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71.
? Context
Secondary Norway spruce forests in the Western Beskids are among the most damaged forests in Europe. Although spruce bark beetle (Ips typographus) has been recently causing large-scale damage to these forests, our understanding of I. typographus dynamics in this environment is inadequate for evaluating forest sustainability.? Aim
This study aims to evaluate the patterns of damage caused by I. typographus to spruce forests with compromised ecological stability.? Methods
Forest infestation by I. typographus was inferred from sanitary felling data collected from 1998 to 2004. Stand and site data were obtained from forest management plans. Spatial-dependence analysis, ordinary kriging and neural network-based regression modelling were used to investigate the patterns of infestation and the casual relationships in the studied ecosystem.? Results
I. typographus long-distance dispersal substantially decreased with outbreak culmination. The spread of infestation was only weakly related to stand and site parameters. Infestations spread isotropically at the stand and patch level but directionally at the regional scale.? Conclusions
The large-scale spread of infestation can be explained by the uniform age and species composition of the investigated forests and by the ability of populations to overwhelm suboptimal trees. The observations presented here suggest that secondary spruce forests in Europe may be unsustainable due to unprecedented bark beetle outbreaks, which can be further amplified by changing climate. 相似文献72.
Trine H Jensen Gitte Ajjouri Kurt J Handberg Marek J Slomka Vivien J Coward Martine Cherbonnel Véronique Jestin Peter Lind Poul H J?rgensen 《Acta veterinaria Scandinavica》2013,55(1):84
Background
Avian influenza virus (AIV) subtypes H5 and H7 attracts particular attention because of the risk of their potential pathogenicity in poultry. The haemagglutination inhibition (HI) test is widely used as subtype specific test for serological diagnostics despite the laborious nature of this method. However, enzyme-linked immunosorbent assays (ELISAs) are being explored as an alternative test method.H5 and H7 specific monoclonal antibodies were experimentally raised and used in the development of inhibition ELISAs for detection of serological response specifically directed against AIV subtypes H5 and H7. The ELISAs were evaluated with polyclonal chicken anti-AIV antibodies against AIV subtypes: H1N2, H5N2, H5N7, H7N1, H7N7, H9N9, H10N4 and H16N3.Results
Both the H5 and H7 ELISA proved to have a high sensitivity and specificity and the ELISAs detected H5 and H7 antibodies earlier during experimental infection than the HI test did. The reproducibility of the ELISA’s performed at different times was high with Pearson correlation coefficients of 0.96-0.98.Conclusions
The ELISAs are a potential alternative to the HI test for screening of large amounts of avian sera, although only experimental sera were tested in this study. 相似文献73.
Stloukal P Kucharczyk P Sedlarik V Bazant P Koutny M 《Journal of agricultural and food chemistry》2012,60(16):4111-4119
The preemergence chloroacetamide herbicide metazachlor was encapsulated in biodegradable low molecular weight poly(lactic acid) micro- and submicroparticles, and its release to the water environment was investigated. Three series of particles, S, M, and L, varying in their size (from 0.6 to 8 μm) and with various initial amounts of the active agent (5%, 10%, 20%, 30% w/w) were prepared by the oil-in-water solvent evaporation technique with gelatin as biodegradable surfactant. The encapsulation efficiencies reached were about 60% and appeared to be lower for smaller particles. Generally, it was found that the rate of herbicide release decreased with increasing size of particles. After 30 days the portions of the herbicide released for its highest loading (30% w/w) were 92%, 56%, and 34% for about 0.6, 0.8, and 8 μm particles, respectively. The release rates were also lower for lower herbicide loadings. Metazachlor release from larger particles tended to be a diffusion-controlled process, while for smaller particles the kinetics was strongly influenced by an initial burst release. 相似文献
74.
