Nobiletin as a novel agent to enhance porcine in vitro embryo development and quality

In vitro embryo production (IVP) is of great importance to the porcine industry, as well as for basic research and biomedical applications. Despite the large efforts made in laboratories worldwide to address suboptimal culture conditions, porcine IVP remains inefficient. Nobiletin (Nob, 5,6,7,8,3',4' hexamethoxyflavone) supplementation to in vitro culture (IVC) medium, enhances in vitro embryo development in various species. However, its impact on the quality and developmental capacity of in vitro-produced pig embryos is yet to be established. This study evaluated the effects of different concentrations (2.5 and 5 μM) of Nob during the early culture of in vitro-produced pig embryos on embryo developmental competence, mitochondrial activity, lipid content, intracellular Reactive Oxygen Species (ROS) and Glutathione (GSH) content, Total Cell Number (TCN) per blastocyst, and expression of genes related to embryo development, quality and oxidative stress. Embryos cultured in medium without Nob supplementation and in medium supplemented with 0.01 % dimethyl sulfoxide (DMSO-vehicle for Nob) constituted the Control and DMSO groups, respectively. Embryo development rates were evaluated on Days 2, 6 and 7 of IVC. Additionally, a representative group of embryos was selected to assess mitochondrial activity, lipid, ROS and GSH content (on Days 2 and 6 of IVC), TCN assessment and gene expression analyses (on Day 6 of IVC). No significant differences were observed in any of the parameters evaluated on Day 2 of IVC. In contrast, embryos cultured under the presence of Nob 2.5 showed higher developmental rates on Days 6 and 7 of IVC. In addition, Day 6 embryos showed increased mitochondrial activity, with decreased levels of ROS and GSH in the Nob 2.5 group compared to the other groups. Both Nob 2.5 and Nob 5 embryos showed higher TCN compared to the Control and DMSO groups. Furthermore, Nob 2.5 and Nob 5 upregulated the expression of Superoxide dismutase type 1 (SOD1) and Glucose-6-phosphate dehydrogenase (G6PDH) genes, which could help to counteract oxidative stress during IVC. In conclusion, the addition of Nob during the first 48 h of IVC increased porcine embryo development rates and enhanced their quality, including the upregulation of relevant genes that potentially improved the overall efficiency of the IVP system.

Extracellular vesicles-coupled miRNAs from oviduct and uterus modulate signaling pathways related to lipid metabolism and bovine early embryo development

BACKGROUND

Extracellular vesicles (EVs) present in oviductal (OF) and uterine fluid (UF) have been shown to enhance bovine embryo quality during in vitro culture by reducing lipid contents and modulating lipid metabolism-related genes (LMGs), while also influencing cell proliferation, suggesting their involvement on the regulation of different biological pathways. The regulation of signaling pathways related to cell differentiation, proliferation, and metabolism is crucial for early embryo development and can determine the success or failure of the pregnancy. Bioactive molecules within EVs in maternal reproductive fluids, such as microRNAs (miRNAs), may contribute to this regulatory process as they modulate gene expression through post-transcriptional mechanisms.

RESULTS

From the 20 differentially expressed miRNAs, 19 up-regulated in UF-EVs (bta-miR-134, bta-miR-151-3p, bta-miR-155, bta-miR-188, bta-miR-181b, bta-miR-181d, bta-miR-224, bta-miR-23b-3p, bta-miR-24-3p, bta-miR-27a-3p, bta-miR-29a, bta-miR-324, bta-miR-326, bta-miR-345-3p, bta-miR-410, bta-miR-652, bta-miR-677, bta-miR-873 and bta-miR-708) and one (bta-miR-148b) in OF-EVs. These miRNAs were predicted to modulate several pathways such as Wnt, Hippo, MAPK, and lipid metabolism and degradation. Differences in miRNAs found in OF-EVs from the early luteal phase and UF-EVs from mid-luteal phase may reflect different environments to meet the changing needs of the embryo. Additionally, miRNAs may be involved, particularly in the uterus, in the regulation of embryo lipid metabolism, immune system, and implantation. This study evaluated miRNA cargo in OF-EVs from the early luteal phase and UF-EVs from the mid-luteal phase, coinciding with embryo transit within oviduct and uterus in vivo, and its possible influence on LMGs and signaling pathways crucial for early embryo development. A total of 333 miRNAs were detected, with 11 exclusive to OF, 59 to UF, and 263 were common between both groups.

CONCLUSIONS

Our study suggests that miRNAs within OF- and UF-EVs could modulate bovine embryo development and quality, providing insights into the intricate maternal-embryonic communication that might be involved in modulating lipid metabolism, immune response, and implantation during early pregnancy.

MicroRNA-148b secreted by bovine oviductal extracellular vesicles enhance embryo quality through BPM/TGF-beta pathway

BACKGROUND

Extracellular vesicles (EVs) and their cargoes, including MicroRNAs (miRNAs) play a crucial role in cell-to-cell communication. We previously demonstrated the upregulation of bta-mir-148b in EVs from oviductal fluid of cyclic cows. This miRNA is linked to the TGF-β pathway in the cell proliferation. Our aim was to verify whether miR-148b is taken up by embryos through gymnosis, validate its target genes, and investigate the effect of miR-148b supplementation on early embryo development and quality.

METHODS

Zygotes were cultured in SOF + 0.3% BSA (Control) or supplemented with: 1 µM miR-148b mimics during: D1-D7 (miR148b) or D1-D4 (miR148b-OV: representing miRNA effect in the oviduct) or D4-D7 (miR148b-UT: representing miRNA effect in the uterus) or 1 µM control mimics was used during: D1-D7 (CMimic). Embryos at ≥ 16-cells and D7 blastocysts (BD7) were collected to examine the mRNA abundance of transcripts linked to the TGF-β pathway (TGFBR2, SMAD1, SMAD2, SMAD3, SMAD5, BMPR2, RPS6KB1, POU5F1, NANOG), total cell number (TC), trophectoderm (TE), and inner cell mass (ICM) were also evaluated. One-way ANOVA was used for all analyses.

RESULTS

We demonstrated that miR-148b can be taken up in both 16-cell embryos and BD7 by gymnosis, and we observed a decrease in SMAD5 mRNA, suggesting it's a potential target of miR-148b. Cleavage and blastocysts rates were not affected in any groups; however, supplementation of miR-148b mimics had a positive effect on TC, TE and ICM, with values of 136.4 ± 1.6, 92.5 ± 0.9, 43.9 ± 1.3 for miR148b and 135.3 ± 1.5, 92.6 ± 1.2, 42.7 ± 0.8, for miR148b-OV group. Furthermore, mRNA transcripts of SMAD1 and SMAD5 were decreased (P ≤ 0.001) in 16-cell embryos and BD7 from miR148b and miR148b-OV groups, while POU5F1 and NANOG were upregulated (P ≤ 0.001) in BD7 and TGFBR2 was only downregulated in 16-cell embryos. pSMAD1/5 levels were higher in the miR148b and miR148b-OV groups.

CONCLUSIONS

Our findings suggest that supplementation of bta-miR-148b mimics during the entire culture period (D1 - D7) or from D1 - D4 improves embryo quality and influences the TGF-β signaling pathway by altering the transcription of genes associated with cellular differentiation and proliferation. This highlights the importance of miR-148b on embryo quality and development.

Characterization and identification of extracellular vesicles-coupled miRNA profiles in seminal plasma of fertile and subfertile rabbit bucks

Seminal plasma (SP) provides essential nutrients, transport, and protection to the spermatozoa during their journey through the male and female reproductive tracts. Extracellular vesicles (EVs) are one of the main components of the SP with several biomolecular cargoes, including miRNAs, that can influence spermatozoa functions and interact with the cells of the female reproductive tract. This study aimed to isolate, characterize, and identify the miRNA expression profiles in the SP-EVs isolated from fertile (F) and subfertile (S) rabbit bucks that could serve as fertility biomarkers. In this study, the methods to isolate and identify EVs including exosomes, from SP of 3 F and S bucks have been developed. Ultracentrifugation and size exclusion chromatography analysis were using to isolate EVs from SP of F and S males that were qualitative and quantitively characterised using transmission electron microscopy, nanoparticle tracking analysis and western blotting. In addition, total RNA, including miRNA, was isolated, sequenced and identified from SP-EVs samples. Different SP-EVs concentrations (8.53 × 1011 ± 1.04 × 1011 and 1.84 × 1012 ± 1.75 × 1011 particles/mL of SP; P = 0.008), with a similar average size (143.9 ± 11.9 and 115.5 ± 2.4 nm; P = 0.7422) in F and S males, respectively was observed. Particle size was not significantly correlated with any kinetic parameter. The concentration of SP-EVs was positively correlated with the percentage of abnormal forms (r = 0.94; P < 0.05) and with the percentage of immotile spermatozoa (r = 0.88; P < 0.05). Small-RNA-seq analysis identified a total of 267 and 244 expressed miRNAs in the F and S groups, respectively. Two miRNAs (let-7b-5p and let-7a-5p) were the top most abundant miRNAs in both groups. Differential expression analysis revealed that 9 miRNAs including miR-190b-5p, miR-193b-5p, let-7b-3p, and miR-378-3p, and another 9 miRNAs including miR-7a-5p, miR-33a-5p, miR-449a-5p, and miR-146a-5p were significantly up- and downregulated in the F compared to the S group, respectively. The SP from F and S rabbit males contains EVs with different miRNA cargo correlated with spermatogenesis, homeostasis, and infertility, which could be used as biomarkers for male fertility and potential therapies for assisted reproductive technologies.

Oocyte-cumulus cells crosstalk: New comparative insights

Mammalian follicles are constituted of a complex structure composed of several layers of granulosa cells surrounding the oocyte and of theca cells that reside beneath its basement membrane. During folliculogenesis, granulosa cells separate into two anatomically and functionally distinct sub-types; the mural cells lining the follicle wall and the oocyte-surrounding cumulus cells, i.e. those in intimate metabolic contact with the oocyte. The cumulus cells connecting with the oocyte have trans-zonal cytoplasmic projections which, penetrating the zona pellucida, form the cumulus-oocyte complex. The connections through gap junctions allow the transfer of small molecules between oocyte and cumulus cells, such as ions, metabolites, and amino acids necessary for oocyte growth, as well as small regulatory molecules that control oocyte development. The bi-directional communication between the oocyte and cumulus cells is crucial for the development and functions of both cell types. Our current knowledge of the relationship between the oocyte and its surrounding cumulus cells continues to change as we gain a greater understanding of factors regulating oocyte development and folliculogenesis. This review will mainly focus on the reciprocal interaction between oocytes and cumulus cells during the latter stages of follicle development i.e. through antral development to periovulatory events including oocyte maturation, expansion, and degradation of the cumulus matrix.

