Old soil carbon is more temperature sensitive than the young in an agricultural field     

Pekka Vanhala  Kristiina Karhu  Eloni Sonninen  Hannu Fritze 《Soil biology & biochemistry》2007,39(11):2967-2970

Changes in the carbon stock of soil in response to climate change would significantly affect the atmospheric carbon dioxide concentration and consequently climate. The isotopes of carbon provide a means to study the temperature sensitivities of different soil carbon fractions. Where C3 vegetation has changed for C4, soil organic matter (SOM) from the different origins have different ¹³C/¹²C ratios. Relying on this feature, we took soil samples from a control field and a field where ordinary grain (C3) vegetation was replaced by maize (C4), 5 years ago. We measured the respiration rate and the ¹³C/¹²C ratio of the CO₂ produced by the samples at different temperatures. Based on these measurements, we quantified that Q₁₀ was 3.4-3.6 for the total CO₂ production while it was 2.4-2.9 at 20 °C for the maize-derived young carbon and 3.6 for the older C3-derived carbon. Our results suggest that climatic warming will accelerate especially the decomposition of the large pool of old soil carbon in these fields.  相似文献   

Transfer of N fixed by a legume tree to the associated grass in a tropical silvopastoral system     

Jorge Sierra  Pekka Nygren 《Soil biology & biochemistry》2006,38(7):1893-1903

Below-ground transfer of nitrogen (N) fixed by legume trees to associated non-N₂-fixing crops has received little attention in agroforestry, although the importance of below-ground interactions is shown in other ecosystems. We used ¹⁵N natural abundance to estimate N transfer from the legume tree Gliricidia sepium (Jacq.) Kunth ex Walp. to C₄ grass Dichanthium aristatum (Poir.) C.E. Hubb. in a silvopastoral system, where N was recycled exclusively by below-ground processes and N₂ fixation by G. sepium was the sole N input to the system. Finding a suitable reference plant, a grass without contact with tree roots or litter, was problematic because tree roots invaded adjacent grass monocrop plots and soil isotopic signature in soil below distant grass monocrops differed significantly from the agroforestry plots. Thus, we used grass cultivated under greenhouse conditions in pots filled with agroforestry soil as the reference. A model of soil ¹⁵N fractionation during N mineralization was developed for testing the reliability of that estimate. Experimental and theoretical results indicated that 9 months after greenhouse transplanting, the percentage of fixed N in the grass decreased from 35% to <1%, due to N export in cut grass and dilution of fixed N with N taken up from the soil. The effect of soil ¹⁵N fractionation on the estimate of the reference value was negligible. This indicates that potted grass is a suitable reference N transfer studies using ¹⁵N natural abundance. About one third of N in field-grown grass was of atmospheric origin in agroforestry plots and in adjacent D. aristatum grassland invaded by G. sepium roots. The concentration of fixed N was correlated with fine root density of G. sepium but not with soil isotopic signature. This suggests a direct N transfer from trees to grass, e.g. via root exudates or common mycorrhizal networks.  相似文献   

A mercury model used for assessment of dredging impacts     

Titta Schultz  Pekka Korhonen  Markku Virtanen 《Water, air, and soil pollution》1995,80(1-4):1171-1180

The effects of dredging of contaminated sediments on the mercury (Hg) concentrations of prey and predatory fish were calculated for the Kokemäenjoki River and its estuary in Western Finland. The accumulation of Hg in fish is controlled by the Hg concentrations in water, zooplankton, zoobenthos and by suspended solids. Hg is accumulated into fish mainly through food web, eg. from perch (Perca fluviatilis) as prey and to pike (Esox lucius) as predator. In addition to dredging, temperature and flood situations have also increased the Hg accumulation and release from the bottom sediments. The validity of the model has been tested with data recorded from earlier dredgings. Thereafter the model has been used to predict the Hg levels caused by dredging planned upstream in the river. The predictions are supported by the concentrations of total mercury (Tot.Hg) and methyl mercury (MeHg) measured in water and in sediments under several flow conditions. As a result, 30 % increase of Hg in pike — from 0.8 to 1.05 mg/kg —was expected. This was too high, and therefore dredging was not included in the final plan for flood protection.  相似文献   

Effect of dinoseb on nitrogen fixation of red clover (Trifolium pratense)     

Kristina Lindström  Juhani Polkunen  Pekka Kansanen 《Soil biology & biochemistry》1985,17(6):865-869

The effect of the herbicide dinoseb (2-sec-butyl-4,6-dinitrophenol) on the symbiotic nitrogen fixation of red clover (Trifolium pratense cv. Venla) was studied in field, greenhouse and laboratory experiments. In the field, the herbicide reduced the levels of nitrogenase (C₂H₂) activity of the plants up to 18 days after treatment, but increased the yields compared to hand-weeded and unweeded controls. Rhizobium strains isolated from root nodules of plants treated with dinoseb showed resistance to the herbicide when grown on laboratory media containing dinoseb. However, in a pot experiment, inoculation with a strain which grew in the presence of 200 μg dinoseb ml^?1 did not improve the performance of red clover treated with dinoseb. In the pot experiment dinoseb inhibited nitrogenase activity when sprayed on the leaves, but not when added to the growth medium. Application of starter nitrogen did not influence the effect of dinoseb. The results suggest that dinoseb did not act directly on the nodules, but affected nitrogen fixation by damaging the photosynthetic parts of the plant.  相似文献   

Improving broad specificity hapten recognition with protein engineering   总被引：1，自引：0，他引：1  

Korpimäki T  Rosenberg J  Virtanen P  Karskela T  Lamminmäki U  Tuomola M  Vehniäinen M  Saviranta P 《Journal of agricultural and food chemistry》2002,50(15):4194-4201

