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排序方式: 共有210条查询结果,搜索用时 15 毫秒
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Semi-natural grasslands are some of the most threatened habitats on the planet, due to the abandonment of small-scale farming and its replacement with intensive agriculture. The fragmented landscape of today has created dispersal limitation that makes improbable the natural dispersal of target species into the remaining patches of grassland. This paper reviews the current status of species introduction into semi-natural grasslands, and summarises the results of published literature in this field. Our review shows that restoration through species introduction is an effective method of establishing dispersal limited species. However, the field of species introduction in restoration ecology has yet to make use of the value that Functional Diversity can add to restoration. No single study in our search has followed up species introduction by measuring any of the currently available indices of functional diversity. This approach is necessary to gain knowledge on what traits are likely to be sorted out in species introduction cases in various environments. 相似文献
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Micha? Wójcik Wiktor Lewandowski Magdalena Król Karol Paw?owski Józef Mieczkowski Roman Lechowski Katarzyna Zabielska 《PloS one》2015,10(4)
BackgroundFeline injection-site sarcomas are malignant skin tumors of mesenchymal origin, the treatment of which is a challenge for veterinary practitioners. Methods of treatment include radical surgery, radiotherapy and chemotherapy. The most commonly used cytostatic drugs are cyclophosphamide, doxorubicin and vincristine. However, the use of cytostatics as adjunctive treatment is limited due to their adverse side-effects, low biodistribution after intravenous administration and multidrug resistance. Colloid gold nanoparticles are promising drug delivery systems to overcome multidrug resistance, which is a main cause of ineffective chemotherapy treatment. The use of colloid gold nanoparticles as building blocks for drug delivery systems is preferred due to ease of surface functionalization with various molecules, chemical stability and their low toxicity.MethodsStability and structure of the glutathione-stabilized gold nanoparticles non-covalently modified with doxorubicin (Au-GSH-Dox) was confirmed using XPS, TEM, FT-IR, SAXRD and SAXS analyses. MTT assay, Annexin V and Propidium Iodide Apoptosis assay and Rhodamine 123 and Verapamil assay were performed on 4 feline fibrosarcoma cell lines (FFS1WAW, FFS1, FFS3, FFS5). Statistical analyses were performed using Graph Pad Prism 5.0 (USA).ResultsA novel approach, glutathione-stabilized gold nanoparticles (4.3 +/- 1.1 nm in diameter) non-covalently modified with doxorubicin (Au-GSH-Dox) was designed and synthesized. A higher cytotoxic effect (p<0.01) of Au-GSH-Dox than that of free doxorubicin has been observed in 3 (FFS1, FFS3, FFS1WAW) out of 4 feline fibrosarcoma cell lines. The effect has been correlated to the activity of glycoprotein P (main efflux pump responsible for multidrug resistance).ConclusionsThe results indicate that Au-GSH-Dox may be a potent new therapeutic agent to increase the efficacy of the drug by overcoming the resistance to doxorubicin in feline fibrosarcoma cell lines. Moreover, as doxorubicin is non-covalently attached to glutathione coated nanoparticles the synthesized system is potentially suitable to a wealth of different drug molecules. 相似文献
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Agata Klimkowska Rudy Van Diggelen Ab P. Grootjans Wiktor Kotowski 《Perspectives in Plant Ecology, Evolution and Systematics》2010,12(3):245-255
The majority of fens in Europe have been transformed for agricultural purposes and have disappeared or become degraded. Fen meadows that developed under low-intensity management of fens also have become degraded. In this paper, we consider the available restoration methods, biotic constraints for restoration and new prospects and approaches for the restoration of severely degraded fens. Due to irreversible changes in landscape settings, hydrology, soil and trophic conditions, a full restoration to natural mires is unlikely. Yet, an improvement of the ecosystem functions and revival of biodiversity in degraded fens is possible. A restoration of semi-natural meadows is one of the alternative targets. Important for restoration efforts to succeed are a sufficient reduction of nutrient levels and preventing acidification. In general, a combination of topsoil removal and seed transfer is an effective measure for fen meadow restoration, provided that groundwater seepage can be re-established. There are also several biotic limitations to fen meadow restoration, due to limited propagule availability of target species and the legacy of the former vegetation in form of its soil seed bank and high seed production by unwanted species. Under the present environmental conditions, the re-development of fen meadows on degraded fens will result in species compositions different from those observed in the past and such restoration may require considerable time and effort. 相似文献
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Habitat protection has been identified as an important strategy for the conservation of woodland caribou (Rangifer tarandus). However, because of the economic opportunity costs associated with protection it is unlikely that all caribou ranges can be protected in their entirety. We used an optimization approach to identify reserve designs for caribou in Alberta, Canada, across a range of potential protection targets. Our designs minimized costs as well as three demographic risk factors: current industrial footprint, presence of white-tailed deer (Odocoileus virginianus), and climate change. We found that, using optimization, 60% of current caribou range can be protected (including 17% in existing parks) while maintaining access to over 98% of the value of resources on public lands. The trade-off between minimizing cost and minimizing demographic risk factors was minimal because the spatial distributions of cost and risk were similar. The prospects for protection are much reduced if protection is directed towards the herds that are most at risk of near-term extirpation. 相似文献
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Jabłońska Ewa Michaelis Dierk Tokarska Marlena Goldstein Klara Grygoruk Mateusz Wilk Mateusz Wyszomirski Tomasz Kotowski Wiktor 《Ecosystems》2020,23(4):730-740
Ecosystems - Mesotrophic rich fens, that is, groundwater-fed mires, may be long-lasting, as well as transient ecosystems, displaced in time by poor fens, bogs, forests or eutrophic reeds. We... 相似文献
100.
Wiktor Kotowski Paulina Dzierża Marek Czerwiński Łukasz Kozub Sylwia Śnieg 《Journal for Nature Conservation》2013,21(5):294-308
Drainage and shrub expansion are the main threats to the biodiversity of fens and fen meadows, whereas rewetting and the removal of shrubby species are frequently applied restoration measures. We examine whether removal of shrubs enhances recovery of target species in a degraded fen subjected to moderate rewetting. The study was located in the drained fen Ca?owanie (central Poland), where remnants of open fen communities and willow-invaded fens exist in former turf-pits, surrounded by degraded meadows on dried peat. All these three habitat types were included in a monitoring grid, which covered an area of 2.2 ha. Within 55 quadrats of 20 m × 20 m we monitored occurrence of 52 species, i.e. two groups of target species (fen indicators and wet meadow indicators) and indicators of two failure scenarios (degraded fen indicators and eutrophic wetland indicators), during six years following shrub removal, rewetting and re-application of conservational mowing, using a 3-step ordinal abundance scale. NMDS ordination revealed a gradual convergence of shrub removal plots and reference plots. We noticed significant effects of year and habitat type on all indicator groups, but only fen indicators have shown a clear (increasing) trend within shrub removal plots. Degraded fen indicators (ruderal and opportunistic species) initially expanded on shrub removal plots, but this effect disappeared in the following years. We conclude that shrub removal enhances establishment of target species in a moderately drained and then rewetted fen and attribute this effect to lowered competition for light. However, given high costs of this method and long-lasting problems with shrub resprouts, we recommend applying shrub removal only to recently overgrown sites, which still retained high botanical diversity. Heavily degraded fen meadows did not react on the increase of moisture, which indicates that more advanced restoration measures, such as top soil removal are needed there. 相似文献