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  • 1
    Electronic Resource
    Electronic Resource
    Microtubules in Mouse Oocytes, Zygotes, and Embryos during Fertilization and Early Development: Unusual Configurations and Arrest of Mammalian Fertilization with Microtubule Inhibitors (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 466 (1986), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1986.tb38481.x
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  • 2
    Electronic Resource
    Electronic Resource
    Intracellular pH Shift Initiates Microtubule-Mediated Motility during Sea Urchin Fertilization (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 466 (1986), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1986.tb38480.x
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetochore appearance during meiosis, fertilization and mitosis in mouse oocytes and zygotes (1988)
    Springer
    Chromosoma 96 (1988), S. 341-352 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The events of mammalian fertilization overlap with the completion of meiosis and first mitosis; the pronuclei never fuse, instead the parental genomes first intermix at the mitotic spindle equator at metaphase. Since kinetochores are essential for the attachment of chromosomes to spindle microtubules, this study explores their appearance and behavior in mouse oocytes, zygotes and embryos undergoing the completion of meiosis, fertilization and mitoses. Kinetochores are traced with immunofluorescence microscopy using autoimmune sera from patients with CREST (CREST = calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, telangiectasia) scleroderma. These sera cross-react with the 17 kDa centromere protein (CENP-A) and the 80 kDa centromere protein (CENP-B) found at the kinetochores in human cell cultures. The unfertilized oocyte is ovulated arrested at second meiotic metaphase and kinetochores are detectable as paired structures aligned at the spindle equator. At meiotic anaphase, the kinetochores separate and remain aligned at the distal sides of the chromosomes until telophase, when their alignment perpendicular to the spindle axis is lost. The female pronucleus and the second polar body nucleus each receive a detectable complement of kinetochores. Mature sperm have neither detectable centrosomes nor detectable kinetochores, and shortly after sperm incorporation kinetochores become detectable in the decondensing male pronucleus. In pronuclei, the kinetochores are initially distributed randomly and later found in apposition with nucleoli. At mitosis, the kinetochores behave in a pattern similar to that observed at meiosis or mitosis in somatic cells: irregular distribution at prophase, alignment at metaphase, separation at anaphase and redistribution at telophase. They are also detectable in later stage embryos. Colcemid treatment disrupts the meiotic spindle and results in the dispersion of the meiotic chromosomes along the oocyte cortex; the chromosomes remain condensed with detectable kinetochores. Fertilization of Colcemid-treated oocytes results in the incorporation of a sperm which is unable to decondense into a male pronucleus. Remarkably kinetochores become detectable at 5 h post-insemination, suggesting that the emergence of the paternal kinetochores is not strictly dependent on male pronuclear decondensation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00330700
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  • 4
    Electronic Resource
    Electronic Resource
    Activation of maternal centrosomes in unfertilized sea urchin eggs (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 23 (1992), S. 61-70 
    Details
    ISSN: 0886-1544
    Keywords: activation ; fertilization ; microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Centrosomes are undetectable in unfertilized sea urchin eggs, and normally the sperm introduces the cell's microtubule-organizing center (MTOC) at fertilization. However, artificial activation or parthenogenesis triggers microtubule assembly in the unfertilized egg, and this study explores the reappearance and behavior of the maternal centrosome. During activation with A23187 or ammonia, microtubules appear first at the cortex; centrosomal antigen is detected diffusely throughout the entire cytoplasm. Later, the centrosome becomes more distinct and organizes a radial microtubule shell, and eventually a compact centrosome at the egg center organizes a monaster. In these activated eggs, centrosomes undergo cycles of compaction and decompaction in synchrony with the chromatin, which also undergoes cycles of condensation and decondensation. Parthenogenetic activation with heavy water (50% D2O) or the microtubule-stabilizing drug taxol (10 μM) induces numerous centrosomal foci in the unfertilized sea urchin egg. Within 15 min after incubation in D2O, numerous fine centrosomal