Coculture with porcine luteal cells during in vitro porcine oocyte maturation affects lipid content, cortical reaction and zona pellucida ultrastructure

CONTEXT

In pigs, in vitro fertilisation (IVF) is associated with high polyspermy rates, and for this reason, in vitro embryo production (IVP) is still an inefficient biotechnology. Coculture with somatic cells is an alternative to improve suboptimal in vitro maturation (IVM) conditions.

AIM

This study was conducted to test a coculture system of porcine luteal cells (PLC) and cumulus-oocyte complexes (COC) to improve oocyte metabolism.

METHODS

COC were matured in vitro with PLC. Oocyte lipid content, mitochondrial activity, zona pellucida (ZP) digestibility and pore size, cortical reaction and in vitro embryo development were assessed.

KEY RESULTS

Coculture reduced cytoplasmic lipid content in the oocyte cytoplasm without increasing mitochondrial activity. Although ZP digestibility and ZP pore number were not different between culture systems, ZP pores were smaller in the coculture. Coculture impacted the distribution of cortical granules as they were found immediately under the oolemma, and more of them had released their content in the ZP. Coculture with porcine luteal cells during IVM increased monospermic penetration and embryo development after IVF.

CONCLUSIONS

The coculture of COC with PLC affects the metabolism of the oocyte and benefits monospermic penetration and embryo development.

IMPLICATIONS

The coculture system with PLC could be an alternative for the conventional maturation medium in pigs.

Past, present and future of ICSI in livestock species

During the past 2 decades, intracytoplasmic sperm injection (ICSI) has become a routine technique for clinical applications in humans. The widespread use among domestic species, however, has been limited to horses. In horses, ICSI is used to reproduce elite individuals and, as well as in humans, to mitigate or even circumvent reproductive barriers. Failures in superovulation and conventional in vitro fertilization (IVF) have been the main reason for the use of this technology in horses. In pigs, ICSI has been successfully used to produce transgenic animals. A series of factors have resulted in implementation of ICSI in pigs: need to use zygotes for numerous technologies, complexity of collecting zygotes surgically, and problems of polyspermy when there is utilization of IVF procedures. Nevertheless, there have been very few additional reports confirming positive results with the use of ICSI in pigs. The ICSI procedure could be important for use in cattle of high genetic value by maximizing semen utilization, as well as for utilization of spermatozoa from prepubertal bulls, by providing the opportunity to shorten the generation interval. When attempting to utilize ICSI in ruminants, there are some biological limitations that need to be overcome if this procedure is going to be efficacious for making genetic improvements in livestock in the future. In this review article, there is an overview and projection of the methodologies and applications that are envisioned for ICSI utilization in these species in the future.

131 In vitro nuclear maturation and blastocyst developmental rates after intracytoplasmic sperm injection of equine oocytes held for 24 h at room temperature in Tyrode’s albumin lactate pyruvate-Hepes (TALP-h) or in a commercial embryo holding medium

The interest in equine intracytoplasmic sperm injection (ICSI) for commercial and research applications has rapidly increased. Shipping immature oocytes at room temperature has been proven successful, and to identify the optimal conditions for holding oocytes, several mediums are being tested. The aim of this study was to compare the effect of holding equine oocytes in Tyrode’s albumin lactate pyruvate-Hepes (TALP-h, Bavister and Yanagimachi 1977 Biol. Reprod. 16, 228-237) medium or in commercial embryo holding medium (EHM, Syngro® Holding) on invitro nuclear maturation rates and pre-implantation embryo development after ICSI. Cumulus–oocyte complexes (COCs) were recovered from ovaries of slaughtered mares and assigned randomly in 2-mL cryovials with TALP-h or EHM, with a maximum of 30 oocytes per cryovial. COCs were shipped to the ICSI laboratory at 20 to 25°C for 24 to 28h followed by IVM for 24h in a humidified atmosphere of 5% CO2 in air at 38.5°C. Maturation medium was TCM-199 with 10% fetal bovine serum, 1μL mL−1 insulin-transferrin-selenium, 1mM sodium pyruvate, 100mM cysteamine, and 0.1mg mL−1 FSH. After mechanical cumulus cell removal, nuclear maturation rate was assessed using a stereomicroscope. Oocytes with an intact oolemma and extrusion of the first polar body (PB) were classified as mature, oocytes without a visible PB were considered immature, and oocytes without an intact oolemma were considered degenerate. Matured oocytes were subjected to ICSI without piezo-drill system (one proved stallion) in 20-μL droplets of TALP-h with a 7-μm glass sharp micropipette in an inverted microscope (Nikon Eclipse TE-300 microscope) using hydraulic micromanipulators (Narishige, Medical Systems). Presumptive ICSI zygotes were cultured in DMEM F12/Global Total® with 6% fetal bovine serum for 9 days at 38.5°C in a humidified atmosphere of 5% O2 and 5% CO2 in air. On Day 5 of culture, cleavage was recorded and medium was refreshed. Blastocysts rates were recorded on Day 7 and 9 of culture. Invitro nuclear maturation rates are shown in Table 1. We observed a significantly higher proportion of immature oocytes in the EHM group compared with the TALP-h group. After ICSI of some matured oocytes of each group, no significant differences were observed in cleavage or blastocyst rate (Table 1). Our results suggest that either TALP-h or commercial embryo holding medium are suitable for oocyte shipping and to support blastocyst development after ICSI. Table 1. Invitro nuclear maturation rates and pre-implantation embryo development after intracytoplasmic sperm injection (ICSI) Maturation rates Medium Oocytes Mature [n (%)] Immature [n (%)] Degenerate [n (%)] TALP-h 315 173 (54.9) 26 (8.3)a 116 (36.8) EHM 273 132 (48.4) 55 (20.1)b 86 (31.5) Total 588 305 (51.9) 81 (13.8) 202 (34.4) Embryo development ICSI (n) Cleaved [n (%)] Day 7 Blastocyst [n (%)] Day 9 Blastocyst [n (%)] TALP-h 35 23 (65.7) 7 (20) 9 (25.7) EHM 26 19 (73.1) 3 (11.5) 5 (19.2) Total 61 42 (68.9) 10 (16.4) 14 (23) a,bDifferent superscript letters indicate statistical significance (Fisher’s exact test, P<0.05).

