Early Cleavage Embryos Research Articles

Late embryo cleavage as an indicator of chromosome aneuploidy by pre-implantation genetic screening

During in vitro fertilization (IVF), not all patients receive good quality oocytes or embryos. This study investigated the frequency of aneuploidy and mosaicism in embryos obtained from parthenogenetic oocytes and poor morphological embryos that also exhibited late cleavage development by preimplantation genetic screening (PGS). Twenty late cleavage embryos under IVF treatment were cultured until day 5, and one of the blastomeres was biopsied. The embryos were divided into three groups (parthenogenetic oocytes and poor-quality embryos with dark cytoplasm, several vacuoles or fragments in the cytoplasm; arrested embryos; and good-quality embryos). All samples were tested for abnormalities using array-comparative genomic hybridization (a-CGH). Twenty late cleavage-stage embryos were biopsied and analyzed for aneuploidy. A total 17 of 20 (85%) embryos were aneuploid and three (15%) were euploid. The incidence of aneuploidy in good-quality embryos was 75%, while poor-quality embryos displayed a higher frequency (86.7%) of aneuploidy. The parthenogenetic oocytes were invariably aneuploid (100%). Based on the embryo-grading system by Veeck, embryo grades 1 and 2 exhibited a lower incidence of aneuploidy (75%), while grades 3 and 4 showed 1.33-times higher aneuploidy rates (RR = 1.33; p < 0.001). The numerical defects of the chromosomes increased with the percent of fragmentation, with fragmented embryos showing 1.32-times greater aneuploidy rates than the non-fragmented ones. Embryos with uneven blastomeres showed 1.07-times higher aneuploidy rate when compared with embryos showing even blastomeres (p < 0.0064). Late embryo cleavage results in a higher incidence of aneuploidy and mosaicism upon comparison with early embryo cleavage.

Melatonin protects against defects induced by deoxynivalenol during mouse oocyte maturation.

Deoxynivalenol (DON) is one of the most prevalent fusarium mycotoxins in feedstuff and food. DON causes detrimental effects on human and animal reproductive systems by inducing oxidative stress and apoptosis. However, melatonin is a multifunctional endogenous hormone that plays crucial roles in the development of animal germ cells and embryos as a robust deoxidizer. In this study, we explored the effects of melatonin on the DON exposure mouse oocytes. Our in vitro and in vivo results showed that DON adversely affected mouse oocyte maturation and early embryo cleavage, while melatonin administration ameliorated the toxic effects of DON. DON exposure disrupted the meiotic spindle formation and kinetochore-microtubule attachment, which induced aneuploidy in oocytes. This might be through DON effects on the acetylated tubulin level. Moreover, we found that DON exposure caused the alteration of DNA and histone methylation level, which might affect early embryo cleavage. The toxic effects of DON on oocytes might be through its induction of oxidative stress-mediated early apoptosis, while the treatment with melatonin significantly ameliorated these phenotypes in DON-exposed mouse oocytes. Collectively, our results indicated the protection effects of melatonin against defects induced by DON during mouse oocyte meiotic maturation.

Functional role of AKT signaling in bovine early embryonic development: potential link to embryotrophic actions of follistatin

BackgroundTGF-β signaling pathways regulate several crucial processes in female reproduction. AKT is a non-SMAD signaling pathway regulated by TGF-β ligands essential for oocyte maturation and early embryonic development in the mouse, but its regulatory role in bovine early embryonic development is not well established. Previously, we demonstrated a stimulatory role for follistatin (a binding protein for specific members of TGF-β superfamily) in early bovine embryonic development. The objectives of the present studies were to determine the functional role of AKT signaling in bovine early embryonic development and embryotrophic actions of follistatin.MethodsWe used AKT inhibitors III and IV as pharmacological inhibitors of AKT signaling pathway during the first 72 h of in vitro embryo culture. Effects of AKT inhibition on early embryonic development and AKT phosphorylation were investigated in the presence or absence of exogenous follistatin.ResultsPharmacological inhibition of AKT signaling resulted in a significant reduction in early embryo cleavage, and development to the 8- to 16-cell and blastocyst stages (d7). Treatment with exogenous follistatin increased AKT phosphorylation and rescued the inhibitory effect of AKT inhibitors III and IV on AKT phosphorylation and early embryonic development.ConclusionsCollectively, results suggest a potential requirement of AKT for bovine early embryonic development, and suggest a potential role for follistatin in regulation of AKT signaling in early bovine embryos.

