Chlorothalonil exposure compromised mouse oocyte in vitro maturation through inducing oxidative stress and activating MAPK pathway.

Chlorothalonil (CTL) is widely used in agricultural production and antifoulant additive globally due to its broad spectrum and non-systemic properties, resulting in its widespread existence in foods, soil and water. Extensive evidence demonstrated that exposure to CTL induced adverse effects on organisms and in particular its reproductive toxicity has been attracted public concern. However, the influences of CTL on oocyte maturation is mysterious so far. In this study, we documented the toxic effects of CTL on oocyte in vitro maturation and the related underlying mechanisms. Exposure to CTL caused continuous activation of spindle assembly checkpoints (SAC) which in turn compromised meiotic maturation in mouse oocyte, featured by the attenuation of polar body extrusion (PBE). Detection of cytoskeletal dynamics demonstrated that CTL exposure weakened the acetylation level of α-tubulin and impaired meiotic spindle apparatus, which was responsible for the aberrant state of SAC. Meanwhile, exposure to CTL damaged the function of mitochondria, inducing the decline of ATP content and the elevation of reactive oxygen species (ROS), which thereby induced early apoptosis and DNA damage in mouse oocytes. In addition, exposure to CTL caused the alteration of the level of histone H3 methylation, indicative of the harmful effects of CTL on epigenetic modifications in oocytes. Further, the CTL-induced oxidative stress activated mitogen-activated protein kinase (MAPK) pathway and injured the maturation of oocytes. In summary, exposure to CTL damaged mouse oocyte in vitro maturation via destroying spindle assembly, inducing oxidative stress and triggering MAPK pathway activation.

Propyl gallate exposure affects the mouse 2-cell stage embryonic development through inducing oxidative stress and autophagy.

Propyl gallate (PG), owing to its exceptional antioxidant properties, is extensively used in industries such as food processing. The potential harmful impacts of PG have sparked concern among people. It has been reported that exposure of PG has certain reproductive toxicity, which can affect the maturation of mouse oocytes and induce testicular dysfunction. However, its impact on early embryonic development is still unclear. In this study, we explored the toxic effects and potential mechanisms of PG on mouse 2-cell stage embryonic development. The results showed that exposure of PG can decrease the development of 2-cell stage embryos and repress the development of 4-cell stage embryos. Further study found that PG could induce intracellular oxidative stress and the accumulation of DNA damage in 2-cell stage embryos. Moreover, exposure of PG impaired the function of mitochondria and lysosomes in 2-cell stage embryos, thereby triggering the occurrence of autophagy. In addition, exposure of PG altered the epigenetic modification of 2-cell stage embryos, displaying a decreased level of DNA methylation and an increased level of H3K4me3. In summary, our results indicated that exposure of PG can damage the development of mouse 2-cell stage embryos by inducing oxidative stress, DNA damage, and autophagy, and altering epigenetic modification.

Caseinolytic mitochondrial matrix peptidase X is essential for homologous chromosome synapsis and recombination during meiosis of male mouse germ cells.

ABSTRACT: Meiosis is the process of producing haploid gametes through a series of complex chromosomal events and the coordinated action of various proteins. The mitochondrial protease complex (ClpXP), which consists of caseinolytic mitochondrial matrix peptidase X (ClpX) and caseinolytic protease P (ClpP) and mediates the degradation of misfolded, damaged, and oxidized proteins, is essential for maintaining mitochondrial homeostasis. ClpXP has been implicated in meiosis regulation, but its precise role is currently unknown. In this study, we engineered an inducible male germ cell-specific knockout caseinolytic mitochondrial matrix peptidase X (ClpxcKO) mouse model to investigate the function of ClpX in meiosis. We found that disrupting Clpx in male mice induced germ cell apoptosis and led to an absence of sperm in the epididymis. Specifically, it caused asynapsis of homologous chromosomes and impaired meiotic recombination, resulting in meiotic arrest in the zygotene-to-pachytene transition phase. The loss of ClpX compromised the double-strand break (DSB) repair machinery by markedly reducing the recruitment of DNA repair protein RAD51 homolog 1 (RAD51) to DSB sites. This dysfunction may be due to an insufficient supply of energy from the aberrant mitochondria in ClpxcKO spermatocytes, as discerned by electron microscopy. Furthermore, ubiquitination signals on chromosomes and the expression of oxidative phosphorylation subunits were both significantly attenuated in ClpxcKO spermatocytes. Taken together, we propose that ClpX is essential for maintaining mitochondrial protein homeostasis and ensuring homologous chromosome pairing, synapsis, and recombination in spermatocytes during meiotic prophase I.

