Virus eradication from some Pelargonium zonale cultivars by meristem-tip culture     

F. A. Hakkaart  Gusta Hartel 《European journal of plant pathology / European Foundation for Plant Pathology》1979,85(2):39-46

On the older leaves ofPelargonium zonale chlorotic rings and flecks are common, especially during spring and fall. From such plants an isometric virus can be isolated that causes local lesions on the leaves ofChenopodium quinoa. An attempt was made to produce symptomless plants, reacting negatively onC. quinoa. Meristem tips on a basal medium supplemented with α-naphthalene acetic acid and coconut milk produced abundant callus, but no plantlets. However, on media containing low concentrations of indole acetic acid and kinetin or benzyl adenine, some plants were produced that fulfilled the above requirements. Those selected on horticultural properties, are considered as valuable mother plants. Of twenty-one cultivars such plants were obtained. They may prove an important contribution to the improvement of theP. zonale industry in the Netherlands.  相似文献   

Standard and Swedish variant types of the hybrid alder Phytophthora attacking alder in Hungary     

Nagy ZA  Bakonyi J  Ersek T 《Pest management science》2003,59(4):484-492

A new Phytophthora disease of common alder (Alnus glutinosa) similar to that previously reported in several countries in Europe has been observed in Hungary. Based on these earlier studies, the alder Phytophthora was considered likely to be a hybrid between P cambivora and a P fragariae-like species: across Europe a range of new alder Phytophthora is spreading that comprise a range of heteroploid hybrids including a 'standard' hybrid type and several other hybrid types termed 'variants'. Phenotypic and molecular features of the pathogen in Hungary were characterised and compared with isolates from elsewhere. The morphologies of five isolates from one region (Hévíz) resembled the common, 'standard' type, whereas the three isolates from another region (Hanság) exhibited traits similar to those of one of the 'variant' types, ie the Swedish 'variant'. Molecular markers of these two groups of Hungarian isolates also represented a good fit to those of the standard type and the Swedish variant, respectively. Isozyme patterns and profiles of restriction fragments of the entire internal transcribed spacer (ITS) region or mitochondrial DNAs and of RAPD-PCR products did not differ within a group, but distinct polymorphisms were exhibited between the two groups of isolates. Southern analysis of random amplified polymorphic DNA (RAPD) revealed the homologous nature of co-migrating bands of P cambivora and the isolates of alder Phytophthora. Furthermore, restriction fragment profiles of the ITS region of ribosomal DNAs and the mtDNAs were consistent with reported biparental origin of alder Phytophthora. The hybrid status of these continuously evolving pathogens raises many issues and challenges concerning efficient control measures.  相似文献   

Graph theory in action: evaluating planned highway tracks based on connectivity measures     

Vera Vasas  Tibor Magura  Ferenc Jordán  Béla Tóthmérész 《Landscape Ecology》2009,24(5):581-586

Maintaining connectivity among local populations in a fragmented landscape is crucial for the survival of many species. For isolated habitat patches, stochastic fluctuations and reduced gene flow can lead to high risk of extinction. The connectivity of the landscape is especially crucial for the carabid species living in the fragmented forests of the Bereg plain (NE Hungary and W Ukraine) because a highway will be constructed through the plain. Our purpose is to (1) evaluate the impacts of three possible highway tracks, (2) suggest a solution that is realistic with less impact on connectivity than other plans and (3) discuss how to decrease the disadvantageous effects of each track. Our results, based on a network analysis of landscape graph of patches and ecological corridors, indicate that the intended highway could have deleterious consequences on forest-living carabids. Relatively simple actions, like the establishment of stepping stones, could compensate for the loss of habitat connectivity and promote the survival of carabids, or minor modifications in one possible track could diminish its adverse effects. While many other studies would be needed for a comprehensive assessment of the biotic impact of the highway, we provide an example on the usefulness of network analysis for land use management. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Temperature shifts induce adaptive changes in the physical state of carp (Cyprinus carpio L.) erythrocyte plasma membranes in vitro     

