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

Ellagic acid treatment during in vitro maturation of porcine oocytes improves development competence after parthenogenetic activation and somatic cell nuclear transfer

Ellagic acid (EA) is a natural polyphenol and a free radical scavenger with antioxidant properties. This study investigated the protective effects of EA during in vitro maturation (IVM) of porcine oocytes. To determine the optimal concentration, IVM medium was supplemented with various concentrations of EA. Treatment with 10 μM EA (10 EA) resulted in the highest cleavage rate, blastocyst formation rate, and total cell number per blastocyst and the lowest percentage of apoptotic cell in parthenogenetic blastocysts. In the 10 EA group, abnormal spindle and chromosome misalignment were rescued and the ratio of phosphorylated p44/42 to total p44/42 was increased. Furthermore, the reactive oxygen species and glutathione levels were significantly decreased and increased, respectively, and antioxidant genes (Nrf2, HO-1, CAT, and SOD1) were significantly upregulated in the 10 EA group. mRNA expression of developmental-related (CDX2, POU5F1, and SOX2) and anti-apoptotic (BCL2L1) genes was significantly upregulated in the 10 EA group, while mRNA expression of pro-apoptotic genes (BAK, FAS, and CASP3) was significantly downregulated. Ultimately, following somatic cell nuclear transfer, the blastocyst formation rate was significantly increased and the percentage of apoptotic cell in blastocysts was significantly decreased in the 10 EA group. In conclusion, addition of 10 EA to IVM medium improved oocyte maturation and the subsequent embryo development capacity through antioxidant mechanisms. These findings suggest that EA can enhance the efficiencies of assisted reproductive technologies.

Chrysoeriol Improves the Early Development Potential of Porcine Oocytes by Maintaining Lipid Homeostasis and Improving Mitochondrial Function

Our previous study established that chrysoeriol (CHE) can reduce reactive oxygen species (ROS) accumulation, apoptosis, and autophagy in vitro culture (IVC) of porcine embryos. However, the role of CHE in oocyte maturation and lipid homeostasis is unclear. Herein, we aimed to elucidate the effect of CHE on porcine oocyte competence in vitro maturation (IVM) and subsequent embryo development. The study chooses parthenogenetic activated porcine oocytes as the research model. The study revealed that the cumulus expansion index and related gene expressions are significantly elevated after supplementing 1 μM CHE. Although there were no significant differences in nuclear maturation and cleavage rates, the blastocyst formation rate and total cell numbers were significantly increased in the 1 μM CHE group. In addition, CHE improved the expression of genes related to oocyte and embryo development. ROS was significantly downregulated in all CHE treatment groups, and intracellular GSH (glutathione) was significantly upregulated in 0.01, 0.1, and 1 μM CHE groups. The immunofluorescence results indicated that mitochondrial membrane potential (MMP) and lipid droplet (LD), fatty acid (FA), ATP, and functional mitochondria contents significantly increased with 1 μM CHE compared to the control. Furthermore, CHE increased the expression of genes related to lipid metabolism, mitochondrial biogenesis, and β-oxidation.

Effect of putrescine supplementation to in vitro maturation medium on embryo development and quality in cattle

This study aimed to investigate the effect of putrescine supplementation to maturation medium during in vitro embryo production in cattle on maturation and embryo development/quality. Oocytes obtained from the ovaries of Holstein cattle were used in the study. Obtained cumulus-oocyte complexes were evaluated according to morphological structure, cytoplasmic features, and cumulus cell number, and only Category-I ones were used in the study. Before the in vitro maturation step, oocytes were randomly divided into two groups. In the first group (Putrescine group, n = 159), 0.5 mM putrescine was added to the maturation medium before in vitro maturation. No addition was applied to the maturation medium of the second group (Control group, n = 149). Cumulus expansion degrees of oocytes following maturation (Grade I: poor, Grade II: partial, and Grade III: complete) were determined. In addition, the meiosis of oocytes after maturation was evaluated by differential staining. Then the oocytes were left for fertilization with sperm and finally, possible zygotes were transferred to the culture medium. After determining the developmental stages and quality of the embryos after in vitro culture, only the embryos at the blastocyst stage were stained with the differential staining method to determine the cell numbers. When the cumulus expansion degrees of the groups were evaluated, the Grade III cumulus expansion rate in the putrescine group was higher than the control group (74.21% and 60.4%; respectively) and the Grade I expansion rate (11.95% and 26.17%; respectively) was found lower (p < .05). When the resumption of meiosis was evaluated according to the cumulus expansion degrees, it was determined that the rate of resumption of meiosis increased as the cumulus expansion increased. In addition, the cleavage rates of oocytes and reaching the blastocyst in the putrescine group were found to be higher than in the control group (p < .05). Moreover, inner cell mass, trophectoderm cells, and total cell counts were found to be higher in blastocysts obtained after the putrescine supplementation to the maturation medium compared to the control group (p < .05). As a result, it was determined that the putrescine supplementation to the maturation medium during in vitro embryo production in cattle increased the degree of cumulus expansion and the rate of resumption of meiosis. In addition, putrescine supplementation was thought to increase the rate of reaching the blastocyst of oocytes due to better cell development in embryos.

Tannin Reduces the Incidence of Polyspermic Penetration in Porcine Oocytes

Tannin (TA) improves porcine oocyte cytoplasmic maturation and subsequent embryonic development after in vitro fertilization (IVF). However, the mechanism through which TA blocks polyspermy after IVF remains unclear. Hence, the biological function of organelles (cortical granule [CG], Golgi apparatus, endoplasmic reticulum [ER], and mitochondria) and the incidence of polyspermic penetration were examined. We found no significant difference in oocyte nuclear maturation among the 1 µg/mL, 10 µg/mL TA, and control groups. Moreover, 100 μg/mL TA significantly reduced 1st polar body formation rate compared to the other groups. Additionally, 1 and 10 μg/mL TA significantly increased the protein levels of GDF9, BMP15, and CDK1 compared to the control and 100 μg/mL TA groups. Interestingly, 1 and 10 μg/mL TA improved the normal distribution of CGs, Golgi, ER, and mitochondria by upregulating organelle-related gene expression and downregulating ER stress (CHOP) gene expression. Simultaneously, 1 and 10 μg/mL TA significantly increased the proportion of normal fertilized oocytes (2 pronuclei; 2 PN) and blastocyst formation rate compared to the control, as well as that of 100 μg/mL TA after IVF by upregulating polyspermy-related genes. In conclusion, TA during IVM enhances 2PN and blastocyst formation rates by regulating organelles’ functions and activities.