16 Embryo aggregation and adipose-derived mesenchymal donor cells in bovine somatic cell nuclear transfer

Somatic cell nuclear transfer (SCNT) is a powerful tool, but its efficiency remains low. The use of less differentiated donor cells or the embryo aggregation (EA) strategy improves the SCNT rates in several species. It remains unexplored whether the combined use of both strategies results in a synergistic effect that improves SCNT efficiency in bovine. To evaluate that, we assessed the optimal time of EA using IVF embryos (aim 1) and we evaluated whether the use of adipose-derived mesenchymal stem cells (ASC) as donor for SCNT together with EA improves the blastocyst rates and quality (aim 2). For aim 1, cumulus–oocyte complexes (COCs) were collected from slaughterhouse ovaries, invitro matured (TCM-199), fertilized (16×106 spermatozoa mL−1 for 5h) and cultured (synthetic oviductal fluid media in a humidified gas mixture at 39°C). After IVF, the zona pellucida was enzymatically removed and zona-free (ZF) embryos were cultured individually (1X) or 2 embryos placed together within a microwell (2X) (Day 0, n=70). This procedure was performed at Days 3, 4, 5, 6, or 7 (n=76, 78, 94, 96, 90, respectively) and blastocyst rate was assessed at Day 8. Contribution of both embryos to the 2X blastocyst was confirmed by staining Day 0 IVF embryos either with green or red Mitotracker (ThermoFisher Scientific) before EA. For aim 2, fibroblast (FB) and ASC cells were isolated from the skin and subcutaneous adipose tissue of the same adult animal, respectively. Cloned embryos were produced by ZF enucleation, fusion of one ASC or FB cell, and activation with 5μM ionomycin/6-(dimethylamino)purine (6DMAP). After activation, cloned embryos were aggregated (FB2X or ASC2X) or individually cultured (FB1X or ASC1X). Blastocyst rates were recorded at Day 7 of invitro culture. Three biological replicates were evaluated for each aim. Embryo developmental differences were determined using Fisher’s exact test. Relative expression of OCT4, SOX2, and KRT18 was measured by RTqPCR at the blastocyst stage and analysed by Kruskal–Wallis statistical test. Regarding aim 1, no differences for developmental rates were found for Day 0, 3, 4, and 5 groups (57%, 60%, 61.5%, 61%), but the blastocyst rate was only improved in Day 0 and Day 3 relative to their respective 1X controls (Day 0 2X 54.2% vs. Day 0 1X 25.5% and Day 3 2X 52.6% vs. Day 3 1X 25.3%). No aggregation occurred in Day 6 and Day 7 groups. All blastomeres were homogeneously distributed in the 2X blastocyst. Regarding aim 2, no effect of the donor cell was observed on the blastocyst rate (FB1X 26.8%, n=82; ASC1X 21.7%, n=198; FB2X 39.7%, n=126; ASC2X 33%, n=204), whereas EA improved the blastocyst rate of ASC-derived embryos (ASC1X 21.7% vs. ASC2X 33%). Overall, no synergistic effect of the use of both strategies was observed. Relative expression of KRT18 was significantly different between ASC1X and ASC2X embryos. Although OCT4 and SOX2 expression did not differ between groups, EA tended to bring the values closer to that of an IVF embryo. No effect of the donor cell was observed on the embryo relative expression. Our results suggest that EA at Day 0 improves the blastocyst rate in bovine SCNT and IVF embryos. EA of 2 ASC-derived embryos seemed to normalise the embryo quality and may improve post-implantation development.

81 Pronuclear formation and SMARCA4 incorporation after intracytoplasmic sperm injection (ICSI) or assisted ICSI in pig zygotes

Pigs are considered an important experimental model for their biological similarities to humans, including their potential as organ donors in xenotransplantation. Unfortunately, in this species conventional invitro fertilization results in high polyspermic rates. ICSI avoids polyspermy and ICSI-mediated gene edition could be a powerful technique to produce genetically modified pigs. However, ICSI is not yet efficient in pigs. Moreover, the ATP-dependent chromatin remodeller, SMARCA4, translocates to the pronuclei soon after fertilization and its mislocalization or reduction leads to poor embryo development. The aim of this study was to assess whether assisted activation or the use of the piezo drill (PD) during ICSI improves pronuclear (PN) formation rates and to analyse SMARCA4 intensity levels in pronuclei. First, cumulus–oocyte complexes were collected from slaughterhouse ovaries and matured invitro for 44h. Matured and denuded oocytes were subjected to (1) ICSI (n=47), (2) ICSI assisted by PD (ICSIp, n=21), (3) ICSI assisted by electrical activation (ICSIe, n=39), and (4) electrical activation as an haploid parthenogenetic control (HAP, n=21). Presumptive zygotes were fixed for 20min in 4% formaldehyde solution 18h after injection or activation and incubated with SMARCA4 antibody (1:100) and Alexa Fluor (1:1000) as a secondary antibody. Then, the zygotes were classified according to the presence of PN in 2 PN (2-PN), 1 PN with the presence of a semi-condensed or condensed sperm (1-PN), and semi-condensed or condensed sperm with no evidence of PN (no activation). Zygotes that exhibited a different pattern were included in the “other” category. A region of interest was drawn around each PN and the average pixel intensity of SMARCA4 was determined with ImageJ image processing software. Data were analysed by Fisher’s exact test and Kruskal–Wallis test using GraphPad software (GraphPad Inc.). Differences were considered significant at P<0.05. We found no significant differences in 2-PN formation rates among groups after ICSI (ICSI n=16, 34.04%; ICSIe n=10, 25.64%; ICSIp n=6, 28.57%). As expected, the majority of the HAP zygotes exhibited 1 PN (n=14, 66.67%). In contrast, in most of the zygotes of all experimental groups, SMARCA4 was found to be localised in both PN, being absent in polar bodies, metaphase plate, or condensed sperm. Interestingly, out of the total 2-PN porcine ICSI zygotes of all experimental groups (n=25), 7 zygotes (28%) showed clear asymmetric intensity levels between PN. The rest of the ICSI zygotes (n=18, 72%) showed a similar SMARCA4 intensity level between PN. In conclusion, our results suggest that neither the use of piezo drill or electrical activation improves PN formation or SMARCA4 pattern. It remains to be determined whether the asymmetric levels of SMARCA4 between PN observed in some zygotes could be associated with a lower embryo developmental competence.

20 Development and Oct4/Cdx2 gene expression of Puma concolor, Leopardus geoffroyi, and Panthera onca hybrid embryos produced using domestic cat oocytes

The development of assisted reproductive technologies (ARTs) in Felidae species has been proposed to guarantee the genetic viability of species that are on the verge of extinction. Investigation of sperm cryopreservation and IVF have been studied in several Felidae species, but the lack of viable homologous oocytes makes assessment of sperm fertilization capacity after cryopreservation difficult. We propose to evaluate the capability of Puma concolor (Pc), Leopardus geoffroyi (Lg), and Panthera onca (Po) cryopreserved sperm to induce domestic cat oocyte fertilization and subsequent pre-implantation embryo development. Additionally, we evaluated blastocyst quality by analysing the gene expression patterns of pluripotency (Oct4) and differentiation (Cdx2) related markers using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). After ovariectomy, domestic cat (Felis catus, Fc) cumulus–oocyte complexes were matured invitro at 38.5°C in a humidified atmosphere of 6.5% CO2 and 21% O2 for 22h. Cryopreserved sperm from Pc, Lg, and Po were used for heterologous IVF. The sperm was frozen using Tes-Tris–based diluent (TEST), and survival, sperm motility, and acrosome integrity were evaluated. The quality post-thaw was satisfactory. The survival was high, sperm motility (65%) did not decrease during incubation post-thaw, and sperm with intact acrosome was 62% for all species. Briefly, straws were thawed by exposing them to air for 10s and then immersing in a 37°C water bath for 30s. The contents of the straws were poured into prewarmed sterile 1.5-mL microtubes. The sperm suspension was diluted (1:3 vol/vol) by the slow (drop by drop) addition of a modified Tyrode’s solution (Pope et al. 2006 Methods Molec. Biol. 254, 227-244). For IVF, invitro matured oocytes (n=635) were co-incubated with 0.5×105 mL−1 motile spermatozoa at 38.5°C in a humidified atmosphere of 6.5% CO2 and 21% O2 for 18 to 20h. Presumptive zygotes were cultured invitro in 50-µL drops of modified Tyrode’s medium in a humidified gas mixture of 5% CO2, 5% O2, and 90% N2 at 38.5°C. Cleavage was determined 48h post-fertilization and blastocyst stage was evaluated at Day 8 and stored in RNA-Later at −20°C until RT-qPCR analysis. Data were analysed by Fisher’s exact test using GraphPad Prism 6.0 (GraphPad Inc.), and differences were considered significant at P<0.05. We observed significantly lower cleavage rates of Po hybrid (hPo) embryos compared with hPc, hLg, and control Fc embryos (41% vs. 57%, 68%, and 58%, respectively). Additionally, we found that the blastocyst rate was higher using Lg sperm compared with sperm of other groups [hLg (50%) vs. hPc (29%), hPo (21%), and Fc (27%)].

