Mechanical Torque Promotes Bipolarity of the Mitotic Spindle Through Multi-centrosomal Clustering

Christopher E. Miles; Jie Zhu; Alex Mogilner

doi:10.1007/s11538-021-00985-2

Structural Studies on Mitotic Spindle Fibres

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100070345 ◽

1978 ◽

Vol 36 (3) ◽

pp. 615-626

Author(s):

J.R. Mcintosh

Keyword(s):

Chemical Composition ◽

Mitotic Spindle ◽

Structural Studies ◽

Mitotic Apparatus ◽

Chemical Studies ◽

Medical Interest ◽

Spindle Fibres

The mitotic apparatus is a structure of obvious biological and medical interest, but it has proved to be a difficult cellular machine to understand. The chemical composition of the spindle is only slightly elucidated, largely because of the difficulties in preparing useful isolates of the structure. Chemical studies of the mitotic spindle have been reviewed elsewhere (Mcintosh, 1977), and will not be discussed further here. One would think that structural studies on the mitotic apparatus (MA) in situ would be straightforward, but even with this approach there is some disagreement in the results obtained with various methods and by different investigators. In this paper I will review briefly the approaches which have been used in structural studies of the MA, pointing out the strengths and problems of each approach. I will summarize the principal findings of the different methods, and identify what seem to be fruitful avenues for further work.

Download Full-text

Filaments and membranes in the mitotic apparatus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010007638x ◽

1983 ◽

Vol 41 ◽

pp. 544-547

Author(s):

Kent McDonald

Keyword(s):

Intermediate Filaments ◽

Mitotic Spindle ◽

Mitotic Apparatus ◽

Light Microscope Level ◽

Microtubule Associated Proteins ◽

Recent Developments ◽

Associated Proteins ◽

Force Generator ◽

Spindle Function ◽

Antibody Technology

At the light microscope level the recent developments and interest in antibody technology have permitted the localization of certain non-microtubule proteins within the mitotic spindle, e.g., calmodulin, actin, intermediate filaments, protein kinases and various microtubule associated proteins. Also, the use of fluorescent probes like chlorotetracycline suggest the presence of membranes in the spindle. Localization of non-microtubule structures in the spindle at the EM level has been less rewarding. Some mitosis researchers, e.g., Rarer, have maintained that actin is involved in mitosis movements though the bulk of evidence argues against this interpretation. Others suggest that a microtrabecular network such as found in chromatophore granule movement might be a possible force generator but there is little evidence for or against this view. At the level of regulation of spindle function, Harris and more recently Hepler have argued for the importance of studying spindle membranes. Hepler also believes that membranes might play a structural or mechanical role in moving chromosomes.

Download Full-text

Quantitative ultrastructural reconstruction of small regions within large volumes by correlative light and high voltage electron microscopy of serial 0.25-0.50 μm sections

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100127396 ◽

1987 ◽

Vol 45 ◽

pp. 578-581

Author(s):

Conly L. Rieder ◽

Frederick J. Miller ◽

Edwin Davison ◽

Samuel S. Bowser ◽

Kirsten Lewis ◽

...

Keyword(s):

Electron Microscopy ◽

High Voltage ◽

Mitotic Spindle ◽

Meiotic Spindle ◽

High Voltage Electron Microscopy ◽

Male And Female ◽

Voltage Electron ◽

High Voltage Electron ◽

Differential Stability ◽

Sperm Aster

In this abstract we Illustrate how same-section correlative light and high voltage electron microscopy (HVEM) of serial 0.25-0.50-μm sections can answer questions which are difficult to approach by EM of 60-100 nm sections.Starfish (Pisaster and Asterlas) eggs are fertilized at meiosis I when the oocyte contains two maternal centrosomes (e.g., asters) which form the poles of the first meiotic spindle. Immediately after fertilization a sperm aster is assembled in the vicinity of the male pronucleus and persists throughout meiosis. At syngamy the sperm aster splits to form the poles of the first mitotic spindle. During this time the functional and replicative properties of the maternal centrosome, inherited from the last meiotic division, are lost. The basis for this differential stability, of male and female centrosomes in the same cytoplasm, is a mystery.