Expression and distribution of the zinc finger protein, SNAI3, in mouse ovaries and pre-implantation embryos.

The Snail gene family includes Snai1, Snai2, and Snai3 that encode zinc finger-containing transcriptional repressors in mammals. The expression and localization of SNAI1 and SNAI2 have been studied extensively during folliculogenesis, ovulation, luteinization, and embryogenesis in mice. However, the role of SNAI3 is unknown. In this study, we investigated the expression of SNAI3 during these processes. Our immunohistochemistry data showed that SNAI3 first appeared in oocytes by postnatal day (PD) 9. Following this, SNAI3 was found to be expressed consistently in theca and interstitial cells, along with oocytes. In gonadotropin-treated immature mice, the expression of SNAI3 did not change significantly during follicular development. The expression of SNAI3 was reduced during ovulation, after which it increased gradually during luteinization. Similar results were obtained from western blot analyses. Furthermore, real-time polymerase chain reaction (RT-PCR) analyses revealed varying mRNA levels of different Snail factors at a given time in gonadotropin-induced ovaries. During early embryo cleavage, SNAI3 was localized to the nucleus, except the nucleolus at the germinal vesicle and one-cell stages. From two- to eight-cell stages, SNAI3 was localized only to the nucleolus. Thereafter, SNAI3 was detected only in the cytoplasm, except during the blastocyst stage when it was localized to the nucleus of the trophectoderm and the inner cell mass. RT-PCR results showed that the expression of Snail superfamily genes was decreased during the blastocyst stage. From the eight-cell to morula stage, when compaction occurs that is a prerequisite for blastocyst formation, Snai3 mRNA was expressed at very low levels and was opposite to the highest expression level of the compaction-related gene, E-cadherin, at the eight-cell stage. Taken together, our results suggest that SNAI3 likely plays some roles during folliculogenesis, luteinization, and early embryonic development.

Reliability and agreement on embryo assessment: 5 years of an external quality control programme.

An external quality-control programme for morphology-based embryo quality assessment, incorporating a standardized embryo grading scheme, was evaluated over a period of 5 years to determine levels of inter-observer reliability and agreement between practising clinical embryologists at IVF centres and the opinions of a panel of experts. Following Guidelines for Reporting Reliability and Agreement Studies, the Gwet index and proportion of positive (Ppos) and negative agreement were calculated. For embryo morphology assessment, a substantial degree of reliability was measured between the centres and the panel of experts (Gwet index: 0.76; 95% CI 0.70 to 0.84). The agreement was higher for good- versus poor-quality embryos. When multinucleation or vacuoles were observed, low levels of reliability were obtained (Ppos: 0.56 and 0.43, respectively). In blastocysts, the characteristic that presented the largest discrepancy was that related to the inner cell mass. In decisions about the final disposition of the embryo, reliability between centre and the panel of experts was moderate (Gwet index: 0.51; 95% CI 0.41 to 0.60). In conclusion, the ability of clinical embryologists to evaluate the presence of multinucleation and vacuoles in the early cleavage embryo, and to determine the category of the inner cell mass in blastocysts, needs to be improved.

