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  • Articles  (132)
  • fertilization  (132)
  • Wiley-Blackwell  (132)
  • American Geophysical Union
  • Biology  (132)
  • 1
    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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  • 2
    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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  • 3
    Electronic Resource
    Electronic Resource
    Microtubules in ascidian eggs during meiosis, fertilization, and mitosis (1988)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 9 (1988), S. 219-230 
    Details
    ISSN: 0886-1544
    Keywords: fertilization ; ooplasmic segregation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sequential changes in the distribution of microtubules during germinal vesicle breakdown (GVBD), fertilization, and mitosis were investigated with antitubulin indirect immunofluorescence microscopy in several species of ascidian eggs (Molgula occidentalis, Ciona savignyi, and Halocynthia roretzi). These alterations in microtubule patterns were also correlated with observed cytoplasmic movements. A cytoplasmic latticework of microtubules was observed throughout meiosis. The unfertilized egg of M. occidentalis had a small meiotic spindle with wide poles; the poles became focused after egg activation. The other two species had more typical meiotic spindles before fertilization. At fertilization, a sperm aster first appeared near the cortex close to the vegetal pole. It enlarged into an unusual asymmetric aster associated with the egg cortex. The sperm aster rapidly grew after the formation of the second polar body, and it was displaced as far as the equatorial region, corresponding to the site of the myoplasmic rescent, the posterior half of the egg. The female pronucleus migrated to the male pronucleus at the center of the sperm aster. The microtubule latticework and the sperm aster disappeared towards the end of first interphase with only a small bipolar structure remaining until first mitosis. At mitosis the asters enlarged tremendously, while the mitotic spindle remained remarkably small. The two daughter nuclei remained near the site of cleavage even after division was complete. These results document the changes in microtubule patterns during maturation in Ascidian oocytes, demonstrate that the sperm contributes the active centrosome at fertilization, and reveal the presence of a mitotic apparatus at first division which has an unusually small spindle and huge asters.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970090304
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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
    Redistribution of actin and fascin in sea urchin eggs after fertilization (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 31-40 
    Details
    ISSN: 0886-1544
    Keywords: actin ; fascin ; actin cross-linking proteins ; fertilization ; microvilli ; sea urchin eggs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Following fertilization, the sea urchin egg cortex undergoes a structural change involving the assembly and organization of actin filaments into microvilli. Antifascin localizes this actin cross-linking protein in the microvilli of the fertilized egg cortex but no organized staining is present in the unfertilized cortex. Determination of the actin content of eggs using the DNAase I inhibition assay indicates that actin is about 1.4% of the total protein. Approximately 90% of this actin is soluble in low calcium isotonic extracts of unfertilized eggs while only 60-65% can be recovered in identical extracts of fertilized eggs. Similar measurements for fascin using a radioimmunoassay indicate this molecule represents about 0.3% of the total egg protein, essentially all of which is recovered in low calcium isotonic extracts of unfertilized eggs. After fertilization only 65-70% of this actin cross-linking protein is in the soluble phase. These results demonstrate a markedly different solubility for actin and fascin after fertilization, when the indirect immunofluorescence staining localizes fascin in the microvilli, and are consistent with the idea that fascin organizes newly polymerized actin filaments into the microvillar cores. A consideration of the amounts of actin and fascin incorporated into the cortex after fertilization and the number of microvilli on the egg surface indicates that the measured values are sufficient to account for the observed microvillar elongation.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010104
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  • 6
    Electronic Resource
    Electronic Resource
    Wave of cortical actin polymerization in the sea urchin egg (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 46-53 
    Details
    ISSN: 0886-1544
    Keywords: actin filament ; fertilization ; fluorescent labeled phallotoxins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution of actin filaments in the cortical layer of sea urchin eggs during fertilization has been investigated by light microscopy using fluorescently labeled phallotoxins. The cortical layer of both whole eggs and cortices isolated on a glass surface was examined. In cortices of unfertilized eggs, numerous fluorescent spots were seen, which may correspond to short actin filament cores in microvilli. After insemination, one of the sperm-attaching points on the egg surface first became strongly fluorescent. This fluorescence grew around the point of sperm penetration with the growth of the fertilization cone. Then, the cortical layer of the egg around the fertilization cone became strongly fluorescent and the fluorescence propagated in a wavelike manner over the entire cortex. The mechanism of the propagation of actin polymerization is discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970070107
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  • 7
    Electronic Resource
    Electronic Resource
    Unfertilized sea urchin eggs contain a discrete cortical shell of actin that is subdivided into two organizational states (1988)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 9 (1988), S. 85-96 
    Details
    ISSN: 0886-1544
