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  • 1
    Electronic Resource
    Electronic Resource
    Preprophasic microtubule systems and development of the mitotic spindle in hornworts (Bryophyta) (1988)
    Springer
    Protoplasma 143 (1988), S. 11-21 
    Details
    ISSN: 1615-6102
    Keywords: Bryophytes ; Immunofluorescence ; Microtubules ; Mitotic apparatus ; Monoplastidy ; Preprophase band
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Studies of monoplastidic mitosis in hornworts (Bryophyta) using transmission electron microscopy and indirect immunofluorescence staining of microtubules have revealed that two mutually perpendicular microtubule systems predict division polarity in preprophase. Events of cytoplasmic reorganization in preparation for division occur in the following order: migration of the single plastid to a position perpendicular to the division site, constriction of the plastid where its midpoint intersects the division site, development of an axial system of microtubules parallel to the elongating plastid isthmus, and appearance of an atypical preprophase band of microtubules (PPB). The PPB is asymmetrical with a tight band of microtubules on the side over the plastid isthmus and a broad band of widely spaced microtubules over the nucleus. The axial system contributes directly to development of the spindle. In prometaphase, the axial system separates at the equator and additional microtubule bundles project from polar regions, creating two opposing halfspindles. The PPB is still present during asymmetrical organization of the spindle and microtubules extending from the broad portion of the PPB to poles appear to be incorporated into the developing spindle. Dynamic changes in the microtubular cytoskeleton demonstrate (1) intimate relationship of plastid and nuclear division, (2) contribution of preprophase/prophase microtubule systems to spindle development in monoplastidic cells, and (3) dynamic reorientation of microtubules from one system to another.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01282954
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Morphogenetic plastid migration and microtubule organization during megasporogenesis inIsoetes (1989)
    Springer
    Protoplasma 152 (1989), S. 136-147 
    Details
    ISSN: 1615-6102
    Keywords: Isoetes ; Megasporogenesis ; Monoplastidy ; Meiosis ; Microtubules ; Mitotic apparatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The large megasporocytes ofIsoetes provide an exceptional system for studying microtubule dynamics in monoplastidic meiosis where plastid polarity assures coordination of plastid and nuclear division by the intimate association of MTOCs with plastids. Division and migration of the plastid in prophase establishes the tetrahedrally arranged cytoplasmic domains of the future spore tetrad and the four plastid-MTOCs serve as focal points of a unique quadripolar microtubule system (QMS). The QMS is a dynamic structure which functions in plastid deployment and contributes directly to development of both first and second division spindles. The nucleation of microtubules at discrete plastid-MTOCs is compared with centrosomal nucleation of microtubules in animal cells where growth of microtubules involves dynamic instability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01323073
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Microtubule arrays during mitosis in monoplastidic root tip cells ofIsoetes (1992)
    Springer
    Protoplasma 167 (1992), S. 123-133 
    Details
    ISSN: 1615-6102
    Keywords: Confocal ; Isoetes ; Microtubule ; Mitosis ; Monoplastidy ; Plastid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitosis in monoplastidic root tip cells ofIsoetes was studied by fluorescence (confocal laser scanning microscopy) and transmission electron microscopy. The two major components of division polarity, spindle axis and division site, are established more or less simultaneously in preprophase. Morphogenetic plastid migration results in positioning of a daughter plastid at each pole of the future spindle. Concomitant with establishment of the spindle axis, the division site is marked by a girdling band of mirotubules (preprophase band). Endoplasmic microtubules interconnect the polar plastids and preprophase band suggesting a mechanism for communication and final alignment of spindle axis and division site. As in other monoplastidic cells, the spindle appears to emanate from the plastids. In telophase, the focus of microtubules shifts to the reforming nuclei as the phragmoplast is initiated. Microtubules which continue to emanate from plastids are incorporated into the phragmoplast as it expands beyond the interzonal region. Cortical microtubules are restored in a random fashion before assuming a transverse arrangement in interphase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01403375
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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