Melatonin Alleviates the Suppressive Effect of Hypoxanthine on Oocyte Nuclear Maturation and Restores Meiosis via the Melatonin Receptor 1 (MT1)-Mediated Pathway

It is well known that hypoxanthine (HX) inhibits nuclear maturation of oocytes by elevating the intracellular cAMP level, while melatonin (MT) is a molecule that reduces cAMP production, which may physiologically antagonize this inhibition and restore the meiosis process. We conducted in vitro and in vivo studies to examine this hypothesis. The results showed that 10–3 M MT potentiated the inhibitory effect of HX on mouse oocyte meiosis by lowering the rate of germinal vesicle breakdown (GVBD) and the first polar body (PB1). However, 10–5 M and 10–7 M MT significantly alleviated the nuclear suppression induced by HX and restored meiosis in 3- and 6-week-old mouse oocytes, respectively. We identified that the rate-limiting melatonin synthetic enzyme AANAT and melatonin membrane receptor MT1 were both expressed in oocytes and cumulus cells at the GV and MII stages. Luzindole, a non-selective melatonin membrane receptor antagonist, blocked the activity of MT on oocyte meiotic recovery (P < 0.05). This observation indicated that the activity of melatonin was mediated by the MT1 receptor. To understand the molecular mechanism further, MT1 knockout (KO) mice were constructed. In this MT1 KO animal model, the PB1 rate was significantly reduced with the excessive expression of cAPM synthases (Adcy2, Adcy6, Adcy7, and Adcy9) in the ovaries of these animals. The mRNA levels of Nppc and Npr2 were upregulated while the genes related to progesterone synthesis (Cyp11a11), cholesterol biosynthesis (Insig1), and feedback (Lhcgr, Prlr, and Atg7) were downregulated in the granulosa cells of MT1 KO mice (P < 0.05). The altered gene expression may be attributed to the suppression of oocyte maturation. In summary, melatonin protects against nuclear inhibition caused by HX and restores oocyte meiosis via MT1 by reducing the intracellular concentration of cAMP.

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Effect of oestrogen on mouse follicle growth and meiotic resumption

Zygote ◽

10.1017/s0967199421000708 ◽

2021 ◽

pp. 1-8

Author(s):

Heng Chi ◽

Zuowu Cao

Keyword(s):

Polar Body ◽

Follicular Development ◽

Germinal Vesicle ◽

Membrane Receptor ◽

Follicle Growth ◽

Germinal Vesicle Breakdown ◽

First Polar Body ◽

Two Phases

Summary Many studies have shown that oestrogen affects late follicular development, but whether oestrogen is involved in other aspects of folliculogenesis remains unclear. In this study, two antagonists of oestrogen, tamoxifen and G15, were used to determine the effects of oestrogen on folliculogenesis. Mouse preantral follicles and cumulus–oocyte complexes (COCs) were cultured in vitro. The results showed that follicle growth stimulated using pregnant mare serum gonadotrophin (PMSG) was inhibited using tamoxifen, whether in vivo or in vitro. The average diameters, the maximum diameters of follicles and the numbers of follicles with a diameter of more than 300 μm decreased significantly following a 4-day culture with tamoxifen. G15, the antagonist of oestrogen via the membrane receptor, did not change follicular growth stimulated by PMSG in vitro. Results of in vitro maturation of COCs showed that germinal vesicle breakdown (GVBD) occurred spontaneously (95.1%) after 2 h in culture, and the GVBD ratio changed little with the addition of either oestrogen or 10 μM G15. However, first polar body (PBI) extrusion was driven by oestrogen markedly and supplementation with 10 μM G15 inhibited PBI extrusion (82.4% vs 55.0%) significantly. These results demonstrated that oestrogen promotes follicle growth through the nuclear receptor during follicle growth and then triggers the transition of metaphase to anaphase through the membrane receptor during meiotic resumption. So oestrogen plays a progressive role in the two phases of follicle growth and oocyte meiotic resumption.