Indranil Dey  Tibor Farkas 《Fish physiology and biochemistry》1992,10(4):347-355

Blood, freshly collected from warm- and cold-acclimated carp, Cyprinus carpio L., was cooled to 5°C for 4h or warmed to 25°C for 4h, respectively, and the fluorescence anisotropy of washed red blood cells was recorded using the fluorescent dye 3-(p-(6-phenyl-1,3,5-hexatrienyl) phenyl propionic acid [DPH-PA] (which is restricted to the outer leaflet of the plasma membrane) before and after the temperature shift. Despite individual variation, the plasma membrane of cold-exposed erythrocytes became more fluid while that of warm-exposed cells became more rigid following the temperature shift. This response was rapid and reversible. Cold-exposed cells from warm-acclimated fish became more fluid within 40–60 minutes and reverted to their original fluidity within the same time on warming, at a rate of 1°C/min; erythrocytes, from cold-adapted carp displayed an opposite change in fluidity over a similar time period. Cells from warm-acclimated, temperature down-shifted carp hyperfluidized their plasma membranes in the cold, whereas cells from cold-acclimated fish up-shifted in temperature showed no similar effect. These cells showed a complete adjustment of membrane physical state to the temperature. Total phospholipids obtained from warm-acclimated temperature down-shifted cells became more rigid than they were, when assayed at the acclimation temperature. In contrast, phospholipids obtained from cold-acclimated cells became more rigid when exposed to increasing temperatures. No significant changes occurred to the polar head groups, or to the fatty acid composition of the total phospholipids. It was concluded that the lipids play only a secondary role in the control of the physical state of plasma membrane in carp erythrocytes, and that some non-lipid components of these structures might be involved in these regulatory processes.  相似文献   

Factors affecting the persistence of traditional agricultural landscapes in Slovakia during the collectivization of agriculture     

Juraj Lieskovský  Pavol Kenderessy  Jana Špulerová  Tibor Lieskovský  Peter Koleda  Felix Kienast  Urs Gimmi 《Landscape Ecology》2014,29(5):867-877

Collectivization of agriculture (1950s–1970s) was one of the most important periods in landscape development in Slovakia. Traditionally managed agricultural landscapes, that covered more than half of the Slovak territory, were transformed into large-scale fields and only fragments of traditional agricultural landscapes survived. We mapped the remaining traditional agricultural landscapes using aerial photos and historical maps. We then statistically analyzed the various geographical factors and their influence on the transformation process of traditional and collectivized fields, i.e., slope steepness, soil fertility, distance from settlements and isolation from regional capital cities. The comparison was performed using classification tree analysis. We constructed a set of decision rules that explain why fields were managed traditionally or collectivized. Our findings show that traditional agricultural fields were more likely to persist on steep terrain, less fertile soils, and on locations that were closer to the settlements, but more isolated from the regional capital cities. Steepness played the most important role: small-scale fields located on steep areas were not accessible to heavy machinery and therefore, frequently survived the collectivization. We show that the selected geographical factors are good explanatory variables for the collectivization of arable fields and orchards. For vineyards and grasslands, however, the explanatory power of the selected geographical factors is lower, and we suspect that other factors, not depicted in the analysis play an important role.  相似文献   

Effect of cooling rate on nucleation behavior of milk fat--sunflower oil blends.     

S Martini  M L Herrera  R W Hartel 《Journal of agricultural and food chemistry》2001,49(7):3223-3229

The effect of cooling rate on the crystallization behavior of mixes of high-melting milk fat fraction (HMF) and sunflower oil (SFO) was studied by following nucleation with laser-polarized turbidimetry. The initial crystals were photographed, and their thermal and polymorphic behaviors, as well as chemical composition, were investigated by calorimetry, X-ray diffraction, and capillary gas chromatography. Activation energies of nucleation were calculated using the Fisher-Turnbull equation. Despite small differences in Mettler dropping points for different ratios of SFO to HMF, induction times were significantly different between samples and were shorter at a slow cooling rate for the same supercooling. Rapidly cooled samples required more time at crystallization temperature to crystallize than slowly cooled samples because molecular organization prior to nuclei formation took place under different conditions. Regardless of cooling rate or composition, all crystals were in the beta' polymorph. However, morphology, thermal behavior, and chemical composition showed differences with cooling rate. Activation free energies of nucleation were of the same order of magnitude as those published for hydrogenated SFO.  相似文献   

