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Økstad, Ole Andreas
(2023).
The dynamic trio - the good, the bad and the ugly.
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Økstad, Ole Andreas
(2023).
Reversing carbapenem resistance in Gram-negative pathogens - Preclinical development of the modular synthetic metallo-β-lactamase inhibitor APC148.
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Ambur, Ole Herman; Skaare, Dagfinn & Økstad, Ole Andreas Løchen
(2023).
Alginate polymer alters susceptibility of biofilm-embedded non-typable Haemophilus influenzae .
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Glenna, S; Orr, Russell John Scott; Økstad, Ole Andreas & Voie, ØA
(2023).
Changes in the skin microbiome in response to antiseptic use during a NATO exercise: a metagenomic approach.
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Urtubia, Areli Moe; Winther-Larsen, Hanne Cecilie & Økstad, Ole Andreas
(2023).
Novel principles of drug resistance in the WHO priority 1 pathogen Acinetobacter baumannii.
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Smith, V; Hovland, R; Rongved, Pål & Økstad, Ole Andreas
(2023).
Preclinical development of a novel metallo-β-lactamase inhibitor APC148.
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Linke, Dirk; Økstad, Ole Andreas; Haugen, Håvard Jostein & Winther-Larsen, Hanne Cecilie
(2021).
The exchange program MISC - Options for internships at the University of Oslo (with descriptions of current projects).
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Liskiewicz, Krystyna Anna; Sunde, Pia Titterud; Verket, Anders; Økstad, Ole Andreas & Simm, Roger
(2019).
C-di-GMP signaling in Treponema denticola and its role in pathogenesis of periodontal diseases.
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Liskiewicz, Krystyna Anna; Sunde, Pia Titterud; Verket, Anders; Økstad, Ole Andreas & Simm, Roger
(2019).
C-di-GMP signaling in Treponema denticola and its role in pathogenesis of periodontal diseases.
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Økstad, Ole Andreas Løchen & Linke, Dirk
(2018).
Hvor farlig er antibiotikaresistens?
Ingeniørenes Stemme.
Vinter 2018,
s. 37–37.
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Heggelund, Julie Elisabeth; Hausvik, Emil; Carvalho, Luiz; Økstad, Ole Andreas Løchen; Martinez, Aurora & Goldman, Adrian
(2018).
Targeting MFS transporters to switch off antibiotic resistance in tuberculosis.
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Heikal, Adam; Samuelsen, Ørjan; Kristensen, Tom & Økstad, Ole Andreas Løchen
(2017).
Complete genome sequence of a multidrug-resistant, blaNDM-1-expressing Klebsiella pneumoniae K66-45 clinical isolate from Norway.
Microbiology Resource Announcements (MRA).
ISSN 2169-8287.
5:e00601(27),
s. 1–2.
doi:
10.1128/genomeA.00601-17.
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Ho, Giang Thanh Thi; Braünlich, Marie; Økstad, Ole Andreas Løchen; Slimestad, Rune; Wangensteen, Helle & Malterud, Karl Egil
[Vis alle 7 forfattere av denne artikkelen]
(2015).
Effects of Aronia melanocarpa on biofilm formation of Escherichia coli and Bacillus cereus.
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Ho, Giang Thanh Thi; Braünlich, Marie; Wangensteen, Helle; Malterud, Karl Egil; Økstad, Ole Andreas Løchen & Christensen, Hege Staaland
[Vis alle 9 forfattere av denne artikkelen]
(2014).
Spennende helseeffekter av aroniabær.
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Røhr, Åsmund Kjendseth; Fagerlund, Annette; Økstad, Ole Andreas Løchen & Andersson, K. Kristoffer
(2013).
Characterization of a redox sensor involved in Bacillus cereus biofilm formation.
NBS-nytt.
ISSN 0801-3535.
1,
s. 62–62.
