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Reorganization of actin filaments by ADF/cofilin is involved in formation of microtubule structures during Xenopus oocyte maturation.

Yamagishi Y, Abe H - Mol. Biol. Cell (2015)

Bottom Line: Suppression of XAC dephosphorylation by anti-XSSH antibody injection inhibited both actin filament reorganization and proper formation and localization of both the MTOC-TMA and meiotic spindles.Nocodazole also caused the MTOC-TMA and the cytoplasmic actin filaments at its base region to disappear, which further impeded disassembly of intranuclear actin filaments from the vegetal side.XAC appears to reorganize cytoplasmic actin filaments required for precise assembly of the MTOC and, together with the MTOC-TMA, regulate the intranuclear actin filament disassembly essential for meiotic spindle formation.

View Article: PubMed Central - PubMed

Affiliation: Department of Nanobiology, Graduate School of Advanced Integration Science, Chiba University, Chiba 263-8522, Japan.

No MeSH data available.


Related in: MedlinePlus

Structure of the intranuclear actin filaments. Eleven oocytes derived from four different females were examined. The nucleus of a midsagittal (animal–vegetal) cryosection of a full-grown stage VI oocyte was stained with Alexa 488–phalloidin (A) and double stained with Alexa 488–phalloidin and anti-lamin antibody (B). Arrows indicate the actin filaments surrounding the nucleus. (C) Enlarged image of the nucleus by assembling three shots, which had to be taken to cover one section, in a composite plate. The vegetal region (D) and animal region (E) are further enlarged. (F) Comparison of the actin filament mesh size between the vegetal (Veg) and animal (An) sides. The area of the space surrounded by actin filaments (the mesh hole) was measured over a set range by ImageJ software. Twelve oocytes from nine different females were measured. Relative mesh size at the animal side. Bars, 100 μm (A, B), 50 μm (C–E). An, animal pole; Vg, vegetal pole.
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Figure 1: Structure of the intranuclear actin filaments. Eleven oocytes derived from four different females were examined. The nucleus of a midsagittal (animal–vegetal) cryosection of a full-grown stage VI oocyte was stained with Alexa 488–phalloidin (A) and double stained with Alexa 488–phalloidin and anti-lamin antibody (B). Arrows indicate the actin filaments surrounding the nucleus. (C) Enlarged image of the nucleus by assembling three shots, which had to be taken to cover one section, in a composite plate. The vegetal region (D) and animal region (E) are further enlarged. (F) Comparison of the actin filament mesh size between the vegetal (Veg) and animal (An) sides. The area of the space surrounded by actin filaments (the mesh hole) was measured over a set range by ImageJ software. Twelve oocytes from nine different females were measured. Relative mesh size at the animal side. Bars, 100 μm (A, B), 50 μm (C–E). An, animal pole; Vg, vegetal pole.

Mentions: We first observed the morphology of intranuclear actin filaments during oocyte maturation. Because oocytes indeed possess a high background of fluorescence by immunofluorescence microscopy, we confirmed that control staining by each secondary antibody alone did not stain any structures that were stained specifically by the primary antibody or tetramethylrhodamine (TMR)-phalloidin (Supplemental Figure S1). The mesh of intranuclear actin filaments was clearly stained with Alexa 488–phalloidin in vertical sections of immature stage VI oocytes (Figure 1, A–C). Actin filaments were also located in the cytoplasm surrounding the nuclei (Figure 1A, arrows), as expected (Loeder and Gard, 1994). We confirmed that these filaments are present outside the nuclei by dual staining with anti-lamin antibody and Alexa 488–phalloidin (Figure 1B). Magnification of intranuclear actin filament networks in vertical sections (Figure 1C) revealed the transition of the network structures along the animal-to-vegetal axis. The actin networks were dense and sponge-like at the vegetal side of the nuclei (Figure 1D), as previously reported (Bohnsack et al., 2006), and rather loose and straight toward the animal pole (Figure 1E). We confirmed these structural differences by quantifying the mesh size (Figure 1F). Furthermore, the amount of intranuclear actin filaments fluctuated during oocyte maturation until GVBD (Supplemental Figure S2A); the intensity of actin filament staining increased at the relative time point of 0.2 (about one-fifth of the way between progesterone treatment and GVBD) and returned to its original level at relative time points 0.4 and 0.6 (Supplemental Figure S2A).


