Epigenetic and non-epigenetic mode of SIRT1 action during oocyte meiosis progression

Background: SIRT1 histone deacetylase acts on many epigenetic and non-epigenetic targets. It is thought that SIRT1 is involved in oocyte maturation; therefore, the importance of the ooplasmic SIRT1 pool for the further fate of mature oocytes has been strongly suggested. We hypothesised that SIRT1 plays the role of a signalling molecule in mature oocytes through selected epigenetic and non-epigenetic regulation.Results: We observed SIRT1 re-localisation in mature oocytes and its association with spindle microtubules.In mature oocytes, SIRT1 distribution shows a spindle-like pattern, and spindle-specific SIRT1 action decreasesα-tubulin acetylation. Based on the observation of the histone code in immature and mature oocytes, we suggest that SIRT1 is mostly predestined for an epigenetic mode of action in the germinal vesicles(GVs) of immature oocytes. Accordingly, BML-278-driven trimethylation of lysine K9 in histone H3 in mature oocytes is considered to be a result of GV epigenetic transformation.Conclusions: Taken together, our observations point out the dual spatiotemporal SIRT1 action in oocytes,which can be readily switched from the epigenetic to non-epigenetic mode of action depending on the progress of meiosis.     

Role of microfilaments and microtubules in the invasion of EPC cells by Aeromonas hydrophila

The influence of the cytoskeleton on the invasion of Aeromonas hydrophila strain AhJ-1, isolated from diseased fish, in the monolayer cell of epithelioma papillosum cells of carp (EPC) was evaluated by the recovery of gentamicin-resistant bacteria from Triton X-100 cell lysates. The depolymerization of microfilaments (MF) by cytochalasin B and D inhibited the uptake of A. hydrophila in a dose-dependent manner and that of microtubules (MT) by colchicines and nocodazole did not affect the invasion of A. hydrophila in EPC cells significantly. The invasion frequency decreased approximately 62% with the addition of 0.1 microg/ml cytochalasin D and nearly 86% by the addition of 5.0 microg/ml. Invasion decreased approximately 49% and 83% by addition of cytochalasin B in a concentration of 2.5 microg/ml and 10.0 microg/ml. Colchicine and nocodazole, inhibitors of MT formation appears to have little effect on the invasion of EPC cells by strain Ah J-1. Thus MF formation, but not MT formation seems to play an important role in the internalization of A. hydrophila J-1.     

荧光定量PCR检测小鼠卵母细胞中Mad2 mRNA的表达

目的:应用SYBR G reen I染料法建立检测Mad2 mRNA表达的实时荧光定量PCR的方法,并探讨小鼠卵母细胞减数分裂成熟中Mad2 mRNA的表达。方法:采用实时荧光定量PCR的方法,以SYBR G reen I为荧光染料,梯度稀释的重组质粒为模板制作标准曲线,并以此方法分析了小鼠卵母细胞减数分裂成熟过程中Mad2 mRNA表达的动态变化。结果:建立了实时荧光定量检测方法分析小鼠卵母细胞中Mad2 mRNA的表达,该方法灵敏、特异,扩增效率接近100%。进行了标准曲线的制作,以及对目的基因Mad2转录水平的绝对定量。结论:实时荧光定量PCR是检测基因表达水平的理想选择,在小鼠卵母细胞减数分裂成熟过程中Mad2 mRNA表达存在动态变化。     

The regulation of calcium/calmodulin-dependent protein kinase II during oocyte activation in the rat

Increases in intracellular Ca2+ are required for oocyte activation and subsequent development. Calmodulin-dependent protein kinase II (CaMKII) plays a crucial role in oocyte activation. However, how CaMKII is regulated during this process is not well characterized. We show here for the first time in rat oocytes that CaMKII is phosphorylated during oocyte activation. CaMKII phosphorylation was suppressed by KN93, a CaMKII inhibitor, but not KN92, which is the inactive analogue of KN93. Electrical stimulation of rat oocytes resulted in degradation of both cyclin B and Mos, presumably due a rise in Ca2+ induced by the electrical pulse. KN93 blocked the degradation of both proteins induced by the electrical pulse. Addition of a protein phosphatase inhibitor, okadaic acid (OA), further increased the amount of CaMKII and also increased the amount of phosphorylated enzyme. Importantly, in oocytes undergoing spontaneous activation, accumulation and phosphorylation of CaMKII also occurs in a time-dependent manner. Consistent with this, addition of KN93 inhibited spontaneous activation. Collectively, our results show that CaMKII is phosphorylated during oocyte activation and that this phosphorylation is involved in inactivation of p34cdc2 kinase and somewhat involved in degradation of Mos. Furthermore, CaMKII phosphorylation is negatively regulated by a protein phosphatase.     

