Search Results (119)

Oocytes cultured in vitro are exposed to high oxygen tension and lack follicular antioxidants, leading to redox imbalance. Eicosapentaenoic acid (EPA), a marine long-chain n-3 polyunsaturated fatty acid, possesses strong antioxidant activity. Here, using pigs as a model, we examined the effects of EPA on oocyte in vitro maturation (IVM) and subsequent developmental competence. Cumulus–oocyte complexes were cultured with EPA, followed by assessment of nuclear and cytoplasmic maturation and embryonic development; transcriptomic and proteomic analyses were conducted to explore underlying mechanisms. Supplementation with 10 µM EPA significantly improved maturation and blastocyst rates by reducing spindle defects, facilitating a more uniform organization of cortical granules and mitochondria. EPA increased resolvin E1 accumulation and reduced cumulus-cell apoptosis through downregulation of TNF-α and BAX and upregulation of BCL2. In MII oocytes, EPA lowered apoptosis, DNA damage, and ROS levels while enhancing SOD2 and GPX4 expression. Mitochondrial quality and turnover were improved via upregulation of PPARGC1A, NDUFS2, PINK1, LC3, FIS1, MUL1, and OPA1, alongside strengthened ER–mitochondria contacts. These findings demonstrate that EPA alleviates oxidative stress, optimizes mitochondrial function, and enhances porcine oocyte maturation and developmental competence in a parthenogenetic model, highlighting its potential as a marine-derived functional additive for reproductive biotechnology. Future studies will be required to validate these effects under fertilization-based embryo production systems and to further refine dose–response relationships using expanded embryo-quality endpoints. Full article

Oocyte-granulosa cell complexes (OGCs) cultivation is crucial for advancing reproductive biotechnology but remains incomplete and needs further optimization. Insulin-like growth factor-I (IGF-I) regulates granulosa cell proliferation and apoptosis, and numerous studies have confirmed its role in promoting ovarian follicle development. Porcine follicular fluid (PFF) contains factors beneficial for oocyte growth, which may enhance oocyte development. To investigate whether IGF-I and PFF improve the in vitro culture efficiency of porcine OGCs, we cultured OGCs with IGF-I (0, 10, 50, 100 ng/mL) and PFF (from 3 to 6 mm follicles) at concentrations of 0, 2.5%, 5%, 10%, respectively. The results revealed that 50 and 100 ng/mL IGF-I significantly increased the antrum formation rate of OGCs (from 61.11 ± 7.35% to 88.89 ± 7.35%) and diameter growth of oocytes (from 108.77 ± 0.27 µm to 114.94 ± 0.58 and 113.29 ± 0.50 µm, respectively). However, only the 50 ng/mL group, but not the 100 ng/mL group, significantly improved the maturation rate (38.13 ± 3.77% vs. 25.00 ± 3.27%, p < 0.05) of oocytes. Additionally, 50 ng/mL IGF-I downregulated BAX (a pro-apoptotic gene) and upregulated BCL-2 (an anti-apoptotic factor) in granulosa cells, ultimately reducing apoptosis. In contrast, none of the PFF doses used in this study induced the formation of enclosed antrum-like structures in OGCs, nor did they significantly enhance their in vitro development. Our findings demonstrate that 50 ng/mL IGF-I effectively promotes the in vitro growth of porcine early antral follicle-derived OGCs by reducing apoptosis, whereas tested PFF concentrations had no beneficial effects and induced abnormal granulosa cell growth. How PFF modulates the adherent and spreading growth of granulosa cells has not been fully elucidated and requires further clarification. Full article

Early mammalian embryo development is a temporally regulated process initially governed by maternal factors during the first few cleavage divisions. In porcine embryos, the transition from oocyte to embryonic control occurs around the 4-cell stage. This developmental progression depends on embryonic genome activation (EGA), epigenetic reprogramming, metabolic cues, and extracellular signaling pathways. While fundamental aspects of early development are conserved across mammals, porcine embryos exhibit distinct molecular features, including unique EGA timing, altered regulatory gene expression, and a pronounced reliance on lipid metabolism. This review provides a comprehensive overview of recent advances in understanding the molecular mechanisms underlying early porcine embryo development, from fertilization to blastocyst formation. It summarizes molecular changes associated with the maternal regulation of initial embryonic divisions, genome activation, chromatin remodeling, and the role of transcription factors and metabolic pathways. Additionally, the review examines the impact of in vitro culture conditions on these molecular processes. A thorough understanding of these mechanisms is critical for optimizing embryo culture systems, improving developmental outcomes, and advancing agricultural biotechnology. Full article

