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    Abstract: Dynamic polarisation of tumour cells is essential for metastasis. While the role of polarisation during dedifferentiation and migration is well established, polarisation of metastasising tumour cells during phases of detachment has not been investigated. Here we identify and characterise a type of polarisation maintained by single cells in liquid phase termed single-cell (sc) polarity and investigate its role during metastasis. We demonstrate that sc polarity is an inherent feature of cells from different tumour entities that is observed in circulating tumour cells in patients. Functionally, we propose that the sc pole is directly involved in early attachment, thereby affecting adhesion, transmigration and metastasis. In vivo, the metastatic capacity of cell lines correlates with the extent of sc polarisation. By manipulating sc polarity regulators and by generic depolarisation, we show that sc polarity prior to migration affects transmigration and metastasis in vitro and in vivo.
    Type of Publication: Journal article published
    PubMed ID: 29491397
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  • 3
    ISSN: 0921-8734
    Keywords: Mitochondrial DNA ; Mobile intron delayed amplification ; Podospora anserina
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0983
    Keywords: Saccharomycopsis lipolytica ; mtDNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitochondrial (mt) DNA of the alkane yeast, Saccharomycopsis lipolytica, was isolated. Its buoyant density in CsCl was found to be of 1.687 g/cm3, indicating a GC content of 27.5% and its melting point Tm = 79.5 °C, indicating a GC content of 24.9%. The corresponding values for nuclear (n) DNA, are 1.709 g/cm3 (GC: 49.5%) and Tm = 90.5 (GC: 51.7%) respectively. Electron microscopy revealed that mtDNA has a circular structure with a contour length of about 14.5 µm corresponding to 45.5 kb per molecule. The size estimated from restriction analyses performed with 7 endonucleases was 48.35 kb/molecule. A restriction map was constructed, using the cleavage data of 4 endonucleases.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0983
    Keywords: Podospora anserina ; mt plasmid ; DNA sequence ; Mobile intron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the ascomycete Podospora anserina strain ageing (senescence) is caused by a mitochondrial plasmid. In juvenile mycelia it is an integral part of the mtDNA and becomes liberated during ageing. The nucleotide sequence of this plasmid and of its flanking regions was determined. It consists of 2,539 by and contains an un identified reading frame (URF) originating in the adjacent mtDNA upstream of excision point 1. Within the URF a putative 48 by autonomously replicating sequence (ars) was identified. At both excision sites of the plasmid there are two short nonidentical interrupted palindromes and a few base pairs apart from these palindromes, both upstream and downstream, two short inverted repeats are localised. The experimental data make it evident that the mt plasmid is an intron of the cytochrome c oxidase gene (subunit I) which may be excised at the DNA level and thus become the mobile infective agent causing senescence. The concept of this mobile intron and current hypotheses concerning the relationship between introns and transposons are stressed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 48 (1964), S. 306-318 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Laccase of the wild strain of Podospora anserina was purified by subsequent treatment with protamine sulfate, precipitation with ammonium sulfate and column chromatography on DEAE-Sephadex and hydroxylapatite. The purity was confirmed by sedimentation and electrophoresis (molecular weight about 361 000, isoeletric point at pH 5.1). The blue-coloured pure laccase has its absorption-maxima at 280 and 605 mμ. The substrate specifity of the enzyme corresponds to results which have been earlier obtained with unpurified preparations (Esser 1963 b). Laccase is very temperature sensitive. It loses its activity after both freezing and heat treatment (half-life time at 60°C about 6 min). The Michaelis-constants as determined with Dopa, potassium ferrocyanide and catechol are in the range of 2 to 5·10-3 Mol/l. The appropriate value for ascorbic acid is about 10-2 less. The laccase contains about 12% carbohydrate and about 7,5% nitrogen. According to its copper content of 0.123% the laccase carries seven atoms of copper per molecule.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 65 (1969), S. 146-162 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die Tyrosinase der Mutantezonata (z) vonPodospora anserina wurde untersucht. Die Mutante erzeugt im Vergleich zum Wildstamm große Mengen Tyrosinase.z ist eine morphologische Mutante mit rhythmischen Wuchs. Das Genz liegt auf dem rechten Arm der Koppelungsgruppe II und hat einen Abstand von 46 Kartierungseinheiten vom Centromer. Die Reinigung des Enzyms erfolgte durch Präzipitation mit Protaminsulfat, Ammoniumsulfat und anschließende Säulenchromatographie an DEAE-Sephadex und Hydroxylapatit. Die Einheitlichkeit des gereinigten Enzyms wurde in der Ultrazentrifuge und der Elektrophorese festgestellt. Das gereinigte Enzym ist in verdünnter Lösung instabil. Im Konzentrationsbereich von 2–15 mg/ml hat die Tyrosinase eine Sedimentationskonstante vons 20,w 0 =6,04. Die Molekulargewichtsbestimmung aus Diffusion und Sedimentation und aus dem Sedimentationsgleichgewicht nachYphantis ergab in demselben Konzentrationsbereich ein Molekulargewicht um 100.000. Bei einer Enzymkonzentration von 0,04 mg/ml fanden wir mit der Gelfiltrations-methode nur ein Molekulargewicht von 42.000. Aus diesen Resultaten läßt sich in Übereinstimmung mit den Ergebnissen an anderen Tyrosinasen aus Pilzen eine konzentrationsabhängige Assoziation und Dissoziation des Enzyms folgern. Der Kupfergehalt beträgt 0,214±0,008%. Das gereinigte Enzym hat ein Absorptionsmaximum bei 280 nm und eine Schulter bei 290 nm und von 320 bis 380 nm. Das Verhältnis von Dehydrogenierungen an Brenzcatechin zu Hydroxylierungen an Hydrochinon konnte polarographisch bestimmt werden. Es läuft im Mittel auf zwei Dehydrogenierungen nur eine Hydroxylierung ab. Natriumazid wirkt als reversibler und kompetitiver Inhibitor der Dehydrogenierungsreaktion. Im Rohextrakt liegt das Enzym in einer latenten Form vor. Es sind nur 10–20% der späteren Aktivität nachzuweisen. Das Enzym wird im Verlauf der Reinigungsprozedur oder durch Temperaturbehandlung (10 min bei 60°C) aktiviert. Der Aktivierungsvorgang ist von einer Veränderung der elektrophoretischen Beweglichkeit des Enzyms begleitet. Latentes und aktives Enzym unterscheiden sich nicht in ihrem Sedimentationsverhalten.