Acquisition of fertilization competence in guinea pig spermatozoa under different capacitation protocols

Guinea pig in vitro fertilization (IVF) are poorly developed due to the limited accessibility to oocytes and the lack of an efficient method of sperm capacitation. Thus, we aimed to evaluate different capacitation protocols that we validated through sperm analysis and using heterologous (He) IVF with zona-intact bovine oocytes. Spermatozoa of guinea pigs were collected and processed separately by 4 different protocols: A) Spermatozoa were obtained by flushing the lumen of one cauda epididymis and incubated in a minimal culture medium (MCM); B) One epididymis was placed in a prewarmed of M2 medium and gently minced with fine scissors. Spermatozoa were incubated in a modified human tubal fluid medium (HTF). In both protocols, the spermatozoa were capacitated at 37 °C under an atmosphere of 5% CO2 for 2 h. In the protocols C and D, the spermatozoa were collected by flushing the lumen of the cauda epididymis and selected by commercial density gradient Bovipure® (Nidacon Laboratories AB, Göthenborg, Sweden), according to the manufacturer's instructions. Then for Protocol C) spermatozoa were incubated in MCM medium supplemented with 10 mg/mL heparin (MCM-Hep); while for Protocol D) spermatozoa were incubated in FERT medium supplemented 10 mg/mL heparin (FERT-Hep). Incubation of C and D protocols were performed at 38.5 °C under an atmosphere of 5% CO₂ for 2 h. Capacitation protocols C and D showed a higher percentage of viability, total and hyperactive-like motility, and acrosome reaction compared to protocols A and B. For this reason, protocols C and D were used for further He-IVF analysis. Guinea pig sperm and matured zona-intact bovine oocytes were co-incubated at 5% CO₂ and 38.5 °C. Sperm-oocyte interaction was assessed at 2.5 h post-insemination (hpi) and pronuclear formation (PrF) were evaluated at 18, 20, 22, 24 and 26 hpi, while the cleavage rate was evaluated at 48 hpi. In protocol D, PrF was significantly higher than in protocol C (P ≤ 0.05) at every time point evaluated. Also, the cleavage rate at 48 hpi was higher (P ≤ 0.05) in He-IVF protocol D (69.8 ± 1.7%) compared to He-IVF protocol C (49.1 ± 1.1%). In conclusion, we determined the most adequate sperm capacitation conditions for guinea pig that allow zona-intact bovine oocyte penetration and lead to hybrid embryo formation, suggesting that these conditions could be optimal to develop IVF in guinea pigs.

Bull spermatozoa selected by thermotaxis exhibit high DNA integrity, specific head morphometry, and improve ICSI outcome

BACKGROUND

Sperm migration by thermotaxis is a guidance mechanism that operates along the oviduct and it has proved to be a valid method for selecting spermatozoa with low DNA fragmentation (SDF) in mice, humans, and stallions. This study aimed to analyse if bull spermatozoa could be selected by thermotaxis and to assess their quality in terms of SDF as well as determine the presence of a specific sperm subpopulation based on sperm morphometry and assess their fertilizing capacity by ICSI.

METHODS

We used frozen-thawed sperm from 6 bulls and sperm selection by thermotaxis was performed with TALP medium supplemented with 25 mmol/L of HEPES and 5 mmol/L of caffeine. In these conditions, sperm selection was achieved, obtaining a net thermotaxis of 3.6%. Subsequently, we analysed the SDF of the migrated and not-migrated spermatozoa using the neutral COMET assay, and we evaluated the size of the sperm head using Hemacolor® staining with Motic Images Plus 3 software. Additionally, migrated and not-migrated spermatozoa by thermotaxis were used to fertilize bovine in vitro matured (IVM) oocytes by ICSI, a very inefficient procedure in cattle that is only successful when the oocyte is artificially activated.

RESULTS

The results showed lower SDF (χ², P < 0.001, 13.3% reduction, n = 8) and lower head size parameters (length and width, P < 0.01; and perimeter and area, P < 0.001; n = 4) in those spermatozoa migrated in comparison to those not-migrated. The distribution of sperm subpopulations structure varied between groups, highlighting cluster 2, characterized by spermatozoa with small head size, and high ellipticity and elongated heads, as the most abundant in the thermotaxis migrated group. When performed ICSI (without oocyte artificial activation) with the thermotactic sperm, the blastocyst rate was 32.2% ± 9.3% in the group microinjected with the thermotactic spermatozoa vs. 8.3% ± 7.8% in the group of not-migrated sperm (χ², P < 0.05).

CONCLUSION

Our results showed that bull sperm selection by thermotaxis has a much higher DNA integrity, small and elongated head size parameters, and different sperm subpopulation structure than the not-selected spermatozoa. Additionally, we evidenced that thermotactic spermatozoa improve ICSI success rates.

Extracellular vesicles from oviductal and uterine fluids supplementation in sequential in vitro culture improves bovine embryo quality

Background

In vitro production of bovine embryos is a well-established technology, but the in vitro culture (IVC) system still warrants improvements, especially regarding embryo quality. This study aimed to evaluate the effect of extracellular vesicles (EVs) isolated from oviductal (OF) and uterine fluid (UF) in sequential IVC on the development and quality of bovine embryos. Zygotes were cultured in SOF supplemented with either BSA or EVs-depleted fetal calf serum (dFCS) in the presence (BSA-EV and dFCS-EV) or absence of EVs from OF (D1 to D4) and UF (D5 to D8), mimicking in vivo conditions. EVs from oviducts (early luteal phase) and uterine horns (mid-luteal phase) from slaughtered heifers were isolated by size exclusion chromatography. Blastocyst rate was recorded on days 7–8 and their quality was assessed based on lipid contents, mitochondrial activity and total cell numbers, as well as survival rate after vitrification. Relative mRNA abundance for lipid metabolism-related transcripts and levels of phosphorylated hormone-sensitive lipase (pHSL) proteins were also determined. Additionally, the expression levels of 383 miRNA in OF- and UF-EVs were assessed by qRT-PCR.

Results

Blastocyst yield was lower (P < 0.05) in BSA treatments compared with dFCS treatments. Survival rates after vitrification/warming were improved in dFCS-EVs (P < 0.05). EVs increased (P < 0.05) blastocysts total cell number in dFCS-EV and BSA-EV compared with respective controls (dFCS and BSA), while lipid content was decreased in dFCS-EV (P < 0.05) and mitochondrial activity did not change (P > 0.05). Lipid metabolism transcripts were affected by EVs and showed interaction with type of protein source in medium (PPARGC1B, LDLR, CD36, FASN and PNPLA2, P < 0.05). Levels of pHSL were lower in dFCS (P < 0.05). Twenty miRNA were differentially expressed between OF- and UF-EVs and only bta-miR-148b was increased in OF-EVs (P < 0.05).

Conclusions

Mimicking physiological conditions using EVs from OF and UF in sequential IVC does not affect embryo development but improves blastocyst quality regarding survival rate after vitrification/warming, total cell number, lipid content, and relative changes in expression of lipid metabolism transcripts and lipase activation. Finally, EVs miRNA contents may contribute to the observed effects.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-022-00763-7.

Neutrophil to lymphocyte ratio in the prediction of coagulopathy in traumatic brain injury

Aim: Traumatic brain injury (TBI) is a public health issue of increasing incidence. Coagulopathy after TBI is a frequent event, associated with a poor prognosis, and biomarkers that could predict coagulopathy occurrence are needed. The neutrophil-to-lymphocyte ratio (NLR) is useful as a cost-effective biomarker to assess prognosis and the need for cranial computed tomography in patients with mild TBI. As no study has yet evaluated the association of NLR with coagulopathy, we investigated whether the NLR at presentation could predict coagulopathy occurrence after TBI. Materials & methods: A retrospective study was conducted of patients aged >18 years who attended the emergency department (ED) with TBI, over a 3-year period. We included all patients for whom the NLR at presentation was available, and who underwent a brain CT scan. Results: The study included 173 patients (mean age 57.4 ± 21.1 years) with TBI, the most frequent cause of which was a fall. According to the Glasgow Coma Scale, 37 patients had severe TBI, 19 moderate and 117 mild TBI and 40 patients (23.1%) developed coagulopathy. Their mean NLR was 7.5 ± 6.7. Using receiver operating characteristic curve analysis, a cut-off value of 4.2 for NLR had 87.5% sensitivity and 52.9% specificity for predicting coagulopathy occurrence. Conclusion: Coagulopathy occurs frequently after TBI. This study investigated the value of NLR as a biomarker to predict coagulopathy occurrence, and concluded that NLR might be a novel and inexpensive biomarker for decision making in the management of TBI. Combination of NLR with other low-cost biomarkers and the clinical findings might further increase accuracy in the prediction of coagulopathy.

Role of reproductive fluids and extracellular vesicles in embryo&#x2013;maternal interaction during early pregnancy in cattle

The coordinated interaction between the developing embryo and the maternal reproductive tract is essential for the establishment and maintenance of pregnancy in mammals. An early cross-talk is established between the oviduct/uterus and the gametes and embryo. This dialogue will shape the microenvironment in which gamete transport, fertilisation, and early embryonic development occur. Due to the small size of the gametes and the early embryo relative to the volume of the oviductal and uterine lumina, collection of tissue and fluid adjacent to these cells is challenging in cattle. Thus, the combination of in vivo and in vitro models seems to be the most appropriate approach to better understand this fine dialogue. In this respect, the aim of this review is to summarise the recent findings in relation to gamete/embryo-maternal interaction during the pre-elongation period.

