Parthenogenetic Activation Embryos Research Articles

Dual effect of fetal bovine serum on early development depends on stage-specific reactive oxygen species demands in pigs.

Despite the application of numerous supplements to improve in vitro culture (IVC) conditions of mammalian cells, studies regarding the effect of fetal bovine serum (FBS) on mammalian early embryogenesis, particularly in relation to redox homeostasis, are lacking. Herein, we demonstrated that early development of in vitro-produced (IVP) porcine embryos highly depends on the combination of FBS supplementation timing and embryonic reactive oxygen species (ROS) requirements. Interestingly, FBS significantly reduced intracellular ROS levels in parthenogenetically activated (PA) embryos regardless of the developmental stage. However, the beneficial effect of FBS on early embryogenesis was found only during the late phase (IVC 4–6 days) treatment group. In particular, developmental competence parameters, such as blastocyst formation rate, cellular survival, total cell number and trophectoderm proportion, were markedly increased by FBS supplementation during the late IVC phase. In addition, treatment with FBS elevated antioxidant transcript levels during the late IVC phase. In contrast, supplementation with FBS during the entire period (1–6 days) or during the early IVC phase (1–2 days) greatly impaired the developmental parameters. Consistent with the results from PA embryos, the developmental competence of in vitro fertilization (IVF) or somatic cell nuclear transfer (SCNT) embryos were markedly improved by treatment with FBS during the late IVC phase. Moreover, the embryonic stage-specific effects of FBS were reversed by the addition of an oxidant and were mimicked by treatment with an antioxidant. These findings may increase our understanding of redox-dependent early embryogenesis and contribute to the large-scale production of high-quality IVP embryos.

Meiotic arrest as an alternative to increase the production of bovine embryos by somatic cell nuclear transfer.

This study aimed to evaluate the effect of meiotic arrest using phosphodiesterase type 3A (PDE 3A) inhibitors, cilostamide and C-type natriuretic peptide (NPPC), on pre-maturation (PM) of oocytes to be used in the production of cloned embryos. Nuclear maturation, in vitro embryo production (IVP), somatic cell nuclear transfer (SCNT) and parthenogenetic activation (PA), and total cells number of cloned embryos were evaluated. The results were analysed by chi-squared and Kruskal-Wallis test with a P-value 0.05) between control and PM, both for cleavage (78.2% and 76.9%) and blastocyst (35.5% and 29.3%) rates. After SCNT, cleavage rate was also similar (P > 0.05) between control and PM (66% and 51.9%) however, blastocyst rate was lower (P < 0.05) in the PM group than in the control group (7.4% and 30.2%). After 6 h of PM with 100 nM of NPPC, approximately 84.9% of the oocytes remained at GV. No difference was found between control and PM in cleavage (69.2% and 76.1%) and blastocyst rates (37,4% and 35%) after IVP. Similarly, no differences between PM and control groups were observed for cleavage (69.2% and 68.4%) and blastocyst (24.4% and 21.5%) rates. SCNT and PA embryos from control or PM oocytes had similar total cell number. It can be concluded that PM for 6 h with 100 nM NPPC is feasible for cloned embryo production without affecting embryo outcome.

The effects of canthaxanthin on porcine oocyte maturation and embryo development in vitro after parthenogenetic activation and somatic cell nuclear transfer.

The objective of this study was to examine the effects of canthaxanthin (Cx) treatment during in vitro maturation (IVM) of porcine oocytes on embryonic development after parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT), on intracellular glutathione (GSH) and reactive oxygen species (ROS) levels in mature oocytes, and on gene expression in both PA- and SCNT-derived blastocysts. To determine the optimal effective concentration of Cx, porcine oocytes were cultured in IVM medium supplemented with various concentrations (0, 20, 40 and 80μM) of Cx for 22 hr. Compared to other groups, supplementation with 40μM Cx significantly improved blastocyst formation rates after PA (p<.05), but no significant differences were observed among groups in total blastocyst cell numbers. Subsequently, oocytes were cultured in IVM medium supplemented with or without 40μM Cx. Oocytes treated with 40μM Cx showed significantly increased cleavage and blastocyst formation rates after SCNT compared to the control group (p<.05). Moreover, significantly increased intracellular GSH and reduced ROS levels were observed in the Cx-treated group (p<.05). In addition, both PA- and SCNT-derived blastocysts from the 40μM Cx-treated group showed significantly increased mRNA expression of Bcl2 and Oct4 and decreased Caspase3 expression level (p<.05), when compared with the control group. PA-derived blastocysts from the 40μM Cx-treated group also exhibited significantly decreased expression of Bax (p<.05). Our results demonstrated that treatment with 40μM Cx during IVM improves the developmental competence of PA and SCNT embryos. Improvement of embryo development by Cx is most likely due to increased intracellular GSH synthesis, which reduces ROS levels in oocytes, and it may also positively regulate apoptosis- and development-related genes.

