Microtubule arrays in the cortex and near the germinal vesicle of immature starfish oocytes

Otto, Joann J.; Schroeder, Thomas E.

doi:10.1016/0012-1606(84)90141-6

Cited by 54 publications

(23 citation statements)

References 29 publications

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“…Before 1 -MeAde stimulation, an area with long rays of microtubules, which corresponds to the reported "pre-meiotic aster" or "aster-like structure" (16,20,21), was observed at the animal pole side of GV. Since two distinct asters which later develop into the MA always appear at the center of this area, this area seems to be the precursor of asters.…”

Section: Morphologymentioning

confidence: 60%

“…In both the whole and extracted oocytes remarkable changes were not observed at least up to the first polar body formation. The possible interconversion between the meshwork of microtubules present in the oocyte cortex and the MA for meiotic divisions has been reported (16,21). Although not statistically significant, the tubulin moiety in the residual structures tended to decrease around the second polar body formation and to increase up to the pronucleus stage.…”

Section: Estimation Of the Amount Of Tubulinmentioning

confidence: 93%

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Dynamics of Mitotic Apparatus Formation and Tubulin Content during Oocyte Maturation in Starfish

Shirai¹,

Hosoya²,

Sawada³

et al. 1990

Dev Growth Differ

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To follow the topo-temporal behavior of structures containing tubulin and the change in tubulin content during oocyte maturation, starfish oocytes were extracted with a medium containing detergent so that morphological observation and biochemical analysis could be conducted on the same residual oocyte preparation simultaneously. Before 1 -methyladenine (1 -MeAde) stimulation, "pre-meiotic asters" were observed on the germinal vesicle at the animal pole. 1-MeAde caused the appearance of distinct asters at the position of the aster precursor. When germinal vesicle breakdown (GVBD) took place, chromosomes were condensed. Chromosome gathering was concurrent with a reduction in the size of nuclear matrix. The mitotic apparatus was first constructed parallel to the cortex and then changed its axis perpendicularly. Fluorescence of tubulin due to indirect immunofluorescence in the cytoplasm other than the mitotic apparatus decreased rapidly along the course of maturation at least up to the first metaphase. Despite these dynamic morphological change, the tubulin content in the whole oocyte and the residual structures, measured by SDS-PAGE and immunostaining, did not show remarkable (statistically significant) changes through the course of maturation, although the content tended to decrease a little before the second polar body formation and to increase thereafter in the latter.

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Section: Morphologymentioning

confidence: 60%

Section: Estimation Of the Amount Of Tubulinmentioning

confidence: 93%

Dynamics of Mitotic Apparatus Formation and Tubulin Content during Oocyte Maturation in Starfish

Shirai¹,

Hosoya²,

Sawada³

et al. 1990

Dev Growth Differ

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“…In addition, there was a spatial pattern to the disappearance. The GV is located within 5-10 m of the cell surface at the animal pole (the site of polar body extrusion), and the centrosomes are present in this small space between the GV and cell surface (Otto and Schroeder, 1984). When the oocyte was imaged in an orientation so that the animalvegetal axis was in the plane of focus, it was possible to see the timing of the disappearance of these spots relative to the oocyte polarity.…”

Section: Cyclin B Gfp Localizes To Aggregatesmentioning

confidence: 99%

“…The oocyte was oriented so that the animal vegetal axis was in the plane of focus of the microscope. The GV is positioned close to the cell surface at the animal pole, and the centrosomes are present in the small region between the GV and the cell surface (Otto and Schroeder, 1984). Cyclin B-GFP enters from the side of the nucleus closest to the centrosomes.…”

Section: Accumulation In the Nucleusmentioning

confidence: 99%

Localization and Dynamics of Cdc2-Cyclin B during Meiotic Reinitiation in Starfish Oocytes

