Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2009
Forfattere
Margarita Novoa Garrido T.M. Steinum C.L. Marolda M. A. Valvano H. SørumSammendrag
Organic acids are being used in animal husbandry due to their positive effects on overall health and growth rate in animal husbandry. However, little is known about the long-term effects of organic acids on the normal microbiota. In this work, an Escherichia coli strain isolated from a healthy pig was passed weekly for 20 months in medium with and without formic acid (FA) to investigate the effects of long-term exposure to organic acids. Passages were made using buffered medium at pH 5.25 and 6.1 with and without FA. Colonies showing reduced O antigen lipopolysaccharide production and increased susceptibility to FA were isolated after 12 months exposure to FA at pH 5.25 and after 20 months exposure to FA at pH 6.1. Adaptation to acid and bacterial growth was strongly affected by FA at pH 5.25. Also, after 2 months of serial passages, we observed colonies exhibiting multicellular behaviour, with production of fimbriae and an extracellular matrix. We conclude that long-term exposure to FA of an E. coli isolate from the normal intestinal microbiota is associated with various changes in the bacterial cell surface involving reduced O antigen expression and increased extracellular matrix production together with increased susceptibility to FA.
Sammendrag
Crown rot caused by Phytophthora cactorum is an important disease in commercial strawberry production worldwide. The level of resistance varies greatly between cultivars, and many of the most commonly grown cultivars are quite susceptible to P. cactorum. Adequate soil drainage, clean planting material and use of highly resistant cultivars are the most important measures against crown rot. Previous work at our institute has involved evaluation of methods to screen for resistance, cultivar and progeny screening, and use of induced resistance against the disease. That work also included a genetic study of P. cactorum isolates from various host plants and different geographic origins. P. cactorum has many host plants, but it turned out that isolates causing crown rot of strawberry differs genetically from those with other host origin. A project was recently initiated, where one of the main goals has been to identify molecular markers for resistance against P. cactorum in strawberry. Genotypes of diploid Fragaria species have been screened for resistance, and the progeny from a cross between a susceptible and a resistant genotype will be evaluated by the end of this year. Commercially grown strawberry is very heterozygous and octoploid. Diploid Fragaria species are therefore useful as model organisms. The Fragaria genus has a conserved organisation, and hopefully information obtained from the study of diploid genotypes can be transferred to cultivated Fragaria x ananassa and possibly to other important crop plants in Rosaceae.
Forfattere
Jørgen Lassen Ivar Dugstad Wijnand Eduard Gro Johannesen Lars NesheimSammendrag
I brev av 10.02.2009 til VKM ba Mattilsynet om en vurdering av helsefaren ved spredning av gylle under norske forhold med særlig vekt på mulig spredning av Salmonella, Cryptosporidium, Campylobacter, Escherichia coli og Yersinia enterocolitica, enten direkte til mennesker eller indirekte ved spredning via vann, planter og husdyr. Bakgrunnen for henvendelsen er at Danmark fra 2001, på grunnlag av en risikovurdering hvor Salmonella og Cryptosporidium ble brukt som modeller, har innført forbud mot spredning av fortynnet gylle med vanningskanoner med begrunnelsen at metoden er "forbundet med sunnhetsmessige risikoer for folk som oppholder seg i, eller ferdes i nærheten av, områdene som gjødsles". Det anslås at det i Norge årlig produseres 6,8 millioner tonn storfegjødsel og 3,7 millioner tonn grisegjødsel. Om lag halvparten av jordbruksarealet ved enheter med husdyr gjødsles minst én gang årlig, 75 % av gjødsla spres som "bløtgjødsel" (gylle) på eng og beite, ca. 2/3 spres om våren. Mikrobene som befinner seg i gylle vil stort sett stamme fra dyrenes tarmflora. De vil derfor kunne være tarmpatogene, men vanligvis ikke luftveispatogene. Et mulig unntak kan likevel være Legionella - dersom de finnes i gylle. Men det er foreløpig ukjent. Av aktuelle zoonotiske agens er forekomsten av Salmonella svært lav i norske husdyrbesetninger. Campylobacter og verotoksinprodusernde E. coli (VTEC) forekommer derimot sannsynligvis regelmessig i norske storfebesetninger. Hva angår serotypene av EHEC (den humanpatogene gruppen av VTEC) som oftest er assosiert med sykdom hos menneske (O26, O103, O111, O145 og O157), er forekomsten hos dyr lav. Man kan allikevel aldri utelukke at humanpatogene EHEC-stammer er tilstede i avføring fra drøvtyggere. Gris er hovedreservoar for Yersinia enterocolitica . Også parasittene Cryptosporidium og Giardia forekommer regelmessig både i storfe- og grisebesetninger i Norge. Man må derfor anta at gylle her i landet, basert på storfe- og griseavføring, kan være en potensiell spreder av EHEC, Campylobacter, Yersinia enterocolitica og begge de nevnte parasittene, mens spredning av Salmonella er mindre sannsynlig.