Iloprost supports early development of in vitro-produced porcine embryos through activation of the phosphatidylinositol 3-kinase/AKT signalling pathway

Despite evidence of the presence of prostaglandin (PG) I2 in mammalian oviducts, its role in early development of in vitro-produced (IVP) embryos is largely unknown. Thus, in the present study we examined the effects of iloprost, a PGI2 analogue, on the in vitro developmental competence of early porcine embryos and the underlying mechanism(s). To examine the effects of iloprost on the development rate of IVF embryos, iloprost was added to the in vitro culture (IVC) medium and cultured for 6 days. Supplementation of the IVC medium with iloprost significantly improved developmental parameters, such as blastocyst formation rate, the trophectoderm:inner cell mass ratio and cell survival in IVF and parthenogenetically activated (PA) embryos. In addition, post-blastulation development into the expanded blastocyst stage was improved in iloprost-treated groups compared with controls. Interestingly, the phosphatidylinositol 3-kinase (PI3K)/AKT signalling pathway was significantly activated by iloprost supplementation in a concentration-dependent manner (10-1000nM), and the beneficial effects of iloprost on the early development of porcine IVF and PA embryos was completely ablated by treatment with 2.5μM wortmannin, a PI3K/AKT signalling inhibitor. Importantly, expression of the PI3K/AKT signalling pathway was significantly reduced in somatic cell nuclear transfer (SCNT) compared with IVF embryos, and iloprost supported the early development of SCNT embryos, as was the case for IVF and PA embryos, suggesting a consistent effect of iloprost on the IVC of IVP porcine embryos. Together, these results indicate that iloprost can be a useful IVC supplement for production of IVP early porcine embryos with high developmental competence.

Supplementation with spermine during in vitro maturation of porcine oocytes improves early embryonic development after parthenogenetic activation and somatic cell nuclear transfer.

Spermine plays an important role in protection from reactive oxygen species (ROS) in bacteria, yeast, and mammalian cells, but there are few studies on the effects of spermine on porcine oocyte maturation and subsequent embryo development. The aim of this study was to determine the effects of spermine on in vitro maturation (IVM) of porcine oocytes and their developmental competence after parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT). We evaluated nuclear maturation, intracellular glutathione (GSH), and ROS levels in oocytes, and their subsequent embryonic development, as well as gene expression in mature oocytes, cumulus cells, and PA blastocysts. After treatment with various concentrations of spermine in IVM culture medium, there was no significant difference in nuclear maturation rate. However, spermine treatment groups (10- 500 µM) showed significantly increased intracellular GSH levels and decreased ROS levels compared to the control ( < 0.05). Furthermore, 10 µM spermine supported significantly higher blastocyst formation rates after PA than the control group ( < 0.05). According to the optimal condition from the PA results, we investigated the effects of 10 µM spermine on SCNT, and it also significantly improved blastocyst formation rates compared with the control group ( < 0.05). In evaluating the effects of 10 µM spermine on gene expression, there was significantly lower expression of a proapoptotic gene () and higher expression of an antiapoptotic gene () in cumulus cells ( < 0.05). was increased in spermine-treated oocytes. Levels of transcription for and were significantly increased in PA blastocysts. In conclusion, 10 µM spermine supplementation during IVM improved the development of porcine PA and SCNT embryos by increasing intracellular GSH, scavenging ROS levels, and regulating gene expression.

