Coculture with follicular shell pieces can enhance the developmental competence of pig oocytes after in vitro fertilization: relevance to intracellular glutathione

Antioxidant Effects of Myo-Inositol Improve the Function and Fertility of Cryopreserved Boar Semen

During cryopreservation, sperm undergoes structural and molecular changes such as ice crystal formation, DNA fragmentation, and reactive oxygen species (ROS) production, leading to decreased sperm quality after thawing. Antioxidants play a crucial role in preventing these damages, both in vivo and in vitro. One potent antioxidant is myo-inositol, known for its protective effects on sperm against ROS. This study aimed to investigate the protective effect of myo-inositol on cryopreserved boar semen. The semen was diluted, cooled, and cryopreserved using a BF5 extender. It was then divided into five groups: control and different concentrations of myo-inositol (0.5, 1, 1.5, and 2 mg/mL). The post-thaw evaluation included assessments of motility, viability, acrosome integrity, mitochondrial membrane potential (MMP), caspase activity, gene expression, ROS levels, apoptosis, and IVF with treated semen. Results showed that myo-inositol at 0.5 mg/mL improved motility, acrosome integrity, and fertilization ability. It also reduced the expression of pro-apoptotic genes and increased SMCP expression. Lower concentrations also demonstrated improved viability and reduced apoptosis and ROS levels. In conclusion, myo-inositol treatment during cryopreservation improved sperm quality, reduced apoptosis and ROS levels, and enhanced fertility rates in boar semen.

Establishment and optimization of an in vitro guinea pig oocyte maturation system

Guinea pigs are a valuable animal model for studying various diseases, including reproductive diseases. However, techniques for generating embryos via embryo engineering in guinea pigs are limited; for instance, in vitro maturation (IVM) technique is preliminary for guinea pig oocytes. In this study, we aimed to establish and optimize an IVM method for guinea pig oocytes by investigating various factors, such as superovulation induced by different hormones, culture supplementation (e.g., amino acids, hormone, and inhibitors), culture conditions (e.g., oocyte type, culture medium type, and treatment time), and in vivo hCG stimulation. We found that oocytes collected from guinea pigs with superovulation induced by hMG have a higher IVM rate compared to those collected from natural cycling individuals. Moreover, we found that addition of L-cysteine, cystine, and ROS in the culture medium can increase the IVM rate. In addition, we demonstrated that in vivo stimulation with hCG for 3-8 h can further increase the IVM rate. As a result, the overall IVM rate of guinea pig oocytes under our optimized conditions can reach ~69%, and the mature oocytes have high GSH levels and normal morphology. In summary, we established an effective IVM method for guinea pig oocytes by optimizing various factors and conditions, which provides a basis for embryo engineering using guinea pigs as a model.

The role of highly dispersed silica nanoparticles in the realization of the effects of granulosa on the maturation and fertilization competence of <i>Sus scrofa domesticus</i> oocytes

Reproductive technologies are some of the key directions in the context of the need to preserve and select highly productive farmed animals in terms of economically useful traits. Improvements of the existing models of the in vitro oocyte maturation system help to solve the problem of low yield of porcine embryos at the final stages of preimplantation development. In the present study, a model of culture medium for gametes (NCSU-23 with 10 % homologous follicular fluid, 10 IU hCG and 10 IU eCG) modernized by the addition of 1·106 granulosa cells (GCs) per ml and 0.001 % of highly dispersed silica nanoparticles (HDSn) is proposed for use in the IVM and IVF technology of donor porcine oocytes. Analysis of the oocyte chromatin status by the Tarkowsky method and assessment of the level of destructive changes in chromatin (apoptosis, pyknosis) revealed a significant percentage increase in matured oocytes and a decrease in the proportion of granulosa cells with degenerated chromatin when using the original culture system. The positive effects of a joint addition of GCs and HDSn to the maturation system have made it possible to increase the indicators of the meiotic maturation and fertilization of oocytes. Optimal results of developmental competence of oocytes were achieved with the joint use of GCs and HDSn in the maturation system (the proportion of matured cells reached 89 %, the level of oocytes with chromosome degeneration was 12 %, 39 % of embryos reached the final stage of preimplantation development). The positive effect of HDSn on oocyte fertilization was accompanied by an abrupt decrease in destructive processes in GCs during culture in the presence of HDSn. The level of somatic cells with pyknotic nuclei was 32 % and the level of apoptosis (TUNELtest), 21 %, compared with the control (43 and 31 %, p <0.01, respectively). Thus, a high efficiency of the porcine oocyte maturation system in the joint culture of gametes with GCs and HDSn was revealed. It makes it possible to recommend a model of this culture medium at the IVM of female gametes of Sus scrofa domesticus for improving the quality of donor oocytes used in cell and genetic engineering.

Cryopreservation and oxidative stress in porcine oocytes

Several vitrification protocols have been established for porcine oocytes so as to facilitate gene banking of female germplasm. Although live piglets have been successfully produced from pig oocytes vitrified at the germinal vesicle (GV) stage, the competence of vitrified oocytes to develop into the blastocyst stage is greatly compromised following cryopreservation. The focus of this review is to elucidate the impact of cryopreservation on the redox balance of pig oocytes, making special reference to the relevance of non-enzymatic and enzymatic antioxidant defences. Besides, the regulation of gene expression in response to oxidative stress is also considered. Finally, we discuss the effects of supplementing maturation and vitrification media with the exogenous non-enzymatic antioxidants that have hitherto yielded the most relevant results.

Metabolic co-dependence of the oocyte and cumulus cells: essential role in determining oocyte developmental competence

BACKGROUND

Within the antral follicle, the oocyte is reliant on metabolic support from its surrounding somatic cells. Metabolism plays a critical role in oocyte developmental competence (oocyte quality). In the last decade, there has been significant progress in understanding the metabolism of the cumulus-oocyte complex (COC) during its final stages of growth and maturation in the follicle. Certain metabolic conditions (e.g. obesity) or ART (e.g. IVM) perturb COC metabolism, providing insights into metabolic regulation of oocyte quality.

OBJECTIVE AND RATIONALE

This review provides an update on the progress made in our understanding of COC metabolism, and the metabolic conditions that influence both meiotic and developmental competence of the oocyte.

SEARCH METHODS

The PubMed database was used to search for peer-reviewed original and review articles. Searches were performed adopting the main terms 'oocyte metabolism', 'cumulus cell metabolism', 'oocyte maturation', 'oocyte mitochondria', 'oocyte metabolism', 'oocyte developmental competence' and 'oocyte IVM'.

