| 1. |
- Andersson, Ida E, 1982-, et al.
(författare)
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Design of glycopeptides used to investigate class II MHC binding and T-Cell responses associated with autoimmune arthritis
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 6:3, s. e17881-
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Tidskriftsartikel (refereegranskat)abstract
- The glycopeptide fragment CII259–273 from type II collagen (CII) binds to the murine Aq and human DR4 class II Major Histocompatibility Complex (MHC II) proteins, which are associated with development of murine collagen-induced arthritis (CIA) and rheumatoid arthritis (RA), respectively. It has been shown that CII259–273 can be used in therapeutic vaccination of CIA. This glycopeptide also elicits responses from T-cells obtained from RA patients, which indicates that it has an important role in RA as well. We now present a methodology for studies of (glyco)peptide-receptor interactions based on a combination of structure-based virtual screening, ligand-based statistical molecular design and biological evaluations. This methodology included the design of a CII259–273 glycopeptide library in which two anchor positions crucial for binding in pockets of Aq and DR4 were varied. Synthesis and biological evaluation of the designed glycopeptides provided novel structure-activity relationship (SAR) understanding of binding to Aq and DR4. Glycopeptides that retained high affinities for these MHC II proteins and induced strong responses in panels of T-cell hybridomas were also identified. An analysis of all the responses revealed groups of glycopeptides with different response patterns that are of high interest for vaccination studies in CIA. Moreover, the SAR understanding obtained in this study provides a platform for the design of second-generation glycopeptides with tuned MHC affinities and T-cell responses.
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| 2. |
- Andersson, Ida E., 1982-, et al.
(författare)
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(E)-Alkene and Ethylene Isosteres Substantially Alter the Hydrogen-Bonding Network in Class II MHC Aq/Glycopeptide Complexes and Affect T-Cell Recognition
- 2011
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society. - 0002-7863 .- 1520-5126. ; 133:36, s. 14368-14378
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Tidskriftsartikel (refereegranskat)abstract
- The structural basis for antigen presentation by class II major histocompatibility complex (MHC) proteins to CD4(+) T-cells is important for understanding and possibly treating autoimmune diseases. In the work described in this paper, (E)-alkene and ethylene amide-bond isosteres were used to investigate the effect of removing hydrogen-bonding possibilities from the CII259-270 glycopeptide, which is bound by the arthritis-associated murine A(q) class II MHC protein. The isostere-modified glycopeptides showed varying and unexpectedly large losses of A(q) binding that could be linked to the dynamics of the system. Molecular dynamics (MD) simulations revealed that the backbone of CII259-270 and the A(q) protein are able to form up to 11 hydrogen bonds, but fewer than this number are present at any one time. Most of the strong hydrogen-bond interactions were formed by the N-terminal part of the glycopeptide, i.e., in the region where the isosteric replacements were made. The structural dynamics also revealed that hydrogen bonds were strongly coupled to each other; the loss of one hydrogen-bond interaction had a profound effect on the entire hydrogen-bonding network. The A(q) binding data revealed that an ethylene isostere glycopeptide unexpectedly bound more strongly to A(q) than the corresponding (E)-alkene, which is in contrast to the trend observed for the other isosteres. Analysis of the MD trajectories revealed that the complex conformation of this ethylene isostere was structurally different and had an altered molecular interaction pattern compared to the other A(q)/glycopeptide complexes. The introduced amide-bond isosteres also affected the interactions of the glycopeptide/A(q) complexes with T-cell receptors. The dynamic variation of the patterns and strengths of the hydrogen-bond interactions in the class II MHC system is of critical importance for the class II MHC/peptide/TCR signaling system.
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| 3. |
- Andersson, Ida E., 1982-, et al.
(författare)
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Oxazole-modified glycopeptides that target arthritis-associated class II MHC Aq and DR4 proteins
- 2010
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Ingår i: Organic and biomolecular chemistry. - : RSC Publishing. - 1477-0520 .- 1477-0539. ; 8:13, s. 2931-2940
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Tidskriftsartikel (refereegranskat)abstract
- The glycopeptide CII259-273, a fragment from type II collagen (CII), can induce tolerance in mice susceptible to collagen-induced arthritis (CIA), which is a validated disease model for rheumatoid arthritis (RA). Here, we describe the design and synthesis of a small series of modified CII259-273 glycopeptides with oxazole heterocycles replacing three potentially labile peptide bonds. These glycopeptidomimetics were evaluated for binding to murine CIA-associated A(q) and human RA-associated DR4 class II major histocompatibility complex (MHC) proteins. The oxazole modifications drastically reduced or completely abolished binding to A(q). Two of the glycopeptidomimetics were, however, well tolerated in binding to DR4 and they also induced strong responses by one or two DR4-restricted T-cell hybridomas. This work contributes to the development of an altered glycopeptide for inducing immunological tolerance in CIA, with the long-term goal of developing a therapeutic vaccine for treatment of RA.