58 EFFECT OF LYSOPHOSPHATIDIC ACID ON PORCINE OOCYTE IN VITRO MATURATION AND SUBSEQUENT EMBRYONIC DEVELOPMENT AFTER PARTHENOGENETIC ACTIVATION AND IVF

Lysophosphatidic acid (LPA) is a signalling molecule derived from phospholipid, known to have biological activities such as stimulating cell proliferation, differentiation, and migration. The purpose of this study was to investigate the effect of LPA on in vitro maturation (IVM) of porcine oocytes and subsequent embryonic development after in vitro fertilization (IVF) and parthenogenetic activation (PA). We examined nuclear maturation, intracellular glutathione (GSH), and reactive oxygen species (ROS) levels and subsequent embryonic development after IVF in porcine oocytes matured in TCM-199 media containing either 0, 10, 30, or 60 μM LPA (No. of cultured oocytes 225, 225, 230, and 226, respectively). All data were compared for all groups using one-way ANOVA, followed by Duncan’s multiple range test. After 44 h of IVM, no significant difference was observed for nuclear maturation from the different (0, 10, 30, and 60 μM) LPA treatment groups (86.61, 87.48, 92.97, and 88.69%, respectively) compared with the control (P &lt; 0.05). The 30 μM LPA treated group exhibited a significant (P &lt; 0.05) increase in intracellular GSH levels and decrease in intracellular ROS levels compared with other LPA-treated groups. Oocytes matured with 30 μM LPA during IVM had significantly (P &lt; 0.05) higher cleavage rates after PA (88.50%) than other LPA-treated groups (79.42, 83.87, and 83.65%, respectively). Blastocyst formation rates following PA increased up to 30 μM LPA, but the rates decreased in the 60 μM LPA-treated group (49.64, 53.28, 57.00, and 51.09%, respectively). However, a statistical difference was not observed (P &lt; 0.05). Upon evaluation of embryonic competence following IVF, treatment with 30 μM LPA during IVM significantly increased cleavage rates (70.44%; P &lt; 0.05) compared with 0 and 60 μM LPA-treated groups (61.51 and 65.27%, respectively). Blastocyst formation rates improved with increasing concentrations of LPA up to 30 µM; however, the rates decreased in the 60 μM LPA-treated group (26.34, 30.10, 33.26, and 27.77%, respectively). However, like the preceding PA blastocyst formation rates, a statistical difference was not observed (P &lt; 0.05). In conclusion, treatment with 30 μM LPA during IVM improved the developmental potential of PA and IVF porcine embryos by increasing the intracellular GSH level, thereby decreasing the intracellular ROS level during oocyte maturation. This work was supported, in part, by a grant from the Cooperative Research Program for Agriculture Science &amp; Technology Development (Project No. PJ011077, PJ011288), Rural Development Administration, and the National Research Foundation of Korea Grant funded by the Korean Government (NRF-2013R1A2A2A04008751). These are the results of a study from the Leaders INdustry-University Cooperation Project 2015-B-0013–010118, supported by the Ministry of Education, Republic of Korea.

The Efficient Derivation of Trophoblast Cells from Porcine In Vitro Fertilized and Parthenogenetic Blastocysts and Culture with ROCK Inhibitor Y-27632.

Trophoblasts (TR) are specialized cells of the placenta and play an important role in embryo implantation. The in vitro culture of trophoblasts provided an important tool to investigate the mechanisms of implantation. In the present study, porcine trophoblast cells were derived from pig in vitro fertilized (IVF) and parthenogenetically activated (PA) blastocysts via culturing in medium supplemented with KnockOut serum replacement (KOSR) and basic fibroblast growth factor (bFGF) on STO feeder layers, and the effect of ROCK (Rho-associated coiled-coil protein kinases) inhibiter Y-27632 on the cell lines culture was tested. 5 PA blastocyst derived cell lines and 2 IVF blastocyst derived cell lines have been cultured more than 20 passages; one PA cell lines reached 110 passages without obvious morphological alteration. The derived trophoblast cells exhibited epithelium-like morphology, rich in lipid droplets, and had obvious defined boundaries with the feeder cells. The cells were histochemically stained positive for alkaline phosphatase. The expression of TR lineage markers, such as CDX2, KRT7, KRT18, TEAD4, ELF5 and HAND1, imprinted genes such as IGF2, PEG1 and PEG10, and telomerase activity related genes TERC and TERF2 were detected by immunofluorescence staining, reverse transcription PCR and quantitative real-time PCR analyses. Both PA and IVF blastocysts derived trophoblast cells possessed the ability to differentiate into mature trophoblast cells in vitro. The addition of Y-27632 improved the growth of both PA and IVF blastocyst derived cell lines and increased the expression of trophoblast genes. This study has provided an alternative highly efficient method to establish trophoblast for research focused on peri-implantation and placenta development in IVF and PA embryos.