OUTCOMES

Metabolism is a major determinant of oocyte quality. Glucose is an essential requirement for both meiotic and cytoplasmic maturation of the COC. Glucose is the driver of cumulus cell metabolism and is essential for energy production, extracellular matrix formation and supply of pyruvate to the oocyte for ATP production. Mitochondria are the primary source of ATP production within the oocyte. Recent advances in real-time live cell imaging reveal dynamic fluctuations in ATP demand throughout oocyte maturation. Cumulus cells have been shown to play a central role in maintaining adequate oocyte ATP levels by providing metabolic support through gap junctional communication. New insights have highlighted the importance of oocyte lipid metabolism for oocyte oxidative phosphorylation for ATP production, meiotic progression and developmental competence. Within the last decade, several new strategies for improving the developmental competence of oocytes undergoing IVM have emerged, including modulation of cyclic nucleotides, the addition of precursors for the antioxidant glutathione or endogenous maturation mediators such as epidermal growth factor-like peptides and growth differentiation factor 9/bone morphogenetic protein 15. These IVM additives positively alter COC metabolic endpoints commonly associated with oocyte competence. There remain significant challenges in the study of COC metabolism. Owing to the paucity in non-invasive or in situ techniques to assess metabolism, most work to date has used in vitro or ex vivo models. Additionally, the difficulty of measuring oocyte and cumulus cell metabolism separately while still in a complex has led to the frequent use of denuded oocytes, the results from which should be interpreted with caution since the oocyte and cumulus cell compartments are metabolically interdependent, and oocytes do not naturally exist in a naked state until after fertilization. There are emerging tools, including live fluorescence imaging and photonics probes, which may provide ways to measure the dynamic nature of metabolism in a single oocyte, potentially while in situ.

WIDER IMPLICATIONS

There is an association between oocyte metabolism and oocyte developmental competence. Advancing our understanding of basic cellular and biochemical mechanisms regulating oocyte metabolism may identify new avenues to augment oocyte quality and assess developmental potential in assisted reproduction.

Effect of crocetin added to IVM medium for prepubertal goat oocytes on blastocyst outcomes after IVF, intracytoplasmic sperm injection and parthenogenetic activation

Crocetin is an active constituent of saffron recently used as antioxidant for embryo culture. The aim of this study was to test the effect of crocetin added in the in vitro maturation (IVM) of prepubertal goat oocytes on the embryo development after in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI) and parthenogenetic activation (PA). Cumulus-oocyte complexes (COCs) were released from slaughterhouse ovaries of prepubertal goats and in vitro matured in supplemented TCM 199 medium during 24 h without (control group) and with crocetin. In Experiment 1, we evaluated the effect of the IVM supplementation with 0 μM (control), 0.5 μM, 1 μM and 2 μM of crocetin on the blastocyst development after IVF. No significant differences were obtained on blastocyst formation among groups (12, 7, 10, 11%; respectively). Although the blastocyst total cell number was higher in 1 μM crocetin group (150.7 cells) compared to the control (105.5), 0.5 μM (116.2) and 2 μM (93.7) crocetin groups, no significant differences were detected. In experiment 2, we assessed the effect of 1 μM crocetin supplementation in the IVM medium on the oocyte GSH level, ROS level and mitochondrial activity. ROS was significantly higher in the control than in the crocetin group (P < 0.05), but no differences in GSH level and mitochondrial activity were observed. In experiment 3, we evaluated the effect of 1 μM crocetin on the blastocyst development of oocytes after ICSI and PA. No statistical differences were found on blastocyst rate or cell number. However, compared with control, crocetin groups led to higher cleavage (59 vs. 67%, respectively, P = 0.09) and blastocyst rates (19 vs. 12%, respectively; P = 0.12) after ICSI. Although crocetin reduced ROS levels in prepubertal goat oocytes, it did not have a significant effect on oocyte embryo developmental competence.

Improve the developmental competence of porcine oocytes from small antral follicles by pre-maturation culture method

The oocytes from small antral follicle have low developmental potential to reach blastocyst due to incomplete cytoplasmic maturation during in vitro maturation (IVM). Thus, we developed an in vitro culture system for porcine oocytes derived from small antral follicles with l-ascorbic acid supplement during pre-maturation (pre-IVM) to support their development to blastocyst stage. Besides that, how l-ascorbic acid effect on the developmental competence of porcine oocytes with a special focus on histone modifications will be elucidated. The in vitro culture process consisted of two steps. The first step is 22 h of pre-IVM and the second step is 42 h of IVM. We utilized dibutyryl-cyclicAMP (dbcAMP) with L-ascorbic supplement during pre-IVM. Based on the result of this procedure, we proposed that the best culture condition in which hormone human chorionic gonadotropin (hCG) be added during the last 7 h of pre-IVM and continued culture to complete IVM. We observed that, in this culture system, the meiotic competence of porcine oocytes derived from small follicles was as high as those derived from large follicles after undergoing IVM. In addition, our study suggested that l-ascorbic acid supplementation at 100 μg/mL sharply enhanced the developmental potential of porcine oocytes. Interestingly, oocytes from small antral follicles treated with l-ascorbic acid could obtain the blastocyst quantity and quality as high as that of large antral follicles. The treated groups showed a significantly higher number of blastomeres compared to those in non-treated groups in both small and large follicle groups. Besides that, = The increasing levels of acetylation of histone H3 at lysine 9 (H3K9) and methylation of histone H3 at lysine 4 (H3K4) in blastocyst derived from small and large antral follicle under the present of l-ascrobic acid lead to a significant positive effect on the developmental competence and improvement in quality of porcine embryos.

Melatonin protects in vitro matured porcine oocytes from toxicity of Aflatoxin B1

Aflatoxin B1 (AFB1) is a major food and feed contaminant that threaten public health. Previous studies indicate that AFB1 exposure disrupted oocyte maturation. However, an effective and feasible method is unavailable for protecting oocytes against toxicity of AFB1. In the present study, using in vitro matured porcine oocytes and parthenogenetic embryos as model, we confirmed that AFB1 exposure during in vitro oocyte maturation (IVM) significantly impaired both nuclear and cytoplasmic maturation in a dose- and time-dependent manner. The different concentrations of melatonin were also tested for their protective effects on oocytes against the AFB1-induced toxicity. Our results showed that supplementation of a relative high concentration of melatonin (10^-3 mol/L) during IVM efficiently reversed the impaired development rate and blastocyst quality, to the levels comparable to those of the control group. Further analysis indicated that melatonin application efficiently alleviated reactive oxygen species accumulation and initiation of apoptosis induced by AFB1 exposure. In addition, disrupted GSH/GPX system, as well as inhibited mitochondrial DNA (mtDNA) replication and mitochondrial biogenesis in AFB1-treated oocytes, can be notably reversed by melatonin application. Furthermore, cumulus cells may be important in mediating the toxicity of AFB1 to oocytes, and the metabolism of AFB1 in cumulus cells can be depressed by melatonin. To the best of our knowledge, this is the first report to confirm that melatonin application can efficiently protect oocytes from AFB1-induced toxicity. Our study provides a promising and practical strategy for alleviating or reversing AFB1-induced female reproductive toxicity in both clinical treatment and domestic reproductive management.