Curcumin alleviates bisphenol AF-induced oxidative stress and apoptosis in caprine endometrial epithelial cells via the Nrf2 signaling pathway.

Bisphenol AF (BPAF), a BPA-substitute, has been widely used in industrial compounds throughout the world. Several studies have shown that BPAF has endocrine interference and reproductive toxicity. However, the toxic effects of BPAF on pregnancy and placenta of goats are still unclear. Therefore, the objective of this study was to reveal the toxic effect of BPAF by using an in vitro culture model of caprine endometrial epithelial cells (EECs) and further attempted to alleviate the toxicity by curcumin pretreatment. The results showed that BPAF induces significant effects on EECs, including decreased cell viability and mitochondrial membrane potential (△ψm), elevating intracellular reactive oxygen species (ROS), promoting cell apoptosis through upregulating the expression of Bax, Cytochrome c, and downregulating the expression of Bcl-2. Meanwhile, BPAF induced dysregulation of oxidative stress by increasing the levels of malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) but decreasing the activities of superoxide dismutase (SOD). However, curcumin pretreatment could significantly attenuate BPAF-induced toxic effects in EECs. Further study revealed that BPAF treatment could activate mitogen-activated protein kinase (MAPK) pathway and nuclear factor-erythroid 2-related factor 2 (Nrf2) expression, but curcumin pretreatment significantly inhibited the activation of MAPK signal pathway and Nrf2 expression induced by BPAF. Overall, this study indicated that curcumin could prevent BPAF-induced EECs cytotoxicity, which provides a potential therapeutic strategy for female infertility associated with BPAF exposure.

High-dose synthetic phenolic antioxidant propyl gallate impairs mouse oocyte meiotic maturation through inducing mitochondrial dysfunction and DNA damage.

Propyl gallate (PG) is one of the most widely used antioxidants in food products, cosmetics and pharmaceutical industries. Increased research has suggested that exposure to PG influences reproductive health in humans and animals. However, until now, it has not yet been confirmed whether PG would impact oocyte quality. In this study, the hazardous effects of PG on oocyte meiotic maturation were investigated in mice. The findings showed that PG exposure compromises oocyte meiosis by inducing mitochondrial stress which activates apoptosis to trigger oocyte demise. Moreover, DNA damage was significantly induced in PG-treated oocytes, which might be another cause of oocyte developmental arrest and degeneration. Besides, the level of histone methylation (H3K27me2 and H3K27me3) in oocyte was also significantly increased by PG exposure. Furthermore, PG-induced oxidative stress was validated by the increased level of reactive oxygen species (ROS), which might be the underlying reason for these abnormities. In conclusion, the foregoing findings suggested that PG exposure impaired oocyte meiotic maturation by yielding mitochondrial stress to activate apoptosis, inducing DNA damage and oxidative stress, and altering histone methylation level.

Acute exposure of triclocarban affects early embryo development in mouse through disrupting maternal-to-zygotic transition and epigenetic modifications.