Expression pattern of OCT 4, NANOG and HSP 90 β gene in oocytes and various stages of in vitro produced sheep embryos

The study was conducted to assess the expression pattern of pluripotent genes (OCT 4 and NANOG) and stress response gene HSP 90 ß by quantitative real time polymerase chain reaction (qRT-PCR) in immature and mature oocytes and 2 cell, 4 cell, morula stages of in vitro fertilized (IVF) and parthenogenetically activated (PA) preimplantation ovine embryos to investigate the similarity between them in turn for the establishment of embryonic stem cells (ESCs) from parthenote embryos. The pluripotent related genes showed almost similar pattern of expression between IVF and PA embryos at all the developmental stages which indicated that PA embryos could be used as an alternate source for the production of embryonic stem cells. The stress response gene showed increased levels after in vitro maturation and non significant differences between IVF and PA embryos, thus, indicating no significant differences between the quantum of stress experienced by the 2 groups of embryos which would not affect the development of embryo quality and in turn affect the parthenote embryonic stem cells (PESCs).

Melatonin protects porcine oocyte invitro maturation from heat stress.

Melatonin is a pleiotropic molecule which plays an important role in animal reproductive activities. Because of the increased global warming, the impact of heat stress (HS) on stockbreeding has become an inevitable issue to be solved. To investigate the potential effects of melatonin on the invitro maturation of porcine oocyte under the HS, a HS model for porcine oocyte maturation has been used in this study and the different concentrations of melatonin (10(-6) -10(-9) m) were also tested for their protective effects on oocytes. The polar body rate, the index of the nuclear maturation of the oocytes, and the cleavage rate as well as the blastocyst rate were measured to evaluate the developmental competence of the oocytes after parthenogenetic activation (PA). The results showed that HS [in vitro maturation (IVM) 20-24hr, 42°C] significantly reduced the polar body rate of oocytes and the blastocyte rate of porcine PA embryos, while melatonin (10(-7) m) application not only improved polar body rate and blastocyte rate, but also preserved the normal levels of steroid hormone which is disrupted by HS. The presence of melatonin (10(-7) m) during the oocyte maturation under the HS reduced reactive oxygen species (ROS) formation, enhanced glutathione (GSH) production, inhibited cell apoptosis, and increased the gene expressions of SIRT1, AKT2, and Polg2. Importantly, the endogenously occurring melatonin of cumulus-oocyte complexes was significantly induced by HS. The results indicated that melatonin application effectively protected the oocytes from HS. These observations warranted the further studies invivo regarding to improve the reproductive activities of animals under the global warming environment.

Cryotop vitrification of porcine parthenogenetic embryos at the early developmental stages

The objective of this study was to evaluate the effects of early developmental stages at which Cryotop vitrification is performed on subsequent survival and in vitro development of porcine parthenogenetic activation embryos. The zygotes that were cultured for 4, 8, and 18 hours post electric activation (h.p.a.) and two- and four-cell embryos were vitrified, warmed, and continuously cultured for the remaining period. The zygotes vitrified at 4, 8, and 18 h.p.a. showed similar percentages of survival, cleavage, and blastocyst formation. No difference in viability was observed after vitrification of two- and four-cell embryos, but the embryos vitrified at the two-cell stage exhibited significantly higher blastocyst formation rate than those vitrified at the four-cell stage. However, vitrifying embryos resulted in significantly decreased survival and development rates, regardless of the developmental stage of the embryos. In addition, the final developmental stage, diameter, apoptotic index, and the number of inner cell mass, trophectoderm, and total cells of blastocysts derived from embryos vitrified at any stage of the early culture were similar to those of fresh blastocysts. In conclusion, our data indicate that the early-stage porcine parthenogenetically activated embryos including the zygote, two cells, and four cells have a high ability to survive cryopreservation; these viable embryos after vitrification can produce respectable development rates and good-quality blastocysts.

Colcemid treatment during oocyte maturation improves preimplantation development of cloned pig embryos by influencing meiotic progression and cytoplasmic maturation.

