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Tectaria moranii (Tectariaceae), a new fern species from Costa Rica
No full textA new fern species, Tectaria moranii (sect. Tectaria; Tectariaceae), is described from central Costa Rica. Tectaria moranii is most similar to T. vivipara in having rachis bulbils, but the two are distinguishable by the habit of rhizome, shape of lamina, petiole and rachis color, proliferability of rachis bulbils, number of pairs of pinnae per lamina, pinna width, and sorus distribution. Tectaria moranii is assigned LC-Least Concern category following the IUCN guidelines
DNAzyme based visual detection of DNA methylation
No full textA novel colorimetric method which utilizes DNAzyme as a signal reporter was developed for DNA methylation detection. As low as 1/10(6) of methylated DNA could be successfully detected from unmethylated DNA. The discrimination ability is at least two orders of magnitude better than that of the methylation specific PCR
Evolutionary history of the angiosperm flora of China
No full textHigh species diversity may result from recent rapid speciation in a 'cradle' and/or the gradual accumulation and preservation of species over time in a 'museum'(1,2). China harbours nearly 10% of angiosperm species worldwide and has long been considered as both a museum, owing to the presence of many species with hypothesized ancient origins(3,4), and a cradle, as many lineages have originated as recent topographic changes and climatic shifts-such as the formation of the Qinghai-Tibetan Plateau and the development of the monsoon-provided new habitats that promoted remarkable radiation(5). However, no detailed phylogenetic study has addressed when and how the major components of the Chinese angiosperm flora assembled to form the present-day vegetation. Here we investigate the spatio-temporal divergence patterns of the Chinese flora using a dated phylogeny of 92% of the angiosperm genera for the region, a nearly complete species-level tree comprising 26,978 species and detailed spatial distribution data. We found that 66% of the angiosperm genera in China did not originate until early in the Miocene epoch (23 million years ago (Mya)). The flora of eastern China bears a signature of older divergence (mean divergence times of 22.04-25.39 Mya), phylogenetic overdispersion (spatial co-occurrence of distant relatives) and higher phylogenetic diversity. In western China, the flora shows more recent divergence (mean divergence times of 15.29-18.86 Mya), pronounced phylogenetic clustering (co-occurrence of close relatives) and lower phylogenetic diversity. Analyses of species-level phylogenetic diversity using simulated branch lengths yielded results similar to genus-level patterns. Our analyses indicate that eastern China represents a floristic museum, and western China an evolutionary cradle, for herbaceous genera; eastern China has served as both a museum and a cradle for woody genera. These results identify areas of high species richness and phylogenetic diversity, and provide a foundation on which to build conservation efforts in China
ANALYSIS ON ENRICHMENT OF AQUATIC PLANTS RESPONSE TO DIFFERENT HEAVY METAL IONS IN POLLUTED WATER TAKING DUCKWEED AS AN EXAMPLE
No full textIn order to improve the quality of water, the enrichment of different heavy metal ions by aquatic plants is studied taking duckweed as an example The site of the experiment is in Sichuan University of China, mainly from the following aspects of research: the heavy metal content in water, the heavy metal content in duckweed, chlorophyll content, adsorption capacity of Cadmium ions in different concentrations of nitric acid solution, enrichment capacity of Cadmium ion and the relationship between heavy metal content in duckweed and that of water. The study shows that the aquatic plants such as duckweed have a strong enrichment to Cu, Pb and Zn in the complex water body of heavy metals Cu, Pb and Zn, and their enrichment ability is higher than that of the water plants. With the increase of Cd2+ concentration, the content of chlorophyll a and b in duckweed decreased significantly, and the decline is increased with the increase of Cd2+ concentration. In 3 mg/L Cadmium nitrate solution, duckweed has a maximum absorption rate of Cd2+ reaching 87%, the adsorption of duckweed decreased with increasing concentration and the enrichment of Cd2+ in duckweed showed a nonmonotonic curve with the increase of treatment time. The concentration of Cd2+ in the duckweed of 8d reached the maximum value (1.6 mg/g), and the concentration of Cd2+ is reduced in the 9-12d duckweed, the concentration of heavy metals in water is significantly correlated with the concentration of Cu, Pb, Zn and Mn in aquatic plants duckweed. The method can effectively analyze the supposed enrichment. The sensitivity of duckweed can be used to detect changes of heavy metals in water, which can be used as an bioindicator of environmental pollution. At the same time, the accuracy of heavy metal determination by this method is high
Thiourea-catalyzed asymmetric domino Michael-cyclization reaction of 3-isothiocyanato oxindoles with beta,gamma-unsaturated alpha-keto esters for the synthesis of spirocyclic oxindoles
No full textA reaction between 3-isothiocyanato oxindoles and beta,gamma-unsaturated alpha-keto esters catalyzed by a chiral thiourea organocatalyst via a domino Michael-cyclization process is described, which delivers a range of biologically important 2'-thioxospiro[indoline-3,4'-oxazolidin]-2-one compounds in high yields with good diastereo- and enantioselectivities (up to 99% yield, >99:1 dr, >99% ee). Moreover, two of 2'-thioxospiro[indoline-3,4'-oxazolidin]-2-one compounds were found to significantly behave in antiinflammatory activities in a preliminary biological evaluation. (C) 2019 Published by Elsevier Ltd
Monoamine oxidase B immobilized on magnetic nanoparticles for screening of the enzyme's inhibitors from herbal extracts
