| 1. |
- Rosén, Stefan, et al.
(författare)
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A multispecific saline-soluble lectin from the parasitic fungus Arthrobotrys oligospora. Similarities in the binding specificities compared with a lectin from the mushroom agaricus bisporus.
- 1996
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Ingår i: European journal of biochemistry / FEBS. - : Wiley. - 0014-2956 .- 1432-1033. ; 238:3, s. 830-7
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Tidskriftsartikel (refereegranskat)abstract
- Several fungi can express high levels of saline-soluble and low-molecular-mass lectins that bind to glycoproteins such as fetuin and different mucins but not bind to any monosaccharides. In this paper, we report the binding specificities of such a lectin (designated AOL) isolated from the nematophagous fungus Arthrobotrys oligospora. The results show that AOL is a multispecific lectin that interacts with the following ligands: (a) Several sulfated glycoconjugates including sulfatide, dextran sulfate, and fucoidan. The specificity of this binding was indicated by experiments showing that none of the tested neutral- and sialic-acid-containing glycolipids, chondroitin sulfates B and C, heparin, and polyvinyl sulfate bound to AOL; (b) Phosphatidic acid and phospatidylglycerol, two out of several tested phospholipids. (c) N-linked and O-linked sugar chains bound to intact fetuin. The involvement of such sugar structures was demonstrated by analyzing the binding of AOL to chemically deglycosylated (trifluoromethanesulfonic acid) fetuin. Treating fetuin with O-glycosidase and N-glycosidase indicated that AOL bound to Gal beta GaLNAc alpha-Ser/Thr and to some N-linked complex sugars, respectively. Further assays demonstrated that AOL could interact with several other glycoproteins containing O-linked and/or N-linked sugar chains. The observations that AOL did not bind to free N-linked sugars isolated from fetuin, or to fetuin treated with trypsin or pronase, or to any of the tested neoglycoproteins and glycolipids with neutral- or sialic acid-containing sugars, indicated that the sugar chains need to be bound to an intact peptide backbone to interact with AOL. We have recently shown that the deduced primary structure of AOL has a high similarity to the sequence of a saline-soluble lectin isolated from the mushroom Agaricus bisporus (ABL) (Rosén, S., Kata, M., Persson, Y., Lipniunas, P. H., Wikström, M., van den Hondel, C. A. M. J. J., van den Brink, J. M., Rask, L., Hedén L.-O. and Tunlid, A., see companion paper). It is well known that ABL binds to Gal beta 3GaLNAc alpha-Ser/Thr, and in this paper we demonstrate that ABL binds to sulfatide, phosphatidic acid, phospatidylglycerol, and possibly also to the same N-linked complex sugars as AOL. The above data indicate that AOL and ABL are members of a novel family of fungal lectins sharing similar primary structure and binding properties.
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| 4. |
- Hedenström, Anders, et al.
(författare)
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Flight performance during hunting excursions in Eleonora's falcon Falco eleonorae
- 1999
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 202:15, s. 2029-2039
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Tidskriftsartikel (refereegranskat)abstract
- Among birds, falcons are high-performance flyers, in many cases adapted for aerial hunting and hence suitable targets for investigating limits to flight performance. Using an optical range finder, we measured flight tracks of Eleonoras falcon (Falco eleonorae), a species breeding in the Mediterranean region and specialised for hunting autumn passage bird migrants, when commuting between their nesting colony and offshore hunting areas (straight transportation flight) and when searching for prey (transecting and searching flight). Airspeed during searching flight was significantly slower than during straight transportation and transecting flight, but there was no significant difference in airspeed between the latter two flight modes. Straight transportation flight was significantly faster than predicted minimum power speed. Also, during straight transportation flight, the falcons responded to head- and tailwinds by increasing their airspeed when flying into the wind. However, they did not show any significant airspeed adjustments with respect to the angle between the track and the heading, as would be expected in birds trying to maintain a constant track direction. Mean sustainable climb rate (during (greater than or equal to) 240 s) was 1.4+/-0.31 m s-1 (mean +/- s.d., N=13), which is rather a high rate for a bird the size of an Eleonoras falcon. The climb rate was used to calculate maximum load-carrying capacity and maximum sustained horizontal flapping flight speed. The mean wingbeat frequency during powered climbing flight was 4.68 Hz, which was used to estimate the mass-specific muscle work. When falcons were leaving the colony for offshore hunting, they gained altitude by slope-soaring when there was an onshore wind. We formulated a simple criterion for the required gliding-flight rate of climb during an initial slope-soaring episode when minimizing the energy cost of reaching a certain altitude far out over the sea (which is where the prey is to be found). This climb rate was 0.36 m s-1, and our observations indicated that the falcons experienced climb rates above this value when soaring in slope-lift.