Supplementation of culture medium with L-carnitine improves the development and cryotolerance of in vitro-produced porcine embryos

Porcine oocytes and embryos contain substantial amounts of lipid, with little known regarding its metabolic role during development. This study investigated the role of lipid metabolism and the interaction between carbohydrate and lipid substrates in porcine embryos. Following in vitro fertilisation, presumptive zygotes were transferred to culture medium supplemented with L-carnitine, a co-factor required for the metabolism of fatty acids. In porcine zygote medium-3 (PZM-3), which contains pyruvate and lactate, 3mM L-carnitine was the only dose that improved cleavage rates compared with the control. In the absence of carbohydrates, all doses of L-carnitine from 1.5 to 12mM increased cleavage rates compared with the control. Culture in a PZM-3-based sequential media system (Days 0-3: pyruvate and lactate; Days 4-7: glucose) significantly increased blastocyst cell numbers compared with culture in standard PZM-3. Supplementing PZM-3 with 3mM L-carnitine produced blastocysts with cell numbers equivalent to those obtained in the sequential media system. After vitrification, the post-warming survival rates of blastocysts obtained in media supplemented with 3mM L-carnitine were significantly greater than those of blastocysts obtained in standard PZM-3. In conclusion, L-carnitine supplementation improved embryo development when the medium contained pyruvate and lactate or was lacking carbohydrates completely, indicating a role for fatty-acid metabolism when the embryo's requirements for carbohydrates are not adequately met.

NMR spectroscopy of single sub-nL ova with inductive ultra-compact single-chip probes

Nuclear magnetic resonance (NMR) spectroscopy enables non-invasive chemical studies of intact living matter. However, the use of NMR at the volume scale typical of microorganisms is hindered by sensitivity limitations, and experiments on single intact organisms have so far been limited to entities having volumes larger than 5 nL. Here we show NMR spectroscopy experiments conducted on single intact ova of 0.1 and 0.5 nL (i.e. 10 to 50 times smaller than previously achieved), thereby reaching the relevant volume scale where life development begins for a broad variety of organisms, humans included. Performing experiments with inductive ultra-compact (1 mm²) single-chip NMR probes, consisting of a low noise transceiver and a multilayer 150 μm planar microcoil, we demonstrate that the achieved limit of detection (about 5 pmol of ¹H nuclei) is sufficient to detect endogenous compounds. Our findings suggest that single-chip probes are promising candidates to enable NMR-based study and selection of microscopic entities at biologically relevant volume scales.

Effect of Antioxidants (β-mercaptoethanol and Cysteamine) on Assisted Reproductive Technology In vitro

INTRODUCTION

Oocyte Culture of Germinal Vesicle (GV) and its growth improves Assisted Reproductive Technology (ART) invitro and infertility. Inappropriate culture medium environment, low quality of oocytes, increase in Oxidative Stress (OS) events, Reactive Oxygen Species (ROS) and free radicals production are the main factors that result in unsuccessful Invitro Maturation (IVM) and decrease in reproduction.

AIM

The present study was conducted with the aim to evaluate the effect of β-mercaptoethanol (BME) and Cysteamine (CYS) on IVM improvement, embryo fertilization and development of blastocyst of mouse immature oocyte.

MATERIALS AND METHODS

Oocytes were obtained from 4-6 weeks old Naval Medical Research Institute (NMRI) female mice, 48 hours after stimulation with Intraperitoneal (IP) injection of 10 IU Pregnant Mare Serum Gonadotropin (PMSG). GV oocyte with and without cumulus cells were isolated from ovaries and cultured in Tissue Culture Medium (TCM) 199 with availability of 100 μM of antioxidants (BME and CYS). After 24 hours, mature oocyte in metaphase II (MII) were fertilized with sperm in In vitro Fertilization (IVF) medium (T6) and evaluated for fetal development into blastocyst.

RESULTS

BME and CYS could significantly (p<0.05) increase the rate of IVM and oocyte evolution, and embryo formation in medium culture. Furthermore, it is demonstrated that existence of Cumulus Oocyte Complexes (COC) significantly showed better IVM, fertilization and evolution trend as compared to oocytes without cumulus cover or Denuded Oocytes (DO), especially in TCM199 plus BME and CYS. So that the change in GV stage oocytes to MII (maturation rate), fertilization rates or 2PN formation, and two cell embryos formation or blastocyst development rate in the treatment group with addition of BME & CYS and COC was statistically significant as compared to the DO group (p-value < 0.0001).

CONCLUSION

Both cellular and environmental factors could be important and involved in ART improvement.

Antioxidant supplementation overcomes the deleterious effects of maternal restraint stress-induced oxidative stress on mouse oocytes

In this study, using a mouse model, we tested the hypothesis that restraint stress would impair the developmental potential of oocytes by causing oxidative stress and that antioxidant supplementation could overcome the adverse effect of stress-induced oxidative stress. Female mice were subjected to restraint stress for 24 h starting 24 h after equine chorionic gonadotropin injection. At the end of stress exposure, mice were either killed to recover oocytes forin vitromaturation (IVM) or injected with human chorionic gonadotropin and caged with male mice to observein vivodevelopment. The effect of antioxidants was testedin vitroby adding them to IVM medium orin vivoby maternal injection immediately before restraint stress exposure. Assays carried out to determine total oxidant and antioxidant status, oxidative stress index, and reactive oxygen species (ROS) and glutathione levels indicated that restraint stress increased oxidative stress in mouse serum, ovaries, and oocytes. Whereas the percentage of blastocysts and number of cells per blastocyst decreased significantly in oocytes from restraint-stressed mice, addition of antioxidants to IVM medium significantly improved their blastocyst development. Supplementation of cystine and cysteamine to IVM medium reduced ROS levels and aneuploidy while increasing glutathione synthesis and improving pre- and postimplantation development of oocytes from restraint-stressed mice. Furthermore, injection of the antioxidant epigallocatechin gallate into restraint-stressed mice significantly improved the blastocyst formation and postimplantation development of their oocytes. In conclusion, restraint stress at the oocyte prematuration stage impaired the developmental potential of oocytes by increasing oxidative stress and addition of antioxidants to IVM medium or maternal antioxidant injection overcame the detrimental effect of stress-induced oxidative stress. The data reported herein are helpful when making attempts to increase the chances of a successful outcome in human IVF, because restraint was applied at a stage similar to the FSH stimulation period in a human IVF program.