Vis sammendrag
The facultative aerobic, opportunistic human pathogen, Bacillus cereus is known to form biofilm under certain conditions. A common mechanism for biofilm formation depends on cyclic 3’-5’-cyclic diguanylic acid (c-di-GMP) signaling. The second messenger c-di-GMP is synthesized and degraded by the protein domains GGDEF and EAL, respectively. In order to regulate the activity of such GGDEF and EAL domains, these can be coupled to various PAS domains that act as environmental sensors of e.g. redox potential or oxygen concentration.
We aim to understand how sensory PAS domains regulate the enzymatic activity of GGDEF and EAL domains through inter- or intra protein mediated interactions. The protein BC0628 from B. cereus ATCC 14579 was selected as a model system because it has a PAS-GGDEF-EAL domain structure and putative sensory, diguanylate cyclase, and phosphodiesterase activities.
Here we present results showing that the soluble purified enzyme appears to bind a redox active flavin cofactor in the PAS domain. Activity assays also show that both GGDEF and EAL domains are functional and that their activities are tuned by the redox state of the PAS domain flavin cofactor. Results from initial crystallization screening are positive, thus, the BC0628 appears to be good model candidate for functional PAS-GGDEF-EAL proteins and future structural studies.
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Økstad, Ole Andreas Løchen & Tourasse, Nicolas
(2009).
Genome dynamics in the Bacillus cereus group of bacteria: introns and repeats.
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Kolstø, Anne-Brit; Økstad, Ole Andreas Løchen; Tourasse, Nicolas; Kristoffersen, Simen Martens; Fægri, Karoline & Fagerlund, Annette
(2009).
Bacillus cereus group: genome plasticity for better adaptation.
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Kolstø, Anne-Brit; Tourasse, Nicolas; Økstad, Ole Andreas Løchen; Fægri, Karoline & Fagerlund, Annette
(2009).
Bacillus cereus gene regulation and pathogenomics.
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Økstad, Ole Andreas Løchen
(2009).
Differential gene expression and gene regulation during biofilm formation in Bacillus thuringiensis.
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Tourasse, Nicolas; Helgason, Erlendur; Klevan, Leif Are; Sylvestre, Patricia; Moya, Maryse & Haustant, Michel
[Vis alle 10 forfattere av denne artikkelen]
(2009).
Global multi-datatype phylogenetic analysis of the Bacillus cereus group reveals new lineages and clusters.
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Kristoffersen, Simen Martens; Tourasse, Nicolas; Bakka, Eirik Rødseth; Read, Timothy D.; Kolstø, Anne-Brit & Økstad, Ole Andreas Løchen
(2009).
Repeated DNA elements in the Bacillus cereus group - implications for genome dynamics and stability of messenger RNA.
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Fagerlund, Annette; Kolstø, Anne-Brit & Økstad, Ole Andreas Løchen
(2009).
Differential gene expression and gene regulation during Bacillus thuringiensis biofilm formation.
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Økstad, Ole Andreas Løchen; Klevan, Leif Are; Tourasse, Nicolas; Kristoffersen, Simen Martens; Langørgen, Heidi K. & Stabell, Fredrik Bernhard
[Vis alle 7 forfattere av denne artikkelen]
(2008).
Mobile chromosomal repeat elements in Bacillus cereus, B. thuringiensis, and B. anthracis − Comparative genomics and transcriptional analysis.
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Økstad, Ole Andreas Løchen
(2008).
Bacillus anthracis, B. cereus, and B. thuringiensis − pathogenic spore-forming bacteria ACTing out an identity crisis.
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Klevan, Leif Are; Tourasse, Nicolas; Kristoffersen, Simen Martens; Langørgen, Heidi K.; Stabell, Fredrik Bernhard & Kolstø, Anne-Brit
[Vis alle 7 forfattere av denne artikkelen]
(2008).
Mobile chromosomal repeat elements in pathogenic Bacilli − comparative genomics of isolates closely related to Bacillus anthracis and co-transcription with neighbour genes.
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Kristoffersen, Simen Martens; Tourasse, Nicolas; Klevan, Leif Are; Bakka, Eirik Rødseth; Kolstø, Anne-Brit & Økstad, Ole Andreas Løchen
(2008).