Characterization and profiling analysis of bovine oviduct and uterine extracellular vesicles and their miRNA cargo through the estrous cycle

Extracellular vesicles (EVs) found in various biological fluids and particularly in reproductive fluids, have gained considerable attention for their possible role in cell- to- cell communication. Among, the different bioactive molecules cargos of EVs, MicroRNAs (miRNAs) are emerging as promising diagnostic biomarkers with high clinical potential. Aiming to understand the roles of EVs in bovine reproductive tract, we intended to characterize and profile the EVs of oviduct and uterine fluids (OF-EVs, UF-EVs) and their miRNA across the estrous cycle. Nanoparticle tracking analysis and transmission electron microscopy confirmed the existence of small EV population in OF and UF at all stages, (size between 30 and 200 nm; concentration: 3.4 × 10¹⁰  EVs/ml and 6.0 × 10¹⁰  EVs/ml for OF and UF, respectively, regardless of stage). The identification of EV markers (CD9, HSP70, and ALIX proteins) was confirmed by western blot. The miRNA analysis revealed the abundance of 310 and 351 miRNAs in OF-EVs and UF-EVs, respectively. Nine miRNAs were differentially abundant in OF-EVs between stages of the cycle, eight of them displayed a progressive increase from S1 to S4 (p < .05). In UF-EVs, a total of 14 miRNAs were differentially abundant between stages. Greater differences were observed between stage 1 (S1) and stage 3 (S3), with 11 miRNAs enriched in S3 compared to S1. Functional enrichment analysis revealed the involvement of these miRNAs in relevant pathways such as cell signaling, intercellular junctions, and reproductive functions that may be implicated in oviduct and uterus modulation across the cycle, but also in their preparation for embryo/conceptus presence and development.

Nobiletin-induced partial abrogation of deleterious effects of AKT inhibition on preimplantation bovine embryo development in vitro

During preimplantational embryo development, PI3K/AKT regulates cell proliferation and differentiation and nobiletin modulates this pathway to promote cell survival. Therefore, we aimed to establish whether, when the AKT cascade is inhibited using inhibitors III and IV, nobiletin supplementation to in vitro culture media during the minor (2 to 8-cell stage, MNEGA) or major (8 to 16-cell stage, MJEGA) phases of EGA is able to modulate the development and quality of bovine embryos. In vitro zygotes were cultured during MNEGA or MJEGA phase in SOF + 5% FCS or supplemented with: 15 μM AKT-InhIII; 10 μM AKT-InhIV; 10 μM nobiletin; nobiletin+AKT-InhIII; nobiletin+AKT-InhIV; 0.03% DMSO. Embryo development was lower in treatments with AKT inhibitors, while combination of nobiletin with AKT inhibitors was able to recover their adverse developmental effect and also increase blastocyst cell number. The mRNA abundance of GPX1, NFE2L2, and POU5F1 was partially increased in 8- and 16-cell embryos from nobiletin with AKT inhibitors. Besides, nobiletin increased the p-rpS6 level whether or not AKT inhibitors were present. In conclusion, nobiletin promotes bovine embryo development and quality and partially recovers the adverse developmental effect of AKT inhibitors which infers that nobiletin probably uses another signalling cascade that PI3K/AKT during early embryo development in bovine.

Culture Medium and Sex Drive Epigenetic Reprogramming in Preimplantation Bovine Embryos

Assisted reproductive technologies impact transcriptome and epigenome of embryos and can result in long-term phenotypic consequences. Whole-genome DNA methylation profiles from individual bovine blastocysts in vivo- and in vitro-derived (using three sources of protein: reproductive fluids, blood serum and bovine serum albumin) were generated. The impact of in vitro culture on DNA methylation was analyzed, and sex-specific methylation differences at blastocyst stage were uncovered. In vivo embryos showed the highest levels of methylation (29.5%), close to those produced in vitro with serum, whilst embryos produced in vitro with reproductive fluids or albumin showed less global methylation (25-25.4%). During repetitive element analysis, the serum group was the most affected. DNA methylation differences between in vivo and in vitro groups were more frequent in the first intron than in CpGi in promoters. Moreover, hierarchical cluster analysis showed that sex produced a stronger bias in the results than embryo origin. For each group, distance between male and female embryos varied, with in vivo blastocyst showing a lesser distance. Between the sexually dimorphic methylated tiles, which were biased to X-chromosome, critical factors for reproduction, developmental process, cell proliferation and DNA methylation machinery were included. These results support the idea that blastocysts show sexually-dimorphic DNA methylation patterns, and the known picture about the blastocyst methylome should be reconsidered.

Asynchrony between the early embryo and the reproductive tract affects subsequent embryo development in cattle

The aim of this study was to determine the effect of maternal-embryonic asynchrony in the reproductive tract (oviduct and uterus) on subsequent embryo development in cattle. Fifty Day 1invitro-produced zygotes were transferred endoscopically into the oviduct ipsilateral to the corpus luteum of heifers (n=40) that were either synchronous with the embryos (Day 1 after ovulation) or asynchronous and ahead of the embryo (Day 3 after ovulation). A subset of heifers was killed in a commercial abattoir 3, 6 or 14 days after embryo transfer. Location within the reproductive tract, developmental stage and the quality of embryos were recorded. Transfer of embryos to an advanced (asynchronous) oviduct resulted, on Day 4, in fewer embryos at the expected location (oviduct), and a greater number of degenerated and retarded embryos with a lower total cell number than for embryos in the synchronous group. Similarly, on Day 7, asynchrony led to a greater number of degenerated and retarded embryos compared with the synchronous group. Total embryo cell number was similar among groups. Although Day 15 conceptuses were longer following asynchronous transfer, only 50% of the asynchronous heifers yielded conceptuses, compared with 100% in the synchronous group. In conclusion, asynchrony between the developing embryo and the reproductive tract has a negative effect on embryo development.

56 Nobiletin affects gene expression profiles of the ERK1/2 pathway in bovine embryos produced invitro

During embryo development the embryonic genome activation (EGA) is one of the most important events and in bovine embryos it occurs at the 8- to 16-cell stage. Invitro embryo production increases the levels of reactive oxygen species (ROS), which leads to the low quality of the produced blastocysts, possibly by affecting EGA. Nobiletin is an antioxidant that affects cell cycle regulation (Huang et al. 2016 Evid. Based. Complement. Alternat. Med. 2016, 2918796, https://doi.org/10.1155/2016/2918796). Therefore, we aimed to evaluate the effect of nobiletin supplementation, in two key periods of early embryo development, on blastocyst yield and expression of selected genes of the ERK1/2 pathway and oxidative stress on produced embryos. Invitro zygotes were cultured in synthetic oviductal fluid (SOF) with 5% fetal calf serum (control, C); C with 5 or 10µM nobiletin (MedChemExpress) (N5, N10); or C with 0.03% dimethyl sulfoxide (CDMSO; vehicle for nobiletin dilution) during the minor (21–54h post-insemination (hpi): 2- to 8-cell; MNEGA; 12 replicates) or major (54–96 hpi: 8- to 16-cell; MJEGA; 10 replicates) phase of EGA. The speed of development was considered and embryos that reached ≥8 cells at 54 hpi from MNEGA phase and ≥16 cells at 96 hpi from MJEGA phase, were selected and further cultured in control medium until Day 7. Embryos at ≥8 cell (MNEGA), ≥16 cell (MJEGA) stage, and Day 7 blastocysts from both periods were snap-frozen in liquid N2 for gene expression analysis (3 pools of 10 embryos/treatment). The expression of genes related to ERK1/2 pathway (H3–3B, H3–3A, NFE2L2) and oxidative stress (GPX1) were measured by quantitative PCR; H2AFZ and ACTB were used as housekeeping genes. Statistical analysis was assessed by one-way ANOVA. At 54 hpi, irrespective of nobiletin supplementation, no differences were found in the proportion of embryos that reached the 8-cell stage between groups in both phases (≈60%). At 96 hpi, nobiletin during MJEGA showed a higher proportion of embryos reaching the 16-cell stage than control groups (≈70% vs. ≈60%, respectively; P&lt;0.001). Blastocyst yield for MNEGA and MJEGA was higher (P&lt;0.001) for N5 (40.0±0.8% and 46.7±0.8%) and N10 (41.0±0.9% and 54.5±1.1%) compared with C (32.0±0.6% and 38.4±1.1%) and CDMSO (31.2±0.4% and 35.8±1.0%) groups, while N10 was higher (P&lt;0.05) compared to N5 group in MJEGA. The expression of H3–3B and H3–3A were higher (P&lt;0.05) in 8-cell embryos from N5 and N10 groups during MNEGA; while in 16-cell embryos, H3–3B and NFE2L2 were higher (P&lt;0.05) only in the N10 group compared with both controls during MJEGA. GPX1 was upregulated in nobiletin-supplemented groups from both phases (8- and 16-cell embryos and blastocysts) compared with controls (P&lt;0.05). In conclusion, nobiletin supplementation during minor or major EGA has a positive effect in pre-implantation embryo development and modifies the transcription of cell cycle and oxidative stress genes in early embryos. These benefits can be attributed to its bioactivity and indicate that it might be a tool to overcome EGA and ROS disorders in bovine invitro-produced embryos.This research was funded by MINECO-Spain AGL2015-70140-R, PID2019-111641RB-I00, RTI2018-093548-B-I00; SENESCYT-Ecuador; FAPESP-Brazil 2017/20339-3, CNPq-Brazil 304276/2018-9.

