Immunocytochemical localization of actin in the nucleolus of rat oocytes

Funaki, Kenji; Katsumoto, Tetsuo; Iino, Akihiro

doi:10.1016/0248-4900(96)89423-8

Cited by 23 publications

(8 citation statements)

References 28 publications

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“…The finding of the motor proteins, actin (Funaki et al 1995) and myosin I (Pestic-Dragovich et al 2000), in the nucleolus opened the possibility that they might aid in that process. Very recently, it was shown that both nuclear actin and myosin I are associated with the rDNA chromatin and with the RNA pol I transcription machinery (Philimonenko et al 2004).…”

Section: Dynamics Of Ribosome Assemblymentioning

confidence: 98%

The moving parts of the nucleolus

Olson

Dundr

2005

Histochem Cell Biol

187

175

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The cell nucleolus is the subnuclear body in which ribosomal subunits are assembled, and it is also the location of several processes not related to ribosome biogenesis. Recent studies have revealed that nucleolar components move about in a variety of ways. One class of movement is associated with ribosome assembly, which is a vectorial process originating at the sites of transcription in the border region between the fibrillar center and the dense fibrillar component. The nascent preribosomal particles move outwardly to become the granular components where further maturation takes place. These particles continue their travel through the nucleoplasm for eventual export to the cytoplasm to become functional ribosomes. In a second kind of motion, many nucleolar components rapidly exchange with the nucleoplasm. Thirdly, nucleolar components engage in very complex movements when the nucleolus disassembles at the beginning of mitosis and then reassembles at the end of mitosis. Finally, many other cellular and viral macromolecules, which are not related to ribosome assembly, also pass through or are retained by the nucleolus. These are involved in nontraditional roles of the nucleolus, including regulation of tumor suppressor and oncogene activities, signal recognition particle assembly, modification of small RNAs, control of aging, and modulating telomerase function.

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Section: Dynamics Of Ribosome Assemblymentioning

confidence: 98%

The moving parts of the nucleolus

Olson

Dundr

2005

Histochem Cell Biol

187

175

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“…However, dinoflagellate chromosomes never decondense, so this function can be ruled out. Recently, it was suggested [26] that actin could be involved in the formation of the compacted structure of 10). The phalloidin fluorescence is well detectable in the nucleus Neen the chromosomes and in the nucleolus (nu).…”

Section: Actin In Centrosome Region In Gl Phase and In Centrosome Regmentioning

confidence: 99%

Nuclear and cytoplasmic actin in dinoflagellates

Soyer‐Gobillard

Ausseil

Géraud

1996

Biology of the Cell

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Experiments using monoclonal and polyclonal anti-actin antibodies allowed us to demonstrate the presence of F- or G-actin in original protists, dinoflagellates, either by biochemistry, immunofluorescence and in TEM. SDS-PAGE electrophoresis and immunoblottings made either from total or nuclear protein extracts revealed the presence of a 44-kDa band reacting with monoclonal anti-actin antibody in two species, Prorocentrum micans and Crypthecodinium cohnii, and thus demonstrated the presence of actin in nuclear and cytoplasmic fractions. After squash preparation of P micans cells, actin was identified within the nucleus and in some regions of the cytoplasm by immunofluorescence microscopy. Labelling of both the nucleolus and the centrosome region was evident together with amorphous nucleoplasmic material surrounding the chromosomes. The use of cryosections of intact P micans and C cohnii cells for immunofluorescence along with staining with DAPI to delineate the chromosomes themselves, yielded finer resolution of the intranuclear network labelling pattern and allowed us to complete our observations, in particular on the cytoplasmic labelling. In P micans, in addition to the centrosome region, the cytoplasmic channels passing through the nucleus in dividing cells are labelled. In C cohnii, the cortex, the centrosome region, the cytoplasmic channels, the region surrounding the nucleus, the filaments linking it to the cortex and the cleavage furrow are also labelled. In the nucleus of the two species, there is a prominent "weft' of fine actin filaments in the nucleoplasm forming a matrix of varying density around the persistent chromosomes. This actin matrix, of unknown function, is most conspicuous at the end of the S-phase of the cell cycle. Fluorescent derivatives of phalloidin, used as diagnostic cytochemical probes for polymeric actin (F-actin), gave similar results. Positive TEM immunolabelling of intranuclear actin confirms its presence in the nucleoplasm, in the nucleolus where the preribosomal region is labelled while C cohnii chromosomes are unlabelled and the P micans chromosomes very slightly. In the cytoplasm, lips of the cleavage furrow and kinetosome regions are labelled as well as the centrosome region. The possible functions of this protein located in several compartments of dinoflagellate cells are discussed.

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“…Therefore, it appears that microfilaments are needed for microtubule functions, and the segregation of homologous chromosomes requires interaction between microtubules and microfilaments. In rat oocytes, significantly higher levels of associated actin were observed on metaphase I chromosomes (Funaki et al 1995). However, when mouse oocytes were treated with low-dose (1 mg/ml) cytochalasin D, anaphase I entry (chromosome segregation) occurred, although cytokinesis was blocked (Kubiak et al 1991, Verlhac et al 2000.…”

Section: Introductionmentioning

confidence: 99%

Regulation of dynamic events by microfilaments during oocyte maturation and fertilization

Sun¹,

Schatten²

2006

Reproduction

255

188

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Actin filaments (microfilaments) regulate various dynamic events during oocyte meiotic maturation and fertilization. In most species, microfilaments are not required for germinal vesicle breakdown and meiotic spindle formation, but they mediate peripheral nucleus (chromosome) migration, cortical spindle anchorage, homologous chromosome separation, cortex development/maintenance, polarity establishment, and first polar body emission during oocyte maturation. Peripheral cortical granule migration is controlled by microfilaments, while mitochondria movement is mediated by microtubules. During fertilization, microfilaments are involved in sperm incorporation, spindle rotation (mouse), cortical granule exocytosis, second polar body emission and cleavage ring formation, but are not required for pronuclear apposition (except for the mouse). Many of the events are driven by the dynamic interactions between myosin and actin filaments whose polymerization is regulated by RhoA, Cdc42, Arp2/3 and other signaling molecules. Studies have also shown that oocyte cortex organization and polarity formation mediated by actin filaments are regulated by mitogen-activated protein kinase, myosin light-chain kinase, protein kinase C and its substrate p-MARKS as well as PAR proteins. The completion of several dynamic events, including homologous chromosome separation, spindle anchorage, spindle rotation, vesicle organelle transport and pronuclear apposition (mouse), requires interactions between microfilaments and microtubules, but determination of how the two systems of the cytoskeleton precisely cross-link, and which proteins link microfilaments to microtubules to perform functions in eggs, requires further studies. Finally, the meaning of microfilament-mediated oocyte polarity versus embryo polarity and embryo development in different species (Drosophila, Xenopus and mouse) is discussed.

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Immunocytochemical localization of actin in the nucleolus of rat oocytes

Cited by 23 publications

References 28 publications

The moving parts of the nucleolus

The moving parts of the nucleolus

Nuclear and cytoplasmic actin in dinoflagellates

Regulation of dynamic events by microfilaments during oocyte maturation and fertilization

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