Temporal detection of caspase-3 and -7 in bovine in vitro produced embryos of different developmental capacity

Investigating the Expression Levels of Bax and Bcl-2 Genes in Peripheral Blood Lymphocytes of Industrial Radiation Workers in the Asaluyeh Region

Background

Industrial radiography uses gamma or X-ray radionuclide sources to investigate the safety of industrial materials. Industrial radiation workers receive the highest occupational radiation doses.

Objective

The present study investigates the relationship between Bax and Bcl-2 gene expression variables in industrial radiation workers.

Material and Methods

In this case-control study, data was collected using blood sampling from 40 workers, including two groups of non-radiation and radiation workers employed at the location. Expression levels of Bax and Bcl-2 genes were assessed in the laboratory. The environmental and absorbed doses of workers were measured using environmental and pen dosimeters.

Results

Statistical analysis showed that the radiation group's Bcl-2 gene expression level was significantly higher. Findings also demonstrated a correlation between Bcl-2 gene expression and the number of workdays. Also, the Bax gene expression did not show a significant change, and the expression ratio of Bax/Bcl-2 was insignificant in the two groups.

Conclusion

Exposure to low doses of radiation could promote an adaptive response in cells by increasing Bcl-2 gene expression.

Interleukin-6 stimulates in vitro development of late-stage ovine embryos

The effect of interleukin-6 (IL-6) supplementation during the different phases of in vitro embryo culturing (IVC) on embryo development and embryonic gene expression was studied in ovine. IL-6 was added to IVC medium during the late phases (72-192 h; 5, 10, and 25 ng/ml IL-6) or entire period (0-192 h; 10 ng/ml IL-6) of IVC to determine its effect on embryo development. Further, the effect of IL-6 (10 ng/ml) supplementation at the 72 h of IVC on gene expressions associated with JAK/STAT signalling and pluripotency in 8-16 cell embryos (1 h post-supplementation) and compact morulae (48 h post-supplementation), and apoptosis and primitive endoderm (PrE) development in compact morulae was investigated. The supplementation of 10 ng/ml IL-6 during the late phases of IVC significantly (P < 0.05) increased blastocyst formation (35.2 ± 1.52%) compared to the control (21.1 ± 1.11%), and 5 ng/ml (25.9 ± 2.98%) or 25 ng/ml (16.5 ± 0.73%) IL-6 groups. Conversely, IL-6 (10 ng/ml) treatment throughout the IVC period significantly (P < 0.05) decreased the rate of cleavage (55.4 ± 1.57%) and blastocyst formation (14.5 ± 1.28%) compared to the control group (65.8 ± 1.35% and 21.5 ± 0.97%, respectively). In 8-16 cell embryos and compact morulae, the IL-6 treatment significantly (P < 0.05) affected the expression of genes associated with JAK/STAT signalling and pluripotency. Further, the treatment significantly (P < 0.05) downregulated BAX and CASP3, and upregulated GATA6 expression in compact morulae. In conclusion, IL-6 supplementation affected the in vitro development of ovine embryos in a dose- and time-dependent manner. The beneficial effect of IL-6 on the development of late-stage embryos was mediated through the changes in gene expressions associated with JAK/STAT signalling, pluripotency, apoptosis and PrE development.

Glutathione during Post-Thaw Recovery Culture Can Mitigate Deleterious Impact of Vitrification on Bovine Oocytes

Vitrification of bovine oocytes can impair subsequent embryo development mostly due to elevated oxidative stress. This study was aimed at examining whether glutathione, a known antioxidant, can improve further embryo development when added to devitrified oocytes for a short recovery period. Bovine in vitro matured oocytes were vitrified using an ultra-rapid cooling technique on electron microscopy grids. Following warming, the oocytes were incubated in the recovery medium containing glutathione (0, 1.5, or 5 mmol L^-1) for 3 h (post-warm recovery). Afterwards, the oocytes were lysed for measuring the total antioxidant capacity (TAC), activity of peroxidase, catalase and glutathione reductase, and ROS formation. The impact of vitrification on mitochondrial and lysosomal activities was also examined. Since glutathione, added at 5 mmol L^-1, significantly increased the TAC of warmed oocytes, in the next set of experiments this dose was applied for post-warm recovery of oocytes used for IVF. Glutathione in the recovery culture did not change the total blastocyst rate, while increased the proportion of faster developing blastocysts (Day 6-7), reduced the apoptotic cell ratio and reversed the harmful impact of vitrification on the actin cytoskeleton. These results suggest that even a short recovery culture with antioxidant(s) can improve the development of bovine devitrified oocytes.