The Mobile Chromosomal Repeat Element bcr1in Bacillus cereus Stabilizes Adjacent mRNAs.
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Tourasse, Nicolas; Økstad, Ole Andreas Løchen; Stabell, Fredrik Bernhard; Kristoffersen, Simen Martens & Kolstø, Anne-Brit
(2008).
Genome dynamics in Bacillus cereus − Bacillus anthracis − Bacillus thuringiensis.
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Kristoffersen, Simen Martens; Klevan, Leif Are; Tourasse, Nicolas; Langørgen, Heidi K.; Stabell, Fredrik Bernhard & Kolstø, Anne-Brit
[Vis alle 7 forfattere av denne artikkelen]
(2008).
The mobile chromosomal repeat element bcr1 from the Bacillus cereus group is co−transcribed with neighboring genes and predicted to fold into a double hairpin−like structure.
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Økstad, Ole Andreas Løchen; Klevan, Leif Are; Tourasse, Nicolas; Kristoffersen, Simen Martens; Langørgen, Heidi K. & Stabell, Fredrik Bernhard
[Vis alle 7 forfattere av denne artikkelen]
(2008).
Mobile chromosomal repeat elements in pathogenic bacilli − comparative genomics and transcriptional analysis.
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Økstad, Ole Andreas Løchen & Kolstø, Anne-Brit
(2007).
Bacillus ACT 2007 - Oslo, 17-21 June 2007.
NBS-nytt.
ISSN 0801-3535.
s. 28–30.
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Økstad, Ole Andreas Løchen & Kolstø, Anne-Brit
(2007).
Mikrobiologi-konferanse i FI-regi.
Norsk Farmaceutisk Tidsskrift.
ISSN 0029-1935.
s. 10–10.
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Økstad, Ole Andreas Løchen; Ravel, Jacques; Rasko, David A; Rosovitz, MJ; Tourasse, Nicolas & Kolstø, Anne-Brit
(2007).
Comprehensive whole genome sequence analysis of clinical Bacillus cereus isolates from different human infections.
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Økstad, Ole Andreas Løchen; Klevan, Are; Tourasse, Nicolas; Stabell, Fredrik Bernhard; Kristoffersen, Simen Martens & Kolstø, Anne-Brit
(2007).
Mobile chromosomal repeat elements unique to the Bacillus cereus group − chromosomal organization, transcription, and secondary structure.
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Kristoffersen, Simen Martens; Ravnum, Solveig; Tourasse, Nicolas; Økstad, Ole Andreas Løchen; Kolstø, Anne-Brit & Davies, William
(2007).
Gene transcription responses to bile salts in Bacillus cereus ATCC 14579 – in vitro modeling of GI-tract bile exposure.
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Økstad, Ole Andreas Løchen; Tourasse, Nicolas; Hegna, Ida Kristin & Kolstø, Anne-Brit
(2007).
Functional and comparative genomics in pathogenic Bacillus species.
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Fægri, Karoline; Hegna, Ida Kristin; Økstad, Ole Andreas Løchen & Kolstø, Anne-Brit
(2007).
Comparative analysis of global gene expression in Bacillus cereus ATCC 14579 and a deletion mutant of a membrane transporter with similarity to tetracycline resistance genes.
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Økstad, Ole Andreas Løchen; Klevan, Are; Tourasse, Nicolas; Stabell, Fredrik Bernhard & Kolstø, Anne-Brit
(2007).
Mobile chromosomal repeat elements in Bacillus cereus, B. thuringiensis and B. anthracis.
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Biørnstad, Truls Johan; Jensen, Christine; Gohar, Michel; Kolstø, Anne-Brit & Økstad, Ole Andreas Løchen
(2007).
Biofilm formation in Bacillus cereus group pathogens − screening of isolates and functional dissection of candidate genes potentially involved in the process.
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Klevan, Are; Kristoffersen, Simen Martens; Langørgen, Heidi K.; Tourasse, Nicolas; Stabell, Fredrik Bernhard & Kolstø, Anne-Brit
[Vis alle 7 forfattere av denne artikkelen]
(2007).
