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排序方式: 共有65条查询结果,搜索用时 46 毫秒
1.
Maria Holmberg Anu Akujärvi Saku Anttila Lauri Arvola Irina Bergström Kristin Böttcher Xiaoming Feng Martin Forsius Inese Huttunen Markus Huttunen Yki Laine Heikki Lehtonen Jari Liski Laura Mononen Katri Rankinen Anna Repo Vanamo Piirainen Pekka Vanhala Petteri Vihervaara 《Landscape Ecology》2015,30(3):561-577
2.
Minna-Liisa?RantalainenEmail author Hannu?Fritze Jari?Haimi Oili?Kiikkil? Taina?Pennanen Heikki?Set?l? 《Biology and Fertility of Soils》2004,39(3):200-208
Due to their high abundance and ubiquitous existence, microbes are considered to be efficient colonisers of newly established habitats. To shed light on the dispersal mechanisms of soil microbes, a controlled microcosm experiment was established. In these microcosms, the dispersal of microbes from a source humus patch to originally sterile humus patches (embedded in a mineral soil matrix) was followed for 16 months, applying 16S and 18S ribosomal DNA-based PCR-DGGE molecular methods. Specifically, the role of enchytraeid worms and habitat (humus) corridors as possible facilitators of microbe dispersal was studied. The results showed that enchytraeid worms function efficiently as vectors for horizontal dispersal of saprophytic fungi in soil. Some of the fungi also proved to disperse through the corridors by vegetative growth, although this dispersal was inefficient as compared to dispersal with the enchytraeids. Virtually no saprophytic fungi were able to disperse through the mineral soil matrix in the absence of both enchytraeid worms and corridors. Unlike soil fungi, the dispersal of soil bacteria was not affected by any of the studied factors. The results of the present experiment provide direct evidence of the crucial role of soil fauna in aiding the horizontal dispersal of soil fungi. The role of enchytraeids as a functionally important species in boreal forest soils is further emphasized, since bringing microbes into contact with new resources is likely to enhance the rate of decomposition in soils. 相似文献
3.
Tiina Korkama Hannu Fritze Oili Kiikkilä Taina Pennanen 《Soil biology & biochemistry》2007,39(9):2420-2423
The influence of individual trees in monocrop forests on soil microbial communities is poorly understood. We measured basal respiration, substrate-induced respiration and phospholipid fatty acids (PLFA), bacterial growth rate with the 3H-thymidine incorporation technique and fungal growth rate as 14C-acetate incorporation into ergosterol to investigate whether slow- and fast-growing 12-year-old Norway spruce (Picea abies) clones have affected differently on their associated soil microbial communities. Understorey vegetation, soil chemical properties and elemental concentrations of needles were also determined. The slow- and fast-growing spruce clones differed in PLFA profiles, understorey vegetation and elemental concentrations in needles suggesting that spruce clones have directly or indirectly affected soil microbes. 相似文献
4.
Rajamäki MM Järvinen AK Sorsa TA Tervahartiala TI Maisi PS 《Veterinary journal (London, England : 1997)》2006,171(3):562-565
Inflammation causes epithelial cell sloughing and basement membrane (BM) exposure in canine pulmonary eosinophilia (PE), leading to degradation of the epithelial cell attachment component, laminin-5 gamma2-chain, into small molecular weight fragments. The subsidence of inflammation after treatment down-regulates degradation. Laminin-5 gamma2-chain levels and molecular forms in bronchoalveolar lavage fluid (BALF) were analysed semiquantitatively by Western immunoblotting to compare PE affected (n=20) and healthy dogs (n=16) as well as PE dogs (n=6) before and after corticosteroid treatment. PE dogs expressed significantly elevated levels of total (P<0.01), 36 kDa (P<0.05) and 53 kDa (P<0.05) laminin-5 gamma2-fragments. The 36 Da fragment decreased significantly (P<0.05) after treatment. The laminin-5 gamma2-chain degradation products may be linked to epithelial cell sloughing and BM exposure or healing. 相似文献
5.
