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 Cristina L. Marolda Miguel A. Valvano Henning SørumSammendrag
Et felles mål for medisinen og landbruket er å redusere bruk av antibiotika for på denne måten begrense utviklingen ab bakteriell antibiotika resistense. I landbruket vil dette bare kunne oppnås ved en forbedre dyrehelse. Bruk av organiske syrer (OS) som maursyre blandet i fôret eller vannet er en praksis som ar ganske utbredt i svin of fjørfe produksjonen. OS reduserer antall bakterier i tarmen og endrer balansen i tarmfloraen, noe som har vist å gi god smittekontroll og tilvekt. I Norden er det også vanlig å bruke maursyre for surfôr produksjonen på grunn av klimatiske forhold. Tarm bakterier har mekanismer for å overleve syreholdige forhold. På denne måten, en langsiktig bruk av OS kunne selektere for for stammer som uttrykker egenskaper som tillatter dem å overleve under syreholdige forhold. Økt syre toleranse-/resistense i bakterier ville øke smitte risiko. Etter å ha studert ulike egenskaper i et E. coli stamme under påvirkning av mild organisk surhet over tid har vi observert at tilstedetværelsen av OS i mediet er tilknyttet til endringer i O-antigen og cellulose-lignende karbohydrat. Vi konkluderer med at lang tidseksponering av E. coli overfor mild sur pH og små konsentrasjoner av OS svekker E. colis evne til å overleve magesekke barrieren.
Forfattere
Ricardo Holgado Kari Anne Oppen Christer MagnussonSammendrag
Soil samples from a growth depression in potato (Solanum tuberosum) cv. Saturna field in Grue, eastern Norway, yielded large numbers of root lesion nematodes, Pratylenchus penetrans. Yield of potato was reduced by 50% in the affected area of the field. Transect-sampling showed plant growth to be negatively correlated with densities of P. penetrans and suggested a damage threshold of potato to the nematode of 100 specimens per 250 g of soil. Common scab (Streptomyces scabies) occurred frequently in the affected area. Pratylenchus penetrans was present in roots, underground stems, stolons and tubers. In tubers, nematodes were detected inside cross-lesions typical of common scab, and occurred also in the outermost 0.5 mm tissue associated with such lesions. On potato cv. Saturna grown in a green-house, P. penetrans alone induced tuber lesions similar to those of common scab. Also, the combined inoculation of the bacterium and the nematode seemed to enhance symptom expression. Pratylenchus penetrans survives storage of potatoes, from which new infections may develop. Hence, potato tubers do appear to be an important means for the spread of P. penetrans to new areas.
Forfattere
Marit Larsen SekseSammendrag
The apple fruit moth (Argyresthia conjugella) is a serious pest in apples. It is a specialist seed predator of rowan, but the females will lay eggs on apples when rowan berries are scarce. Olfaction is important for many insect species in locating host plants. The odorant detection results from the association of odorous ligands with specific olfactory receptors, which are located in the membrane of the olfactory neurons. The aim of this work is to identify and characterize the odorant receptor genes and the genes involved in the regulation of the circadian olfactory response rhythm in the female apple fruit moth. In order to identify ORs, and other genes involved in olfaction, in the apple fruit moth a library of mRNA up-regulated in the antenna compared to the legs was made using subtractive hybridization. In total 864 clones have been sequenced. For 443 of the sequences no homology to known genes could be found using Blastx and blastn. Of the remaining sequences many have homology to genes that are known or believed to be involved in olfaction. These include odorant binding proteins, sensory neuron membrane proteins, chemosensory proteins, glutathione S-transferases, Odorant receptor 83b. This indicates that the subtraction has been successful and that the library is enriched in genes involved in olfaction. The sequences that it has not yet been possible to identify will be interesting for future studies.