Terasaki

Okumura

Hinkle

et al. 2003

MBoC

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The Cdc2-cyclin B kinase has a central role in regulating the onset of M phase. In starfish oocytes, Cdc2-cyclin B begins to be activated ϳ10 min after application of maturation hormone, followed by accumulation in the nucleus then nuclear envelope breakdown. By immunofluorescence and by expressing a green fluorescent (GFP) chimera of cyclin B, we find that cyclin B is present in aggregates in the cytoplasm of immature oocytes. The aggregates disperse at ϳ10 min, suggesting that the dispersal is closely related to the activation of the kinase. Using cyclin B-GFP, the dispersion begins from the region containing the centrosomes. Extractability of Cdc2-cyclin B changes with similar kinetics during maturation. Active Cdc25 phosphatase released Cdc2-cyclin B from the detergent-insoluble fraction independently of its phosphatase activity. Live cell imaging also showed that Cdc2-cyclin B begins to accumulate in the nucleus before changes in nuclear pore permeability, consistent with Cdc2-cyclin B-induced disassembly of the pores. INTRODUCTIONThe Cdc2/cdk1 kinase triggers the onset of M phase (Nurse, 1990). Activation of Cdc2 requires association with cyclin B and dephosphorylation of Thr 14 and Tyr 15 on Cdc2; the phosphorylation state is governed by the relative activities of Wee1 family kinases and Cdc25 phosphatase (reviewed in Lew and Kornbluth, 1996). Inactive Cdc2-cyclin B is present in the cytoplasm during interphase and after it is activated, accumulates in the nucleus where it phosphorylates multiple targets to cause nuclear envelope breakdown (Pines and Hunter, 1991;Ookata et al., 1992).There are still many aspects of this system that are not well understood. The pathway leading to activation is different in different organisms and has not been established except in starfish (Okumura et al., 2002). Phosphorylation of cyclin is probably involved in the regulation of nuclear entry (Li et al., 1997;Hagting et al., 1998;Toyoshima et al., 1998;Yang et al., 1998) but may have other roles as well (Peter et al., 2002).Another subject of uncertainty regards Cdc2-cyclin B localization in the cytoplasm and its possible associations with other molecules in the cytoplasm. There are several indications that inactive Cdc2-cyclin B is not free to diffuse in the cytosol but instead, is associated with other molecules or intracellular structures and undergoes changes in associations when it becomes activated. Among various reports, Picard and Peaucellier (1998) observed cyclin B in vesiclelike structures in starfish oocytes, Westendorf et al. (1989) found evidence for cyclin B aggregates in immature clam oocytes, and Lee and Kirschner (1996) found evidence for a binding inhibitor of Cdc2-cyclin B that is associated with membranes. More recently, inactive Cdc2-cyclin B was found to be associated with annulate lamellae in immature Xenopus oocytes (Beckhelling et al., 2003).Current techniques for localization are subject to limitations of various kinds. The use of green fluorescent protein (GFP) chimeras is promising because loc...

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“…Immature oocytes, arrested in early prophase of meiosis I, contain two asters (premeiotic asters) located between the eccentric germinal vesicle (GV) and the animal pole (Otto and Schroeder, 1984;Picard et al, 1988;Miyazaki et al, 2000). The basis of our new experimental procedure is that the centrosomes are in the loci of the respective premeiotic asters (Uetake et al, 2002).…”

Section: Experimental Protocolmentioning

confidence: 99%

Centrosome destined to decay in starfish oocytes

Shirato

Tamura

Yoneda³

et al. 2006

Development

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In contrast to the somatic cell cycle, duplication of the centrioles does not occur in the second meiotic cycle. Previous studies have revealed that in starfish each of the two centrosomes in fully-grown immature oocytes consists of two centrioles with different destinies: one survives and retains its reproductive capacity, and the other is lost after completion of meiosis. In this study, we investigated whether this heterogeneity of the meiotic centrioles is already determined before the re-initiation of meiosis. We prepared a small fragment of immature oocyte containing the four centrioles and fused it electrically with a mature egg in order to transfer two sets of the premeiotic centrioles into the mature cytoplasm. Two asters were present in this conjugate, and in each of them only a single centriole was detected by electron microscopy. In the first mitosis of the conjugate artificially activated without sperm, two division poles formed, each of which doubled in each subsequent round of mitosis. These results indicate that only two of the four premeiotic centrioles survived in the mature cytoplasm and that they retained their reproductive capacity, which suggests that the heterogeneity of the maternal centrioles is determined well before re-initiation of meiosis,and that some factor in the mature cytoplasm is responsible for suppressing the reproductive capacity of the centrioles destined to decay.

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Microtubule arrays in the cortex and near the germinal vesicle of immature starfish oocytes

Cited by 54 publications

References 29 publications

Dynamics of Mitotic Apparatus Formation and Tubulin Content during Oocyte Maturation in Starfish

Dynamics of Mitotic Apparatus Formation and Tubulin Content during Oocyte Maturation in Starfish

Localization and Dynamics of Cdc2-Cyclin B during Meiotic Reinitiation in Starfish Oocytes

Centrosome destined to decay in starfish oocytes

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