Background: Despite considerable technological advancements, polyspermy remains a significant challenge in in vitro fertilization (IVF) procedures in pigs, disrupting normal embryonic development. Here, we aimed to determine whether optimal fertilization conditions reduce the polyspermy incidence in pigs. Methods: In vitro -matured oocytes were co-incubated with sperm according to a modified two-step culture system. Results: In the first experiment, oocytes were briefly co-incubated with sperm, washed in IVF medium, and then moved to fresh IVF medium for 5 or 6 h. Although the 6 h sperm-free cultured group had a higher penetration rate than the 5 h cultured group, the polyspermy rate significantly increased in the 6 h sperm-free cultured group. The gamete co-incubation period was either 20 or 40 min. The 40 min cultured group had a higher rate of blastocyst formation and number of total cells in blastocysts than the 20 min cultured group. In experiment 2, oocytes were inseminated with sperm separated by Pecroll treatment. Percoll treatment increased the rate of oocyte penetration and blastocyst formation compared to the control. In experiment 3, fertilized oocytes were cultured in 25 μL microdroplets (10 gametes/drop) or 500 μL (100 gametes/well) of culture medium in 4-well plates. The large volume of medium significantly reduced the number of dead oocytes and increased the rate of blastocyst formation compared to the small volume. Conclusions: Collectively, these results demonstrate that various fertilization conditions, including modified co-culture period, active sperm separation, and culture medium volume, enhance fertilization efficiency and subsequent embryonic development by decreasing polyspermy occurrence.

Alpha-linolenic acid is an important polyunsaturated fatty acid that exhibits anticancer, anti-inflammatory, and antioxidative effects. In this study, we investigated the protective effects of alpha-linolenic acid on the cell proliferation and differentiation of C2C12 cells under essential amino acid-deficient conditions. Different concentrations of alpha-linolenic acid and essential amino acids were added to the growth and differentiation media. The concentrations of 10 μM of alphalinolenic acid and 2% essential amino acid were chosen for subsequent experiments. Supplementation with alpha-linolenic acid and essential amino acids improved the proliferation and differentiation of C2C12 cells and significantly increased the mRNA levels of catalase, superoxide dismutase, B-cell lymphoma-2, and beclin-1 as well as the protein levels of PPARγ coactivator-1α compared to those in the controls. Moreover, supplementation with alpha-linolenic acid and essential amino acids reduced the levels of phosphorylated H2A.X variant histone, Bcl-2-associated X, p53, and light chain 3 during C2C12 cell proliferation, and increased the expression levels of myogenic factors 4 (myogenin) and 5 during C2C12 cell differentiation. Overall, we determined that alpha-linolenic acid and essential amino acids maintained the cell proliferation and differentiation of C2C12 cells via their anti-oxidative, anti-apoptotic, and anti-autophagic effects.

Nitric oxide (NO)-induced protein S-nitrosylation triggers mitochondrial dysfunction and was related to cell senescence. However, the exact mechanism of these damages is not clear. In the present study, to investigate the relationship between in vitro aging and NO-induced protein S-nitrosylation, oocytes were treated with sodium nitroprusside dihydrate (SNP), and the resultant S-nitrosylated proteins were detected through biotin-switch assay. The results showed that levels of protein S-nitroso thiols (SNO)s and expression of S-nitrosoglutathione reductase (GSNOR) increased, while activity and function of mitochondria were impaired during oocyte aging. Addition of SNP, a NO donor, to the oocyte culture led to accelerated oocyte aging, increased mitochondrial dysfunction and damage, apoptosis, ATP deficiency, and enhanced ROS production. These results suggested that the increased NO signal during oocyte aging in vitro, accelerated oocyte degradation due to increased protein S-nitrosylation, and ROS-related redox signaling.

Cell adhesion plays an important role in the differentiation of the morphogenesis and the trophectoderm epithelium of the blastocyst. In the porcine embryo, CDH1 mediated adhesion initiates at compaction before blastocyst formation, regulated post-translationally via protein kinase C and other signaling molecules. Here we focus on muscle RAS oncogene homolog (M-RAS), which is the closest relative to the RAS related proteins and shares most regulatory and effector interactions. To characterize the effects of M-RAS on embryo compaction, we used gain- and loss-of-function strategies in porcine embryos, in which M-RAS gene structure and protein sequence are conserved. We showed that knockdown of M-RAS in zygotes reduced embryo development abilities and CDH1 expression. Moreover, the phosphorylation of ERK was also decreased in M-RAS KD embryos. Overexpression of M-RAS allows M-RAS KD embryos to rescue the embryo compaction and blastocyst formation. Collectively, these results highlight novel conserved and multiple effects of M-RAS during porcine embryo development.