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Triphenyltin chloride induces spindle microtubule depolymerisation and inhibits meiotic maturation in mouse oocytes

Reproduction Fertility and Development ◽

10.1071/rd12332 ◽

2014 ◽

Vol 26 (8) ◽

pp. 1084 ◽

Cited By ~ 2

Author(s):

Yu-Ting Shen ◽

Yue-Qiang Song ◽

Xiao-Qin He ◽

Fei Zhang ◽

Xin Huang ◽

...

Keyword(s):

Polar Body ◽

Meiotic Maturation ◽

Dependent Manner ◽

Germinal Vesicle Breakdown ◽

Mouse Oocytes ◽

First Polar Body ◽

Triphenyltin Chloride ◽

Dose Dependent

Meiosis produces haploid gametes for sexual reproduction. Triphenyltin chloride (TPTCL) is a highly bioaccumulated and toxic environmental oestrogen; however, its effect on oocyte meiosis remains unknown. We examined the effect of TPTCL on mouse oocyte meiotic maturation in vitro and in vivo. In vitro, TPTCL inhibited germinal vesicle breakdown (GVBD) and first polar body extrusion (PBE) in a dose-dependent manner. The spindle microtubules completely disassembled and the chromosomes condensed after oocytes were exposed to 5 or 10 μg mL–1 TPTCL. γ-Tubulin protein was abnormally localised near chromosomes rather than on the spindle poles. In vivo, mice received TPTCL by oral gavage for 10 days. The general condition of the mice deteriorated and the ovary coefficient was reduced (P < 0.05). The number of secondary and mature ovarian follicles was significantly reduced by 10 mg kg–1 TPTCL (P < 0.05). GVBD decreased in a non-significant, dose-dependent manner (P > 0.05). PBE was inhibited with 10 mg kg–1 TPTCL (P < 0.05). The spindles of in vitro and in vivo metaphase II oocytes were disassembled with 10 mg kg–1 TPTCL. These results suggest that TPTCL seriously affects meiotic maturation by disturbing cell-cycle progression, disturbing the microtubule cytoskeleton and inhibiting follicle development in mouse oocytes.

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44 PRODUCTION OF LIVE PIGLETS AFTER CRYOPRESERVATION OF IMMATURE PORCINE OOCYTES

Reproduction Fertility and Development ◽

10.1071/rdv26n1ab44 ◽

2014 ◽

Vol 26 (1) ◽

pp. 136

Author(s):

T. Somfai ◽

K. Kikuchi ◽

K. Yoshioka ◽

F. Tanihara ◽

H. Kaneko ◽

...

Keyword(s):