Effect of aspiration pressure during oocyte harvesting on oocyte recovery and in vitro development of ovine oocytes.

Oocytes from abattoir-sourced ovine ovaries were aspirated from 2- to 4-mm follicles using 25, 50 or 100 mmHg pressure and an aspiration pump, or a needle (20-G) and syringe (2.5 ml) and subjected to in vitro maturation, fertilization and culture to determine the effect of aspiration pressure on the number and quality of oocytes recovered, and early embryonic development. Oocyte recovery rate was similar between groups (range: 57.1-73.1%; p > 0.05). The number and percentage of grade I and II oocytes recovered was reduced for 100 mm (24.5 +/- 3.6 and 31.1 +/- 6.1%) compared with 25 mm (51.4 +/- 7.0 and 60.2 +/- 7.8%) and 50 mm pressure (40.8 +/- 5.6 and 50.3 +/- 4.4%) and a syringe (40.3 +/- 12.0 and 45.2 +/- 2.1%; p < 0.05). Oocyte cleavage was similar for all groups at 24 (range: 30.9-49.6%) and 48 h post-insemination (49.7-65.5%), but blastocyst formation (% cleaved oocytes) was lower for oocytes aspirated with 25 mm (37.8%) than 50 (69.2%) or 100 mm (67.2%) pressure, and a syringe (72.0%; p < 0.05). Embryo production efficiency (% of oocytes cultured developing to the blastocyst stage) was higher for oocytes aspirated with 50 mm (45.4%) and 100 mm pressure (43.8%) and a syringe (45.0%) than 25 mm pressure (18.8%; p < 0.05). These results demonstrate that the aspiration of ovine oocytes with an aspiration pressure of 50 mm, or aspiration with a needle and syringe are equally efficacious for the in vitro production of embryos.     

Dynamic changes in histone acetylation during sheep oocyte maturation

The changes in histone acetylation are not always consistent in various cell types and at different developmental stages. We immunostained specific antibodies against acetylated lysine 9 of histone H3 and acetylated lysines 5 and 12 of histone H4 in an effort to understand the detailed changes in histone acetylation during sheep oocyte meiosis. We found that the acetylation fluorescence signals of H3/K9 and H4/K12 on chromatin appeared intensively in the germinal vesicle (GV), late-GV (L-GV), and germinal vesicle breakdown (GVBD) stages and became weak in metaphase I (MI); however staining reappeared in anaphase I-telophase-I (AI-TI) and metaphase II (MII). Furthermore, staining was detected in the first polar bodies. The fluorescence signals of H4/K5 first appeared in the MI stage and became intensive in the AI-TI stage; however they were barely detectable in MII stage chromosomes and first polar bodies. We conclude that the acetylation patterns of H3/K9 and H4/K12 during oocyte meiotic maturation are similar and that the pattern of H4/K5 is unique.     

Alterations of concentrations of calcium and arachidonic acid and agglutinations of microfilaments in host cells during Toxoplasma gondii invasion