Connexin 43 (Cx43) is one of the gap junction proteins which are compounds of transmembrane proteins and transports the small-molecular-weight chemicals up to 2 kDa. Lacking of Cx43 influences the junctional protein, induces autophagy and apoptosis in somatic cells. However, the function of Cx43 in porcine early embryos is still unknown. Aim to find out the molecular mechanism of Cx43 on the developmental competence in early porcine embryos, Cx43 dsRNA (1 ㎍/㎕) was microinjected into the parthenogenetically activated porcine zygotes. Blastocyst rate (treatment, 8.8±1.6% vs. control, 38.6±4.3%) and total cell numbers in the blastocyst (treatment, 20.7±3.5 vs. control, 39.8±4.1) were significantly reduced following Cx43 knocking down. Results from FITC-dextran and Western blot assay show that knock down (KD) of Cx43 significantly increased membrane permeability through down regulation of genes which are component of both adherence and tight junction in the porcine blastocyst. Reactive oxygen species (ROS) was significantly increased in the Cx43 KD group compared to control. In addition, KD of Cx43 activated Caspase 3 and significantly increased ATG8 expression, induced autophagy and apoptosis. Results suggest that KD of Cx43 influences preimplantation porcine embryo development via increasing membrane permeability and ROS generation, and inducing autophagy and apoptosis.

Melatonin (N-aceyl-5-methoxytryptamine) is the major hormone of the pineal gland. Melatonin and its metabolic derivatives possess extensive free-radical scavenging abilities and played critical roles in antioxidative stress, resisting apoptotic cell death. Melatonin also could enhance mitochondrial biogenesis in rats with carbon tetrachloride-induced liver fibrosis. In addition, melatonin attenuates myocardial ischemia/reperfusion injury by reducing oxidative stress damage via activation of SIRT1 signaling in a melatonin receptor 2-dependent manner. Activation or overexpression of SIRT1 could enhance mitochondrial biogenesis and function by inducing PGC-1α expression and deacetylation. The aim of this study was to investigate if melatonin enhances mitochondrial biogenesis and function via activation of melatonin receptor 2/SIRT1/PGC1-α Pathway. The results showed that Melatonin rescued rotenone-induced impairment of porcine embryo development. Treatment with rotenone could increase oxidative stress and apoptosis. Rotenone impaired mitochondrial functions by disrupting mitochondrial membrane potential, reducing mitochondrial DNA copy number and ATP production. Melatonin could improve SIRT1 and PGC-1α expression, inducing mitochondrial biogenesis. Rotenone-induced mitochondrial dysfunction and ATP deficiency was rescued by melatonin treatment, the oxidative stress and apoptosis was significantly decreased. Inhibition of melatonin receptor 2 or Knockdown of SIRT1 abolished the protective effects of melatonin on rotenone-induced impairments. Therefore, melatonin enhanced mitochondrial biogenesis and function, protected against rotenone-induced impairments.

