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  • 1
    Electronic Resource
    Electronic Resource
    Evidence for a functional membrane barrier in the transition zone between the flagellum and cell body of Chlamydomonas eugametos gametes (1986)
    Springer
    Planta 167 (1986), S. 544-553 
    Details
    ISSN: 1432-2048
    Keywords: Chlamydomonas (agglutination) ; Flagellum ; Glycoprotein ; Membrane barrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Evidence is presented which supports the concept of a functional membrane barrier in the transition zone at the base of each flagellum of Chlamydomonas eugametos gametes. This makes it unlikely that agglutination factors present on the surface of the cell body can diffuse or be transported to the flagellar membrane. The evidence is as follows: 1) The glycoprotein composition of the flagellar membrane is very different to that of the cell-body plasma membrane. 2) The flagella of gametes treated with cycloheximide, tunicamycin or α, α′-dipyridyl become non-agglutinable but the source of agglutination factors on the cell body is not affected. 3) Even under natural conditions when the flagella are non-agglutinable, for example in vis-à-vis pairs or in appropriate cell strains that are non-agglutinable in the dark, the cell bodies maintain the normal complement of active agglutinins. 4) When flagella of living cells are labeled with antibodies bound to fluorescein, the label does not diffuse onto the cell-body surface. 5) When gametes fuse to form vis-à-vis pairs, the original mating-type-specific antigenicity of each cell body is slowly lost (probably due to the antigens diffusing over both cell bodies), while the specific antigenicity of the flagellar surface is maintained. Even when the flagella of vis-à-vis pairs are regenerated from cell bodies with mixed antigenicity, the antigenicity of the flagella remains matingtype-specific. 6) Evidence is presented for the existence of a pool of agglutination factors within the cell bodies but not on the outer surface of the cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391231
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  • 2
    Electronic Resource
    Electronic Resource
    Sexual agglutination in Chlamydomonas eugametos before and after cell fusion (1985)
    Springer
    Planta 166 (1985), S. 234-243 
    Details
    ISSN: 1432-2048
    Keywords: Cell fusion (Chlamydomonas gametes) ; Chlamydomonas (agglutination) ; Flagellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new study of sexual agglutination between Chlamydomonas eugametos gametes and between vis-à-vis pairs has been made using techniques that allow one to distinguish between the flagella or cell bodies of individual mating types (mt+ or mt-). It is shown that before mt+ and mt- gametes fuse in pairs, their flagella, which adhere over their whole length, are maintained in a particular conformation around the mt- cell body. In clumps of agglutinating gametes the cells are asymmetrically distributed with the mt+ gametes constituting the outer surface of the clumps with the mt- gametes on the inside. The flagella are then all directed towards the middle of the clump. This orientation of the flagella is maintained for approx. 8 min after cell fusion before the vis-à-vis pair becomes motile. At this stage, all the flagellar tips are activated. The original mt+ flagellar tips then deactivate and swimming is resumed. The original mt- flagella remain immotile and activated after cell fusion and eventually shorten by a third, but only 30 min or more after fusion. Motile vis-à-vis pairs eventually settle to the substrate when the gamete bodies fuse completely to form a zygote. Settling vis-à-vis pairs are attracted to those that have already settled, to glutaraldehyde-fixed pairs and to flagella isolated from mt- gametes. They are not chemotactically attracted, rather they are weakly agglutinated. Living vis-à-vis pairs can be shown to aggregate in rows with the cell bodies lying side by side. It is argued that the flagellar agglutination sites involved in gamete recognition are also involved in vis-à-vis pair aggregation
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397354
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  • 3
    Electronic Resource
    Electronic Resource
    Light dependence of sexual agglutinability in Chlamydomonas eugametos (1986)
    Springer
    Planta 169 (1986), S. 370-378 
    Details
    ISSN: 1432-2048
    Keywords: Agglutination (flagellum) ; Chlamydomonas ; Flagellum ; Light (flagellar agglutination) ; Sexuality (algal)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mating activity of mating-type plus gametes of Chlamydomonas eugametos depends on light. Cells lost their ability to agglutinate with mating-type minus gametes after a dark period of 30 min. They regained their agglutinability after 10 min exposure to light. Other mating reactions, such as tipping and flagellar tip activation, were not dependent upon light. Since cycloheximide and tunicamycin did not affect the light-induced activation of flagellar agglutinability, no protein synthesis or glycosylation is involved in this process. Equal amounts of biologically active agglutination factor could be extracted from cells placed either in light or in darkness. A minor portion of the active material was found to be located on the flagellar surface of illuminated cells. No active material was found on the flagellar surface of dark-exposed cells, whereas their cell bodies contained the same amount of active material as the cell bodies of illuminated cells. Since a light-induced flow of agglutination factors from the cell body to the flagella could not be detected and dark-exposed cells could be slightly activated by amputation or fixation by glutaraldehyde, we propose that light affects flagellar agglutinability by an in-situ modification of the agglutination factor on the flagella. When mt + and mt - strains were crossed and the progeny examined for light-sensitivity, it was apparent that this phenomenon is not mating type-linked.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392133
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  • 4
    Electronic Resource
    Electronic Resource