Toxoplasma gondii (T. gondii) invasion of host cells is a complicated process of interaction between parasites and host cells. In the present study we investigated the alterations of free Ca(2+) concentration ([Ca(2+)](i)) and cytoskeletons in phagocytic and non-phagocytic host cells and arachidonic acid (AA) concentration in cells supernatant during T. gondii invasion. T. gondii invasion induced significant elevation of intracellular [Ca(2+)](i) in phagocytic cells (J774A.1) but not in non-phagocytic cells (L929). Pre-treatment of J774A.1 cells with Phospholipase C (PLC) inhibitor (U73122), or Ca(2+) chelators (EGTA, BAPTA/AM) did not block elevations of [Ca(2+)](i) but the elevations were lower and of shorter duration than that in untreated cells. Pre-treatment of tachyzoites with Phospholipases A (PLA) inhibitors (4-BPB and AACOCF3) resulted in a similar pattern of increasing of [Ca(2+)](i) as that in Ca(2+) chelators treated cells. Agglutinations of microfilaments were observed in J774A.1 cells but not in L929 cells. No changes of microtubules were observed in either cell. Treatment of cells with cytoskeleton inhibitors (colchicines, cytochalasin-D) resulted in reduced cell infection ratios. AA concentration in J774A.1 cells supernatant reached 8.44-fold of basal concentration after T. gondii infection and those in 4-BPB or AACOCF3 pre-treated cells reached 7.70-fold and 8.09-fold of basal concentration, respectively. However, elevation of AA concentrations induced by 4-BPB or AACOCF3 treated tachyzoites were 3.02-fold and 2.65-fold of basal AA concentration. AA concentration in L929 cells supernatant reached 5.02-fold of basal concentration after T. gondii infection and those in 4-BPB or AACOCF3 pre-treated cells reached 4.75-fold and 4.78-fold of basal concentration, respectively. However, elevation of AA concentrations induced by 4-BPB or AACOCF3 treated tachyzoites were 2.06-fold and 2.43-fold of basal AA concentration. Results indicated that elevations of [Ca(2+)](i) and AA induced by T. gondii invasion were from both host cells and parasites. T. gondii invasion activated host cell PLC and triggered the PLC-PKC signal pathway, which resulted in the flowing of extracellular Ca(2+) and the releasing of intracellular Ca(2+) pool. Elevated [Ca(2+)](i) induced reorganization of host cell microfilaments. The invasion also activated secretory PLA(2) (sPLA(2)) and cytosolic PLA(2) (cPLA(2)) of the parasite to release AA, which increased the permeability of cell membrane.     

M细胞及其在病原入侵中的作用研究进展

M细胞又称微皱褶细胞(microfold cell)或膜性细胞(membranous cell),是组成黏膜免疫屏障的一类重要上皮细胞,在黏膜免疫和病原入侵方面发挥重要功能。论文就M细胞的形态、功能及其在病原入侵中的作用进行综述,以期拓展对M细胞的认识以及引起兽医领域对M细胞研究的关注。     

Study on the mechanism of maternal imprinting during oocyte growth

In mammals, both parental genomes are essential for normal ontogeny because epigenetic modifications imposed in the parents' gametes lead to parent-of-origin specific gene expression in their offspring. These phenomena are referred to as genomic imprinting. It has been shown that maternal imprinting is established during oocyte growth, lack of maternal imprinting in zygotes leads to early embryonic death, and in vitro system that allows establishment of maternal imprinting is developed. In this review, I describe the history of the discovery of genomic imprinting, the regulatory mechanisms of mammalian development by maternal imprinting, and the molecular mechanisms of genomic imprinting.     

Distribution and viability of spermatozoa in the canine female genital tract during post-ovulatory oocyte maturation

Background

Unlike other domestic mammals, in which metaphase-II oocytes are ovulated, canine ovulation is characterized by the release of primary oocytes, which may take 12 to up to 36 hours. Further 60 hours are needed for maturation to secondary oocytes which then remain fertile for about 48 hours. Oestrus takes 7 to 10 days on average and may start as early as a week before ovulation. This together with the prolonged process of post-ovulatory oocyte maturation requires an according longevity of spermatozoa in the female genital tract in order to provide a population of fertile sperm when oocytes have matured to fertilizability. Therefore the distribution and viability of spermatozoa in the bitch genital tract was examined during post-ovulatory oocyte maturation.

Methods

Thirteen beagle bitches were inseminated on the day of sonographically verified ovulation with pooled semen of two beagle dogs containing one billion progressively motile spermatozoa. Ovariohysterectomy was performed two days later (group 1, n = 6) and four days later (group 2, n = 7). The oviduct and uterine horn of one side were flushed separately and the flushing’s were checked for the presence of gametes. The oviducts including the utero-tubal junction and the uterine horns, both the flushed and unflushed, were histologically examined for sperm distribution.

Results

The total number of spermatozoa recovered by flushing was low and evaluation of viability was limited. Prophase-I oocytes were collected from oviduct flushing in group 1, whereas unfertilized metaphase-II oocytes were detected in group 2. From day 2 to day 4 after ovulation a significant decrease in the percentage of glands containing sperm (P<0.05) and a marked reduction of the mean sperm number in uterine horn glands were observed. A concomitant diminution of spermatozoa was indicated in the utero-tubal junction accompanied by a slight increase in sperm numbers in the mid oviduct.