foci are detected, and they organize a connected network of numerous asters which fill the entire egg. Taxol induces over 100 centrosomal foci by 15 min after treatment, which organize a corresponding number of asters. The centrosomal material in either D2O- or taxol-treated eggs aggregates with time to form fewer but denser foci, resulting in fewer and larger asters. Fertilization of eggs pretreated with either D2O or taxol shows that the paternal centrosome is dominant over the maternal centrosome. The centrosomal material gradually becomes associated with the enlarged sperm aster. These experiments demonstrate that maternal centrosomal material is present in the unfertilized egg, likely as dispersed undetectable material, which can be activated without paternal contributions. At fertilization, paternal centrosomes become dominant over the maternal centrosomal material. © 1992 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970230107
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  • 5
    Electronic Resource
    Electronic Resource
    T-1, a mitotic arrester, alters centrosome configurations in fertilized sea urchin eggs (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 146-154 
    Details
    ISSN: 0886-1544
    Keywords: sea urchin ; centrosome ; immunofluorescence microscopy ; barrel-shaped spindle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: T-1 induces modifications in the shape of the centrosome at division in fertilized eggs of the North American sea urchin, Lytechinus pictus. Phase contrast microscopy observations of mitotic apparatus isolated from T-1treated (1.7-8.5μM) eggs at first division shows that the centrosomes already begin to spread or to separate by prophase and that the mitotic spindle is barrel-shaped. When eggs are fertilized with sperm that have been pretreated with T-1, the centrosomes become flattened; the spindles are of normal length. Immunofluorescence microscopy using an anti-centrosomal monoclonal antibody reveals that T-l modifies the structure of the centrosome so that barrel-shaped spindles with broad centrosomes are observed at metaphase, rather than the expected focused poles and fusiform spindle. Higher concentrations of T-l induce fragmentation of centrosomes, causing abnormal accumulation of microtubules in polar regions. These results indicate that T-l directly alters centrosomal configuration from a compact structure to a flattened or a spread structure. T-l can be classified as a new category of mitotic drugs that may prove valuable in dissecting the molecular nature of centrosomes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970160208
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  • 6
    Electronic Resource
    Electronic Resource
    Dithiothreitol prevents membrane fusion but not centrosome or microtubule organization during the first cell cycles in sea urchins (1994)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 27 (1994), S. 59-68 
    Details
    ISSN: 0886-1544
    Keywords: fertilization ; nucleus ; chromosomes ; cytoskeleton ; mitosis ; sulfhydryl groups ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Dithiothreitol (DTT), a disulfide reducing agent, inhibits the fusion of male and female pronuclei within the activated cytoplasm of sea urchin eggs. The migrations of the pronuclei are not affected by DTT, indicating that microtubule function is not impaired. Centrosomal antigens are detected in the sperm aster and in all subsequent microtubule-based configurations. Nuclear membranes never fuse and the chromatin of male and female pronuclei never mix in the DTT-treated cells. During prophase, when nuclear envelopes break down to undergo mitosis, both sets of chromosomes undergo condensation cycles independent from each other. Both pronuclei initially stain for centrosomal material and surrounding microtubules. With time, the female's centrosomal material as well as the microtubules disappear while the male forms a bipolar spindle. Interestingly, one pole of the paternal mitotic apparatus communicates with the separate maternal chromatin, forming a half spindle which moves the egg-derived chromatin towards its pole. At the time for cell division, the individual karyomeres are not able to fuse their nuclear membranes to reconstitute the blastomere nuclei. When DTT is applied at prometaphase of the first cell cycle, the chromosome cycle continues until next metaphase. Centrosomes also continue their cycle and undergo somewhat atypical splitting during the time for second telophase. Division furrows are initiated but aborted. These results support the hypothesis that disulfide groups are required for membrane fusion of the pronuclei, for membrane fusion of the karyomeres, and for the completion of the division furrow to achieve successful cell division. © 1994 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970270107
