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  • 1
    Electronic Resource
    Electronic Resource
    On the mechanism of prometaphase congression: Chromosome velocity as a function of position on the spindle (1978)
    Springer
    Chromosoma 69 (1978), S. 231-241 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Rates of movement of univalents at prometaphase and of half-bivalents at anaphase in living cricket and grasshopper spermatocytes were determined as a function of the distance from the pole toward which the movement was directed. In the artificially produced univalents of cricket cells, correlation coefficients for rate versus distance form the pole were widely disparate from movement to movement and there was no consistent relationship between velocity and distance from the pole. However, in the naturally occurring univalents of grasshopper cells, there was a significant positive correlation between velocity and distance from the pole. In both cricket and grasshopper cells, there was no consistent correlation between rate of movement and distance from the pole for half-bivalents at anaphase. The prometaphase data from grasshopper cells support the simple hypothesis of Östergren (1950) that congression results from the application to chromosomes of forces which increase with increasing distance from the pole. Furthermore, these data are consistent with models of force production which suppose that the relationship between force (reflected as velocity) and distance from the pole is a linear one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00329921
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  • 2
    Electronic Resource
    Electronic Resource
    A quadrivalent studied in living and fixed grasshopper spermatocytes (1977)
    Springer
    Chromosoma 63 (1977), S. 305-315 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A single specimen of the grasshopper Melanoplus differentialis was discovered which was heterozygous for an interchange involving two of the largest chromosomes of the complement. The resulting quadrivalent occurred as a ring-of-four, chain-of-four, and, rarely, as two heteromorphic bivalents. Metaphase orientation and anaphase disjunction of some of these quadrivalents were recorded in living cells. The chain-of-four was stable in the configuration in which two pairs of kinetochores were oriented to each pole. The configuration in which three pairs of kinetochores were oriented to one pole and one pair to the other pole was also stable, but was shifted off the equator toward the pole to which three pairs of kinetochores were oriented. Given the nature of this quadrivalent the unusual stability of the 3∶1 configuration is expected from current hypotheses of chromosome orientation and reorientation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00399493
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  • 3
    Electronic Resource
    Electronic Resource
    A calcium-rich intraspindle membrane system in spermatocytes of wolf spiders (1984)
    Springer
    Chromosoma 90 (1984), S. 156-161 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The meiotic spindle of spermatocytes of two wolf spiders contains a highly organized system of ER-like membranes. In cells observed ultrastructurally at early prometaphase, these membranes completely invest each bivalent and are present in the periphery of the spindle in association with the centrosomes. By metaphase each bivalent and its kinetochore fibers are completely encased in a tube of this membrane. We have treated living spermatocytes with the permeant, fiuorescent-chelate probe, chlorotetracycline (CTC) to determine whether or not the intraspindle membrane system is rich in associated Ca2+. Spider testes were dissected into PIPES-buffered saline containing 200 μM CTC and were kept in this solution for 10 min. Autofluorescence controls were prepared by incubation in saline without CTC, and nonspecific effects of CTC were assessed by incubation for 10 min in 200 μM oxytetracycline (OTC). Neither unstained nor OTC-treated spermatocytes emit significant fluorescence. In contrast, CTC treatment yields bright, punctate fluorescence, which coincides with the distribution of the mitochondria. The plasma membrane is only weakly fluorescent, while the nuclear envelope exhibits prominent fluorescence. The chromosomes are not fluorescent during prophase, but after nuclear envelope breakdown, they become outlined by dim, but distinct fluorescence. As spindle formation commences, the CTC signal from the intraspindle membrane system becomes strong. In some cells, thin lines of CTC fluorescence are apparent in the metaphase half spindle; this fluorescence pattern mimics the distribution of the intraspindle membrane system and suggests that it is rich in associated Ca2+. We suggest that the intraspindle membrane system functions in the regulation of cytosolic Ca2+during meiosis through sequestration of the cation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292453
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  • 4
    Electronic Resource
    Electronic Resource
    The ultrastructure of an intraspindle membrane system in meiosis of spider spermatocytes (1984)
    Springer
    Chromosoma 90 (1984), S. 50-56 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract An extensive system of membranes was found in the spindles of spermatocytes of two wolf spider species, Lycosa georgicola and L. rabida. Serial section reconstructions of this membrane system revealed that each meiotic bivalent is encased in a tube of membrane, which encloses both kinetochore microtubule bundles and approaches to within a few microns of the centriolar complex. The membrane tube is open at the polar ends. The membrane composing the tube is doubled and resembles smooth endoplasmic reticulum (ER). No evidence of nuclear pore complexes has been found in the intraspindle membrane system, but typical pores are present on the nuclear envelope of prophase cells. The membrane tubes are fenestrated and microtubules sometimes penetrate these fenestrae. Besides its possible function in the regulation of chromosome movement, the intraspindle membrane system may participate in the nonrandom segregation of the sex chromosomes at meiosis in these spiders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00352278
