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Several Plants (several + plant)

Distribution by Scientific Domains
Medical Sciences40%
Life Sciences40%

Terms modified by Several Plants

  • several plant species
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    Selected Abstracts

    Metacommunity patterns of highly diverse stream midges: gradients, chequerboards, and nestedness, or is there only randomness?

    ECOLOGICAL ENTOMOLOGY, Issue 5 2005
    Jani Heino
    Abstract., 1.,Several non-random patterns in the distribution of species have been observed, including Clementsian gradients, Gleasonian gradients, nestedness, chequerboards, and evenly spaced gradients. Few studies have examined these patterns simultaneously, although they have often been studied in isolation and contrasted with random distribution of species across sites. 2.,This study examined whether assemblages of chironomid midges exhibit any of the idealised distribution patterns as opposed to random distribution of species across sites within the metacommunity context in a boreal drainage system. Analyses were based on stream surveys conducted during three consecutive years. Analytical approaches included ordinations, cluster analysis, null models, and associated randomisation methods. 3.,Midge assemblages did not conform to Clementsian gradients, which was evidenced by the absence of clearly definable assemblage types with numerous species exclusive to each assemblage type. Rather, there were signs of continuous Gleasonian variability of assemblage composition, as well as significant nested subset patterns of species distribution. 4.,Midge assemblages showed only weak relationships with any of the measured environmental variables, and even these weak environmental relationships varied among years. 5.,Midge assemblages did not appear to be structured by competition. This finding was somewhat problematic, however, because the two indices measuring co-occurrence provided rather different signs of distribution patterns. This was probably a consequence of how they actually measure co-occurrence. 6.,Although midge assemblages did not show a perfect match with any of the idealised distribution patterns, they nevertheless showed a resemblance to the empirical patterns found previously for several plant and animal groups. [source]

    Glacial vicariance in the Pacific Northwest: evidence from a lodgepole pine mitochondrial DNA minisatellite for multiple genetically distinct and widely separated refugia

    MOLECULAR ECOLOGY, Issue 10 2008
    JULIE GODBOUT
    Abstract The Canadian side of the Pacific Northwest was almost entirely covered by ice during the last glacial maximum, which has induced vicariance and genetic population structure for several plant and animal taxa. Lodgepole pine (Pinus contorta Dougl. ex. Loud.) has a wide latitudinal and longitudinal distribution in the Pacific Northwest. Our main objective was to identify relictual signatures of glacial vicariance in the population structure of the species and search for evidence of distinct glacial refugia in the Pacific Northwest. A maternally inherited mitochondrial DNA minisatellite-like marker was used to decipher haplotype diversity in 91 populations of lodgepole pine located across the natural range. Overall population differentiation was sizeable (GST = 0.365 and RST = 0.568). Four relatively homogeneous groups of populations, possibly representative of as many genetically distinct glacial populations, were identified for the two main subspecies, ssp. latifolia and ssp. contorta. For ssp. contorta, one glacial lineage is suggested to have been located at high latitudes and possibly off the coast of mainland British Columbia (BC), while the other is considered to have been located south of the ice sheet along the Pacific coast. For ssp. latifolia, two genetically distinct glacial populations probably occurred south of the ice sheet: in the area bounded by the Cascades and Rocky Mountains ranges, and on the eastern side of the Rockies. A possible fifth refugium located in the Yukon may have also been present for ssp. latifolia. Zones of contact between these ancestral lineages were also apparent in interior and northern BC. These results indicate the role of the Queen Charlotte Islands and the Alexander Archipelago as a refugial zone for some Pacific Northwest species and the vicariant role played by the Cascades and the American Rocky Mountains during glaciation. [source]

    Strategies for the Synthesis of Stemona Alkaloids,

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 15 2009
    Ramon Alibés
    Abstract The extracts of several plants of the Stemonaceae family have long been used in Asian countries against differentdiseases and for their antiparasitic properties. Significant constituents of these extracts are a series of structurally related secondary metabolites named Stemona alkaloids. All the Stemona alkaloids are polycyclic and contain multiple stereocenters. Most of them present a central pyrrolo[1,2- a]azepine system and the majority also incorporate at least one ,-methyl-,-butyrolactone substructure. Their challenging molecular architectures have motivated the development of new strategies for the construction of their skeletons, but only a small number of total syntheses have been published and they are still limited to quite a small number of targets. This microreview briefly examines most of the synthetic approaches to these alkaloids, according to the strategies devised to assemble their intricate structures, stressing the main similarities and differences encountered in the work developed by different laboratories, as well as the variations introduced along the synthetic route when pursuing different alkaloids through a common strategy. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

    Contact allergy and medicinal herbs

    JOURNAL DER DEUTSCHEN DERMATOLOGISCHEN GESELLSCHAFT, Issue 1 2008
    Werner Aberer
    Summary Herbal treatments are becoming increasingly popular, and are often used for internal as well as dermatological conditions, both externally as well as orally. The prevalence of contact sensitization against several plants especially of the Compositae family is quite high in Europe. Sensitization seems to occur relatively frequent with a few species such as arnica, elecampane and tea tree (oil), and occurs rarely with the majority. Testing for plant allergy is problematic because of the limited number of commercially available standardized patch test substances and the danger of active sensitization when testing with plants, parts thereof, or individual extracts. Knowledge about the allergic potential of plants is limited. Although plants are regarded as critical allergens by dermatologists, the number of reported cases of contact dermatitis is relatively small.Many widely used substances are not licensed as drugs or cosmet-ics. While the positive effects are frequently questionable or limited, the side effects are often more evident. Adverse effects of herbal medicines are an important albeit neglected subject in dermatology, which deserves further systematic investigation. [source]

    Effect of a combination of extract from several plants on Cell-mediated and humoral immunity of patients with advanced ovarian cancer

    PHYTOTHERAPY RESEARCH, Issue 5 2006
    N. Kormosh
    Abstract The influence of a plant preparation AdMax (Nulab Inc., Clearwater, FL, USA) on immunity in ovarian cancer patients was studied. The preparation is a combination of dried ethanol/water extracts from roots of Leuzea carthamoides, Rhodiola rosea, Eleutherococcus senticosus and fruits of Schizandra chinensis. Twenty eight patients with stage III,IV epithelial ovarian cancer were treated once with 75 mg/m2 cisplatin and 600 mg/m2 cyclophosphamide. Peripheral blood was collected 4 weeks after the chemotherapy. Subclasses of T, B and NK lymphocytes were tested for in the blood samples: CD3, CD4, CD5, CD7, CD8, CD11B, CD16, CD20, CD25, CD38, CD45RA, CD50, CD71 and CD95. Immunoglobulin G, A and M concentrations were also determined. Changes were observed in the following T cell subclasses: CD3, CD4, CD5 and CD8. In patients who took AdMax (270 mg a day) for 4 weeks following the chemotherapy, the mean numbers of the four T cell subclasses were increased in comparison with the mean numbers of the T cell subclasses in patients who did not take AdMax. In patients who took AdMax, the mean amounts of IgG and IgM were also increased. The obtained results suggest that the combination of extracts from adaptogenic plants may boost the suppressed immunity in ovarian cancer patients who are subject to chemotherapy. Copyright © 2006 John Wiley & Sons, Ltd. [source]