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
Abstract
No abstract has been registered
Authors
Geir Mathiesen Anita Sveen May Bente Brurberg Lasse Fredriksen Lars Axelsson Vincent EijsinkAbstract
Conclusion: This is the first comprehensive experimental study showing that predicted SPs in the L. plantarum genome actually are capable of driving protein secretion. The results reveal considerable variation between the SPs that is at least in part dependent on the protein that is secreted. Several SPs stand out as promising candidates for efficient secretion of heterologous proteins in L. plantarum. The results for NucA provide some hints as to the sequence-based prediction of SP functionality, but the general conclusion is that such prediction is difficult. The vector library generated in this study is based on exchangeable cassettes and provides a powerful tool for rapid experimental screening of SPs.
Authors
Geir Mathiesen Anita Sveen May Bente Brurberg Lasse Fredriksen Lars Axelsson Vincent EijsinkAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Ole Martin Eklo Randi Bolli Jens Kværner Tore Sveistrup Frauke Hofmeister Eivind Solbakken Nicolas Jarvis Fredrik Stenemo Eirik Romstad Borghild Glorvigen Tor Anton GurenAbstract
No abstract has been registered
Abstract
Minirhizotrons, transparent acrylic tubes inserted in the soil, are well suited for long term, non destructive, in situ observations of fine roots. In minirhizotrons, the fine roots are regularly photographed and the root images are visually evaluated according to their status as living, dead or disappeared. This evaluation gives the background for further statistical treatment to estimate the fine root longevity. It is inherent in the minirhizotron technique that a large group of roots will be described as “disappeared” due to grazing, overgrowing by other roots, unclear images or other reasons. Because the fraction of disappeared roots is substantial in some cases, this has consequences for the interpretation of the longevity results. We processed three years of minirhizotron images from Norway spruce stands in southeast Norway (30 yr old) and northern Finland (60 yr old). Of all processed fine roots 32 and 23% was evaluated as disappeared in Norway and Finland, respectively. When roots labelled as disappeared were pooled together with dead ones, the fine root longevity estimates, using the Kaplan Meier method, decreased almost by a factor of two (401 and 433 days), as opposed to labeling them as censored observations (770 and 750 days for Norway and Finland, respectively). Here we demonstrate how the early decision making on the fine root status bears consequences on the resulting longevity estimates. The implications will be discussed
Abstract
No abstract has been registered
Authors
Carl Gunnar Fossdal Igor A. Yakovlev Ari M. Hietala Halvor SolheimAbstract
To identify differentially expressed genes of the white-rot fungus Heterobasidion parviporum subtractive cDNA libraries were constructed using suppressive subtraction hybridization (SSH) technique with RNA extracted from an advanced stage of decay area and from colonization front next to the reaction zone of the stem of a mature Norway spruce trees. Besides cytochrome P450s and proteins with unknown function, the SSH libraries constructed contained genes involved in basic cellular processes, andcell wall degradation. To examine the role of selected candidate genes three trees, showing a variable degree of wood decay, were used for real-time RT-PCR profiling of candidate genes. In the decay transition areas the study revealed activity centers that showed remarkable similarity in the transcript profiles of monitored genes.
Authors
Åke Olson Mikael Brandström Kajsa Himmelstrand Mårten Lind Magnus Karlsson K. Lunden Kerstin Dalman Heriberto Vélëz Björn Canbäck Francis Martin Halvor Solheim Carl Gunnar Fossdal Pierre Rouzé Yao-Cheng Lin Matteo Garbelotto Ursula Kües Igor V. Grigoriev Andrea Aerts Erika Lindquist Jeremy Schmutz Jan StenlidAbstract
The genome sequence of the conifer rot root pathogen Heterobasidion annosum was generated at JGI with 8.23 X coverage. The nuclear genome assembles in 39 scaffolds of total 33.7 Mbp estimated to cover 98.1% of the complete genome. We predicted 12,270 genes with an average length of 1,617 bp and exon number and length of 5.54 and 250 bp respectively. About 50% (5999) of the predicted genes could be validated by EST support with the 40,807 EST´s generated with in the project. The genome has a GC content of 52.0% and very little repetitive sequences with 2,895 SSR per mega base. The physical genome is congruent with the genetic linkage map, and most of the linkage groups have been possible to anchor to the 18 largest scaffolds.
Authors
Nadeem Yaqoob Carl Gunnar Fossdal Jan Karlsson Benedicte Riber Albrectsen Halvor SolheimAbstract
Due to the great economic losses caused by the root and butt-rot pathogen Heterobasidion annosum, development of efficient control measures is warranted. H. annosum a necrotroph colonize the Norway spruce from inside and is responsible for 100s of millions of Euros losses annually. Considerable clonal variation has been recorded for Norway spruce in resistance towards H. annosum, but the defence mechanisms contributing to host resistance against both necrotrophic and biotrophic fungi remain poorly understood. The recent genome sequencing of Populus has made the genus a model to facilitate tree genetics. Genome-wide transcript profiling of Populus tremula upon pathogen attack will now be used, and homologues of Norway spruce genes to defence genes up-regulated in Populus will be identified. Two aspen clones (23 and 72) from the SwAsp collection (Luquez 2007) were used in the present study. Plants were propagated from tissue culture and kept in greenhouse under un-manipulated conditions. To study the host defence mechanisms, the rust (Melampsora magnusiana Wagner) and a bluestain fungus were used as a biotrophic and necrotrophic fungus respectively. Melampsora spores solution was applied to the underside of the leaf. To control for sectoriality six leaves were infected on each plant. To ensure high humidity and avoid cross contamination, plastic bags were wrapped around infected leaves. Leaves above infected leaves (10, 9, and 8) were harvested respectively 1, 3 and 14 days after inoculation. Initial results from microarray data indicate a clear separation between two Aspen clone (23 and 72) lines. For line 23 the response to biotroph and necrotroph seems to be similar. Whereas the response for line 72 is divergent for the treatments as they go in opposite direction. The controls show that there is an initial difference in the 2 lines (controls are separated). What are the genes that make biotrohic and necrotrophic treatment of 72 look so different will be worked out from microarray data. Differential expression of defense genes in biotrohic and necrotrophic treatment will be verified further with quantitative real time PCR. Chemical analysis of Aspen leaves gave less phenolic compounds as plants were kept in greenhouse. HPLC will be carried out after reaching some conclusion from microarray data analysis.