Polar Body ◽

Petri Dish ◽

Developmental Competence ◽

Basic Medium ◽

High Survival ◽

Blastocyst Development ◽

Nuclear Maturation ◽

First Polar Body ◽

Vitrification Solution

Development to term of vitrified porcine follicular oocytes is reported in the present study. Immature cumulus-oocyte complexes (COC) were collected from slaughtered prepubertal gilts and were vitrified according to our method published recently (Somfai et al. 2013 J. Reprod. Dev., in press). Briefly, after pretreatment with 7.5 μg mL–1 of cytochalasin B (CB) for 30 min in modified NCSU-37 (a basic medium, BM) at 38.5°C, groups of 88 to 121 COC were equilibrated in a mixture of 2% ethylene glycol (EG), 2% propylene glycol (PG), and 7.5 μg mL–1 CB for 13 to 15 min. Then, COC were washed in vitrification solution (17.5% EG, 17.5% PG, 5% polyvinyl pyrrolidone, and 0.3 M trehalose in BM) and then dropped with 2 μL of vitrification solution onto the surface of aluminum foil floating on liquid nitrogen (LN2). Microdroplets (each containing 10–25 COC) were transferred into cryotubes. After storage in LN2 for 2 to 4 weeks, the oocytes were warmed by dropping the microdroplets directly into 2.5 mL of warming solution (0.4 M trehalose in BM) kept in a 35-mm Petri dish on a 42°C hotplate for less than 1 min. Then, the warming dish was placed on a 38°C hotplate and COC were consecutively transferred for 1-min periods into BM containing 0.2, 0.1, or 0.05 M trehalose at 38°C. The COC were matured in vitro for 44 h using porcine oocyte medium (POM) supplemented with 10% follicular fluid (Yoshioka et al. 2008 J. Reprod. Dev. 54, 208–213). Then, oocytes were denuded, and their live/dead status and nuclear maturation were determined by their morphology and the presence of the first polar body, respectively. To assess their developmental competence, vitrified and non-vitrified (control) oocytes were in vitro fertilized (IVF; Kikuchi et al. 2002 Biol. Reprod. 66, 1033–1041) and then in vitro cultured in porcine zygote medium-5 (PZM-5; Yoshioka et al. 2008 J. Reprod. Dev. 54, 208–213). Blastocyst rates were recorded on Days 5, 6, and 7 of culture (Day 0 = the day of IVF). The experiment was replicated 4 times. Data were analysed with 1-way ANOVA and the Tukey test. The results revealed that 86.4% (364/424) of oocytes survived after vitrification, which was significantly lower (P < 0.05) than that of controls [100% (326/326)]. Live oocytes in vitrified and control groups did not differ statistically in terms of nuclear maturation (63.9 v. 65.3%). Blastocyst rates of surviving vitrified oocytes were significantly lower compared with controls on Days 5 (2.4 v. 12.7%), 6 (4.8 v. 17.6%), and 7 (5.6 v. 18.4%). To test their ability to develop to term, 16 and 27 blastocysts on Day 5 developing from vitrified COC were transferred into 2 recipients. Both recipients became pregnant and farrowed a total of 10 live piglets (4 and 6 piglets, respectively). These data demonstrate that large groups of immature porcine oocytes could be cryopreserved by this method showing high survival and maturation rates. Furthermore, despite a low rate of blastocyst development, transfer of Day-5 blastocysts generated from vitrified oocytes resulted in piglet production for the first time in the world. Partially supported by JSPS and HAS under the Japan-Hungary Research Cooperative Program.

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Grape Seed Proanthocyanidin Ameliorates FB1-Induced Meiotic Defects in Porcine Oocytes

Toxins ◽

10.3390/toxins13120841 ◽

2021 ◽

Vol 13 (12) ◽

pp. 841

Author(s):

Wenhui Li ◽

Yijing He ◽

Hongyu Zhao ◽

Lei Peng ◽

Jia Li ◽

...

Keyword(s):

Oxidative Stress ◽

Polar Body ◽

Grape Seed ◽

Ros Generation ◽

Mrna Levels ◽

Blastocyst Development ◽

Cleavage Rate ◽

First Polar Body ◽

Grape Seed Proanthocyanidin

Fumonisin B1 (FB1), as the most prevalent and toxic fumonisin, poses a health threat to humans and animals. The cytotoxicity of FB1 is closely related to oxidative stress and apoptosis. The purpose of this study is to explore whether Grape seed proanthocyanidin (GSP), a natural antioxidant, could alleviate the meiotic maturation defects of oocytes caused by FB1 exposure. Porcine cumulus oocyte complexes (COCs) were treated with 30 μM FB1 alone or cotreated with 100, 200 and 300 μM GSP during in vitro maturation for 44 h. The results show that 200 μM GSP cotreatment observably ameliorated the toxic effects of FB1 exposure, showing to be promoting first polar body extrusion and improving the subsequent cleavage rate and blastocyst development rate. Moreover, 200 μM GSP cotreatment restored cell cycle progression, reduced the proportion of aberrant spindles, improved actin distribution and protected mitochondrial function in FB1-exposed oocytes. Furthermore, reactive oxygen species (ROS) generation was significantly decreased and the mRNA levels of CAT, SOD2 and GSH-PX were obviously increased in the 200 μM GSP cotreatment group. Notably, the incidence of early apoptosis and autophagy level were also significantly decreased after GSP cotreatment and the mRNA expression levels of BAX, CASPASE3, LC3 and ATG5 were markedly decreased, whereas BCL2 and mTOR were observably increased in the oocytes after GSP cotreatment. Together, these results indicate that GSP could exert significant preventive effects on FB1-induced oocyte defects by ameliorating oxidative stress through repairing mitochondrial dysfunction.