The preservation of porcine oocytes is critically important for advancing superior breeds and conserving genetic resources in pig production. Vitrification has gained traction as a preferred alternative to slow freezing for porcine oocytes because of its effectiveness in reducing ice crystal formation, yet it can still negatively affect oocyte quality, compromising their in vitro maturation (IVM) and later embryonic development. Long non-coding RNAs (lncRNAs) have proven to be key players in numerous biological processes, such as oocyte growth, maturation, and early embryogenesis. Despite this, the effects of vitrified porcine germinal vesicle (GV) oocytes, particularly regarding IVM and the dynamic expression patterns of lncRNAs during embryonic development, remain largely unclear. To address this gap, this study conducted lncRNA sequencing at the metaphase II (MII), parthenogenetic 4-cell embryo, and parthenogenetic blastocyst stages sourced from both fresh and vitrified GV oocytes. This method enabled us to ascertain the impact of vitrification on lncRNA expression throughout oocyte maturation and embryonic development. Results identified 773 differentially expressed lncRNAs (DELs) at the MII stage, 1973 at the parthenogenetic 4-cell, and 1192 at the parthenogenetic blastocyst. Enrichment analysis of forecasted target genes revealed their involvement in key regulatory pathways associated with the cell cycle, meiosis, stress response, and metabolic activity. Overall, this study provides a comprehensive overview of lncRNA expression during oocyte maturation and embryonic development following porcine GV oocyte vitrification, thereby shedding light on the molecular mechanisms behind vitrification-induced damage. Full article

Since individual embryos cannot be evaluated in group culture, establishing a single culture from in vitro maturation to in vitro culture may provide new insights into oocyte and embryo quality. This study aimed to develop a single culture system for individual oocytes, from in vitro maturation through fertilization to embryo development. The effects of curcumin supplementation during in vitro maturation on oocyte maturation, embryo development, and embryo quality were examined in single and group culture systems. Porcine oocytes were cultured individually in 20 µL microdroplets, with one oocyte per droplet, or in groups of 50 oocytes per 500 µL. The maturation medium contained curcumin at concentrations of 20 µM or less. Supplementation with 10 µM curcumin increased oocyte maturation in both systems compared to the controls. The fertilization rates and oocyte/embryo quality did not differ among the treatment groups. Oocytes matured with 10 µM curcumin in a single culture showed a higher blastocyst formation rate (7.0%) than the control (2.3%). In the group culture, 10 µM curcumin increased cleavage rates compared to the control (75.2% vs. 63.0%), but blastocyst formation rates did not differ. Blastocyst formation rates were similar between single and group cultures under control (2.3% and 4.3%, respectively) or 10 µM curcumin (7.0% and 11.4%, respectively) conditions. Therefore, porcine oocytes can develop to the blastocyst stage in a single culture system. Incorporating antioxidants during in vitro maturation may be an effective condition for in vitro embryo culture that can be implemented in a single oocyte. Full article

Triclosan (TCS), a widely used environmental antimicrobial agent, poses potential risks to female reproductive health, yet its toxic effects on oocyte maturation remain inadequately characterized. In this study, we established an in vitro maturation (IVM) model of porcine oocytes to investigate TCS-induced meiotic impairment and to evaluate the rescuing effects of melatonin (MT), an endogenous indoleamine with potent antioxidant and anti-apoptotic activities. Our results demonstrated that TCS exposure significantly disrupted oocyte maturation, as evidenced by suppressed polar body extrusion and compromised cumulus expansion. Furthermore, TCS triggered early apoptosis. Proteomic analysis revealed that the p53 signaling pathway was significantly dysregulated by TCS exposure. Notably, co-treatment with MT during IVM effectively restored meiotic progression, attenuated apoptosis, and rebalanced the disrupted proteomic profile. Mechanistic investigation, validated by Western blotting, confirmed that TCS upregulated p53 and downregulated its downstream cell cycle effector CCNB1 while concurrently altering the ratio of apoptosis-related proteins BAX/BCL-2. Melatonin treatment effectively normalized the expression of these key proteins (p53, CCNB1, BAX, and BCL-2). These findings illustrate that MT rescues TCS-impaired oocyte quality through p53-dependent suppression of apoptosis and restoration of meiotic progression, providing new insights into potential strategies for mitigating environmental pollutant-induced reproductive damage. Full article