The objective of this study was to examine the effects of colcemid treatment during oocyte in vitro maturation (IVM) and embryonic development after parthenogenetic activation (PA) and somatic-cell nucleus transfer (SCNT) in pigs. Immature oocytes were treated with colcemid from 0 to 22, 38 to 42, or 0 to 22 hr followed by 38 to 42 hr during IVM (designated as COL0-22, COL38-42, and COL0-22/38-42, respectively). The proportion of oocytes reaching the germinal vesicle (GV)/GV breakdown (GVBD) stage after 22 hr of IVM was higher in COL0-22 (98.4%) than in controls not exposed to colcemid (68.7%). The proportion of metaphase-II (MII) oocytes after 30 hr of IVM was higher in control (79.6%) than in COL0-22 oocytes (61.7%); overall nuclear progression to the MII stage was not influenced by colcemid treatment by the end of the IVM period (93.8, 86.7, 86.8, and 84.8% for control, COL0-22, COL38-42, and COL0-22/38-42, respectively). COL0-22 oocytes showed higher intra-oocyte glutathione content (1.7 vs. 1.0-1.3 pixels/oocyte) and increased blastocyst formation after PA (68.7% vs. 42.5-52.2%) and SCNT (39.4% vs. 16.3-28.6%) than control, COL38-42, and COL0-22/38-42 oocytes. Colcemid treatment for 0-22 and 0-22/38-42 hr of IVM also stimulated the expression of cyclin-dependent kinase 1 (CDK1), proliferating cell nuclear antigen (PCNA), and extracellular signal-regulated kinase 2 (ERK2) mRNAs. Our results thus demonstrate that the presence of colcemid during the early stage of IVM stimulates preimplantation development of PA and SCNT porcine embryos by improving the cytoplasmic microenvironment.

Improvement in the blastocyst quality and efficiency of putative embryonic stem cell line derivation from porcine embryos produced in vitro using a novel culturing system.

Porcine embryonic stem cells (pESCs) have great potential for application in translational biomedical research, including xenotransplantation and disease models. Obtaining high-quality blastocysts is the most important factor in the isolation and colonization of primary ESCs and the establishment of ESC lines. In pigs, in vitro-derived blastocysts have a limited cell number compared to in vivo-derived blastocysts and show an indefinite inner cell mass, which may result in failure to establish pESC lines. In the present study, the effects of resveratrol (RES), granulocyte-macrophage colony stimulating factor (GM-CSF) and β-mercaptoethanol (β-ME) on the quality of blastocysts and the efficiency of colony derivation were investigated for the establishment of ESCs. A novel culturing system was developed in which 2 µM RES was added to the oocyte in vitro maturation (IVM) medium, and 10 ng/ml pGM-CSF and 10 µM β-ME were added to embryo in vitro culture (IVC) medium. This novel system showed significantly more parthenogenetic activation (PA) blastocysts (54.5 ± 1.8% vs. 43.4 ± 1.2%; P<0.05) and in vitro fertilization (IVF) blastocysts (36.9 ± 3.3% vs. 26.2 ± 2.9%; P<0.06) at day seven as compared with that in the control system. The PA and IVF blastocysts from the novel system showed a significantly greater hatching rate (P<0.05) and greater cell numbers (55.1 ± 2.0 vs. 45.6 ± 2.0; P<0.05 and 78.9 ± 6.8 vs. 58.5 ± 7.2; P<0.06, for PA and IVF, respectively) at day seven compared to that in the control system. After seeding on feeder cells, the PA blastocysts produced by the novel system showed a significantly increased rate of attachment (28.8 ± 3.9% vs. 17.2 ± 2.4%; P<0.062). Finally, two putative pESC lines from PA embryos produced by the novel system and one by the control system were established. In conclusion, the novel system improved blastocyst quality and increased the derivation efficiency of putative pESC lines from porcine PA and IVF embryos produced in vitro.

Antioxidative effect of carboxyethylgermanium sesquioxide (Ge-132) on IVM of porcine oocytes and subsequent embryonic development after parthenogenetic activation and IVF