Conclusions

Oocyte maturation to metaphase-II stage is accompanied by a continuous sperm detachment and elimination in the uterine horns. Entrance of spermatozoa into the caudal oviduct seems to be steadily controlled by the utero-tubal junction thus providing a selected sperm population to be shifted towards the site of fertilization when oocyte maturation is completed.     

Crocin supplementation during oocyte maturation enhances antioxidant defence and subsequent cleavage rate

The purpose of the present study was to assess the effect of crocin supplementation during oocyte maturation on the antioxidant defence and anti‐apoptotic ability and subsequent developmental competence of porcine oocytes. Oocytes were cultured in media containing 0, 300, 400 or 500 µg/ml of crocin. Upon maturation, the maturation rates, reactive oxygen species (ROS) and glutathione (GSH) levels, mRNA expression of genes (SOD, CAT, GPx, Bcl‐2, BAX and Caspase3), expression of cleaved caspase3 and subsequent embryo cleavage rates were measured. Results indicated that the maturation rate of the 400 µg/ml group was 86.80% (p < 0.01). The ROS concentration of the 500 µg/ml group was the lowest (p < 0.01). The GSH concentration of the 400 µg/ml group was the highest (p < 0.01). The SOD, CAT and GPx mRNA expression levels were the highest in the 300, 400 and 500 µg/ml groups, respectively, with the expression levels of all genes being significantly higher than that of the control group (p < 0.01). The Bcl‐2/BAX mRNA expression ratio in 400 and 500 µg/ml groups significantly higher than other groups and significantly decreased caspase3 expression level (p < 0.01). The expression level of cleaved caspase3 in the 500 µg/ml treatment group was the lowest, significantly lower than that of the control group (p < 0.01). The cleavage rate of the 400 µg/ml group was 62.50% (p < 0.01). These experimental results show that the supplementation of in vitro culture medium with 400 µg/ml of crocin significantly enhanced the antioxidant defence and anti‐apoptotic ability and subsequent cleavage rate of porcine embryo.     

Role of the hyaluronan receptor CD44 during porcine oocyte maturation

Previous our studies have shown that CD44, the principal receptor for hyaluronan, is present on cumulus cells during oocyte maturation. Although hyaluronan-CD44 interaction has been implicated in cumulus expansion and/or oocyte maturation, the full significance of CD44 remains unknown. The objective of the present study was to further investigate the role of CD44 in cumulus expansion and oocyte maturation in pigs. We demonstrate here in that CD44 has a key role in oocyte maturation but not in cumulus expansion. Previous studies have reported the physiological significance of cumulus expansion in oocyte maturation. However, our results suggest that cumulus expansion is a necessary condition for oocyte maturation, but that it is not sufficient on its own. Furthermore, western blot analysis demonstrated that the CD44 of the in vitro-matured cumulus-oocyte complexes (COCs) had a larger molecular weight and more terminal sialic acid, which has been proven to inhibit the hyaluronan-binding ability of the receptor, than the CD44 of the in vivo-matured COCs, indicating that the hyaluronan-CD44 interactions during in vitro maturation might be insufficient compared with those in vivo. The insufficient interactions of hyaluronan-CD44 during in vitro maturation may cause the inferior capacity of fertilization and development of oocytes matured in vitro.     