Forfattere
Marit Larsen Sekse Sonja KlemsdalSammendrag
The apple fruit moth (Argyresthia conjugella) is a serious pest in apples. It is a specialist seed predator of rowan, but the females will lay eggs on apples when rowan berries are scarce. Olfaction is important for many insect species in locating host plants. The odorant detection results from the association of odorous ligands with specific olfactory receptors, which are located in the membrane of the olfactory neurons. The aim of this work is to identify and characterize the odorant receptor genes and the genes involved in the regulation of the circadian olfactory response rhythm in the female apple fruit moth. In order to identify ORs, and other genes involved in olfaction, in the apple fruit moth a library of mRNA up-regulated in the antenna compared to the legs was made using subtractive hybridization. In total 864 clones have been sequenced. For 443 of the sequences no homology to known genes could be found using Blastx and blastn. Of the remaining sequences many have homology to genes that are known or believed to be involved in olfaction. These include odorant binding proteins, sensory neuron membrane proteins, chemosensory proteins, glutathione S-transferases, Odorant receptor 83b. This indicates that the subtraction has been successful and that the library is enriched in genes involved in olfaction. The sequences that it has not yet been possible to identify will be interesting for future studies.
Forfattere
Xiaoren Chen Sonja Klemsdal May Bente BrurbergSammendrag
The oomycete Phytophthora cactorum causes crown rot disease in strawberry, resulting in big economic losses. To unravel the molecular mechanisms that are involved in the pathogenicity of P. cactorum on strawberry, two strategies were followed, SSH cDNA library and effector specific differential display. Two cDNA libraries were made, enriched for P. cactorum genes upregulated during infection of strawberry or genes expressed in in vitro germinating cyst (a developmental stage essential for infection). Subsets of the libraries were sequenced and some genes relevant to pathogenicity were found. Recent characterization of four oomycete AVR/effector genes revealed that they encode proteins with conserved RxLR-dEER motifs required for translocating these effectors into host cells. The presence of such a conserved "tag" has provided a tool for discovering the otherwise structurally diverse effector genes, and several hundred have been discovered in newly sequenced oomycete genomes. To select RxLR effector genes from P. cactorum differential display was performed on eight cDNA populations, including four developmental stages (mycelium, sporangium, zoospore and germinating cyst) as well as four time points during infection (0, 3, 5, 7 days post-inoculation), using the RxLR and EER motif degenerate primers. So far, 124 bands representing potentially infection-related genes were excised from the DD gels, cloned and sequenced.
Forfattere
Anne-Kristin Løes Chen He Elin Kaja Marley Bent Egberg MikkelsenSammendrag
iPOPY (innovative Public Organic food Procurement for Youth) er et internasjonalt forskningsprosjekt om økologisk mat til ungdommen i offentlige serveringstilbud, som f eks skolemat. Elever tilbringer stadig mer tid på skolen, og har behov for næringsrik og god mat i løpet av dagen. Samtidig øker problemer relatert til usunt kosthold, som overvekt og matintoleranse. Matservering i skolen har et stort potensiale til å lære elevene gode matvaner. Hovedmålet med iPOPY er å øke forbruket av økologisk mat gjennom offentlige matsreveringstilbud til ungdom. Hvordan kan slike tilbud legges opp på innovative måter? Ulike arbeidspakker undersøker varestrømmer, sertifiseringsordninger, involvering av elever og andre aktører og hvilket potensiale en innføring av økologisk mat har til å bedre elevenes kostvaner og helse. Prosjektperioden er 2007-2010 med en total økonomisk rmame på 1,4 mill. euro (ca 11 mill kr). Forskere fra Norge, Danmark, Finland, Tyskland og Italia deltar.