Ramelteon Reduces Oxidative Stress by Maintenance of Lipid Homeostasis in Porcine Oocytes

This study aimed to determine the underlying mechanism of ramelteon on the competence of oocyte and subsequent embryo development in pigs during in vitro maturation (IVM). Our results showed that the cumulus expansion index was significantly lower in the control group compared to the ramelteon groups (p < 0.05). Moreover, supplementation of 10−11 and 10−9 M ramelteon significantly increased the cumulus expansion and development-related genes expression, and reduced apoptosis in cumulus cells (p < 0.05). In oocytes, the nuclear maturation rate was significantly improved in 10−11, 10−9, and 10−7 M ramelteon groups compared to the control (p < 0.05). Additionally, the level of intracellular GSH was significantly increased and ROS was significantly decreased in ramelteon-supplemented groups, and the gene expression of oocyte development and apoptosis were significantly up- and down-regulated by 10−11 and 10−9 M ramelteon (p < 0.05), respectively. The immunofluorescence results showed that the protein levels of GDF9, BMP15, SOD1, CDK1, and PGC1α were significantly increased by 10−11 M ramelteon compared to the control (p < 0.05). Although there was no significant difference in cleavage rate, the blastocyst formation rate, total cell numbers, and hatching/-ed rate were significantly improved in 10−11 M ramelteon group compared to the control (p < 0.05). Furthermore, embryo development, hatching, and mitochondrial biogenesis-related genes were dramatically up-regulated by 10−11 M ramelteon (p < 0.05). In addition, the activities of lipogenesis and lipolysis in oocytes were dramatically increased by 10−11 M ramelteon compared to the control (p < 0.05). In conclusion, supplementation of 10−11 M ramelteon during IVM improved the oocyte maturation and subsequent embryo development by reducing oxidative stress and maintenance of lipid homeostasis.

Microbial and metabolomic mechanisms mediating the effects of dietary inulin and cellulose supplementation on porcine oocyte and uterine development

Background

Dietary fiber (DF) is often eschewed in swine diet due to its anti-nutritional effects, but DF is attracting growing attention for its reproductive benefits. The objective of this study was to investigate the effects of DF intake level on oocyte maturation and uterine development, to determine the optimal DF intake for gilts, and gain microbial and metabolomic insight into the underlying mechanisms involved.

Methods

Seventy-six Landrace × Yorkshire (LY) crossbred replacement gilts of similar age (92.6 ± 0.6 d; mean ± standard deviation [SD]) and body weight (BW, 33.8 ± 3.9 kg; mean ± SD) were randomly allocated to 4 dietary treatment groups (n = 19); a basal diet without extra DF intake (DF 1.0), and 3 dietary groups ingesting an extra 50% (DF 1.5), 75% (DF 1.75), and 100% (DF 2.0) dietary fiber mixture consisting of inulin and cellulose (1:4). Oocyte maturation and uterine development were assessed on 19 d of the 2nd oestrous cycle. Microbial diversity of faecal samples was analysed by high-throughput pyrosequencing (16S rRNA) and blood samples were subjected to untargeted metabolomics.

Results

The rates of oocytes showing first polar bodies after in vitro maturation for 44 h and uterine development increased linearly with increasing DF intake; DF 1.75 gilts had a 19.8% faster oocyte maturation rate and a 48.9 cm longer uterus than DF 1.0 gilts (P <  0.05). Among the top 10 microbiota components at the phylum level, 8 increased linearly with increasing DF level, and the relative abundance of 30 of 53 microbiota components at the genus level (> 0.1%) increased linearly or quadratically with increasing DF intake. Untargeted metabolic analysis revealed significant changes in serum metabolites that were closely associated with microbiota, including serotonin, a gut-derived signal that stimulates oocyte maturation.

Conclusions

The findings provide evidence of the benefits of increased DF intake by supplementing inulin and cellulose on oocyte maturation and uterine development in gilts, and new microbial and metabolomic insight into the mechanisms mediating the effects of DF on reproductive performance of replacement gilts.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-021-00657-0.

Idebenone relieves the damage of heat stress on the maturation and developmental competence of porcine oocytes

The reproductive function of animals is often affected by climatic conditions. High-temperature conditions can cause damage to oocyte maturation and embryonic development in a variety of ways. The purpose of this study was to prove that supplementation idebenone (IDB) to the maturation medium can improve the maturation and development of porcine oocytes after heat stress (HS). Porcine cumulus-oocyte complexes (COCs) were cultured in the maturation medium with different concentrations of IDB (0, 0.1, 1 and 10 μM) for 44 hr at either 38.5°C or under the HS conditions. The cumulus oophorus expansion, nuclear maturation and blastocyst rate after parthenogenetic activation (PA) were measured. We found that HS (in vitro maturation 20-24 hr, 42°C) exposure significantly reduced cumulus expansion index and maturation rate of oocytes and the blastocyst rate of PA embryos, while IDB supplementation significantly improved oocyte maturation and development to the blastocysts stage after PA. Moreover, the addition of IDB decreased the intracellular level of ROS and increased GSH content, hence enhancing the antioxidant capacity of oocytes under HS. Meanwhile, IDB treatment also obviously improved the mitochondrial membrane potential and ATP synthesis of oocytes under HS conditions. Furthermore, IDB treatment increased the expression of GDF9 and BMP15 in IVM oocytes which attribute to improve the quality and outcome of IVM oocytes and the development competence of PA embryos in pigs. In summary, we demonstrated that IDB supplementation into the maturation medium exerted protective effects and improved the ability of maturation and developmental competence of porcine oocytes exposed to HS.