Triclocarban (TCC) is a broad-spectrum antibacterial agent used globally, and high concentrations of this harmful chemical exist in the environment. The human body is directly exposed to TCC through skin contact. Moreover, TCC is also absorbed through diet and inhaled through breathing, which results in its accumulation in the body. The safety profile of TCC and its potential impact on human health are still not completely clear; therefore, it becomes imperative to evaluate the reproductive toxicity of TCC. Here, we explored the effect of TCC on the early embryonic development of mice and its associated mechanisms. We found that acute exposure of TCC affected the early embryonic development of mice in a dose-dependent manner. Approximately 7600 differentially expressed genes (DEGs) were obtained by sequencing the transcriptome of 2-cell mouse embryos; of these, 3157 genes were upregulated and 4443 genes were downregulated in the TCC-treated embryos. GO and KEGG analysis revealed that the enriched genes were mainly involved in redox processes, RNA synthesis, DNA damage, apoptosis, mitochondria, endoplasmic reticulum, Golgi apparatus, cytoskeleton, peroxisome, RNA polymerase, and other components or processes. Moreover, the Venn analysis showed that the zygotic genome activation (ZGA) was affected and the degradation of maternal effector genes was inhibited. TCC induced changes in the epigenetic modification of 2-cell embryos. The level of DNA methylation increased significantly. Further, the levels of H3K27ac, H3K9ac, and H3K27me3 histone modifications decreased significantly, whereas those of H3K4me3 and H3K9me3 modifications increased significantly. Additionally, TCC induced oxidative stress and DNA damage in the 2-cell embryos. In conclusion, acute exposure of TCC affected early embryo development, destroyed early embryo gene expression, interfered with ZGA and maternal gene degradation, induced changes in epigenetic modification of early embryos, and led to oxidative stress and DNA damage in mouse early embryos.

Bromoacetic acid impairs mouse oocyte in vitro maturation through affecting cytoskeleton architecture and epigenetic modification.

As a major public health achievement, disinfection of drinking water significantly decreases outbreaks of waterborne disease, but produces drinking water disinfection by-products (DBPs) unfortunately. The haloacetic acids (HAAs) including bromoacetic acid (BAA), the second major class of DBPs, are considered as a global public health concern. BAA has been identified as cytotoxic, genotoxic, mutagenic, carcinogenic, and teratogenic in somatic cells. However, the toxic effects of BAA on oocyte maturation remain obscure. Herein, we documented that exposure to BAA compromised mouse oocyte maturation in vitro, causing blocked polar body extrusion (PBE). Meiotic progression analysis demonstrated that exposure to BAA induced the activated spindle assembly checkpoint (SAC) mediated metaphase I (MI) arrest in oocytes. Further study revealed that exposure to BAA resulted in the hyperacetylation of α-tubulin, disrupting spindle assembly and chromosome alignment, which is responsible for the activation of SAC. Besides, the organization of actin, the other major component of cytoskeleton in oocytes, was disturbed after BAA exposure. In addition, exposure to BAA altered the status of histone H3 methylation and 5 mC, indicative of the damaged epigenetic modifications. Moreover, we found that exposure to BAA induced DNA damage in a dose-dependent manner in oocytes. Collectively, our study evidenced that exposure to BAA intervened mouse oocyte maturation via disrupting cytoskeletal dynamics, damaging epigenetic modifications and inducing accumulation of DNA damage.

Zinc pyrithione exposure compromises oocyte maturation through involving in spindle assembly and zinc accumulation.

Zinc Pyrithione (ZPT), a Food and Drug Administration (FDA) approved chemical, is widely used for topical antimicrobials and cosmetic consumer products, including anti-dandruff shampoos. ZPT and its degraded byproducts have detected in large quantities in the environment, and identified to pose healthy risks on aquatic organisms and human. However, so far, knowledge about ZPT effects on female reproduction, particularly oocyte maturation and quality, is limited. Herein, we investigated the adverse impact of ZPT on mouse oocyte maturation and quality in vitro and found exposure to ZPT significantly compromises oocyte maturation. The results revealed that ZPT disturbed the meiotic cell cycle by impairing cytoskeletal dynamics, kinetochore-microtubule attachment (K-MT), and causing spindle assembly checkpoints (SAC) continuous activation. Further, we observed the microtubule-organizing centers (MTOCs) associated proteins p-MAPK and Aurora-A were disrupted in ZPT-treated oocytes, signified by decreased expression and abnormal localization, responsible for the severe cytoskeletal defects. In addition, ZPT exposure induced a significant increase in the levels of H3K9me2, H3K9me3, H3K27me1, and H3K27me3, suggesting the alterations of epigenetic modifications. Moreover, the accumulation of zinc ions (Zn2+) was observed in ZPT-treated oocytes, which was detrimental because overmuch intracellular Zn2+ disrupted oocyte meiosis. Finally, these above alterations impaired spindle organization and chromosome alignment in metaphase-II (MII) oocytes, indicative of damaged oocytes quality. In conclusion, ZPT exposure influenced oocyte maturation and quality via involvement in MTOCs-associated proteins mediated spindle defects, altered epigenetic modifications and zinc accumulation.