Carboxyethylgermanium sesquioxide (Ge-132) is an organogermanium compound known to exert biological activities, such as antioxidant and anticancer effects. In this study, we investigated the effect of Ge-132 on the IVM of porcine oocytes via analysis of nuclear maturation, intracellular glutathione (GSH) and reactive oxygen species (ROS) levels, and subsequent embryonic development after parthenogenetic activation (PA) and IVF. After 40 hours of IVM, no significant difference in nuclear maturation was observed in the 100, 200, and 400 μg/mL of Ge-132 treatment groups (89.9%, 91.3%, and 90.4%, respectively) compared with the control group (89.0%). However, intracellular GSH levels in oocytes treated with 200 μg/mL of Ge-132 increased significantly (P < 0.05), and the 200 and 400 μg/mL of Ge-132 treatment groups exhibited a significant (P < 0.05) decrease in intracellular ROS levels compared with the control group. Oocytes matured with 200 and 400 μg/mL of Ge-132 during IVM displayed significantly higher cleavage rates (78.7% and 82.7% vs. 67.5%, respectively), and the 200 μg/mL of Ge-132 treatment group displayed higher blastocyst formation rates and greater total cell numbers after PA (59.5% and 67.8 vs. 38.2% and 55.3, respectively) than the control group. Furthermore, oocytes matured with 200 μg/mL of Ge-132 during IVM failed to display significantly higher blastocyst formation rates (31.6% vs. 36.7%) but exhibited greater total cell numbers after IVF (71.5 vs. 101.3, respectively) than the control group. We also found that the Ge-132–treated oocytes showed significantly higher messenger RNA (mRNA) expression levels of the oxidative-related gene Nrf-2 and lower mRNA expression levels of the proapoptotic gene Bax than the control group (P < 0.05). In conclusion, our results suggest that treatment with Ge-132 during IVM improves the developmental potential of PA and IVF porcine embryos by increasing the intracellular GSH levels, thereby decreasing the intracellular ROS levels and reducing oxidative stress–induced apoptosis, thereby regulating the mRNA expression of oocytes during oocyte maturation.

Sequential treatment with resveratrol-trolox improves development of porcine embryos derived from parthenogenetic activation and somatic cell nuclear transfer

We investigated the effect of resveratrol supplementation during IVM and/or trolox during IVC on the development of porcine embryos derived from parthenogenetic activation (PA) and SCNT. In this study, we evaluated intracellular glutathione (GSH) and reactive oxygen species (ROS) levels, gene expression in blastocysts, and embryonic development after PA and SCNT. To determine the combined effects of resveratrol during IVM and trolox during IVC on PA embryos, we selected optimal concentrations (2 μM of resveratrol and 200 μM of trolox) and designed four groups: (1) control, (2) resveratrol, (3) trolox, and (4) combined. All treatment groups showed significantly increased intracellular GSH levels and decreased ROS levels. Resveratrol supported significantly higher cleavage and blastocyst formation rates than the control (80.3% and 38.0% vs. 71.1% and 22.4%, respectively) by downregulating Bax/Bcl-2, Caspase-3, and Bak. Trolox showed significantly increased blastocyst formation rates (36.7%) compared with the control (22.4%) by downregulating only Caspase-3. The combined group had significantly higher cleavage and blastocyst formation rates and greater total cell numbers than the control (81.7%, 36.3%, and 67.1 vs. 71.1%, 22.4%, and 47.8, respectively) by downregulating Bax/Bcl-2, Caspase-3, and Bak. On the basis of these results, we applied sequential treatments with resveratrol and trolox to SCNT, and blastocyst formation rates and total cell numbers were significantly increased compared with the control (17.2% and 52.1 vs. 11.8% and 36.6, respectively), with increased GSH, decreased ROS levels, upregulated proliferating cell nuclear antigen, and downregulated Bax/Bcl-2 and Caspase-3. These results indicate that sequential treatment with resveratrol during IVM and trolox during IVC improved the development of PA and SCNT porcine embryos by regulating intracellular GSH, ROS levels, and gene expression.

Distribution and content of lipid droplets and mitochondria in pig parthenogenetically activated embryos after delipation

The present study examines the effect of delipation on developmental competence and the distribution pattern of lipid droplets (LDs) and mitochondria in parthenogenetically activated (PA) pig embryos. Mature oocytes were delipated by centrifugation after partial digestion of the zonae pellucidae, subjected to parthenogenetic activation after total removal of zonae pellucidae by pronase, and then cultured in vitro up to the blastocyst stage. The contents and distributions of LDs and mitochondria in the oocytes and/or embryos were observed by staining with Oil Red O and MitoTracker Red CMXRos, respectively. The LD and mitochondrial contents were significantly reduced by the delipation process, and only smaller LDs remained in the delipated oocytes and/or embryos. Their content remained constant from the metaphase II oocyte to the blastocyst stage, but they became gradually smaller as the oocytes and/or embryos developed. The distribution pattern of the LDs in the delipated embryos changed over time and in a manner different to that seen in the controls. In the early developmental stages (1- to 4-cell stages), they were distributed peripherally and formed a ring around the nucleus. However, by the blastocyst stage, a homogeneous distribution of LDs was observed in both the inner cell mass and trophectoderm. The distribution pattern of mitochondria also changed with the development of the delipated PA embryos and again, in ways different to those seen in the controls. In the early 1- to 4-cell stages, a peripheral distribution of mitochondrial foci was observed in each blastomere. However, in blastocysts, the mitochondria were homogeneously distributed throughout the inner cell mass and trophectoderm. Although the cleavage rate at the 2- and 4-cell stages of the PA embryos was not affected by delipation (95.83 ± 2.25% vs. 97.44 ± 0.67%; 79.17 ± 4.47% vs. 84.62 ± 1.19%), it was reduced significantly in the blastocyst compared with the controls (21.67 ± 3.78% vs. 49.36 ± 1.77%). The distribution pattern of the LDs in oocytes and/or embryos at different developmental stages, and that of the mitochondria in metaphase II oocytes, was affected by delipation. The developmental competence of porcine PA embryos would appear to be affected by delipation.