Developmental potential of prepubertal mouse oocytes is compromised due mainly to their impaired synthesis of glutathione

Although oocytes from prepubertal animals are found less competent than oocytes from adults, the underlying mechanisms are poorly understood. Using the mouse oocyte model, this paper has tested the hypothesis that the developmental potential of prepubertal oocytes is compromised due mainly to their impaired potential for glutathione synthesis. Oocytes from prepubertal and adult mice, primed with or without eCG, were matured in vitro and assessed for glutathione synthesis potential, oxidative stress, Ca²⁺ reserves, fertilization and in vitro development potential. In unprimed mice, abilities for glutathione synthesis, activation, male pronuclear formation, blastocyst formation, cortical granule migration and polyspermic block were all compromised significantly in prepubertal compared to adult oocytes. Cysteamine and cystine supplementation to maturation medium significantly promoted oocyte glutathione synthesis and blastocyst development but difference due to maternal age remained. Whereas reactive oxygen species (ROS) levels increased, Ca²⁺ storage decreased significantly in prepubertal oocytes. Levels of both catalytic and modifier subunits of the γ-glutamylcysteine ligase were significantly lower in prepubertal than in adult oocytes. Maternal eCG priming improved all the parameters and eliminated the age difference. Together, the results have confirmed our hypothesis by showing that prepubertal oocytes have a decreased ability to synthesize glutathione leading to an impaired potential to reduce ROS and to form male pronuclei and blastocysts. The resulting oxidative stress decreases the intracellular Ca²⁺ store resulting in impaired activation at fertilization, and damages the microfilament network, which affects cortical granule redistribution leading to polyspermy.

Effect of mouse cumulus cells on the in vitro maturation and developmental potential of bovine denuded germinal vesicle oocytes

We investigated the effect mouse cumulus cells (mCCs) on the in vitro maturation (IVM) and developmental potential of bovine denuded germinal vesicle oocytes (DOs). Cumulus–oocyte complexes (COCs), DOs and DOs cocultured with either mCCs (DOs + mCCs) or bovine cumulus cells (bCCs; DOs + bCCs) were subjected to IVM. The meiosis II (MII) rates of DOs, glutathione (GSH) contents, zona pellucida (ZP) hardening and parthenogenetic blastocyst rates of MII oocytes were determined. The relative expression levels of bone morphogenetic protein 15 (BMP-15) and growth differentiation factor 9 (GDF-9) in MII oocytes were measured using quantitative real-time polymerase chain reaction (PCR). mCCs significantly increased the MII rate of DOs from 53.5 ± 3.58% to 69.67 ± 4.72% (p < 0.05) but had no effect on the GSH content (2.17 ± 0.31 pmol/oocyte with mCCs, 2.14 ± 0.53 pmol/oocyte without mCCs). For the DOs + mCCs group, the BMP-15 and GDF-9 expression levels were significantly higher and the ZP dissolution time was significantly lower (162.49 ± 12.51 s) than that of the DOs group (213.95 ± 18.87 s; p < 0.05). The blastocyst rate of the DOs + mCCs group (32.56 ± 4.94%) was similar to that of the DOs group (31.75 ± 3.65%) but was significantly lower than that of the COCs group (43.52 ± 5.37%; p < 0.05). In conclusion, mCCs increased the MII rate of DOs and expression of certain genes in MII oocytes, and decreased the ZP hardening of MII oocytes, but could not improve their GSH content or developmental potential.

Developmental potential of pig embryos reconstructed by use of sow versus pre-pubertal gilt oocytes after somatic cell nuclear transfer

In this study, the developmental ability of cloned embryos using gilt versus sow oocytes was evaluated under the hypothesis that the efficiency of nuclear transfer using gilt oocytes was lower than that of sow oocytes, but that it could be optimized. Five experiments were performed with routine production of cloned embryos with sow oocytes serving as the control. Results showed that: Experiment 1: Blastocyst rates of cloned embryos with gilt oocytes was about half compared with control. Experiment 2: An extended maturation time of 48 h used for gilt oocytes resulted in lower blastocyst rates after cloning. Experiment 3: Development of cloned embryos with gilt oocytes was improved by co-culture with sow oocytes. Experiment 4: After maturation of gilt oocytes using follicular fluid from gilt instead of sow, the oocytes were sorted into large and small oocytes, and after cloning, blastocyst rates were higher using large gilt oocytes compared with small oocytes; however, the rate remained lower compared with control. Experiment 5: Six sow recipients received a total of 503 morulae and blastocysts cloned from gilt oocytes (four recipients) and 190 cloned from sow oocytes (two recipients). All recipients became pregnant and went to term, resulting in 26 (gilt oocytes) and six (sow oocytes) piglets. In conclusion, results confirmed that nuclear transfer efficiency was higher using sow versus gilt oocytes, but the use of gilt oocytes can be optimized by sorting after ooplasm size following maturation and by maturing gilt and sow oocytes together.

Disrupted redox homeostasis and aberrant redox gene expression in porcine oocytes contribute to decreased developmental competence

The objective of this study was to identify specific redox-related genes whose function contributes to oocyte quality and to characterize the role of redox homeostasis in oocyte development. We determined the redox genes glutaredoxin 2 (GLRX2), protein disulfide isomerase family A, members 4 and 6 (PDIA4, PDIA6), and thioredoxin reductase 1 (TXNRD1) were differentially expressed between adult (more competent) and prepubertal (less competent) porcine in vitro-matured (IVM) oocytes. The association between these genes and oocyte quality was further validated by comparing transcript abundance in IVM with that in in vivo-matured (VVM) prepubertal and adult oocytes. By maturing oocytes in variable redox environments, we demonstrated that a balanced redox environment is important for oocyte quality, and over-reduction of the environment is as detrimental as excess oxidation. Critical levels of reactive oxygen species (ROS) and glutathione (GSH) are required for oocyte competence. Elevated GSH and lower ROS in prepubertal oocytes suggest disrupted redox homeostasis exists in these cells. By further comparing GLRX2, PDIA4, PDIA6, and TXNRD1 expression levels in oocytes matured under these different redox environments, we found aberrant expression patterns in prepubertal oocytes but not in adult oocytes when the maturation medium contained high concentrations of antioxidants. These results suggest that prepubertal oocytes are less competent in regulating redox balance than adult oocytes, contributing to lower oocyte quality. In conclusion, aberrant redox gene expression patterns and disrupted redox homeostasis contribute to decreased developmental competence in prepubertal and IVM porcine oocytes. The balance between ROS and GSH plays an important role in oocyte quality.

In vitro production of porcine embryos: current status, future perspectives and alternative applications

The pig is considered to be a suitable source of cells and organs for xenotransplants, as well as a transgenic animal to produce specific proteins, given the biological similarities it shares with human beings. However, the in vitro embryo production system in pigs is inefficient compared with those in other mammals, such as cattle or mice. Although numerous modifications have been applied to improve the efficiency of in vitro embryo production systems in pigs, not much progress has been made to overcome the problem of polyspermy, and low developmental ability due to insufficient cytoplasmic abilities of in vitro matured oocytes and improper culture conditions for the in vitro produced embryos. Recent achievements, such as the establishment of chemically defined medium and utilization of 'zona hardening' technique, have gained some success. However, further research for the reduction of polyspermy and detrimental effects of the culture systems in pigs is still needed.