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| 5. |
- Rosén, Stefan, et al.
(författare)
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A cytoplasmic lectin produced by the fungus Arthrobotrys oligospora functions as a storage protein during saprophytic and parasitic growth
- 1997
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Ingår i: Microbiology. - : Microbiology Society. - 1350-0872 .- 1465-2080. ; 143:8, s. 2593-2604
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Tidskriftsartikel (refereegranskat)abstract
- It was recently shown that the nematode-infecting fungus Arthrobotrys oligospora contains a saline-soluble lectin (designated AOL) that is a member of a novel family of fungal lectins sharing similar primary sequences and binding specificities. During saprophytic growth in liquid cultures, levels of AOL and AOL mRNA were found to vary depending on the growth phase of the mycelium and the carbon/nitrogen (C/N) ratio of the medium. AOL was not detected in young mycelium. In older mycelium (stationary growth phase) grown in media with low UN ratios (1 or 6), AOL comprised 5-20% of the total amount of saline-soluble proteins present in the mycelium. Neither the lectin nor its transcript was detected in mycelia grown in medium with higher C/N ratios (≤ 150). Under conditions of nitrogen starvation, AOL was preferentially degraded in relation to the total amount of saline-soluble proteins present in the mycelium. During the infection of nematodes, the level of AOL protein and AOL mRNA increased significantly once the nematodes had been penetrated and digested. Large amounts of AOL accumulated in the trophic hyphae growing inside the nematode as visualized by immunofluorescence microscopy. Later, AOL labelling was detected outside the digested nematodes, preferentially in strands of aggregated hyphae and in newly developed trap cells. Electron microscopy showed that AOL was localized to the cytoplasm and the nucleus-of both vegetative mycelium and trap cells, and in the trophic hyphae growing inside the infected nematodes. These results indicate that AOL functions as a storage protein during both saprophytic and parasitic growth.
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| 6. |
- Rosén, Stefan, et al.
(författare)
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Molecular characterization of a saline-soluble lectin from a parasitic fungus : Extensive sequence similarities between fungal lectins
- 1996
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Ingår i: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 238:3, s. 822-829
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Tidskriftsartikel (refereegranskat)abstract
- It has been proposed that the interactions between several parasite and pathogenic fungi and their hosts are mediated by soluble lectins present in the fungus. We have cloned and analyzed a gene encoding such a lectin (AOL) from the nematophagous fungus Arthrobotrys oligospora (deuteromycete). The deduced primary structure of the AOL gene displayed an extensive similarity (identity 46.3%) to that of a gene encoding a lectin (ABL) recently isolated from the mushroom Agaricus bisporus (basidiomycete), but not to any other fungal, microbial, plant, or animal lectins. The similarities between AOL and ABL were further demonstrated by the observation that an antibody specific for AOL cross-reacted with ABL. Together with data showing that AOL has a binding specificity that is similar to that of ABL [Rosen, S., Bergstrom, J., Karlsson, K.-A., and Tunlid, A. (1996) Eur. J. Biochem. 238, 830-837], these results indicate that AOL and ABL are members of a novel family of saline- soluble lectins present in fungi. Southern blots indicated that there is only one AOL gene in the genome encoding a subunit (monomer) of the lectin. The primary structure of AOL did not show the presence of a typical N-terminal signal sequence. Comparison of the deduced primary structure with the molecular mass of AOL as determined by electrospray mass spectrometry (16153 Da), indicated that AOL has an acetylated N-terminal but no other post- translational modifications, and that a minor isoform is formed by deamidation. Circular dichroism (CD) spectroscopy suggested that the secondary structure of AOl contains 34% β-sheets, 21% α-helix, and 45% turns and coils.