Thiamethoxam (TMX) is a neonicotinoid insecticide. Residues of TMX have been detected in various crops. Although it has specific high toxicity to insects and is designed to exterminate them, the toxicity has also found in mammals recently. Differ from acetylcholine toxicity, TMX has peroxide toxicity in mammals. Matured oocytes have the capacity of fertilization, but oocytes own abundant mitochondria and its maturation is vulnerable to reactive oxygen species (ROS). Excessive production of reactive oxygen species (ROS) can override antioxidant defenses, produce oxidative stress and DNA damage that triggers apoptosis and necrosis in organisms. However little is known about the harm of ROS induced by TMX during oocytes maturation. Here, bovine germ-vesicle (GV) oocytes were cultured to metaphase of the second meiosis (MII) stage in vitro with or without TMX. During this process, oocytes were evaluated by various methods. Microscopic examination showed that 1.6 mM TMX significantly inhibited the maturation process in which oocytes were arrested before MI stage or between MI and MII stage. Correspond to this two periods, immunofluorescence staining and enzyme activity analysis showed that active CDC25 and CDC2 reduced in TMX group compared to control; time lapse and immunofluorescence staining gave results that Cyclin B could not be degraded, actin cap could not form, and Bub3 could not be removed from kinetochores. In addition, MII oocytes exposed to TMX showed disordered chromosomes and spindle. To study further, oocytes cultured for 24 h were analyzed. On the one hand, these oocytes in TMX group accumulated more ROS and produced significantly decreased mitochondrial membrane potential and increased apoptotic signal compared to control by methods of quantities for dichlorodihydrofluorescein diacetate (DCHFDA), 5,5′,6,6′-Tetrachloro-1,1′,3,3′-tetraethyl-imidacarbocyanine iodide and Annexin-V, but the level of γH2AX protein in TMX group did not decline significantly compared with control. On the another hand, these oocytes were activated to be parthenogenetic embryos and cultured. Assessment for embryo development showed decreased rates of cleavage, morula and blastocyst in TMX group compared to control in vitro. In conclusion, these results suggest that ROS induced by TMX results in dysfunction of mitochondria and apoptosis, which block bovine oocytes to MI stage, trap them at AI/TI stage and trigger disordered chromosomes and spindle at MII stage. Additionally, MII oocytes with poor qualities result from TMX lose abilities to cleavage and develop to be morulae and blastocysts.

The porcine zygotic genome activation occurs along with global epigenetic remolding at the 4-cell stage. The histone acetylation, regulating DNA transcription, replication and so on, requires adequate acetyl-CoA. Acetyl-CoA produced by translocated pyruvate dehydrogenase in the nucleus of mammalian cells has been reported, which is commonly considered locating in the mitochondria. To find out whether the nuclear pyruvate dehydrogenase regulating the histone acetylation by controlling generation of acetyl-CoA, a multiple sgRNAs-CRISPR/Cas9 targeting strategy was employed to generate a pyruvate dehydrogenase E1 alpha1 (Pdha1) knockout (KO) parthenogenetic embryo model. Results showed that the targeting efficiency of Pdha1 reached more than 90%. Hence, this model was used in the subsequent experiments. Furthermore, a translocation of Pdha1 during zygotic genome activation was found by immunofluorescent staining and was significantly inhibited by Pdha1 KO. Meanwhile, the 8-cell stage embryo rate significantly decreased after 72 h (24.19% vs 12.53%, control vs Pdha1 KO), indicating a 4-cell arrest. In addition, the nuclear histone acetylation level significantly decreased when Pdha1 was KO. To determine whether the zygotic genome transcription was affected, the qPCR was performed and showed that the mRNA level of Eif1A, Acly, Sqle and Pdha1 all dropped significantly in the Pdha1 KO group compared to the control. In conclusion, the translocated Pdha1 generates acetyl-CoA for histone acetylation inside the nucleus of porcine embryos, which promotes the zygotic genome activation of porcine embryos.

The acetyltransferase Tip60 (Kat5) is a member of the MYST family of HATs that was initially identified as a cellular protein. TIP60 acetylates histone and non-histone proteins, and is involved in diverse biological processes, including apoptosis, cell cycle, and DNA damage responses. In this study, a specific inhibitor of TIP60, Nu 9056, was used to study the function and its regulatory mechanism of Tip60 in the porcine preimplantation embryonic development. The results showed that inhibition of TIP60 impaired the embryonic development due to induce DNA damage through ATM-p53-p21 pathway, it was evidenced by expression of γH2A in the nuclei of blastocysts. In addition, TIP60 inhibition decreased efficiency of DNA repair by regulating P53 binding protein 1 expression. Furthermore, autophagy was induced following TIP60 inhibition through modulating microtubule-associated protein 1A/1B-light chain 3 expression. In conclusion, the results suggest that TIP60 plays a critical role in early embryonic development via regulation of DNA damage and its repairs.

