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911.
Åke Örström 《Protoplasma》1932,15(1):566-589
Ohne ZusammenfassungFür die Anregung zu dieser Arbeit und den damit zusammenhangenden theoretischen Betrachtungen spreche ich Herrn Professor J. Runnström meinen wärmsten Dank aus. Frau Professor A. Runnström, die mit unermüdlicher Geduld die Arbeit erleichtert hat, danke ich aufs herzlichste.Die Arbeit ist wahrend des Sommers 1931 in der Station Biologique zu Roscoff (Frankreich) ausgeftihrt worden.Dem Direktor der Station in Roscoff, Herrn Professor Oh. Pérez, sowie dem Unterdirektor Herrn Dr. Gr. Teissier spreche ich meinen besten Dank aus für die Überlassung des Arbeitsplatzes und ihr wohlwollendes Entgegenkommen während der Zeit meines dortigen Aufenthalts.Die Unkosten der Untersuchungen wurden von der Lars Hiertas Minne-Stiftung bestritten. 相似文献
912.
913.
Mari Moora John Davison Maarja Öpik Riccardo Bommarco Helge Bruelheide Ingolf Kühn William E. Kunin Madis Metsis Alo Vanatoa Elise Vanatoa Jane C. Stout Merilin Truusa Martin Zobel Gian‐Reto Walther 《Journal of Biogeography》2011,38(7):1305-1317
Aim The biogeography of arbuscular mycorrhizal (AM) fungi is poorly understood, and consequently the potential of AM fungi to determine plant distribution has been largely overlooked. We aimed to describe AM fungal communities associating with a single host‐plant species across a wide geographical area, including the plant’s native, invasive and experimentally introduced ranges. We hypothesized that an alien AM plant associates primarily with the geographically widespread generalist AM fungal taxa present in a novel range. Location Europe, China. Methods We transplanted the palm Trachycarpus fortunei into nine European sites where it does not occur as a native species, into one site where it is naturalized (Switzerland), and into one glasshouse site. We harvested plant roots after two seasons. In addition, we sampled palms at three sites in the plant’s native range (China). Roots were subjected to DNA extraction, polymerase chain reaction (PCR) and 454 sequencing of AM fungal sequences. We analysed fungal communities with non‐metric multidimensional scaling (NMDS) ordination and cluster analysis and studied the frequency of geographically widespread fungal taxa with log‐linear analysis. We compared fungal communities in the roots of the palm with those in resident plants at one site in the introduced range (Estonia) where natural AM fungal communities had previously been studied. Results We recorded a total of 73 AM fungal taxa. AM fungal communities in the native and introduced ranges differed from one another, while those in the invasive range contained taxa present in both other ranges. Geographically widespread AM fungal taxa were over‐represented in palm roots in all regions, but especially in the introduced range. At the Estonian site, the palm was colonized by the same community of widespread AM fungal taxa as associate with resident habitat‐generalist plants; by contrast, resident forest‐specialist plants were colonized by a diverse community of widespread and other AM fungal taxa. Main conclusions AM fungal communities in the native, invasive and experimentally introduced ranges varied in taxonomic composition and richness, but they shared a pool of geographically widespread, non‐host‐specific taxa that might support the invasion of a generalist alien plant. Our dataset provides the first geographical overview of AM taxon distributions obtained using a single host‐plant species. 相似文献
914.
Surface water contamination from agricultural and urban runoff and wastewater discharges from industrial and municipal activities
is of major concern to people worldwide. Classical models can be insufficient to visualise the results because the water quality
variables used to describe dynamic pollution sources are complex, multivariable, and nonlinearly related. Artificial intelligence
techniques with the ability to analyse multivariant water quality data by means of a sophisticated visualisation capacity
can offer an alternative to current models. In this study, the Kohonen self-organising feature maps (SOM) neural network was
initially applied to analyse the complex nonlinear relationships among multivariable surface water quality variables using
the component planes of the variables to determine the complex behaviour of water quality parameters. The dependencies between
water quality variables were extracted and interpreted using the pattern analysis visualised in component planes. For further
investigation, the k-means clustering algorithm was used to determine the optimal number of clusters by partitioning the maps
and utilising the Davies–Bouldin clustering index, leading to seven groups or clusters corresponding to water quality variables.