Download Full-text

Modulated polarization microscopy displays the dynamics of cytoskeletal structures in living, motile cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100140889 ◽

1995 ◽

Vol 53 ◽

pp. 902-903

Author(s):

J. R. Kuhn ◽

M. Poenie

Keyword(s):

Mitotic Spindle ◽

Actin Filaments ◽

Cell Shape ◽

Dynamic Structure ◽

Living Cells ◽

Cytoskeletal Proteins ◽

Polarization Microscopy ◽

Video Enhancement ◽

Ultrastructural Studies ◽

Motile Cells

Cell shape and movement are controlled by elements of the cytoskeleton including actin filaments an microtubules. Unfortunately, it is difficult to visualize the cytoskeleton in living cells and hence follow it dynamics. Immunofluorescence and ultrastructural studies of fixed cells while providing clear images of the cytoskeleton, give only a static picture of this dynamic structure. Microinjection of fluorescently Is beled cytoskeletal proteins has proved useful as a way to follow some cytoskeletal events, but long terry studies are generally limited by the bleaching of fluorophores and presence of unassembled monomers.Polarization microscopy has the potential for visualizing the cytoskeleton. Although at present, it ha mainly been used for visualizing the mitotic spindle. Polarization microscopy is attractive in that it pro vides a way to selectively image structures such as cytoskeletal filaments that are birefringent. By combing ing standard polarization microscopy with video enhancement techniques it has been possible to image single filaments. In this case, however, filament intensity depends on the orientation of the polarizer and analyzer with respect to the specimen.

Download Full-text

3-D reconstruction and analysis of mammalian mitotic spindle structure

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100123295 ◽

1992 ◽

Vol 50 (1) ◽

pp. 578-579

Author(s):

Kent McDonald ◽

David Mastronarde ◽

Rubai Ding ◽

Eileen O'Toole ◽

J. Richard McIntosh

Keyword(s):

Cross Sections ◽

Mitotic Spindle ◽

Experimental Studies ◽

Video Camera ◽

Three Dimensions ◽

Mitotic Spindles ◽

Black And White ◽

Reconstruction Methods ◽

Spindle Structure ◽

Tissue Culture Line

Mammalian spindles are generally large and may contain over a thousand microtubules (MTs). For this reason they are difficult to reconstruct in three dimensions and many researchers have chosen to study the smaller and simpler spindles of lower eukaryotes. Nevertheless, the mammalian spindle is used for many experimental studies and it would be useful to know its detailed structure.We have been using serial cross sections and computer reconstruction methods to analyze MT distributions in mitotic spindles of PtK cells, a mammalian tissue culture line. Images from EM negatives are digtized on a light box by a Dage MTI video camera containing a black and white Saticon tube. The signal is digitized by a Parallax 1280 graphics device in a MicroVax III computer. Microtubules are digitized at a magnification such that each is 10-12 pixels in diameter.

Download Full-text

Laser Scanning Confocal Microscopy and Three-Dimesnsional Reconstruction of the Mitotic Spindles of Unequally Dividing Embryonic Cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100158376 ◽

1990 ◽

Vol 48 (3) ◽

pp. 166-167

Author(s):

J. Holy ◽

G. Schatten

Keyword(s):

Confocal Microscopy ◽

Mitotic Spindle ◽

Laser Scanning ◽

Three Dimensional ◽

Laser Scanning Confocal Microscopy ◽

Two Dimensions ◽

Embryonic Cells ◽

Mitotic Spindles ◽

Cleavage Division ◽

Scanning Confocal Microscopy

One of the classic limitations of light microscopy has been the fact that three dimensional biological events could only be visualized in two dimensions. Recently, this shortcoming has been overcome by combining the technologies of laser scanning confocal microscopy (LSCM) and computer processing of microscopical data by volume rendering methods. We have employed these techniques to examine morphogenetic events characterizing early development of sea urchin embryos. Specifically, the fourth cleavage division was examined because it is at this point that the first morphological signs of cell differentiation appear, manifested in the production of macromeres and micromeres by unequally dividing vegetal blastomeres.The mitotic spindle within vegetal blastomeres undergoing unequal cleavage are highly polarized and develop specialized, flattened asters toward the micromere pole. In order to reconstruct the three-dimensional features of these spindles, both isolated spindles and intact, extracted embryos were fluorescently labeled with antibodies directed against either centrosomes or tubulin.

Download Full-text