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Hörstedt, Per
Publications (8 of 8) Show all publications
Pietra, S., Gustavsson, A., Kiefer, C., Kalmbach, L., Hörstedt, P., Ikeda, Y., . . . Grebe, M. (2013). Arabidopsis SABRE and CLASP interact to stabilize cell division plane orientation and planar polarity. Nature Communications, 4, 2779
Open this publication in new window or tab >>Arabidopsis SABRE and CLASP interact to stabilize cell division plane orientation and planar polarity
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2013 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 4, p. 2779-Article in journal (Refereed) Published
Abstract [en]

The orientation of cell division and the coordination of cell polarity within the plane of the tissue layer (planar polarity) contribute to shape diverse multicellular organisms. The root of Arabidopsis thaliana displays regularly oriented cell divisions, cell elongation and planar polarity providing a plant model system to study these processes. Here we report that the SABRE protein, which shares similarity with proteins of unknown function throughout eukaryotes, has important roles in orienting cell division and planar polarity. SABRE localizes at the plasma membrane, endomembranes, mitotic spindle and cell plate. SABRE stabilizes the orientation of CLASP-labelled preprophase band microtubules predicting the cell division plane, and of cortical microtubules driving cell elongation. During planar polarity establishment, sabre is epistatic to clasp at directing polar membrane domains of Rho-of-plant GTPases. Our findings mechanistically link SABRE to CLASP-dependent microtubule organization, shedding new light on the function of SABRE-related proteins in eukaryotes.

Place, publisher, year, edition, pages
Nature Publishing Group, 2013
National Category
Botany
Identifiers
urn:nbn:se:umu:diva-85312 (URN)10.1038/ncomms3779 (DOI)000328023900017 ()
Funder
Swedish Research Council, 2006-522, 2009-4846Knut and Alice Wallenberg Foundation
Available from: 2014-02-05 Created: 2014-01-31 Last updated: 2018-06-08Bibliographically approved
Hedberg, M. E., Moore, E. R., Svensson-Stadler, L., Hörstedt, P., Baranov, V., Hernell, O., . . . Hammarström, M.-L. (2012). Lachnoanaerobaculum a new genus in Lachnospiraceae; characterization of Lachnoanaerobaculum umeaense gen. nov., sp. nov., isolated from human small intestine, Lachnoanaerobaculum orale gen. nov., sp. nov., isolated from saliva and reclassification of Eubacterium saburreum (Prevot) Holdeman and Moore 1970 as Lachnoanaerobaculum saburreum comb. nov.. International Journal of Systematic and Evolutionary Microbiology, 62(11), 2685-2690
Open this publication in new window or tab >>Lachnoanaerobaculum a new genus in Lachnospiraceae; characterization of Lachnoanaerobaculum umeaense gen. nov., sp. nov., isolated from human small intestine, Lachnoanaerobaculum orale gen. nov., sp. nov., isolated from saliva and reclassification of Eubacterium saburreum (Prevot) Holdeman and Moore 1970 as Lachnoanaerobaculum saburreum comb. nov.
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2012 (English)In: International Journal of Systematic and Evolutionary Microbiology, ISSN 1466-5026, E-ISSN 1466-5034, Vol. 62, no 11, p. 2685-2690Article in journal (Refereed) Published
Abstract [en]

Two new obligately anaerobic Gram-positive, saccharolytic and non-proteolytic spore-forming bacilli (strain CD3:22 and N1) are described. Strain CD3:22 was isolated from a biopsy of the small intestine of a child with celiac disease and strain N1 from the saliva of a healthy young man. The cells of both strains were observed to be filamentous with lengths of approximately 5 to >20 µm, some of them curving and with swellings. The novel organisms produced H2S, NH3, butyric acid and acetic acid as major metabolic end products. Phylogenetic analyses, based on comparative 16S rRNA gene sequencing, revealed close relationships (98 % sequence similarity) between the two isolates, as well as the type strain of Eubacterium saburreum CCUG 28089T and four other Lachnospiraceae bacterium/E. saburreum-like organisms. This group of bacteria were clearly different from any of the 19 known genera in the family Lachnospiraceae. While Eubacterium spp. are reported to be non-spore-forming, reanalysis of E. saburreum CCUG 28089T confirmed that the bacterium, indeed, is able to form spores. Based on 16S rRNA gene sequencing, phenotypic and biochemical properties, CD3:22 (CCUG 58757T) and N1 (CCUG 60305T) represent new species of a new and distinct genus, named Lachnoanaerobaculum, in the family Lachnospiraceae [within the order Clostridiales, class Clostridia, phylum Firmicutes]. Strain CD3:22 is the type strain of the type species, Lachnoanaerobaculum umeaense gen. nov., sp. nov., of the proposed new genus. Strain N1 is the type strain of the species, Lachnoanaerobaculum orale gen. nov., sp. nov. Moreover, E. saburreum CCUG 28089T is reclassified as Lachnoanaerobaculum saburreum comb. nov.