36 Analysis of miRNA content of oviduct and uterine extracellular vesicles across the bovine estrous cycle

With the aim of investigating the possible hormonal regulatory effect of the oestrous cycle on miRNA content in the extracellular vesicles (EVs) of bovine oviducal and uterine fluids (OF, UF), we performed a bioinformatic analysis of these miRNAs, their target genes, and their biological pathways. Reproductive tracts were collected from slaughtered heifers and selected according to their corpus luteum morphology, corresponding to the 4 stages of the oestrous cycle (n=5 per stage; S1: days 1 to 4, S2: days 5–10, S3: days 11–17, S4: days 18–20) and transported to the laboratory on ice. EVs were obtained by size exclusion chromatography (PURE-EVs-Hansa Biomed) from the flushing of 1.2mL and 2.5mL of OF and UF, respectively. To concentrate the EVs, they were ultracentrifuged and suspended in 100µL of PBS. Total RNA extraction was obtained from 70µL of the previous pellet, using miRNeasy Mini Kit (Qiagen). Then, 100 to 200ng of the obtained RNA was reverse transcribed using miScript II RT Kit (Qiagen). MicroRNA (miRNA) expression profiling was done by primer-based real-time quantitative PCR of 383 mature miRNA sequences. Possible miRNA target genes and their biological pathways were predicted using the miRWalk database. Among EV miRNAs in OF, bta-miR-130a, bta-miR-382, and bta-miR-1291 were the most abundant at all stages of the oestrous cycle, displaying a significantly progressive increase from stages 1 to 4 (P&lt;0.05). In UF, bta-miR-17-5p, bta-miR-206, bta-miR-22-5p, bta-miR-502a, and bta-miR-503-3p were the most abundant at all stages of the cycle, showing greater differences between S1 and S3 (P&lt;0.05). Other miRNAs were exclusively present in a specific stage of the oestrous cycle in OF: bta-miR-21-5p (S1), bta-miR-146a (S2), bta-miR-128 (S3), and bta-miR-147 (S4). In UF, bta-miR-218 (S1), bta-miR-208b (S2), bta-miR-340 (S3), and bta-miR-335 (S4) were found. Table 1 presents some of these miRNAs, their predicted target genes, and functional pathways. In conclusion, this study highlights the effect of the oestrous cycle on miRNAs contained in the EVs of OF and UF. These miRNAs are related to relevant biological pathways implicated in oviduct and uterus modulation across the cycle, but they may also prepare those organs for embryo/conceptus presence and development. Table 1. Micro (mi)RNAs of oviductal (OF) and uterine fluid (UF) extracellular vesicles (EVs), their target genes, and biological pathways Reproductive fluid miRNAs Target genes Target pathways OF bta-miR-130a BMPR2, SMAD5, SMAD4 BMP signalling bta-miR-1291 SLC2A1 Glucagon signalling bta-miR-21–5p LIF Pluripotency stem cells regulation UF bta-miR-17-5p STAT3 Prolactin signalling bta-miR-206 ESR1 Oestrogen signalling bta-miR-340 HRAS Ras/MAPK/ERK signalling (embryo implantation) This research was funded by MINECO-Spain AGL2015-70140-R, PID2019-111641RB-I00, RTI2018-093548-B-I00; SENESCYT-Ecuador (YNC); FAPESP-Brazil 2017/20339-3 (CLVL), 2014/22887-0 (JCS), 2019/04981-2 (RM); CNPq-Brazil 304276/2018-9, 420152/2018-0 (CLVL).

Isolation, Characterization, and MicroRNA Analysis of Extracellular Vesicles from Bovine Oviduct and Uterine Fluids

Intercellular communication can be carried out by circulating systemic and/or locally released extracellular vesicles (EVs), produced by nearly every cell type and tissue, and are involved in physiological and pathological processes. In recent years, EVs have been identified in reproductive tissues, such as oviduct and uterus, and have been shown to be related to several events important for reproductive success. The understanding of their functions in reproduction has important implications for assisted reproductive technologies, for the treatment of infertility in humans and improvement of reproduction efficiency in animals. To study such EVs, it is necessary to isolate and concentrate them from fluid samples, which in the case of reproductive tissues, are usually of limited volume. Several methods for EV isolation are available such as chromatography, ultracentrifugation, polymer-based precipitation, and immunoaffinity.Outcomes can be variable in terms of the amount and quality of isolated EVs, due to the type of isolation method. The choice of method, or a different combination of methods, may depend on the type of sample and scientific question to be addressed in a given study. In this chapter, we describe a method for isolation of EVs from bovine oviductal and uterine fluids for use in functional studies. The method combines size exclusion chromatography and ultracentrifugation. We also describe the different protocols for characterization of isolated EVs (transmission electron microscopy, nanoparticle tracking analysis, and western blot), as well as the isolation of RNA content in EVs, and their miRNAs profiling for functional studies.

52 Extracellular vesicles from oviduct and uterus in sequential invitro culture affects mitochondrial activity and lipid metabolism transcripts in bovine embryos

Oviducal fluid (OF) and uterine fluid (UF) improve the quality of embryos during invitro culture, and their extracellular vesicles (EV) may be involved in such an effect. We aimed to evaluate the effect of EV from OF and UF in sequential invitro culture on the development and quality of bovine embryos. Zygotes were cultured in synthetic oviduct fluid supplemented either with 3mg mL−1 BSA (n=1584) or 5% EV-depleted fetal calf serum (dFCS, n=1594) in absence or presence (BSAEV, n=1853 and dFCSEV, n=1473) of 3×105 EV mL−1 from OF (Day 1 to Day 4) and UF (Day 5 to Day 8), mimicking invivo conditions. EV from oviducts (early luteal phase) and uterine horns (mid luteal phase) from slaughtered heifers were isolated by size exclusion chromatography; size and concentration were assessed by nanotracking analysis (NTA) and morphology by transmission electron microscopy (TEM). Blastocyst rate was recorded on Days 7–8 and their quality was assessed for mitochondrial activity by staining with Mitotracker Deep Red (ThermoFisher Scientific), survival rate after vitrification/warming by invitro culture for up to 72h, and relative mRNA abundance of lipid metabolism-related transcripts by quantitative PCR. Housekeeping genes were H2AFZ and ACTB. Data were analysed by one-way ANOVA and Tukey test. TEM confirmed the presence and morphology of EVs, and NTA indicated mode size and concentration of particles (137.2 and 151.2 nm; 2.97×1010 and 7.98×1010 particles mL−1, for OF and UF, respectively). Blastocyst yield was lower (P&lt;0.05) in BSA groups compared with dFCS groups (BSA: 16.2±1.5 and 31.0±1.9; BSAEV: 14.1±1.6 and 26.2±2.0% vs. dFCS: 30.5±2.0 and 40.6±2.4; dFCSEV: 31.1±2.5 and 39.8±2.7%, Day 7 and Day 8, respectively), irrespective of EV supplementation. Blastocyst mitochondrial activity was increased (P&lt;0.05) by EV in dFCSEV compared with the other groups. No differences in survival rate after vitrification/warming were found (range at 72 h: 67.1±8.1 to 87.8±5.7%). PPARGC1B was downregulated and ACC upregulated by EV, irrespective of protein source in medium (P&lt;0.05). In contrast, EV affected some transcripts depending on the protein source in the medium (CD36 upregulated in dFCSEV, downregulated in BSAEV; PLIN2 downregulated in dFCSEV and ATGL downregulated in BSAEV, P&lt;0.05). In conclusion, mimicking physiological conditions using EV from OF and UF in sequential IVC does not affect development but improves embryo quality by increasing blastocysts’ mitochondrial activity and favours the expression of specific lipid metabolism transcripts. Functional effects of EV may be influenced by the protein source in the medium. This research was funded by MINECO-Spain AGL2015-70140-R, PID2019-111641RB-I00, RTI2018-093548-B-I00; YN Cajas, SENESCYT-Ecuador; CLV Leal, FAPESP-Brazil 2017/20339-3, CNPq-Brazil 304276/2018-9.

Senescence and Apoptosis During in vitro Embryo Development in a Bovine Model

According to the World Health Organization, infertility affects up to 14% of couples under reproductive age, leading to an exponential rise in the use of assisted reproduction as a route for conceiving a baby. In the same way, thousands of embryos are produced in cattle and other farm animals annually, leading to increased numbers of individuals born. All reproductive manipulations entail deviations of natural phenotypes and genotypes, with in vitro embryo technologies perhaps showing the biggest effects, although these alterations are still emerging. Most of these indications have been provided by animal models, in particular the bovine species, due to its similarities to human early embryo development. Oocytes and embryos are highly sensitive to environmental stress in vivo and in vitro. Thus, during in vitro culture, a number of stressful conditions affect embryonic quality and viability, inducing subfertility and/or long-term consequences that may reach the offspring. A high proportion of the embryos produced in vitro are arrested at a species-specific stage of development during the first cell divisions. These arrested embryos do not show signs of programmed cell death during early cleavage stages. Instead, defective in vitro produced embryos would enter a permanent cell cycle arrest compatible with cellular senescence, in which they show active metabolism and high reactive oxygen species levels. Later in development, mainly during the morula and blastocyst stages, apoptosis would mediate the elimination of certain cells, accomplishing both a physiological role in to balancing cell proliferation and death, and a pathological role preventing the transmission of damaged cells with an altered genome. The latter would acquire relevant importance in in vitro produced embryos that are submitted to stressful environmental stimuli. In this article, we review the mechanisms mediating apoptosis and senescence during early embryo development, with a focus on in vitro produced bovine embryos. Additionally, we shed light on the protective role of senescence and apoptosis to ensure that unhealthy cells and early embryos do not progress in development, avoiding long-term detrimental effects.

Anti-Mullerian hormone concentrations are inversely associated with subclinical atherosclerosis in premenopausal women

Background

Anti-Müllerian hormone (AMH) constitutes a marker of ovarian reserve and appears to have a predictive role regarding the time of menopause. Moreover, AMH is associated with adverse cardiac events. History of premature menopause and early onset of menopause have been associated with increased risk of cardiovascular (CV) disease. In addition, menopausal transition and duration of menopause have been associated with increased burden of subclinical atherosclerosis. However, the association between AMH as a marker of female reproductive age with atherosclerosis in premenopausal women is currently unknown.

Purpose

To investigate whether AMH concentrations are associated with markers of early atherosclerosis in healthy, normally menstruating women.

Methods

In a cross-sectional study, vascular structure and function were assessed by measurement of carotid and femoral intima-media thickness (IMT), lipid profile and serum AMH concentrations were assessed. Exclusion criteria were clinically overt CV disease, abnormal ovulatory cycles, polycystic ovarian syndrome, acute infection or chronic inflammatory disease, risk factors for CV disease and any medication

Results

Seventy premenopausal women, aged 32.7±6.5 years, were included. Mean AMH levels were lower in smokers than in non-smokers and negatively associated with total cholesterol (TC) levels. An inverse association between mean AMH concentrations and IMT in all segments was observed. No correlation with other markers of subclinical atherosclerosis or traditional CV risk factors was found. After multi-variable adjustment for traditional CV risk factors, the association between AMH concentrations combined IMT and carotid bulb IMT, remained significant.

Conclusions

In healthy, normally ovulating women, low AMH concentrations are associated with an adverse lipid profile and subclinical atherosclerosis, independently of traditional CV risk factors. This finding suggest a role of decreased follicular reserve with atherosclerotic disease.