The results reveal that the concentrations of Na, K, Cl, NH4-N, NO2-N, o-PO4, component planes of organic matter (pV), and dissolved oxygen (DO) were significantly affected by seasonal changes, and
that the SOM technique is an efficient tool with which to analyse and determine the complex behaviour of multidimensional
surface water quality data. These results suggest that this technique could also be applied to other environmentally sensitive
areas such as air and groundwater pollution. 相似文献
915.
916.
İsmail Yapıcı Ahmet Altay Beyza Öztürk Sarıkaya Mustafa Korkmaz Alptuğ Atila İlhami Gülçin Ekrem Köksal 《化学与生物多样性》2021,18(3):e2000812
In this study, phenolic composition, and in vitro biological activities of ethyl acetate (EAE) and methanol (ME) extracts obtained from the aerial parts of endemic Tanacetum erzincanense were investigated. Total phenolic and flavonoid content of the extracts were determined by Folin-Ciocalteu and aluminum chloride colorimetric methods, respectively. Antioxidant capacity of the extracts was evaluated over radical scavenging (DPPH and ABTS) and metal ion reducing power (FRAP and CUPRAC) tests. Individual phenolic compounds in ME was analyzed by high-performance liquid chromatography coupled to electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF/MS). Cell inhibitory potential of the extracts was tested against colorectal adenocarcinoma (HT-29), breast adenocarcinoma (MCF-7), and hepatocarcinoma (HepG2) cells by 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay. The results showed that ME contains higher TPC (64.4 mg GAE/g) and TFC (62.2 mg QE/g) than those of EAE (41.5 mg GAE/g and 40.0 mg QE/g). LC-ESI-QTOF/MS analysis revealed that ME is rich in phenolic compounds, namely, chlorogenic acid, apigenin, quercetin, luteolin, and diosmetin. Antioxidant assay results indicated that ME possess stronger activity than EAE and a power that competes with synthetic antioxidants. XTT assay results demonstrated that although both extracts displayed a considerable cytotoxicity against the tested cancer cell lines in a time and dose-dependent manner, ME expressed its selective inhibitory action towards MCF-7 cells with an IC50 value of 20.4 μg/mL for 72 h. These results may serve as a basis for further in vivo studies to examine the potential applications of T. erzincanense in food and pharmaceutical industries. 相似文献
917.
Variable fluorescence (Fv) of intact leaves was measured whenthe temperature was lowered at a rate of 12?C per mn,from 20?C to 20?C. The quantum flux density of the excitinglight was 12 µE m2 sec1 in orderto sensitize F only at 20?C. The fluorescence yield decreasedrapidly at the freezing point of the leaf and upon further coolingthe fluorescence yield increased again. Fm was obtained a fewdegrees below the freezing point. Repeated freeze-thaw cycles caused successively increased damageto the thylakoid membranes on either the oxidizing or the reducingside of photosystem II. An eventual loss of Fv over Fo was typicalfor damage on the water splitting side of photosystem II, whereasdamage after the primary electron acceptor Q of photosystemII was characterized by an invariable fluorescence yield atFm over the temperature range examined. (Received January 18, 1982; Accepted June 12, 1982) 相似文献
918.
Crystal Structure of Human Carbonic Anhydrase C 总被引:16,自引:0,他引:16
A. LILJAS K. K. KANNAN P.-C. BERGSTÉN I. WAARA K. FRIDBORG B. STRANDBERG U. CARLBOM L. JÄRUP S. LÖVGREN M. PETEF 《Nature: New biology》1972,235(57):131-137
The three dimensional structure of human carbonic anhydrase C has been determined at 2.0 Å resolution. The active site has been identified by the binding of inhibitors and the location of the zinc ion. 相似文献
919.
920.