Sulfa antibiotics (sulfonamides) are derivatives of p-aminobenzenesulfonamide that are widely used in veterinary medicine. Foods derived from treated animals may be contaminated with these drugs. However, current immunobased sulfonamide detection methods are unfit for screening of products because they are either too insensitive or specific for a few compounds only. An immunoassay capable of detecting all sulfas in a single reaction would be ideal for screening. For development of a binder capable of binding all sulfas, a protein engineering approach was chosen and the properties of monoclonal antibody 27G3 were improved with mutagenesis followed by selection with phage display. Several different mutant antibodies were isolated. The cross-reaction profile of the best mutant antibody was significantly improved over that of the wild-type antibody: it was capable of binding 9 of the tested 13 sulfonamides within a narrow concentration range and also bound the rest of the sulfas, albeit within a wider concentration range.  相似文献   

Using expert knowledge in combining green infrastructure and ecosystem services in land use planning: an insight into a new place-based methodology   总被引：1，自引：0，他引：1  

Leena Kopperoinen  Pekka Itkonen  Jari Niemelä 《Landscape Ecology》2014,29(8):1361-1375

Green infrastructure (GI) is a strategic planning instrument to achieve sustainable development. The main functions of GI are to protect biodiversity and safeguard and enhance the provision of ecosystem services (ES). In this paper we present the development of a semi-quantitative place-based method, aiming at assessing GI based on the provision potential of all main ES. Our method combines a wide spectrum of GIS data with expert assessments. Here we focus especially on how interaction with experts and local and regional actors impacted the method development. Our results showed that involving experts in dataset selection is very useful in compiling the most relevant data for the assessment of ES. Expert knowledge is also valuable in evaluating the actual coverage and quality of datasets. By involving both experts and local and regional actors in assessing ES provision potential we can add local knowledge to the general scientific understanding. Qualitative assessments can be complemented with quantitative data in our method. The resulting maps support land use planning, as they assist in identifying the multifunctional key areas of GI and in examining the provision potential of various ES. The group discussions involved in our method provided an additional benefit, as the experts and local and regional actors felt that this discussion platform enhanced their understanding of both GI and ES.  相似文献   

Derivatives of erythropoietin that are tissue protective but not erythropoietic   总被引：1，自引：0，他引：1  

Leist M  Ghezzi P  Grasso G  Bianchi R  Villa P  Fratelli M  Savino C  Bianchi M  Nielsen J  Gerwien J  Kallunki P  Larsen AK  Helboe L  Christensen S  Pedersen LO  Nielsen M  Torup L  Sager T  Sfacteria A  Erbayraktar S  Erbayraktar Z  Gokmen N  Yilmaz O  Cerami-Hand C  Xie QW  Coleman T  Cerami A  Brines M 《Science (New York, N.Y.)》2004,305(5681):239-242

Erythropoietin (EPO) is both hematopoietic and tissue protective, putatively through interaction with different receptors. We generated receptor subtype-selective ligands allowing the separation of EPO's bioactivities at the cellular level and in animals. Carbamylated EPO (CEPO) or certain EPO mutants did not bind to the classical EPO receptor (EPOR) and did not show any hematopoietic activity in human cell signaling assays or upon chronic dosing in different animal species. Nevertheless, CEPO and various nonhematopoietic mutants were cytoprotective in vitro and conferred neuroprotection against stroke, spinal cord compression, diabetic neuropathy, and experimental autoimmune encephalomyelitis at a potency and efficacy comparable to EPO.  相似文献   

Potential of dry fractionation of wheat bran for the development of food ingredients,part I: Influence of ultra-fine grinding   总被引：1，自引：0，他引：1  

Youna Hemery  Marc Chaurand  Ulla Holopainen  Anna-Maija Lampi  Pekka Lehtinen  Vieno Piironen  Abdelkrim Sadoudi  Xavier Rouau 《Journal of Cereal Science》2011

Wheat bran is an undervalued by-product of white flour and has great nutritional potential due to its high content in fibres and bioactive compounds. Micronized bran could be used as a food ingredient to improve the nutritional potential of cereal products, or be used as a starting material for other processes (bioactive compound extraction or bran fractionation). The aim of this work was to find a way to efficiently decrease the particle size of bran. The influence of the grinding temperature (ambient or cryogenic grinding) on the granulometric distribution of particles, their composition, and their microstructure was studied, at lab-scale and pilot-scale. It showed that the intrinsic characteristics of bran (glass transition within intermediate layers at −46 °C) had more influence on its grinding behaviour than the type of grinding device used: the particles size distributions obtained after grinding at lab-scale and pilot-scale were very similar. At both scales, the granulometric curves were narrow for cryogenic grinding, while for ambient grinding they were spread over the whole particle size range. Ultrafine particles were obtained in both ambient and cryogenic conditions. Negative temperatures, by increasing the material’s brittleness, favoured a fast fragmentation of bran: one step of cryogenic grinding allowed a median particle size of nearly 50 μm to be reached, whereas three successive steps of ambient grinding were needed for the same result. On the other hand, ambient temperature favoured the dissociation of the different constituent layers of wheat bran, and produced less composite particles than cryogenic grinding.  相似文献   

Effect of melatonin implant residuals in feed on reproduction in blue foxes     

Hannu Korhonen  Paavo Niemelä  Jaakko Mäkelä  Tuula Dahlman 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2013,63(4):261-263

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Biochemical Indicators of Suboptimal Protein Nutrition in Growing Horses during the First Indoor Season     

Pekka H. Mäenpää  Liisa Alakuijala  Erkki Koskinen 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2013,63(1):61-64

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