15 Blastocysts altered CDX2 and SOX2 gene expression and pregnancy failure after embryo transfer in yak heterospecific somatic cell nuclear transfer

Heterospecific cloning is a tool for the genetic rescue of endangered animals. Our objective was to evaluate the effects of heterospecific yak (Bos grunniens) cloned embryo aggregation on the expression levels of NANOG, OCT4, CDX2, and SOX2 genes, and to compare with IVF, parthenogenetic zona-free (P-ZF), and homospecific bovine cloned embryos (BB1x). Oocytes were recovered from the ovaries of slaughtered cows and invitro matured for 22h. The zona pellucida was removed by protease treatment and then mature oocytes were enucleated by micromanipulation. Enucleated oocytes were placed in phytohemagglutinin to induce adherence with a somatic donor cell followed by electrofusion (with two 30-µs pulses of 1.2 kV/cm, 0.1s apart). Two hours after fusion, reconstructed embryos were activated using ionomycin followed by 6-(dimethylamino)purine (6-DMAP) treatment for 3h and cultured in synthetic oviductal fluid (SOF) medium for 7 days. The experimental groups were IVF, P-ZF, BB1x, heterospecific yak-bovine cloned embryos (1 embryo per microwell, YB1x), and heterospecific yak-bovine cloned embryos aggregated (2 embryos per microwell, YB2x). In all experimental groups, cleavage and blastocyst rates were assessed 7 days after activation. In addition, 5 blastocysts were pooled for each biological replicate, and pluripotency-specific genes (NANOG, SOX2, CDX2, and OCT4) were analysed by quantitative PCR. Data were analysed by the ΔΔCT method using the geometric mean of ACTB (actin) and GAPDH as internal standard followed by one-way ANOVA. Cleavages rates were significantly lower in the YB1x group compared with the other groups. Moreover, blastocyst rates in YB2x (31.34%, n=67) were significantly higher than in YB1x (13.86%, n=101) and BB1x (13.33%, n=45) groups, but there were no significant differences compared with the IVF (43.82%, n=89) and P-ZF (25%, n=68) groups. In contrast, although no significant differences were observed among groups in the expression of NANOG and OCT4 genes, the expression of CDX2 was lower in YB2x and YB1x blastocysts compared with the BB1X, P-ZF, and IVF (control) groups. In addition, a decrease in SOX2 gene expression was observed in the YB2x and YB1x blastocysts compared with the BB1X group. Blastocysts from YB1x (n=5) and YB2x (n=18) groups were transferred to recipient cows (n=23) on Day 7. Forty days after embryo transfer, presence of uterine fluid was detected by ultrasound in 3 recipient cows (from YB2x), suggesting embryo loss. In concordance with our previous reports, yak heterospecific SCNT blastocysts showed underexpression of CDX2 and SOX2 compared with the overexpression observed for these genes in bovine homospecific SCNT blastocysts. Thus, yak heterospecific SCNT blastocysts may have compromised developmental competence associated with altered expression of CDX2 and SOX2 that cannot be rescued by the aggregation of 2 reconstructed embryos.

19 Improvement of the developmental competence of bovine somatic cell nuclear transfer embryos using latrunculin A during activation

Somatic cell nuclear transfer (SCNT) is an assisted reproductive technology with potential for its application in agriculture, biomedicine, and biotechnology. However, the SCNT efficiency is low. Failure in embryo production by SCNT could be associated mainly with chemical activation treatments or the donor cell type. In this context, we compare the use of latrunculin A (LatA), instead of cytochalasin B during the activation with roscovitine (Rosco), versus the treatment of donor cells with demecolcine (D-cells) followed by activation just with Rosco to compare cloning efficiency. The aim of this study was to evaluate the invitro developmental competence as well as the gene expression pattern of key genes (CDX2, OCT4, SOX2, and NANOG) in blastocysts obtained from the two treatments. To do this, cumulus-oocyte complexes were collected from cow ovaries obtained from slaughterhouses and were IVM for 21h. After cumulus-cell removal, enucleation was performed as described by Gambini et al. (2014 PLoS ONE 9, e110998; https://doi.org/10.1371/journal.pone.0110998). The G0/G1 cells or D-cells were fused to the oocytes. For activation, reconstructed zygotes were treated with 5μM ionomycin for 4min followed by 5-h incubation into different randomly activation groups: D-cells + 50μM Rosco (SCNT-Demec), G0/G1 cells + 50μM Rosco/10μM LatA (SCNT-LatA), and G0/G1 cells + 50μM Rosco/5μgmL−1 cytochalasin B (SCNT-Ctrol). Parthenogenetic controls were also included: Part-Demec, Part-LatA, and Part-Ctrol. Activated oocytes were cultured in synthetic oviductal fluid with amino acids medium until blastocyst stage. Rates of cleavage, morulae, and blastocysts were evaluated at Days 2, 5, and 7 of invitro culture, respectively. Relative abundance of mRNA coding for the four genes was compared between SCNT-Demec, SCNT-LatA, SCNT-Ctrol, and IVF groups by RTqPCR. Data was analysed by Fisher's exact test for invitro culture (P<0.05) or by one-way analysis of variance followed by Tukey post-hoc test (P=0.05). Cleavage rates from SCNT-Demec (n=247, 88%) and SCNT-LatA (n=112, 88%) were significantly higher than those from SCNT-Ctrol (n=123, 76%; Table 1). However, higher blastocyst rates were observed for the SCNT-LatA (n=112, 29%) group than for SCNT-Demec (n=247, 10%) and SCNT-Ctrol (n=123, 14%) (P<0.05). No differences were found for the relative abundance of mRNAs coding for SOX2 and CDX2 between all groups. The NANOG expression was significantly decreased in SCNT-Ctrol and SCNT-LatA compared with IVF embryos (P<0.05). The SCNT-Demec group did not differ from IVF embryos, and OCT4 expression analysis showed no difference among groups. In conclusion, LatA activation improved significantly blastocyst rates, whereas it did not affect gene expression when compared with IVF embryos. Our results suggest that this group could improve full-term developmental efficiency of SCNT embryos. Table 1.Cleavage, morulae, and blastocyst rates among the groups Group1 Treatment n Cleavage (%) Morulae (%) Blastocyst (%) SCNT-Demec Rosco 247 218 (88,26)b 41 (16,60)a 24 (9,72)a SCNT-Ctrol CB/Rosco 123 93 (75,61)a 25 (20,33)a 17 (13,82)a SCNT-LatA LatA 10μM/Rosco 112 99 (88,39)b 42 (37,50)b 33 (29,46)bc Part-Demec Rosco 141 133 (94,33)b 35 (24,82)a 20 (14,18)a Part-Ctrol CB/Rosco 84 76 (90,48)b 22 (26,19)ab 19 (22,62)ab Part-LatA LatA 10μM/Rosco 73 67 (91,78)b 30 (41,10)b 28 (38,36)c a-cStatistical differences between treatments (Fisher's test P<0.05). 1Treatments: donor cells with demecolcine (D-cells) + 50μM roscovitine (Rosco) (SCNT-Demec), G0/G1 cells + 50μM Rosco/10μM latrunculin A (LatA) (SCNT-LatA), and G0/G1 cells + 50μM Rosco/5μgmL−1 cytochalasin B (CB) (SCNT-Ctrol). Parthenogenetic controls were also included: Part-Demec, Part-LatA, and Part-Ctrol.