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| 4. |
- Andersson, Ida E., 1982-, et al.
(författare)
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Probing Molecular Interactions within Class II MHC A(q)/Glycopeptide/T-Cell Receptor Complexes Associated with Collagen-Induced Arthritis.
- 2007
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Ingår i: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 1520-4804 .- 0022-2623. ; 50:23, s. 5627-5643
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Tidskriftsartikel (refereegranskat)abstract
- T cells obtained in a mouse model for rheumatoid arthritis are activated by a glycopeptide fragment from rat type II collagen (CII) bound to the class II major histocompatibility complex A(q) molecule. We report a comparative model of A(q) in complex with the glycopeptide CII260-267. This model was used in a structure-based design approach where the amide bond between Ala(261) and Gly(262) in the glycopeptide was selected for replacement with psi[COCH2], psi[CH2NH2+], and psi[(E)-CH=CH] isosteres. Ala-Gly isostere building blocks were then synthesized and introduced in CII260-267 and CII259-273 glycopeptides. The modified glycopeptides were evaluated for binding to the A(q) molecule, and the results were interpreted in view of the A(q)/glycopeptide model. Moreover, recognition by a panel of T-cell hybridomas revealed high sensitivity for the backbone modifications. These studies contribute to the understanding of the interactions in the ternary A(q)/glycopeptide/T-cell receptor complexes that activate T cells in autoimmune arthritis and suggest possibilities for new vaccination approaches.
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| 5. |
- Dzhambazov, Balik, et al.
(författare)
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In vitro screening for antitumour activity of Clinopodium vulgare L. (Lamiaceae) extracts.
- 2002
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Ingår i: Biological and Pharmaceutical Bulletin. - : Pharmaceutical Society of Japan. - 0918-6158 .- 1347-5215. ; 25:4, s. 499-504
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Tidskriftsartikel (refereegranskat)abstract
- Aqueous extract of Clinopodium vulgare L. showed strong antitumour activity when tested in vitro on A2058 (human metastatic melanoma), HEp-2 (epidermoid carcinoma, larynx, human) and L5178Y (mouse lymphoma) cell lines-6 h after treatment disintegration of the nuclei and cell lysis started. Applied at a concentration of 80 microg/ml it reduced the cell survival to 1.0, 5.6 and 6.6%, respectively. The concentrations of aqueous extract inhibiting the growth of A2058, HEp-2 and L5178Y cells by 50% (IC50 values) were calculated to be 20, 10 and 17.8 microg/ml respectively. Two groups of active substances were detected: the first one, probably combining glycosides, influenced adhesion, while the second one caused massive cell vacuolisation. The chloroform extract, which contained ursolic acid and gentriacontan had also cytotoxic, however a little bit weaker effect. All changes observed were irreversible.
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| 6. |
- Dzhambazov, Balik, et al.
(författare)
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Karyotypic analysis of two algae species Scenedesmus incrassatulus Bohl and Scenedesmus antennatus Bréb (Chlorophyta, Chlorococcales).
- 2003
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Ingår i: Hereditas. - : Springer Science and Business Media LLC. - 1601-5223 .- 0018-0661. ; 139:1, s. 35-40
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Tidskriftsartikel (refereegranskat)abstract
- The karyotypes (number, morphology and size of the chromosomes) of two algae species of Scenedesmus genus, S. incrassatulus and S. antennatus, were studied. The karyotype of S. incrassatulus (n=4) was asymmetric, characterized by two large metacentric, one large submetacentric and one small metacentric chromosomes. The karyotype assembly of S. antennatus (n=6) reveals two metacentrics and four submetacentrics. This karyotype was symmetric. The general chromosomal formulae of both species, as well as the total average metaphase length of their haploid set are presented. The results of chromosomal studies of other related species are compared and discussed. Data from the karyotypic analysis showed that S. incrassatulus, S. antennatus and S. obliquus are separate biological species from taxonomical point of view.