RNA-Seq Reveals the Underlying Molecular Mechanism of First Cleavage Time Affecting Porcine Embryo Development

The selection and evaluation of high-quality embryos are the key factors affecting in vitro embryo development and pregnancy outcome. The timing of first embryonic cleavage has been considered a positive indicator of the in vitro developmental potential of embryos, while the underlying molecular mechanism is still not fully understood. In this study, the embryos generated by parthenogenetic activation (PA) or in vitro fertilization (IVF) were monitored and recorded every 2 h and divided into two groups (early cleavage or late cleavage) based on the cleavage rate and blastocyst formation data. RNA sequencing was used to analyze the gene expression pattern of the embryos. We identified 667 and 71 different expression genes (DEGs) in early cleavage and late cleavage porcine PA and IVF embryos, respectively. Further Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that the DEGs are mainly enriched in pathways concerning the proteasome, DNA repair, cell cycle arrest, autophagy, and apoptosis, suggesting that severe endoplasmic reticulum stress (ERS) and DNA damage may be the key factors that led to the low development potential of late cleavage embryos. This study provides a theoretical basis for the following application and offers important information about the understanding of the timely manner of porcine embryo development.

Effect of Nellore (Bos indicus) donor age on in vitro embryo production and pregnancy rate

The aim of this study was to evaluate the effect of age of Nellore (Bos indicus) donors on the efficiency of in vitro embryo production (IVEP) and pregnancy rate. Thirty-six donors, including 11 female calves (13±0.61 months), 17 prepubertal heifers (25±0.78 months) and 8 cows (83±28 months), were submitted to 3 procedures of ovum pick up (OPU) on random days of the estrous cycle at intervals of 21 days. Caspase-3 and IGFBP2 were quantified in oocytes and blastocysts for the evaluation of oocyte and embryo quality. The produced embryos were vitrified (n=445) and transferred to synchronized recipients. Cows produced a larger number of follicles (cows: 54.5±6.2; calves: 20.0±0.57; prepubertal heifers: 20.8±0.46), total oocytes (cows: 45.97±7.22; calves: 28.93±6.14; prepubertal heifers: 27.21±4.94), and cleaved oocytes (cows: 21.14±4.22; calves: 13.09±3.72; prepubertal heifers: 12.4±3.19). The cleavage rate was similar between age categories; however, cows tended (p<0.07) to produce a larger number of blastocysts (9.74±2.26) per OPU than calves (5.57±1.99) and prepubertal heifers tended to have a higher blastocyst yield (35.4%) than calves (27.1%) (p<0.07). The expression levels of IGFBP2 and caspase-3 were higher in oocytes derived from calves compared to the other two categories. The pregnancy rate was higher in calves (43.1%) and cows (40.4%) than in prepubertal heifers (33.8%) (p=0.03). Despite the larger numbers of follicles and viable oocytes in cows, the blastocyst production results and pregnancy rates obtained indicate that the use of young females as oocyte donors in IVEP is feasible and may contribute to reduce the generation interval.

Evaluation of the TMRW vapor phase cryostorage platform using reproductive specimens and in vitro extended human embryo culture

OBJECTIVE

To assess the impact of shipment and storage of sperm, oocytes, and blastocysts in vapor phase nitrogen compared with static storage in liquid phase nitrogen.

DESIGN

Prospective cohort-matched study.

SETTING

Multiple in vitro fertilization laboratories in an in vitro fertilization network.

PATIENT(S)

Fifty-eight human embryos, 32 human oocytes, 15 units of bovine semen.

INTERVENTION(S)

Vapor vs. liquid nitrogen.

MAIN OUTCOME MEASURE(S)

The postwarming survival of oocytes, sperm, and blastocysts, and the developmental potential of blastocysts during in vitro extended culture.

RESULT(S)

Custom-designed labware, for use with the TMRW platform, enables continuous temperature monitoring during shipment and/or storage in the vapor phase robotic storage system. The highest temperature recorded for specimens shipped to a domestic laboratory was -180.2 °C with a mean ± SD of -190.4 ± 0.5 °C during shipment and -181.1 ± 0.6 °C during storage. Likewise, specimens shipped internationally had a high of -180.2 °C with a mean ± SD of -193.5 ± 0.6 °C during shipment and -181.2 ± 0.7 °C during storage. Results from the extended culture assays have revealed no deleterious effect of shipment and storage in nitrogen vapor. The viability of mammalian gametes and embryos was equivalent between the vapor phase and liquid phase storage.

CONCLUSION(S)

The evaluated system did not have any deleterious effects on the postwarming survival of sperm, oocytes, and blastocysts. The postwarming developmental potential of human blastocysts during in vitro extended culture was unaffected by storage and handling in the vapor phase nitrogen TMRW platform when compared with static liquid phase nitrogen storage. Our results suggest that the vapor phase cryostorage platform is a safe system to handle and store reproductive specimens for human assisted reproductive technology.

Interaction of apoptosis and pluripotency related transcripts for developmental potential of ovine embryos produced in vitro at different oxygen concentrations

The present study in sheep model was to find out the interaction of apoptotic transcripts, that is, Bcl2, Bax, Casp3, PCNA and p53 and pluripotency related transcripts, that is, Sox2, Nanog and Oct4 in ovine embryos produced in vitro at different O₂ concentrations (20% and 5% O₂) to compare their developmental potential. Oxygen concentrations did not influence the maturation and cleavage rate but the percentage of morula and blastocysts was significantly more at 5% as compared to 20% O₂. A significant upregulated expression of Bcl2 and PCNA genes and significantly downregulated expression of Casp3 and p53 were observed in the blastocysts at 5% than those at 20% O₂. The expression of Bax was not influenced by the O₂ concentration. Among the pluripotency related transcripts, the expression of Oct4 was significantly upregulated and the expression of Sox2 and Nanog was significantly downregulated in embryos at 5% than at 20% O₂. The study concluded that the embryos produced in vitro at low O₂ (5%) concentration regulate the expression of developmental genes related to apoptosis and pluripotency to improve the developmental potential of embryos as compared to high O₂ (20%) concentration.

