Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Microtubules  (5)
  • Ultraviolet microbeam  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Transformation of the flagella and associated flagellar components during cell division in the coccolithophoridPleurochrysis carterae (1988)
    Springer
    Protoplasma 145 (1988), S. 37-46 
    Details
    ISSN: 1615-6102
    Keywords: Microtubules ; Basal bodies ; Flagellar apparatus ; Prymnesiophyceae ; Mitosis ; Pleurochrysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Immunofluorescence microscopy, conventional and high voltage transmission electron microscopy were used to describe changes in the flagellar apparatus during cell division in the motile, coccolithbearing cells ofPleurochrysis carterae (Braarud and Fagerlund) Christensen. New basal bodies appear alongside the parental basal bodies before mitosis and at prophase the large microtubular (crystalline) roots disassemble as their component microtubules migrate to the future spindle poles. By prometaphase the crystalline roots have disappeared; the flagellar axonemes shorten and the two pairs of basal bodies (each consisting of one parental and one daughter basal body) separate so that each pair is distal to a spindle pole. By late prometaphase the pairs of basal bodies bear diminutive flagellar roots for the future daughter cells. The long flagellum of each daughter cell is derived from the parental basal bodies; thus, the basal body that produces a short flagellum in the parent produces a long flagellum in the daughter cell. We conclude that each basal body in these cells is inherently identical but that a first generation basal body generates a short flagellum and in succeeding generations it produces a long flagellum. At metaphase a fibrous band connecting the basal bodies appears and the roots and basal bodies reorient to their interphase configuration. By telophase the crystalline roots have begun to reform and the rootlet microtubules have assumed their interphase appearance by early cytokinesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01323254
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Rethinking anaphase: where “Pac-Man” fails and why a role for the spindle matrix is likely (1996)
    Springer
    Protoplasma 192 (1996), S. 1-10 
    Details
    ISSN: 1615-6102
    Keywords: Kinetochore ; Microtubules ; Mitosis ; Pac-Man ; Tensegrity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The “Pac-Man” model for explaining chromosome movement is based on three main tenets: (i) the force that moves chromosomes is generated at the kinetochore; (ii) disassembly of the microtubules (MTs) of the kinetochore fibre generates poleward movement; and (iii) the energy required for this movement comes from MT disassembly. We show that these tenets are not valid in some and perhaps many situations. Thus, the Pac-Man model is inadequate and misleading as the central basis for explaining chromosomal motion generally. We argue that multiple mechanisms are involved in mitotic function and that a contractile/elastic spindle matrix is likely involved not only in anchoring kinetochore fibres, but also by exerting force on them. This view of the spindle matrix shares some features with the “tensegrity” model already formulated as a basis for understanding interphase cell behaviour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01273239
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    The kinetochore fiber structure in the acentric spindles of the green algaOedogonium (1987)
    Springer
    Protoplasma 137 (1987), S. 29-44 
    Details
    ISSN: 1615-6102
    Keywords: Kinetochore fiber ; Microtubules ; Mitosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The microtubule (MT) arrangement in three kinetochore fibers in the acentric spindles of the green algaOedogonium cardiacum were reconstructed from serial sections of prometaphase and metaphase cells. The majority of the MTs attached to the kinetochore (kMTs) are relatively short, extending less than a third of the distance to the putative spindle pole region, and none extended the full distance. Fine filaments and a matrix described earlier (Schibler andPickett-Heaps 1980) were associated with the MTs all along the fibers. Live cells ofOedogonium were also studied by time lapse cinematography for correlation with the ultrastructural observations. Late prometaphase and metaphase kinetochore fibers appear to move independently as if unattached at their poleward ends. These observations suggest that kinetochore fibers inOedogonium are not attached to a specific pole structure from late prometaphase until the inception of anaphase. The results are discussed with reference to spindle structure and function in general.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01281174
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    UV microbeam irradiations of the mitotic spindle I. The UV-microbeam apparatus (1989)
    Springer
    Protoplasma 153 (1989), S. 62-70 
    Details