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355 INFLUENCE OF NITRIC OXIDE AND CYCLIC GMP SIGNALING PATHWAY ON THE IN VITRO MATURATION OF BOVINE OOCYTES: PRELIMINARY RESULTS

Reproduction Fertility and Development ◽

10.1071/rdv22n1ab355 ◽

2010 ◽

Vol 22 (1) ◽

pp. 334

Author(s):

K. R. L. Schwarz ◽

T. H. C. de Bem ◽

P. R. L. Pires ◽

L. G. Mesquita ◽

L. Remy ◽

...

Keyword(s):

Nitric Oxide ◽

Signaling Pathway ◽

Polar Body ◽

Calf Serum ◽

Guanosine Monophosphate ◽

No Donor ◽

Nuclear Maturation ◽

First Polar Body ◽

Bovine Oocytes

Nitric oxide (NO) is a chemical messenger generated by the activity of the nitric oxide synthase enzyme (NOS) and has been shown to be involved in oocyte maturation. NO is known to act through the guanylate cyclase (GC) signaling pathway, stimulating the production of cyclic guanosine monophosphate (cGMP), which in turn activates protein kinase G (PKG). The objective of the present study was to investigate the involvement of NO and GC/cGMP/PKG pathway on the IVM of bovine oocytes. Slaughterhouse ovaries were transported to the laboratory and oocytes were aspirated from 2 to 8 mm follicles. Oocytes were submitted to IVM (TCM-199+10% fetal calf serum + hormones) for 24 h (38.5°C and 5% CO2 in air) and were assessed for nuclear maturation by acetic-orcein (1%) staining. Maturation rates were analyzed by ANOVA. Five replicates were performed with 20 oocytes per group per replicate. When the oocytes were matured with the NO donor [(0, 10-9, 10-8 and 10-7M S-nitroso-N-acteyl-D,L- penicillamine (SNAP)] germinal vesicle break down (GVBD) rates after 7 h in IVM were 36, 31, 42, and 24%, respectively (P > 0.05). Maturation rates after 24 h IVM ranged from 80 to 85% (P > 0.05). The inhibition of GC [(0, 0.1, 10, and 100 μM 1, H-[1, 2, 4]oxadiazole[4, 3-a]quinoxalon-1-one (ODQ)] and PKG (0, 1, 10, and 100 μM KT5823) did not affect (P > 0.05) the ability of oocytes to form the first polar body (average of 83 and 88%, respectively). When the cGMP-analogue (0, 1, 2, and 4 mM 8-Bromo-cGMP) and the GC-stimulator (0, 5, 10, and 50 μM Protoporphyrin IX) were used during IVM, maturation rates were over 85% in all groups (P > 0.05). To confirm the lack of effect of the inhibitors, another evaluation with higher concentrations of inhibitors in semi-defined IVM medium (TCM-199 + 0.04% BSA) was carried out. Maturation rates were 70 to 75% (P > 0.05) with ODQ and 57 to 76% (P > 0.05) with KT5823. The evaluation with the GC stimulator and the cGMP analogue in semi-defined medium is currently underway. In conclusion, under the conditions studied, the GC/cGMP/PKG signaling pathway is not involved in the nuclear maturation of bovine oocytes. Supported by FAPESP, Brazil.

