Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2017
Authors
Dionisio Andújar Xavier Rodriguez Victor Rueda-Ayala Carolina San Martín Angela Ribeiro César Fernández-Quintanilla José DoradoAbstract
New technologies, such as Differential Global Positioning Systems (DGPS) and Geographic Information Systems (GIS), may be useful in order to create models to predict the spatio-temporal behaviour of weeds. The aim of this study was to generate a geometric model able to predict the patch expansion of S. halepense, a problematic perennial weed in maize crops in Central Spain. From previous infestation maps, the model describes new possible spreading areas for the upcoming growing season, and therefore, herbicide treatments can be planned on time. Two different experiments were implemented, in which initial patch density and size were examined. Patches of different size (1, 10 and 100 m2) and density (4, 20 and 100 shoots m−2), were established. These patches were visually identified, their perimeter defined and their density characterized, during three growing seasons (from 2008 to 2010 campaigns). According to this information different descriptors were built: (1) area and density of each patch; (2) the relative growth in width and length, according to space and time and compared with previous years; and (3) the increased density ratio, calculated in relation of patch size and distance to previous patch in the new infestation areas of expansion. All these descriptors were added to the model in order to predict the patch expansion in the last studied season (i. e., 2010) using previous maps (i. e., season 2008 and 2009). The model uses geometrical assimilation to predict, and two expansion assumptions were considered: (a) a conservative approach based on triangular geometry; and (b) a rectangular geometry which maximizes the simulated infested area. The results were compared with the ground truth map created in 2010. Each method showed weaknesses and strengths. The triangular approach minimized the infested area, mainly in the small patches, and therefore it could predict the expansion of previously established patches, but not the emergence of new ones. In contrast, the rectangular approach simulated the position of new foci, maximizing the infested area. Therefore, although a substantial reduction of herbicides is possible using both models, a final decision must be taken individually for each field.
Abstract
Mapping and valuating ecosystem services has gained increasing attention over the last years and remains high in the research agenda. In this paper, a mixed methods approach is used to valuate ecosystem services provided by the Divici-Pojejena wetland in Romania. A qualitative part relied on focus group discussions and interviews to identify key stakeholders and the ecosystem services provided by the wetland site. The benefit transfer (BT) method was used for the monetary valuation of the identified ecosystem services that the wetland provides. Bird watching opportunities, water quality, and flood prevention services are among the highest valued services, while the amenity services are the least valued among all wetland services.
Authors
Anna Palmé Heli Fitzgerald Jens Weibull Åsmund Asdal Birgitte Lund Dag Terje Filip Endresen Elina Kiviharju Hjörtur Þorbjörnsson Morten Rasmussen Ulrika Carlson-NilssonAbstract
The Nordic project “Ecosystem services: Genetic resources and crop wild relatives” was initiated with the long-term aim to assure conservation and sustainable use of the wild genetic resources associated with future food security. There is an increasing threat to crop wild relatives (CWRs) in nature and actions are therefore needed to safeguard these important resources. The Nordic project has resulted in two stakeholder workshops (Stockholm 2015, Vilnius 2016), a common homepage dedicated to Nordic CWR (www.nordgen.org/cwr), policy recommendations on CWR conservation and use and the first common Nordic conservation approach for CWRs. During the project, a common CWR checklist was created and prioritized. The most important crop wild relatives of the region, related to food and forage crops, were selected with use and value criteria. The in situ conservation planning identified potential complementary conservation sites for the priority species. These sites would conserve a maximum number of target taxa and their intraspecific variation by using ecogeographic land characteristic map categories of the region as a proxy for the adaptive scenarios of the priority taxa populations. The potential conservation sites are found in all the five countries (Denmark, Iceland, Finland, Norway and Sweden) across the Nordic region. Since the Nordic countries share many species and habitats across the region, the goal is that joint conservation planning on the Nordic level should make national conservation activities more efficient. The project is funded by Nordic Council of Ministers.
