Cdc42 Activation Couples Spindle Positioning to First Polar Body Formation in Oocyte Maturation

Abstract Oocyte maturation is a prerequisite for successful fertilization and embryo development. Incomplete oocyte maturation can result in infertility. Ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) has been found to be implicated in oocyte maturation and embryo development. However, the cellular and molecular mechanisms of UCH-L1 underlying oocyte maturation have not been fully elucidated. In the present study, we observed that the introduction of UCH-L1 inhibitor LDN-57444 suppressed first polar body extrusion during mouse oocyte maturation. The inhibition of UCH-L1 by LDN-57444 led to the notable increase in reactive oxygen species (ROS) level, conspicuous reduction in glutathione (GSH) content and mitochondrial membrane potential (MMP), and blockade of spindle body formation. As a conclusion, UCH-L1 inhibitor LDN-57444 suppressed mouse oocyte maturation by improving oxidative stress, attenuating mitochondrial function, curbing spindle body formation and down-regulating extracellular signal-related kinases (ERK1/2) expression, providing a deep insight into the cellular and molecular basis of UCH-L1 during mouse oocyte maturation.

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Meiotic Spindle Formation Following Inhibition of First Polar Body Formation in the Zhikong Scallop (Chlamys farreri Jones et Preston)

Frontiers in Marine Science ◽

10.3389/fmars.2021.653000 ◽

2021 ◽

Vol 8 ◽

Author(s):

Yongren Li ◽

Baolu Zhang ◽

Shuang Liang ◽

Yongjun Guo

Keyword(s):

Chromosome Segregation ◽

Polar Body ◽

Metaphase Plate ◽

Fluorescein Isothiocyanate ◽

Chlamys Farreri ◽

Meiotic Spindle ◽

Zhikong Scallop ◽

Body Formation ◽

First Polar Body ◽

Polar Body Formation

Fertilized Zhikong scallop (Chlamys farreri) eggs were treated with cytochalasin B (CB 0.5 mg/L) at 14–15 min postfertilization to inhibit first polar body formation. The eggs were then stained with fluorescein isothiocyanate (FITC) -anti-α-tubulin and propidium iodide (PI) to examine their microtubule patterns and chromosome, respectively. Fluorescent microscope observations of treated eggs sampled every 2–3 min during meiotic maturation revealed meiotic apparatus assembly and correlated chromosome segregation. In CB-treated groups, meiosis I proceeded normally and produced two groups of dyads, with 19 in each group. Both dyad groups were retained in the eggs as they entered meiosis II. Two, three, or four asters (centrosome with microtubules around it) in meiosis II rearranged the spindle in several patterns: bipolar [24.0 ± 4.1 μm (long axis) × 18.3 ± 4.1 μm (diameter: metaphase plate)], tripolar (18.6 ± 3.9 μm × 9.9 ± 1.3 μm), separated bipolar (18.3 ± 2.8 μm × 11.2 ± 1.8 μm), and other unclassified spindle patterns. Corresponding chromosome segregation, including bipolar (18.9%), tripolar (38.9%), double bipolar (16.5%), and unclassified (25.6%), was observed during meiosis II in CB-treated eggs. The data indicated that chromosome segregation patterns determined by spindle patterns were critically influenced by the number of centrosomes in meiosis II eggs following inhibition of polar body 1 (PB1) formation with CB.

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The Process of First Polar Body Formation in Eggs of the Androgenetic ClamCorbicula fluminea

Journal of Shellfish Research ◽

10.2983/035.037.0111 ◽

2018 ◽

Vol 37 (1) ◽

pp. 131-137 ◽

Cited By ~ 1

Author(s):

Masaru Hotta ◽

Akira Komaru

Keyword(s):

Polar Body ◽

Body Formation ◽

First Polar Body ◽

Polar Body Formation

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Changes in Organization of the Endoplasmic Reticulum duringXenopus Oocyte Maturation and Activation

Molecular Biology of the Cell ◽

10.1091/mbc.12.4.1103 ◽

2001 ◽

Vol 12 (4) ◽

pp. 1103-1116 ◽

Cited By ~ 88

Author(s):

Mark Terasaki ◽

Linda L. Runft ◽

Arthur R. Hand

Keyword(s):

Endoplasmic Reticulum ◽

Fluorescent Protein ◽

Polar Body ◽

Meiotic Spindle ◽

Body Formation ◽

Nuclear Envelope Breakdown ◽

First Polar Body ◽

Polar Body Formation ◽

Green Fluorescent ◽

Small Clusters

The organization of the endoplasmic reticulum (ER) in the cortex ofXenopus oocytes was investigated during maturation and activation using a green fluorescent protein chimera, immunofluorescence, and electron microscopy. Dense clusters of ER developed on the vegetal side (the side opposite the meiotic spindle) during maturation. Small clusters appeared transiently at the time of nuclear envelope breakdown, disappeared at the time of first polar body formation, and then reappeared as larger clusters in mature eggs. The appearance of the large ER clusters was correlated with an increase in releaseability of Ca2+ by IP3. The clusters dispersed during the Ca2+ wave at activation. Possible relationships of ER structure and Ca2+ regulation are discussed.