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61 THE EFFECTS OF COLLECTION SEASON AND STORAGE DURATION IN LIQUID NITROGEN ON POST-WARMING SURVIVAL AND NUCLEAR MATURATION OF IMMATURE PORCINE OOCYTES PRESERVED BY SOLID SURFACE VITRIFICATION

Reproduction Fertility and Development ◽

10.1071/rdv27n1ab61 ◽

2015 ◽

Vol 27 (1) ◽

pp. 123

Author(s):

T. Nagai ◽

T. Somfai ◽

N. T. Men ◽

H. Kabeko ◽

J. Noguchi ◽

...

Keyword(s):

Liquid Nitrogen ◽

Solid Surface ◽

In Vitro Maturation ◽

Polar Body ◽

Storage Duration ◽

Nuclear Maturation ◽

First Polar Body ◽

Duration Of Storage ◽

And Storage

We investigated the effects of collection season and storage duration of vitrified porcine oocytes in liquid nitrogen (LN2) on their survival and maturation ability after warming. A total of 3338 cumulus-enclosed oocytes were vitrified using solid surface vitrification, preserved, and warmed according to previous report (Somfai et al. 2014 PLoS One 9, e97731) in 26 occasions between October 2012 and March 2014. Vitrified oocytes were stored in LN2 for various durations from 0 (vitrified but without storage) to 243 days. The date of preservation and length of storage (days) of vitrified oocytes in LN2 were recorded. Warming of vitrified oocytes was conducted on a hotplate set at 42°C. After warming, oocytes were subjected to in vitro maturation according to Kikuchi et al. (2002 Biol. Reprod. 66, 1033–1041). Then oocytes were denuded and their live/dead status and nuclear maturation were assessed under stereo microscope based on their morphology and the presence of the first polar body. After linear regression analysis, it was found that there was no correlation between the duration of storage of vitrified oocytes in LN2 for up to 243 days and their survival rate after warming (R = 0.254; P = 0.210) or the maturation rate of surviving oocytes (R = 0.147; P = 0.471). Vitrification during spring (March 1–May 31) resulted in significantly higher rates of survived oocytes compared with vitrification during winter (December 1–February 28; 86.9 and 73.1%, respectively; P < 0.05), whereas the mean survival rates of oocytes vitrified during summer (June 1–August 31; 79.0%) and autumn (September 1–November 31; 81.9%) did not differ significantly from those of other seasons (ANOVA). After in vitro maturation, nuclear maturation of surviving oocytes did not differ significantly among oocytes vitrified at different seasons (ranging between 59.1 and 67.8%). The results indicate that the oocyte collection season affects survival of vitrified oocytes, whereas storage duration in LN2 does not affect this parameter. Furthermore, nuclear maturation of oocytes that survive after vitrification and warming is not affected by their collection season and storage length.This work was supported by JSPS KAKENHI Grant Number 26870839.

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Glycogen synthase kinase 3B in bovine oocytes and granulosa cells: possible involvement in meiosis during in vitro maturation

Reproduction ◽

10.1530/rep-09-0136 ◽

2009 ◽

Vol 138 (2) ◽

pp. 235-246 ◽

Cited By ~ 25

Author(s):

Svetlana Uzbekova ◽

Mohamad Salhab ◽

Christine Perreau ◽

Pascal Mermillod ◽

Joëlle Dupont

Keyword(s):