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| 7. |
- Dzhambazov, Balik, et al.
(författare)
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Karyotypic differences and evolutionary tendencies of some species from the subgenus Obliquodesmus Mlad. of genus Scenedesmus Meyen (Chlorophyta, Chlorococcales)
- 2006
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Ingår i: Journal of Genetics. - 0022-1333. ; 85:1, s. 39-44
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Tidskriftsartikel (refereegranskat)abstract
- Karyotype structures of Scenedesmus acuminatus (Lagerch.) Chod. and Scenedesmus pectinatus Meyen are compared. The karyotype of S. acuminatus (n = 5) is described for the first time. It reveals four large metacentric and one large submeta centric chromosomes (4M + 1SM). The established karyotype differences have been helpful in clarifying the taxonomic position of these two species. The cytological analyses of other related clonal cultures suggest an evolutionary transition from S. pectinatus towards S. regularis through S. pectinatus f. regularis, which correlates with the morphological data about their variability. These results are discussed from the cytogenetic, morphological and evolutionary point of view. On the basis of the karyotypic analysis, it was confirmed that from a taxonomic point of view S. pectinalus, S. acuminatus and S. regularis are separate biological species.
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| 8. |
- Dzhambazov, Balik, et al.
(författare)
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Morphological, genetic and functional variability of a T-cell hybridoma line.
- 2003
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Ingår i: Folia Biologica. - 0015-5500. ; 49:2, s. 87-94
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Tidskriftsartikel (refereegranskat)abstract
- The variability in the morphology, modal number of chromosomes, TCR expression and functional reactivity of a CII-specific T-cell hybridoma at continuous subcultivation have been investigated. As the number of passages increased, besides the oval semiadherent cells (normal phenotype), fibroblast-like cells (transformed phenotype) were also observed. The two cell subpopulations differed in their karyotype characteristic, as well as in their functional reactivity. The cell population with a normal phenotype was characterized by a tetramodal number of chromosomes (30, 40, 48 and 70) and trisomies of chromosomes 6 and 14, while the cell population with a transformed phenotype was characterized by a trimodal number of chromosomes (11, 68 and 74) and trisomy of chromosome 12. A nullisomy of sex chromosomes was established in both types of cells. In the initial passages of subcultivation, 73.04% of the cells with a normal morphological phenotype expressed TCR-CD3 complexes on their surface and possessed high functional reactivity. After a two-week subcultivation, the values of these indices went down considerably: 46.11% of the cells expressed functional TCR-CD3 complexes, as a result of which their functional reactivity decreased. Only 2.71% of the cells with a transformed morphological phenotype expressed functional TCR-CD3 complexes on their surface. In these cells, a total loss of reactivity towards the specific antigens was established. The achieved results show that at continuous subcultivation the T-cell hybridomas are unstable, and with the increase in the number of passages there appear chromosome rearrangements, leading to loss of their functional reactivity.
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| 9. |
- Dzhambazov, Balik, et al.
(författare)
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The major T cell epitope on type II collagen is glycosylated in normal cartilage but modified by arthritis in both rats and humans
- 2005
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Ingår i: European Journal of Immunology. - : Wiley. - 1521-4141 .- 0014-2980. ; 35:2, s. 357-366
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Tidskriftsartikel (refereegranskat)abstract
- Type II collagen (CII) is a target for autoreactive T cells in both rheumatoid arthritis and the murine model collagen-induced arthritis. The determinant core of CII has been identified as CII260-270, and the alteration of this T cell epitope by posttranslational modifications is known to be critical for development of arthritis in mice. Using CII-specific T cell hybridomas we have now shown that the immunodominant T cell epitope in the normal (healthy) human and rat joint cartilage is O-glycosylated at the critical T cell receptor recognition position 264 with a mono- or di-saccharide attached to a hydroxylysine. In contrast, in the arthritic human and rat joint cartilage there are both glycosylated and non-glycosylated CII forms. Glycosylated CII from normal cartilage could not be recognized by T cells reactive to peptides having only lysine or hydroxylysine at position 264, showing that antigen-presenting cells could not degrade the O-linked carbohydrate. Thus, the variable forms of the glycosylated epitope are determined by the structures present in cartilage, and these vary during the disease course. We conclude that the chondrocyte determines the structures presented to the immune system and that these structures are different in normal versus arthritic states.