National Category
Microbiology
Identifiers
urn:nbn:se:umu:diva-51168 (URN)10.1099/ijs.0.033613-0 (DOI)22228654 (PubMedID)
Funder
EU, FP7, Seventh Framework Programme, 222720Swedish Research Council
Available from: 2012-01-11 Created: 2012-01-11 Last updated: 2018-06-08Bibliographically approved
Ou, G., Hedberg, M., Hörstedt, P., Baranov, V., Forsberg, G., Drobni, M., . . . Hammarström, S. (2009). Proximal small intestinal microbiota and identification of rod-shaped bacteria associated with childhood celiac disease. American Journal of Gastroenterology, 104(12), 3058-3067
Open this publication in new window or tab >>Proximal small intestinal microbiota and identification of rod-shaped bacteria associated with childhood celiac disease
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2009 (English)In: American Journal of Gastroenterology, ISSN 0002-9270, E-ISSN 1572-0241, Vol. 104, no 12, p. 3058-3067Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES: Alterations in the composition of the microbiota in the intestine may promote development of celiac disease (CD). Using scanning electron microscopy (SEM) we previously demonstrated that rod-shaped bacteria were present on the epithelium of proximal small intestine in children with CD but not in controls. In this study we characterize the microbiota of proximal small intestine in children with CD and controls and identify CD-associated rod-shaped bacteria. METHODS: Proximal small intestine biopsies from 45 children with CD and 18 clinical controls were studied. Bacteria were identified by 16S rDNA sequencing in DNA extracted from biopsies washed with buffer containing dithiothreitol to enrich bacteria adhering to the epithelial lining, by culture-based methods and by SEM and transmission electron microscopy. RESULTS: The normal, mucosa-associated microbiota of proximal small intestine was limited. It was dominated by the genera Streptococcus and Neisseria, and also contained Veillonella, Gemella, Actinomyces, Rothia, and Haemophilus. The proximal small intestine microbiota in biopsies from CD patients collected during 2004-2007 differed only marginally from that of controls, and only one biopsy (4%) had rod-shaped bacteria by SEM (SEM+). In nine frozen SEM+ CD biopsies from the previous study, microbiotas were significantly enriched in Clostridium, Prevotella, and Actinomyces compared with SEM- biopsies. Bacteria of all three genera were isolated from children born during the Swedish CD epidemic. New Clostridium and Prevotella species and Actinomyces graevenitzii were tentatively identified. CONCLUSIONS: Rod-shaped bacteria, probably of the indicated species, constituted a significant fraction of the proximal small intestine microbiota in children born during the Swedish CD epidemic and may have been an important risk factor for CD contributing to the fourfold increase in disease incidence in children below 2 years of age during that time.

Keywords
small intestinal microbiota, identification of rod-shaped bacteria, childhood celiac disease
National Category
Gastroenterology and Hepatology
Identifiers
urn:nbn:se:umu:diva-35059 (URN)10.1038/ajg.2009.524 (DOI)19755974 (PubMedID)
Available from: 2010-07-05 Created: 2010-07-05 Last updated: 2018-06-08Bibliographically approved
Janson, V., Behnam-Motlagh, P., Henriksson, R., Hörstedt, P., Engström, K. G. & Grankvist, K. (2008). Phase-contrast microscopy studies of early Cisplatin-induced morphological changes of malignant mesothelioma cells and the correspondence to induced apoptosis. Experimental Lung Research, 34(2), 49-67
Open this publication in new window or tab >>Phase-contrast microscopy studies of early Cisplatin-induced morphological changes of malignant mesothelioma cells and the correspondence to induced apoptosis
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2008 (English)In: Experimental Lung Research, ISSN 0190-2148, E-ISSN 1521-0499, Vol. 34, no 2, p. 49-67Article in journal (Refereed) Published
Abstract [en]

Cisplatin treatment efficacy of malignant pleural mesothelioma (MPM) is aggravated by resistance and adverse effects. In P31 MPM cells, cisplatin induces morphological changes and apoptosis. To determine if very early (10 minutes) morphological responses corresponded to apoptosis-induction, cisplatin effects on P31 morphology were examined with phase-contrast microscopy (PCM), scanning electron microscopy (SEM), and flow cytometry (fluorescence-activated cell sorting [FACS]), and compared to apoptosis-induction over time. Increased membrane protrusions were identified with PCM and SEM, but these were not consistent with the induction of apoptosis. The authors concluded that very early morphological changes can be determined with PCM in MPM, but they did not convincingly correspond to apoptosis induction.