Polystyrene microplastics (PS-MPs) are microplastic particles produced during plastic manufacturing and environmental degradation, accumulating over time and entering ecosystems through various pathways, ultimately affecting organisms and inducing toxic effects. Current research on the impact of PS-MPs on mammalian oocyte quality, along with potential preventive mechanisms and strategies to mitigate toxicity, remains limited. This study investigates the effects of antioxidant melatonin on oocyte quality in the presence of PS-MPs, focusing on their influence on oocyte meiotic maturation and embryonic developmental potential. PS-MPs at a concentration of 30 μg/mL significantly impaired first polar body extrusion and reduced the success rate of parthenogenetic activation of mature oocytes in vitro. Furthermore, exposure to PS-MPs exacerbated oxidative stress, mitochondrial dysfunction, apoptosis, and autophagy impairment. Additionally, PS-MPs exposure led to a reduction in antioxidant gene expression and an increase in apoptosis-related gene expression in porcine oocytes. Immunofluorescence assays revealed that PS-MPs may induce oxidative stress, mitochondrial damage, and inflammation through the NF-KB/Nrf2/JNK MAPK signaling pathway crosstalk. Further investigation demonstrated that melatonin supplementation alleviated the toxic effects of PS-MPs exposure, offering potential as a therapeutic approach for mitigating PS-MP-induced reproductive toxicity and preserving oocyte quality. Full article

Acetamiprid (ACE), a widely used neonicotinoid insecticide, has raised concerns due to its potential reproductive toxicity. While its adverse effects on animal reproductive systems have been documented, the impact of ACE on mammalian oocytes remains poorly understood. This study aimed to investigate the potential effects of ACE exposure on porcine oocytes and evaluate whether alpha-tocopherol (α-TOC), a fat-soluble antioxidant, could alleviate ACE-induced oocyte damage. Porcine cumulus oocyte complexes (COCs) were exposed to ACE alone or co-treated with α-TOC for 44 h during in vitro maturation. ACE exposure significantly reduced the first polar body (PB1) excretion rate, arrested meiotic progression, and disrupted spindle assembly in porcine oocytes. Furthermore, ACE impaired mitochondrial function, evidenced by decreased mitochondrial membrane potential (MMP), while increasing intracellular reactive oxygen species (ROS) accumulation and lipid peroxidation (LPO). Additionally, ACE exposure induced intracellular iron overload and dysregulated ferroptosis-related genes, downregulating solute carrier family 7 member 11 (SLC7a11) and glutathione peroxidase 4 (GPX4) while upregulating transferrin receptor 1 (TfRC) and acyl-CoA synthetase long-chain family member 4 (ACSL4), contributing to the occurrence of oocyte ferroptosis. Notably, α-TOC co-treatment effectively alleviate oxidative stress and lipid peroxidation, thereby protecting oocytes from ACE-induced ferroptosis. Collectively, these findings indicate that oxidative stress-mediated ferroptosis may be a major contributing pathway through which ACE impairs oocyte maturation and suggest that α-tocopherol may serve as a protective agent against ACE-induced oocyte damage. Full article

C-type natriuretic peptide (CNP), encoded by the NPPC (Natriuretic Peptide Precursor C), has been recognized as the principal endogenous factor sustaining oocyte meiotic arrest in mammalian follicles. Yet its influence on porcine ovarian granulosa cell fate and the regulatory mechanism of NPPC expression within these cells remain poorly understood. Here, utilizing an in vitro culture model of primary porcine ovarian granulosa cells and immature oocytes, we examined the impact of CNP on granulosa cell apoptosis and oocyte meiotic resumption, and elucidated the molecular circuitry governing NPPC expression. We found that follicular atresia in pigs was accompanied by a marked decline in the CNP receptor NPR2 (natriuretic peptide receptor 2). Correspondingly, exogenous CNP suppressed apoptosis in cultured porcine granulosa cells. Estradiol can significantly promote the expression level of NPPC in porcine ovarian granulosa cells and, by enhancing NPR2 levels, it can synergize with CNP to inhibit oocyte meiotic resumption in vitro. Conversely, EGF signaling can significantly downregulate NPPC mRNA expression in porcine granulosa cells, an effect likely mediated by ERK-activated tristetraprolin (TTP). Collectively, these findings broaden our understanding of CNP in follicular development and delineate the endocrine network that controls NPPC transcription in the porcine ovary. Full article