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| 10. |
- Dzhambazov, Balik, et al.
(författare)
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The major T cell epitope on type II collagen is glycosylated in normal cartilage but modified by arthritis in both rats and humans
- 2005
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Ingår i: EUROPEAN JOURNAL OF IMMUNOLOGY. - : Wiley. - 0014-2980 .- 1521-4141. ; 35:2, s. 357-66
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Tidskriftsartikel (refereegranskat)abstract
- Type II collagen (CII) is a target for autoreactive T cells in both rheumatoid arthritis and the murine model collagen-induced arthritis. The determinant core of CII has been identified as CII260-270, and the alteration of this T cell epitope by posttranslational modifications is known to be critical for development of arthritis in mice. Using CII-specific T cell hybridomas we have now shown that the immunodominant T cell epitope in the normal (healthy) human and rat joint cartilage is O-glycosylated at the critical T cell receptor recognition position 264 with a mono- or di-saccharide attached to a hydroxylysine. In contrast, in the arthritic human and rat joint cartilage there are both glycosylated and non-glycosylated CII forms. Glycosylated CII from normal cartilage could not be recognized by T cells reactive to peptides having only lysine or hydroxylysine at position 264, showing that antigen-presenting cells could not degrade the O-linked carbohydrate. Thus, the variable forms of the glycosylated epitope are determined by the structures present in cartilage, and these vary during the disease course. We conclude that the chondrocyte determines the structures presented to the immune system and that these structures are different in normal versus arthritic states.
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| 11. |
- Dzhambazov, Balik, et al.
(författare)
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Therapeutic vaccination of active arthritis with a glycosylated collagen type II peptide in complex with MHC class II molecules
- 2006
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Ingår i: Journal of Immunology. - Rockville, MD : American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 176, s. 1525-33
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Tidskriftsartikel (refereegranskat)abstract
- In both collagen-induced arthritis (CIA) and rheumatoid arthritis, T cells recognize a galactosylated peptide from type II collagen (CII). In this study, we demonstrate that the CII259-273 peptide, galactosylated at lysine 264, in complex with Aq molecules prevented development of CIA in mice and ameliorated chronic relapsing disease. In contrast, nonglycosylated CII259-273/Aq complexes had no such effect. CIA dependent on other MHC class II molecules (Ar/Er) was also down-regulated, indicating a bystander vaccination effect. T cells could transfer the amelioration of CIA, showing that the protection is an active process. Thus, a complex between MHC class II molecules and a posttranslationally modified peptide offers a new possibility for treatment of chronically active autoimmune inflammation such as rheumatoid arthritis. © 2006 by The American Association of Immunologists, Inc.
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| 12. |
- Dzhambazov, Balik, et al.
(författare)
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Tissue transglutaminase enhances collagen type II-induced arthritis and modifies the immunodominant T-cell epitope CII260-270
- 2009
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Ingår i: European Journal of Immunology. - : Wiley. - 0014-2980 .- 1521-4141. ; 39:9, s. 2412-2423
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Tidskriftsartikel (refereegranskat)abstract
- The calcium-dependent enzyme tissue transglutaminase (tTG) is associated with diverse biological functions, such as induction of apoptosis, modeling of the extracellular matrix, receptor-mediated endocytosis, cell growth and differentiation, cell adhesion and signal transduction. Also, it may deamidate glutamine residues to glutamic acid and catalyze cross-linking of proteins. In this study, we have investigated the impact of tTG for posttranslational modifications and cross-linking of the immunodominant T-cell epitope CII260-270 and their effects on the collagen-induced arthritis, an animal model for rheumatoid arthritis. By using mass spectrometry analysis and hybridoma assays, we have demonstrated that tTG could perform both types of modifications (deamidation and cross-link formation) on the immunodominant T-cell epitope CII259-273. Replacement of the glutamine at position 267 with glutamic acid leads to a decreased binding affinity to MHC II. T cells recognized both non-modfied (Q(267)) and modified (E(267)) CII259-273-peptides. We also show that administration of tTG leads to increased incidence, severity and histopathological manifestations of collagen-induced arthritis in mice. Moreover, we conclude that both processes, deamidation and cross-linking, are involved in the tTG-catalyzed reactions, and in vivo administration of tTG enhances arthritis severity and joint destruction in mice.
