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.
2012
Forfattere
Jonathan Edward Colman Diress Tsegaye Alemu Christian Pedersen Ruben Eidesen Herbjørg Arntsen Øystein Holand Alex Mann Eigil Reimers Stein Ragnar MoeSammendrag
Interspecific interaction among sympatric ungulates is important in management and conservation. We investigated behavioral interference between sympatric wild or semidomestic reindeer (Rangifer tarandus tarandus) and sheep (Ovis aries) in two field studies and one enclosure experiment. For free-ranging wild and semidomestic reindeer, interference between the two species increased with decreasing distances, occurring only at less than 200 m and 30 m, for wild and semidomestic reindeer, respectively, and neither species consistently dominated the other. In a controlled, duplicated experiment we tested interference and confrontations at the feeding patch level among semidomestic reindeer and sheep within 40 × 50 m enclosures. When new reindeer or sheep were introduced into enclosures already occupied by reindeer, new reindeer resulted in significantly more interference and confrontations among individuals compared to new sheep; i.e., intraspecific interference was more prevalent than interspecific interference at equal densities. For all study areas, confrontations decreased with time after “first encounter,” indicating cohabituation. A sympatric use of pastures was not visually disruptive for recorded grazing behavior for either species.
Forfattere
Igor A. Yakovlev Gustav Vaaje-Kolstad Ari Hietala Emil Stefanczyk Halvor Solheim Carl Gunnar FossdalSammendrag
Det er ikke registrert sammendrag
Sammendrag
Residues of pharmaceuticals present in wastewater and sewage sludge are of concern due to their transfer to aquatic- and terrestrial food chains and possible adverse effects on non-targeted organisms. In the present work, uptake and translocation of metformin, an anti-diabetic II medicine, by edible plant species cultivated in agricultural soil has been investigated in greenhouse experiment. Metformin demonstrated a high uptake and translocation to oily seeds of rape (Brassica napus cv. Sheik and Brassica rapa cv. Valo). Expressed as an average bioconcentration factor, (BCF, plant concentration over initial concentration in soil, both in dry weight), BCF as high as 21.72 was measured. In comparison, BCFs for grains of the cereals wheat, barley and oat were in the range of 0.29 - 1.35. Uptake and translocation to fruits and vegetables of tomato (BCFs 0.02-0.06), squash (BCFs 0.12-0.18) and bean (BCF 0.88) were also low compared to rape. BCFs for carrot, potato and leaf forage Brassica napus cv. Sola were similar (BCF 1-4). Guanylurea, a known degradation product of metformin by microorganisms in activated sludge, was found in seeds from barley, beans and potatoes. The mechanisms for transport of metformin and guanidine in plants are still unknown, whereas organic cation transporters (OCTs) in mammals are known to actively transport such compounds and may guide the way for further understanding of mechanisms also in plants.
Forfattere
Nina Elisabeth Nagy Harald Kvaalen Monica Fongen Carl Gunnar Fossdal Nicholas Clarke Halvor Solheim Ari HietalaSammendrag
Pathogen challenge of tree sapwood induces the formation of reaction zones with antimicrobial properties such as elevated pH and cation content. Many fungi lower substrate pH by secreting oxalic acid, its conjugate base oxalate being a reductant as well as a chelating agent for cations. To examine the role of oxalic acid in pathogenicity of white-rot fungi, we conducted spatial quantification of oxalate, transcript levels of related fungal genes, and element concentrations in heartwood of Norway spruce challenged naturally by Heterobasidion parviporum. In the pathogen-compromised reaction zone, upregulation of an oxaloacetase gene generating oxalic acid coincided with oxalate and cation accumulation and presence of calcium oxalate crystals. The colonized inner heartwood showed trace amounts of oxalate. Moreover, fungal exposure to the reaction zone under laboratory conditions induced oxaloacetase and oxalate accumulation, whereas heartwood induced a decarboxylase gene involved in degradation of oxalate. The excess level of cations in defense xylem inactivates pathogen-secreted oxalate through precipitation and, presumably, only after cation neutralization can oxalic acid participate in lignocellulose degradation. This necessitates enhanced production of oxalic acid by H. parviporum. This study is the first to determine the true influence of white-rot fungi on oxalate crystal formation in tree xylem.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Long-term and varied land use has had a major influence on the vegetation in rural Norway, and the traditional open landscapes are now being replaced by forests. In the present investigation, we assess and quantify structural vegetation changes caused by changes in land use and climate. Up-to-date actual vegetation maps from three rural study areas were compared with interpreted historical vegetation maps and potential natural vegetation (PNV) models. Our findings indicate that the present vegetation structure is strongly influenced by land use. In the studied sites, 56–66% of the areas presently have another vegetation type than expected from a natural state (PNV). The mean turnover of vegetation types in the study areas during the past 35–40 years was 25%. Our study highlights that the influence of land-use needs to be accounted for when considering the effects of climate change.
Forfattere
Igor A. Yakovlev Carl Gunnar Fossdal Tore Skrøppa Jorunn Elisabeth Olsen Anne Hopen Jahren Øystein JohnsenSammendrag
Conifers are evolutionarily more ancient than their angiosperm counterparts, and thus some adaptive mechanisms and features influenced by epigenetic mechanisms appear more highly displayed in these woody gymnosperms. Conifers such as Norway spruce have very long generation times and long life spans, as well as large genome sizes. This seemingly excessive amount of genomic DNA without apparent duplications could be a rich source of sites for epigenetic regulation and modifications. In Norway spruce, an important adaptive mechanism has been identified, called epigenetic memory. This affects the growth cycle of these trees living in environments with mild summers and cold winters, allowing them to adapt rapidly to new and/or changing environments. The temperature during post-meiotic megagametogenesis and seed maturation epigenetically shifts the growth cycle programme of the embryos. This results in significant and long-lasting phenotypic change in the progeny, such as advance or delay of vital phenological processes of high adaptive value, like bud break and bud set. This phenomenon is not only of important evolutionary significance but has clear practical implications for forest seed production and conservation of forest genetic resources. The underlying molecular mechanism that causes the ‘memory’ in long-lived woody species is currently under investigation. Here we summarize the information related to epigenetic memory regulation in gymnosperms, with special emphasis on conifers. The molecular mechanism behind this is still unknown but transcriptional changes are clearly involved. Epigenetic regulation may be realized through several mechanisms, including DNA methylation, histone modification, chromatin remodelling, small non-coding RNAs and transposable element regulation, of which non-coding RNAs might be one of the most important determinants.
Forfattere
Venche Talgø Iben Margrete Thomsen UB Nielsen May Bente Brurberg Arne Stensvand Thomas CechSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Storfuglen (tiur og røy) er ofte blitt betegnet som en `gammelskogart`. Tre årtier med skogsfuglforskning på Varaldskogen har imidlertid vist at den har klart overgangen til yngre kulturskog bedre enn ventet. Det betyr likevel ikke at alt er `såre vel`.