No full textMonoamine oxidase B (MAO-B) was for the first time immobilized on magnetic nanoparticles to be used for screening of MAO-B inhibitors from herbal extracts. The immobilized enzyme was characterized with transmission electronic microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, and vibrating sample magnetometer. The immobilized enzyme retained 95% of the activity, while the thermostability was significantly increased. It was then used as solid phase extraction absorbent to extract MAO-B's ligands from two traditional Chinese medicinal plants, Cortex fraxini and Pericarpium granati. Calceolarioside B and ellagic acid were extracted from C. fraxini and P. granati, respectively, and both of them were found to be inhibitors of MAO-B with IC50 of 40.95 +/- 0.63 and 103.70 +/- 2.34 mu M, respectively. This is the first report that calceolarioside B inhibits MAO-B activity. Furthermore, inhibitory mechanisms of both compounds were studied by molecular docking analysis, the results of which demonstrated that the affinity of calceolarioside B with monoamine oxidase B was stronger than that of ellagic acid. The method proposed in this work is highly efficient for screening of MAO-B inhibitors from complex mixtures, showing great potential in discovering anti-Parkinson's disease compounds present in medicinal plants
Grassland production in response to changes in biological metrics over the Tibetan Plateau
No full textA clear interannual variability in annual production of grasslands (termed AEVI) has been reported over the Tibetan Plateau (TP), but the underlying mechanism has not been fully understood. Here, we explained the interannual variability of AEVI during 2001-2015 by two phenological metrics (the start and end of the growing season, termed SOS and EOS, respectively) and one physiological metric (the maximum capacity of canopy light absorbance, termed MEVI) using MODIS Enhanced Vegetation Index (EVI) data over the TP. The results showed that the interannual variability of AEVI can be well attributed to not only the trends of, but also the sensitivities of AEVI to, the selected biological metrics. On the one hand, the advancing SOS and delaying EOS dominated the study area while both increased and decreased MEVI were observed. On the other hand, the AEVI responded negatively to the SOS and positively to the EOS and MEVI, exhibiting significant variations along the temperature and precipitation gradients. Hence, the current interannual variability of SOS and EOS mainly increased the AEVI; meanwhile, both enhancement and suppression of the interannual variability of MEVI to the AEVI were widespread over the TP. Overall, the interannual variability of MEVI mostly contributed to that of the AEVI, indicating a dominant role of the physiological metric rather than phenological metrics in carbon gain of TP grasslands. The achievements of this study are helpful to understand the underlying biological causes of the interannual variability of grassland production over the TP. (C) 2019 Elsevier B.V. All rights reserved
ANALYSIS ON ENRICHMENT OF AQUATIC PLANTS RESPONSE TO DIFFERENT HEAVY METAL IONS IN POLLUTED WATER TAKING DUCKWEED AS AN EXAMPLE
No full textIn order to improve the quality of water, the enrichment of different heavy metal ions by aquatic plants is studied taking duckweed as an example The site of the experiment is in Sichuan University of China, mainly from the following aspects of research: the heavy metal content in water, the heavy metal content in duckweed, chlorophyll content, adsorption capacity of Cadmium ions in different concentrations of nitric acid solution, enrichment capacity of Cadmium ion and the relationship between heavy metal content in duckweed and that of water. The study shows that the aquatic plants such as duckweed have a strong enrichment to Cu, Pb and Zn in the complex water body of heavy metals Cu, Pb and Zn, and their enrichment ability is higher than that of the water plants. With the increase of Cd2+ concentration, the content of chlorophyll a and b in duckweed decreased significantly, and the decline is increased with the increase of Cd2+ concentration. In 3 mg/L Cadmium nitrate solution, duckweed has a maximum absorption rate of Cd2+ reaching 87%, the adsorption of duckweed decreased with increasing concentration and the enrichment of Cd2+ in duckweed showed a nonmonotonic curve with the increase of treatment time. The concentration of Cd2+ in the duckweed of 8d reached the maximum value (1.6 mg/g), and the concentration of Cd2+ is reduced in the 9-12d duckweed, the concentration of heavy metals in water is significantly correlated with the concentration of Cu, Pb, Zn and Mn in aquatic plants duckweed. The method can effectively analyze the supposed enrichment. The sensitivity of duckweed can be used to detect changes of heavy metals in water, which can be used as an bioindicator of environmental pollution. At the same time, the accuracy of heavy metal determination by this method is high
Taxonomic re-evaluation of the monotypic genus Pararhabdophis Bourret, 1934 (Squamata: Colubridae: Natricinae) with discovery of its type species, P. chapaensis, from China
No full textThe Asian monotypic genus Pararhabdophis Bourret, 1934 has long been known from a single holotype of the type species Pararhabdophis chapaensis Bourret, 1934 only. The limited available information hampered the identification of the natricine species. On the basis of eight newly collected specimens of P. chapaensis from the type locality in Sa Pa, Lao Cai Province, Vietnam and from Pingbian, Yunnan Province in southwestern China, the taxonomic position of the genus Pararhabdophis was re-evaluated using both morphological and molecular datasets for the first time. Pararhabdophis chapaensis is nested within the genus Hebius Thompson, 1913 with strong support, and morphologically indistinguishable from the latter genus. As a consequence, we herein synonymize the genus Pararhabdophis with Hebius and discuss about the existing paraphyly of some Hebius species. In addition we report Hebius chapaensis for the first time from China and provide redescription and natural history data of this poorly known species. To facilitate future taxonomic work, an identification key to all known natricine genera from China and Vietnam is also provided
Synthesis of asymmetrical thioethers with sulfinamides as the sulfenylation agent under metal-free conditions
No full textUsing sulfinamides as a new reagent for preparation of asymmetrical thioethers has been developed under metal-free conditions. The reactions proceeded smoothly without the use of stinky thiophenol, highly toxic sulfonyl chloride or oxidant. Such a simple, efficient transformation provides an attractive approach to various diaryl sulfides in good to excellent yields. (C) 2018 Elsevier Ltd. All rights reserved