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| 13. |
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| 14. |
- Holm, Lotta, et al.
(författare)
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Quantitative Structure-Activity Relationship of Peptides Binding to the Class II Major Histocompatibility Complex Molecule A(q) Associated with Autoimmune Arthritis.
- 2007
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Ingår i: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 1520-4804 .- 0022-2623. ; 50:9, s. 2049-2059
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Tidskriftsartikel (refereegranskat)abstract
- Presentation of (glyco)peptides by the class II major histocompatibility complex molecule Aq to T cells plays a central role in collagen-induced arthritis, an animal model for the autoimmune disease rheumatoid arthritis. A peptide library was designed using statistical molecular design in amino acid space in which five positions in the minimal mouse collagen type II binding epitope CII260-267 were varied. A substantially reduced peptide library of 24 peptides with diverse and representative molecular characteristics was selected, synthesized, and evaluated for the binding strength to Aq. A multivariate QSAR model was established by correlating calculated descriptors, compressed to its principle properties, with the binding data using partial least-square regression. The model was successfully validated by an external test set. Interpretation of the model provided a molecular property binding motif for peptides interacting with Aq. The information may be useful in future research directed toward new treatments of rheumatoid arthritis.
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| 15. |
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| 16. |
- Lavasani, Shahram, et al.
(författare)
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A novel probiotic mixture exerts a therapeutic effect on experimental autoimmune encephalomyelitis mediated by IL-10 producing regulatory T cells.
- 2010
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 5:2
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease of the central nervous system (CNS). One potential therapeutic strategy for MS is to induce regulatory cells that mediate immunological tolerance. Probiotics, including lactobacilli, are known to induce immunomodulatory activity with promising effects in inflammatory diseases. We tested the potential of various strains of lactobacilli for suppression of experimental autoimmune encephalomyelitis (EAE), an animal model of MS. METHODOLOGY/PRINCIPAL FINDINGS: The preventive effects of five daily-administered strains of lactobacilli were investigated in mice developing EAE. After a primary screening, three Lactobacillus strains, L. paracasei DSM 13434, L. plantarum DSM 15312 and DSM 15313 that reduced inflammation in CNS and autoreactive T cell responses were chosen. L. paracasei and L. plantarum DSM 15312 induced CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) in mesenteric lymph nodes (MLNs) and enhanced production of serum TGF-beta1, while L. plantarum DSM 15313 increased serum IL-27 levels. Further screening of the chosen strains showed that each monostrain probiotic failed to be therapeutic in diseased mice, while a mixture of the three lactobacilli strains suppressed the progression and reversed the clinical and histological signs of EAE. The suppressive activity correlated with attenuation of pro-inflammatory Th1 and Th17 cytokines followed by IL-10 induction in MLNs, spleen and blood. Additional adoptive transfer studies demonstrated that IL-10 producing CD4(+)CD25(+) Tregs are involved in the suppressive effect induced by the lactobacilli mixture. CONCLUSIONS/SIGNIFICANCE: Our data provide evidence showing that the therapeutic effect of the chosen mixture of probiotic lactobacilli was associated with induction of transferable tolerogenic Tregs in MLNs, but also in the periphery and the CNS, mediated through an IL-10-dependent mechanism. Our findings indicate a therapeutic potential of oral administration of a combination of probiotics and provide a more complete understanding of the host-commensal interactions that contribute to beneficial effects in autoimmune diseases.
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| 17. |
- Lavasani, Shahram, et al.
(författare)
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Monoclonal Antibody against T-Cell Receptor alphabeta Induces Self-Tolerance in Chronic Experimental Autoimmune Encephalomyelitis.