Hungarian priority in network theory     

Braun T 《Science (New York, N.Y.)》2004,304(5678):1745

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Network thinking in riverscape conservation – A graph-based approach     

Tibor Er?s  Dénes Schmera  Robert S. Schick 《Biological conservation》2011,(1):184-192

Graph theoretic approaches have received increased interest recently in landscape planning and conservation in the terrestrial realm, because these approaches facilitate the effective modelling of connectivity among habitats. We examined whether basic principles of graph theory can be extended to other ecosystems. Specifically, we demonstrate how a network-based context can be used for enhancing the more effective conservation of riverine systems. We first show how to use graph theoretic techniques to model riverscapes at the segment level. Then we use a real stream network (Zagyva river basin, Hungary) to examine the topological importance of segments in maintaining riverscape connectivity, using betweenness centrality, a commonly used network measure. Using the undirected graph model of this riverscape, we then prioritize segments for conservation purpose. We examine the value of each of the 93 segments present in the Zagyva river basin by considering the conservation value of local fish assemblages, connectivity and the size of the habitat patches. For this purpose we use the ‘integral index of connectivity’, a recently advocated habitat availability index. Based on the results the selection of the most valuable habitat segments can be optimized depending on conservation resources. Because of their inherent advantage in the consideration of connectivity relationships, we suggest that network analyses offer a simple, yet effective tool for searching for key segments (or junctions) in riverscapes for conservation and environmental management. Further, although the joint consideration of aquatic and terrestrial networks is challenging, the extension of network analyses to freshwater systems may facilitate the more effective selection of priority areas for conservation in continental areas.  相似文献   

Antinociceptive efficacy and plasma concentrations of transdermal buprenorphine in dogs     

Korbinian Pieper  Tibor Schuster  Olivier Levionnois  Ulrike Matis  Alessandra Bergadano 《Veterinary journal (London, England : 1997)》2011,187(3):335-341

To assess the antinociceptive efficacy of transdermal (TD) buprenorphine (B) in dogs, a prospective, positive-controlled experimental study was performed in 10 healthy Beagles. In an open label crossover design, the dogs initially received intravenous B (IVB, 0.02 mg kg^?1) as a positive control, followed by TDB (52.5 μg h^?1) 4 months later. Blood was collected at regular intervals for determination of the plasma concentrations of B ([B]) and its metabolite norbuprenorphine. The antinociceptive efficacy was assessed using thermal and mechanical models of nociception. The peak concentration [B] was 1.54 ng mL^?1 (±1.98) 60 h after TDB application, although three dogs had no measurable [B] after TDB. Maximum thermal threshold (TT) was 52.6 °C (±0.48) at 1 h after IVB administration and 51.63 °C (±1.01) 72 h after TDB application. The significant increase in TT indicated that effective antinociception was achieved beyond 36 h after the application of TDB, lasting until patch removal. There was hysteresis between [B] and the antinociceptive effect.  相似文献   

Physiological changes and defense mechanisms induced by cadmium stress in maize   总被引：2，自引：0，他引：2  

Magda Pl  Eszter Horvth  Tibor Janda  Emil Pldi  Gabriella Szalai 《植物养料与土壤学杂志》2006,169(2):239-246

Heavy metals such as cadmium (Cd) enter the ecosystem chiefly as the result of human activities. Nowadays the heavy‐metal pollution of the soil is causing ever greater problems, exacerbated by the fact that the heavy metals accumulated in plants may, either directly or indirectly, find their way into animals and human beings. Maize is one of the world's most important crops, ranking third after wheat and rice, so the changes induced by one of the most toxic heavy metals, Cd, in maize plants is a cause of some concern. This review discusses not only the toxic symptoms caused by Cd stress, but also the tolerance mechanisms activated in the plants. Cadmium induces a number of physiological changes, such as growth inhibition, changes in the water and ion metabolism, the inhibition of photosynthesis, changes in enzyme activities, and the formation of free radicals. The synthesis and compartmentalization of phytochelatins is induced shortly after the initiation of Cd stress, while other defense mechanisms also play an important role.  相似文献