Funding Acknowledgement

Type of funding source: None

Fertilizing capacity of vitrified stallion sperm assessed utilizing heterologous IVF after different semen warming procedures

The aim of this study was to evaluate the fertilizing capacity of frozen or vitrified stallion sperm after assessing different warming procedures. In Experiment 1, different warming procedures were compared after sperm vitrification: immersion in extender at 43 °C (C), or in a water bath at 37 °C/30 s (W37), 43 °C/10 s (W43) or 60 °C/5 s (W60). With the W60 treatment, there were greater values (P < 0.05) for VCL (83.93 ± 3.6 μm/s) and ALH (3.00 ± 0.2 μm) than freezing and with the C group, and greater values (P < 0.001) for PM (35.33 ± 2.5 %) than with the W43 treatment. In Experiment 2, the fertilizing capacity of vitrified and frozen sperm was assessed utilizing heterologous IVF procedures, using cattle oocytes. Vitrification resulted in greater values (P < 0.05) than freezing for the number of bound sperm (1.36 ± 0.3 and 0.69 ± 0.2, respectively). There were no differences between frozen or vitrified sperm in pronuclear formation (26 hours post-insemination - hpi; 14.08 ± 4.2 % and 22.78 ± 4.8 %, respectively) or cleavage rate (32.77 ± 4.3 % and 39.66 ± 4.6 %, respectively). In conclusion, vitrified stallion sperm warmed in a water bath at 60 ºC had the capacity to penetrate cattle oocytes, leading to pronuclear formation and hybrid embryo cleavage after heterologous IVF.

Inhibiting diacylglycerol acyltransferase-1 reduces lipid biosynthesis in bovine blastocysts produced in vitro

Diacylglycerol acyltransferase-1 (DGAT1) is one of the DGAT enzymes that catalyzes the final step in the synthesis of triacylglycerol, which is a major component of the lipid droplets in embryos. Intracellular lipids accumulated in embryos produced in vitro have been associated with reduced cryotolerance and quality. The objective of the present study was to investigate the influence of DGAT1 inhibition on embryo development, quality, and post-vitrification survival, in addition to expression profiles of selected lipid metabolism-regulating and oxidative stress genes. Bovine cumulus-oocyte complexes were matured and fertilized in vitro and were cultured in synthetic oviduct fluid (SOF) supplemented with 5% fetal calf serum (FCS) alone (Control) or with 1, 5, 10 or 50 μM DGAT1 inhibitor (A922500®; D1, D5, D10, and D50, respectively) or 0.1% dimethyl sulfoxide (CDMSO: vehicle for DGAT1 inhibitor dilution) from 54 h post-insemination until Day 8 post insemination. No differences were found in blastocyst yield on days 7 and 8 in Control, CDMSO, D10, and D50 groups. Embryos cultured with 10 or 50 μM DGAT1 inhibitor had greater mitochondrial activity (P < 0.01), and increased number of cells (P < 0.05), while the cytoplasmic lipid content was reduced (P < 0.01), the latter associated with altered expression profiles of selected genes regulating lipid metabolism or genes related with oxidative stress (transcript abundance increased for SLC2A1 and SLC2A5 and decreased for DGAT1 and GPX1). Importantly, the survival rate of blastocysts produced with 10 μM DGAT1 was higher than that of Control, CDMSO and D50 groups at 72 h after vitrification and warming (73.8 vs 57.1, 55.9 and 56.1%, respectively, P < 0.001). In conclusion, inhibition of DGAT1 synthesis in bovine embryos produced in vitro abrogates the negative effect of FCS by decreasing their lipid content, increasing mitochondria activity and improving embryo cryotolerance, as well as favoring the expression of lipid metabolism regulating and oxidative stress-related transcripts.

Gene expression and metabolic response of bovine oviduct epithelial cells to the early embryo

During its journey through the oviduct, the bovine embryo may induce transcriptomic and metabolic responses, via direct or indirect contact, from bovine oviduct epithelial cells (BOECs). An in vitro model using polyester mesh was established, allowing the study of the local contact during 48 h between a BOEC monolayer and early embryos (2- or 8-cell stage) or their respective conditioned media (CM). The transcriptomic response of BOEC to early embryos was assessed by analyzing the transcript abundance of SMAD6, TDGF1, ROCK1, ROCK2, SOCS3, PRELP and AGR3 selected from previous in vivo studies and GPX4, NFE2L2, SCN9A, EPSTI1 and IGFBP3 selected from in vitro studies. Moreover, metabolic analyses were performed on the media obtained from the co-culture. Results revealed that presence of early embryos or their CM altered the BOEC expression of NFE2L2, GPX4, SMAD6, IGFBP3, ROCK2 and SCN9A. However, the response of BOEC to two-cell embryos or their CM was different from that observed to eight-cell embryos or their CM. Analysis of energy substrates and amino acids revealed that BOEC metabolism was not affected by the presence of early embryos or by their CM. Interestingly, embryo metabolism before embryo genome activation (EGA) seems to be independent of exogenous sources of energy. In conclusion, this study confirms that early embryos affect BOEC transcriptome and BOEC response was embryo stage specific. Moreover, embryo affects BOEC via a direct contact or via its secretions. However transcriptomic response of BOEC to the embryo did not manifest as an observable metabolic response.

DNA methylation changes during preimplantation development reveal inter-species differences and reprogramming events at imprinted genes

Preimplantation embryos experience profound resetting of epigenetic information inherited from the gametes. Genome-wide analysis at single-base resolution has shown similarities but also species differences between human and mouse preimplantation embryos in DNA methylation patterns and reprogramming. Here, we have extended such analysis to two key livestock species, the pig and the cow. We generated genome-wide DNA methylation and whole-transcriptome datasets from gametes to blastocysts in both species. In oocytes from both species, a distinctive bimodal methylation landscape is present, with hypermethylated domains prevalent over hypomethylated domains, similar to human, while in the mouse the proportions are reversed.

An oocyte-like pattern of methylation persists in the cleavage stages, albeit with some reduction in methylation level, persisting to blastocysts in cow, while pig blastocysts have a highly hypomethylated landscape. In the pig, there was evidence of transient de novo methylation at the 8–16 cell stages of domains unmethylated in oocytes, revealing a complex dynamic of methylation reprogramming. The methylation datasets were used to identify germline differentially methylated regions (gDMRs) of known imprinted genes and for the basis of detection of novel imprinted loci. Strikingly in the pig, we detected a consistent reduction in gDMR methylation at the 8–16 cell stages, followed by recovery to the blastocyst stage, suggesting an active period of imprint stabilization in preimplantation embryos. Transcriptome analysis revealed absence of expression in oocytes of both species of ZFP57, a key factor in the mouse for gDMR methylation maintenance, but presence of the alternative imprint regulator ZNF445. In conclusion, our study reveals species differences in DNA methylation reprogramming and suggests that porcine or bovine models may be closer to human in key aspects than in the mouse model.

OR17-07 Retinol Binding Protein 4 Predicts Functional Vascular Disease in Early Postmenopausal Women

Introduction: The impact of gender on the development of cardiovascular disease has long been recognized. The potential effect of sex-specific cardiovascular risk factors on molecular mediators of oxidative stress has received limited attention and the results remain conflicting.

Hypothesis: To assess the link between retinol binding protein 4 (RBP4) and menopause-specific cardiovascular risk factors, on indices of early subclinical atherosclerosis, in a sample of apparently healthy young, postmenopausal women.

Methods: This cross-sectional study included a total of 123 healthy postmenopausal women, recruited from a University Menopause Clinic. Participating women were, not on hormone therapy, antihypertensive or hypolipidemic treatment and had a menopausal age of up to 10 years. Fasting venous blood samples were obtained for hormonal and biochemical assessment, including levels of RBP4. Sonographical studies were performed on the same day and included carotid-femoral pulse wave velocity (PWV) and calculation of the carotid artery stiffness index (SI).

Major results: Univariate analysis showed that RBP4 values correlated positively with age, total cholesterol, triglycerides, LDL-cholesterol, testosterone-to-estrogen ratio; negatively with circulating estrogen and almost significantly with homocysteine levels. Levels of homocysteine were inversely associated with RBP4 (homocysteine: RBP4 &lt;10.5ng/ml vs ≥10.5ng/ml: 11.2±2.81μmol/L vs 12.52±3.44μmol/L, p-value=0.049 ANCOVA, adjusted for age, BMI, HOMA-IR). Multivariate analysis showed that PWV values were predicted by RBP4 (b-coefficient=0.435, p-value=0.006), age, pulse pressure, homocysteine. S.I. beta was predicted independently by RBP4 levels (b-coefficient=0.324, p-value=0.039). Both models were adjusted for menopausal age, LDL-cholesterol, FEI, smoking, HOMA-IR.

Conclusion: RBP4 levels are linked with measures of local carotid and aortic arterial stiffness, in this sample of healthy postmenopausal women. This association seems to be mediated by higher levels of homocysteine, which may interfere with retinoic acid synthesis. Larger studies are required to further elucidate the significance of our findings.

References

1. Majerczyk M, Olszanecka-Glinianowicz M, Puzianowska-Kuznicka M, Chudek J: Retinol-binding protein 4 (RBP4) as the causative factor and marker of vascular injury related to insulin resistance. Postepy Hig Med Dosw 2016;70:1267-1275.

2. Smolders RG, van der Mooren MJ, Sipkema P, Kenemans P: Estrogens, homocysteine, vasodilatation and menopause: basic mechanisms, interactions and clinical implications. Gynecol Endocrinol 2003;17:339-354.

3. Limpach A, Dalton M, Miles R, Gadson P: Homocysteine inhibits retinoic acid synthesis: a mechanism for homocysteine-induced congenital defects. Exp Cell Res 2000;260:166-174.

The effect of rapamycin on bovine oocyte maturation success and metaphase telomere length maintenance

Maternal aging-associated reduction of oocyte viability is a common feature in mammals, but more research is needed to counteract this process. In women, the first aging phenotype appears with a decline in reproductive function, and the follicle number gradually decreases from menarche to menopause. Cows can be used as a model of early human embryonic development and reproductive aging because both species share a very high degree of similarity during follicle selection, cleavage, and blastocyst formation. Recently, it has been proposed that the main driver of aging is the mammalian target of rapamycin (mTOR) signaling rather than reactive oxygen species. Based on these observations, the study aimed to investigate for the first time the possible role of rapamycin on oocyte maturation, embryonic development, and telomere length in the bovine species, as a target for future strategies for female infertility caused by advanced maternal age. The 1nm rapamycin in vitro treatment showed the best results for maturation rates (95.21±4.18%) of oocytes and was considered for further experiments. In conclusion, rapamycin influenced maturation rates of oocytes in a concentration-dependent manner. Our results also suggest a possible link between mTOR, telomere maintenance, and bovine blastocyst formation.