Global change of microRNA expression induced by vitamin C treatment on immature boar Sertoli cells.

Sertoli cells (SCs), the only somatic constituent of the testicular seminiferous epithelium, are vital to spermatogenesis. We previously found that vitamin C (ascorbic acid, AA) can reprogram the transcriptome, and promote the proliferation and reproductive function of pig immature SCs (iSCs). However, the global change of microRNAs (miRNA) expression and its effect on pig iSCs as induced by vitamin C treatment is still unknown. Here, we performed small RNA sequencing on pig iSCs after 250 µM AA2P (l-ascorbic acid 2-phosphate sesquimagnesium salt hydrate) treatment for 36h. Total number of detected miRNAs ranged from 326 to 335 known, and 400-570 novel miRNAs. Of the top ten highly expressed miRNAs, we found that 8 were common (miR-21-5p, let-7i-5p, miR-30a-5p, let-7f-5p, let-7g, miR-100, miR-10a-5p and miR-30d), which were predicted to target mRNAs involved in cell development and differentiation. We identified 78 differentially expressed (DE) miRNAs (|log2 (Fold Change)|≥1; Padj.<0.05), including 7 known and 71 novel miRNAs. We further selected 13 highly and stably expressed DE miRNAs (4 up-regulated: miR-184, novel-miR-610, novel-miR-316 and novel-miR-1274; 9 down-regulated: miR-222, miR-221-5p, miR-221-3p, miR-210, miR-146b, miR-146a-5p, novel-miR-182, novel-miR-1088 and novel-miR-1016), and performed integrated analysis on the miRNA-mRNA regulatory network. DE mRNAs negatively targeted by these 13 DE miRNAs were enriched in multiple GO and KEGG signaling pathways (e.g. pyruvate and steroid metabolic processes, developmental process in reproduction, response to oxidative stress, Glycolysis/Gluconeogenesis and HIF-1). We validated 8 DE miRNAs and their 12 DE mRNA targets, most of them showed expression patterns consistent with (mi)RNA-seq results. Taken together, our findings demonstrate that vitamin C could induce the global change of miRNAs, which possibly regulate cell proliferation, energy metabolism and male reproduction as induced by vitamin C treatment on pig iSCs.

Bisphenol F exposure affects mouse oocyte in vitro maturation through inducing oxidative stress and DNA damage.

Bisphenol F (BPF), a substitute for bisphenol A (BPA), is progressively used to manufacture various consumer products. Despite the established reproductive toxicity of BPF, the underlying mechanisms remain to elucidate. This in-vitro study deep in sighted the BPF toxicity on mouse oocyte meiotic maturation and quality. After treating oocytes with BPF (300 µM), the oocyte meiotic progression was blocked, accentuated by a reduced rate in the first polar body extrusion (PBE). Next, we illustrated that BPF induced α-tubulin hyper-acetylation disrupted the spindle assembly and chromosome alignment. Concurrently, BPF resulted in severe oxidative stress and DNA damage, which triggered the early apoptosis in mouse oocytes. Further, altered epigenetic modifications following BPF exposure were proved by increased H3K27me3 levels. Concerning the toxic effects on spindle structure, oxidative stress, and DNA damage in mouse oocytes, BPF toxicity was less severe to oocyte maturation and spindle structure than BPA and induced low oxidative stress. However, compared with BPA, oocytes treated with BPF were more prone to DNA damage, indicating not less intense or even more severe toxic effects of BPF than BPA on some aspects of oocytes maturation. In brief, the present study established that like wise to BPA, BPF could inhibit meiotic maturation and reduce oocyte quality, suggesting it is not a safe substitute for BPA.

WDR62 regulates mouse oocyte meiotic maturation related to p-JNK and H3K9 trimethylation.