Effects of High Dose Lysophosphatidic Acid Supplement during IVC on Preimplantation Development of Porcine Embryos

Lysophosphatidic acid (LPA) is an important signaling molecule. Here, the effect and mechanism of LPA on the preimplantation development of porcine embryos during in vitro culture (IVC) was examined. Porcine embryos were cultured in porcine zygote medium (PZM-3) supplemented with 30 μM LPA during different days. There was a significantly higher cleavage rate in Day 1-7 and significantly higher total cell number of blastocysts in Day 1-3 and Day 4-7. It was also found that messenger RNA (mRNA) expression level of PCNA, BCL2 and BAX in blastocysts obtained from D1-7 group were significantly higher and BCL2/BAX mRNA ratio in D1-3 group was significantly lower than control group but Day 4-7 and Day 1-7 groups were comparable with control group. Treatment with 20 μM PLC inhibitor significantly decreased the embryo cleavage rate and blastocyst formation rate. Moreover, LPA as an activator of PLCs, enhanced the 30 μM LPA + 20 μM U73122 group embryo cleavage rate which similar with control group. In conclusion, the results suggest that treatment with LPA during IVC improves the porcine early embryo cleavage by activation of PLC signaling pathway and regulate the mRNA expression that contribute to total cell number of blastocysts during blastocyst formation.

Relief of endoplasmic reticulum stress enhances DNA damage repair and improves development of pre-implantation embryos.

Early-cleaving embryos are known to have better capacity to reach the blastocyst stage and produce better quality embryos compared to late-cleaving embryos. To investigate the significance of endoplasmic reticulum (ER) stress on early embryo cleavage kinetics and development, porcine embryos produced in vitro were separated into early- and late-cleaving groups and then cultured in the absence or presence of the ER stress inhibitor tauroursodeoxycholic acid (TUDCA). Developing embryos were collected at days 3 to 7 of culture for assessment of ER stress status, incidence of DNA double-strand breaks (DSBs), development and total cell number. In the absence of TUDCA treatment, late-cleaving embryos exhibited ER stress, higher incidence of DNA DSBs, as well as reductions in development to the blastocyst stage and total embryo cell numbers. Treatment of late-cleaving embryos with TUDCA mitigated these effects and markedly improved embryo quality and development. These results demonstrate the importance of stress coping responses in early developing embryos, and that reduction of ER stress is a potential means to improve embryo quality and developmental competence.

The effect of follicullar fluid pesticides and polychlorinated biphenyls concentrations on intracytoplasmic sperm injection (ICSI) embryological and clinical outcome

ObjectivesThe present study evaluated the correlation between the concentrations of polychlorinated biphenyls (PCBs) and pesticides in the follicular fluid (FF) obtained during intracytoplasmic sperm injection (ICSI) with the ovarian response, endometrial thickness, and embryological and clinical outcomes. DesignCross-sectional observational study. Materials and methodsWomen aged 20 to 38 years (300 infertile couples) presenting to a university-affiliated fertility center were approached to participate in the study. Only 150 couples that underwent ICSI for male factor infertility agreed to participate, and 94 of them had retrieved enough FF samples suitable for laboratory testing. The FF sample was obtained, centrifuged, and stored in liquid nitrogen. Two organochlorine pesticides (OCPs), Lindane and DDT;three organophosphates (OPs);chlorpyrifos;Diazinon; malathion; one Chloroacetanilide (Pretilachlor);two pyrethroids(Bioallethrin and β-cyfluthrin); and the concentrations of four PCBs, 28, 52, 138, 180, were estimated in the obtained FF samples by using gas chromatography/mass spectrometry. SPSS statistical analysis program (version 17) was used for analysis. Multiple regression analysis was used to correlate the PCBs and pesticides with ICSI outcomes. ResultsThere were significant negative correlations between FF concentrations of the eight examined pesticides and the four PCBs on the endometrial thickness. However, Pretilachlor, chlorpyrifos, β-cyfluthrin, and Diazinon were the only toxic agents that negatively correlated with the number of the oocytes retrieved. Fertilization and early embryo cleavage rates were negatively correlated with Pretilachlor and β-cyfluthrin. Moreover, high concentrations of Lindane,DDT, Diazinon,and chlorpyrifos were significantly associated lower implantation rate. PCB 28 and 180 concentration in the FF was associated with a lower number of retrieved oocytes and fertilization rate, respectively. The number of implanted embryos was negatively correlated with PCB 52 FF concentration. However, the clinical pregnancy rate did not reach the level of significance. ConclusionHigher concentrations of any studied PCBs and pesticides are associated with thinner endometrial thickness. The higher the level of Pretilachlor, β-cyfluthrin, PCB 28 and 180, the lower the retrieval, fertilization, and embryo cleavage rates. High PCB and pesticide concentrations in the FF adversely affected embryological ICSI outcomes. However, more data are needed to evaluate their effect on the clinical outcome.