Mouse cumulus-denuded oocytes restore developmental capacity completely when matured with optimal supplementation of cysteamine, cystine, and cumulus cells

Our objectives were to study how cysteamine, cystine, and cumulus cells (CCs), as well as oocytes interact to increase oocyte intracellular glutathione (GSH) and thereby to establish an efficient in vitro maturation system for cumulus-denuded oocytes (DOs). Using M16 that contained no thiol as maturation medium, we showed that when supplemented alone, neither cystine nor cysteamine promoted GSH synthesis of mouse DOs, but they did when used together. Although goat CCs required either cysteamine or cystine to promote GSH synthesis, mouse CCs required both. In the presence of cystine, goat CCs produced cysteine but mouse CCs did not. Cysteamine reduced cystine to cysteine in cell-free M16. When TCM-199 that contained 83 microM cystine was used as maturation medium, supplementation with cysteamine alone had no effect, but supplementation with 100 microM cysteamine and 200 microM cystine increased blastulation of DOs matured with CC coculture to a level as high as achieved in cumulus-surrounded oocytes (COCs). Similar numbers of young were produced after two-cell embryos from mouse COCs or CC-cocultured DOs matured with optimal thiol supplementation were transferred to pseudopregnant recipients. It is concluded that 1) mouse CCs can use neither cysteamine nor cystine to promote GSH synthesis, but goat CCs can use either one; 2) goat CCs promote mouse oocyte GSH synthesis by reducing cystine to cysteine, but how they use cysteamine requires further investigation; and 3) mouse DOs can use neither cystine nor cysteamine for GSH synthesis, but they restore developmental capacity completely when matured in the presence of optimum supplementation of cysteamine, cystine, and CCs.

Gene expression and development of early pig embryos produced by serial nuclear transfer

During nuclear transfer, reprogramming makes the donor nucleus capable of directing development of the reconstructed embryo. In most cases reprogramming is incomplete, which leads to abnormal expression of early embryonic genes and subsequently, to reduced developmental potential. In the present study, we monitored the expression of Oct4, Nanog, and Sox2 in cloned porcine embryos and evaluated whether serial nuclear transfer, the transfer of nuclei of cloned embryos into enucleated oocytes, has the potential to provide a more complete reprogramming of the donor genome. The data suggested that Nanog and Sox2 expression is properly reactivated after nuclear transfer, but the relative abundance of Oct4 transcripts is abnormally low in cloned porcine blastocysts compared to control embryos produced by in vitro fertilization. When the nuclei of 8- to 16-cell stage cloned embryos were introduced into enucleated oocytes to expose the chromosomes repeatedly to the ooplasmic factors, the resulting embryos showed poor developmental potential: a significantly lower percentage of embryos developed to the 4-cell (12.0% vs. 31.8%), 8-cell (3.1% vs. 15.0%) and blastocyst (0% vs. 8.7%) stages compared to those produced following a single round of nuclear transfer (P < 0.05). The additional time for reprogramming also did not improve gene expression. By the late 4-cell stage, Oct4 and Sox2 expression levels were low in serial nuclear transfer embryos compared to those in embryos generated by in vitro fertilization or nuclear transfer. Overall, both developmental and gene expression data indicated that reprogramming of the donor nucleus could not be improved by serial nuclear transfer in the pig.

Abnormal changes in mitochondria, lipid droplets, ATP and glutathione content, and Ca(2+) release after electro-activation contribute to poor developmental competence of porcine oocyte during in vitro ageing

The present study aims to investigate major changes in porcine oocytes during ageing in vitro. After the oocytes were cultured for 44, 56, 68 and 80 h, changes to porcine oocytes in ultrastructure, mitochondrial distribution, glutathione (GSH) and ATP content, Ca(2+) release patterns and developmental competence after electro-activation were observed. Mitochondria were evenly distributed in oocytes at 44 h, aggregated in clusters or in peripheral cytoplasm at 68 h and dimly dispersed throughout ooplasm at 80 h. Mitochondrial shape during ageing was also observed by transmission electron microscopy (TEM) at the same time intervals. Most mitochondria were spherical at 44 h, and became elongated when the culture time was extended to 68 h and 80 h. Moreover, mitochondrial clustering became increasingly loose from 56 h. Lipid droplets in oocytes appeared prominent and electron-dense at 44 h, but electron density was lost at 56 h. Lipid droplets were solidified as of 68 h. There was an age-dependent decrease in ATP content per oocyte. Glutathione content per oocyte decreased significantly and remained lower after 56 h. Amplitudes of [Ca(2+)] rise decreased dramatically following 56 h, and the time required for [Ca(2+)] to plateau became shorter after electro-activation with prolonged culture time. Cleavage and blastocyst rates of aged oocytes progressively decreased, while the fragmentation rate gradually increased after electro-activation. It is concluded that abnormal changes in mitochondria, lipid droplets, Ca(2+) release after electro-activation, and ATP and GSH content in oocytes during ageing may result in poor developmental competence of parthenotes.

Osmolarity at early culture stage affects development and expression of apoptosis related genes (Bax-alpha and Bcl-xl) in pre-implantation porcine NT embryos

This study examined whether high osmolarity of culture medium at the early culture stage affects development and expression of apoptosis related genes (Bax-alpha and Bcl-xl) of porcine nuclear transfer (NT) and in vitro fertilization (IVF) embryos. NT and IVF embryos were divided into three groups and the basic medium was PZM-3 (260-270 mOsmol, control group). The control group of embryos was cultured in PZM-3 for whole culture period. Other two groups of embryos were cultured in a modified PZM-3 with 0.05 M sucrose (300-320 mOsmol, sucrose group) or increased NaCl to 138 mM (300-320 mOsmol, NaCl group) for the first 2 days, and then cultured in PZM-3 for 4 days. NT embryos cultured in NaCl group showed a significantly higher developmental rate to the blastocyst stage with a decreased apoptosis rate compared to the control (P < 0.05). There was no difference in blastocyst formation and apoptosis incidence among the three culture treatments for IVF-derived embryos. Bax-alpha mRNA expression was significantly higher in the control than sucrose or NaCl group for both NT and IVF embryos (P < 0.05). Moreover, the relative abundance of Bax-alpha/Bcl-xl was higher in the control than the treatment groups. These results indicate that the higher osmolarity at the early embryonic stage of porcine NT and IVF embryos can improve the in vitro development with reduced apoptosis through regulating the Bax-alpha/Bcl-xl gene expression.