Tiina Nokireki Taina Laine Laura London Niina Ikonen Anita Huovilainen 《Acta veterinaria Scandinavica》2013,55(1):69
Background
Swine influenza is an infectious acute respiratory disease of pigs caused by influenza A virus. We investigated the time of entry of swine influenza into the Finnish pig population. We also describe the molecular detection of two types of influenza A (H1N1) viruses in porcine samples submitted in 2009 and 2010.This retrospective study was based on three categories of samples: blood samples collected for disease monitoring from pigs at major slaughterhouses from 2007 to 2009; blood samples from pigs in farms with a special health status taken in 2008 and 2009; and diagnostic blood samples from pigs in farms with clinical signs of respiratory disease in 2008 and 2009. The blood samples were tested for influenza A antibodies with an antibody ELISA. Positive samples were further analyzed for H1N1, H3N2, and H1N2 antibodies with a hemagglutination inhibition test. Diagnostic samples for virus detection were subjected to influenza A M-gene-specific real-time RT-PCR and to pandemic influenza A H1N1-specific real-time RT-PCR. Positive samples were further analyzed with RT-PCRs designed for this purpose, and the PCR products were sequenced and sequences analyzed phylogenetically.Results
In the blood samples from pigs in special health class farms producing replacement animals and in diagnostic blood samples, the first serologically positive samples originated from the period July–August 2008. In samples collected for disease monitoring, < 0.1%, 0% and 16% were positive for antibodies against influenza A H1N1 in the HI test in 2007, 2008, and 2009, respectively. Swine influenza A virus of avian-like H1N1 was first detected in diagnostic samples in February 2009. In 2009 and 2010, the avian-like H1N1 virus was detected on 12 and two farms, respectively. The pandemic H1N1 virus (A(H1N1)pdm09) was detected on one pig farm in 2009 and on two farms in 2010.Conclusions
Based on our study, swine influenza of avian-like H1N1 virus was introduced into the Finnish pig population in 2008 and A(H1N1)pdm09 virus in 2009. The source of avian-like H1N1 infection could not be determined. Cases of pandemic H1N1 in pigs coincided with the period when the A(H1N1)pdm09 virus was spread in humans in Finland. 相似文献6.
Gosset V Göbel C Laine G Delaplace P du Jardin P Feussner I Fauconnier ML 《Journal of agricultural and food chemistry》2008,56(23):11285-11292
The impact of processing on nonenzymatic antioxidant degradation and lipid oxidation leading to off-flavor development in potato flakes during storage was investigated. Lipoxygenase activity measurements in parallel with the analysis of lipid oxidation products (oxylipins) profiles using HPLC showed that the processing conditions used inhibited efficiently enzymatic lipid oxidation. However, nonenzymatic lipid oxidation products were found throughout processing and in fresh potato flakes. Furthermore, these autoxidative processes cannot be inactivated by the main endogenous nonenzymatic antioxidants in potato tubers (ascorbic acid, phenolic compounds and carotenoids), as these antioxidants are degraded during processing. Indeed, leaching and thermal treatments taking place during processing lead to a decrease of about 95%, 82% and 27% in the content of ascorbic acid, phenolic compounds and carotenoids, respectively. Therefore, storage is a critical step to prevent off-flavor development in potato flakes. Specific attention has thus to be paid on the use of efficient exogenous antioxidants as well as on storage conditions. 相似文献
7.
Päivi Mäkiranta Kari Minkkinen Jyrki Hytönen Jukka Laine 《Soil biology & biochemistry》2008,40(7):1592-1600
Partitioning soil respiration (SR) into its components, heterotrophic and rhizospheric respiration, is an important step for understanding and modelling carbon (C) cycling in organic soils. However, no partitioning studies on afforested organic soil croplands exist. We separated soil respiration originating from the decomposition of peat (SRP), and aboveground litter (SRL) and root respiration (SRR) in six afforested organic soil croplands in Finland with varying tree species and stand ages using the trenching method. Across the sites temporal variation in SR was primarily related to changes in soil surface temperature (?5 cm), which explained 71–96% of variation in SR rates. Decomposition of peat and litter was not related to changes in water table level, whereas a minor increase in root respiration was observed with the increase in water table depth. Temperature sensitivity of SR varied between the different respiration components: SRP was less sensitive to changes in soil surface temperature than SRL or SRR. Factors explaining spatial variation in SR differed between different respiration components. Annual SRP correlated positively with peat ash content while that of SRL was found to correlate positively with the amount of litter on the forest floor, separately for each tree species. Root respiration correlated positively with the biomass of ground vegetation. From the total soil respiration peat decomposition comprised a major share of 42%; the proportion of autotrophic respiration being 41% and aboveground litter 17%. Afforestation lowered peat decomposition rates. Nevertheless the effect of agricultural history can be seen in peat properties for decades and due to high peat decomposition rates these soils still loose carbon to the atmosphere. 相似文献
8.