Anti-Müllerian Hormone Concentrations Are Inversely Associated With Subclinical Atherosclerosis in Premenopausal Women

Anti-Müllerian hormone (AMH), which is secreted by granulosa cells of late preantral and small antral follicles, is a marker of ovarian reserve. The association of ovarian reserve with subclinical atherosclerosis in women of reproductive age is currently unknown. We primary investigated whether AMH levels are associated with markers of subclinical atherosclerosis in healthy, normally menstruating women. In this cross-sectional study, vascular structure and function were assessed by measurement of carotid and femoral intima–media thickness (IMT), flow-mediated dilation, carotid–femoral pulse wave velocity and augmentation index. Lipid profile and serum AMH concentrations were also measured. Seventy premenopausal women, aged 32.7 ± 6.5 years, were included. Mean AMH levels were lower in smokers than in non-smokers and negatively associated with total cholesterol (TC) levels. An inverse association between mean AMH concentrations and femoral and carotid IMT in all segments was observed. No correlation with other markers of subclinical atherosclerosis or established cardiovascular (CV) risk factors was found. After multivariable adjustment, the association between AMH concentrations and combined carotid IMT or carotid bulb IMT remained significant. In conclusion, in healthy, normally ovulating women, AMH concentrations are negatively associated with subclinical atherosclerosis indices and TC levels, independently of established CV risk factors.

Spatial and Pregnancy-Related Changes in the Protein, Amino Acid, and Carbohydrate Composition of Bovine Oviduct Fluid

Knowledge of how the biochemical composition of the bovine oviduct is altered due to the oviduct anatomy or the presence of an embryo is lacking. Thus, the aim of this study was to assess the effect of (І) oviduct anatomy and (ІІ) embryo presence on oviductal fluid (OF) protein, amino acid, and carbohydrate composition. Cross-bred beef heifers (n = 19) were synchronized and those in standing estrus were randomly allocated to a cyclic (non-bred) or pregnant (artificially inseminated) group. All heifers were slaughtered on Day 3 after estrus. The oviducts ipsilateral to the corpus luteum from each animal were isolated, straightened and cut, separating ampulla and isthmus. Each portion was flushed with 500 µl of PBS enabling recovery of the oocyte/embryo. Recovered unfertilized oocytes (cyclic group) and embryos (8-cell embryos; pregnant group) were located in the isthmus of the oviduct. Samples of flushing medium from the isthmus and ampulla were used for proteomic (n = 2 per group), amino acid (n = 5), and carbohydrate (n = 5) analysis. For proteomic analysis, total protein from cyclic and pregnant samples were labelled with different cyanine fluorescent probes and separated according to the isoelectric point using immobilized pH gradient strips (pH 3-10, 17 cm, Protean® IEF cell system, Bio Rad). Second dimension was performed in a polyacrylamide gel (12%) in the presence of SDS using a Protean II XL system (Bio Rad). Images were obtained with a Typhoon 9410 scanner and analyzed with Progenesis SameSpots software v 4.0. Amino acid content in the OF was determined by high performance liquid chromatography (HPLC). Glucose, lactate, and pyruvate were quantified using microfluorometric enzyme-linked assays. For the proteomic assessment, the results of the image analysis were compared by ANOVA. For both amino acid and carbohydrate analyses, statistical analysis was carried out by 2-way ANOVA with the Holm-Sidak nonparametric post hoc analysis. On Day 3 post-estrus, OF composition varied based on (І) anatomical region, where isthmic metabolites were present in lower (i.e., lactate, glycine, and alanine) or higher (i.e., arginine) concentrations compared to the ampulla; and (ІІ) embryo presence, which was correlated with greater, arginine, phosphoglycerate kinase 1, serum albumin, α-1-antiproteinase and IGL@ protein concentrations. In conclusion, data indicate that the composition of bovine OF is anatomically dynamic and influenced by the presence of an early embryo.

Ultra-rapid cooling of ibex sperm by spheres method does not induce a vitreous extracellular state and increases the membrane damages

Sperm cryopreservation by ultra-rapid cooling based on dropping small volumes of sperm suspension directly into liquid nitrogen, has been successful in some wild ruminant species, including the Iberian ibex (Capra pyrenaica). In ultra-rapid cooling, the contents of these droplets are expected to enter a stable, glass-like state, but to the best of our knowledge no information exists regarding the presence or absence of ice formation in the extracellular milieu when using this technique. Different modifications to the extracellular milieu likely inflict different types of damage on the plasmalemma, the acrosome and mitochondrial membranes. The aims of the present work were: 1) to examine the physical state of the extracellular milieu after cryopreservation at slow and ultra-rapid cooling rates—and thus determine whether ultra-rapid cooling vitrifies the extracellular milieu; and 2) to compare, using conventional sperm analysis techniques and scanning and transmission electron microscopy, the damage to sperm caused by these two methods. Sperm samples were obtained by the transrectal ultrasound-guided massage method (TUMASG) from anesthetized Iberian ibexes, and cryopreserved using slow and ultra-rapid cooling techniques. Sperm motility (22.95 ± 3.22% vs 4.42 ± 0.86%), viability (25.64 ± 3.71% vs 12.8 ± 2.50%), acrosome integrity (41.45± 3.73% vs 27.00 ± 1.84%) and mitochondrial membrane integrity (16.52 ± 3.75% vs 4.00 ± 0.65%) were better after slow cooling (P<0.001) than after ultra-rapid technique. Cryo-scanning electron microscopy (Cryo-SEM) suggested that the vitrified state was not achieved by ultra-rapid cooling, and that the ice crystals formed were smaller and had more stretchmarks (P<0.001) than after slow cooling. Scanning electron microscopy revealed no differences in the types of damage caused by the examined techniques, although transmission electron microscopy showed the damage to the plasmalemma and mitochondrial membrane to be worse after ultra-rapid cooling. In conclusion ultra-rapid cooling provoked more membrane damage than slow cooling, perhaps due to the extracellular ice crystals formed.

76 Extracellular vesicles from oviduct and uterus in sequential culture improve the quality of bovine embryos produced invitro

Extracellular vesicles (EVs) are released by cells and transport cargo that affect functions of other cells. Oviductal fluid (OF) and uterine fluid (UF) have been shown to improve quality of embryos during invitro culture (Hamdi et al. 2017 Reprod. Fertil. Dev. 30, 935-945) which may be due to their content of EV (Lopera-Vásquez et al. 2017 Reproduction 153, 461-470). Thus, the aim of this study was to evaluate the effect of EVs from OF and UF on a sequential invitro culture system on the development and quality of bovine embryos. Zygotes were cultured in synthetic oviduct fluid (SOF) supplemented with 3mgmL−1 bovine serum albumin (BSA; n=1228) or 5% EV-depleted fetal calf serum (dFCS, n=1261) in the presence (BSAEV, n=1265 and dFCSEV, n=1253) or absence of 3×105 EVmL−1 from OF (Day 1 to Day 4) and UF (Day 4 to Day 9), mimicking invivo conditions. The EVs pooled from 5 oviducts (early luteal phase) and 5 uterine horns (middle luteal phase) from slaughtered heifers were isolated by a Size Exclusion Chromatography kit (Hansa BioMed). The EV size and concentration were assessed by the nanotracking analysis system and morphology by transmission electron microscopy. Embryo development was recorded on Days 7/9. Day 7/8 blastocysts were assessed for quality by staining with (a) Hoechst 33342 (10 µgmL−1, 30min) for total cell number, (b) Bodipy 493/503 (20 µgmL−1, 1h) for lipid content (lipid droplet area in µm2), and (c) for survival rate after vitrification/warming. Data were analysed by one-way ANOVA and Tukey test. The EV concentration was 2.97 and 7.98×1010 particlesmL−1, and mode size 137.2 and 151.2nm for OF and UF, respectively. Transmission electron microscopy confirmed EV presence and size, showing typical cup-shaped morphology. Blastocyst yield was lower (P&lt;0.05) on Day 7 in the BSA groups (BSA: 15.7±1.9 and BSAEV: 15.2.4%) compared with serum groups (dFCS: 28.1±2.6 and dFCSEV: 30.1±2.9%) irrespective of EV supplementation; however, these differences were compensated at Days 8 and 9 (range: 30.0±3.2-40.8±3.9%). The EVs increased (P&lt;0.05) blastocyst total cell number in dFCSEV (152.6±2.9) and BSAEV (140.5±1.5) compared with dFCS (117.9±2.0) and BSA groups (122.4±1.1). However, lipid content was decreased (P&lt;0.05) in the presence of EVs only in dFCSEV (0.231±0.05µm2) compared with BSA (0.393±0.03µm2) and BSAEV (0.379±0.03µm2) groups. The dFCS did not differ from any group (0.371±0.05µm2; P&gt;0.05). Blastocyst survival after vitrification/warming was high in all groups up to 72h (range: 80.0±3.8-100%; P&gt;0.05). In conclusion, mimicking physiological conditions using EV from OF and UF during invitro culture does not affect development but improves embryo quality by increasing blastocyst total cell numbers and decreasing lipid contents. These results provide evidence of the association of the reproductive tract environment and developing embryo, confirming embryo-maternal communication. Funding was provided by MINECO-Spain AGL2015-70140-R; Y. N. Cajas, SENESCYT-Ecuador; C. L. V. Leal, FAPESP-Brazil 2017/20339-3.

