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.
2010
Sammendrag
Development of ontogenic resistance to powdery mildew (Podosphaera aphanis) on strawberry leaves has been reported, however, the components of resistance have not been elucidated. Five developmental stages of strawberry leaves were identified and assigned numerical values from newly emerged and unexpanded (S1) to fully expanded and dark green (S5) of cvs. Korona and Senga Sengana. The upper and lower surface of the leaves were inoculated from each of the five leaf developmental stages and incubated under controlled conditions. The effect of leaf age on germination, infection efficiency, latency period, and sporulation were later evaluated. All responses were significantly (p = 0.05) affected by leaf age. Germination percentage, infection efficiency, and sporulation were highest, and latent periods were shortest on S1 leaves of both cultivars. On Senga Sengana, germinating conidia produced fewer secondary hyphae during infection. Conidia produced very few secondary hyphae and did not sporulate on S3 leaves, and no infections established on S4 or S5 leaves. The high success of infection and colonization of P. aphanis on S1 leaves indicates that disease is established preferentially on emergent and expanding leaves and these should be the target of management strategies.
Forfattere
Kirsten TørresenSammendrag
Det er ikke registrert sammendrag
Sammendrag
Green algae are known to produce H2 under sulphur deprivation in a process called biophotolysis, where solar energy is used to split water and generate O2 and H2. There is still considerable potential for improvement and very little is known about how this mechanism varies between species. This is part of Bioforsk research activities linked to green algae and H2 production. In order to make a H2 production process from algae economically viable, we face several challenges, including bioreactor design, optimisation of environmental conditions, efficiency improvement by genetic and metabolic engineering. One possibility for improving the economical potential of a hydrogen production process also includes exploitation of the algal biomass which, as a result of stress reactions, may produce metabolites with pharmaceutical value. Joining forces with The Norwegian University of Life Science (UMB) and The Norwegian Forest and Landscape Institute, Bioforsk has established The Norwegian Centre for Bioenergy Research. Bioforsk has also taken a leading role on biogas in the newly established CenBio - a national Centre for Environmental- friendly Energy Research. The modern biogas laboratories are located close to facilities for plant growth studies, making them easy accessible for experimental studies of the entire chain from biomass to fertiliser. Research activities include innovative pre-treatment of substrates for increased biogas yield, effects of substrate mixtures for biogas production and digestate quality, biogas potential and biogas process studies, digestates as fertiliser, and effects on the environment and climate
Forfattere
Kari SkjånesSammendrag
Green microalgae can be used for a number of commercial applications, including health food for human consumption, aquaculture and animal feed, coloring agents, cosmetics and pharmaceuticals. Several products from green algae that are in use today, consist of metabolites which can be extracted from the algal biomass. The most well known examples are the carotenoids astaxanthin and Β-carotene, which are used as coloring agents and for health promoting purposes. Many species of green algae are able to produce valuable components for different uses, examples are antioxidants, several different carotenoids, polyunsaturated fatty acids, vitamins, anticancer and antiviral drugs. In many cases these components are secondary metabolites which are produced when the algae are exposed for stress conditions like for example nutrient deprivation, light intensity, temperature, salinity, pH and other. In other cases the components have been detected in algae grown under optimal conditions, and little is known about how an optimal production of each product could be induced and how their production would react to stress conditions. Some green algae have shown the ability to produce significant amounts of hydrogen gas during sulfur deprivation, a process which is currently extensively studied. At the moment, the majority of research in this field has focused on the model organism Chlamydomonas reinhardtii, but other species of green algae have also showed this ability. Currently there is scarce information available regarding the possibility for producing hydrogen and other valuable components in the same process. This study explores stress conditions which are known to induce production of the different valuable products in comparison with stress reactions leading to hydrogen production. Wild type species of green microalgae with ability to produce hydrogen during anaerobic conditions, and during sulfur deprivation are compared to species with known ability to produce high amounts of certain valuable metabolites. . This information is explored in order to form a basis for selection of wild type species for a future multidiciplinary process, where hydrogen production from solar energy is combined with production of valuable metabolites and other commercial uses of the algal biomass.
Forfattere
Kari SkjånesSammendrag
Det er ikke registrert sammendrag
Sammendrag
The production of hydrogen in green algae is catalyzed by FeFe- hydrogenases, which have high conversion efficiency and high oxygen sensitivity. Most green algae analyzed to date where hydrogenase genes are detected, have been shown to contain two distinct hydrogenases. However, very little is known about which functions the two different enzymes represent. There are also many unknowns within the mechanisms behind hydrogen production as to the roles hydrogenases play under different conditions, and consequently also about the potential for optimization of a hydrogen production process which could be found in this respect. The presented study focuses on the possibility for presence of more than two hydrogenases in a single green alga. A large number of degenerate primers were designed and used to produce 3"-RACE products, which in turn were used to design gene specific primers used for PCR and 5"-RACE reactions. The sequences were aligned with known algal hydrogenases to identify products which had homology to these. Products where homology was identified were then explored further. A high number of clones from each band were sequenced to identify products with similar lengths which would not show up as separate bands on a gel. Sequences found to have homology with algal hydrogenases were translated into putative amino acid sequences and analyzed further to obtain detailed information about the presence of specific amino acids with known functions in the enzyme. This information was used to evaluate the likelihood of these transcripts coding for true hydrogenases, versus hydrogenase-like or narf-like proteins. Conclusion: Evidence showing that Chlamydomonas noctigama is able to transcribe three genes which share a significant number of characteristics with other known algal FeFe-hydrogenases is presented . The three genes have been annotated hydA1, hydA2 and hydA3.
Forfattere
Brita Toppe Maria HerreroSammendrag
I 2005 ble Phytophthora ramorum funnet på rododendron i parken på Gamlehaugen. I et felt med gamle, 2-3 meter høye planter med tykke stammer og greiner syntes sykdommen å ha forårsaket mest skade. Funnet ga oss anledning til å undersøke mærmere hvordan smitte av P. ramorum overlever i jord.
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Christer MagnussonSammendrag
Det er ikke registrert sammendrag
Forfattere
Christer MagnussonSammendrag
Det er ikke registrert sammendrag