Reorganization of actin filaments by ADF/cofilin is involved in formation of microtubule structures during Xenopus oocyte maturation.

Yamagishi Y, Abe H - Mol. Biol. Cell (2015)

Structure of the intranuclear actin filaments. Eleven oocytes derived from four different females were examined. The nucleus of a midsagittal (animal–vegetal) cryosection of a full-grown stage VI oocyte was stained with Alexa 488–phalloidin (A) and double stained with Alexa 488–phalloidin and anti-lamin antibody (B). Arrows indicate the actin filaments surrounding the nucleus. (C) Enlarged image of the nucleus by assembling three shots, which had to be taken to cover one section, in a composite plate. The vegetal region (D) and animal region (E) are further enlarged. (F) Comparison of the actin filament mesh size between the vegetal (Veg) and animal (An) sides. The area of the space surrounded by actin filaments (the mesh hole) was measured over a set range by ImageJ software. Twelve oocytes from nine different females were measured. Relative mesh size at the animal side. Bars, 100 μm (A, B), 50 μm (C–E). An, animal pole; Vg, vegetal pole.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Figure 1: Structure of the intranuclear actin filaments. Eleven oocytes derived from four different females were examined. The nucleus of a midsagittal (animal–vegetal) cryosection of a full-grown stage VI oocyte was stained with Alexa 488–phalloidin (A) and double stained with Alexa 488–phalloidin and anti-lamin antibody (B). Arrows indicate the actin filaments surrounding the nucleus. (C) Enlarged image of the nucleus by assembling three shots, which had to be taken to cover one section, in a composite plate. The vegetal region (D) and animal region (E) are further enlarged. (F) Comparison of the actin filament mesh size between the vegetal (Veg) and animal (An) sides. The area of the space surrounded by actin filaments (the mesh hole) was measured over a set range by ImageJ software. Twelve oocytes from nine different females were measured. Relative mesh size at the animal side. Bars, 100 μm (A, B), 50 μm (C–E). An, animal pole; Vg, vegetal pole.
Mentions: We first observed the morphology of intranuclear actin filaments during oocyte maturation. Because oocytes indeed possess a high background of fluorescence by immunofluorescence microscopy, we confirmed that control staining by each secondary antibody alone did not stain any structures that were stained specifically by the primary antibody or tetramethylrhodamine (TMR)-phalloidin (Supplemental Figure S1). The mesh of intranuclear actin filaments was clearly stained with Alexa 488–phalloidin in vertical sections of immature stage VI oocytes (Figure 1, A–C). Actin filaments were also located in the cytoplasm surrounding the nuclei (Figure 1A, arrows), as expected (Loeder and Gard, 1994). We confirmed that these filaments are present outside the nuclei by dual staining with anti-lamin antibody and Alexa 488–phalloidin (Figure 1B). Magnification of intranuclear actin filament networks in vertical sections (Figure 1C) revealed the transition of the network structures along the animal-to-vegetal axis. The actin networks were dense and sponge-like at the vegetal side of the nuclei (Figure 1D), as previously reported (Bohnsack et al., 2006), and rather loose and straight toward the animal pole (Figure 1E). We confirmed these structural differences by quantifying the mesh size (Figure 1F). Furthermore, the amount of intranuclear actin filaments fluctuated during oocyte maturation until GVBD (Supplemental Figure S2A); the intensity of actin filament staining increased at the relative time point of 0.2 (about one-fifth of the way between progesterone treatment and GVBD) and returned to its original level at relative time points 0.4 and 0.6 (Supplemental Figure S2A).

Bottom Line: Suppression of XAC dephosphorylation by anti-XSSH antibody injection inhibited both actin filament reorganization and proper formation and localization of both the MTOC-TMA and meiotic spindles.Nocodazole also caused the MTOC-TMA and the cytoplasmic actin filaments at its base region to disappear, which further impeded disassembly of intranuclear actin filaments from the vegetal side.XAC appears to reorganize cytoplasmic actin filaments required for precise assembly of the MTOC and, together with the MTOC-TMA, regulate the intranuclear actin filament disassembly essential for meiotic spindle formation.

View Article: PubMed Central - PubMed

Affiliation: Department of Nanobiology, Graduate School of Advanced Integration Science, Chiba University, Chiba 263-8522, Japan.

No MeSH data available.


Related in: MedlinePlus