Place, publisher, year, edition, pages
Taylor & Francis, 2008
Keywords
apoptosis, cisplatin, malignant pleural mesothelioma (MPM), phase-contrast microscopy (PCM), scanning electron microscopy (SEM)
National Category
Cancer and Oncology Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-8814 (URN)10.1080/01902140701884398 (DOI)000253086700001 ()18266129 (PubMedID)
Available from: 2008-02-14 Created: 2008-02-14 Last updated: 2019-08-06Bibliographically approved
Sunnegårdh-Grönberg, K., Dijken, J. W. V., Lindberg, A. & Hörstedt, P. (2004). Interfacial adaptation of a calcium aluminate cement used in class II cavities, in vivo. Clinical Oral Investigations, 8(2), 75-80
Open this publication in new window or tab >>Interfacial adaptation of a calcium aluminate cement used in class II cavities, in vivo
2004 (English)In: Clinical Oral Investigations, ISSN 1432-6981, E-ISSN 1436-3771, Vol. 8, no 2, p. 75-80Article in journal (Refereed) Published
Abstract [en]

The aim of this in vivo study was to evaluate the interfacial marginal adaptation of a calcium aluminate cement, Doxadent (DD), and to compare it intra-individually with a resin composite, Tetric Ceram/Syntac Single-Component (TC/SS), in Class II cavities. Sixteen Class II box-shaped, enamel-bordered cavities were prepared in eight premolars scheduled to be extracted after 1 month's service for orthodontic reasons. The interfacial marginal adaptation (internal surfaces) of the restorations was evaluated by a quantitative scanning electron microscope analysis using a replica method. DD showed a statistically significant, lower degree of gap-free adaptation to enamel compared with TC/SS: 84% vs. 93%. To dentin, DD showed a significantly better adaptation than TC/SS: 72% vs. 49%. A high frequency of enamel fractures perpendicular to the margins was observed for the DD restorations, which may be explained by an expansion of the calcium-aluminate cement. It can be concluded that DD showed a better adaptation to dentin while TC/SS showed a better adaptation to enamel. The dimensional changes of DD have to be investigated before clinical use can be recommended.

Place, publisher, year, edition, pages
Springer-Verlag, 2004
Keywords
Clinical, Dental restoration, Dental cement, Interfacial adaptation
Identifiers
urn:nbn:se:umu:diva-17140 (URN)10.1007/s00784-003-0242-3 (DOI)14661081 (PubMedID)
Available from: 2007-11-02 Created: 2007-11-02 Last updated: 2018-06-09Bibliographically approved
Forsberg, G., Fahlgren, A., Hörstedt, P., Hammarström, S., Hernell, O. & Hammarström, M.-L. (2004). Presence of bacteria and innate immunity of intestinal epithelium in childhood celiac disease. American Journal of Gastroenterology, 99(5), 894-904
Open this publication in new window or tab >>Presence of bacteria and innate immunity of intestinal epithelium in childhood celiac disease
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2004 (English)In: American Journal of Gastroenterology, ISSN 0002-9270, E-ISSN 1572-0241, Vol. 99, no 5, p. 894-904Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES: Exposure to gliadin and related prolamins and appropriate HLA-DQ haplotype are necessary but not sufficient for contracting celiac disease (CD). Aberrant innate immune reactions could be contributing risk factors. Therefore, jejunal biopsies were screened for bacteria and the innate immune status of the epithelium investigated.

METHODS: Children with untreated, treated, challenged CD, and controls were analyzed. Bacteria were identified by scanning electron microscopy. Glycocalyx composition and mucin and antimicrobial peptide production were studied by quantitative RT-PCR, antibody and lectin immunohistochemistry.

RESULTS: Rod-shaped bacteria were frequently associated with the mucosa of CD patients, with both active and inactive disease, but not with controls. The lectin Ulex europaeus agglutinin I (UEAI) stained goblet cells in the mucosa of all CD patients but not of controls. The lectin peanut agglutinin (PNA) stained glycocalyx of controls but not of CD patients. mRNA levels of mucin-2 (MUC2), alpha-defensins HD-5 and HD-6, and lysozyme were significantly increased in active CD and returned to normal in treated CD. Their expression levels correlated to the interferon-gamma mRNA levels in intraepithelial lymphocytes. MUC2, HD-5, and lysozyme proteins were seen in absorptive epithelial cells. beta-defensins hBD-1 and hBD-2, carcinoembryonic antigen (CEA), CEA cell adhesion molecule-1a (CEACAM1a), and MUC3 were not affected.