81 Generation of presumptive domestic cat tetraploid embryos and its application for asynchronic complementation with diploid blastomeres

Tetraploid complementation has been extensively used to verify the pluripotency of stem cells and also for improving placenta formation when tetraploid embryos are aggregated synchronously or asynchronously with diploid (2n) embryos. Generation of tetraploid embryos can be achieved by the electric fusion of a 2-cell embryo. However, the optimal electric intensity pulse to generate tetraploid embryos has not been studied in the feline. The aims of this study were to (1) evaluate the optimal fusion conditions to achieve the highest fusion rate without affecting embryo developmental competence, (2) compare the in vitro development of synchronic and asynchronic aggregated domestic cat IVF embryos, and (3) assess pre-implantation development of embryos generated by asynchronic complementation of presumptive 1-cell tetraploid embryos with diploid blastomeres. Domestic cat cumulus-oocyte complexes were matured in vitro on 21% O2 in air at 38.5°C for 22h. The IVF embryos were generated by co-incubation of in vitro-matured oocytes with 2×106 motile spermatozoa mL−1 on 21% O2 in air at 38.5°C for 18 to 20h. After 24h of IVF, 2-cell embryos were selected. For Experiment 1, membrane fusion of 2-cell IVF embryos (n=164) was performed with two 30-ms DC pulses at different electric field (0.8, 2, 4, and 8 kV/cm) in fusion media (Mannitol, MgSO4, CaCl2, and polyvinyl alcohol). Presumptive fused embryos and nonfused were cultured in vitro in 50-µL drops of modified Tyrode’s medium on 6.5% CO2 in air at 38.5°C (Pope et al. 2006 Methods in Molecular Biology 254, 227-244). Cleavage was determined 24h after pulse. For Experiment 2, zona pellucida-free IVF embryos (n=110) were synchronically (two 4-cell embryos) or asynchronically (one 4-cell embryo and one 2-cell embryo) aggregated in 1 microwell. For Experiment 3, 1-cell presumptive tetraploid embryo (2-cell fused embryo) was asynchronically complemented with a 4-cell embryo (n=38). For all experiments, blastocyst stage was evaluated at Day 8, and embryos presenting more than one structure per microwell were considered non-aggregated. Data were analysed by Fisher’s exact test using GraphPad Prism 6.0 (GraphPad Inc., San Diego, CA, USA), and differences were considered significant at P<0.05. The highest fusion rates (30 and 46%) with the best developmental competence (31 and 46%) were observed with 4 and 8 Kv/cm electric pulses, respectively. Electric fusion did not affect the embryo developmental competence. We observed that synchronic and asynchronic complementation reached similar blastocysts rates (54 and 65%, respectively), indicating that both techniques are suitable for tetraploid embryo complementation. Finally, when presumptive tetraploid embryos were asynchronically complemented with diploid blastomeres, the high blastocyst rate (90%) was obtained from embryos that form only one structure (aggregated embryos). Further experiments will be performed to track the distribution of cells using mitotrackers after complementation using tetraploid IVF and diploid somatic cell nuclear transfer embryos.

77 Development and quality of in vitro bovine hemi embryos produced by blastomere separation and embryo bisection

Bovine monozygotic production of twins became popular in the 1980s as a technique to multiply high value genetics. Moreover, it also became a powerful model for research. Different techniques have been used on bovine embryos obtained by superovulation. In this work, we compared the development rates and quality of monozygotic twin embryos produced by blastomere separation (BS) and embryo bisection (EB) of IVF embryos. To this aim, cumulus-oocytes complexes collected from slaughterhouse ovaries were in vitro matured in TCM 199 containing 10% fetal bovine serum, 10µg mL−1 FSH, 0.3mM sodium pyruvate, 100mM cysteamine, and 2% antibiotic-antimycotic for 24h, at 6.5% CO2 in humidified air and 38.5°C. The IVF was performed with 16×106 spermatozoa per mL for 5h. Afterward, presumptive zygotes were cultured in SOF medium for 7 days at 38.5°C and 5% O2. After 24h of culture, blastomeres of 2-cell stage embryos (N=114) were separated and each one was cultured individually in a microwell for 7 days. Embryo bisection (N=179) was performed manually on Day-7 blastocysts previously depleted of their zonae pellucidae, under stereoscopic microscope. Hemi embryos were cultured for 24h and then twins and single blastocyst rates were calculated. For quality assessment, diameter, total and inner cell mass (ICM) cell number of hemi embryos (BS: 6 couples; ES: 10 couples) and the control group (C: 11) were evaluated. The ICM cell number was measured by immunofluorescence staining using SOX2 antibody and the percentage of ICM and trophectoderm (TE) cells was calculated. The results were analysed using Fisher’s exact test and ANOVA with mean comparison using Tukey’s test (P=0.05). No statistical differences were found in blastocyst rates of twins and single hemi embryos produced by BS (28 and 25%) or EB (23 and 32%). Blastocyst diameter was similar between groups and control. Hemi embryos exhibited lower total and ICM cell number than control (BS: 43±18, EB: 57±14v. C: 93±35 and BS: 16±7, EB: 12±8v. C: 34±19). However, BS hemi embryos had higher ICM and lower TE percentage (40/60%) compared with the EB group (20/80%). The control group did not differ with hemi embryo treatments for ICM and TE (30/70%). Our preliminary results have indicated that although the development rates of hemi embryos produced in vitro were similar between both techniques, blastomere separation generates better quality embryos than blastocyst bisection.

173 Assessment of the first polar body quality and viability in bovine

In female gametes, after the first asymmetric meiotic division, a mature oocyte in metaphase II and a first polar body (PB1) are generated. The PB1 contains one of each pair of homologous chromosomes present in the mature oocyte and its DNA can be used for preconception genetic diagnosis. The PB1 degenerates shortly after extrusion, possibly due to an apoptotic process; however, it has not yet been elucidated in bovine. Therefore, the objective of this study was to evaluate PB1 morphology changes, plasma membrane integrity, and the presence of DNA fragmentation during in vitro maturation (IVM). To this aim, cumulus-oocyte complexes collected from slaughterhouse ovaries were cultured in maturation medium in different groups according to IVM time: 16, 18, 20, 22, 24, and 26h. The PB1 were classified into 5 categories according to their morphology: grade (G)1, round PB1 with intact smooth membrane; G2, round or ovoid PB1 with intact membrane; G3, broken PB1 with a small PB1 fragment; G4, broken PB1 with a big PB1 fragment; and G5, completely damaged PB1. Grades 1 and 2 were considered good quality. Plasma membrane integrity was assessed by propidium iodide (PI) DNA staining; PI is a fluorescent intercalating agent that cannot cross the membrane of live cells. The presence of DNA fragmentation was detected at 16, 22, and 26h by TUNEL assay. Data were analysed by two-way ANOVA and Bonferroni post hoc test using GraphPad Prism 5.0 (GraphPad Inc., San Diego, CA, USA) and differences were considered significant at P < 0.05. Our results (mean%±s.e.m.) showed that significantly more oocytes assessed at 18, 20, 22, and 24h after onset of IVM presented high-quality (G1) PB1 (18 h: 61.5±13.4%, 20 h: 73.5±9.6%, 22 h: 61.0±9.5%, 24 h: 60±5.1%), compared with those assessed at 16 and 26h (43.0±4.7%, 22.3±3.4%, respectively). The percentage of G2 PB1 did not change throughout the period studied (16 h: 34.0±13.5%, 18 h: 29.9±14.1%, 20 h: 22.0±7.1%, 22 h: 26.5±4.2%, 24 h: 23.3±4.9%, 26 h: 21.33±9.9%), but was significantly lower than that of G1 PB1 at 20, 22, and 24h. The proportion of damaged (G5) PB1 started to increase at 24h (14.3±8.6%), being highest at 26h (30.0±10.5%), in parallel with positive PI staining (P<0.05). Moreover, there was a significant increase of PB1 with DNA fragmentation at 26h (82.0±18.0%) compared with 16h (13.9±9.0%) and 22h (2.5±2.5%). Altogether, these findings demonstrate that PB1 remains stable and of good quality between 18 and 24 h; however, after this time, plasma membrane integrity is compromised and the DNA is fragmented, suggesting the occurrence of an apoptotic process. Our results could be helpful to determine the optimal time for using PB1 as a potential donor of genetic material.