The role of L-type calcium channels in mouse oocyte maturation, activation and early embryonic development

Calcium ion fluctuation is closely related to the transformation of cell cycle. However, little is known about the function of L-type calcium channel in mammalian oocyte and embryo development. We thus studied the roles of L-type calcium channel in mouse oocyte meiotic maturation, parthenogenetic activation and early embryonic development. We used the antagonist Amlodipine to block L-type calcium channel. Oocytes or zygotes were cultured to different time points with 0 μM, 10 μM, 30 μM and 50 μM Amlodipine. Then we checked the rate of first polar body extrusion, spindle formation, asymmetric division parthenogenetic activation and early embryo cleavage. The results showed that Amlodipine treatment did not affect germinal vesicle breakdown, but caused disruption of cytoskeleton organization, symmetric division, formation of mature oocytes with a large polar body, or reduced the first polar body extrusion, depending on its concentrations. Amlodipine treatment also resulted in decreased parthenogenetic activation and arrested early embryonic development. Overall, these data suggest that proper function of L-type calcium channel is critical for oocyte maturation, activation, and early embryonic development.

Transcutaneous Electrical Acupoint Stimulation Improves the Outcomes of In Vitro Fertilization: A Prospective, Randomized and Controlled Study

To explore whether transcutaneous electrical acupoint stimulation (TEAS) can improve the outcomes of in vitro fertilization (IVF). A prospective, randomized, and controlled study. IVF center in a university hospital. Four hundred and eighty-one infertile patients with bilateral tubal blockage who were referred for IVF. Patients were randomized into four groups. TEAS was administered for 30min, respectively, at 24h before TVOR and two hours before ET. The acupoints included SP10 (Xuehai, bilateral), SP8 (Diji, bilateral), LR3 (Taichong, bilateral), ST36 (Zusanli, bilateral), EX-CA1 (Zigong, bilateral), RN4 (Guanyuan), PC6 (Neiguan, bilateral), and RN12 (Zhongwan). Based on different frequencies of TEAS, patients were grouped into a TEAS-2Hz group, a TEAS-100Hz group and a TEAS-2/100Hz group. Patients in the control group only received routine IVF treatment and no TEAS was applied on them. The number of mature oocytes, normally fertilized oocytes and good-quality embryos were used to evaluate oocyte developmental competence of the patients. Data of clinical pregnancy rate (CPR), implantation rate (IR), and live birth rate (LBR) were also obtained. The levels of neuropeptide Y (NPY), transforming growth factor alpha and granulocyte colony-stimulating factor in the follicular fluids were measured with enzyme-linked immunosorbent assay (ELISA). No significant differences were found between the control, TEAS-2Hz, TEAS-100Hz and TEAS-2/100Hz groups on the numbers of metaphase II oocytes, normally fertilized zygotes, early cleavage embryos or good quality embryos (P > .05). However, the CPR, IR and LBR of the TEAS-2/100Hz group were significantly higher than those of the other groups, respectively (P < .05). The NPY levels in the follicular fluids of TEAS-2/100Hz group were significantly higher than those of the other groups (P < .05). TEAS using a frequency of 2/100Hz could help to improve the IVF outcomes partly by increasing NPY levels in the follicular fluids.

Transcriptional control of unequal cleavage in early Tubifex embryos.