Forfattere
Carl Einar Amundsen Thomas HartnikSammendrag
Perfluorinated organic compounds (PFCs) have been emitted to the environment through the use of aqueous film forming foams (AFFF) at fire training facilities at airports and oil refineries in Norway since the 1960s. Since 3M decided to phase out the production based upon 1-perfluorooctane sulphonylfluoride (POSF) in year 2000, more foams are based upon fluorotelomer AFFFs products. To consider how the terrestrial and aquatic environments at previous and active training facilities have been affected by fluorine-containing foam the last decades, the occurrence of 19 PFCs were determined in samples of soil, sediments, biota and water collected at four selected fire training facilities in Norway in 2008. Concentrations of perfluoroctylsulfonate (PFOS) in most soil samples (range 29-11923 ng/g) exceed the proposed Norwegian guideline value for PFOS in soil (100 ng/g). Laboratory bioaccumulation experiments using polluted field soils resulted in mean bioaccumulation factors (BAFs, n=12) for 6:2 fluortelomersulfonate (6:2 FTS), PFOS and perfluoroctylcarboxylate (PFOA) of 2.4 (0.76-6.7), 2.6 (0.49-6.4) and 5.9 (0.31-14.0), respectively. For perfluorinated sulfonates (PFS) and perfluorinated carboxylates (PFCA), BAF increased with increasing chain length. The PFOS precursor N-Et-FOSA had BAFs for earthworms in the range 188-770, and mean BAF of C9-C14 PFCAs in the range 10-100. Analysis of samples from soil profiles (0-80cm) show that PFCs with long carbon chains (C9-C14) are less mobile than PFCs with shorter chain lengths (C4-C8). Due to leaching in the soil profile, high concentrations of PFCs have been found in groundwater at one of the sites. High concentrations of PFCs in marine biota, sediments, surface water and groundwater in the vicinity of the training facilities, relatively high mobility in soils, and high bioaccumulation potential of some PFCs, make PFCs a potential environment threat at fire training and testing sites that should be additionally assessed.
Forfattere
Anne-Kristin Løes Benjamin NöltingSammendrag
The work in, and deliverables so far from the iPOPY project have demonstrated that each country has its own history and cultural background, explaining the huge differences in current school meal systems and use of organic products. Each country has its own path of development in this respect; however, it is beyond doubt that school meal systems will change with time everywhere due to the pressing health and environmental problems as well as changes in the education structure (longer school days). These changes provide the opportunity to introduce the ideas of organic food - expressed e. g. by the four basic principles of organic agriculture: health, ecology, fairness, and care from IFOAM - into public food procurement for children and youth. However, these ideas are not static and fix, they need to be evolved in and adapted to the specific and complex context of POPY. There is much to learn from the four countries both with respect to challenges and problems, and with respect to good ideas and creative solutions. By our transnational research and activities, iPOPY contributes to carry this knowledge across boundaries. We consider this work to be a small, but very meaningful contribution to point out public procurement strategies for sustainable nutrition which can foster a more sustainable world for all.
Forfattere
Csilla FarkasSammendrag
The latest climate change scenarios, forecasting for the Tisza watershed valuable increase in the occurrence of extreme weather events as well as changes in land use policy increased the demand on knowledge towards sustainable flood plain and water reservoir management. The main objective of the present study was to develop an appropriate methodology that could be used for describing the soil water regime of the Bodrog Interfluve floodplain area at sub-regional scale and to derive the corresponding soil and hydrological database. This paper describes the fine-scale spatial soil database, constructed for characterizing the soil cover of the Hungarian territory of the Bodrog Region; the monitoring system, established in the study area and the mathematical modeling procedure carried out for better description of soil water regime and water balance elements. Further, performance and results of a scenario analyses are presented for evaluating the possible effects of two recently predicted climate change scenarios on soil water regime of a sensitive floodplain area. It was concluded, that based on the adaptation of a water balance simulation model and on the spatial soil physical database, the water regime of the dominant natural, semi-natural and agrarian ecosystems could be estimated. Compared to the present circumstances, the results of the scenarios analyses indicated more uneven and extreme surface and subsurface hydrological situations under changing climatic conditions.
Forfattere
Robert C. Seem Arne Stensvand David M. Gadoury Håvard Eikemo Andrew Dobson M. Catherine HeidenreichSammendrag
The objective of this work was to investigate how primary disease levels of powdery mildew (Podosphaera aphanis) in strawberry (Fragaria × ananassa) influence disease development in time and space. Experiments were repeated over two seasons in field trials in Norway (Ås, cv. Korona) and USA (Geneva, NewYork, cvs. Earliglow and Elan). Five-row plots of 50 to 100 mildew-free plants (planting distance 0.45 x 1.2 m) were established each year within large grain fields, with a minimum distance of 90 m between plots, and no fungicide treatments. At start of the experiments, plants at the center of each plot were inoculated with 0, 1, 10, or 100 mildew-infected leaflets. Uninoculated plots developed only trace levels of powdery mildew, despite nearby diseased plots. More rapid and severe disease development was observed in the inoculated plots; e.g., mildew was observed on 31, 36, 311, and 912 leaflets in the 0, 1, 10, and 100 plots, respectively, in Norway in year 1 of the trial. Within the plots, disease development was highest close to the inoculum source and downwind from the prevailing wind. It may be concluded that in the absence of nearby sources of contamination, disease severity in strawberry plantings is determined by the dose of initial inoculum resident within the planting. The practical impact of the trials was to demonstrate long-lasting benefits of clean, mildew-free planting stock in commercial strawberry production, even in areas where the pathogen is endemic and the environment is very conducive to disease.