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| 7. |
- Sahaf, Bita, et al.
(författare)
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Thioredoxin Expression and Localization in Human Cell Lines : Detection of Full-Length and Truncated Species
- 1997
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Ingår i: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 236:1, s. 181-192
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Tidskriftsartikel (refereegranskat)abstract
- Thioredoxin (Trx) is an intracellular multifunctional 12-kDa protein with a reduction/oxidation (redox) active disulfide constitutively expressed by most cells of the human body. Trx can also be released by cells such as lymphocytes upon activation or oxidative stress exposure and exert a cocytokine and cytoprotective activity. In addition, a truncated 10-kDa form of Trx has been reported. In order to better understand the function of full-length and truncated Trx, we have produced, for the first time, specific monoclonal antibodies, which can discriminate between the two forms. Using these novel antibodies, designated αTrx1 to αTrx4, a panel of cell lines derived from human B and T lymphocytes, monocytes, granulocytes, and melanomas was analyzed by immunochemical techniques. The cellular distribution differed between the two forms. All lines contained full-length Trx, also located to a minor extent on the cell surface. One exception was the melanoma cell line FM28.4, which did not show any Trx expression. Truncated Trx was present in most cells in minimal amounts only, whereas the monocytic cell lines THP-1 and U-937 expressed high amounts on the cell surface, as shown by flow cytometric analysis of living cells and confocal laser-scanning microscopy. The biological importance and function of the short versus long forms of Trx as detected by the antibodies are discussed.
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| 8. |
- Savolainen, Peter, et al.
(författare)
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Sequence analysis of domestic dog mitochondrial DNA for forensic use
- 1997
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Ingår i: Journal of Forensic Sciences. - : ASTM International. - 0022-1198 .- 1556-4029. ; 42:4, s. 593-600
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Tidskriftsartikel (refereegranskat)abstract
- A method has been developed for the direct sequencing of hypervariable region 1 (HV1) of domestic dog (Canis familiaris) and wolf (Canis lupus) mitochondrial DNA (mtDNA) using single hairs as template. The method uses a robotic work-station and an automated sequencer to allow for robust routine analysis. A population data base was created in order to investigate the forensic and population-genetic informativeness of domestic dog HV1. Sequence variation, partitioning of dog breeds among sequence variants and phylogenetic relations between the variants were determined. Samples from 102 domestic dogs of 52 different breeds and two captive wolves were analyzed. Nineteen dog sequence variants were found and the frequencies of the variants ranged from 1 to 21%. The calculated discrimination power of the region, i.e., the exclusion capacity, implied that nine out of ten disputed individuals can be excluded by this analysis. The sequence variants were found to cluster into four phylogenetic groups.
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| 9. |
- Söderberg, Anita, et al.
(författare)
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Monoclonal Antibodies to Human Thioredoxin Reductase
- 1998
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 249:1, s. 86-89
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Tidskriftsartikel (refereegranskat)abstract
- The thioredoxin system consisting of thioredoxin (Trx), thioredoxin reductase (TrxR), and NADPH is an electron donor for ribonucleotide reductase but has also been implicated in other cellular events, including secretion, growth promotion, regulation of transcription factors, protection against oxidative stress, and apoptosis. Mammalian TrxR is a dimeric flavoprotein with 58 kDa subunits each with a catalytically active selenocysteine residue. To study the function and expression of TrxR, we have produced and characterized, for the first time, monoclonal antibodies against human TrxR. Native placenta TrxR was used for immunization of BALB/c mice, followed by hybridization, cloning, and establishment of hybridomas producing specific antibodies against human TrxR. Three clones of IgG1,κ subclass, termed anti-TrxR1, anti-TrxR2, and anti-TrxR3, were studied in detail. The isoelectric points (pIs) of the mAbs were 6.5, 6.0, and 6.5, respectively. The affinities (Ka) of the mAbs were 2 × 108M−1.Inhibition ELISA using biotin-labeled versus nonconjugated mAb IgG revealed that all three mAbs recognized one immunodominant epitope. Western blot analysis showed that the antibodies specifically bound to a 58 kDa protein, representing the subunit of TrxR. A Trx-dependent insulin reduction assay was used for analysis of enzymatic activity and the antibodies neutralized the reductase activity.
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