CONCLUSIONS: Unique carbohydrate structures of the glycocalyx/mucous layer are likely discriminating features of CD patients. These glycosylation differences could facilitate bacterial adhesion. Ectopic production of MUC2, HD-5, and lysozyme in active CD is compatible with goblet and Paneth cell metaplasia induced by high interferon-gamma production by intraepithelial lymphocytes.

National Category
Gastroenterology and Hepatology
Identifiers
urn:nbn:se:umu:diva-21221 (URN)10.1111/j.1572-0241.2004.04157.x (DOI)15128357 (PubMedID)
Available from: 2009-04-07 Created: 2009-04-07 Last updated: 2018-06-09Bibliographically approved
Milton, D. L., O'Toole, R., Hörstedt, P. & Wolf-Watz, H. (1996). Flagellin A is essential for the virulence of Vibrio anguillarum. Journal of Bacteriology, 178(5), 1310-1319
Open this publication in new window or tab >>Flagellin A is essential for the virulence of Vibrio anguillarum
1996 (English)In: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 178, no 5, p. 1310-1319Article in journal (Refereed) Published
Abstract [en]

A flagellin gene from the fish pathogen Vibrio anguillarum was cloned, sequenced, and mutagenized. The DNA sequence suggests that the flaA gene encodes a 40.1-kDa protein and is a single transcriptional unit. A polar mutation and four in-frame deletion mutations (180 bp deleted from the 5' end of the gene, 153 bp deleted from the 3' end of the gene, a double deletion of both the 180- and 153-bp deletions, and 942 bp deleted from the entire gene) were made. Compared with the wild type, all mutants were partially motile, and a shortening of the flagellum was seen by electron microscopy. Wild-type phenotypes were regained when the mutations were transcomplemented with the flaA gene. Protein analysis indicated that the flaA gene corresponds to a 40-kDa protein and that the flagellum consists of three additional flagellin proteins with molecular masses of 41, 42, and 45 kDa. N-terminal sequence analysis confirmed that the additional proteins were flagellins with N termini that are 82 to 88% identical to the N terminus of FlaA. Virulence studies showed that the N terminal deletion, the double deletion, and the 942-bp deletion increased the 50% lethal dose between 70- and 700-fold via immersion infection, whereas infection via intraperitoneal injection showed no loss in virulence. In contrast, the polar mutant and the carboxy-terminal deletion mutant showed approximately a 10(4)-fold increase in the 50% lethal dose by both immersion and intraperitoneal infection. In summary, FlaA is needed for crossing the fish integument and may play a role in virulence after invasion of the host.

National Category
Microbiology
Identifiers
urn:nbn:se:umu:diva-121653 (URN)8631707 (PubMedID)
Available from: 2016-06-03 Created: 2016-06-03 Last updated: 2018-06-07Bibliographically approved
McGee, K., Hörstedt, P. & Milton, D. L. (1996). Identification and characterization of additional flagellin genes from Vibrio anguillarum. Journal of Bacteriology, 178(17), 5188-5198
Open this publication in new window or tab >>Identification and characterization of additional flagellin genes from Vibrio anguillarum
1996 (English)In: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 178, no 17, p. 5188-5198Article in journal (Refereed) Published
Abstract [en]

Previously, the flagellar filament of Vibrio anguillarum was suggested to consist of flagellin A and three additional flagellin proteins, FlaB, -C, and -D. This study identifies the genes encoding FlaB, -C, and -D and a possible fifth flagellin gene that may encode FlaE. The flagellin genes map at two separate DNA loci and are most similar to the four polar flagellin genes of Vibrio parahaemolyticus, also located at two DNA loci. The genetic organization of these two loci is conserved between both organisms. For each gene, in-frame deletions of the entire gene, the 5' end, and the 3' end were made. Mutant analysis showed that each mutation, except those in flaE, caused a loss of flagellin from the filament. However, no obvious structural loss in the filament, as determined by electron microscopy, and only slight decreases in motility were seen. Virulence analysis indicated that all but two of the mutations gave a wild-type phenotype. The 5'-end deletions of flaD and flaE decreased virulence significantly (>10(4)-fold) of infections via both the intraperitoneal and immersion routes. These results indicate that, like FlaA, FlaD and FlaE may also be involved in virulence.

National Category
Microbiology
Identifiers
urn:nbn:se:umu:diva-121652 (URN)A1996VE37100019 ()8752337 (PubMedID)
Available from: 2016-06-03 Created: 2016-06-03 Last updated: 2018-06-07Bibliographically approved
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