THE MOBILE CHROMOSOMAL REPEAT ELEMENT BCR1 IN BACILLUS CEREUS, B. THURINGIENSIS AND B. ANTHRACIS.
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Kristoffersen, Simen Martens; Ravnum, Solveig; Tourasse, Nicolas; Økstad, Ole Andreas Løchen; Kolstø, Anne-Brit & Davies, William
(2007).
Low concentrations of bile salts induce stress responses and reduce motility in the Bacillus cereus type strain.
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Fægri, Karoline; Ravnum, Solveig; Økstad, Ole Andreas Løchen; Tourasse, Nicolas & Kolstø, Anne-Brit
(2007).
Bruk av mikromatriser for å studere genregulering i Bacillus cereus.
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Økstad, Ole Andreas Løchen
(2006).
Infeksjonssykdommenes retur - hva kan genomforskning på patogene bakterier fortelle oss?
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Økstad, Ole Andreas Løchen; Tourasse, Nicolas; Rasko, David A; Meisal, Roger; Helgason, Erlendur & Kolstø, Anne-Brit
[Vis alle 8 forfattere av denne artikkelen]
(2006).
Gene discovery by comparative genome hybridization (GDCGH) − investigating gene diversity in the Bacillus cereus group of bacterial pathogens.
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Fægri, Karoline; Ravnum, Solveig; Økstad, Ole Andreas Løchen; Tourasse, Nicolas & Kolstø, Anne-Brit
(2006).
Comparing wt Bacillus cereus with a transcriptional regulator mutant.
Vis sammendrag
PlcR is a pleiotropic transcriptional regulator found in Bacillus cereus, an opportunistic pathogen, and Bacillus thuringiensis, an insect pathogen. The PlcR regulator has been shown to positively control a wide range of virulence factors that are exported to the extracellular environment, including a multitude of degradative enzymes, hemolysins, enterotoxins, phospholipases.
We have used microarrays to perform genomewide comparisons of gene expression in B. cereus ATCC 14579 (type strain) against a plcR deletion mutant to find genes that are regulated, directly or indirectly, by PlcR. In addition to confirming the results of earlier studies, we identify several new genes regulated by PlcR, including genes involved in motility, additional degradative enzymes, and prophage-related genes. Some of these genes carry an upstream regulatory PlcR-box and may thus be directly regulated. We also observe a considerable number of genes that may be subject to indirect regulation, and the mutation seems to influence central metabolic pathways involved in energy metabolism and lipid biosynthesis.
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Klevan, Leif Are; Tourasse, Nicolas; Stabell, Fredrik Bernhard; Kolstø, Anne-Brit & Økstad, Ole Andreas Løchen
(2006).
An evolutionary snapshot of the repeated element bcr1 in Bacillus cereus group strains close to the Bacillus anthracis cluster − transcription analysis, RNA folding, and traces of mobility.
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Tourasse, Nicolas; Helgason, Erlendur; Økstad, Ole Andreas Løchen & Kolstø, Anne-Brit
(2006).
Novel aspects of population and genome dynamics in the Bacillus cereus group of bacterial pathogens.
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Klevan, Are; Tourasse, Nicolas; Stabell, Fredrik Bernhard; Helgason, Erlendur; Kolstø, Anne-Brit & Økstad, Ole Andreas Løchen
(2006).
Genome dynamics in Bacillus cereus group pathogens - in silico experiments predict mobility of the bcr1 repeat element is related to RNA secondary structure stability.
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Tourasse, Nicolas; Helgason, Erlendur; Økstad, Ole Andreas Løchen & Kolstø, Anne-Brit
(2006).
The Bacillus cereus group: novel aspects of population structure and genome dynamics.
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Fægri, Karoline; Ravnum, Solveig; Økstad, Ole Andreas Løchen; Tourasse, Nicolas & Kolstø, Anne-Brit
(2006).