Vesely Tomas Neuberg Marek Trakal Lukas Szakova Jiřina Tlustoa Pavel 《Water, air, and soil pollution》2012,223(4):1847-1859
The effects of one of the most toxic heavy metals, lead (Pb), applied in two different concentrations and combined with chelate
application were investigated on the water macrophyte (Pistia stratiotes L.) physiology. The influences were observed by the chlorophyll and free amino acid content determination. Also the lead
accumulation in macrophyte biomass was investigated to assess the potential efficiency of this plant for rhizofiltration of
highly Pb-polluted water. Na EDTA and Na citrate were used as chelates and Pb(NO3)2 as lead supplement. The application of organic chelates simulated conditions of an induced phytoextraction process. Statistical
analyses were performed as a one-way ANOVA with a subsequent Tukey HSD test at a level of P < 0.05. Pb contents in both root and leaf tissues gradually increased with increasing Pb concentrations in the nutrient solution.
More lead was accumulated in leaves than in roots within all treatments. The total chlorophyll content decreased with increased
Pb concentration and with a higher content of chelates. The chelate addition increased the total amino acid content in leaves
but decreased the total amino acid content in roots. The addition of lead with chelates decreased the dry biomass weight.
However, water macrophyte showed extremely high lead accumulation in biomass in the short term (up to 8 days) and this accumulation
potential could be used for relatively fast and effective decrease of high concentration of this risk element in contaminated
water or sewage. 相似文献
75.
76.
The role of Ca2+ and Na+ membrane transport in brook trout (Salvelinus fontinalis) spermatozoa motility 总被引:1,自引:0,他引:1
Olga Bondarenko Borys Dzyuba Jacky Cosson Marek Rodina Otomar Linhart 《Fish physiology and biochemistry》2014,40(5):1417-1421
The role of environmental ion composition and osmolality in Ca2+ signaled activation was assessed in spermatozoa of brook trout Salvelinus fontinalis. Milt from ten mature males was obtained by abdominal massage. Spermatozoa motility was evaluated in 0, 100, and 300 mOsm/kg NaCl or sucrose solutions, buffered by 10 mM Tris–HCl pH 8.5. For investigation of spermatozoa reaction to external Ca2+ concentration, 2 mM ethylene glycol tetraacetic acid (EGTA) was added to the activation media as a calcium ions chelator. For investigation of the effect of external Na+ concentration in conditions of low external Ca2+, 100 µM amiloride was added to the EGTA-containing solutions as a Na+ transport blocker. Low motility was observed in sucrose (Na+ free) solutions containing 2 mM EGTA but not in Na+ solutions containing 2 mM EGTA. Addition of amiloride led to significantly increased motility (P < 0.05) compared with sucrose (Na+ free) solutions containing 2 mM EGTA. We conclude that Na+ transport in Ca2+-free solutions plays a regulatory role in brook trout spermatozoa activation. The influence of competitive Na+ and Ca2+ transport on the control of spermatozoa activation requires further study with respect to its application for improvement of artificial activation and storage media. 相似文献
77.