Early embryos of the clitellate annelid Tubifex (oligochaete) undergo a series of unequal spiral cell divisions before the descendants of the D quadrant micromeres (cells 2d and 4d) divide bilaterally. Here, we show that inhibition of zygotic transcription by microinjection of α-amanitin (transcription inhibitor) exclusively converts unequal cleavage in cell 2d11 (granddaughter of 2d) into equal cleavage while other unequal cleavages and ensuing bilateral cleavages in cells 4d and 2d111 (great-granddaughter of 2d) all proceed in a normal fashion in the presence of this inhibitor. These results differ significantly from those reported for embryos of another clitellate annelid Helobdella (leech), in which inhibition of transcription converts bilateral (symmetric) cleavages in cells DNOPQ"' and DM" (equivalent to 2d111 and 4d) into unequal (asymmetric) cleavages while having no apparent effect on unequal cleavage in DNOPQ" (equivalent to 2d11). These differences imply distinct mechanisms for the control of the unequal-to-bilateral transition in the two clitellate annelids.

Is early embryo cleavage a factor to increase success in all types of ICSI indications?

The authors aimed to compare early embryo cleavage with pregnancy rates in intracytoplasmic sperm injection/embryo transfer (ICSI/ET) cycles due to male infertility or tubal factor infertility (TFI). 412 ICSI/embryo transfer cycles undergoing treatment for over two years were prospectively analyzed; 337 of the cycles were due to male infertility, whereas 75 suffered from tubal factors. Non-early cleaved (NEC) embryos were used for ET in 271 male factor and 67 tubal factor cycles, whereas early cleavage embryos were used for embryo transfer in 66 male factor and eight tubal factor cycles. In 66 out of 337 cycles (19.58 %) in male factor group and in eight out of 75 tubal factor cycles (10.66%), early cleavage (EC) embryos were obtained (p = 0.069). The clinical pregnancy rate was significantly elevated in EC subgroup (34.8%) compared to NEC subgroup (20.6%) (p = 0.015) in the male factor infertility group. The clinical pregnancy rate was non-significantly elevated in EC subgroup (37.5%) compared to NEC subgroup (23.8%) (p = 0.410) in the TFI group. The authors found that the implantation and pregnancy success of EC embryos vary with the therapeutic indication. The success rate would be low even with usage of EC embryos in untreated cycles of TFI.

Should we forget about embryos till day 5?

To find the way of having more and better blastocyst is essential. How to culture embryos up to blastocyst stage remains critical. Several studies show how a blastocyst score can predict the implantation potential. If that score is enough to choose the best blastocyst, as culture conditions would not be affected in these days, we would not need to check early cleavage embryos, even it could be better for the embryo development. The item that should be discussed is if it is better to evaluate or not embryos at early cleavage stages. If we do not check embryos on days 2 and 3, we should change our way to work and how to culture those embryos. First step would be to perform all embryo transfers on day 5 or 6. If we let embryos grow to blastocyst without any morphology evaluation, we should adapt several steps in our laboratory, for example we should move to a single-step culture medium or we should not do assisted hatching on day 3 embryos.

Theory about the Embryo Cryo-Treatment.

BackgroundTo create hypothesis, which can give a logical explanation related to the benefits of freezing/thawing embryos. Cryopreservation is not only a technology used for storing embryos, but also a method of embryo treatment that can potentially improve the success rate in infertile couples.MethodsFrom the analysis of multiple results in assisted reproductive technology, which have no satisfactory explanation to date, we found evidence to support a ‘therapeutic’ effect of the freezing/thawing of embryos on the process of recovery of the embryo and its subsequent implantation.ResultsFreezing/thawing is a way to activate the endogenous survival and repair responses in preimplantation embryos. Several molecular mechanisms can explain the higher success rate of ET using thawed embryos compared to fresh ET in women of advanced reproductive age, the higher miscarriage rate in cases of thawed blastocyst ET compared to thawed ET at early cleavage embryo, and the higher perinatal parameters of born children after thawed ET. Embryo thawing induces a stress. Controlled stress is not necessarily detrimental, because it generates a phenomenon that is counteracted by several known biological responses aimed to repair mitochondrial damage of membrane and protein misfolding. The term for favorable biological responses to low exposures to stress is called hormesis.ConclusionsThis thesis will summarize the role of cryopreservation in the activation of a hormetic response, preserving the mitochondrial function, improving survival, and having an impact on the process of implantation, miscarriage, and the development of pregnancy.