The interactions between cysteamine, cystine and cumulus cells increase the intracellular glutathione level and developmental capacity of goat cumulus-denuded oocytes

To improvein vitromaturation (IVM) of denuded oocytes (DOs), we observed the interactive effects of cysteamine, cystine and cumulus cells on the glutathione (l-γ-glutamyl-l-cysteinyl-glycine; GSH) level and developmental capacity of goat IVM oocytes. Cysteamine supplementation increased the GSH level and blastocyst rates of both cumulus–oocyte complexes (COCs) and DOs, while the addition of cystine increased the GSH level and blastulation only in the presence of cumulus cells (COCs or DOs co-cultured on a cumulus cell monolayer). Simultaneous supplementation of cysteamine and cystine increased the GSH content and blastulation of co-cultured DOs to a level similar to that of COCs matured without thiol supplementation. Co-culture without thiol supplementation improved DOs' GSH synthesis but not blastulation. The results suggest that DOs cannot utilize cystine for GSH synthesis unless exogenous cysteamine is supplied by either cumulus cells or supplementation. Thus, while the addition of cystine alone is enough to improve IVM of COCs, improvement of DOs requires supplementation of both cystine and cysteamine. Synergic actions between cysteamine, cystine and cumulus cells restore the GSH level and developmental capacity of goat DOs.

Mechanisms of oxidative stress in porcine oocytes and the role of anti-oxidants

The mechanisms of oxidative stress in in vitro maturing porcine oocytes and the effects of anti-oxidant supplementation of the medium in ameliorating these effects were investigated in the present study. In addition to intracellular reduced glutathione (GSH) concentrations and DNA fragmentation, the present study focused on superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase activity. The anti-oxidants used were N-acetylcysteine (NAC) and its derivative NAC-amide (NACA). The results indicate that when SOD is inhibited, supplementation of the maturarion medium with 1.5 mm NAC or NACA compensates for the decrease in SOD activity by reducing the degree of DNA fragmentation (P < 0.05). When GPx is inhibited, supplementation of the maturarion medium with 1.5 mm NAC alleviates the effects of no GPx activity, as indicated by a decrease in the degree of DNA fragmentation (P < 0.05). When the maturarion medium was supplemented with 1.5 mm NACA, intracellular GSH concentrations decreased (P < 0.05) and SOD and catalase activities increased (P < 0.05) along with the degree of DNA fragmentation. These results indicate that the mechanisms of alleviating oxidative stress in porcine oocytes are very complex and supplementing maturing oocytes with anti-oxidants may enhance enzyme activities and eliminate free radicals.

Polyspermic penetration in porcine IVM-IVF systems

Although techniques for in vitro production of porcine embryos have proceeded very rapidly during the past decade, polyspermic penetration still remains a persistent obstacle to porcine in vitro fertilization (IVF) systems. Considerable research on in vitro polyspermic penetration in porcine in vitro-matured (IVM) oocytes has been undertaken to try to solve this problem. In the current paper, recent advancements in overcoming the problems of polyspermy in porcine IVF systems are reviewed. Partial induction of the acrosome reaction of boar spermatozoa in IVF media that contain caffeine is likely to be one of the major causes of polyspermy. A reduction in the number of incompletely acrosome-reacted spermatozoa, which can bind tightly to the zona pellucida and mask free sperm receptors of the zona pellucida, could reduce the incidence of polyspermic penetration; however, morphological differences in the reaction of the zona pellucida have been observed between IVM and ovulated oocytes, which suggests that altered zona morphology may be another cause of polyspermic penetration. It has been shown that the developmental ability of polyspermic porcine embryos to the blastocyst stage is similar to that of normal embryos but that developmental competence to term is much lower. To overcome the current problems of polyspermy, it is suggested that future efforts should be focused on controlling boar sperm function and/or sperm-zona binding to achieve the final maturation associated with normal zona modifications of porcine oocytes at fertilization.

Role of follicle stimulating hormone and epidermal growth factor in the development of porcine preantral follicle in vitro

The aim of the present study was to assess the role of follicle stimulating hormone (FSH), epidermal growth factor (EGF) or a combination of EGF and FSH on the in vitro growth of porcine preantral follicles, estradiol secretion, antrum formation, oocyte maturation and subsequent embryonic development. Porcine preantral follicles were cultured for 3 days in the absence or in the presence of FSH or EGF. Oocytes from these follicles were then matured, fertilized in vitro and embryos were cultured. Estradiol secretion and histological analysis of cultured follicles were also carried out. The results showed that when FSH, or a combination of EGF and FSH, was added to the culture medium, most of preantral follicles grew to antral follicles with high estradiol secretion and the oocytes from these antral follicles could mature, fertilize and develop to the blastocyst stage. Without FSH, or a combination of EGF and FSH, preantral follicles were unable to develop to the antral stage. Histology demonstrated that the resulting follicles were nonantral, estradiol production was reduced and none of their oocytes matured after in vitro maturation. The results indicate the essential role of FSH in promoting in vitro growth of porcine preantral follicle, estradiol secretion, antrum formation, oocyte maturation and subsequent embryonic development. EGF with FSH treatment of porcine preantral follicles improves the quality of oocytes, shown by a higher frequency of embryonic development.

Modification of maturation condition improves oocyte maturation and in vitro development of somatic cell nuclear transfer pig embryos

This study examined effects on the developmental competence of pig oocytes after somatic cell nuclear transfer (SCNT) or parthenogenetic activation (PA) of : 1) co-culturing of oocytes with follicular shell pieces (FSP) during in vitro maturation (IVM); 2) different durations of maturation; and 3) defined maturation medium supplemented with polyvinyl alcohol (PVA; control), pig follicular fluid (pFF), cysteamine (CYS), or beta-mercaptoethanol (beta-ME). The proportion of metaphase II oocytes was increased (p < 0.05) by co-culturing with FSP compared to control oocytes (98% vs. 94%). However, blastocyst formation after SCNT was not improved by FSP coculture (9% vs. 12%). Nuclear maturation of oocytes matured for 39 or 42 h was higher (p < 0.05) than that of oocytes matured for 36 h (95-96% vs. 79%). Cleavage (83%) and blastocyst formation (26%) were significantly higher (p < 0.05) in oocytes matured for 42 h than in other groups. Supplementation of a defined maturation medium with 100 microM CYS or 100 microM beta-ME showed no stimulatory effect on oocyte maturation, embryo cleavage, or blastocyst formation after PA. beta-ME treatment during IVM decreased embryo cleavage after SCNT compared to pFF or PVA treatments, but no significant difference was found in blastocyst formation (7-16%) among the four treatment groups. The results indicated that maturation of oocytes for 42 h was beneficial for the development of SCNT embryos. Furthermore, the defined maturation system used in this study could support in vitro development of PA or SCNT embryos.