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  • 5
    Electronic Resource
    Electronic Resource
    Random distribution of centromere regions at mitosis in cultured cells of Muntiacus muntjak (1976)
    Springer
    Chromosoma 55 (1976), S. 69-74 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The manner in which centromere regions of mitotic chromosomes are distributed with respect to the age of their DNA was studied. Cells of the Indian deer, Muntiacus muntjak, were grown in the presence of bromodeoxyuridine (BrdU) for two generations and stained with the fluorescent dye Hoechst 33258. Chromatids containing “granddaughter DNA” appear dim when compared with those containing “grandparental DNA”. The frequencies of the various anaphase patterns of bright and dim centromere regions were binomially distributed, indicating random distribution of chromatids with respect to the age of their DNA templates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00288328
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  • 6
    Electronic Resource
    Electronic Resource
    Chromosome fiber dynamics and congression oscillations in metaphase PtK2 Cells at 23°C (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 18 (1991), S. 131-142 
    Details
    ISSN: 0886-1544
    Keywords: mitosis ; microtubules ; tubulin incorporation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A bioriented chromosome is tethered to opposite spindle poles during congression by bundles of kinetochore microtubules (kMts). At room temperature, kinetochore fibers are a dominant component of mitotic spindles of PtK2 cells. PtK2 cells at room temperature were injected with purified tubulin covalently bound to DTAF and congression movements of individual chromosomes were recorded in time lapse. Congression movements of bioriented chromosomes between the poles occur over distances of 4.5 μm or greater. DTAF-tubulin injection had no effect on either the velocity or extent of these movements. Other cells were lysed, fixed, and the location of DTAF-tubulin incorporation was detected from digitally processed images of indirect immunofluorescence of an antibody to DTAF. Microtubules were labeled with an anti-beta tubulin antibody. At 2-5 minutes after injection, concentrated DTAF-tubulin staining was seen in the kinetochore fibers proximal to the kinetochores; a low concentration of DTAF-tubulin staining occurred at various sites through the remaining length of the fibers toward the pole. Kinetochore fibers in the same cell displayed different lengths (0.2 to 4 μm) of concentrated DTAF-tubulin incorporation proximal to the kinetochore, as did sister kinetochore fibers. Ten minutes after injection, the lengths of DTAF-containing chromosomal fibers were greater than expected if incorporation resulted solely from the lengthening of kinetochore microtubules due to congression movements of the chromosomes. Besides incorporation as a result of chromosome movement, two other mechanisms might explain the length of the DTAF-containing segments: (1) a poleward flux of tubulin subunits (Mitchison, 1989) or (2) capture of DTAF-containing nonkinetochore microtubules.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970180208
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  • 7
    Electronic Resource
    Electronic Resource
    Antikinetochore antibodies interfere with prometaphase but not anaphase chromosome movement in living PtK2 cells (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 23 (1992), S. 157-167 
    Details
    ISSN: 0886-1544
    Keywords: mitosis ; scleroderma antiserum ; kinetochore ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Injection of CREST antikinetochore antiserum (AKA) containing antibodies to the kinetochore into living prometaphase PtK2 cells decreased chromosome velocity to near zero. Injection of either phosphate-buffered saline or CREST antiserum without antikinetochore antibodies (antikinetochore negative: AKN) had no effect on prometaphase oscillations. AKA antiserum injected into anaphase cells at the beginning of chromatid separation had no effect on anaphase chromosome velocity, spindle elongation, or cytokinesis. Visible binding of antikinetochore antibodies in prometaphase cells at room temperature occurred between 5 and 15 minutes after injection. Anaphase cells injected at the beginning of chromatid separation had bound antibody at the end of anaphase. AKA antiserum recognizes in Western blots proteins associated with the primary constriction: CENP-B, -C, and -D, as reported by other workers. The control antiserum, AKN, does not recognize these proteins. These results imply that the antigens recognized by CREST antibodies are important for chromosome movement. Whether or not these antigens are themselves motor molecules cannot be addressed by the present data. In addition, the results suggest that these antigens are not involved in an important way in anaphase movement. © 1992 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970230208
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  • 8
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    A quadrivalent studied in living and fixed grasshopper spermatocytes (1977)
    Springer
    Details
    Publication Date: 1977-01-01
    Print ISSN: 0009-5915
    Electronic ISSN: 1432-0886
    Topics: Biology , Medicine
    Published by Springer
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  • 9
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    The ultrastructure of an intraspindle membrane system in meiosis of spider spermatocytes (1984)
    Springer
    Details
    Publication Date: 1984-06-01
    Print ISSN: 0009-5915
    Electronic ISSN: 1432-0886
    Topics: Biology , Medicine
    Published by Springer
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  • 10
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    A calcium-rich intraspindle membrane system in spermatocytes of wolf spiders (1984)
    Springer
    Details
    Publication Date: 1984-08-01
    Print ISSN: 0009-5915
    Electronic ISSN: 1432-0886
    Topics: Biology , Medicine
    Published by Springer
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