In vitro maturation using αMEM containing reduced NaCl enhances maturation and developmental competence of pig oocytes after somatic cell nuclear transfer

Background

Compared to medium containing 108 mM sodium chloride (NaCl), in vitro maturation (IVM) using a simple medium with reduced (61.6 mM) NaCl increases the cytoplasmic maturation and embryonic development of pig oocytes.

Objectives

This study determines the effect of a complex medium containing reduced NaCl on the IVM and embryonic development of pig oocytes.

Methods

Pig oocytes were matured in Minimum Essential Medium Eagle-alpha modification (αMEM) supplemented with 61.6 (61αMEM) or 108 (108αMEM) mM NaCl, and containing polyvinyl alcohol (PVA) (αMEMP) or pig follicular fluid (PFF) (αMEMF). Medium-199 (M199) served as the control for conventional IVM. Cumulus cell expansion, nuclear maturation, intra-oocyte glutathione (GSH) contents, size of perivitelline space (PVS), and embryonic development after parthenogenesis (PA) and somatic cell nuclear transfer (SCNT) were evaluated after IVM.

Results

Regardless of PVA or PFF supplementation, oocytes matured in 61αMEM showed increased intra-oocyte GSH contents and width of PVS (p < 0.05), as well as increased blastocyst formation (p < 0.05) after PA and SCNT, as compared to oocytes matured in 108αMEMP and M199. Under conditions of PFF-enriched αMEM, SCNT oocytes matured in 61αMEMF showed higher blastocyst formation (p < 0.05), compared to maturation in 108αMEMF and M199, whereas PA cultured oocytes showed no significant difference.

Conclusions

IVM in αMEM supplemented with reduced NaCl (61.6 mM) enhances the embryonic developmental competence subsequent to PA and SCNT, which attributes toward improved oocyte maturation.

The Use of κ-Carrageenan in Egg Yolk Free Extender Improves the Efficiency of Canine Semen Cryopreservation

κ-Carrageenan is a plant polysaccharide derived from red seaweeds reported to possess potential medicinal and antioxidants activities. The present study aimed to identify the cryoprotective effects of κ-carrageenan on the quality of frozen-thawed canine semen. Twenty-eight ejaculates were collected and diluted in a Tris egg-yolk-free extender supplemented with various concentrations of κ-carrageenan (0.0%, 0.1%, 0.2%, 0.3%, and 0.5%). The addition of κ-carrageenan to the extender at a 0.2% concentration induced a significant increase in the total motility (TM) and the rapid progressive motility (RPM) of canine sperm. Among the experimental groups, the highest percentage of sperms with intact acrosomes was found in the 0.5% κ-carrageenan group (p < 0.05). Apoptosis levels were significantly lower in the 0.1% and 0.2% κ-carrageenan treatment. Moreover, sperm in the κ-carrageenan supplemented group showed a significantly higher expression of antiapoptotic (Bcl-2) and lower expression of NADPH oxidase (NOX5), spermine synthase (SMS), and spermine oxidase (SMOX) genes than those in the control group. In conclusion, the addition of κ-carrageenan to the freezing extender improved the overall efficiency of frozen-thawed dog spermatozoa.

Redox Regulation and Oxidative Stress in Mammalian Oocytes and Embryos Developed In Vivo and In Vitro

Oocytes and preimplantation embryos require careful regulation of the redox environment for optimal development both in vivo and in vitro. Reactive oxygen species (ROS) are generated throughout development as a result of cellular metabolism and enzyme reactions. ROS production can result in (i) oxidative eustress, where ROS are helpful signalling molecules with beneficial physiological functions and where the redox state of the cell is maintained within homeostatic range by a closely coupled system of antioxidants and antioxidant enzymes, or (ii) oxidative distress, where excess ROS are deleterious and impair normal cellular function. in vitro culture of embryos exacerbates ROS production due to a range of issues including culture-medium composition and laboratory culture conditions. This increase in ROS can be detrimental not only to assisted reproductive success rates but can also result in epigenetic and genetic changes in the embryo, resulting in transgenerational effects. This review examines the effects of oxidative stress in the oocyte and preimplantation embryo in both the in vivo and in vitro environment, identifies mechanisms responsible for oxidative stress in the oocyte/embryo in culture and approaches to reduce these problems, and briefly examines the potential impacts on future generations.

Tannin Supplementation Improves Oocyte Cytoplasmic Maturation and Subsequent Embryo Development in Pigs

To investigate the effects of tannins (TA) on porcine oocyte in vitro maturation (IVM), different concentrations of TA (0, 1, 10 and 100 μg/mL) were supplemented with a maturation medium and the COCs and subsequent embryonic development were examined. The results showed that 10 µg/mL TA significantly improved the cumulus expansion index (CEI), cumulus-expansion-related genes (PTGS1, PTGS2, PTX-3, TNFAIP6 and HAS2) expression and blastocyst formation rates after parthenogenetic activation (PA), in vitro fertilization (IVF) and somatic cell nuclear transfer (SCNT) compared to the control groups, but not oocyte nuclear maturation. Nevertheless, 10 µg/mL TA dramatically enhanced the mRNA expression of oocyte-development-related genes (BMP15, GDF9, CDC2 and CYCLIN B1), GSH, ATP, SOD1, PGC1α, BMP15, GDF9 and CDC2 levels and reduced intracellular ROS level in porcine oocytes. These results indicated that porcine oocyte cytoplasmic maturation was improved by 10 µg/mL TA treatment during IVM. In contrast, a high concentration of TA (100 μg/mL) significantly decreased the CEI and PTGS1, PTGS2, PTX-3 and HAS2 mRNA expressions in cumulus cells, and reduced oocyte nuclear maturation and the total cell numbers/blastocyst. In general, these data showed that 10 μg/mL TA supplementation has beneficial effects on oocyte cytoplasmic maturation and subsequent embryonic development in pigs.