Use of two new formulations as bovine embryo manipulation solution

This study aimed to evaluate the effect of two Embryo Manipulation Solutions (EMS and EMS supplemented) in maintenance of the viability of embryos, initially using structures derived from mice (first phase). Next, the efficiency of these solutions in routines of bovine embryo transfer was evaluated (second stage). Mice embryos were used in the stages of early blastocyst, and compact morula grades I and II. These embryos were initially randomly distributed and maintained for four hours in three solutions: Modified phosphate buffered saline (PBS; Control); EMS (treatment 1), and EMS supplemented (treatment 2). Subsequently, they were cultured in TCM 199 medium and evaluated in terms of total number of cells, morphometric characteristics, ultra structural aspects, detection of cell apoptosis, and quantification of Hsp70.3 gene expression. In the second phase, these same solutions were tested in the transfer of quality I and II bovine embryos (excellent and good). These embryos were transferred fresh to 58 recipients. The results showed that the total number of cells in embryos expanded blastocyst (ExB), the number of apoptotic cells, the cell, nuclear, nucleolar diameter and the nucleus/nucleolus ratio was similar among the treatments. The pregnancy rate shown on second phase was also similar. However, the EMS supplemented expressed more Hsp70.3 than EMS. The expression of Hsp70.3 was also greater for embryos in EMS than that of EMS supplemented. The McII embryos, EMS and EMS supplemented samples also expressed more Hsp70.3 compared to control embryos. In conclusion, the tested solutions can be used in routine embryo transfer techniques, replacing modified PBS solution as an effective media in maintaining embryo viability.

Lipid characterization of in vitro-produced bovine embryos with distinct kinetics of development

Human embryo studies have proposed the use of additional morphological evaluations related to the moment of the first cell divisions as relevant to embryo viability. Nevertheless, there are still not enough data available related to morphokinetic analysis and its relationship with lipid composition in embryos. Therefore, the aim of this study was to address the lipid profile of bovine embryos with different developmental kinetics: fast (four or more cells) and slow (two or three cells) at 40 h post-insemination (hpi), at three time points of in vitro culture (40, 112 and 186 hpi) and compare these to profiles of in vivo embryos. The lipid profiles of embryos were analyzed by matrix-assisted laser desorption ionization mass spectrometry, which mainly detected pools of membrane lipids such as phosphatidylcholine and sphingomyelin. In addition to their structural function, these lipid classes have an important role in cell signalling, particularly regarding events such as stress and pregnancy. Different patterns of lipids in the fast and slow groups were revealed in all the analyzed stages. Also, differences between in vitro embryos were more pronounced at 112 hpi, a critical moment due to embryonic genome activation. At the blastocyst stage, in vitro-produced embryos, despite the kinetics, had a closer lipid profile when compared with in vivo blastocysts. In conclusion, the kinetics of development had a greater effect on the membrane lipid profiles throughout the embryo culture, especially at the 8-16-cell stage. The in vitro environment affects lipid composition and may compromise cell signalling and function in blastocysts.

Bovine Embryo-Secreted microRNA-30c Is a Potential Non-invasive Biomarker for Hampered Preimplantation Developmental Competence

Recently, secreted microRNAs (miRNAs) have received a lot of attention since they may act as autocrine factors. However, how secreted miRNAs influence embryonic development is still poorly understood. We identified 294 miRNAs, 114 known, and 180 novel, in the conditioned medium of individually cultured bovine embryos. Of these miRNAs, miR-30c and miR-10b were much more abundant in conditioned medium of slow cleaving embryos compared to intermediate cleaving ones. MiR-10b, miR-novel-44, and miR-novel-45 were higher expressed in the conditioned medium of degenerate embryos compared to blastocysts, while the reverse was observed for miR-novel-113 and miR-novel-139. Supplementation of miR-30c mimics into the culture medium confirmed the uptake of miR-30c mimics by embryos and resulted in increased cell apoptosis, as also shown after delivery of miR-30c mimics in Madin-Darby bovine kidney cells (MDBKs). We also demonstrated that miR-30c directly targets Cyclin-dependent kinase 12 (CDK12) through its 3′ untranslated region (3′-UTR) and inhibits its expression. Overexpression and downregulation of CDK12 revealed the opposite results of the delivery of miRNA-30c mimics and inhibitor. The significant down-regulation of several tested DNA damage response (DDR) genes, after increasing miR-30c or reducing CDK12 expression, suggests a possible role for miR-30c in regulating embryo development through DDR pathways.