75 Expression of lipid metabolism-related genes in bovine embryos cultured invitro with diacylglycerol acyltransferase-1 inhibitor

Intracellular lipids accumulated in embryos produced invitro have been linked to reductions in both quality and post-cryopreservation viability. Diacylglycerol O-acyltransferase 1 (DGAT1) is an enzyme that catalyzes the final step in triglyceride synthesis, which is a major component of the lipid droplets in embryos. Thus, the aim of this study was to evaluate the development and quality, in regard to changes in the expression of candidate genes of lipid metabolism, of bovine blastocysts cultured invitro with DGAT1 inhibitor (A922500 Sigma-Aldrich). Zygotes were cultured in synthetic oviduct fluid supplemented with 5% FCS (TC) or in TC supplemented with 10 or 50 µM DGAT1 inhibitor (T10 and T50, respectively) or TC with 0.1% dimethyl sulfoxide (TDMSO: vehicle for DGAT1 dilution) from 54h post-insemination (hpi; major embryonic genome activation, EGA) until Day 8. Cleavage rate (48 hpi) and blastocyst yield (Day 7-8) were evaluated. Day 7 blastocysts were snap-frozen in LN2 for gene expression analysis. The mRNA abundance of candidate genes related to lipid metabolism (DGAT1, PLIN2, GLUT5, GLUT1, GPX1, PPAR1b, and G6PD) was measured by quantitative PCR. The H2AFZ and ACTB genes were used as housekeeping genes. Statistical analysis was assessed by one-way analysis of variance. No differences were found in cleavage rate, whereas blastocyst yield at Day 8 was higher (P&lt;0.05) for T50 (30.5±0.5%) and TC (29.7±0.5%) compared with T10 (25.6±0.5%) and TDMSO (27.1±0.8%). The expression of genes regulating lipid droplet formation (DGAT1 and PLIN2) was down-regulated in embryos of T10 and T50 groups compared with controls (P&lt;0.05) only for DGAT1, whereas no differences were observed for PLIN2. The expression of GLUT5, a fructose metabolism transporter gene, was only increased in embryos in the T10 group, whereas the relative abundance of GLUT1 (involved in glucose metabolism) was up-regulated in T10 and T50 groups compared with controls (P&lt;0.05). The GPX1 gene was decreased significantly in embryos from both DGAT1-inhibitor groups compared with the controls. The expression profile of PPAR1b and G6PD, lipid metabolism-regulating genes, were not different among embryo groups. In conclusion, supplementation of embryo culture with DGAT1 inhibitor improves development and blastocyst quality in terms of the expression of lipid metabolism-regulating genes, supporting a relationship between lipid metabolism and embryo feature. Funding was provided by MINECO-Spain AGL2015-70140-R &amp; RTI2018-093548-B-I00; J. Giraldo-Giraldo COLCIENCIAS 727/2015-Colombia; Y. N. Cajas, SENESCYT-Ecuador; C. L. V. Leal, FAPESP-Brasil 2017/20339-3.

77 Nobiletin supplementation affects gene expression profiles of the Akt pathway in bovine embryos invitro

Embryonic genome activation (EGA) is a critical event in early embryonic development and occurs in 8-16-cell stage embryos in bovine. Invitro embryo production increases reactive oxygen species (ROS), leading to low yield and cell death. Nobiletin is an antioxidant that inhibits ROS production and affects cell cycle regulation. The aim of this study was to evaluate the effect of nobiletin supplementation in two key periods of early embryo development on blastocyst yield and expression of candidate genes of the Akt pathway. Invitro-produced zygotes were cultured in synthetic oviductal fluid supplemented with 5% FCS (control; C); C with 5 or 10 µM nobiletin (MedChemExpress; N5, N10) or C with 0.03% dimethyl sulfoxide (CD vehicle for nobiletin dilution) during the minor (2-8-cell stage; MNEGA) or major (8-16-cell stage; MJEGA) phase of EGA, considered as two separate experiments. For all groups, the speed of development was considered, and normally developing embryos that reach ≥8 cells at 54h post-insemination and ≥16 cells at 96h post-insemination were selected and cultured in control medium until Day 8, respectively. Embryos at ≥8-cell stage (N5/N10 MNEGA), 16-cell stage (N5/N10MJEGA), and Day 7 blastocysts of both periods were snap-frozen in LN2 for gene expression analysis. Cleavage rate and blastocyst yield (Day 7-8) were evaluated. The mRNA abundance of candidate genes related to the Akt pathway (CDK2, PGC1A, PPARG, RPS6KB1) and oxidative stress (GPX1) was measured by quantitative PCR. The H2AFZ and ACTB genes were used as housekeeping genes. Statistical analysis was assessed by one-way ANOVA. Nobiletin supplementation during MNEGA showed no differences in cleavage rate, whereas the blastocyst yield at Day 8 was higher (P&lt;0.001) for N5 (42.9±1.4%) and N10 (45.3±2.1%) compared with C (32.9±1.1%) and CD (32.6±1.4%) groups. When nobiletin was supplemented during MJEGA, no differences were found in cleavage rate; however, Day 8 blastocyst yield was higher (P&lt;0.001) for N10 (61.8±0.7%) compared with C (45.2±1.7%), CD (43.6±1.4%), and N5 (52.1±2.1%) groups, whereas N5 was higher (P&lt;0.05) compared with both control groups. The mRNA abundance of CDK2 significantly increases in 8-cell stage embryos from N5 and N10 groups during MNEGA, whereas 16-cell stage embryos from N10 group during MJEGA showed a significant increase compared with both controls (P&lt;0.05). The expression of PGC1A was significantly higher in blastocysts from N5, N10 during MNEGA, and N10 during MJEGA groups compared with both controls (P&lt;0.05). No differences were observed for PPARG and RPS6KB1 in any group from both phases. GPX1, an oxidative indicator gene, was up-regulated in all nobiletin-supplemented groups from both phases compared with controls (P&lt;0.05). In conclusion, supplementation of embryo culture during MNEGA or MJEGA with nobiletin improves embryo development and induces changes in the transcriptional genes related to cell cycle regulation and oxidative stress. This suggests that nobiletin acts through the Akt pathway during the first stages of embryonic development. Funding was provided by MINECO-Spain AGL2015-70140-R&amp;RTI2018-093548-B-I00; Y. N. Cajas, SENESCYT-Ecuador; C. L. V. Leal, FAPESP-Brasil 2017/20339-3.

Predictors of incident hypertension in healthy non-diabetic postmenopausal women with normal renal function

Introduction: We aimed to investigate the incidence of hypertension and to identify potential risk factors in healthy, non-diabetic recently postmenopausal Greek women with normal renal function.Patients and methods: This retrospective cohort study evaluated 141 recently postmenopausal women at baseline and annually thereafter (follow-up time: 1 to 8 years). Blood samples were obtained, and ultrasound evaluations were performed at baseline. A detailed medical history, anthropometric parameters, blood pressure and cardiovascular risk factors were recorded for every woman at each visit. Incident hypertension was defined as the first occurrence of office systolic or diastolic blood pressure, measured at 2 different visits within 2 months or history of initiation of antihypertensive medication.Results: Incident hypertension was diagnosed in 30 out of 141 women (21.3%). The median time to incident hypertension was 3.5 years. Adiposity, elevated cholesterol and triglyceride levels, insulin resistance and parity were positively associated with incident hypertension. In multivariate analysis, however, obesity and insulin resistance were the only statistically significant variables associated with more than 3-fold and 2-fold respectively increased risk of incident hypertension (HOMA-IR, O.R = 1.988, p-value =.043; obesity, O.R = 3.746, p-value =.019).Conclusion: A significant proportion of women entering the menopause present incident hypertension and this is mostly associated with obesity and insulin resistance.

An approach to study the local embryo effect on gene expression in the bovine oviduct epithelium in vivo

This study aimed to examine the local embryo effect on the transcriptomic response of the epithelial cells of the oviduct in vivo. Fifteen heifers were synchronized and artificially inseminated to a standing heat. All heifers were slaughtered on Day 2.5 after oestrus. The oviducts from 13 animals were isolated, trimmed free of tissue and divided between ampulla/isthmus. The ipsilateral isthmus was divided into smaller sections (2 cm). Each section was sequentially flushed until the embryo was located (4/13) and then opened and scraped longitudinally to obtain the epithelial cells. Cells were snap-frozen in LN₂ for gene expression analysis. All recovered embryos were found at the beginning of the isthmus. The 2 cm sections selected for the transcriptomic analysis were as follows: embryo section (in which the embryo was found); proximal section (through which the embryo had passed); distal section (on the uterine side of the embryo); and contralateral section (section from the contralateral isthmus). The expression pattern of eight genes (STK32A, KERA, QRFPR, MCTP1, PRELP, VAT1L, SOCS3 and CCL20) differentially expressed between the isthmus of pregnant (multiple embryo model) and cyclic heifers were assessed by RT-qPCR. One-way ANOVA and t test was used for statistical analysis. Comparisons between ipsilateral and contralateral oviduct or along the ipsilateral oviduct resulted in no differences for all genes. Despite the failure to detect a site-specific response of a single embryo on the abundance of distinct transcripts in the bovine oviduct in vivo on Day 2.5, the current methodology with proposed modifications would be useful for future studies to examine the local embryo effect.

Bovine oviductal and uterine fluid support in vitro embryo development

In order to mimic the maternal oviductal environment, we evaluated the effect of oviductal fluid (OF) and/or uterine fluid (UF) supplementation on in vitro embryo development and quality. In vitro-produced zygotes were cultured with 1.25% OF from Day 1 to Day 4 after insemination (OF group), 1.25% OF from Day 1 to Day 4 followed by 1.25% UF from Day 4 to Day 9 (OF+UF group) or 1.25% UF only from Day 4 to Day 9 (UF group). Control groups were cultured in the presence of synthetic oviduct fluid (SOF) supplemented with 3mgmL-1 bovine serum albumin (BSA) or 5% fetal calf serum (FCS). Supplementation of the culture medium with OF and/or UF (both at 1.25%) supported embryo development (Day 9 blastocyst rate 28.2-30.6%). At 72h after vitrification-warming, the survival of blastocysts from the OF and OF+UF groups was similar to that of blastocysts in the SOF+BSA group (61.0±5.7% and 62.8±6.4% vs 64.8±6.4% respectively), but significantly higher than that of blastocysts from the SOF+FCS group (31.6±4.9%; P<0.001). Blastocysts from the OF group exhibited upregulation of epigenetic genes (i.e. DNA methyltransferase 3α (DNMT3A) and insulin-like growth factor 2 receptor (IGF2R)), compared with expression in the SOF+FCS group (P<0.05). Whereas those from OF+UF and UF groups exhibited downregulation of oxidative stress genes compared to SOF+BSA and OF groups for glutathione peroxidase (GPX1) and to SOF+FCS, SOF+BSA and OF groups for chloride intracellular channel 1 (CLIC1) (P<0.05). In addition, accumulation of reactive oxygen species was lower in blastocysts from the OF, OF+UF and UF groups. In conclusion, the use of low concentrations of OF and UF in in vitro serum-free culture supports embryo development, with OF providing a better control of embryo methylation, whereas UF may have antioxidant activity.