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  • 7
    Electronic Resource
    Electronic Resource
    Actin-mediated surface motility during sea urchin fertilization (1983)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 513-524 
    Details
    ISSN: 0886-1544
    Keywords: fertilization ; actin ; microfilaments ; sea urchin ; cell division ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sea urchin egg at fertilization is an ideal model in which to study actin-mediated surface activity. Electron microscopy of unfertilized eggs demonstrates the presence of thousands of well-arrayed short microvilli, which appear supported by cytochalasin-sensitive actin oligomers as detected with rhodamine-labeled phalloidin staining of permeabilized eggs. At insemination, the previously short microvilli elongate and cluster around the successful sperm during incorporation. Phalloidin staining demonstrates a tremendous recruitement of polymerized actin into the site of sperm incorporation, resulting in the formation of the fertilization cone. Fertilization of cytochalasin-treated eggs results in the normal activation of the metabolic and bioeletric events, but sperm incorporation does not occur since the localized actin assembly required for fertilization cone formation is precluded. After sperm incorporation, the entire fertilized surface is restructured, as a result of a massive polymerization of actin to produce a burst in microvillar elongation. Addition of cytochalasin to eggs immediately following sperm incorporation demonstrates the recruitment of actin assembly for the proper progression through the first cell cycle. During normal cell divison, the egg surface retains the long microvilli. The furrow which forms at cytokinesis does not appear as a unique new structure, but rather as a reorganization of the cortical microfilaments. Quantitative fluorescence microscopy argues against an increase in microfilaments during early cytokinesis. At the latest stages of cytokinesis, a thickening of the cortical actin is noted, which could possibly be interpreted as a contractile ring. A minor basal level of actin assembly with numerous nucleation sites in unfertilized eggs and a tremendous but localized assembly of microfilaments surrounding the sperm during incorporation, followed by a massive global microfilament assembly event to elongate the fertilized egg microvilli resulting later in the reorganization of these microfilaments to produce the forces necessary for cytokinesis, highlight the utility of the study of sea urchin eggs at fertilization for understanding actin-membrane interactions.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970030518
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  • 8
    Electronic Resource
    Electronic Resource
    Motility and centrosomal organization during sea urchin and mouse fertilization (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 163-175 
    Details
    ISSN: 0886-1544
    Keywords: centrosomes ; fertilization ; mice ; microfilaments ; microtubules ; mitosis ; pericentriolar material ; sea urchins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Motility and the behavior and inheritance of centrosomes are investigated during mouse and sea urchin fertilization. Sperm incorporation in sea urchins requires microfilament activity in both sperm and eggs as tested with Latrunculin A, a novel inhibitor of microfilament assembly. In contrast the mouse spermhead is incorporated in the presence of microfilament inhibitors indicating an absence of microfilament activity at this stage. Pronuclear apposition is arrested by microfilament inhibitors in fertilized mouse oocytes. The migrations of the sperm and egg nuclei during sea urchin fertilization are dependent on microtubules organized into a radial monastral array, the sperm aster. Microtubule activity is also required during pronuclear apposition in the mouse egg, but they are organized by numerous egg cytoplasmic sites. By the use of an autoimmune antibody to centrosomal material, centrosomes are detected in sea urchin sperm but not in unfertilized eggs. The sea urchin centrosome expands and duplicates during first interphase and condenses to form the mitotic poles during division. Remarkably mouse sperm do not appear to have the centrosomal antigen and instead centrosomes are found in the unfertilized oocyte. These results indicate that both microfilaments and microtubules are required for the successful completion of fertilization in both sea urchins and mice, but at different stages. Furthermore they demonstrate that centrosomes are contributed by the sperm during sea urchin fertilization, but they might be maternally inherited in mammals.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060215
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  • 9
    Electronic Resource
    Electronic Resource