WDR62 (WD40-repeat protein 62) participates in diverse biological process, especially mitotic spindle organization via regulating centriole biogenesis and the function of centriole-associated protein. However, the role of WDR62 exerts in spindle assembly and meiotic progression control in oocytes lacking typical centrosomes remains obscure. In a previous study, we reported that WDR62 is involved in spindle migration and asymmetric cytokinesis in mouse oocyte meiosis. In the current study, another novel function of WDR62 regulating cell cycle progression through meiotic spindle formation during oocyte meiotic maturation was found. Knockdown of WDR62 through siRNA microinjection disrupted the meiotic cell cycle and induced metaphase-I (MI) arrest coupled with severe spindle abnormality, chromosome misalignment, and aneuploid generation. Moreover, WDR62 depletion induced defective kinetochore-microtubule attachments (K-MT) and activated spindle assembly checkpoint (SAC), which could trigger the arrest of meiotic progression. Further study demonstrated that depletion of WDR62 was associated with an aberrant location of p-JNK and reduced its expression level; concomitantly, status of H3K9 trimethylation was also altered. In addition, phenotypes similar to WDR62 depletion were observed during the function-loss analysis of p-JNK using a specific inhibitor (SP600125), which signifies that WDR62 is important for spindle organization and meiotic progression, and this function might be via its regulation of p-JNK. In conclusion, this study revealed that WDR62 functions in multiple ways during oocyte meiotic maturation, which could be related to p-JNK and H3K9 trimethylation.

Identification of lncRNAs involved in maternal-to-zygotic transition of in vitro-produced porcine embryos by single-cell RNA-seq.

Long non-coding RNAs (lncRNAs) function through multiple tiers of molecular circuits and are vital to gamete maturation and early embryo development. However, in pig early embryos, identification and expression dynamics of lncRNAs remain less studied. Here, we systematically analysed the expression dynamics of lncRNAs based on our previously published single-cell RNA-seq data from pig mature oocytes (GSE160334), and single blastomeres biopsied from pig in vitro fertilized (IVF) and early parthenogenetically activated (PA) embryos (1- to 8-cell stages; GSE164812). With the progression of embryo development, the total number of expressed lncRNAs gradually decreased and showed great variation at each developmental stage for both IVF and PA groups. Consecutive stage pairwise comparison of MII oocytes, 1-cell zygotes, 2-cell, 4-cell and 8-cell IVF embryos identified 151, 245, 1119 and 188 differentially expressed (DE) lncRNAs, including 119, 80, 867, 77 up-regulated and 32, 165, 252, 111 down-regulated, while 289, 437, 895 and 495 DE lncRNAs (141, 89, 768, 97 up-regulated and 148, 348, 127, 398 down-regulated) were identified in PA embryos at the same stages. The DE lncRNAs identified within IVF embryos were much different from that identified within PA embryos, showing embryo type-specific manner. Further cross-comparison between PA and IVF embryos identified 184, 656, 2502 and 266 DE lncRNAs for the 1- to 8-cell embryo stages, respectively. Further GO and KEGG enrichment analysis of DE mRNAs targeted by DELs indicated that different signalling pathways were involved in maternal-only and bi-parental embryo development. Collectively, comparative profiling of lncRNA expression dynamics between pig IVF and PA embryos provides a valuable resource, to investigate further regulatory mechanisms of lncRNAs associated with ZGA and maternal RNA decay during early embryo development.

Benzophenone-3 breaches mouse Sertoli cell barrier and alters F-actin organization without evoking apoptosis.

Benzophenone-3 (BP-3), one of the most commonly utilized ultraviolet filters in personal care products, has aroused public concern in recent years for its high chances of human exposure. Previous studies have found that BP-3 can impair testes development and spermatogenesis, but the targets of BP-3 are still unknown. In this study, primary Sertoli cells from 20-day-old mice were treated in vitro with 0-100 µM BP-3 for 24 h to identify its toxicity on Sertoli cells and Sertoli cell barrier. Results demonstrated that BP-3 could induce a notable change in cell morphology and impair Sertoli cell viability. The analysis of transepithelial electrical resistance showed that the integrity of the Sertoli cell barrier was destroyed by BP-3 (100 µM). Some structural proteins of the barrier including ZO-1, Occludin, and Connexin43 were lower expressed and the localization of basal ectoplasmic specializations protein ß-catenin was altered because of BP-3 treatment. Further exploration suggested that BP-3 led to Sertoli cell F-actin disorganization by affecting the expression of Rictor, a key component of the mTORC2 complex. Moreover, although increased DNA damage marker γH2A.X was observed in the treatment group, the cell apoptosis rate was changeless which was further confirmed by increased BAX and stable Bcl-2 (two primary apoptosis regulating proteins). In conclusion, this study revealed that BP-3 had the potential to perturb the Sertoli cell barrier through altered junction proteins and disorganized F-actin, but it could hardly evoke Sertoli cell apoptosis.