Fatty acid synthesis (FASN) is an enzyme responsible for the de novo synthesis of long-chain fatty acids. During oncogenesis, FASN plays a role in growth and survival rather than acting within the energy storage pathways. Here, the function of FASN during early embryonic development was studied using its specific inhibitor C75. We found that the presence of the inhibitor reduced blastocyst hatching. FASN inhibition decreased Cpt1 expression, leading to a reduction in mitochondrial copy numbers and ATP content. This inhibition of FASN results in the down-regulation of the AKT pathway, thereby triggering apoptosis through the activation of the p53 pathway. Activation of the apoptotic pathways also leads to increased accumulation reactive oxygen species and autophagy. In addition, the FASN inhibitor can impair cell proliferation, a parameter of blastocyst quality for outgrowth. The level of OCT4, an important factor in embryonic development, decreased after treatment with the FASN inhibitor. These results show that FASN exerts an effect on the early embryonic development by regulation of both fatty acid oxidation and the AKT pathway in pigs.

PP2A-B55α, a regulatory subunit of PP2A plays an important roles in regulating cell proliferation and survival. However, the functions for PP2A-B55α in mouse early embryo development is not clear. The objective of present were to investigate the expression patterns and to explore its biological function during mouse early development. Thetranscripts of PP2A-B55α were detected at all developmental stages in mouse embryo and decreased during embryo development. Immunostaining revealed that PP2A-B55α was present in both the nucleus and cytoplasm in early cleavage stage embryos. In the late embryonic development, PP2A-B55α was predominantly located in the cytoplasm. Knockdown (KD) of PP2A-B55α using double strand RNA not affect the proportion of cleaved embryos, but resulted in significantly decreased development to blastocyst stage and reduced total cell number in blastocyst. KD PP2A-B55α is able to induce sustained DNA damage and reduced the transcripts of non-homologous end joining (NHEJ) or homologous recombination (HR) pathways relative genes in mouse early embryo. KD PP2A-B55αcaused apoptosis and increase the transcripts of pro-apoptotic genes in blastocyst. Furthermore, The KDPP2A-B55α showed significantly lower cell proliferating rates (from 5-Bromo-deoxyuridineassayresults) in blastocysts and to talareas of out growth potential was decreased. These observation provide novel in sight into PP2A-B55α expression patterns in mouse early embryos and down-regulation of PP2A-B55α negatively impacted blastocyst development, total cell number, DNA damage, apoptosis, and proliferation and post-hatchingevents.

Unlike somatic cells mitosis, germ cell meiosis consists of two consecutive rounds of divisions that segregate homologous chromosomes and sister chromatids, respectively. The meiotic oocyte is characterized by an absence of centrioles and asymmetric divisions. Centriolin is a relatively novel centriolar protein that functions in mitotic cell cycle progression and cytokinesis. Here, we explored the function of centriolin in meiosis and showed that it was localized to meiotic spindles, and concentrated at the spindle poles and midbody during oocyte meiotic maturation. Unexpectedly, knockdown of centriolin in oocytes with either siRNA or Morpholino micro-injection, did not affect meiotic spindle organization, cell cycle progression, or cytokinesis (as indicated by polar body emission), but led to a failure of peripheral meiotic spindle migration; and symmetric division or large polar body emission. These data suggest that, unlike in mitotic cells, the centriolar protein centriolin does not regulate cytokinesis, but plays an important role in regulating asymmetric division of meiotic oocytes.

In the present study, we examined potential roles of glucose and pyruvate in nuclear and cytoplasmic maturation of porcine oocytes. In the presence and absence of 10% porcine follicular fluid (PFF), either 5.6 mM glucose or 2mM pyruvate effect on meiotic maturation and followed development ability. However, DOs doesn't take full advantage of the glucose in medium, only pyruvate can increase MII rate and follow early embryo development ability significance. COCs were matured with 200 uM pentose phosphate pathway (PPP) inhibitor (dehydroepiandrosterone, DHEA) or 2 μM glycolysis inhibitor (iodoacetate, IA), significantly lower levels of GHS in the DHEA an IA treated oocytes and the levels of ROS were higher significantly in the DHEA treated oocytes, treatment with DHEA significantly reduced the intra-oocyte ATP and NADPH level. Blastocysts from DHEA or IA treated group also presented higher apoptosis levels, meanwhile, the percentage of proliferating cells was dramatically lower than the non-treated group. In conclusion, our results suggest that 10% PFF promoted oocytes make full use of energy, glucose metabolism during in vitro maturation inseparable from the cumulus cells, PPP and glycolysis promoted porcine oocytes cytoplasmic maturation by supplying energy and reducing oxidative stress.

Heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1) have a important role in influence of pre-messenger RNA (pre-mRNA) processing and mRNA metabolism and transportation in cells. Recently, hnRNP A2/B1 can recognize m6A modifications on pre-mRNA or pre-miRNA and affect alternative splicing and miRNA processing in HeLa Cells. However, roles of hnRNP A2/B1 in various cells and tissues, especially in elary embryo development, are unclear. Here, we investigated the temporal and spatial expression patterns of hnRNPA2B13 during mammalian early embryo development. In mouse, hnRNPA2B1 was localized at the nucleus after 1-cell stage, however, hnRNPA2B1 was expressed after 2-cell stage in pig. Then, knockdown of hnRNP A2/B1 induced by RNA interference (RNAi) was used to analyze the effect of hnRNP A2/B1 in preimplantation develop in pigs. Knockdown of hnRNP A2/B1 delayed embryo development. Interestingly, ICM marker OCT4 and Sox2 was significantly decreased in blastocyst stage. mRNA expression show that transcription factors which is Pou5f1, Sox2, Nanog, Cdx2 and AP2γwas decreased the transcription levels without the changing of junction protein, ZO-1, occludin, and CXADR. Outgrowth results indicated that knock-down of hnRNPA2B1 embryos cannot format the colony. Knock-down of Methyltransferase like 3(METTL3) embryos mislocalized the hnRNPA2/B1 at the nucleus. In summary, the expression patterns of hnRNPA2/B1 differ between mouse and porcine embryos, and these differences may reflect species-specific functions during preimplantation embryo development. Our results suggested that hnRNPA2/B1 is necessary for newly synthesis of mRNA related with transcription factor, and early embryo development by the RNA epigenetic modification.

CDK2 inhibition plays a central role in DNA damage–induced cell cycle arrest and DNA repair. However, whether CDK2 also influences early porcine embryo development is unknown. In this study, we examined whether CDK2 is involved in the regulation of oocyte meiosis and early embryonic development of porcine. We found that disrupting CDK2 activity with RNAi or an inhibitor did not affect meiotic resumption or MII arrest. However, CDK2 inhibitor-treated embryos showed delayed cleavage and ceased development before the blastocyst stage. Disrupting CDK2 activity is able to induce sustained DNA damage as demonstrated by the formation of distinct γH2AX foci in nuclei of day 3- and day 5-embryos. Inhibiting CDK2 triggers a DNA damage checkpoint by activating of the ATM-P53-P21 pathway. However, the mRNA expression of genes involved in non-homologous end-joining (NHEJ) or homologous recombination (HR) pathways for double strand break (DSB) repair reduced after administering CDK2 inhibitor to 5-day-old embryos. Furthermore, CDK2 inhibition caused apoptosis in day 7 blastocysts. Thus, our results indicate that an ATM-P53-P21 DNA damage checkpoint is intact in the absence of CDK2; however, CDK2 is important for proper repair of the damaged DNA by either directly or indirectly influencing DNA repair-related gene expression.

Spindlin1(Spin1), a meiotic spindle-binding protein that is highly expressed in cancer cells. Spindle-binding was dependent on its phosphorylation status, which was partially regulated by Mos/MAP kinase pathway. Nevertheless, the biologic roles of Spin1 in oocytes maturation are still largely unknown. For exploring the function of Spin1 in porcine oocyte maturation, Knockdown and overexpression methods were employed to the present study. Spin1 mRNA were enriched in maternal stages, from germinal vesicle - to 2 cell - stage, but sharply decreased after 4 cell stage, zygotic genome activation. Protein of SPIN1 was localized in spindle-chromatin complex during the metaphase I and metaphase II stages. Knockdown of Spin1 did not affect the first polar body extrusion, however, Spin1 depletion caused mitotic spindle defects, chromosome instability and pronuclear formation in metaphase II stage. Percentage of 2cell, 4cell embryos and blastocyst formation were significantly reduced in knockdown group compared with control, but cell numbers in blastocyst were no difference between control and knockdown groups. Another hand, Oocyte failed to maturation and induced metaphase I arrest following Spin1 over-expression. In conclusion, Spin1 is involved in the spindle formation and maintenance during oocytes meiotic maturation in pigs.