    ISSN: 1615-6102
    Keywords: Mitosis ; Ultraviolet microbeam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We describe the assembly of a UV microbeam microscope based on a Zeiss IM35 inverted microscope. The important UV transmitting elements are standard UV epifluorescence attachments available from Zeiss; the main modification involves fitting an adjustable slit in place of the field diaphragm. We describe how to align and focus the UV source for optimal irradiations. Our current version of this machine is also fitted with a monochromator and using monochromatic UV light, we can reproduceably create Areas of Reduced Birefringence in spindle fibres with ca. 2–3 s irradiations, while continually observing the fibres. The microscope is stable and easy to set up, allowing many consecutive experiments to be done, including multiple irradiations on the one cell. In conjunction with video image processing techniques, the cells can be observed continuously using polarising, Nomarski or other optical systems. Some preliminary observations demonstrating the versatility of the machine are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01322466
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Cytochalasin D blocks chromosomal attachment to the spindle in the green algaOedogonium (1996)
    Springer
    Protoplasma 192 (1996), S. 130-144 
    Details
    ISSN: 1615-6102
    Keywords: Actin ; Cytochalasin ; Microtubules ; Mitosis ; Spindle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitosis in living cells ofOedogonium observed by time-lapse, was blocked by cytochalasin D (CD; 25–100 μg/ml). Normal prometaphase to anaphase takes 10–15 min; blockage of entry into anaphase by CD was reversible up to 2–2.5 h in CD and washout was followed within 10–20 min by normal anaphase and cytokinesis. After 3–6 h in CD, unseparated chromatids segregated randomly into two groups as the spindle slowly elongated considerably, becoming distorted and twisted. During this “pseudoanaphase”, chromatids sometimes split irregularly and this was stimulated by late washout of CD. CD affected chromosomal attachment to the spindle. If applied at prophase and prometaphase, spindle fibres entered the nucleus; chromosomes moved vigorously and irregularly. A few achieved metaphase only briefly. Treatment at metaphase caused chromosomes to irregularly release and after random movement, all slowly gathered at either pole. Upon removal of CD, chromosomes rapidly achieved metaphase and anaphase A and B soon followed. If CD took effect during anaphase, chromatids detaching from the spindle oscillated rapidly along it; anaphase and cytokinesis (phycoplast formation) were delayed as the cell attempted to correct for abnormal chromosomal behaviour. Thus, CD prevents normal kinetochore attachment to the spindle and actin may be the target for this response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01273885
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Ultraviolet microbeam irradiations of spindle fibres in crane-fly spermatocytes and newt epithelial cells: Resolution of previously conflicting observations (1997)
    Springer
    Protoplasma 197 (1997), S. 230-240 
    Details
    ISSN: 1615-6102
    Keywords: Mitosis ; Ultraviolet microbeam ; Spindle fibres ; Microtubules ; Crane-fly spermatocytes ; Newt epithelial cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In order to resolve apparent differences in reported experiments, we directly compared the effects of ultraviolet (UV) microbeam irradiations on the behaviour of spindle fibres in newt epithelial cells and crane-fly spermatocytes, using the same apparatus for both cell types. This work represents the first time that irradiated crane-fly spermatocytes have been followed using a high-NA objective and video-enhancement of images. In both cell types, irradiation of a kinetochore fibre in metaphase produced an area of reduced birefringence (ARB), known to be devoid of spindle microtubules (MTs). Subsequently the kinetochore-ward edge of the ARB moved poleward with average velocities of 0.5 μm/min (n=20) in spermatocytes and 1.1 μm/min (n=6) in epithelial cells. The poleward edge of the ARB rapidly disappeared when viewed using a ×100, high-NA objective but generally remained visible when viewed with a ×32, low-NA objective; this difference suggests that MTs poleward from the ARB disperse vertically out of the narrow depth of field of the ×100 objective but that many remain encompassed by that of the ×32 objective. The primary difference in response between the two cell types was in the behaviour of the spindle poles after an ARB formed. In spermatocytes the spindle maintained its original length whereas in epithelial cells the pole on the irradiated side very soon moved towards the chromosomes, after which the other pole did the same and a much shortened functional metaphase spindle was formed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01288032
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...