Bovine uterus-derived exosomes improve developmental competence of somatic cell nuclear transfer embryos

Exosomes widely exist in various tissues and body fluids, including blood, tissue fluid, and urine. In the present study, exosomes were first isolated from the early luteal phase uterus and confirmed through morphological examination, immunofluorescence (IF) staining of special membrane antigen, and Western blot. The effects of exosomes on the developmental competence of somatic cell nuclear transfer (SCNT) embryos were investigated. Transmission electron microscopy results showed that the isolated exsomes were spherical particles with a 50 nm-150 nm diameter. Immunostaining showed that the surface of these isolated particles were CD9 positive, which was confirmed using Western blot. Supplementing SCNT embryos with these isolated exsomes on day 4 of culture significantly increased the blastocyst formation rate (31% vs. 34%, 40.3%, and 34.3%) and hatching rate (30.3% vs. 33.3%, 40.7%, and 35%) in comparison with the non-supplementation (control), and day 3 and day 5 supplementation groups. Blastocysts from the exsome supplementation groups showed higher inner cell mass/trophectoderm cell ratio (48% vs 37.9%) and lower apoptosis index (2.1% vs 6.5%) than the control group. The gene expression analysis of the blastocysts also showed that the exsomes supplementation significantly enhanced the expression levels of IFNT and acrogranin and decreased the expression levels of HSP70, BAX and BIP. In conclusion, the present study indicated that the early luteal phase uterus secretes exosomes, which might play important roles in the development of SCNT embryos.

Developmental kinetics of in vitro-produced bovine embryos: An aid for making decisions

Embryo developmental kinetics and embryo survival after cryopreservation have been correlated with embryo quality and viability. The main objectives of this work were to analyze developmental ability and quality of in vitro-produced bovine embryos in relation to their kinetics and to establish a criterion of quality to predict further viability. Embryos were classified and grouped by their specific stage of development (2, 3-4, or ≥ 5 cells) at 44 hours post insemination (hpi) and cultured separately up to Day 8. On Days 7 and 8, good quality expanded blastocysts were vitrified or frozen. Cryopreserved surviving hatched embryos were stained for cell counts. Embryos at a more advanced stage (3-4 cells, and ≥5 cells) developed to morulae (P < 0.001) and blastocysts (P < 0.01) at higher rates than those embryos that had cleaved once by 44 hpi. Vitrification improved the hatching rates of blastocysts at 48 hours (P < 0.001) when compared with slow-rate freezing within each group of embryos (3-4 cells and ≥5 cells). After vitrification/warming, blastocysts coming from 3- to 4-cell embryos had higher hatching rates at 48 hours than those that came from ≥5-cell embryos. With regard to differential cell counts, no effect of the initial developmental stage was observed after warming/thawing. However, trophectoderm and total cells were higher in vitrified/warmed than in the frozen/thawed embryos (P < 0.001). These data show that selecting IVF embryos at 44 hpi, after the evaluation of their in vitro embryo development, could be used as noninvasive markers of embryo developmental competence and may help to select IVF embryos that would be more suitable for cryopreservation.

Valproic acid enhances early development of bovine somatic cell nuclear transfer embryos by alleviating endoplasmic reticulum stress

Despite the positive roles of histone deacetylase inhibitors in somatic cell nuclear transfer (SCNT), few studies have evaluated valproic acid (VPA) and its associated developmental events. Thus, the present study was conducted to elucidate the effect of VPA on the early development of bovine SCNT embryos and the underlying mechanisms of action. The histone acetylation level of SCNT embryos was successfully restored by VPA, with optimal results obtained by treatment with 3mM VPA for 24h. Importantly, the increases in blastocyst formation rate and inner cell mass and trophectoderm cell numbers were not different between the VPA and trichostatin A treatment groups, whereas cell survival was notably improved by VPA, indicating the improvement of developmental competence of SCNT embryos by VPA. Interestingly, VPA markedly reduced the transcript levels of endoplasmic reticulum (ER) stress markers, including sXBP-1 and CHOP. In contrast, the levels of GRP78/BiP, an ER stress-alleviating transcript, were significantly increased by VPA. Furthermore, VPA greatly reduced cell apoptosis in SCNT blastocysts, which was further evidenced by the increased levels of the anti-apoptotic transcript Bcl-xL and decreased level of the pro-apoptotic transcript Bax. Collectively, these results suggest that VPA enhances the developmental competence of bovine SCNT embryos by alleviating ER stress and its associated developmental damage.

