety samples prepared from different parts of C. Saxicola, including whole plants, roots, stems, leaves and flowers, from wild and cultivated populations, were submitted to quantitative determination and fingerprint analysis. Five major alkaloids, namely, tetradehydroscoulerine, dehydroapocavidine, dehydroisoapocavidine, coptisine and dehydrocavidine, were quantitatively analysed by reversed-phase HPLC with acceptable recoveries (>98.2%). Chemical fingerprinting of C. Saxicola was established and involved 11 markers. The results indicated that there were no obvious differences between the chemical profiles of wild and of cultivated C. Saxicola populations, and that the mean alkaloid contents of the five marker compounds in cultivated populations were significantly higher than those of the wild plants. The highest content of total alkaloids (up to 28.8 mg/g) was found in roots of C. Saxicola. The total alkaloids of the leaves were approximately 50% of those of roots, suggesting that the leaves may be employed as an alternative source of alkaloids. Chemical fingerprints and quantitative HPLC analysis will have a positive impact on the conservation and cultivation of this medicinal plant. Copyright © 2007 John Wiley & Sons, Ltd.
