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- Kiemel, K., et al.
(författare)
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Variation in heat shock protein 40 kDa relates to divergence in thermotolerance among cryptic rotifer species
- 2022
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Genetic divergence and the frequency of hybridization are central for defining species delimitations, especially among cryptic species where morphological differences are merely absent. Rotifers are known for their high cryptic diversity and therefore are ideal model organisms to investigate such patterns. Here, we used the recently resolved Brachionus calyciflorus species complex to investigate whether previously observed between species differences in thermotolerance and gene expression are also reflected in their genomic footprint. We identified a Heat Shock Protein gene (HSP 40 kDa) which exhibits cross species pronounced sequence variation. This gene exhibits species-specific fixed sites, alleles, and sites putatively under positive selection. These sites are located in protein binding regions involved in chaperoning and may therefore reflect adaptive diversification. By comparing three genetic markers (ITS, COI, HSP 40 kDa), we revealed hybridization events between the cryptic species. The low frequency of introgressive haplotypes/alleles suggest a tight, but not fully impermeable boundary between the cryptic species.
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| 4. |
- Kassner, A, et al.
(författare)
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Molecular structure and interaction of recombinant human type XVI collagen
- 2004
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 1089-8638 .- 0022-2836. ; 339:4, s. 835-853
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Tidskriftsartikel (refereegranskat)abstract
- Collagen XVI is a minor component of at least two different extracellular fibrillar networks of specialized regions of skin and cartilage. In skin, collagen XVI is integrated into particular fibrillin-rich microfibrils lacking an amorphous elastin core. In cartilage, collagen XVI is a component of small heterotypic D-banded fibrils, mainly occurring in the territorial matrix of chondrocytes. Here, we present the first direct evidence for the molecular structure and functional properties of these fibril-associated collagens with interrupted triple helices (FACIT). We have expressed recombinantly the full-length alpha1 chain of human collagen XVI in HEK 293 EBNA cells in large quantities using an episomal expression system. Secreted full-length recombinant collagen XVI forms stable disulfide-bonded homotrimers and is rapidly proteolytically processed to distinct fragments at specific protease sequence motifs, one resembling an aggrecanase recognition site. Limited trypsin digestion assays and thermal transition curves imply sequential thermal denaturation of individual triple helical domains of this recombinant collagen, similar to authentic collagen XVI. Molecular images of collagen XVI reveal rod-like molecules which harbor multiple sharp kinks attributing a highly flexible structure presumably introduced by non-collagenous (NC) regions. Terminally located cloverleaf-shaped nodules correspond to the large NC NC11 domain of trimeric collagen XVI. The total length of individual trimeric recombinant collagen XVI molecules constitutes about 240 nm as calculated by atomic force and negative staining electron microscopy. Recombinant collagen XVI interacts with fibrillin-1 and with fibronectin indicating multiple molecular interactions in which this ubiquitously expressed and versatile FACIT-collagen can participate. In vitro generated collagen XVI provides an indispensable tool for future determination of its function during supramolecular assembly of matrix aggregates and its role in maintenance, organization and interaction of fibrillar structures. (C) 2004 Elsevier Ltd. All rights reserved.
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| 6. |
- Tiedemann, K, et al.
(författare)
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Cytokine regulation of proteoglycan production in fibroblasts : separate and synergistic effects
- 1997
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Ingår i: Matrix (Stuttgart, Germany). - 0945-053X. ; 15:7, s. 78-469
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the effects of cytokines, separately or in combination, on the production of proteoglycans in confluent cultures of fibroblasts. The cytokines used were the transforming growth factor-beta (TGF-beta), the platelet derived growth factor-AA (PDGF-AA), the platelet derived growth factor-BB (PDGF-BB) and the epidermal growth factor (EGF). Hyaluronan production increased in cells treated with TGF-beta, PDGF-AA and PDGF-BB. Combining pairs of factors did not contribute further to hyaluronan production, whereas the triple combination of EGF, TGF-beta and PDGF-BB induced an additional 1.9-fold increase. Proteoglycan production was only increased by TGF-beta alone. As for hyaluronan, combining pairs of the cytokines had no further effect on metabolism, whereas the combination of EGF, TGF-beta and PDGF-BB induced a further 1.6-fold increase in production and secretion. Compared with the control, an extensive increase in proteoglycan production was generated by the combination of EGF, TGF-beta and PDGF-BB, 7-fold for biglycan, approximately 5-fold for versican and hyaluronan and 2.4-4-fold for heparan sulfate proteoglycan and decorin. Compared with TGF-beta alone, this combination increased, in falling order, the production of heparan sulfate proteoglycan, hyaluronan, biglycan, decorin and versican. The mRNA levels for the various proteoglycans did not completely agree with the changes in production, suggesting that changes not only in synthesis but also in rate of degradation generate these variations. The data indicate that cytokines cooperate to produce a proper and physiological response, one needed by the organism during physiological and pathophysiological remodeling.
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| 7. |
- Tiedemann, K, et al.
(författare)
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Regulation of the chondroitin/dermatan fine structure by transforming growth factor-beta 1 through effects on polymer-modifying enzymes
- 2005
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 1460-2423 .- 0959-6658. ; 15:12, s. 1277-1285
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Tidskriftsartikel (refereegranskat)abstract
- The chondroitin/dermatan sulfate proteoglycans (CS/DSPGs), biglycan, decorin, and versican play several important roles in extracellular matrix influencing matrix organization, cell proliferation, and recruitment. Moreover, they bind and regulate growth factors in the extracellular matrix. We have previously shown that cultured human lung fibroblasts treated with transforming growth factor-beta (TGF-beta) alone or in combination with epidermal growth factor and platelet-derived growth factor, increase the production of these PGs. In this report, we describe that the structure of their galactosaminoglycan side chains is altered, albeit there is no alteration of polysaccharide length. The findings showed that iduronic acid content is reduced by 50% in decorin and biglycan, whereas 4-O-sulfation is increased 2-fold in versican. To unravel the mechanism behind these changes, the activities of chondroitin C-5 epimerase and of O-sulfotransferases in cellular fractions prepared from fibroblasts were quantitated, and transcript levels of the relevant sulfotransferases were measured by real time polymerase chain reaction (RT-PCR). The C-5 epimerase activity was reduced by 25% in TGF-beta 1 treated cells and 50% in fibroblasts treated with the growth factor combination. No change in activity in dermatan 4-O sulfotransferase was observed, and only a minor decrease in dermatan 4-O-sulfotransferase-1 (D4ST-1) mRNA was observed. On the other hand, chondroitin 4-O sulfotransferase activity increased 2-fold upon TGF-beta 1 treatment and 3-fold upon treatment with the growth factor combination. This is in agreement with a 2-fold up-regulation of chondroitin-4-O-sulfotransferase 1 (C4ST-1) mRNA, and no changes in chondroitin-4-O-sulfotransferase 2 (C4ST-2) mRNA. Thus, cellular activity and transcript level correlated well with the changes in the structure of the dermatan/chondroitin sulfate chains.
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