201 Testing of single guide RNAs, optimization of transfection, and selection systems for the generation of SRY knockout foetal fibroblast cells

Obtaining male and female cells from a male could have important implications for endangered mammalian species and domestic animal production. Achieving this could constitute a proof of concept of the use of assisted reproduction technologies for the conservation of endangered species. In particular, SRY is the principal male sex determinant gene and is found on the short arm of the Y chromosome. With the introduction of nuclease-mediated genome editing technologies, such as the CRISPR/Cas9 system, it is possible to envision precise DNA targeting in this gene as strategy to manipulate the sex of cell lines. Based on the above, we tested the CRISPR/Cas9 system to later create knockout (KO) cell lines of the SRY gene in bovine. The aim of this work was (1) to test the efficiency of single guide (sg)RNAs designed to target the bovine SRY gene in HEK293T cell line, and (2) to optimize blasticidin concentrations and electroporation conditions in bovine fetal fibroblast (BFF). To test sgRNA efficiency, we used 3 sgRNA designed and tested over the sequence of bovine SRY gene (690bp). The efficiency of each sgRNA was evaluated in a heterologous way by using a modification of pCAG-EGxxFP (plasmid #50716, Addgene, Cambridge, MA, USA) in which we inserted the bovine SRY sequence (NCBI Reference Sequence: NC_016145.1), and that only results in green fluorescent protein (GFP) expression upon cutting by the CRISPR/Cas9 system. We transfected the HEK293T cell line with the following groups to assess the efficiency of 3 sgRNA: (1) btSRY1+Cas9+pCAG-EGSRYFP; (2) btSRY2+Cas9+pCAG-EGSRYFP; (3) btSRY3+Cas9+pCAG-EGSRYFP; (4) PU6-empty+Cas9+pCAG- EGSRYFP; (5) GFP-only control. In addition, 6 blasticidin concentrations (0, 1, 2.5, 5, 10, and 20µg mL−1) and 3 electroporation conditions (Tfx1, Tfx2, and Tfx3) were tested, both in BFF. Electroporation conditions were as follows: Tfx1=1.25 kV cm−1; number of pulses=3; electrode gap=4 mm; interval=100 ms; Tfx2=1.2 kV/cm; number of pulses=4; electrode gap=4 mm; interval=100 ms; and Tfx3=voltage: 350V, LV mode; pulse length=100 µs; number of pulses=4; electrode gap=4 mm; interval=100ms. Statistical analyses were performed using 2-tailed Mann-Whitney tests. Results for sgRNA efficiency, based on GFP expression by counting GFP+ cells under fluorescent microscopy showed that btSRY1 (17%) and btSRY2 (13%) worked significantly better than btSRY3 (1%). The blasticidin selection assay showed that 5, 10, and 20µg mL−1were significantly more lethal than 0, 1 and 2.5µg mL−1, by counting living cells in Neubauer chamber. We chose 5µg mL−1 as the concentration for future experiments. Last, the Tfx2 electroporation protocol (11.34%) was more efficient than the other 2 protocols tested (Tfx1 and Tfx3: 3.48 and 0.86%, respectively), based on the counting of GFP+ cells under fluorescent microscopy. Electroporation of BFF with btSRY1, btSRY2, or both and Cas9 using Tfx2 protocol and molecular characterisation of colonies are currently in progress with the ultimate objective of producing SRY knockout bovine embryos by somatic cell nuclear transfer.

181 Equine androgenic embryos: ability of the equine sperm to develop in a heterospecific ooplasm

Androgenic haploid embryos were originally produced for the study of certain aspects of early embryo development. The generation of androgenic haploid embryos allows us to better understand the complementary parental contribution to embryonic development, and to examine the effects of haploid development on gene expression. Because mare oocytes for research are scarce, the generation of heterospecific androgenic embryos could be useful to study aspects of the biology of early embryo development, or to identify genes and their variations or mutations that are responsible for reproduction-related problems in mares and stallions, which is of interest for the breeding industry. Therefore, the aim of this work was to study the capability of equine sperm to induce embryonic development after injection into an enucleated oocyte from a different species. Porcine cumulus-oocyte complexes (COC) were obtained from abattoir ovaries and placed in 100-µL drops in vitro maturation (IVM) medium for 42h. Cumulus cells were removed with hyaluronidase and vortexing. Then, mature oocytes were subjected to intracytoplasmic sperm injection (ICSI) with stallion frozen-thawed semen (according to Rodriguez et al. 2015). Immediately after the last injection, the zona pellucida of injected oocytes was removed with protease treatment, the oocytes were treated with cytochalasin B, and the metaphase II enucleated with a 20-µm micropipette. Finally, embryos were placed in culture medium (SOF) in plates with the well-of-the-well (WOW) system. As control treatment, non-enucleated pig oocytes were injected with stallion (CE) and boar (CC) semen. At Day 4, embryos were evaluated for cleavage and number of blastomeres, and stained with Hoechst 33342 to verify the presence of DNA in each blastomere under the UV light. Embryos were stored for future PCR studies to validate the presence of equine DNA. Data were analysed by chi-squared test to compare the cleavage of both controls with the androgenic embryos. From a total of 53 androgenic haploid embryos, the cleavage rate was 62% (33/53). Embryos were cleaved in 2 to 4 cells in 72.7%, 5 to 8 cells in 18.2%, and 9+ cells in 9.1% at Day 4. Presence of DNA in all blastomeres was observed in 60.6% (20/33) of the androgenic haploid embryos, while 21.2% (7/33) of the embryos had 10 to 50% of blastomeres with DNA, and 18.6% (6/33) of the embryos did not have DNA in their blastomeres. The ICSI control embryos cleaved in 45.3% (34/75) and 64.9% (98/151) for groups CC and CE, respectively. Cleavage rates in control CE were significantly higher than those in control CC (P<0.004). No statistical difference was observed in the control groups versus androgenic embryos. This preliminary results showed that a heterospecific ooplasm can be successfully used to allow an equine sperm DNA to decondense and to develop, even in absence of the female counterpart. Using this method, copies of a single sperm DNA can be produced to potentially evaluate individual aspects of early embryo development concerning the male contribution. This is the first report of successful androgenic embryos using a heterospecific oocyte to create copies of a horse sperm DNA.