Early cleavage of handmade cloned buffalo (Bubalus bubalis) embryos is an indicator of their developmental competence and quality

Following IVF, embryos which cleave early have been shown to have higher developmental competence and quality than those that cleave relatively later across many species. We investigated the effect of time of cleavage on the developmental competence, quality, epigenetic status and gene expression in buffalo embryos produced by handmade cloning (HMC). Following classification of embryos as early cleaving (EC) or late cleaving (LC) based on whether they had cleaved or not at 24 h post in vitro culture, 54% (164/303) were found to be EC and the rest to be LC. The blastocyst rate (58.1 ± 3.4 vs 36.9 ± 1.6%, p < 0.01) and the total cell number (285.5 ± 41.9 vs 141.4 ± 36.1, p < 0.05) were higher, whereas the apoptotic index (3.6 ± 0.6 vs 12.2 ± 1.7, p < 0.01) and the global level of H3K9ac and H3K27me3 were lower (p < 0.05) in the blastocysts produced from EC than in those produced from LC embryos. The relative transcript level of CASPASE3, CASPASE7, DNMT1, DNMT3a and CDX2 was higher (p < 0.05) and that of SOX2 was lower (p < 0.05) in blastocysts produced from LC than in those produced from EC embryos, whereas the expression level of CASPASE6, P53, P21, HDAC1, OCT4 and NANOG was not significantly different between the two groups. These results show that (i) following HMC, blastocysts produced from embryos that cleave early differ from those produced from late cleaving embryos in terms of epigenetic status and expression level of many important apoptosis-, pluripotency-, trophectoderm- and epigenetics-related genes, and (ii) EC embryos are superior to LC embryos in view of their higher developmental competence and quality.

Why we should not select the faster embryo: lessons from mice and cattle

Many studies have shown that in vitro culture can negatively impact preimplantation development. This necessitates some selection criteria for identifying the best-suited embryos for transfer. That said, embryo selection after in vitro culture remains a subjective process in most mammalian species, including cows, mice and humans. General consensus in the field is that embryos that develop in a timely manner have the highest developmental competence and viability after transfer. Herein lies the key question: what is a timely manner? With emerging data in bovine and mouse supporting increased developmental competency in embryos with moderate rates of development, it is time to question whether the fastest developing embryos are the best embryos for transfer in the human clinic. This is especially relevant to epigenetic gene regulation, including genomic imprinting, where faster developing embryos exhibit loss of imprinted methylation, as well as to sex selection bias, where faster developmental rates of male embryos may lead to biased embryo transfer and, in turn, biased sex ratios. In this review, we explore evidence surrounding the question of developmental timing as it relates to bovine embryo quality, mouse embryo quality and genomic imprint maintenance, and embryo sex.

Individual commitment to a group effect: strengths and weaknesses of bovine embryo group culture

Recently, new culture devices such as Corral and Primo Vision dishes have been designed for the culture of human embryos to allow the combination of group culture plus follow-up of individual embryos. Bovine inseminated oocytes were allocated to Primo Vision dishes, Corral dishes, individual culture or classical group culture. Blastocyst development in Primo Vision dishes was similar to classical group culture (34.3 and 39.0% respectively), and better than Corral dishes or individual culture (28.9 and 28.5% respectively). In Primo Vision dishes, a higher number of ‘slow’ embryos developed to the blastocyst stage compared with their individually cultured counterparts, while no differences were observed for ‘fast’ embryos. ‘Slow’ embryos in a ‘standard drop’ had a higher chance of becoming a blastocyst compared with individual culture (OR: 2.3), whereas blastulation of ‘fast’ embryos was less efficient in a ‘delayed drop’ than in individual culture (OR: 0.3). The number of non-cleaved embryos in Primo Vision dishes did not negatively influence blastocyst development. Likewise, removing non-cleaved embryos (NC removed) and regrouping the cleaved embryos afterwards (ReGR) did not affect blastocyst development and quality compared with group culture in Primo Vision dishes (CTRL, 31.6%, NC removed, 29.3% and ReGR, 29.6%). The experiments revealed that group culture of bovine embryos in Primo Vision dishes is superior to individual culture, primarily because of the higher blastocyst rate achieved by slow embryos. Non-cleaved or arrested embryos do not hamper the ability of co-cultured bovine embryos to reach the blastocyst stage in group culture.

Equine oviduct explant culture: a basic model to decipher embryo–maternal communication

Equine embryos remain for 6 days in the oviduct and thus there is a need for an in vitro model to study embryo–oviductal interactions in the horse, since this subtle way of communication is very difficult to analyse in vivo. Until now, no equine oviduct explant culture model has been characterised both morphologically and functionally. Therefore, we established a culture system for equine oviduct explants that maintained epithelial morphology during 6 days of culture, as revealed by light microscopy and transmission electron microscopy. We demonstrated the presence of highly differentiated, tall columnar, pseudostratified epithelium with basal nuclei, numerous nucleoli, secretory granules and apical cilia, which is very similar to the in vivo situation. Both epithelium and stromal cells originating from the lamina propria are represented in the explants. Moreover, at least 98% of the cells remained membrane intact and fewer than 2% of the cells were apoptotic after 6 days of culture. Although dark-cell degeneration, which is a hypoxia-related type of cell death, was observed in the centre of the explants, quantitative real-time PCR failed to detect upregulation of the hypoxia-related marker genes HIF1A, VEGFA, uPA, GLUT1 and PAI1. Since the explants remained morphologically and functionally intact and since the system is easy to set up, it appears to be an excellent tool for proteome, transcriptome and miRNome analysis in order to unravel embryo–maternal interactions in the horse.