Forfattere
Anders Aak Anders AakSammendrag
Blowflies of the species Calliphora vicina are causing severe economic losses in dried fish production in northern Norway. Female flies are attracted to dead animals for both oviposition and foraging. As natural decomposing carcasses are scarce in its distribution and only suitable for the larvae a short time, the odour mediated resource location is expected to be very important. A wind tunnel was used to optimize attraction of female C. vicina and chemicals known to attract blowflies were tested both as single compounds and in blends. A three-component blend of dimethyltrisulphide, mercaptoethanol and o-cresol was found to significantly increase upwind orientation compared to the single attractant dimethyltrisulpide. More than 60% of female flies showed upwind oriented flight to the synthetic blend and this attraction was similar to decomposing liver which is commonly used to trap blowflies. Female attraction to odours from dead animals reached 90%, indicating a large potential for lure improvement. The three-component blend significantly increased field catches compared to dimethyltrisulphide, and the catch consisted of 98.2% females. A large scale mass trapping experiment in Lofoten, northern Norway, has now been ongoing for four years. Damage to stockfish in treated areas has significantly decreased compared to control areas.
Forfattere
Ricardo Holgado Stig Andersson Janet Rowe Ian Clark Christer MagnussonSammendrag
Norwegian cereal cyst nematode populations were studied by biochemical, molecular, morphological and bio test techniques. H. avenae occurred in the pathotypes, Ha11, Ha12, and H. avenae Våxtorp. H. filipjevi was recorded as pathotype West. H. avenae (Ha 11) and H. filipjevi West were the most common species. Thirty barley, 23 oat and 6 of summer wheat cultivars on the Norwegian market were tested for their resistance against H. avenae (Ha11), H. avenae Våxtorp and H. filipjevi West. Resistance against Ha11 was found in 5 barley, 3 oat and in 1 wheat cultivar. Resistance against H. avenae Våxtorp was not present in barley, but 4 oat and 1 wheat cultivar were resistant. For H. filipjevi West resistance was not detected in wheat, but in 6 barley and 13 oat cultivars. A management system based on careful nematode identification and knowledge on resistance of cultivars were set in operation in the county of Vestfold. As a result farmers have improved average yields by 1000 kg /ha. By implementing this program in full the county of Vestfold could make an annual gain of 800 000 €. In perspective of increasing damage from CCN world-wide the correct identification of species and the recognition of their genetic variability is instrumental for successful control.
Sammendrag
Plant polyphenolics continue to be the focus of attention with regard to their putative impact on human health. An increasing and ageing human population means that the focus on nutrition and nutritional enhancement or optimization of our foodstuffs is paramount. Using raspberry as a model we have shown how modern metabolic profiling approaches can be used to identify the changes in the level of beneficial polyphenolics in fruit breeding segregating populations and how the level of these components are determined by genetic and/or environmental control. Interestingly the Vitamin C content appeared to be significantly influenced by environment (growth conditions) whilst the content of the polyphenols such as cyanidin, pelargonidin and quercetin glycosides appeared to much more tightly regulated suggesting a rigorous genetic control. Preliminary metabolic profiling showed that the fruit polyphenolic profiles divided into two gross groups segregating on the basis of relative levels of cyaniding-3-sophoroside and cyaniding-3-rutinoside, compounds implicated as conferring human health benefits.
Forfattere
Per Stålnacke Annelene Pengerud Marianne Bechmann Josette Garnier Christoph Humborg Vladimir NovotnySammendrag
The major objective of this study was to compile and examine empirical relationships between the driving forces and pressures that affect nitrogen cycling. Special attention was paid to riverine loads, fluxes, and concentrations of nitrogen in relation to agricultural factors (e.g., land use and fertilisers) at various spatial scales (plot, field, catchment, river basin, nation, region, continent, and world). Results of the present analyses and assessments reported in the literature indicate that at global, continental and inter-river basin scales, the level of riverine nitrogen loads (pressures) can be readily derived from simple empirical relationships with driving forces like population density and agricultural factors (e.g., proportion of arable land and fertiliser use). It seems that statistically derived relationships do not hold or are much weaker at the scales of single river basins and smaller catchments, whereas nitrogen losses appear to be correlated with fertiliser use at the smallest scales (plot and field). It is important to recognize this spatial nutrient paradox, particularly when such functional relationships are applied in the contexts of management and decision making. The implications for management are given further consideration in this paper.