The ultrastructure and spatial organization of the metaphase kinetochore in mitotic rat cells

Jokelainen, Pentti T.

doi:10.1016/s0022-5320(67)80058-3

Cited by 198 publications

(96 citation statements)

References 36 publications

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“…The kinetochore's critical role in chromo-some segregation has led extensive investigations of kinetochore function in a wide range of organisms and model systems (Rieder and Salmon 1998;Cleveland et al 2003;Maiato et al 2004a;Chan et al 2005). Classical EM studies led to the view that the kinetochore in vertebrates resembles a trilaminar disk (Brinkley and Stubblefield 1966;Jokelainen 1967;Roos 1973Roos , 1977Rieder 1982). In this model, an electron-dense inner plate is located on the surface of the centromeric heterochromatin and it is separated from an electron-dense outer plate by a lighter middle layer.…”

Section: Introductionmentioning

confidence: 99%

The ultrastructure of the kinetochore and kinetochore fiber in Drosophila somatic cells

et al. 2006

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Drosophila melanogaster is a widely used model organism for the molecular dissection of mitosis in animals. However, despite the popularity of this system, no studies have been published on the ultrastructure of Drosophila kinetochores and kinetochore fibers (K-fibers) in somatic cells. To amend this situation, we used correlative light (LM) and electron microscopy (EM) to study kinetochores in cultured Drosophila S2 cells during metaphase, and after colchicine treatment to depolymerize all microtubules (MTs). We find that the structure of attached kinetochores in S2 cells is indistinct, consisting of an amorphous inner zone associated with a more electron-dense peripheral surface layer that is approximately 40-50 nm thick. On average, each S2 kinetochore binds 11±2 MTs, in contrast to the 4-6 MTs per kinetochore reported for Drosophila spermatocytes. Importantly,

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Section: Introductionmentioning

confidence: 99%

The ultrastructure of the kinetochore and kinetochore fiber in Drosophila somatic cells

et al. 2006

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“…Structurally, the kinetochore is composed of four layers: an innermost plate that apparently consists of a specialized layer of chromatin, an interzone, an outer plate that has been argued to consist of tightly packed fibers [4,5], and an outermost fuzzy, fibrous corona that is most clearly seen after microtubule disassembly [6,7]. Although kinetochore morphology has been documented in numerous ultrastructural studies [8][9][10][11][12], there is little information about molecular composition and the respective localization of known kinetochore proteins or protein complexes, except for a handful kinetochore proteins such as CENP-A (attached to to centromeric heterochromatin) [13], CENP-B (underneath the inner plate) [14], CENP-C (a component of the inner plate [1], CENP-E [a component of the corona fiber) [ 7], CENP-F (a component of outer plate) [15], Bub1 and BubR1 [components of the corona fiber) [16].…”

Section: Introductionmentioning

confidence: 99%

Dynamic distribution of TTK in HeLa cells: insights from an ultrastructural study

et al. 2003

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Entry into mitosis is driven by signaling cascades of mitotic kinases. Our recent studies show that TTK, a kinetochore-associated protein kinase, interacts with CENP-E, a mitotic kinesin located to corona fiber of kinetochore. Using immunoelectron microscopy, here we show that TTK is present at the nuclear pore adjacent complex of interphase HeLa cells. Upon nuclear envelope fragmentation, TTK targets to the outermost region of the developing kinetochores of monoorient chromosome as well as to spindle poles. After stable attachment, throughout chromosome congression, TTK is a constituent of the corona fibers, extending up to 90 nm away from the kinetochore outer plate. Upon metaphase alignment, TTK departs from the kinetochore and migrates toward the centrosomes. Taken together, this evidence strongly supports a model in which TTK functions in spindle checkpoint signaling cascades at both kinetochore and centrosome.

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“…In sections from conventionally fixed and stained vertebrate somatic cells unattached kinetochores are seen to consist of a circular 35-40 nm thick electron-opaque platelike structure that consists of a dense meshwork of 10-20 nm thick fibers (reviewed in Jokelainen 1967;Rieder 1982;McEwen et al 1993;Cooke et al 1997;Yao et al 1997). This plate is separated from the underlying centromeric heterochromatin by a 15-30 nm thick electron-lucent zone relatively devoid of structure.…”

Section: Introductionmentioning

confidence: 99%

“…A conspicuous fine fibrillar corona material radiates 100 nm or more from the cytoplasmic surface of the plate, which can vary significantly in diameter between the chromosomes of a genome (but is only weakly correlated with chromosome size; see . As this kinetochore plate attaches to Mt ends the corona becomes less distinct (reviewed in Rieder 1982;Cassimeris et al 1990), its diameter decreases significantly (see Jokelainen 1967;reviewed in Rieder 1982), and a dense staining inner plate appears in association with the surface of the chromatin underlying the Mt-binding outer plate (see Rieder 1979Rieder , 1982.…”

Section: Introductionmentioning

confidence: 99%

“…Many of these schemes ascribe different functional roles to each of the three structural domains that form the kinetochore. However, our concept of kinetochore structure is based entirely on fixation procedures developed more than 30 years ago (e.g., see Brinkley and Stubblefield 1966;Jokelainen 1967) that are known to extract the cytoplasmic components and induce subtle and even not so subtle structural changes. Indeed, although largely ignored when interpreting kinetochore structure, chromosomes in cells fixed by conventional buffered glutaraldehyde/ osmium protocols shrink up to 9% in width and length during the dehydration process (Jensen and Bajer 1969).…”

Section: Introductionmentioning

confidence: 99%

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A new look at kinetochore structure in vertebrate somatic cells using high-pressure freezing and freeze substitution

et al. 1998

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Three decades of structural analysis have produced the view that the kinetochore in vertebrate cells is a disk-shaped structure composed of three distinct structural domains. The most prominent of these consists of a conspicuous electron opaque outer plate that is separated by a light-staining electrontranslucent middle plate from an inner plate associated with the surface of the pericentric heterochromatin. Spindle microtubules terminate in the outer plate and, in their absence, a conspicuous corona of fine filaments radiates from the cytoplasmic surface of this plate. Here we report for the first time the ultrastructure of kinetochores in untreated and Colcemid-treated vertebrate somatic (PtK 1 ) cells prepared for optimal structural preservation using high-pressure freezing and freeze substitution. In serial thin sections, and electron tomographic reconstructions, the kinetochore appears as a 50-75 nm thick mat of light-staining fibrous material that is directly connected with the more electron-opaque surface of the centromeric heterochromatin. This mat corresponds to the outer plate in conventional preparations, and is surrounded on its cytoplasmic surface by a conspicuous 100-150 nm wide zone that excludes ribosomes and other cytoplasmic components. High magnification views of this zone reveal that it contains a loose network of light-staining, thin (<9 nm diameter) fibers that are analogous to the corona fibers in conventional preparations. Unlike the chromosome arms, which appear uniformly electron opaque, the chromatin in the primary constriction appears mottled. Since the middle plate is not visible in these kinetochore preparations this feature is likely an artifact produced by extraction and coagulation during conventional fixation and/or dehydration procedures.

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The ultrastructure and spatial organization of the metaphase kinetochore in mitotic rat cells

Cited by 198 publications

References 36 publications

The ultrastructure of the kinetochore and kinetochore fiber in Drosophila somatic cells

The ultrastructure of the kinetochore and kinetochore fiber in Drosophila somatic cells

Dynamic distribution of TTK in HeLa cells: insights from an ultrastructural study

A new look at kinetochore structure in vertebrate somatic cells using high-pressure freezing and freeze substitution

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