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.
2009
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Six clones of Rhodiola rosea, obtained from plants originating from widely different areas in Norway, were investigated for their in vitro inhibitory potential on CYP3A4-mediated metabolism and P-gp efflux transport activity. Presumed active constituents in the ethanol extracts of the different clones were quantified. C-DNA baculovirus expressed CYP3A4 and Caco-2 cells were used for inhibitory assays, and as positive control inhibitors ketoconazole and verapamilwere applied, respectively. A validated HPLC methodology was used to quantify the formation of 6-β-OH-testosterone and scintillation counting was used to quantify the transport of 3H-digoxin in Caco-2 cells. All clones showed potent inhibition of CYP3A4 and P-gp activities, with IC50 values ranging from 1.7 to 3.1 μg/mL and from 16.7 to 51.7 μg/ mL, respectively, being below that reported for other herbs and some known classic drug inhibitors, such as St. John’s wort and fluoxetine. Rhodiola rosea might thus be a candidate for clinically relevant drug interactions. The concentration of presumed biologically active constituents in the different clones varied considerably, but this variationwas not related to the clones’ inhibitory potential on CYP3A4 or P-gp activities. Other constituents might thus be responsible for the observed inhibitory properties. The place of origin seemed to be of minor importance for CYP3A4 or P-gp inhibition.
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Diversity of clovers in grass-clover swards may contribute to greater herbage yields and stability of yield. This possible effect was evaluated in an experiment carried out over three harvest years at two contrasting sites, differing in precipitation and soil composition, using mixed swards containing either one, two or three clover species sown together with timothy (Phleum pratense L.) and meadow fescue (Festuca pratensis L.). The clover species were red clover (Trifolium pratense L.), white clover (Trifolium repens L.) and alsike clover (Trifolium hybridum L.) sown in various proportions in a total of ten treatments. All swards were fertilized with nitrogen with amounts that increased from year to year, and three harvests were taken in three consecutive years. There was a significant interaction between site and species mixture on total dry matter (DM) yields (range 27-32 tonnes ha-1) and DM yields of clovers (range 5-15 tonnes ha-1); red clover as a single species or in a mixture was superior at the dry site while multi-clover species mixtures were superior at the wet site. Alsike clover was the least productive species of clover. Stability of yield of clovers was generally higher by including white and red clover in the seed mixture but total DM yield was not.
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No abstract has been registered
Authors
Kristine Marie Olsen Rune Slimestad Unni Synnøve Lea Cato Brede Trond Karsten Løvdal Peter Ruoff Michel Verheul Cathrine LilloAbstract
The flavonoid pathway is known to be up-regulated by different environmental stress factors. Down-regulation of the pathway is much less studied and is emphasized in the present work. Flavonoid accumulation was induced by exposing plants for 1 week to nitrogen depletion at 10 degrees C, giving high levels of anthocyanins and 3-glucoside-7-rhamnosides, 3,7-di-rhamnosides and 3-rutinoside-7-rhamnosides of kaempferol and quercetin. Flavonol accumulation as influenced by temperatures and nitrogen supply was not related to the glycosylation patterns but to the classification as quercetin and kaempferol. When nitrogen was re-supplied, transcripts for main regulators of the pathway, PAP1/GL3 and PAP2/MYB12, fell to less than 1 and 0.1% of initial values, respectively, during 24 h in the 15-30 degrees C temperature range. Anthocyanins showed a half-life of approximately 1 d, while the degradation of flavonols was much slower. Interestingly, the initial fluxes of anthocyanin and flavonol degradations were found to be temperature-independent. A kinetic model for the flavonoid pathway was constructed. In order to get the observed concentration-temperature profiles as well as the temperature compensation in the flavonoid degradation flux, the model predicts that the flavonoid pathway shows an increased temperature sensitivity at the end of the pathway, where the up-regulation by PAP/GL3 has been found to be largest.
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Analysing forest history is crucial to understanding how shifting harvesting methods have different effects on forest landscape structure. Two main harvesting regimes in a Norwegian boreal forest landscape over a period of 150 years were detected by the study. A homogeneous impact regime resulting from selective logging changed the forest structure by logging the oldest and largest trees evenly throughout the forest, resulting in a homogeneous landscape structure. However, population growth in the 19th century led to a substantial increase in traditional subsistence forestry to obtain building materials, firewood, etc. The most intensive stage of this regime started in c.1860 when farmers began selling logging contracts to companies and timber traders. Despite this being termed a homogeneous landscape impact, the actual exploitation of the forest was strongly influenced by local factors such as the location of farms, summer farms, lakes, and rivers. Clear-cutting from the 1950s has resulted in a new heterogeneous impact regime, giving a landscape structure dominated by patches of even-aged stands. This regime still predominates. The analysis is based on a study of Nordli and the Sandøla drainage basin in Nord-Trøndelag. Such studies should give a better understanding of the interaction between natural ecological conditions in and human impact on boreal forest landscapes.
Abstract
Two female and two male cultivars have previously been released as a result of clone evaluation at Bioforsk Nord Holt. The selection criteria were the number of pistils or stamens per flower, the number of flowers and the number of shoots per m2. Currently a new group of clones are being evaluated with the aim of finding new cultivars for release. The preliminary results on flowering and berry production show a strong variance in these traits. Over three years of registration, the number of produced flowers varied from under 100 for the weakest clone to more than 1000 for the best clone. The number of produced berries varied from 9 for the weakest clone to 242 for the best clone. The three clones that produced the most flowers all had very low berry production and deviated from the rest of the clones by having high numbers of flowers per harvested berry. New selection criteria will be considered before selection of new cultivars for release. In addition to the production traits, new selection criteria will most likely include berry contents, such as the levels of antioxidants.