The present study assessed the effect of FSH and LH on oocyte meiotic, cytoplasmic maturation and on the expression level and polyadenylation status of several maternal genes. Cumulus-oocyte complexes were cultured in the presence of FSH, LH, or the combination of FSH and LH. Significant cumulus expansion and nuclear maturation was observed upon exposure to FSH alone and to the combination of FSH and LH. The combination of FSH and LH during entire IVM increased the mRNA level of four maternal genes, C-mos, Cyclin B1, Gdf9 and Bmp15, at 28 h. Supplemented with FSH or LH significantly enhanced the polyadenylation of Gdf9 and Bmp15; and altered the expression level of Gdf9 and Bmp15. Following parthenogenesis, the exposure of oocytes to combination of FSH and LH during IVM significantly increased cleavage rate, blastocyst formation rate and total cell number, and decreased apoptosis. In addition, FSH and LH down-regulated the autophagy gene Atg6 and upregulated the apoptosis gene Bcl-xL at the mRNA level in blastocysts. These data suggest that the FSH and LH enhance meiotic and cytoplasmic maturation, possibly through the regulation of maternal gene expression and polyadenylation. Overall, we show here that FSH and LH inhibit apoptosis and autophagy and improve parthenogenetic embryo competence and development.

Low efficiency of somatic cell nuclear transfer (SCNT) is attributed to incomplete reprogramming of transfered nu-clei into oocytes. Trichostatin A (TSA), histone deacetylase inhibitor and 5-aza-2’deoxycytidine (5-aza-dC), DNA methy-lation inhibitor has been used to enhance nuclear reprogramming following SCNT. However, it was not known molec-ular mechanism by which TSA and 5-aza-dC improve preimplantation embryo and fetal development following SCNT. The present study investigates embryo viability and gene expression of cloned porcine preimplantation embryos in the presence and absence of TSA and 5-aza-dC as compared to embryos produced by parthenogenetic activation. Our results indicated that TSA treatment significantly improved development. However 5-aza-dC did not improve development. Presence of TSA and 5-aza-dC significantly improved total cell number, and also decreased the apoptot-ic and autophagic index. Three apoptotic-related genes, Bak, Bcl-xL, and Caspase 3 (Casp3), and three autophagic-re-lated genes, ATG6, ATG8, and lysosomal-associated membrane protein 2 (LAMP2), were measured by real time RT-PCR. TSA and 5-aza-dC treatment resulted in high expression of anti-apoptotic gene Bcl-xL and low pro-apoptotic gene Bak expression compared to untreated NT embryos or parthenotes. Furthermore, LC3 protein expression was lower in NT-TSA and NT-5-aza-dC embryos than those of NT and parthenotes. In addition, TSA and 5-aza-dC treated embryos displayed a global acetylated histone H3 at lysine 9 and methylated DNA H3 at lysine 9 profile similar to the parthenogenetic blastocysts. Finally, we determined that several DNA methyltransferase genes Dnmt1, Dnmt3a and Dnmt3b. NT blastocysts showed higher levels Dnmt1 than those of the TSA and 5-aza-dC blastocysts. Dnmt3a is lower in 5-aza-dC than NT, NTTSA and parthenotes. However, Dnmt3b is higher in 5-aza-dC than NT and NTTSA. These results suggest that TSA and 5-aza-dC positively regulates nuclear reprogramming which result in modulation of apoptosis and autophagy related gene expression and then reduce apoptosis and autophagy. In addition, TSA and 5-aza-dC affects the acetylated and methylated status of the H3K9.

The objective of this study was to examine the effects of high concentrations of glucose on porcine parthenotes developing in vitro. Addition of 55 mM glucose to the culture medium of embryos at the four-cell-stage significantly inhibited blastocyst formation, resulting in fewer cells in blastocyst-stage embryos and increased levels of apoptosis and autophagy compared to control. Quantitative reverse transcriptase (RT) PCR analysis revealed that the expression of pro-apoptotic genes (Caspase 3, Bax and Bak) and autophagy genes (Atg6 and Atg8/Lc3) were increased significantly by the addition of 55 mM glucose to the culture medium compared to control. MitoTracker Green fluorescence revealed a decrease in the overall mitochondrial mass compared to control. However, the addition of 55 mM glucose had no effect on mRNA expression of the nuclear DNA-encoded mitochondrial-related genes, cytochrome oxidase (Cox) 5a, Cox5b and Cox6b1. These results suggest that hyperglycemia reduced the mitochondrial content of porcine embryos developing in vitro and that this may hinder embryonic development to the blastocyst stage and embryo quality by increasing apoptosis and autophagy in these embryos.