Effects of ovarian cortex cell co-culture during in vitro maturation on porcine oocytes maturation, fertilization and embryo development

The objective of the experiments was to evaluate the effects of porcine ovarian cortex cells (pOCCs) during in vitro maturation (IVM) of porcine oocytes on IVM of porcine oocytes, in vitro fertilization (IVF) parameters and subsequent embryo development. The pOCCs was cultured in the 500 microl TCM199 without hormone until the confluence, and then cultured in 500 microl TCM199 supplemented with hormone for 12 h before the oocytes added. Porcine oocytes were co-cultured with the pOCCs monolayers in the co-culture system for 44 h, following fertilized in the mTBM for 6 h. Finally, the presumptive zygotes were cultured for 144 h in the NCSU-23 supplemented with 0.4% BSA. The results showed that matured M II oocytes in the co-culture group were higher than that in the control group (P<0.05). Although penetration did not differ between the co-culture and control groups (P=0.481), polyspermy declined in the co-culture group (P<0.05), whereas male pronucleus (MPN) formation was improved in the co-culture group compared with the control group (P<0.05). More blastocysts developed in the co-culture group than that in the control group (P<0.05); however, the cleavage rates and the mean number cells per blastocyst showed no significant difference between the treated group and the control group (P=0.560 and 0.873, respectively). In conclusion, the presence of the pOCCs monolayers during IVM enhanced the maturation quality of the porcine oocytes, reduced the polyspermy, increased the percentages of MPN formation and blastocyst, but the blastocyst quality was not improved.

Mammalian embryo co-culture: Trials and tribulations of a misunderstood method

Embryo-somatic cell co-culture was devised over 40 years ago in an attempt to improve the development and viability of mammalian preimplantation embryos generated and cultured in vitro. While initial endeavours were successful in this respect, other studies soon highlighted a number of significant long-term detrimental impacts of this approach. Surprisingly little is known about the mechanisms underlying the beneficial effects of co-culture, although the production of embryotrophic compounds, modulation of nutrient profile, protection against culture-induced stress and/or toxin clearance are all contenders. The extent to which the inadvertent exposure of embryos to serum accounts for many of these effects remains open to question. Although the popularity of somatic cell co-culture has recently declined in favour of the use of sequential media due to concerns associated with its risk of disease transmission and long-term sequelae, we argue that complete dismissal of this technique is ill advised, given that our limited understanding of basic somatic cell interactions has prevented us from fully exploiting its potential. In this respect, there is some merit in focussing future research strategies based on reconstructed maternal tract tissue. Although the use of co-culture in clinical practice is unacceptable and its implementation in domestic species for commercial purposes should be viewed with diffidence, this technique can still provide a wealth of information on the development of novel, more physiological embryo in vitro culture systems. The proviso for acquiring such information is to gain a fuller understanding of the culture requirements/biochemistry of somatic cells and their interaction with the early conceptus.

Antihyaluronidase Action of Ellagic Acid Effectively Prevents Polyspermy As a Result of Suppression of the Acrosome Reaction Induced by Sperm-Zona Interaction During In Vitro Fertilization of Porcine Oocytes

The present study was conducted to examine the effects of three tannin relatives (tannic acid, TA; gallic acid, GA; and ellagic acid, EA) on antihyaluronidase and reactive oxygen species (ROS) scavenging activity, in vitro fertilization (IVF) parameters, and the acrosome reaction (AR) induced by sperm-zona interaction. Among the three tannin relatives, TA and EA showed the strongest potency for blocking the hyaluronidase activity of boar sperm, with concentration-dependent inhibition over the range of 2-10 microg/ml. In contrast, ROSs were effectively scavenged by TA and GA, but not EA. When cumulus-free oocytes were inseminated in IVF medium containing 5 microg/ml of the tannin relatives, polyspermy was significantly reduced by TA and EA (32 and 29%, respectively) compared with oocytes treated with or without GA (51 and 69%, respectively) under conditions that maintained a high sperm penetration rate (P<0.05). Interestingly, induction of the AR by treatment of preincubated sperm with progesterone was blocked by TA and GA as a result of their higher levels of ROS scavenging activity, while EA, which possessed weak ROS scavenging activity, did not disturb induction of the AR with progesterone. However, the incidence of AR induced by sperm-zona interaction was significantly decreased by the strong antihyaluronidase actions of TA and EA compared with that in the absence of these compounds. Treatment with the compounds caused neither a protective proteolytic modification of the zona pellucida matrix before fertilization nor a reduction in acrosomal proteolytic activity or the number of zona-bound sperm. These findings suggest that the antihyaluronidase action of EA effectively prevents polyspermy by suppression of AR functionality induced by sperm-zona interaction and that hyaluronidase intervention is therefore required during porcine IVF.

Serial nuclear transfer improves the developmental potential of mouse embryos cloned from oocytes matured in a protein-free medium

Germinal vesicle (GV) oocytes matured in vitro are an alternative source for cytoplasmic recipients of nuclear transfer (NT). However, the developmental potential of oocytes matured in vitro is limited. In this study, we developed a protein-free maturation medium for mouse GV oocytes. Following parthenogenetic activation, the oocytes matured in the protein-free medium develop to blastocyst stage with a high efficiency, even up to the rate obtained from in vivo MII-oocytes (90.6% vs. 92.8%). Using the oocytes matured in the protein-free medium as the recipient, NT embryos develop to the blastocyst stage (17.6%). To further improve the developmental potential of NT embryos, we performed serial NT and compared the effect of three different activated cytoplasm samples derived from in vitro matured oocytes as the second recipient, that is, the effect of in vitro fertilized (IVF) zygote, the preactivated cytoplast and the IVF cytoplast, on the development of NT embryos. We found that when the pronucleus of NT zygote was transferred into the cytoplasm of the IVF zygote, the blastocyst formation increased to 39.4%. This is the first report to demonstrate the IVF zygote from oocytes matured in protein-free medium can be used successfully as the recipient for serial NT to enhance the developmental potential of mouse NT embryos from oocytes matured in the protein-free medium.

Maintenance of Meiotic Arrest and Developmental Potential of Porcine Oocytes after Parthenogenetic Activation and Somatic Cell Nuclear Transfer

Several studies report that meiotic maturation of porcine oocytes can be reversibly preserved. The present study examined how long meiotic maturation can be suppressed. The first experiment determined the preservation medium suitable for reversibly suppressing meiotic maturation of porcine oocytes. The second experiment examined the in vitro developmental potential of oocytes maintained in meiotic arrest after parthenogenetic activation and nuclear transfer of somatic cells. Preservation of cumulus-oocyte complexes with NCSU-37 medium containing 10% follicular fluid, 1 mM dibutyryl cyclic AMP, and follicular shell pieces for 24-96 h at 39 degrees C did not affect oocyte maturation compared with controls (94-98% vs. 98%). The potential of parthenogenetically activated and nuclear-transferred oocytes maintained in meiotic arrest for 24-48 h to develop into blastocysts was not significantly different from that of controls (20-25% vs. 18% and 8-11% vs. 9%, respectively). The present study demonstrated that meiotic maturation of porcine oocytes can be suppressed after preservation for 48 h at 39 degrees C without decreasing oocyte maturation competence or the ability of oocytes to develop to at least the blastocyst stage.