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H1foo is essential for in vitro meiotic maturation of bovine oocytes

Zygote ◽

10.1017/s0967199414000021 ◽

2014 ◽

Vol 23 (3) ◽

pp. 416-425 ◽

Cited By ~ 13

Author(s):

Yan Yun ◽

Peng An ◽

Jing Ning ◽

Gui-Ming Zhao ◽

Wen-Lin Yang ◽

...

Keyword(s):

Oocyte Maturation ◽

Polar Body ◽

Linker Histone ◽

Meiotic Maturation ◽

Control Group ◽

Bovine Oocyte ◽

First Polar Body ◽

Effective Sirnas ◽

Bovine Oocytes

SummaryOocyte-specific linker histone, H1foo, is localized on the oocyte chromosomes during the process of meiotic maturation, and is essential for mouse oocyte maturation. Bovine H1foo has been identified, and its expression profile throughout oocyte maturation and early embryo development has been established. However, it has not been confirmed if H1foo is indispensable during bovine oocyte maturation. Effective siRNAs against H1foo were screened in HeLa cells, and then siRNA was microinjected into bovine oocytes to down-regulate H1foo expression. H1foo overexpression was achieved via mRNA injection. Reverse transcription polymerase chain reaction (RT-PCR) results indicated that H1foo was up-regulated by 200% and down-regulated by 70%. Based on the first polar body extrusion (PB1E) rate, H1foo overexpression apparently promoted meiotic progression. The knockdown of H1foo significantly impaired bovine oocyte maturation compared with H1foo overexpression and control groups (H1foo overexpression = 88.7%, H1foo siRNA = 41.2%, control = 71.2%; P < 0.05). This decrease can be rescued by co-injection of a modified H1foo mRNA that has escaped from the siRNA target. However, the H1e (somatic linker histone) overexpression had no effect on PB1E rate when compared with the control group. Therefore we concluded that H1foo is essential for bovine oocyte maturation and its overexpression stimulates the process.

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Polar Body Formation in Tubifex Eggs

Annals of the New York Academy of Sciences ◽

10.1111/j.1749-6632.1990.tb21685.x ◽

1990 ◽

Vol 582 (1 Cytokinesis) ◽

pp. 260-272 ◽

Cited By ~ 18

Author(s):

TAKASHI SHIMIZU

Keyword(s):

Polar Body ◽

Body Formation ◽

Polar Body Formation

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Memoirs: The Germ-Cell Cycle in Phytophaga destructor Say

Journal of Cell Science ◽

10.1242/jcs.s2-77.308.585 ◽

1935 ◽

Vol s2-77 (308) ◽

pp. 585-604

Author(s):

MARGOT E. METEALFE

Keyword(s):

Germ Cells ◽

Growth Stage ◽

Germ Line ◽

Polar Body ◽

Metaphase Plate ◽

Body Formation ◽

Polar Bodies ◽

Complicated Process ◽

Female Pronucleus ◽

Polar Body Formation

1. The somatic cells in both sexes of Phytophaga destructor Say contain four pairs of V-shaped chromosomes, the sex-group being indistinguishable in size or form. 2. The germ-cells in both sexes contain eight pairs of chromosomes. 3. The maturation of the egg follows the normal course of development, eight bivalents being formed. After polar body formation the female pronucleus has eight chromosomes. The polar bodies are never extruded from the egg. 4. Spermatogenesis is a complicated process, the details of which have not been satisfactorily determined. The growth stage appears to take place before the last spermatogonial division. No pairing of chromosome has been observed, and apparently no metaphase plate is formed at meiosis. Eeduction is effected by the expulsion of two buds each containing four chromosomes. Thus only one sperm is produced from each spermatocyte. 5. One or more sperms may enter the egg at fertilization. 6. The germ-line is differentiated from the soma at the eightcell stage. 7. At the fifth cleavage the somatic nuclei eliminate half their number of chromosomes, and are left with eight chromosomes. 8. Migration of the germ nuclei takes place at the sixteencell stage. 9. The relation of the chromosome numbers in the somatic and germ lines is discussed.

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Preimplantation development of gynogenetic diploid mouse embryos

Development ◽

10.1242/dev.69.1.215 ◽

1982 ◽

Vol 69 (1) ◽

pp. 215-222

Author(s):

Ewa Borsuk

Keyword(s):

Cytochalasin B ◽

Polar Body ◽

Mouse Embryos ◽

Fertilization In Vitro ◽

Body Formation ◽

Male Pronucleus ◽

Step Procedure ◽

Gynogenetic Diploid ◽

Polar Body Formation

Diploid gynogenetic mouse embryos were produced in a three-step procedure: fertilization in vitro, suppression of the 2nd polar body formation by Cytochalasin B, and microsurgical removal of the male pronucleus. The operated eggs were transplanted to the oviduct of recipient females for 72 or 96 h. The overall recovery rate was 73%, but compacted morulae and blastocysts constituted only 28·6% of transplanted eggs. After 72 h blastocysts were rare (3·5%) but 24 h later their incidence increased to 21·2%. In eggs homozygous for T6 chromosome it was possible to prove karyologically that the male pronucleus was effectively removed and that the diploid genome was of purely maternal origin.

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