Clinical outcome of cycles with oocyte degeneration after intracytoplasmic sperm injection

ABSTRACTThere are variant rates of oocyte degeneration after intracytoplasmic sperm injection (ICSI) among different patients. Oocyte degeneration after ICSI may reflect the cohort of oocyte quality and subsequent embryo development capacity and clinical outcome. This retrospective study analyzed 255 cycles with at least one degenerated oocyte after ICSI (degeneration group) and 243 cycles with no degenerated oocytes after ICSI (control group). Basic characteristics like female age, body mass index, duration of infertility, hormone (FSH, LH, E2) levels on day 3 of menses, and primary infertility patient rate were similar between the two groups (p > 0.05). Total dose of gonadotropin and length of stimulation were also similar between the two groups (p > 0.05), but the degeneration group exhibited a more exuberant response to ovarian stimulation as reflected by more oocytes retrieved (p < 0.05). The number of 2PN embryos available and high quality embryos were similar between the two groups (p > 0.05), but the high quality embryo rate, early cleavage embryo rate, and available embryo rate were all statistically lower than the control group (p < 0.05). Embryo developmental kinetics seemed to be disturbed and embryo fragmentation rate increased in the degeneration group (p < 0.05). However, there was no statistical difference in the distribution of graded embryos transferred, and there were no statistical differences in the pregnancy rate, implantation rate, and abortion rate between the two groups (p > 0.05). We deduce that the presence of oocyte degeneration after ICSI may be associated with decreased embryo quality with embryo development kinetics disturbed. However, the clinical outcomes may not be affected if the premise that sufficient high quality degeneration group embryos are available for transfer.

Altered expression of BRG1 and histone demethylases, and aberrant H3K4 methylation in less developmentally competent embryos at the time of embryonic genome activation.

Epigenetics is a fundamental regulator underlying many biological functions, such as development and cell differentiation. Epigenetic modifications affect key chromatin regulation, including transcription and DNA repair, which are critical for normal embryo development. In this study, we profiled the expression of epigenetic modifiers and patterns of epigenetic changes in porcine embryos around the period of embryonic genome activation (EGA). We observed that Brahma-related gene 1 (BRG1) and Lysine demethylase 1A (KDM1A), which can alter the methylation status of lysine 4 in histone 3 (H3K4), localize to the nucleus at Day 3-4 of development. We then compared the abundance of epigenetic modifiers between early- and late-cleaving embryos, which were classified based on the time to the first cell cleavage, to investigate if their nuclear localization contributes to developmental competence. The mRNA abundance of BRG1, KDM1A, as well as other lysine demethylases (KDM1B, KDM5A, KDM5B, and KDM5C), were significantly higher in late- compared to early-cleaving embryos near the EGA period, although these difference disappeared at the blastocyst stage. The abundance of H3K4 mono- (H3K4me) and di-methylation (H3K4me2) during the EGA period was reduced in late-cleaving and less developmentally competent embryos. By contrast, BRG1, KDM1A, and H3K4me2 abundance was greater in embryos with more than eight cells at Day 3-4 of development compared to those with fewer than four cells. These findings suggest that altered epigenetic modifications of H3K4 around the EGA period may affect the developmental capacity of porcine embryos to reach the blastocyst stage. Mol. Reprod. Dev. 84: 19-29, 2017. © 2016 Wiley Periodicals, Inc.

Aneuploidy Detection and mtDNA Quantification in Bovine Embryos with Different Cleavage Onset Using a Next-Generation Sequencing-Based Protocol