105 Functionality evaluation of two extenders for Leopardus geoffroyi sperm cryopreservation by interspecific IVF with domestic cat oocytes

Even though knowledge in sperm cryopreservation of endangered felids advanced in recent years, very little is known about suitable protocols to cryopreserve sperm from Leopardus geoffroyi (LG). In the present study, sperm obtained by electroejaculation from 5 different males were cryopreserved in either a Tes-Tris- or a lactose-based diluent (Gañan et al. 2009 Theriogenology 72, 341-352) with modifications in the freezing process using a one-step method: straws were placed horizontally on a metal rack, 4cm above the surface of liquid nitrogen in a styrofoam box, and kept for 10min before plunging them in LN. The objectives were to (1) compare in vitro motility and acrosome status of LG sperm cryopreserved in both extenders and (2) test functionality of LG sperm cryopreserved in both extenders through their ability to fertilize mature domestic cat oocytes. Straws were thawed by exposing them to air for 10s and then immersing them in a water bath at 37°C for 30s. The contents of the straws were poured into a sterile 1.5-mL microtube prewarmed to 37°C. The sperm suspension was diluted (1:3 vol/vol) by the slow (drop by drop) addition of a modified Tyrode’s solution. Sperm parameters, percentage of motile spermatozoa, and quality of motility were assessed and sperm motility index (SMI) was calculated as follows: [% motile sperm+(quality×20)]/2. Acrosome integrity was assessed by staining with Coomassie brilliant blue. For IVF, in vitro-matured domestic cat oocytes (n=238 Tes-Tris, n=239 lactose) were co-incubated with 0.5×105 motile spermatozoa/mL under 5% CO2 in air at 38.5°C for 18-20h (Pope et al. 2006 Methods Mol. Biol. 254, 227-244). Presumptive zygotes were cultured in vitro in 50-µL drops of modified Tyrode’s medium at 38.5°C in 5% CO2, 5% O2, 90% N2 atmosphere. Cleavage was assessed 48h postfertilization, and 5% FBS was added at Day 5 of in vitro culture. Blastocyst stage was evaluated at Day 8. Data was analysed by Fisher’s exact test using GraphPad Prism 6.0 (GraphPad Inc., San Diego, CA, USA), significant at P<0.05. Results, mean (±standard error of the means), showed that SMI and acrosome integrity (pre- and post-thawing) were similar for both extenders: prethawed (SMI=56±3.3v. 59±5.5; acrosome integrity=88±3.0% v. 90±2.0%), and post-thawed (SMI=46±5.0v. 44±7.0; acrosome integrity=57±7.5% v. 68±2.4%) Tes-Tris v. lactose, respectively. For IVF, results showed a high cleavage rate in both groups (117/238, 49% v. 117/239, 49%), and a high development to morula (96/238, 40% v. 94/239, 39%) and to the blastocyst stage (61/238, 26% v. 51/239, 21%) for all males Tes-Tris v. lactose, respectively. There were no significant differences between groups at any development stage. In conclusion, we found that both extenders can be used to cryopreserve LG sperm maintaining functional conditions and that fertilizing capacity can be tested using in vitro-matured domestic cat oocytes.

202 Combination of transcription activator-like effector nucleases and homology-independent target integration strategy gene editing technologies for knock-in of recombinant human factor IX Under the β-casein native promoter in bovine IVF embryos

Precise DNA modification is a crucial approach for gene function elucidation, biomedical model development, and transgenic bioreactor generation. In livestock, its application was extremely challenging until the development of engineered nucleases such as zinc-finger nucleases, transcription activator-like effector nucleases (TALEN), and CRISPR/Cas9. Still, precise knock-in (KI) techniques remain inefficient. Recently, the homology-independent target integration (HITI) strategy was developed, allowing precise insertion of transgenes in mammalian cells in an easier fashion. The HITI technique allows site-specific gene insertion by means of cleavage of both the target sequence in the genome and the donor plasmid, followed by DNA repair by nonhomologous end joining. Here, we evaluated the use of TALENs to generate precise knockout (KO) alleles of the β-casein gene (CSN2) by creating small insertions or deletions, and precise insertion of recombinant human factor IX (rhFIX) under bovine CSN2 regulatory sequences, using HITI via cytoplasmic injection of bovine IVF zygotes. First, 2 TALEN pairs (Tn1 and Tn2) targeting exon 2 of bovine CSN2 were designed and their activity was confirmed by primary fibroblasts transfection followed by Surveyor assay at Day 3. Then, both TALEN pairs were evaluated for KO embryo generation by zygote cytoplasmic injection of in vitro-transcribed mRNA encoding for Tn1, Tn2, or a mix containing Tn1+Tn2, at 100ng μL−1. A non-injected control (NIC) was also included. Embryos were in vitro cultured until Day 7 and independently analysed by whole-genome amplification followed by PCR and sequencing. Neither the blastocyst rate [28.8% (n=73), 33.8% (n=71), 32.4% (n=74), and 54.3% (n=127) for Tn1, Tn2, Tn1+Tn2, and NIC, respectively] nor the proportion of edited embryos [44% (n=9), 20% (n=10), and 33% (n=9) for Tn1, Tn2, and Tn1+Tn2, respectively] differed between injected groups (Fisher test, P<0.05), demonstrating efficient editing in bovine embryos by TALENs. Finally, to achieve precise CSN2 KI embryos, the rhFIX open reading frame was PCR amplified with a forward primer containing the Tn1 recognition sequence to obtain the HITI donor and bovine IVF zygotes were co-injected with the Tn1 mRNA and the HITI donor. Embryos were in vitro cultured until Day 7 and individually analysed by nested PCR at both the 5′ and 3′ ends of HITI donor. The PCR-based results indicate HITI donor integration in 7% of embryos analysed (n=14). Sanger sequencing analysis is currently in progress to confirm site-specific integration of HITI and possible rearranged DNA integration in other embryos. To our knowledge, this is the first report on the use of TALEN and HITI for gene modification. Our results indicate that TALEN combined with HITI may constitute an easy strategy for precise production of pharmaceuticals in the milk of livestock.

98 Assessing Endangered Felid Puma concolor Sperm Fertility by In Vitro Fertilization with Domestic Cat Oocytes

The Puma concolor population has been decreasing during the last 30 years. Semen cryopreservation of this species has been accomplished successfully and offers the possibility of preserving endangered species. We previously showed that fertilizing capability of wild felid spermatozoa can be evaluated using intracytoplasmic sperm injection (ICSI) with in vitro-matured domestic cat oocytes (Moro et al. 2014 Reprod. Domest. Anim. 49, 693-700). Due to the lack of homologous oocytes, we evaluated the capability of the Puma concolor sperm to induce domestic cat oocyte fertilization and subsequent pre-implantation embryo development. In the present study, cryopreserved sperm obtained by electroejaculation from five different males were used for IVF of in vitro-matured (IVM) domestic cat oocytes. Straws were thawed by exposing them to air for 10 s and then immersing in a 37°C water bath for 30 s. The contents of the straws were poured into a sterile 1.5-mL microtube pre-warmed to 37°C. The sperm suspension was diluted (1:3 v/v) by the slow (drop-by-drop) addition of a modified Tyrode’s solution. For IVF, IVM oocytes (n = 370) were co-incubated with 0.5 × 105 motile spermatozoa mL−1 in an atmosphere of 21% O2 in air at 38.5°C for 18 to 20 h. Presumptive zygotes were cultured in vitro in 50-μL drops of modified Tyrode’s medium on 6.5% CO2 in air at 38.5°C. Cleavage was determined at 48 h post-fertilization, and 5% FBS was added at Day 5 of in vitro culture. Blastocyst stage was evaluated at Day 8. Results (mean ± SEM) showed a high cleavage rate (179/370, 49.0 ± 4.0%), and a high development to morula stage (137/370, 34.4 ± 7.2%), and to blastocyst stage (94/370, 23.4 ± 4.7%) for all males. These results indicated that Puma concolor spermatozoa can induce domestic cat oocyte activation and development to blastocyst stage in similar rates to domestic cat homologous IVF: IVM oocytes (n = 291), cleavage rate (199/291, 67.1 ± 6.1%), development to morula stage (144/291, 47.8 ± 4.9%), and to blastocyst stage (86/291, 30.1 ± 1.6%). In conclusion, we demonstrated that domestic cat oocyte can be used to evaluated cryopreserve sperm samples from another felid species.