兔卵母细胞成熟过程中组蛋白H3Ser10磷酸化表达分析

为研究卵母细胞成熟过程中组蛋白H3第10位丝氨酸(H3Ser10)磷酸化变化规律及其表达水平,本研究以体外成熟免卵母细胞为材料,采用免疫荧光标记方法检测兔卵母细胞成熟各时期组蛋白H3Ser10磷酸化的动态分布,同时探讨不同浓度组蛋白磷酸化激酶抑制剂(ZM447439)处理卵母细胞对组蛋白H3Ser10磷酸化表达的影响.结果显示:(1)兔卵母细胞组蛋白H3Ser10磷酸化始于生发泡破裂期(GVBD),且表达水平最高;第1次减数分裂中期(MⅠ期)磷酸化水平降低,第1次减数分裂后期(AⅠ期)及第2次减数分裂中期(MⅡ期)磷酸化水平呈上升趋势,但均比GVBD期低.(2)低浓度ZM447439对兔卵母细胞核成熟进程影响不大,当其浓度增加到30 μmol/L时,93.5％的卵母细胞停留在GVBD期.(3)ZM447439浓度为5μmol/L时,20.7％卵母细胞H3Ser10去磷酸化,其他卵母细胞H3Ser10磷酸化信号与未处理组相似;当ZM447439浓度增加到30μmol/L时,大多数卵母细胞中的H3Ser10磷酸化消失.以上结果表明:兔卵母细胞组蛋白H3Ser10磷酸化始于GVBD期,且一直持续到MⅡ期,GVBD期磷酸化水平最高.ZM447439可有效抑制兔卵母细胞减数分裂的恢复,且随其浓度的增加,组蛋白H3Ser10磷酸化水平降低;当浓度达30μmol/L时,卵母细胞组蛋白H3Ser10终止磷酸化.     

Steroidogenesis and the influence of MAPK activity during in vitro maturation of porcine cumulus oocyte complexes

The aim of this study was to investigate steroidogenesis within porcine cumulus oocyte complexes during in vitro maturation and to examine the possible influence of the mitogen-activated protein kinase (MAPK). Porcine cumulus oocyte complexes were matured in vitro with and without the MAPK kinase inhibitor U0126 for 0, 5, 26 and 46 h. The 17β-estradiol and progesterone concentration in the culture medium were then determined. In addition, the mRNA levels of StAR, Cyp11A1, 3β-HSD and Cyp19A1 in cumulus cells were analysed by RT-PCR. Using an immunoblot, the MAPK phosphorylation in cumulus cells and oocytes was examined. During the first 26 h of in vitro maturation, 17β-estradiol secretion was predominant, whereas, after a culture period of 46 h, the progesterone secretion decreased conspicuously. Under the influence of U0126, the secretion of 17β-estradiol increased progressively during the complete maturation period, while progesterone secretion was completely inhibited. The mRNA levels of StAR and Cyp11A1 were not altered by U0126; however, corresponding to the hormone secretion, the gene expression of Cyp19A1 was up-regulated and the expression of 3β-HSD down-regulated. The results suggested an influence of the MAPK on steroidogenesis in cumulus cells comparable to a luteinization factor. Hormone synthesis in cumulus cells during oocyte maturation seems to be regulated by altering expression of Cyp19A1 and 3β-HSD.     

Effect of time of oocyte collection and site of insemination on oocyte transfer in mares

The objective of the study was to compare embryo development rates after transfer of oocytes collected 22 or 33 h after hCG injection into recipients inseminated within the uterus or the oviduct. Oocytes were collected at approximately 22 or 33 h after hCG injections and incubated for approximately 16 or 1.5 h, respectively, before transfer. Intrauterine inseminations using 1 x 10(9) progressively motile sperm were done approximately 12 h before and 2 h after transfer. For intraoviductal inseminations (gamete intrafallopian transfer [GIFT]), semen was centrifuged through a Percoll gradient, and 200,000 progressively motile sperm were transferred with oocytes into the oviduct. Time of oocyte collection (22 or 33 h) after hCG injection did not affect embryo development rates (17/25, 68%, vs 12/23, 52%, respectively; P = 0.40). When results from oocyte collections at 22 and 33 h after hCG were combined, oocyte transfer with intraoviductal vs intrauterine insemination resulted in similar (P = 0.70) embryo development rates (12/22, 55%, and 17/26, 65%, respectively). However, the interaction between time of oocyte collection and site of insemination tended to be significant (P = 0.09), suggesting that GIFT using oocytes collected at 33 h after hCG may not be as effective as using oocytes collected at 22 h after hCG. Because intraoviductal insemination requires a low number of sperm, GIFT could be used in cases of male subfertility, frozen semen, or sexed sperm.     