    Cell-cell coordination in conjugatingChlamydomonas gametes (1990)
    Springer
    Protoplasma 155 (1990), S. 188-199 
    Details
    ISSN: 1615-6102
    Keywords: Adhesion ; Agglutinin ; Chlamydomonas ; Conjugation ; Flagellum ; Gamete ; Signalling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary During conjugation, complementaryChlamydomonas gametes [mating type plus (mt+) and mating type minus (mt−)] are mutually attached via specific adhesion molecules, called agglutinins, which are located at the surface of the flagella. By these contacts the gametes are stimulated to fuse. It is demonstrated that fusion is preceded by a compulsary sequence of events: first, the flagellar swimming beat is arrested, next the flagellar contact is reinforced and finally, the position of the cell bodies is adjusted to permit fusion. Evidence is presented that each consecutive step of the mating process requires a higher level in cell-cell signalling, which is obtained by the formation of additional agglutinin contacts. It is shown that the mt+ and mt− traverse their conjugation process in synchrony, probably because the two sexes acquire new agglutinin contacts at equal rates. It is proposed that this symmetrical behavior is due to the complementarity of the mt+ and mt− agglutinin molecules. A scenario of the conjugation process inC. eugametos, incorporating the recent findings, is provided.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01322628
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  • 5
    Electronic Resource
    Electronic Resource
    Turnover and transport of agglutinins in conjugatingChlamydomonas gametes (1990)
    Springer
    Protoplasma 155 (1990), S. 200-209 
    Details
    ISSN: 1615-6102
    Keywords: Cell adhesion,Chlamydomonas ; Flagellum ; Gamete activation ; Receptor turnover ; Sexual agglutinins ; Signalling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary During gamete-gamete adhesion in the unicellular green algaChlamydomonas eugametos, the sexual adhesion molecules or agglutinins that are located on the flagella are subject to tip-oriented migration and rapid inactivation. It is demonstrated that sexual adhesiveness is maintained by incorporation of additional agglutinins, recruited from a cellular pool. The location of this reservoir is unknown but, as indicated by its insensitivity to the chaotropic agent guanidine thiocyanate, it appears to be distinct from the large amount of agglutinins on the plasma membrane of the cell body. By viewing flagella of conjugating gametes in a confocal scanning laser microscope after immuno-labelling of the agglutinins, evidence was obtained for a linear arrangement of the agglutinins in two rows on the flagellar surface. This suggests that after insertion at the base of the flagellum, the agglutinins follow linear tracks to the tip and that the transport system is confined to two longitudinal domains. It is estimated that the half-life of flagellar agglutinins drops from 1–2 h in nonconjugating gametes to 1 min during conjugation, which suggests that after incorporation at the flagellar base, the agglutinins migrate to the tip with a velocity of 100 nm/s. Presumably after arrival at the tip, the molecules are inactivated. It is postulated that rapid turnover and transport of agglutinins are required for optimal signalling between partner gametes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01322629
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  • 6
    Electronic Resource
    Electronic Resource
    Cell-cell adhesion in conjugatingChlamydomonas gametes: a self-enhancing process (1988)
    Springer
    Protoplasma 145 (1988), S. 27-36 
    Details
    ISSN: 1615-6102
    Keywords: Adhesion ; Agglutinin ; Chlamydomonas ; Flagellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The flagellar adhesiveness of gametes ofChlamydomonas eugametos increases during conjugation such that the cell-cell contacts are intensified. The rise in adhesiveness is due to an increase in agglutinin exposure which can be visualized by immunolabeling. The adhesiveness in the one cell is stimulated by the agglutinins of the adherent partner cell, and vice versa. Thus, sexual cell-cell adhesion is a self-enhancing process. In addition, it is shown that the gametes are able to activate potential partners at distance via agglutinin-rich vesicles which they shed into their environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01323253
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  • 7
    Electronic Resource
    Electronic Resource
    Kurzzeituntersuchungen an Lichtquellen für die Spektralanalyse (1962)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 74 (1962), S. 157-157 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19620740417
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrazentrifugenuntersuchungen im Dichtegradienten (1964)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 76 (1964), S. 351-351 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19640760833
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  • 9
    Electronic Resource
    Electronic Resource
    The coil dimensions of hexene-1 polysulfone in θ-solvents (1961)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 54 (1961), S. S17 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1961.1205415927
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  • 10
    Electronic Resource
    Electronic Resource
    New cell designs for density gradient centrifugation (1964)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 78 (1964), S. 140-145 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Drei Entwürfe für Doppelsektor-Zellen werden vorgeschlagen. Die Entwürfe machen es möglich, Dichtegradienten-Versuche mit in beiden Sektoren gleichen Säulenhöhen auszuführen. Sie garantieren auch, daß die Säulenhöhen von Versuch zu Versuch identisch sind.
    Notes: Three different designs for double sector cells are presented. The designs allow density gradient experiments to be carried out with equal column lengths in each sector. Also they assure equal heights of the columns from experiment to experiment.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1964.020780111
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