Abstract
No abstract has been registered
Authors
Mihaela-Olivia Dobrica Catalin Lazar Lisa Paruch Hanne Skomedal Hege Særvold Steen Sissel Haugslien Catalin Tucureanu Iuliana Caras Adrian Onu Sonya Ciulean Alexandru Branzan Jihong Liu Clarke Crina Stavaru Norica Branza-NichitaAbstract
Chronic Hepatitis B Virus (HBV) infection leads to severe liver pathogenesis associated with significant morbidity and mortality. As no curable medication is yet available, vaccination remains the most costeffective approach to limit HBV spreading and control the infection. Although safe and efficient, the standard vaccine based on production of the small (S) envelope protein in yeast fails to elicit an effective immune response in about 10% of vaccinated individuals, which are at risk of infection. One strategy to address this issue is the development of more immunogenic antigens. Here we describe a novel HBV antigen obtained by combining relevant immunogenic determinants of S and large (L) envelope proteins. Our approach was based on the insertion of residues 21-47 of the preS1 domain of the L protein (nomenclature according to genotype D), involved in virus attachment to hepatocytes, within the external antigenic loop of S. The resulting S/preS121-47 chimera was successfully produced in HEK293T and Nicotiana benthamiana plants, as a more economical recombinant protein production platform. Comparative biochemical, functional and electron microscopy analysis indicated assembly of the novel antigen into subviral particles in mammalian and plant cells. Importantly, these particles preserve both S- and preS1-specific epitopes and elicit significantly stronger humoral and cellular immune responses than the S protein, in both expression systems used. Our data promote this antigen as a promising vaccine candidate to overcome poor responsiveness to the conventional, S protein-based, HBV vaccine.
Authors
Shuxin Han Yanling Gao Guoquan Fan Wei Zhang Cailing Qiu Shu Zhang Yanju Bai Junhua Zhang Carl Jonas Jorge SpetzAbstract
This study reports the findings of a distinct Potato virus Y (PVY) isolate found in Northeast China. One hundred and ten samples (leaves and tubers) were collected from potato plants showing mosaic symptoms around the city of Harbin in Heilongjiang province of China. The collected tubers were planted and let to grow in a greenhouse. New potato plants generated from these tubers showed similar symptoms, except for one plant. Subsequent serological analyses revealed PVY as the causing agent of the disease. A novel PVY isolate (referred to as HLJ-C-44 in this study) was isolated from this sample showing unique mild mosaic and crisped leaf margin symptoms. The complete genome of this isolate was analyzed and determined. The results showed that HLJ-C-44 is a typical PVY isolate. Phylogenetic analysis indicated that this isolate belongs to the N-Wi strain group of PVY recombinants (PVYN-Wi) and also shared the highest overall sequence identity (nucleotide and amino acid) with other members of this strain group. However, recombination analysis of isolate HLJ-C-44 revealed a recombination pattern that differed from that of other PVYN-Wi isolates. Moreover, biological assays in four different potato cultivars and in Nicotiana tabacum also revealed a different phenotypic response than that of a typical PVYN-Wi isolate. This data, combined, suggest that HLJ-C-44 is a novel PVY recombinant with distinct biological properties.
Abstract
No abstract has been registered
Abstract
The extractive content of inner and outer heartwood of nine Scots pine trees from three different stands in Norway was determined by automated solvent extraction and biological screening tests were performed using basidiomycetes. The evaluation of mass spectra by means of a NIST library search shows that in the petroleum ether extracts α-pinene and carene as well as terpinene and cadinene derivatives are the main extractives found in both inner and outer heartwood. In the inner heartwood, however, these substance groups were found in lower quantities. These substances mainly have a hydrophobic effect. The screening tests indicate that also extractive-rich heartwood is extremely degraded by Poria placenta which corresponds to the analytical results of the petroleum ether extracts.
Abstract
No abstract has been registered
Academic – A study of variance estimation methods for systematic spatial sampling
Geir-Harald Strand
Authors
Geir-Harald StrandAbstract
An undesirable property of systematic spatial sampling is that there is no known method allowing unbiased estimation of the uncertainty of statistical estimates from these surveys. A number of alternative variance estimation methods have been tested and reported by various authors. Studies comparing these estimators are inconclusive, partly because the studies compare different sets of estimators. In this paper, three estimators recommended in recent studies are compared using a single test dataset with known properties. The first estimator compared in this study (ST4) is based on post-stratification of the data. The second estimator (V08) is using a predetermined correction factor calculated from the spatial autocorrelation. The third estimator (MB) is a model based prediction calculated using values from the semivariogram. MB and ST4 were both found to be fairly accurate, while V08 consistently underestimated the variance in this study. V08 relies on the assumption that the autocorrelation structure in the dataset can be described using a particular exponential function. The most likely explanation of the weak result for V08 is that this assumption is violated by the empirical data used in the experiment. A better correction factor can be calculated, but the safe approach is to use MB or ST4.