Toxicity evaluation of ethanol treatment during in vitro maturation of porcine oocytes and subsequent embryonic development following parthenogenetic activation and in vitro fertilization.

Ethanol is frequently used as a solvent in several techniques for in vitro production (IVP). It is also used for the parthenogenetic activation (PA) of oocytes. Although a number of studies have suggested that ethanol has detrimental effects on fibroblasts and neuronal cells, little attention has been paid to the effects of ethanol on porcine oocytes. Thus, the aim of this study was to evaluate the effects of the addition of ethanol to in vitro maturation (IVM) medium. We investigated the effects of ethanol (0, 1 and 3%) on the following parameters: nuclear maturation, intracellular glutathione (GSH) and reactive oxygen species (ROS) levels, and subsequent embryonic development following PA and in vitro fertilization (IVF). After 44 h of IVM, the 3% group showed a significant (P<0.05) decrease in nuclear maturation (34.0%) compared with the control group (70.3%). The 1 and 3% groups exhibited a significant (P<0.05) decrease in GSH levels and an increase in ROS levels compared with the control group. Compared with the control group, the 3% group had significantly (P<0.05) lower cleavage rates following PA (51.6 vs. 86.9%) and IVF (53.2 vs. 70.6%), as well as lower blastocyst formation rates and decreased total cell numbers following PA (11.3% and 31.8 vs. 53.6% and 65.4, respectively) and IVF (4.1% and 22.0 vs. 36.1% and 70.3, respectively). We evaluated the mRNA expression levels of DNA repair‑related and apoptosis‑related genes in the cumulus oocyte complexes (COCs). The 1% ethanol group showed significantly (P<0.05) higher mRNA expression levels of poly(ADP‑ribose) polymerase‑1 (PARP‑1), Bax, Bak and caspase‑3, and the 3% ethanol group had significantly (P<0.05) increased PARP‑1, Bax and caspase‑3 mRNA expression levels compared with the control group. Our results suggest that treatment with >1% ethanol during IVM exerts a toxic effect on the developmental potential of PA and IVF porcine embryos by decreasing the intracellular GSH level, thereby increasing the intracellular ROS level and upregulating the expression of apoptosis‑related genes.

Dynamic changes of histone H3 lysine 27 acetylation in pre-implantational pig embryos derived from somatic cell nuclear transfer

Histone H3 lysine 27 acetylation (H3K27ac) is an active epigenetic modification which has been revealed to be associated with active gene expression. It was hypothesized that H3K27ac might also participate in the porcine somatic reprogramming process during early development of SCNT-derived embryos. The spatial and temporal expression profiles of H3K27ac were investigated at different developmental stages in SCNT embryos compared with in vitro fertilization (IVF) and parthenogenetic activation (PA) counterparts. Specifically, results showed that amounts of H3K27ac gradually decreased from the earliest pronuclear stage to 8-cell stage, corresponding to the major embryonic genome activation (EGA), followed by re-acetylation of H3K27 from the morula stage onwards accompanying the first cell lineage specification in IVF embryos. Similar dynamic patterns of H3K27ac signal was observed at all developmental stages of porcine SCNT and PA embryos except for the hatched stage in which amounts of H3K27ac in SCNT and PA embryos was slightly less than that in IVF counterparts. Moreover, the gradual decrease of H3K27ac before EGA was demonstrated to be an active process independent of DNA replication, RNA and protein synthesis. The expression of HDAC1, HDAC2, MBD3 and CBP genes were well correlated with the dynamic changes of H3K27ac mark. Overall, these results indicate that H3K27ac is only defective in late SCNT blastocysts, and that the dynamic changes of this marker might also underlie the EGA and initial cell lineage specification during early embryo development.