Adiponectin Improves In Vitro Development of Cloned Porcine Embryos by Reducing Endoplasmic Reticulum Stress and Apoptosis

Simple Summary

Successful attenuation of endoplasmic reticulum (ER) stress signaling has a beneficial outcome in in vitro embryonal improvement. We evaluated the effect of adiponectin during in vitro culture in porcine embryos derived from parthenogenetic activation and somatic cell nuclear transfer (SCNT). We found that 15 and 30 μg/mL adiponectin treatment significantly improved cleavage rates, blastocyst formation rates, and total cell number (TCN) of blastocysts derived from parthenogenetic activation and reduced the expression levels of XBP1. In SCNT embryos, the cleavage rate, blastocyst formation rate, and TCN of blastocysts were significantly improved by 15 μg/mL adiponectin treatment compared to the control. In addition, the 15 μg/mL adiponectin treatment reduced the levels of XBP1 expression and ER stress-related genes, increased expression levels of pluripotency-related genes, and decreased apoptosis-related gene expression. Comprehensively, treatment with 15 μg/mL adiponectin enhanced the in vitro developmental capacity of early-stage SCNT porcine embryos by reducing ER stress and apoptosis.

Abstract

The main factor of embryonic demise is endoplasmic reticulum (ER) stress. Successful attenuation of ER stress results in an improvement in embryo development. We studied the impact of adiponectin in the in vitro culture (IVC) of porcine embryos derived from parthenogenetic activation and somatic cell nuclear transfer (SCNT). The first experiment revealed that 15 and 30 μg/mL adiponectin treatments improved cleavage, blastocyst rates, and total cell number (TCN) of parthenogenetic embryos and reduced the expression of XBP1 compared to the 5 μg/mL adiponectin treatment and control groups (p < 0.05). The second experiment showed that cleavage rate, blastocyst formation rate, and TCN of blastocysts were improved in the 15 μg/mL adiponectin treatment group compared with the control group, with significantly reduced XBP1 expression in ≥4-cell stage SCNT embryos and blastocysts (p < 0.05). Treatment with 15 μg/mL adiponectin significantly improved the expression of XBP1 and reduced the expression of ER stress-related genes (uXBP1, sXBP1, PTPN1, and ATF4), increased the expression levels of pluripotency-related genes (Nanog and SOX2), and decreased apoptosis-related gene expression (Caspase-3). These results suggest that 15 μg/mL adiponectin enhanced the in vitro developmental capacity of early-stage SCNT porcine embryos by reducing ER stress and apoptosis.

Effect of Klotho protein during porcine oocyte maturation via Wnt signaling

Klotho protein is well-known as an anti-aging agent, however, several studies have suggested that Klotho protein also increases antioxidant activity and the reproductive system, as Klotho protein is closely associated with Wnt signaling. The objective of our study was to investigate the enhancement of porcine oocyte in vitro maturation via the Klotho protein-Wnt signaling pathway. Following immunohistochemistry and ELISA, we treated cells with Klotho protein during in vitro maturation. Lithium Chloride, a specific activator of Wnt signaling, was subsequently co-administered with Klotho protein. Mature oocytes subjected to treatments were used for the analysis of embryonic development, qRT-PCR, and immunocytochemistry. Treatment with 5pg/ml Klotho protein significantly increased cumulus cell expansion, blastocyst formation rates, and the total cell number of blastocysts. During cotreatment with 5mM Lithium Chloride and 5pg/ml Klotho protein, blastocyst formation rates were the highest in Klotho protein-treated oocytes and the lowest in Lithium Chloride-treated oocytes. Expression levels of Wnt signaling-related transcripts and proteins were significantly impacted by Klotho protein and Lithium Chloride. Moreover, cellular ATP levels and antioxidant activities were enhanced by Klotho protein treatment. These findings suggest a significant involvement of the Klotho protein-Wnt signaling mechanism in porcine oocyte maturation.

Melatonin-Nrf2 Signaling Activates Peroxisomal Activities in Porcine Cumulus Cell-Oocyte Complexes

Melatonin and Nrf2 signaling synergistically improve mammalian oocyte maturation and embryonic development. Furthermore, previous studies have suggested an interplay between peroxisomes and Nrf2 signaling in cells, but it is still unclear whether peroxisomes are involved in oocyte maturation. The aim of the present study was to identify the possible roles of peroxisomes in the melatonin-Nrf2 signaling pathway during in vitro maturation (IVM) of porcine oocytes. Porcine oocytes were treated with melatonin (10^-9 M) and brusatol, a Nrf2 specific inhibitor, in order to investigate the mechanism. Then, the rates of maturation and related gene and protein expression were analyzed. During oocyte maturation, melatonin upregulated the expression of gene and protein related to Nrf2 signaling and peroxisomal activities; RNA sequencing partially validated these results. Our results demonstrate that melatonin can activate Nrf2 signaling by binding to melatonin receptor 2, resulting in the upregulation of catalase. Moreover, peroxisomes were also found to be activated in response to melatonin treatment, causing the activation of catalase; together with Nrf2 signaling, peroxisomes synergistically prevented the generation of reactive oxygen species and enhanced oocyte quality. Thus, we suggest that a crosstalk might exist between Nrf2 signaling and peroxisomal activities in porcine oocytes.

Effect of Rhodiola sachalinensis Aqueous Extract on In Vitro Maturation of Porcine Oocytes and Subsequent In Vitro Embryonic Development

Oxidative stress can impede maturation of the nucleus and cytoplasm of oocytes during in vitro maturation (IVM). Rhodiola sachalinensis, an herb commonly used in traditional Chinese medicine, conveys antioxidative effects to cryopreserved bovine sperm. Therefore, the aims of this study were to evaluate the effects of different concentrations of R. sachalinensis aqueous extract (RSAE) on IVM and subsequent in vitro embryonic development after parthenogenetic activation (PA), in vitro fertilization (IVF), and somatic cell nuclear transfer (SCNT). The results showed that RSAE supplementation (6 and 60 mg/L) significantly increased intracellular glutathione levels, but had no effect on maturation rates or reactive oxygen species. After in vitro culture, greater blastocyst formation was observed in PA embryos (6 mg/L RSAE), as well as in IVF and SCNT embryos (60 mg/L) matured in RSAE-supplemented IVM media. In conclusion, although there was no significant improvement in the maturation rate, RSAE supplementation conveyed an antioxidative effect during IVM, and improved subsequent embryonic development in vitro. Further studies are needed to explore gene expression pattern in oocytes and embryos treated with RSAE.