This research explored the effects of different concentrations of p-coumaric acid (PCA) on the quality of frozen-thawed boar semen. Boar sperm samples were pre-treated with different concentrations of PCA (0, 30, 60, 90, 120 μg/mL) prior to the freezing process. Subsequently, multiple parameters were analyzed post-freeze-thawing, including sperm morphological and kinetic characteristics, acrosome and membrane integrity, mitochondrial function, DNA integrity, antioxidant enzyme activities, the expression levels of the BCL-2, BAX, and Caspase-3 proteins, the in vitro fertilization rate of porcine oocytes, and the embryo cleavage rate. The findings indicated that, compared with the control group, the addition of 90 μg/mL PCA led to significant improvements in several key aspects. Sperm motility, average path velocity, straight-line velocity, curvilinear velocity, and beat cross frequency were all notably enhanced. Moreover, parameters related to sperm quality, such as acrosome integrity, plasma membrane integrity, mitochondrial activity, and DNA integrity, also showed significant increases (all p < 0.05). In terms of antioxidant capacity, the 90 μg/mL PCA treatment significantly elevated the total antioxidant capacity, as well as the activities of superoxide dismutase, glutathione peroxidase, and catalase. Simultaneously, it caused a significant reduction in the contents of malondialdehyde and hydrogen peroxide (p < 0.05). Regarding protein expression, the addition of 90 μg/mL PCA significantly upregulated the expression level of the BCL-2 protein, while downregulating the relative expression levels of BAX and Caspase-3 (p < 0.05). Additionally, this concentration of PCA significantly improved the in vitro fertilization rate of porcine oocytes and the embryo cleavage rate (p < 0.05). In conclusion, incorporating PCA into the semen extender can potentially be advantageous for the cryopreservation of boar sperm, with 90 μg/mL being the optimal concentration. Full article

This study investigated the effects of high (atmospheric) and low (5% O₂) oxygen tension, as well as a combination of the two, on oocyte metabolism and quality during maturation. Cumulus cell–oocyte complexes collected from gilt ovaries were used for in vitro maturation. In addition, RNA-seq was conducted on the cumulus cells. Low oxygen tension throughout oocyte maturation did not alter the developmental rate to the blastocyst stage; however, it increased oocyte ATP and lipid content while reducing mitochondrial reactive oxygen species and mitochondrial membrane potential. Low-oxygen conditions increased glucose consumption but reduced mitochondrial DNA copy number and mitochondrial protein in cumulus cells. RNA-seq of cumulus cells revealed that low oxygen tension reduced mitochondrial activity and increased glycolysis, with the upregulation of glycolytic genes and downregulation of oxidative phosphorylation and steroidogenesis-related genes. In addition, a two-step oxygen protocol with low (5%) for the first period (0–21 h) and high (20%) for the last half period (21–44 h) increased the ATP and lipid content in oocytes and improved the embryonic developmental ability of the oocytes compared to the high-oxygen group. In conclusion, low oxygen tension during the first part of the maturation period is beneficial for oocyte quality, considering the observed metabolic changes. Full article

Long non-coding RNAs (lncRNAs) are essential regulatory molecules involved in various biological processes in mammals. However, their expression patterns across multiple porcine tissues have not been systematically characterized. We analyzed 607 RNA-seq datasets derived from 14 porcine tissues, including backfat, gallbladder, heart, ileum, jejunum, kidney, longissimus dorsi, liver, lung, skeletal muscle, ovary, pituitary, skeletal muscle, and spleen. Additionally, we examined 63 single-cell RNA-seq datasets from porcine primary oocytes at five developmental stages. For comparative analysis, we included 20 human and 17 mouse oocyte RNA-seq datasets. We identified 52,798 porcine lncRNAs, with tissue-specific expression patterns most prominent in oocytes and least in skeletal muscle. Among them, 2169 were classified as housekeeping and 14,469 as tissue-specific lncRNAs. Cross-species analysis revealed that a small subset of oocyte-expressed lncRNAs is conserved in humans and mice, associated with catalytic activity and circadian regulation. Additionally, 44 lncRNAs were differentially expressed during oocyte development, implicating them in neurogenesis, vesicle transport, and protein modification. Our findings not only contribute to the growing body of knowledge regarding lncRNAs in porcine biology but also pave the way for future research aimed at elucidating their functional roles in reproductive biology and other physiological processes. Full article