Gossypol exposure induces mitochondrial dysfunction and oxidative stress during mouse oocyte in vitro maturation.

Gossypol is a yellow natural polyphenolic compound extracted from the seeds, leaves, stems, and flower buds of the cotton plant. Several studies have shown that exposure to gossypol impacts reproductive health in both humans and animals. However, whether gossypol exposure would influence oocyte quality has not yet been determined. Here, we studied the effects of gossypol on the meiotic maturation of mouse oocytes in vitro. The results revealed that gossypol exposure did not affect germinal vesicle breakdown (GVBD) but significantly reduced polar body extrusion (PBE) rates. Moreover, we observed meiotic spindle organization and chromosome alignment were entirely disturbed after gossypol exposure. Further, gossypol exposure also caused mitochondrial dysfunction and abruptly decreased the levels of cellular ATP, and diminished the mitochondrial membrane potential (MMP). Accordingly, gossypol-induced oxidative stress was confirmed through an increased level of reactive oxygen species (ROS). Early apoptosis incidence also increased as identified by positive Annexin-V signaling. Collectively, the above findings provide evidence that gossypol exposure impaired oocyte meiotic maturation, disturbed spindle structure and chromosome dynamics, disrupted mitochondrial function, induced oxidative stress, and triggered early apoptosis. These findings emphasize gossypol's adverse effects on oocyte maturation and thus on female fertility.

Ribonucleic Acid Export 1 Is a Kinetochore-Associated Protein That Participates in Chromosome Alignment in Mouse Oocytes.

Ribonucleic acid export 1 (Rae1) is an important nucleoporin that participates in mRNA export during the interphase of higher eukaryotes and regulates the mitotic cell cycle. In this study, small RNA interference technology was used to knockdown Rae1, and immunofluorescence, immunoblotting, and chromosome spreading were used to study the role of Rae1 in mouse oocyte meiotic maturation. We found that Rae1 is a crucial regulator of meiotic maturation of mouse oocytes. After the resumption of meiosis (GVBD), Rae1 was concentrated on the kinetochore structure. The knockdown of Rae1 by a specific siRNA inhibited GVBD progression at 2 h, finally leading to a decreased 14 h polar body extrusion (PBE) rate. However, a comparable 14 h PBE rate was found in the control, and the Rae1 knockdown groups that had already undergone GVBD. Furthermore, we found elevated PBE after 9.5 h in the Rae1 knockdown oocytes. Further analysis revealed that Rae1 depletion significantly decreased the protein level of securin. In addition, we detected weakened kinetochore-microtubule (K-MT) attachments, misaligned chromosomes, and an increased incidence of aneuploidy in the Rae1 knockdown oocytes. Collectively, we propose that Rae1 modulates securin protein levels, which contribute to chromosome alignment, K-MT attachments, and aneuploidy in meiosis.

Checkpoint kinases are required for oocyte meiotic progression by the maintenance of normal spindle structure and chromosome condensation.

Checkpoint kinases (Chk) 1/2 are known for DNA damage checkpoint and cell cycle control in somatic cells. According to recent findings, the involvement of Chk1 in oocyte meiotic resumption and Chk2 is regarded as an essential regulator for progression at the post metaphase I stage (MI). In this study, AZD7762 (Chk1/2 inhibitor) and SB218078 (Chk1 inhibitor) were used to uncover the joint roles of Chk1/2 and differentiate the importance of Chk1 and Chk2 during oocyte meiotic maturation. Inhibition of Chk1/2 or Chk1 alone had no significant effect on germinal vesicle breakdown (GVBD) but significantly inhibited the first polar body (PB1). Interestingly, inhibition of Chk1 alone could not increase or completely block the extrusion of PB1 like Chk1/2 inhibition. Also, Chk1/2 inhibition resulted in defective meiotic spindle organization and chromosome condensation both in MI and metaphase II (MII) stages of oocytes. The location of γ-tubulin and Securin were abnormal or missing, while P38 MAPK was activated by Chk1/2 inhibition. Meanwhile, Chk1/2 inhibition reduced the percentage of the second polar body extrusion and pronuclear formation. In conclusion, our results further understand the functions and regulatory mechanism of Chk1/2 during oocyte meiotic maturation.