Zinc supplementation alleviates endoplasmic reticulum stress during porcine oocyte in vitro maturation by upregulating zinc transporters

Endoplasmic reticulum (ER) stress is a major contributor to embryonic development failure. Mammalian oocytes have a high risk of exposure to cellular stress during in vitro embryo production. We investigated the effects of zinc supplementation during in vitro maturation under ER stress. We evaluated cumulus expansion, embryonic development derived by parthenogenetic activation, reactive oxygen species, protein expression of X-box binding protein 1 (XBP1), and expression of genes related to ER stress. Supplementation with 1 μg/ml zinc significantly increased the nuclear maturation of oocytes, cleavage and blastocyst formation rates, and total blastocyst cell number (p < .05). Under ER stress, zinc significantly reduced protein expression of XBP1, and increased cleavage and blastocyst rates (p < .05). Concomitantly, zinc supplementation upregulated the expression of zinc transporters (SLC39A14 and SLC39A10), PTGS2, and downregulated ER stress-related genes (sXBP1, uXBP1, ATF4, and PTPN1/PTP1B), and caspase 3. These results suggest that zinc supplementation alleviates ER stress by providing essential metal-ion transporters for oocyte maturation and subsequent embryonic development.

Use of black seed (Nigella sativa) honey bee to improve sheep oocyte maturation medium

Sheep are important livestock and a source of milk, meat, and wool globally. The increasing demand for animal protein requires increased productivity in sheep. In vitro fertilization and maturation can improve sheep productivity. The aims of this study were to evaluate the effects of honey bee addition as a supplementation medium on in vitro maturation improvement, gene expression of matured sheep oocytes, and determine the optimum concentration from honey bee for in vitro maturation of sheep oocytes. Cumulus oocyte complexes were obtained from the ovaries of slaughtered female sheep. Grade A and B oocytes were cultured for 24 h in medium without honey bee (control, G1) or medium supplemented with 5% (G2), 10% (G3), or 20% (G4) honey bee. Oocyte maturation rate, glutathione concentration, and the expression of candidate genes (GDF-9, BAX, Cyclin B, C-MOS, IGF1) were determined in the matured oocytes. The maturation rate of sheep oocyte was better in the presence of 5% and 10% honey bee; the mean number of oocytes in metaphase II stage was higher than that in G1 and G4 groups. Glutathione concentration was highest in G2 (10.93 ± 0.57). In general, gene expression levels were similar in G2 and G3, which were greater that in G1 and G4. In conclusion, the optimal concentration of black seeds honey bee that can be added to the maturation medium is 5% to obtain the highest mean MII and glutathione concentration values, and to improve gene expression in in vitro matured sheep oocytes.

Baicalin improves IVM of pig oocytes and subsequent preimplantation embryo development by inhibiting apoptosis

Baicalin, a monomer of flavonoids extracted from dried roots of Scutellaria baicalensis, is used to treat female infertility. However, the effect of baicalin on oocyte maturation is unknown. In this study we investigated the effects of baicalin on the IVM of pig oocytes and subsequent embryo development following parthenogenetic activation (PA). We found that 0.1µgmL-1 baicalin significantly (P<0.05) increased the IVM rate of oocytes compared with the non-treatment (control) group by reducing levels of reactive oxygen species (ROS). In addition, the mRNA expression of genes related to nuclear maturation and cumulus cell expansion, mitochondrial membrane potential and ATP content was significantly (P<0.05) higher in baicalin-treated than control oocytes. To determine whether baicalin treatment during IVM of pig oocytes improves subsequent development of PA embryos, we measured the cleavage and blastocyst formation rates, as well as the number of cells per blastocyst. All these parameters were significantly (P<0.05) higher in the baicalin-treated than control group. In conclusion, this study demonstrates that baicalin improves pig oocyte maturation and subsequent embryo development invitro by inhibiting production of ROS and reducing apoptosis in oocytes.

Sphingosine-1-phosphate (S1P) analog phytosphingosine-1-phosphate (P1P) improves the in vitro maturation efficiency of porcine oocytes via regulation of oxidative stress and apoptosis

Phytosphingosine-1-phosphate (P1P) is a signaling sphingolipid that regulates various physiological activities. However, little is known about the effect of P1P in the context of reproduction. Thus, we aimed to investigate the influence of P1P on oocyte maturation during porcine in vitro maturation (IVM). Here, we report the expression of S1PR1-3 among P1P receptors (S1PR1-4) in cumulus cells and oocytes. When P1P was administered at concentrations of 10, 50, 100, and 1,000 nM during IVM, the metaphase II rate was significantly increased in the 1,000 nM (1 μM) P1P treatment group. Maturation rate improvement by P1P supplementation was observed only in the presence of epidermal growth factor (EGF). Oocytes under the influence of P1P showed decreased intracellular reactive oxygen species levels but no significant differences in glutathione levels. In our molecular studies, P1P treatment upregulated gene expression involved in cumulus expansion (Has2 and EGF), antioxidant enzymes (SOD3 and Cat), and developmental competence (Oct4) while activating extracellular signal-regulated kinase1/2 and Akt signaling. P1P treatment also influenced oocyte survival by shifting the ratio of Bcl-2 to Bax while inactivating JNK signaling. We further demonstrated that oocytes matured with P1P displayed significantly higher developmental competence (cleavage and blastocyst [BL] formation rate) and greater BL quality (total cell number and the ratio of apoptotic cells) when activated via parthenogenetic activation (PA) and in vitro fertilization. Despite the low levels of endogenous P1P found in animals, exogenous P1P influenced animal reproduction, as shown by increased porcine oocyte maturation as well as preimplantation embryo development. This study and its findings are potentially relevant for both human and animal-assisted reproduction.