    Microtubules are required for centrosome expansion and positioning while microfilaments are required for centrosome separation in sea urchin eggs during fertilization and mitosis (1988)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 11 (1988), S. 248-259 
    Details
    ISSN: 0886-1544
    Keywords: griseofulvin ; microtubule organizing center ; cell division ; β-mercaptoethanol ; pronuclei ; cytochalasin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Centrosomes undergo cell cycle-dependent changes in shape and separations, changes that govern the organization of the cytoskeleton. The cytoskeleton is largely organized by the centrosome; however, this investigation explores the importance of cytoskeletal elements in directing centrosome shape. Since the sea urchin egg during fertilization and mitosis displays dramatic and synchronous changes in centrosome shape, the effects of cytoskeletal inhibitors on centrosome compaction, expansion, and separation were explored by the use of anticentrosome immunofluorescence microscopy. Centrosome expansion and separation was studied during two phases: the transition after sperm incorporation, when the compact sperm centrosome enlarges and the sperm aster develops, and from prometaphase to telophase, when the compact spindle poles enlarge. Compaction was investigated when the dispersed centrosome at interphase condenses into the two spindle poles at prometaphase. Although centrosome expansion and separation typically occur concurrently, β-mercaptoethanol results in centrosome separation independent of expansion. Microtubule inhibitors prevent centrosome expansion and separation, and expanded centrosomes collapse. Since pronuclear union is arrested by microtubule inhibitors, this treatment also affords the opportunity to explore the relative attractiveness of the male and female pronuclei for these centrosomal antigens. Both pronuclei acquire centrosomal material; though only the male centrosome is capable of organizing a functional bipolar mitotic apparatus at first division, the female centrosome nucleates a monaster. Microfilament inhibition (cytochalasin D) prevents centrosome separation but not expansion or compaction. These results demonstrate that as the centrosome shapes the cytoskeleton, the cytoskeleton alters centrosome shape.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970110404
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  • 10
    Electronic Resource
    Electronic Resource
    Microtubule assembly is required for the formation of the pronuclei, nuclear lamin acquisition, and DNA synthesis during mouse, but not sea urchin, fertillization (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 309-322 
    Details
    ISSN: 0148-7280
    Keywords: pronuclear formation ; microtubules ; microfilaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Microtubule assembly is required for the formation of the male and female pronuclei during mouse, but not sea urchin, fertilization. In mouse oocytes, 50 μM colcemid prevents the decondensation of the maternal meiotic chromosomes and of the incorporated sperm nucleus during in vitro fertilization. Nuclear lamins do not associate with either of the parental chromatin sets although peripherin, the PI nuclear peripheral antigen, appears on both. DN A synthesis docs not occur in these fertilized, colcemid-arrested oocytes. This effect is limited to the first hours after ovulation, since colcemid added 4-6 hours later no longer prevents pronuclear development, lamin acquisition, or DNA synthesis. Neither microtubule stabilization with 10 μM taxol nor microfilament inhibition with 10 μM cytochalasin D or 2.2 μg/ml lalrunculin A prevent these pronuclear events; these drugs will inhibit the apposition of the pronuclei at the egg center. In sea urchin eggs, colcemid or griseofulvin treatment doe? not result in the same effect and the male pronucleus forms with the attendant accumulation of the nuclear lamins. The differences in the requirement for microtubule assembly during pronucleus formation may be related to the cell cycle: In mice the sperm enters a meiotic cytoplasm, whereas in sea urchin eggs it enters an interphase cytoplasm. Refertilization of mitotic sea urchin eggs was performed to test the possibility that this phenomenon is related to whether the sperm enters a meiotic/mitotic cytoplasm or one at interphase; during refertilization at first mitosis, the incorporated sperm nucleus is unable to decondense and acquire lamins. These results indicate a requirement for microtubule assembly for the progression from meiosis to first interphase during mouse fertilization and suggest that the cytoskeleton is required for changes in nuclear architecture necessary during fertilization and the cell cycle.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120230308
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