Granulosa Cells ◽

Map Kinases ◽

Glycogen Synthase ◽

Polar Body ◽

Germinal Vesicle ◽

Glycogen Synthase Kinase ◽

Aurora A Kinase ◽

Germinal Vesicle Breakdown ◽

First Polar Body

Glycogen synthase kinase 3 (GSK3) regulates cellular metabolism and cell cycle via different signalling pathways. In response to insulin and growth factors GSK3 is serine-phosphorylated and inactivated. We analysed GSK3B expression and activation in bovine cumulus cells (CC) and oocytes at different meiotic stagesin vitroin parallel with MAP kinases ERK (MAPK3/MAPK1) and p38 (MAPK14). GSK3B localised to cytoplasm in granulosa cells and in oocytes throughout folliculogenesis. In mature metaphase-II (MII) oocytes, GSK3B was concentrated to the region of midzone between the oocyte and the first polar body, as well as active phospho-Thr Aurora A kinase (AURKA). Duringin vitromaturation (IVM), in oocytes, phospho-Ser9-GSK3B level increased as well as phospho-MAPK3/MAPK1, while phospho-MAPK14 decreased. In CC, phospho-MAPK14 increased upon germinal vesicle breakdown (GVBD)/metaphase-I (MI) and then decreased during transition to MII. Administration of inhibitors of GSK3 activity (lithium chloride or 2′Z,3′E -6-bromoindirubin-3′-oxime) rapidly increased phospho-Ser9-GSK3B, and led to transient decrease of phospho-MAPK3/MAPK1 and to durable enhancing of phospho-MAPK14 in granulosa primary cell culture. GSK3 inhibitors during IVM diminished cumulus expansion and delayed meiotic progression. In cumulus, phospho-MAPK14 level was significantly higher in the presence of inhibitors, comparing with control, through the time of MI/MII transition. In oocytes, phospho-GSK3B was increased and phospho-MAPK3/MAPK1 was decreased before GVBD and oocytes were mainly arrested at MI. Therefore, GSK3B might regulate oocyte meiosis, notably MI/MII transition being the part of MAPK3/1 and MAPK14 pathways in oocytes and CC. GSK3B might be also involved in the local activation of AURKA that controls this transition.

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Thioglycolic acid inhibits mouse oocyte maturation and affects chromosomal arrangement and spindle configuration

Toxicology and Industrial Health ◽

10.1177/0748233708095862 ◽

2008 ◽

Vol 24 (4) ◽

pp. 227-234 ◽

Cited By ~ 8

Author(s):

SY Hou ◽

L Zhang ◽

K Wu ◽

L Xia

Keyword(s):

Thioglycolic Acid ◽

Polar Body ◽

Germinal Vesicle ◽

Germinal Vesicle Breakdown ◽

Chromosomal Arrangement ◽

First Polar Body ◽

Inverted Microscope ◽

Polar Body Formation ◽

Spindle Elongation

Previous studies have shown that thioglycolic acid (TGA) leads to potential reproductive toxicology. To clarify the exact effects of this compound on reproduction, mice oocytes were treated with different TGA doses. At the end of the culture period, the nuclear status of mice oocytes was assessed under an inverted microscope. After immunofluorescence staining, the chromosomal arrangement and spindle configuration of oocytes were evaluated. The results indicated that TGA decreases the percentage of first polar body formation but does not influence that of germinal vesicle breakdown. TGA induces abnormal chromosomal arrangement and spindle elongation. In conclusion, TGA inhibits in-vitro maturation of mice oocytes and affects chromosomal arrangement and spindle configuration. Furthermore, it probably interferes with biochemical changes that occur during meiosis, resulting in aberrant development.

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Oxygen tension and oocyte density during in vitro maturation affect the in vitro fertilization of bovine oocytes

Semina Ciências Agrárias ◽

10.5433/1679-0359.2015v36n6supl2p4277 ◽

2015 ◽

Vol 36 (6Supl2) ◽

pp. 4277 ◽

Cited By ~ 2

Author(s):

Angelo Bertani Giotto ◽

Daniela Dos Santos Brum ◽

Francielli Weber Santos ◽

Antonio Carlos Galarça Guimarães ◽

Cibele Garcia Moreira Gonçalves ◽

...