Effects of manganese on maturation of porcine oocytes in vitro and their subsequent embryo development after parthenogenetic activation and somatic cell nuclear transfer

This study was carried out to examine the effects of manganese (Mn) on the developmental competence of porcine oocytes during in vitro maturation (IVM) after parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT). Upon treatment of porcine oocytes with different concentrations (0, 3, 6, and 12 ng/ml) of Mn during IVM, PA was performed to determine the optimum concentration. Following PA, the rate of blastocyst formation was higher significantly in treated porcine oocytes at 6 ng/ml of Mn than in other groups (P < 0.05). However, there was no substantial difference in the cleavage rate and total blastocyst cell numbers among all groups. SCNT was performed using the optimal concentration of Mn from PA, which showed an improved blastocyst formation rate in treated oocytes compared to that in control group (P < 0.05). However, the cleavage rate and total cell numbers per blastocyst were not different between the control and the Mn treated groups after SCNT. Additionally, oocyte nuclear maturation, intracellular glutathione (GSH), and reactive oxygen species (ROS) levels were assessed. There was no significant difference observed in nuclear maturation among all the groups. However, enhanced intracellular GSH levels while lower levels of ROS were seen in the Mn treated group compared to the control group (P < 0.05). Thus, these results indicate that Mn supplementation can improve the developmental competence of porcine PA and SCNT embryos by increasing GSH and decreasing ROS levels.

Iodixanol supplementation during sperm cryopreservation improves protamine level and reduces reactive oxygen species of canine sperm

The objective of this study was to analyze the protective effects of iodixanol on dog spermatozoa during cryopreservation. The optimal concentration of iodixanol, 1.5%, was determined using fresh spermatozoa and was applied in the following experiments. The 1.5% iodixanol group showed significantly increased sperm motility from that in the control (p < 0.05). Lower mitochondrial reactive oxygen species (ROS) modulator (ROMO1) and pro-apoptotic gene (BAX) expressions, together with higher expressions of protamine-2 (PRM2), protamine-3 (PRM3), anti-apoptotic B-cell lymphoma-2 (BCL2), and sperm acrosome associated-3 (SPACA3) genes were detected in the iodixanol-treated group. In addition, decreased protamine deficiency and cryocapacitation were observed in the treatment group. Our results show that supplementation with 1.5% iodixanol is ideal for reducing production of ROS and preventing detrimental effects during the canine sperm cryopreservation process, effects manifested as increased motility and reduced cryocapacitation in frozen-thawed spermatozoa.

Oocyte maturation with royal jelly increases embryo development and reduces apoptosis in goats

Royal jelly (RJ) was supplemented to goat oocyte in vitro maturation (IVM) medium at three different concentrations (2.5, 5, and 10 mg/ml). Maturation rate, embryo cleavage, and blastocyst rate were recorded. Gene expression of apoptosis-related transcripts was investigated in matured oocytes. Percentage of oocytes that reached MII-stage was increased in RJ-treated groups compared to the control group. Glutathione (GSH) content of mature oocytes was enhanced when RJ was added to IVM medium at any supplementation compared with control. Percentage of cleaved embryos and blastocysts was higher in the RJ-treated groups at a concentration of 5 than in the 2.5 mg/ml and control group. Total number of cells per blastocyst was not different in the control and RJ-treated group at 5 mg/ml. However, number of apoptotic cells per blastocyst was higher in the control group than in the RJ-treated group at 5 mg/ml. Expression profile of Bax, and p53 was down-regulated while Bcl-2 was up-regulated in oocytes treated with RJ at 5 and 10 mg/ml compared with the control group. Addition of RJ at concentrations of 5 mg/ml improved embryo production through increasing maturation rate. RJ seems to improve the IVM microenvironment by reducing expression of genes inducing apoptosis, enhancing GSH content, and reducing incidence of apoptosis in blastocysts.

Glycine treatment enhances developmental potential of porcine oocytes and early embryos by inhibiting apoptosis

Glycine, a component of glutathione (GSH), plays an important role in protection from reactive oxygen species (ROS) and inhibition of apoptosis. The aim of this study was to determine the effect of glycine on in vitro maturation (IVM) of porcine oocytes and their developmental competence after parthenogenetic activation (PA). We examined nuclear maturation, ROS levels, apoptosis, mitochondrial membrane potential (ΔΨm), and ATP concentration, as well as the expression of several genes related to oocyte maturation and development. Our studies found that treatment with glycine in IVM culture medium increased nuclear maturation rate, but varying the concentrations of glycine (0.6, 6, or 12 mM) had no significant effect. Furthermore, 6 mM glycine supported greater blastocyst formation rates and lesser apoptosis after PA than the other concentrations (P < 0.05). All the glycine treatment groups had decreased levels of ROS in both matured oocytes and at the 2-cell stage (P < 0.05). At the 2-cell stage, the 6 mM glycine group had ROS levels that were lesser than the other 2 glycine treatment groups (0.6 and 12 mM). From this, we deemed 6 mM to be the optimal condition, and we then investigated the effects of 6 mM glycine on gene expression. The expression of both FGFR2 and Hsf1 were greater than the control group in mature oocytes. The glycine treatment group had greater levels of expression of an antiapoptotic gene (Bcl2) in mature oocytes and cumulus cells and lesser levels of expression of a proapoptotic gene (Bax) in PA blastocysts (P < 0.05). In addition, mitochondrial ΔΨm and ATP concentration were increased in 6 mM glycine group compared with the control group. In conclusion, our results suggest that glycine plays an important role in oocyte maturation and later development by reducing ROS levels and increasing mitochondrial function to reduce apoptosis.

A potential role of knockout serum replacement as a porcine follicular fluid substitute for in vitro maturation: Lipid metabolism approach

The use of supplements, such as porcine follicular fluid (pFF), fetal bovine serum and human serum albumin are widely used during in vitro maturation (IVM) in different species but these supplements contain undefined components that cause technical difficulties in standardization and influence the efficiency of IVM. Knockout serum replacement (KSR) is a synthetic protein source, without any undefined growth factors or differentiation-promoting factors. Therefore, it is feasible to use KSR as a defined component for avoiding effects of unknown molecules in an IVM system. In this study, the rates of oocyte maturation and blastocyst formation after parthenogenetic activation (PA), somatic cell nuclear transfer (SCNT) and in vitro fertilization (IVF) were significantly higher in the 5% KSR supplemented group than in the unsupplemented control group and more similar to those of the 10% pFF supplemented group. Moreover, the intensity of GDF9, BMP15, ROS, GSH, BODIPY-LD, BODIPY-FA, and BODIPY-ATP staining showed similar values between 5% KSR and 10% pFF, which have significant difference with control group. Most of the gene expression related to lipid metabolism with both supplements exhibited similar patterns. In conclusion, 5% KSR upregulated lipid metabolism and thereby provides an essential energy source to sustain and improve oocyte quality and subsequent embryo development after PA, SCNT, and IVF. These indications support the idea that KSR used as a defined serum supplement for oocyte IVM might be universally used in other species.