Influence of sperm filtration and the addition of glycerol to UHT skimmed milk- and TEST-based extenders on the quality and fertilizing capacity of chilled ram sperm

The poor fertility of ram semen stored chilled for long periods has encouraged the development of protocols designed to improve the kinetic vigour and cervical barrier-crossing capacity of sperm. The present work evaluated the effect of sperm selection with Sephadex filtration and the supplementation of 2% glycerol (GLY) to extenders based on ultra-heat-treated skimmed milk (UHT) or Tris-Tes-Glucose (TEST) on ram sperm kinetic parameters, plasma membrane integrity, acrosome integrity, mitochondrial function and fertilizing ability, over long chilling times. The results showed that for non-filtered semen, values for progressive sperm motility (%PSM), straight line velocity (VSL, μm/s) and the percentage of sperm with an intact plasma membrane/intact acrosome/a high mitochondrial function index (%IPIAHM) at all times up to 96 h of chilling were higher when the UHT extender (P < 0.01) was used compared to TEST extender irrespective of the presence of GLY. When semen was previously filtered with Sephadex, the addition of GLY to the UHT extender improved total motility (%TM), the %PSM and the VSL at 96 h compared to all other treatments (P < 0.01). The best results of all were obtained with non-filtered semen and UHT either with or without GLY. Heterologous IVF using zona-intact bovine oocytes was used to assess the fertilizing capacity of non-filtered fresh (FS0), chilled-for-24 h (CS24) or chilled-for-48 h (CS48) ram semen diluted in UHT extender (GLY-free). Heterologous IVF showed that ram sperm, either FS0, CS24 or CS48, were equally capable of penetrating zona pellucida intact bovine oocytes, leading to pronuclear formation and hybrid embryo cleavage (46.3 ± 3.2; 48.8 ± 3.2; and 43.3 ± 3.5, respectively). No differences were seen with respect to fresh sperm in terms of sperm binding, penetration, polyspermy, pronucleus formation or cleavage rates (P > 0.05). In conclusion, neither Sephadex filtration nor addition of glycerol provided extra benefits to ram sperm chilled up to 96 h. Chilled, non-filtered sperm extended with UHT without GLY showed better sperm functionality than did similar sperm extended with TEST extenders. Indeed, sperm diluted in UHT extender, maintained fertilizing ability up to 48 h.

Ascorbic acid-cyclodextrin complex alters the expression of genes associated with lipid metabolism in bovine in vitro produced embryos

Ascorbic acid (AC) used as antioxidant in embryo culture is very sensitive and degrades unavoidably in aqueous solution. Methyl-β-cyclodextrin (CD) improved the stability of AC in solution to elevated temperature, light, humidity and oxidation. The aim of this study was to evaluate the effect of the complex AC-CD during in vitro maturation (IVM) or in vitro culture (IVC) on oocyte developmental competence and subsequent embryo development and quality. AC-CD (100 µM) was added to IVM media, and maturation level and embryo development were examined. Matured oocytes, their cumulus cells and produced blastocysts were snap-frozen for gene expression analysis by RT-qPCR. Besides, in vitro-produced zygotes were cultured with 100 µM of AC-CD and blastocysts were as well snap-frozen for gene expression analysis. A group without AC-CD (control^- ) and other with CD (control⁺ ) were included. No differences were found on maturation, cleavage or blastocyst rates. However, in matured oocytes, AC-CD downregulated BAX, GPX1 and BMP15. In cumulus cells, AC-CD downregulated BAX/BCL2 and GSTA4 while upregulated BCL2 and CYP51A1. The expression of SL2A1, FADS1, PNPLA and MTORC1 was downregulated in blastocysts derived from oocytes matured with AC-CD, while in blastocysts derived from zygote cultured with AC-CD, CYP51A1 and IGF2R were downregulated and PNPLA2 was upregulated. In conclusion, AC-CD in both IVM and IVC media may reduce accumulated fat by increasing lipolysis and suppressing lipogenesis in blastocysts derived from both oocytes and zygotes cultured with AC-CD, suggesting that CD improves the quality of embryos and bioavailability of AC during IVM and IVC.

175 Nobiletin enhances the quality of in vitro-matured bovine oocytes and blastocysts by altering the transcription of key developmental genes

One of the problems associated with in vitro production of embryos in bovine is the increase in reactive oxygen species (ROS), which leads to cell alterations and death. Nobiletin is a polymethoxyflavone isolated from citrus fruits with various beneficial effects on cell cycle regulation and inhibition of ROS production. In a preliminary study, we demonstrated that supplementation of 25 or 50 µM nobiletin to the in vitro maturation (IVM) medium reduces oxidative stress and improves oocyte nuclear and cytoplasmic maturation and embryo development. Thus, in this study, we aimed to evaluate the antioxidant activity of nobiletin during IVM on bovine matured oocytes, their cumulus cells (CC), and blastocysts by quantitative changes of gene expression. Immature cumulus oocytes complexes (COC) were aspirated from ovaries of slaughtered heifers. Selected COC underwent IVM in TCM-199+10% FCS and 10ng mL−1 epidermal growth factor (EGF; Control) supplemented with 25 µM (Nob25) or 50 µM (Nob50) nobiletin (MedChemExpress, Monmouth Junction, NJ, USA) or 0.001% dimethyl sulfoxide (DMSO control), a vehicle for nobiletin dilution, in 5% CO2 in air at 38.5°C. After 24h, 50 matured oocytes/group and their CC were snap-frozen in LN2 for gene expression analysis. The remaining oocytes were fertilized (Day 0) and cultured in vitro. Blastocysts (Day 7; n=50/group) were snap-frozen in LN2 for gene expression analysis (5 replicates). The mRNA abundance of candidate genes related with oxidative stress (SOD2, CYP51); apoptosis (BAX); quality (BMP15, BMP7, CLIC1, MAPK1, ABCB1); and cell junction (GJA1) was measured by quantitative PCR; H2AFZ and 18S rRNA were used as housekeeping genes. Statistical significance was assessed by one-way ANOVA. Supplementation of IVM medium with Nob25 or Nob50 produced changes in the expression levels of genes related to oxidative stress and apoptosis during IVM compared with controls. SOD2 and CYP51 were down-regulated in oocytes and CC (P&lt;0.05) but not in blastocysts, whereas BAX was down-regulated only in CC (P&lt;0.05). Nobiletin supplementation in IVM increased the expression of MAPK1 in oocytes and blastocysts (P&lt;0.05); however, no differences were observed in CC. BMP15 for oocytes and their CC and GJA1 for CC were up-regulated in Nob25 and Nob50 groups compared with controls (P&lt;0.05). The relative abundance of CLIC1 decreased in blastocysts from both nobiletin groups compared with controls (P&lt;0.05). No significant differences in the expression in ABCB1 and BMP7 were detected. In conclusion, our results suggest that supplementation of 25 or 50 µM nobiletin to the IVM medium reduces oxidative stress in oocytes and CC, decreases CC apoptosis, and provokes positive changes in the expression of genes related to oocyte and embryo quality. This research was supported by Spanish MINECO (AGL2015-70140-R and AGL2015-66145-R). Y. N. Cajas was supported by a grant from SENESCYT-Ecuador.

137 Assessment of fertilizing ability of Merino ram semen cold stored up to 48h by heterologous IVF of bovine oocytes

The use of cold-stored ram semen has been applied in sheep AI programs, because it preserves its fertilizing ability similar to fresh. Besides, the heterologous IVF has been successfully employed to assess semen fertilizing ability in several species. Hence, we aimed to evaluate the fertilizing ability of ram semen cold stored up to 48h at 5°C by assessing heterologous IVF using bovine oocytes. Fifteen pools of 3 normospermic Merino ram (2-7 years) ejaculates were collected using artificial vagina, diluted to 200×106 spermatozoa mL−1 with ultra-heat-treatment-based extender (skim milk-6% egg yolk) and cold stored up to 48h. In vitro matured zona-intact bovine oocytes were subjected to heterologous IVF using fresh semen (FS, n=707), semen cold stored to 24h (CS24, n=832) or semen cold stored to 48h (CS48, n=611). In parallel, homologous IVF (control, n=1356) and parthenogenesis (parth control non-fertilized oocytes, n=334) were performed. Ram non-selected and selected (BoviPure, Nidacon International, Mölndal, Sweden) semen parameters were evaluated by computer-assisted semen analysis. Sperm-oocyte interaction was assessed at 2.5h post-insemination (hpi) by evaluating the number of bound spermatozoa, whereas penetration and polyspermy were evaluated after 12 hpi. Presumptive zygotes were fixed and stained with Hoechst 33342 at 18, 20, 22, 24 and 26 hpi to assess pronuclear formation using phase contrast and confocal microscopy. Cleavage rate was evaluated in all groups at 48 hpi. Data obtained from 5 replicates were analysed using one-way ANOVA. Data was expressed as mean±standard error of the mean. In terms of sperm storage time, non-selected semen showed a significant decrease (P&lt;0.05) for CS24 and CS48 compared with FS on progressive motility [SPM (%): 52.30±4.1 and 36.9±5.5v. 71.3±1.6] and straight-line velocity (mm s−1: 132.2±6.1 and 109.7±6.3v. 176.7±4.3), respectively. However, selected semen showed a decrease (P&lt;0.05) only for CS48 when compared with CS24 or FS on SPM (35.6±3.9v. 56.1±6.91 and 59.3±2.6) and straight-line velocity (83.5±4.4v. 105.3±6.5 and 110±2.0), respectively. No differences were observed between heterologous IVF groups in all parameters evaluated. Homologous IVF showed a higher percentage of penetration only when compared with heterologous FS group (44.4±6.8v.12.5±4.5%; P&lt;0.01). The polyspermy was higher in heterologous CS24 group when compared with homologous IVF (11.4±3.4v. 3.8±2.2; P&lt;0.05). The homologous IVF group, as expected, showed the higher percentage of pronuclear formation at 18 hpi compared with heterologous IVF with FS (67.3±5.8v. 35.2±5.6%), CS24 (72.1±4.5 v. 37.2±5.7%) and CS48 (63.0±6.0 v. 27.0±5.6%), respectively (P&lt;0.001). Likewise, cleavage rate was higher in homologous group compared with heterologous IVF and parthenogenetic groups for FS (78.3±2.6.8v. 46.3±3.2 and 7.0±2.3%), CS24 (78.4±2.6 v. 48.3±3.2 and 4.9±2.0%), and CS48 (78.4±3.3 v. 43.3±3.5 and 4.3±1.2%), respectively (P&lt;0.001). In conclusion, Merino ram semen cold stored up to 48h maintains its fertilization ability to the same extend as fresh and can be used for sheep crossbreeding programs.