Mechanical models are capable of simulating the deformation and stress distribution of oocytes under external forces, thereby providing insights into the underlying mechanisms of intracellular mechanical responses. Interactions with micromanipulation tools involve forces like compression and punction, which are effectively analyzed using principles of solid mechanics. Alternatively, fluid–structure interactions, such as shear stress at fluid junctions or pressure gradients within microchannels, are best described by a multiphase flow model. Developing the two models instead of a single comprehensive model is necessary due to the distinct nature of cell–tool interactions and cell–fluid interactions. In this study, we developed a finite element (FE) model of porcine oocytes that accounts for the viscoelastic properties of the zona pellucida (ZP) and cytoplasm for the case when the oocytes interacted with a micromanipulation tool. Atomic force microscopy (AFM) was employed to measure the Young’s modulus and creep behavior of these subcellular components that were incorporated into the FE model. When the oocyte was solely interacting with the fluids, we simulated oocyte deformation in microfluidic channels by modeling the oocyte-culture-medium system as a three-phase flow, considering the non-Newtonian behavior of the oocyte’s components. Our results show that the Young’s modulus of the ZP and cytoplasm were determined to be 7 kPa and 1.55 kPa, respectively, highlighting the differences in the mechanical properties between these subcomponents. Using the developed layered FE model, we accurately simulated oocyte deformation during their passage through a narrow-necked micropipette, with a deformation error of approximately 5.2% compared to experimental results. Using the three-phase flow model, we effectively simulated oocyte deformation in microfluidic channels under various pressures, validating the model’s efficacy through close agreement with experimental observations. This work significantly contributes to assessing oocyte quality and serves as a valuable tool for advancing cell mechanics studies. Full article

Mitochondrial-targeted antioxidant supplementation is promising for in vitro culture of mammalian embryos. Elamipretide (SS-31) is a synthetic tetrapeptide that binds to the inner mitochondrial membrane, contributing to the prevention of oxidative stress. In this study, the effects of SS-31 supplementation in maturation medium on the developmental competence of porcine oocytes and its protective function were evaluated. Porcine oocytes were matured in maturation medium with SS-31 at 0.001, 0.01, 0.1, 0.5, 1, 1.5, 2.5, and 5 µM, with 0 µM and DMSO-treated groups established as controls. In vitro fertilization and embryo culture were performed to analyze developmental potential. Oocytes cultured in medium with 1 µM SS-31 exhibited higher maturation and blastocyst formation rates than the control (0 µM) (78.3 ± 3.8% vs. 55.2 ± 4.1% and 7.6 ± 1.6% vs. 2.8 ± 1.8%, respectively). Oocytes treated with 1 µM SS-31 showed significantly lower reactive oxygen species, higher glutathione content, and improved mitochondrial membrane potential than those without treatment. DNA fragmentation in oocytes after in vitro maturation was significantly lower in the 1 µM SS-31 supplemented group than in the control. This study demonstrates that SS-31 exerts beneficial effects on the in vitro production of porcine embryos via the enhancement of the mitochondrial antioxidant capacity. Full article

To achieve the goals of productivity and sustainability across diverse livestock systems, reproductive factors play a pivotal role. Historically, reproductive research has primarily focused on females, as they are responsible for maintaining pregnancy and delivering offspring following oocyte fertilization. However, since the early 2000s, the biological significance of sperm RNAs has been increasingly recognized in various livestock species. These RNAs contribute both genetically and epigenetically at the time of fertilization and during early embryonic development. Multiple types of sperm RNA have been identified in bovine, porcine, ovine, buffalo, and caprine spermatozoa. Notably, transcriptomic profiling has shown potential to differentiate between high- and low-fertility males, even when conventional semen quality values appear normal in both groups. This opens the possibility for more accurate identification of highly fertile sires. Nevertheless, a definitive marker or set of markers has yet to be established, likely due to the transcriptome’s sensitivity to environmental conditions and to the variability in evaluation methodologies. Therefore, global scientific efforts should aim to establish standardized, robust protocols, as sperm RNA represents a promising avenue for enhancing the sustainability of animal production systems. Full article