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  • 1
    ISSN: 0886-1544
    Keywords: actin ; cleavage ; fluorescein-labeled phalloidin ; microinjection ; phalloidin ; sand dollar eggs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Effects of microinjection of phalloidin on fertilization and cleavage of sand dollar (Clypeaster japonicus and Scaphechinus mirabilis) eggs were studied. The drug, previously injected into unfertilized eggs, showed no effect on the elevation of the fertilization membrane upon insemination up to an intracellular concentration of 50 μM. However, the movement of the egg pronucleus to the sperm pronucleus was inhibited and the fusion of pronuclei did not occur. The subsequent development no longer took place. When phalloidin was injected into fertilized eggs, the thickness of the cortical layer increased and the microvilli became conspicuous. Both nuclear division and cleavage were inhibited at the intracellular concentration of more than 20 μM, though the latter seemed to be more sensitive to phalloidin than the former.Fluorescein-labeled phalloidin (FL-phalloidin) was injected into eggs in order to investigate F-actin localization by fluorescence microscopy. In both unfertilized and fertilized eggs, FL-phalloidin was localized in the cortical layer within 1 min after injection. It was also localized in the cortical layer as radially oriented rodlike structures when injected into fertilized eggs before the disappearance of the nuclear membrane. No distinct fluorescence was detected in the mitotic apparatus or in the cleavage furrow. FL-phalloidin redistributed gradually into egg cytoplasm. In unfertilized eggs, fluorescent rods were found especially in the egg pronucleus 30 min after injection.
    Additional Material: 6 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 46-53 
    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.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 549-559 
    ISSN: 0886-1544
    Keywords: activation ; microinjection ; polar body ; sea urchin eggs ; starfish oocytes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Redistribution of alpha-actinin during fertilization was investigated by means of the microinjection of fluorescently labeled egg alpha-actinin in the sea urchin, Hemicentrotus pulcherrimus. Upon fertilization, labeled alpha-actinin accumulated locally around the sperm binding site, where the fertilization cone formed soon afterwards. The accumulation propagated all over the cortex within 10 sec after a latent period of 10-20 sec. When an egg in Na-free seawater was injected with both alpha-actinin and calcium buffer (intracellular free Ca2+ concentration = 9 μM), the accumulation of alpha-actinin was similar to that in normal seawater, which suggests that the accumulation did not depend on the increase in intracellular pH but only on the increase in the intracellular free Ca2+ concentration. In immature oocytes the accumulation was detected in the cortical region, including the huge protruding cytoplasm where the sperm entered. When labeled egg alpha-actinin was injected into starfish (Asterias amurensis) oocytes followed by insemination, it accumulated in the cortical layer in a manner similar to the case of sea urchin, except that the accumulation in fertilization cones of maturing oocytcs or reception cones of immature oocytes appeared ringlike and rodlike, respectively. Moreover, just after the arrival of the meiotic apparatus, egg alpha-actinin accumulated in the cortical region, where the formation of the polar body was expected. This suggests that the meiotic apparatus somehow induced the differentiation of the cortex so as to form a polar body. It is concluded that the cortical region where alpha-actinin accumulated coincided with the microfilament-rich region. This suggests that alpha-actinin plays a role in forming the cortical meshwork of actin filaments.
    Additional Material: 8 Ill.
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  • 4
    ISSN: 0886-1544
    Keywords: dynein ; mitosis ; chromosome movement ; immnunofluorescence observation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A monoclonal antibody against sea urchin (Hemicentrotus pulcherrimus) sperm flagellar 21S dynein was characterized and sued to identify and localized cytoplasmic dynein of sea urchin eggs by the methods of immunoblotting and indirect immunofluorescence microscopy. D57, the monoclonal antibody used in this study, was directed to the Aβ polypeptide of 21S dynein. D57 stained sperm flagella specifically but did not inhibit Mg-ATPase activity of 21S dynein, its recombination ability with NaCl-extracted axonemes, or the movement of demembranated sperm. D57 cross-reacted with sea urchin egg cytoplasmic dynein. High molecular weight cytoplasmic dynein polypeptide which had the same electrophoretic mobility s flagellar dynein. A chains was the only polypeptide that reacted with D57 in the crude extract from unfertilized sea urchin eggs. Indirect immunofluorescence observations showed that the mitotic apparatus was stained most intensely in the frozen sections and lysed eggs. In the mitotic apparatus isolated at metaphase, the half spindles were stained more strongly than the astral regions. The regions near chromosomes in the half spindle appeared to be stained particularly. Staining of the interzone was also observed in the mitotic spindle isolated at anaphase. Comparison of the staining patterns for cytoplasmic dynein with that for tubulin suggested that cytoplasmic dynein was localized where microtubules were densely organized, but its distribution may not necessarily be identical with that of microtubules.