Bovine embryos are now routinely used in agricultural systems as a means of disseminating superior genetics worldwide, ultimately with the aim of feeding an ever-growing population. Further investigations, common for human IVF embryos, thus have priority to improve cattle IVF, as has screening for aneuploidy (abnormal chromosome number). Although the incidence and consequences of aneuploidy are well documented in human preimplantation embryos, they are less well known for the embryos of other animals. To address this, we assessed aneuploidy levels in thirty-one 2-cell bovine embryos derived from early- and late-cleaving zygotes. Contemporary approaches ( Whole Genome Amplification and next-generation sequencing) allowed aneuploidy assessment for all chromosomes in oocytes from donors aged 4-7 years. We also quantified mitochondrial DNA (mtDNA) levels in all blastomeres assessed, thereby testing the hypothesis that they are related to levels of aneuploidy. The overall incidence of aneuploidy in this cohort of bovine embryos was 41.1% and correlated significantly with the timing of cleavage (77.8% in late-cleaving vs. 31.8% in early-cleaving embryos). Moreover, based on mtDNA sequence read counts, we observed that the median mtDNA quantity is significantly lower in late-cleaving embryos. These findings further reinforce the use of the bovine system as a model for human IVF studies.

Relationship between the mechanism of hepatitis B virus father-infant transmission and pregnancy outcome.

This study examined the relationship between the mechanism of hepatitis B virus (HBV) father-infant transmission via reproductive cells and pregnancy outcome. Abandoned in vitro fertilization (IVF) embryos of fathers with chronic HBV infection were taken as study objects. HBV mRNA in embryos was detected, and successfully transplanted embryos were followed up to determine the relationship between HBV-infected embryos and pregnancy outcome. HBV mRNA signals were detected in one embryo in the group with HBV-positive fathers; the positive rate was 1/18 (5.5%). IVF embryos of HBV-positive fathers with HBV mRNA signals were successfully implanted, but early abortion occurred. HBV mRNA was found in abandoned IVF embryos of HBV-infected fathers, which confirmed that HBV could not only enter early cleavage embryos via sperm but also replicate in embryos, resulting in HBV father-infant transmission. HBV may interfere with embryonic development and thus affect pregnancy outcome.

Inhibition of Rac1 GTPase activity affects porcine oocyte maturation and early embryo development

Mammalian oocyte asymmetric division relies on the eccentric positioning of the spindle, resulting in the polar body formation. Small signaling G protein Rac1 is a member of GTPases, which regulates a diverse array of cellular events, including the control of cell growth, cytoskeletal reorganization, and the activation of protein kinases. However, effects of Rac1 on the porcine oocyte maturation and early embryo development are not fully understood. In present study we investigated the role of Rac1 in oocyte maturation and embryo cleavage. We first found that Rac1 localized at the cortex of the porcine oocytes, and disrupting the Rac1 activities by treating with NSC 23766 led to the failure of polar body emission. In addition, a majority of treated oocytes exhibited abnormal spindle morphology, indicating that Rac1 may involve into porcine oocyte spindle formation. This might be due to the regulation of Rac1 on MAPK, since p-MAPK expression decreased after NSC 23766 treatments. Moreover, we found that the position of most meiotic spindles in treated oocytes were away from the cortex, indicating the roles of Rac1 on meiotic spindle positioning. Our results also showed that inhibition of Rac1 activity caused the failure of early embryo development. Therefore, our study showed the critical roles of Rac1 GTPase on porcine oocyte maturation and early embryo cleavage.

The antioxidative properties of S-allyl cysteine not only influence somatic cells but also improve early embryo cleavage in pigs.

In vitro cultivation systems for oocytes and embryos are characterised by increased levels of reactive oxygen species (ROS), which can be balanced by the addition of suitable antioxidants. S-allyl cysteine (SAC) is a sulfur compound naturally occurring in garlic (Allium sativum), which is responsible for its high antioxidant properties. In this study, we demonstrated the capacity of SAC (0.1, 0.5 and 1.0 mM) to reduce levels of ROS in maturing oocytes significantly after 24 (reduced by 90.33, 82.87 and 91.62%, respectively) and 48 h (reduced by 86.35, 94.42 and 99.05%, respectively) cultivation, without leading to a disturbance of the standard course of meiotic maturation. Oocytes matured in the presence of SAC furthermore maintained reduced levels of ROS even 22 h after parthenogenic activation (reduced by 66.33, 61.64 and 57.80%, respectively). In these oocytes we also demonstrated a growth of early embryo cleavage rate (increased by 33.34, 35.00 and 35.00%, respectively). SAC may be a valuable supplement to cultivation media.