- 2007
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Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 1365-3083 .- 0300-9475. ; 65:1, s. 39-47
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Tidskriftsartikel (refereegranskat)abstract
- The therapeutic effect of monoclonal antibody (H57-597 MoAb) against T-cell receptor (TCR) alpha beta has been investigated on MOG(35-55)-induced experimental autoimmune encephalomyelitis (EAE), as a model system for T-cell-mediated chronic inflammation in the central nervous system (CNS). Short-term administration of the anti-TCR alpha beta immediately after immunization protected the mice from EAE. Furthermore, anti-TCR alpha beta treatment on an established disease restored the self-tolerance which led to a complete remission of EAE and a dramatic reduction of inflammatory cells in the CNS, while treatment with control antibody (hamster IgG) was ineffective. The remission was durable and not associated with disappearance of autoreactive T cells as measured by persistence of MOG-reactive T-cell proliferation in vitro. However, MOG-reactive T cells from anti-TCR-treated animals produced significantly lower amounts of inflammatory TNF-alpha and IFN-gamma. In addition, while a transient deletion of CD4(+) and CD8(+) T cells was observed, a population of T cells expressing CD3, NK1.1 and CD69 (NKT cells) were expanding. By transfer of spleen cells from anti-TCR MoAb-treated animals, we could show that the tolerogenic capacity can be transferred to untreated recipients with EAE. The data indicate therapeutic effect of anti-TCR alpha beta MoAb (H57-597), which represents a promising approach in treatment of T-cell-mediated autoimmune diseases.
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| 18. |
- Merky, Patrick, et al.
(författare)
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Visualization and phenotyping of proinflammatory antigen-specific T cells during collagen-induced arthritis in a mouse with a fixed collagen type II-specific transgenic T-cell receptor beta-chain
- 2010
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Ingår i: Arthritis Research and Therapy. - : Springer Science and Business Media LLC. - 1478-6362 .- 1478-6354. ; 12:4
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The V beta 12-transgenic mouse was previously generated to investigate the role of antigen-specific T cells in collagen-induced arthritis (CIA), an animal model for rheumatoid arthritis. This mouse expresses a transgenic collagen type II (CII)-specific T-cell receptor (TCR) beta-chain and consequently displays an increased immunity to CII and increased susceptibility to CIA. However, while the transgenic V beta 12 chain recombines with endogenous alpha-chains, the frequency and distribution of CII-specific T cells in the V beta 12-transgenic mouse has not been determined. The aim of the present report was to establish a system enabling identification of CII-specific T cells in the V beta 12-transgenic mouse in order to determine to what extent the transgenic expression of the CII-specific beta-chain would skew the response towards the immunodominant galactosylated T-cell epitope and to use this system to monitor these cells throughout development of CIA. Methods: We have generated and thoroughly characterized a clonotypic antibody, which recognizes a TCR specific for the galactosylated CII(260-270) peptide in the V beta 12-transgenic mouse. Hereby, CII-specific T cells could be quantified and followed throughout development of CIA, and their phenotype was determined by combinatorial analysis with the early activation marker CD154 (CD40L) and production of cytokines. Results: The V beta 12-transgenic mouse expresses several related but distinct T-cell clones specific for the galactosylated CII peptide. The clonotypic antibody could specifically recognize the majority (80%) of these. Clonotypic T cells occurred at low levels in the naive mouse, but rapidly expanded to around 4% of the CD4(+) T cells, whereupon the frequency declined with developing disease. Analysis of the cytokine profile revealed an early Th1-biased response in the draining lymph nodes that would shift to also include Th17 around the onset of arthritis. Data showed that Th1 and Th17 constitute a minority among the CII-specific population, however, indicating that additional subpopulations of antigen-specific T cells regulate the development of CIA. Conclusions: The established system enables the detection and detailed phenotyping of T cells specific for the galactosylated CII peptide and constitutes a powerful tool for analysis of the importance of these cells and their effector functions throughout the different phases of arthritis.
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| 19. |
- Premanandh, Jagadeesan, et al.
(författare)
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Molecular characterization of marine cyanobacteria from the Indian subcontinent deduced from sequence analysis of the phycocyanin operon (cpcB-IGS-cpcA) and 16S-23S ITS region
- 2006
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Ingår i: Journal of Microbiology. - 1225-8873. ; 44:6, s. 607-616
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Tidskriftsartikel (refereegranskat)abstract
- Molecular characterization of ten marine cyanobacterial isolates belonging to the order Oscillatoriales was carried out using the phycocyanin locus (cpcBA-IGS) and the 16S-23S internally transcribed spacer region. DNA sequences from the phycocyanin operon discriminated ten genotypes, which corresponded to seven morphotypes identified by traditional microscopic analysis. The cpcB coding region revealed 17% nucleotide variation, while cpcA exhibited 29% variation across the studied species. Phylogenetic analyses support the conclusion that the Phormidium and Leptolyngbya genera are not monophyletic. The nucleotide variations were heterogeneously distributed with no or minimal informative nucleotides. Our results suggest that the discriminatory power of the phycocyanin region varies across the cyanobacterial species and strains. The DNA sequence analysis of the 16S-23S internally transcribed spacer region also supports the polyphyletic nature of the studied oscillatorian cyanobacteria. This study demonstrated that morphologically very similar strains might differ genotypically. Thus, molecular approaches comprising different gene regions in combination with morphological criteria may provide better taxonomical resolution of the order Oscillatoriales.