    Additional Material: 7 Ill.
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  • 5
    ISSN: 0886-1544
    Keywords: fertilization cone ; fluorescence redistribution after photobleaching ; fluorescent analog cytochemistry ; microinjection of actin ; microvilli ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Actin from sea urchin eggs was fluorescently labeled with fluorescein isothiocyanate (FITC), N-(7-dimethylamino-4-methylcoumarinyl)-maleimide (DACM), or 5-iodoacetamidofluorescein (IAF) and microinjected into sea urchin eggs and oocytes. It distributed evenly in the cytoplasm of unfertilized eggs. Upon fertilization, actin accumulated first around the sperm binding site and, soon afterwards, in the fertilization cone. The accumulation propagated all over the cortex after a latent period of 10-20 sec. In the case of Clypeaster japonicus eggs, propagation of the accumulation coincided with a shape change in the egg, suggesting that the accumulated actin in the cortex generates forces. FITC-actin was incorporated into microvilli and retained in the cortex after cleavage. On the other hand, DACM- or IAF-actin was not incorporated into microvilli and was dispersed from the cortex by cleavage. These differences may be attributable to differences in the properties of the actins labeled at different sites. After photobleaching by laser light irradiation, FITC- or IAF-actin redistributed in the cortex of fertilized egg as quickly as it did before fertilization. When an unfertilized egg was injected with both actin and a calcium buffer (intracellular free Ca2+ concentration 9 μM), the actin accumulation was similar to that during fertilization but without the latent period. This suggests that the accumulation depended on the increase in the intracellular free Ca2+ concentration. When the unfertilized egg was injected with 0.2 M EGTA after injection of labeled actin and then inseminated, it accumulated only in the protrusion of cytoplasm where the sperm had entered, and fertilization was not completed. In immature oocytes, the accumulation was observed in the cortical region, including the huge protrusion of the cytoplasm where the sperm had entered. These results suggest that actin accumulation in the sperm binding site plays an important role in the sperm reception mechanism of the egg.
    Additional Material: 7 Ill.
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  • 6
    Publication Date: 2016-10-07
    Description: Author Posting. © Marine Biological Laboratory, 2009. This article is posted here by permission of Marine Biological Laboratory for personal use, not for redistribution. The definitive version was published in Biological Bulletin 216 (2009): 40-44.
    Description: Calyculin-A (CLA), a protein phosphatase inhibitor, has been known to induce cleavage resembling normal furrowing in unfertilized sea urchin eggs. In CLA-treated eggs, actin filaments and myosin assemble to form a contractile ring-like structure in the egg cortex; however, this occurs in the absence of a mitotic spindle or asters. Here, we investigated the relationship between the plane of CLA-induced cleavage and the intrinsic animal-vegetal polar axis in sea urchin eggs. The animal-vegetal axis was established using black ink to visualize the jelly canal located at the animal pole in the jelly coat surrounding the egg. We measured the acute angle between the jelly canal axis and the cleavage plane for both fertilized eggs and CLA-treated unfertilized eggs. Although the acute angle lay within 10 degrees for most of the fertilized eggs, it varied widely for CLA-treated unfertilized eggs. Measurements of the diameter of blastomeres revealed that cleavage of fertilized eggs took place in the mid-plane of the egg, but that CLA-induced divisions were unequal. These results suggest that neither the orientation nor the location of the CLA-induced cleavage furrow is related to the animal-vegetal polar axis of the egg, even though the furrowing mechanism itself is not dissimilar to that in fertilized eggs.
    Description: This study was supported by research grants from the JSPS (#15207013) to I. M., and facilities provided to S. I. by the Marine Biological Laboratory, Woods Hole, Massachusetts.
    Keywords: CLA ; Calyculin-A ; CR, contractile ring
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 419 (2002), S. 27-28 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The ability of cells to multiply lies at the heart of many biological processes. In multicellular organisms such as ourselves, cell proliferation is essential for growth and development, and to replace cells spent by daily wear and tear. For single-celled species such as yeasts, proliferation is ...
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Biochemistry 28 (1989), S. 102-106 
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
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  • 9
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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