    Keywords: fertilization ; echinoderm eggs ; egg cortex ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Changes in the distribution and organizational state of actin in the cortex of echinoderm eggs are believed to be important events following fertilization. To examine the initial distribution and form of actin in unfertilized eggs, we have adapted immunogold-labeling procedures for use with eggs of Strongylocentrotus purpuratus. Using these procedures, as well as fluorescence microscopy, we have revealed a discrete 1-μm-thick concentrated shell of actin in the unfertilized egg cortex. This actin is located in the short surface projections of unfertilized eggs and around the cortical granules in a manner that suggests it is associated with the cortical granule surface. The actin in the short surface projections appears to be organized into filaments. However, most if not all of the actin surrounding the cortical granules is organized in a form that does not bind phalloidin, even though it is accessible to actin antibody. The lack of phalloidin binding is consistent with either the presence of nonfilamentous actin associated with the cortical granules or the masking of actin-filament phalloidin-binding sites by some cellular actin-binding component. In addition to the concentrated shell of actin found in the cortex, actin was also found to be concentrated in the nuclei of unfertilized eggs.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970090109
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  • 8
    Electronic Resource
    Electronic Resource
    Wave of free calcium at fertilization in the sea urchin egg visualized with fura-2 (1988)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 9 (1988), S. 271-277 
    Details
    ISSN: 0886-1544
    Keywords: fertilization ; Ca2+ wave ; fura-2 ; sea urchin egg ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A wave front of increased free calcium traversing the egg at fertilization is demonstrated in the sea urchin Lytechinus pictus. The use of the fluorescent calcium chelator fura-2 in combination with low-light-level TV microscopy and image processing allows the visualization of the Ca2+ wave front with high spatial and temporal resolution. Such a wave is demonstrated as increased fluorescence after an excitation of 340-nm wavelength and as the reciprocal image in form of a reduced fluorescence when excited at 380 nm. The band-like appearance of the wave resembles the Ca2+ wave described for larger eggs of other species. In a dispermic egg the high resolution of the system used allows us to recognize two waves of Ca2+ originating from the respective points of sperm entry.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970090309
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  • 9
    Electronic Resource
    Electronic Resource
    A 70 kD microtubule-binding protein from starfish eggs: Purification, characterization, and localization during meiosis and mitosis (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 168-180 
    Details
    ISSN: 0886-1544
    Keywords: microtubule-associated proteins (MAPs) ; taxol ; oocyte maturation ; fertilization ; cell division ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A microtubule-binding protein was purified from eggs of the starfish, Asterias amurensis, through several steps of purification including the taxol-dependent procedure [Vallee, 1982, J. Cell Biol. 92:435-442]. This protein consists of a single polypeptide chain having an apparent molecular mass of 70 kD determined by SDS-PAGE. The 70 kD protein was identified as a unique microtubulebinding protein, judging from electrophoretic mobility, cleavage pattern by limited proteolysis, heat stability, and immunocrossreactivity. The 70 kD protein binds to brain and egg microtubules. It does not promote assembly of brain tubulin, but promotes that of egg tubulin in vitro in a concentration-dependent manner.Using indirect immunofluorescence and immunoelectron microscopy with the anti-70 kD protein antibody, we analyzed the cellular localization of the 70 kD protein in starfish oocytes and eggs during both meiotic maturation (meicsis) and first cleavage (mitosis). Immunofluorescence studies showed that the 70 kD protein localized on microtubule structures spread widely throughout the cytoplasm, the sperm aster, and the microtubules making up the mitotic apparatus through both meiosis and mitosis. The antibody, however, did not recognize sperm axonemes. These results were confirmed by immunoelectron microscopy. Using a colloidal gold technique, the 70 kD protein was localized along the microtubules in vivo.This 70 kD protein is the first microtubule-binding protein that has been shown to localize along the microtubules in oocytes and eggs throughout meiosis and mitosis and to promote microtubule assembly. The 70 kD protein may be involved in the dynamic changes of microtubule structures occurring within oocytes and eggs.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970150306
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  • 10
    Electronic Resource
    Electronic Resource
    Microtubule-containing detergent-extracted cytoskeletons in sea urchin eggs from fertilization through cell division: Antitubulin immunofluorescence microscopy (1983)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 213-226 
    Details
    ISSN: 0886-1544
    Keywords: microtubules ; fertilization ; cell division ; sea urchin ; cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The microtubule-containing structures that appear in eggs during fertilization and cell division in the sea urchins Lytechinus variegatus and Arbacia punctulata were detected by antitubulin immunofluorescence microscopy of detergent extracted cytoskeletal preparations. The extraction buffer, which is composed of 0.55 mM MgCl2, 10 mM EGTA, 25 mM MES, 25% glycerol, 1% Nonidet P-40, and 25 μM PMSF, pH 6.7, allows for dramatically improved fluorescent images compared to those obtained using conventional staining procedures, with residual background staining being reduced to near zero.The immunofluorescent images obtained using this technique provide information on several motile events that occur during the first cell cycle. This technique demonstrates that all of the cytoplasmic microtubules are associated with the incorporated sperm's centrioles during female pronuclear migration. This changes during the centration of the male and female pronuclei at which time a monastral array of microtubules forms in the egg's cytoplasm. A large proportion of the monastral microtubules do not appear to be associated with the centrioles. At prophase and early metaphase, the centrioles are the dominant microtubule organizing centers (MTOCs) consistent with mitotic theories that the kinetochore catches, but does not initiate, microtubules. Observations of intercentriolar distances show that there are three stages of pole separation during the first cell cycle. The initial separation occurs during pronuclear centration, the second during the streak stage, and the final one during the late stages of mitosis. At telophase, polar microtubules appear to extend into the cortex supporting the cell surface at all regions except the presumptive cleavage site.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970030303
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