Aleš Lebeda Barbora Mieslerová Marek Petřivalský Lenka Luhová Martina Špundová Michaela Sedlářová Vladimíra Nožková-Hlaváčková David A. C. Pink 《European journal of plant pathology / European Foundation for Plant Pathology》2014,138(3):569-596
Tomato powdery mildew (Oidium neolycopersici) is one of the most devastating diseases of cultivated tomatoes worldwide. Although the first epidemics were recorded more than 25 years ago many aspects of this host-pathogen interaction are still not well understood. Detailed morphological and molecular studies of the anamorphs confirmed that O. neolycopersici is phylogeneticaly close to Erysiphe aquilegiae var. ranunculi. Host range is rather broad, apart from Solanaceae hosts were found in the families Apocynaceae, Campanulaceae, Crassulaceae, Cistaceae, Cucurbitaceae, Linaceae, Malvaceae, Papaveraceae, Pedialiaceae, Scrophulariaceae, Valerianaceae a Violaceae. Non-host resistance within these families is not based on inhibition of formation of primary haustorium, however, on post-haustorial hypersensitive reponse and another type of non-hypersensitive resistance. Screening of wild Solanum species (previous Lycopersicon spp.) germplasm revealed valuable sources of resistance (S. habrochaites, S. pennellii, S. cheesmaniae, S. chilense, S. peruvianum). The main resistance mechanism was found to be a hypersensitive response (HR), in some cases followed by limited development of the pathogen. However, there is a broad variation in resistance response on the histological and cytological level. Interaction between many wild Solanum spp. and O. neolycopersici is race-specific, at least three races were differentiated. In some interspecific crosses (S. lycopersicum × S. habrochaites) adult plant resistance was observed. Biochemical studies focusing on production of reactive oxygen species (ROS) and peroxidase activity during infection of O. neolycopersici showed that production of ROS and activity of corresponding enzymes is related to activation of defence responses in genotypes of wild Solanum sect. Lycopersicon. The significance of nitric oxide (NO) in O. neolycopersici pathogenesis was supported by experiments with NO donors and scavengers. In moderately resistant genotype S. chmielewskii, treatment by heat stress caused slight deceleration of pathogen development, increased production of jasmonic acid (JA) and abscisic acid (ABA) and increased peroxidase activity in infected plants. The different degree of tomato resistance/susceptibility did not markedly change the rate and extent of photosynthetic response to O. neolycopersici; only minimal impairment of photosynthesis was found in both susceptible and moderately resistant genotypes during the first 9 days after inoculation. The accumulated evidence confirm a crucial role of localised increased production of ROS and reactive nitrogen species (RNS) in response to pathogen penetration into plant tissue and its involvement in the plant resistance responses including the initiation and progression of plant cell death in host wild Solanum species. Crucial points of further research are discussed. 相似文献
78.
Sera from 335 farmed fallow deer (Dama dama) at the breeding station in Kosewo Górne in the Mazurian Lake District, North-East Poland, were investigated for the presence of antibodies against Neospora caninum. The distribution of age groups was as follow: >4 years - 154 animals; 2 years - 76 animals; 1 year - 105 animals. Ten sera with the optical density exceeding 0.159 absorbance units (i.e., cut-off value) in ELISA test were also analyzed by Western blot. Western blot analysis revealed seroreactivity against immunodominant N. caninum antigens of 37, 25, and 16kDa; however, in some sera additional bands were also visible. This is the first screening studies for antibodies against N. caninum in farmed fallow deer in Poland, in the region where neosporosis was confirmed in cattle and in farmed and free-ranging European red deer (Cervus elaphus). 相似文献
79.
80.
Rebecca Ibach Marek Gnatowski Grace Sun Jessie Glaeser Mathew Leung John Haight 《Wood material science & engineering》2018,13(2):81-96
The flexural properties of wood–plastic composite (WPC) deck boards exposed to 9.5 years of environmental decay in Hilo, Hawaii, were compared to samples exposed to moisture and decay fungi for 12 weeks in the laboratory, to establish a correlation between sample flexural properties and calculated void volume. Specimens were tested for flexural strength and modulus, both wet and dry, at 23°C and 52°C. Some specimens degenerated to only 15% of original flexural strength. UV radiation had no impact on flexural properties of field-exposed boards; loss occurred mainly on the side opposite to the sun-exposed surface. The mechanism of the aging process on colonization of WPC by fungi was examined and is consistent with development of slow crack growth in the polyethylene matrix combined with wood decay by fungi. Wood particle decay, moisture, and elevated temperature were the major factors causing composite degradation, indicated by accumulation of voids and a severe decrease in flexural properties. To simulate long-term field impact (including decay) on WPC flexural properties in the laboratory, conditioning of specimens in hot water for an extended period of time is required. Exposure to water (70°C/5 days) was adequate for simulating long-term composite exposure in Hawaii of 4?×?15?×?86 mm3 specimens. 相似文献