Forfattere
Adam ParuchSammendrag
Laboratory scale experiment on survival of Escherichia coli (E. coli) in samples of filter media used in constructed wetlands (CWs) treating domestic wastewater was performed. Concentration of E. coli was examined in 42 samples collected from a wetland filter/bed. All samples positive for E. coli contamination were used to assess the effect of storage time at different temperature regimes on the survival of E. coli. Storage time was set up as an unlimited factor, while temperature conditions were limited by three regimes, 4, 10 and 22 degrees. It was found that E. coli had higher persistence in samples collected from the upper, subsurface level comparing to samples taken from deeper levels (35 - 50 cm and 65 - 80 cm). Survival of E. coli in filter media collected below the depth of 35 cm from the surface level of CWs was counted up to 21 days. It was observed, however, that E. coli could survive for 14 months in samples of filter media collected right below the organic layer (5 cm). Concentration of E. coli in these samples, stored at 10 degrees, increased radically during the first 6 months and then rapidly decreased during next 1,5 month of storage. Thereafter, a slow decrease of E. coli numbers was registered up to the level that no E. coli was detected. The highest survival rate was observed in samples stored at 10 degrees, but the longest period of survival was noticed in samples stored at 4 degrees.
Forfattere
Jahn Davik Elena Lopez Girona Daniel J Sargent Monica C Muñoz-Torres Amparo Monfort Julio Bonet Albert G Abbott Pere Arús David W SimpsonSammendrag
BackgroundThe cultivated strawberry Fragaria ×ananassa is one of the most economically-important soft-fruit species. Few structural genomic resources have been reported for Fragaria and there exists an urgent need for the development of physical mapping resources for the genus. The first stage in the development of a physical map for Fragaria is the construction and characterisation of a high molecular weight bacterial artificial chromosome (BAC) library.MethodsA BAC library, consisting of 18,432 clones was constructed from Fragaria vesca f. semperflorens accession "Ali Baba". BAC DNA from individual library clones was pooled to create a PCR-based screening assay for the library, whereby individual clones could be identified with just 34 PCR reactions. These pools were used to screen the BAC library and anchor individual clones to the diploid Fragaria reference map (FV×FN).FindingsClones from the BAC library developed contained an average insert size of 85 kb, representing over seven genome equivalents. The pools and superpools developed were used to identify a set of BAC clones containing 70 molecular markers previously mapped to the diploid Fragaria FV×FN reference map. The number of positive colonies identified for each marker suggests the library represents between 4× and 10× coverage of the diploid Fragaria genome, which is in accordance with the estimate of library coverage based on average insert size.ConclusionThis BAC library will be used for the construction of a physical map for F. vesca and the superpools will permit physical anchoring of molecular markers using PCR.
Sammendrag
Members of the APSES family of fungal proteins have been identified as key regulators of fungal development, controlling processes such as mating, sporulation and dimorphic growth. We deleted the FgStuA gene in Fusarium graminearum and show that the mutant is greatly impaired in spore development, pathogenicity and secondary metabolism. FgStuA is closely related to FoStuA in F. oxysporum, but unlike FoStuA mutants the FgStuA mutants were greatly reduced in pathogenicity both on wheat and apple slices. The lack of ability to cause disease on wheat heads may be due to lack of trichothecene accumulation in planta. The FgStuA mutant also had a white/yellow mycelial phenotype compared to the red pigmented (aurofusarin) wild-type, had reduced aerial mycelium, susceptibility to oxidative stress, and had a less hydrophobic surface. Microarray analysis showed that most phenotypes could be inferred from gene expression data, such as down-regulation of the trichothecene gene cluster in the mutant. In an attempt to separate primary and secondary effects of FgStuA deletion, we carefully examined gene expression data together with promoter analysis and comparative genomics. The genes flanking FgStuA are conserved and syntenous in other fungal genomes and contain a gene encoding a putative clock controlled protein. FgStuAp and other APSES proteins share significant homology with DNA-binding domains of transcription factors controlling the critical G1/S phase cell cycle transition in both S. cerevisiae and S. pombe. Genes within MIPS Functional Category (FunCat) 10 "Cell cycle and DNA processing" are enriched among those more highly expressed in the FgStuA mutant than wild-type. Aspergillus StuAp response elements (A/TCGCGT/ANA/C) also were found highly enriched in promoter sequences for FunCat 10 genes, compared to the genome as a whole. Our results suggests that FgStuAp may act primarily as a repressor involved in cell cycle regulation, and may act only secondarily on sporulation, pathogenicity, and secondary metabolism.