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| 20. |
- Teneva, I, et al.
(författare)
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Cytotoxicity and apoptotic effects of microcystin-LR and anatoxin-a in mouse lymphocytes
- 2005
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Ingår i: Folia Biologica. - 0015-5500. ; 51:3, s. 62-67
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Tidskriftsartikel (refereegranskat)abstract
- There is an increasing amount of knowledge on the cytotoxic properties of cyanotoxins, but relatively little is known regarding their fine specificity and mechanisms of action. In this study, we investigated the influence of microcystin-LR and AnTx-a on mouse B- and T-lymphocyte subpopulations in vitro. Cyanotoxins significantly decreased the cell viability after 4 and 24 h, compared to the untreated control. After 24 h exposure to microcystin-LR and anatoxin-a, the viability of splenocytes dropped to 23% and 57%, respectively. Our data demonstrate that microcystin-LR induced apoptosis specifically in mouse B cells, probably via the B-cell antigen receptor and mitochondrial pathway, while the T cells were not affected. AnTx-a showed cytotoxic effects on both lymphocyte subpopulations, but the effects were driven by mechanisms different from apoptosis. These findings demonstrate that the cyanotoxins could cause cytotoxic alterations in a variety of cell types different from the major targets, operating via distinct mechanisms.
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| 21. |
- Teneva, Ivanka, et al.
(författare)
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Molecular and phylogenetic characterization of Phormidium species (Cyanoprokaryota) using the cpcB-IGS-cpcA locus
- 2005
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Ingår i: Journal of Phycology. - : Wiley. - 0022-3646 .- 1529-8817. ; 41:1, s. 188-194
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Tidskriftsartikel (refereegranskat)abstract
- The accurate determination of species of Cyanoprokaryota/Cyanophyceae has many important applications. These include the assessment of risk with regard to blooms in water reservoirs as well as the identification of species capable of producing valuable bioactive compounds. Commonly, Cyanoprokaryota are classified based on their morphology. However, morphological criteria are not always reliable because they may change, for example, due to environmental factors. Thus, genetic and molecular analyses are a promising additional approach, but their application has so far been limited to relatively few genera. In light of this, we present here the first characterization of species and strains of the genus Phormidium Kutz. based on the cpcB-IGS-cpcA locus of the phycocyanin operon. In phylogenetic analyses using deduced amino acid sequences of the cpcB-cpcA regions, Phormidium was found to be polyphyletic. This analysis appeared to be dominated by the cpcB region, which is characterized by a relatively high percentage of informative substitutions. The percentage of variable positions within the cpcB-IGS-cpcA locus overall was 16.5%, thereby indicating a level of divergence remarkably higher than that reported for Nodularia and Arthrospira in previous studies relying on cpcB-IGS-cpcA. Further, alignment of informative nucleotide substitutions in the cpcB-IGS-cpcA sequences revealed a mosaic distribution, which may be indicative of genetic recombination events. Finally, the length and sequences of the IGS region alone proved useful as markers to differentiate the cyanobacterial genus Phormidium. However, whether the IGS region per se is sufficiently discriminatory to differentiate between Phormidium species or even strains requires further investigation using newly identified Phormidium sequence data.
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| 22. |
- Teneva, I, et al.