Rapidly cleaving bovine two-cell embryos have better developmental potential and a distinctive mRNA pattern

Mammalian embryos that rapidly reach the two-cell stage in culture have a higher probability of becoming viable blastocysts. Our goal was to separate two-cell bovine embryos based on their zygotic cleavage timing, and to assess their global mRNA levels. Following in vitro fertilization, all embryos that cleaved by 29.5 hpi (early) were cultured separately from those that divided at 46 hpi (late). The blastocyst rates were 46.1 ± 3.7% and 6.1 ± 3.4% for early- and late-cleavers, respectively (P < 0.01). Seven replicates of selected two-cell embryos were collected at each time point for microarray characterization (n = 4) and quantitative reverse-transcriptase PCR (n = 3); the rest were left in culture for blastocyst evaluation. A total of 774 and 594 probes were preferentially present in early- and late-cleaving embryos, respectively (fold change ± 1.5, P < 0.05), with important contrasts related to cell cycle, gene expression, RNA processing, and protein degradation functions. A total of 12 transcripts were assessed by quantitative PCR, of which ATM, ATR, CTNNB1, MSH6, MRE11A, PCNA, APC, CENPE, and GRB2 were in agreement with the hybridization results. Since most of these molecules are directly or indirectly associated with cell-cycle regulation, DNA damage response, and transcription control, our results strongly suggest key roles for those biological functions in mammalian preimplantation development.

The utility of Brilliant Cresyl Blue (BCB) staining of mammalian oocytes used for in vitro embryo production (IVP)

The present article summarizes the results of experiments investigating the Brilliant Cresyl Blue (BCB) staining for selection of immature oocytes before in vitro embryo production or somatic cell nuclear transfer. Developmental competence of oocytes stained with BCB and quality of blastocysts derived from such oocytes as well as the expression of apoptosis-related genes, mitochondrial DNA (mtDNA) replication-related genes and the transcripts encoded by the mitochondrial genome in BCB stained oocytes are discussed.

Oocyte quality determines bovine embryo development after fertilisation with hydrogen peroxide-stressed spermatozoa

Exposure of gametes to specific stressors at sublethal levels can enhance the gametes’ subsequent performance in processes such as cryopreservation. In the present study, bull spermatozoa were subjected to H2O2 for 4 h at 100-, 200- and 500-μM levels; computer-assisted sperm analysis (CASA) and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) assay were used for evaluation of subsequent sperm motility and DNA integrity, respectively. Exposure of spermatozoa to H2O2 did not affect sperm motility but DNA integrity was negatively affected by 500 μM H2O2 compared with mock-exposed spermatozoa, whereas both motility and DNA integrity were affected compared with untreated spermatozoa. Nevertheless, insemination of oocytes with spermatozoa exposed to 200 μM H2O2 increased fertilisation, cleavage and blastocyst rates (P < 0.05). Furthermore, the higher blastocyst yield after fertilisation of oocytes with spermatozoa exposed to 200 μM H2O2 was related to oocyte diameter, with large–medium oocytes yielding higher blastocyst rates, while small-diameter oocytes consistently failed to develop into blastocysts. In conclusion, the results indicate that exposure of spermatozoa to 200 μM H2O2 before sperm–oocyte interaction may enhance in vitro embryo production in cattle. However, this increased embryo production is largely dependent on the intrinsic quality of the oocytes.

Presence of cleaved caspase 3 in swine embryos of different developmental capacities produced by parthenogenetic activation

This study assessed the presence of cleaved caspase 3 (CC3) during the in vitro development of swine embryos produced by parthenogenetic activation (PA). Embryos with high and low capacity to develop into blastocysts and the exposure to a caspase inhibitor (z-DEVD-fmk) were used to investigate the effect of CC3 on embryo development. The blastocyst rate (64.3% vs. 16.4%) and the average number of nuclei per blastocyst (39.7 vs. 19.8) were significantly higher (P < 0.05) in early- (before 24 hr) compared to late- (between 24 and 48 hr) cleaving embryos after PA. CC3 was mainly detected in the cytoplasm of Day-2 and -4 embryos, but was primarily localized in the nucleus of Day-5 and -6 embryos. The fluorescence signal for CC3 relative to negative controls was significantly higher (P < 0.05) in early- (2.42-fold) compared to late-cleaving (1.39-fold) embryos at Day 2 of culture. Treatment with z-DEVD-fmk during the first 24 or 48 hr of the culture period resulted in more embryos developing into blastocysts compared to the control group (55.8% and 55.1% vs. 37%, respectively; P < 0.05). This study confirmed the presence of CC3 in PA embryos from the two-cell to the blastocyst stage, and revealed that CC3 cellular-localization changed during embryo development. CC3 was shown to be more abundant in early-cleaving and more developmentally competent embryos compared to late-cleaving and less developmentally competent embryos. The inhibition of caspase activity at the beginning, but not at the end, of the culture period affected development of PA embryos.