CoQ10 improves meiotic maturation of pig oocytes through enhancing mitochondrial function and suppressing oxidative stress.

Coenzyme Q10 (CoQ10) is essential to many fundamental biological processes. However, the effect of CoQ10 on meiotic maturation of pig oocytes still remains elusive. In the present study we aimed to understand the effects of CoQ10 on porcine oocyte maturation, by supplementing different concentrations of CoQ10 (25, 50 and 100 µM) into the maturation medium. We showed that CoQ10 at 50 µM had better capacity to promote the nuclear maturation of pig oocytes derived from both small and large antral follicles. Though the cleavage and blastocyst rates of parthenotes stayed stable, 50 µM CoQ10 treatment could accelerate the development of parthenotes to blastocyst stage, and increase the average cell number of blastocyst. For cumulus-oocyte complexes from large antral follicles categorized by the brilliant cresyl blue (BCB) test, 50 µM CoQ10 treatment could specifically promote the nuclear maturation of poor-quality oocytes in the BCB-negative group. Mitochondrial function of oocytes treated by 50 µM CoQ10 could be boosted, through increasing the levels of mitochondrial membrane potential, ATP production and CoQ6, and changing the pattern of mitochondrial distribution as well. Moreover, 50 µM CoQ10 treatment suppressed the level of reactive oxygen species and reduced the percentage of oocytes with early apoptosis signal. Taken together, CoQ10 could improve the meiotic maturation of pig oocytes, especially for poor-quality oocytes, mainly through enhancing mitochondrial function and suppressing oxidative stress to reduce apoptosis.

CHIR99021 and rpIL6 promote porcine parthenogenetic embryo development and blastocyst quality.

Signaling pathways and transcription factors are involved in porcine embryonic development. Here, we demonstrate that glycogen synthase kinase-3 (GSK3) inhibitor, CHIR99021 and recombinant porcine interleukin-6 (rpIL6) significantly promote porcine parthenogenetic blastocyst formation (49.23 ± 8.40% vs 32.34 ± 4.15%), with increased inner cell mass (ICM) cell numbers (7.72 ± 2.30 vs 4.28 ± 1.60) and higher expression of pluripotent genes, such as OCT4, SOX2 and NANOG. Furthermore, CHIR99021 and rpIL6 improve blastocyst quality with increased blastocyst hatching percentage (16.19 ± 1.96% vs 10.25 ± 1.12%) and subsequently porcine pluripotent stem cells (pPSCs) derivation efficiency. These results advance the understanding of porcine pre-implantation development and provide evidences in improving the blastocyst quality.

Triclocarban exposure affects mouse oocyte in vitro maturation through inducing mitochondrial dysfunction and oxidative stress.

Triclocarban (TCC), a broad-spectrum lipophilic antibacterial agent, is the main ingredient of personal and health care products. Nonetheless, its ubiquitous presence in the environment has been established to negatively affect the reproduction in humans and animals. In this work, we studied the possible toxic effects of TCC on mouse oocytes maturation in vitro. Our findings revealed that TCC-treated immature mouse oocytes had a significantly reduced rate of polar body extrusion (PBE) compared to that of control. Further study demonstrated that the cell cycle progression and cytoskeletal dynamics were disrupted after TCC exposure, which resulted in the continuous activation of spindle assembly checkpoint (SAC). Moreover, TCC-treated oocytes had mitochondrial damage, reduced ATP content, and decreased mitochondrial membrane potential (MMP). Furthermore, TCC exposure induced oxidative stress and subsequently triggered early apoptosis in mouse oocytes. Besides, the levels of histone methylation were also affected, as indicated by increased H3K27me2 and H3K27me3 levels. In summary, our results revealed that TCC exposure disrupted mouse oocytes maturation through affecting cell cycle progression, cytoskeletal dynamics, oxidative stress, early apoptosis, mitochondria function, and histone modifications in vitro.