(författare)
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The freshwater cyanobacterium Lyngbya aerugineo-coerulea produces compounds toxic to mice and to mammalian and fish cells
- 2003
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Ingår i: Environmental Toxicology. - : Wiley. - 1520-4081 .- 1522-7278. ; 18:1, s. 9-20
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Tidskriftsartikel (refereegranskat)abstract
- Despite a growing awareness of the presence of cyanobacterial toxins, knowledge about the ability of specific species to produce toxic compounds is still rather limited. It was the overall goal of the current work to investigate if probes derived from the freshwater species Lyngbya aerugineo-coerulea (Kutz.) Gomont, a cyanobacterium frequently found in southern Europe and not previously investigated for the presence of bioactive compounds, were capable of eliciting in vivo and in vitro toxicity. The cyanobacterial extract revealed signs of neuro- as well as hepatotoxicity in mice, although these signs could not be explained by the well-known respective cyanobacterial neuro- and hepatotoxins saxitoxin and microcystin. Cytotoxicity was elicited by the cyanobacterial extract in all mammalian cell lines tested. As well, the rainbow trout liver cell line, RTL-W1, was found to be susceptible to the cytotoxic effects of the extract, although the cytotoxicity was dependent on temperature. In contrast, the cyanobacterial growth medium elicited cytotoxicity independent of temperature, leading to morphological changes indicative of alterations to the cytoskeleton. Overall, the results suggest that Lyngbya aerugineo-coerulea is an important cyanobacterium to be considered for its potential to cause health risks on environmental exposure of it to mammals and fish. Applying a combination of mammalian and piscine cell line bioassays is a unique approach that, combined with chemical analysis, could be used in the future to identify the structure and cellular mechanisms of the as-yet-unknown toxic Lyngbya aerugineo-coerulea metabolites in particular and to screen cyanobacterial extracts for their toxicity in general. (C) 2003 Wiley Periodicals, Inc.
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| 23. |
- Teneva, I, et al.
(författare)
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Toxic potential of five freshwater Phormidium species (Cyanoprokaryota)
- 2005
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Ingår i: Toxicon. - : Elsevier BV. - 0041-0101. ; 45:6, s. 711-725
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Tidskriftsartikel (refereegranskat)abstract
- Among the Cyanoprokaryota (blue-green algae), the genus Phormidium has thus far rarely been studied with respect to toxin production and potentially resulting human and environmental health effects. We here show that five previously unexplored freshwater species of this genus (Ph. bijugatum, Ph. molle, Ph. papyraceum, Ph. uncinatum, Ph. autumnale) are indeed capable of producing bioactive compounds. Phormidium extracts caused weight loss as well as neuro/hepatotoxic symptoms in mice, and in the case of Ph. bijugatum even death. Very low levels of saxitoxins and microcystins, as confirmed by ELISA, were insufficient to explain this toxicity and the differing toxic potencies of the Phormidium species. Qualitative HPLC analyses confirmed different substance patterns and in the future could aid in the separation of fractions for more detailed substance characterisation. The results in vivo were confirmed in vitro using cells of human, mouse and fish. The fish cells responded least sensitive but proved useful in studying the temperature dependence of the toxicity by the Phormidium samples. Further, the human cells were more sensitive than the mouse cells thus suggesting that the former may be a more appropriate choice for studying the impact of Phormidium to man. Among the human cells, two cancer cell lines were more responsive to one of the samples than a normal cell line, thereby indicating a potential anti-tumour activity. Thus, the five freshwater Phormidium species should be considered in environmental risk assessment but as well, as a source of therapeutic agents.
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| 24. |
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| 25. |
- Zidarova, Ralitsa, et al.
(författare)
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Karyological and endosymbiotic notes on two Choricystis species (Trebouxiophyceae, Chlorophyta)
- 2009
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Ingår i: Biologia. - : Springer Science and Business Media LLC. - 0006-3088 .- 1336-9563. ; 64:1, s. 43-47
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Tidskriftsartikel (refereegranskat)abstract
- Two species of the genus Choricystis (Choricystis minor and Choricystis chodatii) have been chromosomally surveyed. In addition, their ability to form symbiotic associations with the ciliate Paramecium bursaria was also investigated. Choricystis minor (clone #8931/1 from strain #8931) was isolated from a moss sample collected on Livingston Island, Maritime Antarctica. Choricystis chodatii (clone #3090/1) was derived from strain #3090 Chodat-type culture (loc. Switzerland, lake Geneva). The karyotypes of both species showed a haploid number of five chromosomes and shared some similarity in the chromosome lengths. The absolute chromosome lengths ranged from 1.25 A mu m to 2.95 A mu m. Studied species possess equal abilities for endosymbiotic associations with Paramecium bursaria. Descriptions of the species and a short discussion on their taxonomical status are given.
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