24 Evaluation of Latrunculin A for the Activation of Hand-Made Cloning (HMC) Porcine Embryos

Somatic cell nuclear transfer (SCNT) is an important biotechnological tool. However, production rates of viable offspring remain low. One possible cause of this low efficiency is chromosomal losses during early activation process (Liu et al. 2015 Cell. Reprogram. 17, 463–471). The use of actin inhibitors that block second polar body extrusion during activation protocols might be a strategy to avoid such losses. The objective of this work was to compare the efficiency of the use of 2 actin inhibitors during the activation of hand-made cloning (HMC) porcine embryos. One of the compounds used was latrunculin A (LatA), which joins directly to actin monomers, preventing their assembly to the filaments. The other was cytochalasin B (CB), which is commonly used for activation protocols. It binds to the growing actin filaments and prevents their elongation. For this purpose, in vitro-matured cumulus–oocyte compexes were deprived of their cumulus and zonae pellucidae cells by mechanical and enzymatic treatments. Oocytes were randomly distributed in 2 experimental groups (HMC) and 2 parthenogenetic control groups (PA). For HMC groups, oocytes were bisected using a microblade and the resulting hemioocytes were stained with Hoechst 33342 and observed under UV light to identify those that had lost the metaphase II plate. Adult skin fibroblasts from primary cultures were used as nuclear donors. For nuclear transfer, 2 hemicytoplasts were fused to a donor cell by an electric pulse of 1.42 kV/cm for 30 μs. After 2 h of nuclear reprogramming, the reconstituted embryos were activated by an electric pulse of 1.2 kV/cm for 80 μs and incubated with cycloheximide (CHX, 10 μg mL−1 , 3 h) in combination with one of the actin inhibitors: LatA 2 μM (CHX-LatA goup) or CB 2.5 μg mL−1 (CHX-CB group). The PA groups were subjected to the same activation treatments (PA-CHX+LatA and PA-CHX+CB groups). All embryos were cultured in SOFaa medium, using an adaptation of the well-of-the-well (WOW) system (microwells), in a humidified atmosphere with 5% CO2 in air at 39°C. Cleavage, morulae, and blastocysts rates were evaluated at Days 2, 4, and 7-8, respectively. At least 3 replicates were performed per group. Results are presented in Table 1. Our results demonstrate that the production of embryos by HMC activated with CHX-LatA is as efficient as that with CHX-CB, the protocol currently used in SCNT protocols. Further research is needed to study its effect on chromosomal complements and long-term development. Table 1.Effect of activation with cycloheximide (CHX) and latrunculin A (LatA) on in vitro development of hand-made cloning (HMC) porcine embryos (% ± SD in parentheses)

82 Compensation of the Growth and Development of Individually Transferred Bovine Bisected Embryos

Embryo bisection has been used in cattle for decades to multiply embryos. Recent articles assert that each bisected hemi-embryo continues its growth and differentiation without regenerating the original number of cells, producing smaller embryos. This size difference has been verified until Day 17, when the embryo has already elongated. The objective of this research was to evaluate fetal morphometric differences between embryos and hemi-embryos during the intrauterine period and at birth. For this purpose, 6 Angus cows were superovulated using the FSH/LH protocol (Pluset®, Hertape Calier, Minas Gerais, Brazil) and all were artificially inseminated with the sire ‘Las Lilas 1931 Líder Max’. At Day 7 post-AI, 45 embryos were recovered using a non-surgical technique. In the laboratory, 30 of them were bisected under a stereoscopic magnifier using a portable micromanipulator with a microscale attached. Each hemi-embryo (N = 60) and the remaining integer embryos (N = 15, used as controls) were immediately transferred individually to a recipient. The growth of the fetuses was evaluated ultrasonographically using a Esaote Aquila Pro vet ultrasound (Esaote SpA, Genoa, Italy). Transrectal measurements were performed at 60 and 90 days, recording femur length (only at 60 days), biparietal distance, and abdominal and umbilical cord diameter. At birth, animals were weighed, measured for length and height, and the circumferences of the skull, thorax, abdomen, and metatarsus were recorded. Data were analysed by the t-test implemented in InfoStat Version 1.1 software (https://www.infostat.com.ar/). Table 1 shows the average and standard deviation of all measurements performed. No significant differences (P < 0.05) were observed between hemi-embryos and control at any stage, except for biparietal diameter on Day 90 of gestation, which was not reflected in skull circumference at birth. In conclusion, individually transferred hemi-embryos generated 60-day fetuses with almost no differences in growth and development compared with the control embryos. The compensation phenomenon should have occurred before Day 60 of gestation. Table 1.Mean and standard deviation of all measurements performed on hemi-embryos and control embryos at 60 and 90 days and at birth

26 Drugs that Modify Epigenetics...What do they do to Porcine Clones?

Although somatic cell nuclear transfer (SCNT) technology was developed more than 20 years ago, cloning efficiency remains low. Failures in the reprogramming of the donor cell result in embryos with aberrant epigenetic patterns and low developmental rates. In this study, we assessed whether the use the inhibitor of DNA (cytosine 5) methyltransferase 5-azacitidine (5Aza) combined with the MEK inhibitor in the MAPK pathway PD0325901 (PD) could improve SCNT efficiency in pigs. In vitro maturation of cumulus–oocyte complexes was performed in TCM for 44 h at 39°C under 5% CO2. Cumulus cells and zona pellucida was removed from matured oocytes, followed by enucleation of the metaphase plate previously stained with Hoëchst 33342. Each enucleated oocyte was attached to a donor cell by phytohemagglutinin treatment followed by an electric pulse of 80V for 30 μs. After fusion, reconstituted embryos were activated by an electric pulse followed by an incubation in 2 mM 6-DMAP for 3 h. Cloned embryos were cultured in vitro in a modified well-of-well system in SOF medium, where 3 cloned embryos were placed per microwell (3X). The experimental group 3X + drugs was exposed for the first 3 days to 1 μM PD and 1 μM 5Aza in SOF medium. After washing, embryos were cultured until Day 7 in regular SOF medium. The control group (3X) was cultured in regular SOF medium for 7 days. In vitro embryo developmental rates, gene expression, histone acetylation, and DNA methylation status were studied. The use of epigenetic modifying drugs significantly increased blastocyst rates (40.9% v. 29%; Fisher’s test, P < 0.05) and embryo size (41.46% v. 28.56%; Student’s t-test, P < 0.05) compared with the control group. Regarding gene expression, an increase of the relative expression of genes related to cell differentiation (Igf2 and Cdx2), antiapoptotic pathways (Bcl-xl) and DNA methylation modulation (Mapk1) was observed (P < 0.05). Pluripotency genes Oct4 and Nanog did not show differences between groups. The Bax proapoptotic gene significantly decreased its expression after drug treatment, as did the Klf4 gene (P < 0.05). Results were analysed by Student’s t-test. According to Histone H3K27ac, which is associated with enhancers or gene promoters, its marker was located mainly in the nuclear periphery respect to the control group with a uniform dispersion, indicating that the treatment could be activating certain genes by locating them near the periphery. Histone H3K4me1 was more uniformly localised throughout the nucleus in both groups. The intensity of the fluorescence was measured by quantitative confocal microscopy using a histogram produced by the ImageJ program (National Institutes of Health, Bethesda, MD, USA). Regarding DNA methylation by bisulphite sequencing, the 2 genes studied (Oct4 and DNMT1) showed a higher demethylation status for the treated group. Our results indicate that the combination of 5Aza+PD during early pre-implantation development dramatically increase blastocyst rates and embryo quality. This novel combination could be used as a strategy to improve the efficiency of SCNT in pigs and potentially other animals.