Mineralized deposits in the uterus of a pig without pregnancy loss

Herein, we describe a case of uterine calcification in the uterus of a pig without pregnancy loss. The recipient underwent cloned embryo transfer and Cesarean section for safe delivery of cloned piglets. During the Cesarean section, 4 white, star-like, (2 × 2 × 2) cm, calcified structures were found within the endometrial cavity. Despite dystrophic calcification around the placenta, healthy cloned piglets were produced successfully. To our knowledge, this is the first reported case of dystrophic calcification occurring within the uterus in a pregnant pig.

Significant Down-Regulation of "Biological Adhesion" Genes in Porcine Oocytes after IVM

Proper maturation of the mammalian oocyte is a compound processes determining successful monospermic fertilization, however the number of fully mature porcine oocytes is still unsatisfactory. Since oocytes’ maturation and fertilization involve cellular adhesion and membranous contact, the aim was to investigate cell adhesion ontology group in porcine oocytes. The oocytes were collected from ovaries of 45 pubertal crossbred Landrace gilts and subjected to two BCB tests. After the first test, only granulosa cell-free BCB⁺ oocytes were directly exposed to microarray assays and RT-qPCR (“before IVM” group), or first in vitro matured and then if classified as BCB⁺ passed to molecular analyses (“after IVM” group). As a result, we have discovered substantial down-regulation of genes involved in adhesion processes, such as: organization of actin cytoskeleton, migration, proliferation, differentiation, apoptosis, survival or angiogenesis in porcine oocytes after IVM, compared to oocytes analyzed before IVM. In conclusion, we found that biological adhesion may be recognized as the process involved in porcine oocytes’ successful IVM. Down-regulation of genes included in this ontology group in immature oocytes after IVM points to their unique function in oocyte’s achievement of fully mature stages. Thus, results indicated new molecular markers involved in porcine oocyte IVM, displaying essential roles in biological adhesion processes.

Effect of co-culture canine cumulus and oviduct cells with porcine oocytes during maturation and subsequent embryo development of parthenotes in vitro

In the estrus stage, canine oocytes are surrounded by cumulus cells and undergo maturation in the oviduct for 2-3 days after ovulation. We hypothesized that canine oviduct cells (cOC) and canine cumulus cells (cCC) during this stage might affect the maturation of oocytes and thereby improve subsequent embryo development. Therefore, the objective of this study was to compare the effects of a cOC and cCC co-culture on oocyte in vitro maturation (IVM) and subsequent embryo development, and to analyze the gene expressions in a molecular fashion what co-culture actually gives the specific pathways in which the co-culture cells act to improve maturation and embryo development. The effect of co-culture using cOC and cCC on porcine oocyte IVM was investigated. Thereafter, oocytes were activated using electrical stimulation and embryo developmental competence was estimated. The expression of the genes related to oocyte maturation, embryo development and apoptosis were analyzed. Also, reactive oxygen species (ROS) levels after IVM was analyzed. The IVM rate and embryo development including cleavage, blastocyst formation rates, and total blastocyst cell numbers from cOC group were significantly higher than other groups (P < 0.05). The expression of SMAD2/3 and growth differentiation factor 9 (GDF9) was significantly increased in cOC and oocytes from the cOC group compared with other groups. Moreover, the levels of GDF9, prostaglandin-endoperoxide synthase 2 (PTGS2), WNT3A and matrix metalloproteinase 2 (MMP2) were significantly up-regulated in blastocysts from the cOC group. The concentration of ROS was significantly lower in the supernatant of cOC groups compared with other groups. Also, the expression of BCL2 was significantly increased in porcine cumulus cells and oocytes from cOC group. The present study demonstrated that co-culture with cOC improved in vitro porcine oocyte maturation and subsequent embryo development competence. Also, co-culture with cOC during IVM induces a suitable environment for oocyte maturation by enhancing the mRNA level of SMAD2/3 and GDF9, and for embryo development by elevating the expression level of PTGS2, WNT3A and MMP2. In addition, the decreased ROS level in cOC co-culture could have a beneficial influence on oocyte maturation.

Genes of cellular components of morphogenesis in porcine oocytes before and after IVM

Proper oocyte maturation in mammals produces an oocyte capable of monospermic fertilization and embryo preimplantation. The cumulus-oocyte complexes (COCs), surrounding an oocyte, play a significant role in oocyte maturation. During this process, when the COCs undergo cumulus expansion wherein tightly compact cumulus cells (CCs) form a dispersed structure, permanent biochemical and molecular modifications occur in the maturing oocytes, indicating that the gene expression between immature and mature oocytes differs significantly. This study focuses on the genes responsible for the cellular components of morphogenesis within the developing oocyte. Brilliant cresyl blue (BCB) was used to determine the developmental capability of porcine oocytes. The immature oocytes (GV stage) were compared with matured oocytes (MII stage), using microarray and qRT-PCR analysis to track changes in the genetic expression profile of transcriptome genes. The data showed substantial upregulation of genes influencing oocyte's morphology, cellular migration and adhesion, intracellular communication, as well as plasticity of nervous system. Conversely, downregulation involved genes related to microtubule reorganization, regulation of adhesion, proliferation, migration and cell differentiation processes in oocytes. This suggests that most genes recruited in morphogenesis in porcine oocyte in vitro, may have cellular maturational capability, since they have a higher level of expression before the oocyte's matured form. It shows the process of oocyte maturation and developmental capacity is orchestrated by significant cellular modifications during morphogenesis.