Comparative analysis of global gene expression in Bacillus cereus ATCC 14579 and a derivative strain following gene deletion of delta-PlcR, a transcriptional regulator of extracellular virulence.
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Kristoffersen, Simen Martens; Ravnum, Solveig; Økstad, Ole Andreas Løchen; Kolstø, Anne-Brit & Davies, William
(2006).
Transcriptome analysis of bile salt treated Bacillus cereus ATCC 14579.
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Biørnstad, Truls Johan; Kolstø, Anne-Brit & Økstad, Ole Andreas Løchen
(2006).
Screening for biofilm formation among bacteria from the Bacillus cereus group.
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Biørnstad, Truls Johan; Jensen, Christine; Gohar, Michel; Kolstø, Anne-Brit & Økstad, Ole Andreas Løchen
(2006).
Screening for biofilm formation among bacteria from the Bacillus cereus group and dissection of candidate genes potentially involved in the process.
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Klevan, Leif Are; Tourasse, Nicolas; Helgason, Erlendur; Økstad, Ole Andreas Løchen & Kolstø, Anne-Brit
(2005).
Repeated element bcr1 from the Bacillus cereus group: Distribution, evolution and possible mobility in a set of strains closely related to B. anthracis.
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Klevan, Leif Are; Tourasse, Nicolas; Helgason, Erlendur; Økstad, Ole Andreas Løchen & Kolstø, Anne-Brit
(2005).
The repeated element bcr1: Distribution, evolution and possible mobility in the Bacillus cereus group of bacteria.
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Klevan, Leif Are; Tourasse, Nicolas; Helgason, Erlendur; Økstad, Ole Andreas Løchen & Kolstø, Anne-Brit
(2005).
Distribution, evolution and possible mobility of the repeated element bcr1 by examination of Bacillus cereus group strains from the B. anthracis cluster.
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Klevan, Leif Are; Tourasse, Nicolas; Stabell, Fredrik Bernhard; Helgason, Erlendur; Kolstø, Anne-Brit & Økstad, Ole Andreas Løchen
(2005).
Exploring the phylogeny of Bacillus cereus strains close to the B. anthracis cluster through distribution and sequence analysis of the repeated element bcr1.
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Økstad, Ole Andreas Løchen
(2004).
Hva skiller en vanlig matforgiftningsbakterie fra en akutt dødelig bakterie - djevelen er i detaljene.
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Økstad, Ole Andreas Løchen; Tourasse, Nicolas; Stabell, Fredrik Bernhard; Sundfær, Cathrine Kleven; Klevan, Are & Risøen, Per Arne
[Vis alle 8 forfattere av denne artikkelen]
(2004).
bcr1, a novel mobile element specific to the Bacillus cereus group?
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Økstad, Ole Andreas Løchen; Tourasse, Nicolas; Stabell, Fredrik Bernhard; Sundfær, Cathrine Kleven; Klevan, Are & Risøen, Per Arne
[Vis alle 8 forfattere av denne artikkelen]
(2004).
Comparative genome analysis of pathogenic Bacilli – the bcr1 DNA repeat is specific to the Bacillus cereus group and exhibits mobile lement characteristics.
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Økstad, Ole Andreas Løchen; Helgason, Erlendur; Tourasse, Nicolas & Kolstø, Anne-Brit
(2004).
Whole genome sequencing reveals unexpected similarities between a Bacillus cereus dairy isolate and highly virulent Bacillus anthracis, the cause of anthrax.
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Økstad, Ole Andreas Løchen
(2003).
The Bacillus cereus group of bacteria � the good, the bad, and the ugly.
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Økstad, Ole Andreas Løchen
(2003).
Bacillus anthracis og miltbrann.
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Stenmark, Harald Alfred; Tourasse, Nicolas; Økstad, Ole Andreas Løchen; Helgason, Erlendur & Kolstø, Anne-Brit
(2003).
Norsk forskningsgruppe deltar i avsløring av miltbrannbakteriens hemmeligheter.
NBS-nytt.
ISSN 0801-3535.
s. 6–6.