Effect of red light on the development and quality of mammalian embryos.

To assess irradiance and total energy dose from different microscopes during the in-vitro embryonic developmental cycle in mouse and pig and to evaluate its effect on embryonic development and quality in pig. Spectral scalar irradiance (380-1050 nm) was measured by a fiber-optic microsensor in the focal plane of a dissection microscope, an inverted microscope and a time-lapse incubation system. Furthermore, the effect of three different red light levels was tested in the time-lapse system on mouse zygotes for 5 days, and on porcine zona-intact and zona-free parthenogenetically activated (PA) embryos for 6 days. The time-lapse system used red light centered at 625 nm and with a lower irradiance level as compared to the white light irradiance levels on the dissection and inverted microscopes, which included more energetic radiation <550 nm. Even after 1000 times higher total energy dose of red light exposure in the time-lapse system, no significant difference was found neither in blastocyst development of mouse zygotes nor in blastocyst rates and total cell number of blastocysts of porcine PA embryos. Our results indicate that red light (625 nm, 0.34 W/m(2)) used in the time-lapse incubation system does not decrease the development and quality of blastocysts in both mouse zygotes and porcine PA embryos (both zona-intact and zona-free).

Phosphorylated H2AX in parthenogenetically activated, in vitro fertilized and cloned bovine embryos.

In vitro embryo production methods induce DNA damage in the embryos. In response to these injuries, histone H2AX is phosphorylated (γH2AX) and forms foci at the sites of DNA breaks to recruit repair proteins. In this work, we quantified the DNA damage in bovine embryos undergoing parthenogenetic activation (PA), in vitro fertilization (IVF) or somatic cell nuclear transfer (SCNT) by measuring γH2AX accumulation at different developmental stages: 1-cell, 2-cell and blastocyst. At the 1-cell stage, IVF embryos exhibited a greater number of γH2AX foci (606.1 ± 103.2) and greater area of γH2AX staining (12923.6 ± 3214.1) than did PA and SCNT embryos. No differences at the 2-cell stage were observed among embryo types. Although PA, IVF and SCNT were associated with different blastocyst formation rates (31.1%, 19.7% and 8.3%, P < 0.05), no differences in the number of γH2AX foci or area were detected among the treatments. γH2AX is detected in bovine preimplantation embryos produced by PA, IVF and SCNT; the amount of DNA damage was comparable among those embryos developing to the blastocyst stage among different methods for in vitro embryo production. While IVF resulted in increased damage at the 1-cell embryo stage, no difference was observed between PA and SCNT embryos at any developmental stage. The decrease in the number of double-stranded breaks at the blastocyst stage seems to indicate that DNA repair mechanisms are functional during embryo development.

Characterization of the Altered Gene Expression Profile in Early Porcine Embryos Generated from Parthenogenesis and Somatic Cell Chromatin Transfer

The in vitro production of early porcine embryos is of particular scientific and economic interest. In general, embryos produced from in vitro Assisted Reproductive Technologies (ART) manipulations, such as somatic cell chromatin transfer (CT) and parthenogenetic activation (PA), are less developmentally competent than in vivo–derived embryos. The mechanisms underlying the deficiencies of embryos generated from PA and CT have not been completely understood. To characterize the altered genes and gene networks in embryos generated from CT and PA, comparative transcriptomic analyses of in vivo (IVV) expanded blastocysts (XB), IVV hatched blastocyst (HB), PA XB, PA HB, and CT HB were performed using a custom microarray platform enriched for genes expressed during early embryonic development. Differential expressions of 1492 and 103 genes were identified in PA and CT HB, respectively, in comparison with IVV HB. The “eIF2 signalling”, “mitochondrial dysfunction”, “regulation of eIF4 and p70S6K signalling”, “protein ubiquitination”, and “mTOR signalling” pathways were down-regulated in PA HB. Dysregulation of notch signalling–associated genes were observed in both PA and CT HB. TP53 was predicted to be activated in both PA and CT HB, as 136 and 23 regulation targets of TP53 showed significant differential expression in PA and CT HB, respectively, in comparison with IVV HB. In addition, dysregulations of several critical pluripotency, trophoblast development, and implantation-associated genes (NANOG, GATA2, KRT8, LGMN, and DPP4) were observed in PA HB during the blastocyst hatching process. The critical genes that were observed to be dysregulated in CT and PA embryos could be indicative of underlying developmental deficiencies of embryos produced from these technologies.