The endothelial nitric oxide synthase/nitric oxide system is involved in the defective quality of bovine oocytes from low mid-antral follicle count ovaries

In a previous survey concerning cows of reproductive age, we demonstrated that oocytes isolated from ovaries with <10 medium antral follicles of 2 to 6 mm in diameter (low ovaries; Lo) show less developmental competence than oocytes collected from ovaries with >10 medium antral follicles (high ovaries; Hi). The aim of the present study was to evaluate whether a defective endothelial nitric oxide synthase/nitric oxide (eNOS/NO) system and vasculature in healthy medium antral follicles is likely to reduce oocyte competence from Lo ovaries. Thus, experiments were conducted to 1) immunolocalize eNOS protein during folliculogenesis; 2) quantify eNOS protein/vasculature in the follicle wall; and 3) verify if NO donor, S-nitroso acetyl penicillamine (SNAP) administration during in vitro maturation affects developmental competence of oocytes isolated from Lo ovaries. Endothelial nitric oxide synthase protein was detected in granulosa and theca cells, as well as in blood vessels from primordial to antral follicles. Quantitative analysis indicated that in medium antral follicles from Lo ovaries, eNOS protein expression and vasculature were reduced (P < 0.05). The addition of SNAP improved blastocyst and hatching rates of oocytes from Lo ovaries, promoting a percentage similar to oocytes from Hi ovaries, and reduced the percentage of apoptotic nuclei in in vitro-produced blastocysts (P < 0.05). Results from our study suggest that in bovine ovaries with small mid antral follicle number, a defective eNOS/NO system is related to a reduced follicle vasculature and may affect oocyte quality, thus inducing a premature decline of fertility.

Lineage-specific expression of heterochromatin protein 1gamma in post-compaction, in vitro-produced bovine embryos

Heterochromatin protein 1gamma (HP1gamma) is a highly conserved regulator of euchromatic and heterochromatic gene expression. Mammalian HP1gamma is essential for both successful preimplantation embryo development and maintenance of pluripotency in embryonic stem cells in vitro. Here, we describe HP1gamma protein localisation in matured (MII) bovine oocytes and IVF preimplantation embryos at defined developmental stages. HP1gamma is expressed in post-compaction embryos in a highly lineage-specific pattern. In embryonic stages preceding the maternal to embryonic transition (MET), HP1gamma protein was primarily cytoplasmic, whereas in 8-16-cell embryos (post MET), HP1gamma was primarily nuclear. Lineage-specific patterns of HP1gamma protein localisation become evident from compaction, being restricted to peripheral, extraembryonic cells at the morula and blastocyst stages (Days 7-9). Surprisingly, we detected HP1gamma mRNA in both embryonic and extraembryonic cells in blastocysts by fluorescence in situ hybridisation. In trophectoderm cells, HP1gamma protein was localised in specific patterns at the mitotic and interphase stages of the cell cycle. These results demonstrate lineage- and cell cycle-specific patterns of HP1gamma protein localisation in the post-compaction, preimplantation bovine embryo and raise interesting questions about the role of HP1gamma in early embryo development.

Study on pretreatment of FPS-1 in rats with hepatic ischemia-reperfusion injury

This study was designed to determine whether FPS-1, the water-soluble polysaccharide isolated from fuzi, protected against hepatic damage in hepatic ischemia-reperfusion injury in rats, and its mechanism. SD rats were subjected to 60 min of hepatic ischemia, followed by 120 min reperfusion. FPS-1 (160 mg/kg/day) was administered orally for 5 days before ischemia-reperfusion injury in treatment group. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and albumin (ALB) were assayed to evaluate liver functions. Liver samples were taken for histological examination and determination of malondialdehyde (MDA), superoxide dismutase (SOD), that catalase (CAT) in liver. Na(+)-K(+)-ATPase and Ca(2+)-ATPase in mitochondria were measured with colorimetry method. Morphological changes were also investigated by using both light microscopy and electron microscopy (EM). In addition, apoptosis and oncosis were detected by Annexin V-FITC/PI immunofluorescent flow cytometry analysis. Serum AST and ALT levels were elevated in groups exposed to ischemia-reperfusion (p < 0.05). Ischemia-reperfusion caused a marked increase in MDA level, and significant decreases in hepatic SOD and CAT (p < 0.05). Na(+)-K(+)-ATPase and Ca(2+)-ATPase were reduced in ischemia-reperfusion groups compared to the sham group (p < 0.05). Oncosis and apoptosis were also observed in ischemia-reperfusion groups. Pretreatment with FPS-1 reversed all these biochemical parameters as well as histological alterations, evidently by increased SOD, CAT, reduced MDA and histological scores compared to the model group (p < 0.05). FPS-1 could attenuate the necrotic states by the detection of immunofluorescent flow cytometry analysis. Pretreatment with FPS-1 reduced hepatic ischemia-reperfusion injury through its potent antioxidative effects and attenuation of necrotic states.