Low oxygen tension during in vitro maturation of porcine follicular oocytes improves parthenogenetic activation and subsequent development to the blastocyst stage

To establish a reliable in vitro maturation system for activation and subsequent development as nuclear recipients for the effective production of pig clones, we assessed maturation, activation and parthenogenetic development in response to the following: (1) type of immature oocytes (cumulus-oocyte complexes (COCs) or parietal granulosa plus cumulus-oocyte complexes (GCOCs)); (2) oxygen (O(2)) tension (5 or 20%); and (3) maturation period (36-60 h). The rate of nuclear maturation to metaphase-II (M-II) in the GCOC group (73.0 +/- 3.1%) was higher than that in the COC group (P < 0.05, 60.6 +/- 3.5%), but the rates did not differ between the 5 and 20% O(2) tension groups. M-II rate increased (P < 0.05) to about 70% after 42 h and then remained constant until 60 h of culture. When oocytes were matured under 5% O(2) tension and stimulated, the rate of normal oocyte activation (a female pronucleus formation and emission of the second polar body) was higher (P < 0.05, 38.5 +/- 3.9%) than when oocytes were matured under 20% O(2) tension (24.5 +/- 3.9%). On the other hand, the rate of normal activation was not significantly different between the COC and GCOC groups, and the highest (P < 0.05) normal activation rate was obtained in oocytes cultured for 48 and 54 h (48.4 +/- 5.5% and 47.9 +/- 8.2%, respectively). When COC and GCOC matured for 48 h under 5 and 20% O(2) tension were stimulated and subsequently cultured in vitro for 6 days, the rate of blastocyst formation did not differ between the oocyte types nor between the O(2) tension groups. However, blastocyst quality, as measured by mean total cell number, was significantly higher in the 5% O(2) group (P < 0.05, 34.6 +/- 2.0 for COC; 33.8 +/- 1.8 for GCOC) compared with the 20% O(2) group (25.9 +/- 1.8 for COC; 27.0 +/- 2.0 for GCOC). In conclusion, low O(2) tension (5%) during in vitro maturation of porcine oocytes promoted their ability to be activated normally and improved the quality of parthenogenetic blastocysts developed in vitro in modified NCSU-37 solutions. This knowledge may be applicable for preparation of in vitro matured oocytes with good quality as recipient oocytes for generating pig clones.

Transgenic animals as drug factories: a new source of recombinant protein therapeutics

The utility of transgenic animal bioreactors for the production of complex therapeutic proteins is based on lower production costs, higher production capacities and safer, pathogen free products. Until gene therapy becomes broadly efficacious, transgenic-derived therapeutics are the most attractive alternative for prophylactic, replacement therapy in genetic disorders, such as haemophilia. Many other disease states need short-term treatment of significant amounts of recombinant proteins that could be made amply available from transgenic animal sources. In addition, transgenic animals will provide an ideal expression system for the production of a portfolio of alternative therapeutics for patient populations developing inhibiting antibodies, for enhanced bioactivity, or for increased plasma clearance times. The FDA approval of a transgenic-derived therapeutic is still pending, but a review of Phase I & II data from antithrombin III from goat milk is encouraging, and companies are continuing to add potential therapeutics to their product pipeline.

Follicle size-dependent effects of sow follicular fluid on in vitro cumulus expansion, nuclear maturation and blastocyst formation of sow cumulus oocytes complexes

Follicular fluid from 2 to 4 and 5 to 8 mm diameter non-atretic follicles (SFF and LFF, respectively) of sows was added during IVM of cumulus oocytes complexes (COCs) to study its effects on cumulus expansion, nuclear maturation, and subsequent fertilization and embryo development in presence or absence of recombinant human FSH. COCs aspirated from 2 to 5 mm follicles of sow ovaries, were cultured for the first 22 h in TCM-199 and 100 microM cysteamine, with or without 10% pFF and/or 0.05 IU/ml recombinant hFSH. For the next 22 h, the COCs were cultured in the same medium, but without pFF and FSH. After culture, cumulus cells were removed and the oocytes were either fixed and stained to evaluate nuclear stages or co-incubated with fresh sperm. Twenty-four hours after fertilization, presumptive zygotes were fixed to examine fertilization or cultured for 6 days to allow blastocyst formation. Subsequently, embryos were evaluated and the blastocysts were fixed and stained to determine cell numbers. When LFF was added to maturation medium, cumulus expansion and percentage of nuclear maturation (277 +/- 61 microm and 72%, respectively) of COCs were significantly higher (P < 0.05) than those in SFF (238 +/- 33 microm and 55%, respectively). However, in the presence of FSH both FF stimulated cumulus expansion and nuclear maturation to a similar degree. No differences were observed with regards to sperm penetration, male pronucleus formation, and to polyspermia between fertilized oocytes matured either in SFF or LFF. Fertilized oocytes matured in the presence of LFF without or with FSH showed a higher cleavage (45 +/- 7% and 51 +/- 7%, respectively) and blastocyst (14 +/- 4% and 22 +/- 6%, respectively) formation rate compared to SFF (cleavage, 35 +/- 8% and 41 +/- 4%, blastocyst: 8 +/- 3 and 13 +/-3, respectively; P < 0.05). The mean number of cells per blastocyst did not differ significantly between treatments. These findings indicate that factor(s) within follicles at later stages of development play an important role during oocyte maturation and thereby enhance developmental competence to occur.

Effects of elevated temperature in vivo on the maturational and developmental competence of porcine germinal vesicle stage oocytes

Postslaughter processing of sow carcasses results in the ovaries being exposed to temperatures of 41.3 to 42.1 degrees C within a 30-min time frame. This study investigated whether the maturational and developmental competence of the recovered germinal vesicle stage oocytes could be compromised by post-slaughter processing. The results showed that the in vitro maturation rates of GV stage oocytes exposed to elevated temperature did not significantly differ from the corresponding controls (74.1 vs. 75.8%). Immunocytochemical staining revealed that elevated temperature did not adversely affect metaphase II spindle formation but resulted in extensive disruption of oocyte cytoskeletal organization. This, in turn, had a detrimental effect on parthenogenetic development compared with the corresponding nonheat-treated controls (cleavage rate = 27.7 vs. 65.3%, P < 0.01; blastulation rate = 6.7 vs. 20.6%, P < 0.01). Hence, transient exposure to elevated temperature during slaughter did not have any detrimental effects on nuclear maturation per se, but it did result in extensive cytoskeletal damage, which in turn drastically decreased the developmental competence.