Keyword(s):

Antioxidant Activity ◽

Oxygen Tension ◽

Polar Body ◽

Ros Production ◽

Low Oxygen ◽

Nuclear Maturation ◽

First Polar Body ◽

Cytoplasmic Maturation ◽

Bovine Oocytes

Oocyte maturation is the key factor affecting the fertilization and embryonic development. Factors such as oocyte density and oxygen tension can directly influence the IMV. Thus, the objective of this study was to evaluate the effect of the association of oxygen tensions (5% or 20%) with different oocyte densities (1:10?l or 1:20?l) in the in vitro maturation (IVM) of bovine oocytes on maturation and fertilization rates, ROS production and antioxidant activity. Three experiments were performed with bovine oocytes that were obtained from slaughterhouse ovaries. After selection, the oocytes were randomly distributed in four treatments: 1:10/5%; 1:10/20%; 1:20/5%and 1:20/20% for each experiment. In experiment I, nuclear maturation status and cytoplasmic maturation were evaluated through detection of the first polar body by immunofluorescence and the mitochondrial reorganization assay. In experiment II, ROS production and antioxidant activity were analyzed in oocytes and IVM medium after 24 h of maturation through detection of ROS, reduced glutathione (GSH) and Superoxide dismutase activity by spectrofluorimetric methods. In experiment III, fertilization was evaluated through pronucleus formation, sperm penetration with or without decondensation and polyspermy rates by immunofluorescence. In experiment I, the nuclear maturation and cytoplasmic maturation were similar among treatments (P>0.05). In experiment II, reactive oxygen species in oocytes were elevated in treatments with low oxygen tension which was independent of oocyte density (P<0.05). Additionally, ROS levels in IVM medium were higher in treatments with high oocyte density by volume of medium, which was independent of oxygen tension (P<0.05). In Experiment III, the fertilization and penetration rates were higher in the treatment with 20% oxygen tension and high oocyte density (P<0.05). Furthermore, a high incidence of polyspermy was observed in groups with high oxygen tension and low oocyte density (P<0.05). In conclusion, the results of this study indicate an interaction between oxygen tension and oocyte density, which increases ROS production in certain associations and subsequently influences the rates of in vitro fertilization of bovine oocytes. The improved rates of IVF were obtained when IVM was conducted using 20% oxygen tension and high oocyte density (1:20 ul).

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Translocation of phospho-protein kinase Cs implies their roles in meiotic-spindle organization, polar-body emission and nuclear activity in mouse eggs

Reproduction ◽

10.1530/rep.1.00336 ◽

2005 ◽

Vol 129 (2) ◽

pp. 229-234 ◽

Cited By ~ 13

Author(s):

Zhen-Yu Zheng ◽

Qing-Zhang Li ◽

Da-Yuan Chen ◽

Heide Schatten ◽

Qing-Yuan Sun

Keyword(s):

Protein Kinase ◽

Polar Body ◽

Germinal Vesicle ◽

Mouse Oocyte ◽

Meiotic Spindle ◽

Germinal Vesicle Breakdown ◽

Nuclear Activity ◽

Spindle Poles ◽

Oocyte Meiosis ◽

First Polar Body

The protein kinase Cs (PKCs) are a family of Ser/Thr protein kinases categorized into three subfamilies: classical, novel, and atypical. The phosphorylation of PKC in germ cells is not well defined. In this study, we described the subcellular localization of phopho-PKC in the process of mouse oocyte maturation, fertilization, and early embryonic mitosis. Confocal microscopy revealed that phospho-PKC (pan) was distributed abundantly in the nucleus at the germinal vesicle stage. After germinal vesicle breakdown, phospho-PKC was localized in the vicinity of the condensed chromosomes, distributed in the whole meiotic spindle, and concentrated at the spindle poles. After metaphase I, phospho-PKC was translocated gradually to the spindle mid-zone during emission of the first polar body. After sperm penetration and electrical activation, the distribution of phospho-PKC was moved from the spindle poles to the spindle mid-zone. After the extrusion of the second polar body (PB2) phospho-PKC was localized in the area between the oocyte and the PB2. In fertilized eggs, phospho-PKC was concentrated in the pronuclei except for the nucleolus. Phospho-PKC was dispersed after pronuclear envelope breakdown, but distributed on the entire spindle at mitotic metaphase. The results suggest that PKC activation may play important roles in regulating spindle organization and stabilization, polar-body extrusion, and nuclear activity during mouse oocyte meiosis, fertilization, and early embryonic mitosis.

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