    Notes: Summary Tyrosinase of the mutantzonata (z) ofPodospora anserina was investigated. In comparison to the wild strain the mutant (z) produces large quantities of tyrosinase.z is a morphological mutant with rhythmic growth. The genez is localized on the right arm of linkage group II at a distance of 46 map-units from the centromere. The enzyme was purified by precipitation with protamine-sulphate and ammonium sulphate and by subsequent column-chromatography on DEAE-Sephadex and hydroxylapatite. The homogeneity of the purified enzyme was checked by ultracentrifugation and disc-electrophoresis. The purified enzyme is unstable in dilute solution. At a concentration of 2–15 mg/ml the tyrosinase has a sedimentation constant ofs 20,w 0 =6.04. The determination of molecular weight from sedimentation and diffusion constants and from sedimentation-equilibrium according toYphantis showed a molecular weight of approximately 100,000 in the same concentration range. At an enzyme concentration of 0.04 mg/ml we found a molecular weight of only 42,000 using the gel-filtration technique. From these results, in accordance with the results obtained from other tyrosinases in fungi, association and dissociation of the enzyme dependent on concentration may be concluded. The copper content reaches a level of 0.214±0.008%. The purified enzyme has an absorption maximum at 280 nm and a shoulder at 290 nm and from 320 to 380 nm. The quotient of catechol-dehydrogenations to hydroquinone-hydroxylation was determined polarographically. The mean ratio is two dehydrogenations to only one hydroxylation. Sodium azide acts as a reversible and competitive inhibitor of the dehydrogenation-reaction. In the crude extract the enzyme is found in a latent form. Only 10–20% of its later activity can be demonstrated. The enzyme is activated in the course of the purification procedure or by temperature treatment (10 min at 60°C). The activation process is accompanied by a change in the electrophoretic mobility of the enzyme. Latent enzyme and active enzyme do not differ in their sedimentation behaviour.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 77 (1971), S. 140-150 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Mycelial extracts and culture filtrates of two species of Trametes have been assayed for various enzymatic activities. The tests performed after 3 and 10 days of mycelial growth on 3% malt extract have revealed that the spectra of external enzymes secreted by both strains differ markedly from their intracellular equivalents. A great part of the external isozyme bands, shown in disc electrophoresis and isoelectric focusing, have no equivalent acting within the cell. 2. These findings are discussed on the basis of special functional properties which have to be attributed to external enzymes. It is concluded that a great number of them are not simply internal enzymes which happen to be active outside the cell but that they are synthesized or at least modified especially for extracellular action under these special conditions. 3. A comparison between the two species of Trametes has shown that both produce enzymes with identical function. This indicates their strong relationship, though the electrophoretic mobility of most of the enzymes is not comparable. The consequences of these findings for chemical taxonomy are discussed.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-0983
    Keywords: Ascobolus immersus ; Linear plasmids ; Inverted repeats ; Terminal proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In seven out of eleven wild strains of the Ascomycete Ascobolus immersus plasmid DNA was found. There was great variability with respect to size and number of the plasmids in the strains concerned. For a further analysis two plasmids originating from one wild strain were submitted to restriction analysis and electron microscopy. Both turned out to be linear having different molecular weights (pAIl = 7.9 kb, pAI2 = 5.6 kb). Denaturation of pAI2 and subsequent renaturation revealed the presence of inverted repeats (0.7 kb) at both ends. After treatment with proteinase K and 5′ and 3′ specific exonucleases it became evident that the 5′ ends of pAI2 are linked with proteins. In this respect it is similar in structure to other linear genetic elements such as the linear plasmids found in Zea mays and the genomes of adenoviruses.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0983
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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