Postneonatal Mortality and Liver Changes in Cloned Pigs Associated with Human Tumor Necrosis Factor Receptor I-Fc and Human Heme Oxygenase-1 Overexpression

Soluble human tumor necrosis factor (shTNFRI-Fc) and human heme oxygenase 1 (hHO-1) are key regulators for protection against oxidative and inflammatory injury for xenotransplantation. Somatic cells with more than 10 copy numbers of shTNFRI-Fc and hHO-1 were employed in somatic cell nuclear transfer to generate cloned pigs, thereby resulting in seven cloned piglets. However, produced piglets were all dead within 24 hours after birth. Obviously, postnatal death with liver apoptosis was reported in the higher copy number of shTNFRI-Fc and hHO-1 piglets. In liver, the transcript levels of ferritin heavy chain, light chain, transferrin, and inducible nitric oxide synthase were significantly highly expressed compared to those of lower copy number of shTNFRI-Fc and hHO-1 piglets (P < 0.05). Also, H₂O₂ contents were increased, and superoxide dismutase was significantly lower in the higher copy number of shTNFRI-Fc and hHO-1 piglets (P < 0.05). These results indicate that TNFRI-Fc and hHO-1 overexpression may apparently induce free iron in the liver and exert oxidative stress by enhancing reactive oxygen species production and block normal postneonatal liver metabolism.

Quisinostat treatment improves histone acetylation and developmental competence of porcine somatic cell nuclear transfer embryos

Abnormal epigenetic modifications are considered a main contributing factor to low cloning efficiency. In the present study, we explored the effects of quisinostat, a novel histone deacetylase inhibitor, on blastocyst formation rate in porcine somatic-cell nuclear transfer (SCNT) embryos, on acetylation of histone H3 lysine 9 (AcH3K9), and on expression of POU5F1 protein and apoptosis-related genes BAX and BCL2. Our results showed that treatment with 10 nM quisinostat for 24 hr significantly improved the development of reconstructed embryos compared to the untreated group (19.0 ± 1.6% vs. 10.2 ± 0.9%; p < 0.05). Quisinostat-treated SCNT embryos also possessed significantly increased AcH3K9 at the pseudo-pronuclear stage (p < 0.05), as well as improved immunostaining intensity for POU5F1 at the blastocyst stage (p < 0.05). While no statistical difference in BAX expression was observed, BCL2 transcript abundance was significantly different in the quisinostat-treated compared to the untreated control group. Of the 457 quisinostat-treated cloned embryos transferred into three surrogates, six fetuses developed from the one sow that became pregnant. These findings suggested that quisinostat can regulate gene expression and epigenetic modification, facilitating nuclear reprogramming, and subsequently improving the developmental competence of pig SCNT embryos and blastocyst quality.

Melatonin regulates lipid metabolism in porcine oocytes

It is being increasingly recognized that the processes of lipogenesis and lipolysis are important for providing an essential energy source during oocyte maturation and embryo development. Recent studies demonstrated that melatonin has a role in lipid metabolism regulation, including lipogenesis, lipolysis, and mitochondrial biogenesis. In this study, we attempted to investigate the effects of melatonin on lipid metabolism during porcine oocyte in vitro maturation. Melatonin treatment significantly enhanced the number of lipid droplets (LDs) and upregulated gene expression related to lipogenesis (ACACA, FASN, PPARγ, and SREBF1). Oocytes treated with melatonin formed smaller LDs and abundantly expressed several genes associated with lipolysis, including ATGL, CGI-58, HSL, and PLIN2. Moreover, melatonin significantly increased the content of fatty acids, mitochondria, and ATP, as indicated by fluorescent staining. Concomitantly, melatonin treatment upregulated gene expression related to fatty acid β-oxidation (CPT1a, CPT1b, CPT2, and ACADS) and mitochondrial biogenesis (PGC-1α, TFAM, and PRDX2). Overall, melatonin treatment not only altered both the morphology and amount of LDs, but also increased the content of fatty acids, mitochondria, and ATP. In addition, melatonin upregulated mRNA expression levels of lipogenesis, lipolysis, β-oxidation, and mitochondrial biogenesis-related genes in porcine oocytes. These results indicated that melatonin promoted lipid metabolism and thereby provided an essential energy source for oocyte maturation and subsequent embryonic development.

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 80 μM) of Cx for 22 hr. Compared to other groups, supplementation with 40 μM 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 40 μM Cx. Oocytes treated with 40 μM 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 40 μM 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 40 μM Cx-treated group also exhibited significantly decreased expression of Bax (p < .05). Our results demonstrated that treatment with 40 μM 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.

Spermine reduces reactive oxygen species levels and decreases cryocapacitation in canine sperm cryopreservation

The objective of this study was to determine the ability of spermine to act as an antioxidant in scavenging reactive oxygen species (ROS), maintaining sperm function and decreasing cryocapacitation after cryopreservation. Although motility did not increase with spermine treatment, values for membrane integrity were significantly increased (P < 0.05). Higher percentages of linearity and straightness with a lower amplitude of lateral head displacement (ALH) indicated that spermine inhibits hyperactivation. Concentrations of intracellular and extracellular ROS were decreased in the treatment group (P < 0.05). Higher expression of an anti-apoptotic gene (Bcl-2) and lower expression of a pro-apoptotic gene (Bax), together with decreased expression of the mitochondrial ROS modulator ROMO1, DNA repair due to oxidative damage (OGG1), spermine synthase (SMS), NADPH oxidase associated with motility (NOX5) and spermine amino oxidase (SMOX), all showed that 5.0 mM spermine treatment was beneficial to spermatozoa. Furthermore, the proportion of live spermatozoa with intact acrosomes after thawing in the treatment group was higher than in the control. After incubation in canine capacitating medium, numbers of live capacitated spermatozoa with reacted acrosomes were higher than in the control. Our results indicate that 5.0 mM spermine is an optimal concentration for maintaining sperm function, reducing ROS production, preventing apoptosis and adverse effects of cryocapacitation during canine sperm cryopreservation.