Short-term exposure to hydrogen peroxide during oocyte maturation improves bovine embryo development

Recent studies have shown that short-term exposure of oocytes to a stressor such as hydrostatic pressure or osmotic stress might induce stress tolerance in embryos. The aim of the present study was to investigate the consequences of short-term hydrogen peroxide (H(2)O(2)) exposure to bovine in vitro matured cumulus-oocyte complexes (COCs) on subsequent preimplantation embryo development and apoptosis. In the first experiment, mature COCs were incubated in H(2)O(2) at concentrations ranging between 0.01 and 100 micromol/l, and subsequently fertilized and cultured. Oocyte incubation with 50-100 micromol/l of H(2)O(2) resulted in a significantly higher blastocyst yield (47.3%) in comparison with control medium (31.8%), while apoptotic cell ratio was inversely related with H(2)O(2) concentration. In the second experiment, we showed that the stress tolerance after H(2)O(2) exposure was not mediated by increased glutathione content in treated oocytes nor by enhanced fertilization or penetration. Further research should concentrate on the potential role of players that have been associated with stress tolerance in somatic cell lines.

Expression and putative function of fibronectin and its receptor (integrin alpha(5)beta(1)) in male and female gametes during bovine fertilization in vitro

Fibronectin (Fn) is a 440 kDa glycoprotein assumed to participate in sperm-egg interaction in human. Recently, it has been demonstrated that Fn--when present during bovine IVF--strongly inhibits sperm penetration. The present study was conducted firstly to evaluate the expression of Fn and its integrin receptor (alpha(5)beta(1)) on male and female bovine gametes using indirect immunofluorescence and secondly, to determine the function of Fn during bovine IVF. Endogenous Fn was detected underneath the zona pellucida (ZP) and integrin alpha(5) on the oolemma of cumulus-denuded oocytes. Bovine spermatozoa displayed integrin alpha(5) at their equatorial segment after acrosome reaction. We established that the main inhibitory effect of exogenously supplemented Fn was located at the sperm-oolemma binding, with a (concurrent) effect on fusion, and this can probably be attributed to the binding of Fn to spermatozoa at the equatorial segment, as shown by means of Alexa Fluor 488-conjugated Fn. Combining these results, the inhibitory effect of exogenously supplemented Fn seemed to be exerted on the male gamete by binding to the exposed integrin alpha(5)beta(1) receptor after acrosome reaction. The presence of endogenous Fn underneath the ZP together with integrin alpha(5) expression on oolemma and acrosome-reacted (AR) sperm cell surface suggests a 'velcro' interaction between the endogenous Fn ligand and corresponding receptors on both (AR) sperm cell and oolemma, initiating sperm-egg binding.

Influence of nitric oxide during maturation on bovine oocyte meiosis and embryo development in vitro

The effect of s-nitroso-n-acetyl-l,l-penicillamine (SNAP, a nitric oxide donor) during in vitro maturation (IVM) on nuclear maturation and embryo development was investigated. The effect of increasing nitric oxide (NO) during prematuration or maturation, or both, on embryo development was also assessed. 10–3 m SNAP nearly blocked oocytes reaching metaphase II (MII) (7%, P < 0.05) while 10–5 m SNAP showed intermediate proportions (55%). For 10–7 m SNAP and controls (without SNAP), MII percentages were similar (72% for both, P > 0.05), but superior to the other treatment groups (P < 0.05). Blastocyst development, however, was not affected (38% for all treatments, P < 0.05). TUNEL-positive cells in hatched blastocysts (Day 9) increased when IVM included 10–5 m SNAP (8 v. 3 to 4 cells in the other treatments, P > 0.05), without affecting total cell numbers (240 to 291 cells, P > 0.05). When oocytes were prematured followed by IVM with or without 10–7 m SNAP, during either culture period or both, blastocyst development was similar (26 to 40%, P > 0.05). When SNAP was included during both prematuration and IVM, the proportion of Day 9 hatched embryos increased (28% v. 14 to 19% in the other treatments, P < 0.05). Apoptotic cells, however, increased when SNAP was included (6 to 10 cells) in comparison to prematuration and maturation without SNAP (3 cells, P < 0.05). NO may be involved in meiotic progression and apoptosis during embryo development.

Gamete origin in relation to early embryo development

Fertilization in vivo requires a complex series of selection events to occur in order to guarantee that only the fittest gametes take part in the fusion process and give rise to a viable embryo. Conventional practice in bovine in vitro fertilization however is to select oocytes and sperm by quite crude procedures. It is therefore not inconceivable that essentially unfit gametes may drive aberrant embryo development in vitro. Abnormal embryonic cells are being removed by apoptosis, which is a physiological process in embryos. Only an excess or a lack of apoptosis can lead to embryonic death or abnormal development. Suboptimal culture conditions undoubtedly contribute to undue embryonic apoptosis, but the intrinsic quality of the oocyte may also be a causative factor. It is generally accepted that the oocyte is in control of early embryogenesis, but is it also in control of future embryonic suicide? Is a compromised follicular environment predestining the oocyte to a dire fate? What is the contribution of the cumulus cells to oocyte quality, and can they rescue it from early demise? And what can be said about the origin of the spermatozoa? Research in human in vitro fertilization has definitely shown that factors such as paternal age, smoking and other sperm stressors can contribute to abnormal embryo development and even diseased offspring. This review will address the questions raised above, and will describe what is known about the cellular and molecular biology that may account for abnormal bovine embryo development caused by gamete origin.