Minna-Liisa Rantalainen Jari Haimi Hannu Fritze Taina Pennanen Heikki Setälä 《Soil biology & biochemistry》2008,40(4):853-863
Due to the practical difficulties of experimental study of habitat fragmentation and habitat corridors at the landscape scale, the use of smaller-scale model systems has been offered as a feasible alternative to uncover the ecological phenomena taking place in fragmented environments. In this mini-review, we consider the applicability of the soil decomposer community as such a model system. For the most part, this article is based on the few studies that have explicitly addressed this question by experimental manipulations of the natural habitat of soil decomposer community. However, to broaden the view, we also capitalize upon studies focusing on the effects of isolation and soil use changes on soil organisms and on dispersal of soil fauna, all of these being considered as factors determining the sensitivity of organisms to habitat fragmentation. Since usability of a model system by definition depends on the possibility of applying the results to other (usually larger scale) systems, we discuss the characteristics of the soil decomposer community also from this point of view.The existing data suggest that soil organisms, in general, are not sensitive to habitat fragmentation even in small scale. Because of this, and the unique features of the belowground environment and its biota combined with gaps in the knowledge of the life history characteristics of soil organisms, the soil decomposer community is not ideal for predicting the implications of habitat fragmentation and habitat corridors on threatened species. Despite this, we still believe that there are lessons to be learned by studying the effects of habitat fragmentation on this important community of organisms, especially in combination with the consequences of ongoing climate change. 相似文献
9.
Taina M Laine Tapani Lyytik?inen Maija Yliaho Marjukka Anttila 《Acta veterinaria Scandinavica》2008,50(1):21
Background
Post-weaning diarrhoea (PWD) is a significant gastrointestinal disease in pigs. It is considered a multifactorial disease associated with proliferation of enterotoxigenic Escherichia coli in the intestinal tract of affected pigs. The aim of this study was to analyse risk factors related to the occurrence of PWD on Finnish piglet producing farms.Methods
The data of a follow-up study of 73 conventional piglet producing farms was used in the case-control study. The selection of the 41 PWD case and 28 control farms was based on the use of antimicrobials for treating diarrhoea in weaned pigs and the answers related to the occurrence of diarrhoea after weaning in the questionnaire. Four intermediate farms were excluded from the statistical analysis.Altogether 39 factors related to herd characteristics, weaner pig management and pig health were studied. The median number of sows was 59.0 (IQR = 44.0; 74.5) and 52.5 (IQR = 36.8; 61.5) on the case and the control farms, respectively.The significances of the univariable associations between the explanatory variables and the outcome variable were tested, and in the multivariate analysis quasibinomial generalized linear models were applied.Results
An increased risk of PWD was associated with the regimen of twice a day feeding and feed restriction after weaning (P = 0.02; compared to feeding three or more meals a day or the use of ad libitum feeding) and with a higher number of sows on the farm (P = 0.02; risk increasing with increasing number of sows). Automatic temperature control was associated with a decreased risk of PWD (P = 0.03; compared to manual temperature control).Conclusion
Twice a day feeding of newly-weaned pigs should be avoided if the amount of feed given is restricted. Variation in ambient temperature should be minimized in housing of newly-weaned pigs and this can be achieved by using automatic temperature control. With increasing number of sows in the herds the risk of PWD increases and more attention should be paid to prevention of post-weaning diarrhoea. 相似文献10.
Ayco J. M. Tack Anna-Liisa Laine 《European journal of plant pathology / European Foundation for Plant Pathology》2014,138(3):667-677
In recent years the potential for evolutionary change to drive ecological dynamics, and vice versa, has been widely recognized. However, the convincing examples of eco-evolutionary dynamics mainly stem from highly artificial experimental systems, with conspicuously few examples contributed by field systems. While rarely considered in the eco-evolutionary literature, the gene-for-gene hypothesis inherently recognizes the tight link between evolutionary and ecological dynamics. The boom-and-bust dynamics of some agricultural pathogens are an extreme demonstration of this. In this perspective, we place plant-pathogen systems in a spatial eco-evolutionary framework, which recognizes that ecology and evolution are tightly linked, take place at the same time scale and are strongly influenced by spatial structure. Specifically, we: i) exemplify how the ecological process of dispersal modifies rapid local coevolutionary dynamics and thereby shapes spatial variation in resistance, infectivity, and local adaptation; and ii) illustrate how the outcome of coevolution (spatial distribution in resistance, infectivity and local adaptation) drives ecological metapopulation processes. Overall, we conclude that both agricultural and wild pathosystems provide a unique illustration of the high relevance of spatial eco-evolutionary feedback in understanding species interactions. 相似文献