Aurora A inhibition disrupts chromosome condensation and spindle assembly during the first embryonic division in pigs

As common overexpression of Aurora A in various tumours, much attention has focused on its function in inducing cancer, and its value in cancer therapeutics, considerably less is known regarding its role in the first cleavage division of mammalian embryos. Here, we highlight an indispensable role of Aurora A during the first mitotic division progression of pig embryos just after meiosis. The expression and spatiotemporal localization of Aurora A were initially assessed in pig embryos during the first mitotic division by Western blot analysis and indirect immunofluorescent staining. Then, the potential role of Aurora A was further evaluated using a highly selective Aurora A inhibitor, MLN8054, during this mitotic progression in pig embryos. Aurora A was found to express and exhibit a specific dynamic intracellular localization pattern during the first mitotic division in pig embryos. Aurora A was diffused in the cytoplasm at the prophase stage, and then exhibited a dynamic intracellular localization which was tightly associated with the chromosome and spindle dynamics throughout subsequent mitotic phases. Inhibition of Aurora A by MLN8054 treatment led to the failure of the first cleavage, with the majority of embryos being arrested in prophase of the mitotic division. Further subcellular structure examination showed that Aurora A inhibition not only led to the failure of spindle microtubule assembly, but also resulted in severe defects in chromosome condensation, accompanied by an obvious decrease in p-TACC3(S558) expression during the prophase of the first mitosis. Together, these results illustrated that Aurora A is crucial for both spindle assembly and chromosome condensation during the first mitotic division in pig embryos, and that the regulation of Aurora A may be associated with its effects on p-TACC3(S558) expression.     

波尔山羊卵母细胞和早期胚胎的端粒酶活性

利用端粒重复序列扩增（TRAP）法进行了山羊卵母细胞和附植前胚胎的端粒酶活性的测定;结果表明,山羊卵母细胞和早期胚胎的端粒酶活性都为阳性.TPG定量比较发现,卵母细胞的TPG最低,为25.348U;4-细胞的TPG为273.832U,至8一细胞时,TPG又降低到56.117U,随后快速升高,桑椹胚的TPG为251.111U;囊胚的端粒酶活性最高,TPG为519.46U.     

Role of actin microfilaments in canine distemper virus replication in vero cells

Several studies have indicated that viruses require a specific cytoskeletal structure for replication in host cells. In this study, we examined the role of actin fiber in the replication of canine distemper virus (CDV), belonging to the Morbillivirus genus of the family Paramyxoviridae. For this purpose, we used two actin depolymerizing agents, cytochalasin-D (C-D) and mycalolide-B (ML-B). In Vero cells, C-D disrupted actin fibers distributed in the cytosol, but peripheral actin fibers remained intact. On the other hand, ML-B completely disrupted the actin fibers distributed in both areas. Treatment of Vero cells with C-D or ML-B inhibited the replication of CDV. Double staining of CDV-infected Vero cells with antibody to N-protein and rhodamine-phalloidin revealed the presence of N-protein in mid-cytoplasm. However, the N-protein was specifically localized at the submembrane region in the presence of C-D, whereas it was clustered in the presence of ML-B. Viral mRNA levels of N- and H-proteins were rather increased by treatment with C-D or ML-B. The treatment with ML-B strongly inhibited N-protein expression, whereas C-D only slightly inhibited N-protein expression. These results suggest that actin microfilaments distributed in the cytoplasm and on the membrane region in host cells may have a different role in the process of CDV replication.     

DRP1 deficiency induces mitochondrial dysfunction and oxidative stress-mediated apoptosis during porcine oocyte maturation

Background: Environmental pollution induces oxidative stress and apoptosis in mammalian oocytes, which can cause defects in reproduction;however, the molecular regulation of oxidative stress in oocytes is still largely unknown. In the present study, we identified that dynamin-related protein 1(DRP1) is an important molecule regulating oocyte mitochondrial function and preventing oxidative stress/apoptosis. DRP1 is a member of the dynamin GTPase superfamily localized at the mitochondrial-endoplasmic reticulum interaction site, where it regulates the fission of mitochondria and other related cellular processes.Results: Our results show that DRP1 was stably expressed during different stages of porcine oocyte meiosis, and might have a potential relationship with mitochondria as it exhibited similar localization. Loss of DRP1 activity caused failed porcine oocyte maturation and cumulus cell expansion, as well as defects in polar body extrusion.Further analysis indicated that a DRP1 deficiency caused mitochondrial dysfunction and induced oxidative stress,which was confirmed by increased reactive oxygen species levels. Moreover, the incidence of early apoptosis increased as detected by positive Annexin-V signaling.Conclusions: Taken together, our results indicate that DRP1 is essential for porcine oocyte maturation and that a DRP1 deficiency could induce mitochondrial dysfunction, oxidative stress, and apoptosis.