Assessing Tn5 and Sleeping Beauty for transpositional transgenesis by cytoplasmic injection into bovine and ovine zygotes

Transgenic domestic animals represent an alternative to bioreactors for large-scale production of biopharmaceuticals and could also provide more accurate biomedical models than rodents. However, their generation remains inefficient. Recently, DNA transposons allowed improved transgenesis efficiencies in mice and pigs. In this work, Tn5 and Sleeping Beauty (SB) transposon systems were evaluated for transgenesis by simple cytoplasmic injection in livestock zygotes. In the case of Tn5, the transposome complex of transposon nucleic acid and Tn5 protein was injected. In the case of SB, the supercoiled plasmids encoding a transposon and the SB transposase were co-injected. In vitro produced bovine zygotes were used to establish the cytoplasmic injection conditions. The in vitro cultured blastocysts were evaluated for reporter gene expression and genotyped. Subsequently, both transposon systems were injected in seasonally available ovine zygotes, employing transposons carrying the recombinant human factor IX driven by the beta-lactoglobulin promoter. The Tn5 approach did not result in transgenic lambs. In contrast, the Sleeping Beauty injection resulted in 2 lambs (29%) carrying the transgene. Both animals exhibited cellular mosaicism of the transgene. The extraembryonic tissues (placenta or umbilical cord) of three additional animals were also transgenic. These results show that transpositional transgenesis by cytoplasmic injection of SB transposon components can be applied for the production of transgenic lambs of pharmaceutical interest.

186 SUPPLEMENTATION WITH LOW DOSES OF DIMETHYL SULFOXIDE DURING IN VITRO MATURATION RESULTS IN IMPROVED IN VITRO EMBRYO PRODUCTION IN CATTLE

Oocyte in vitro maturation (IVM) is crucial for subsequent in vitro embryo production. It involves acquisition of competence for fertilization and embryo development. Therefore, its optimization could have a direct impact on in vitro embryo development. Dimethyl sulfoxide (DMSO) is commonly used as solvent or vehicle, but also increases the membrane permeability and behaves as a scavenger of cytotoxic free radicals. The aim of this study was to evaluate the effect of DMSO supplementation during bovine oocyte maturation on subsequent in vitro embryo development and to determine the optimal usage dose with no toxic effect. To this aim, cumulus-oocyte complexes were collected from slaughterhouse ovaries and IVM in TCM 199 containing 10% fetal bovine serum, 10 µg mL−1 of FSH, 0.3 mM sodium pyruvate, 100 mM cysteamine, and 2% antibiotic-antimycotic. The oocytes were incubated for 24 h at 6.5% CO2 in humidified air at 38.5°C. For Experiment 1, IVM medium was supplemented with DMSO at concentrations of 0, 0.1, 0.5, 1, or 10% (vol/vol) DMSO (n = 241, 195, 42, 192, 172 oocytes) and IVM rate was determined by presence of the first polar body. For Experiment 2, 0, 0.1, 0.25, 0.5, 0.75, 1, or 10% (vol/vol) DMSO (n = 446, 322, 65, 194, 77, 250, 39 oocytes) was supplemented to IVM medium and cleavage and blastocyst rates were determined to establish the optimal usage dose. In vitro fertilization was performed according to Brackett and Oliphant (1975), with 16 × 106 spermatozoa/mL for 5 h. Afterwards, presumptive zygotes were cultured in SOF for 7 days at 38.5°C and 5% O2. Cleavage and blastocyst rates were determined on Days 2 and 7, respectively. Results were statistically analysed using Fisher’s exact test by GraphPad Prism software (GraphPad Software Inc., La Jolla, CA, USA). Also, the percentage of blastocyst was adjusted to DMSO concentration using the R software quadratic regression model. The optimum usage dose was determined by calculating the maximum of the estimated predictive equation. In vitro maturation in 10% DMSO resulted in significantly lower first polar body extrusion rates (0% = 74%a, 0.1% = 73%a, 0.5% = 83%a, 1% = 66%a, and 10% = 8%b; different letters indicate statistical differences) and lower cleavage rates (0% = 75%a, 0.1% = 77%a, 0.25% = 80%a, 0.5% = 79%a, 0.75% = 78%a, 1% = 77%a, and 10% = 3%b) than the other treatments. Furthermore, blastocyst production was higher for the 0.25 and 0.5% (vol/vol) supplemented DMSO groups (0% = 26%b, 0.1% = 37%ab, 0.25% = 40%a, 0.5% = 41%a, 0.75% = 34%ab, 1% = 23%b, and 10% = 0%c). The predictive equation results indicate that the maximum percentage of blastocysts is obtained with a concentration of 0.458% (vol/vol) of DMSO. In conclusion, DMSO supplementation during IVM of bovine oocytes had a positive effect on in vitro development. Further studies will be carried out to elucidate its mechanism of action.

Efficient edition of the bovine PRNP prion gene in somatic cells and IVF embryos using the CRISPR/Cas9 system

The recently developed engineered nucleases, such as zinc-finger nucleases, transcription activator-like effector nucleases, and clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated nuclease (Cas) 9, provide new opportunities for gene editing in a straightforward manner. However, few reports are available regarding CRISPR application and efficiency in cattle. Here, the CRISPR/Cas9 system was used with the aim of inducing knockout and knock-in alleles of the bovine PRNP gene, responsible for mad cow disease, both in bovine fetal fibroblasts and in IVF embryos. Five single-guide RNAs were designed to target 875 bp of PRNP exon 3, and all five were codelivered with Cas9. The feasibility of inducing homologous recombination (HR) was evaluated with a reporter vector carrying EGFP flanked by 1 kbp PRNP regions (pHRegfp). For somatic cells, plasmids coding for Cas9 and for each of the five single-guide RNAs (pCMVCas9 and pSPgRNAs) were transfected under two different conditions (1X and 2X). For IVF zygotes, cytoplasmic injection was conducted with either plasmids or mRNA. For plasmid injection groups, 1 pg pCMVCas9 + 0.1 pg of each pSPgRNA (DNA2X) was used per zygote. In the case of RNA, two amounts (RNA1X and RNA2X) were compared. To assess the occurrence of HR, a group additionally cotransfected or coinjected with pHRegfp plasmid was included. Somatic cell lysates were analyzed by polymerase chain reaction and surveyor assay. In the case of embryos, the in vitro development and the genotype of blastocysts were evaluated by polymerase chain reaction and sequencing. In somatic cells, 2X transfection resulted in indels and large deletions of the targeted PRNP region. Regarding embryo injection, higher blastocyst rates were obtained for RNA injected groups (46/103 [44.6%] and 55/116 [47.4%] for RNA1X and RNA2X) than for the DNA2X group (26/140 [18.6%], P < 0.05). In 46% (26/56) of the total sequenced blastocysts, specific gene editing was detected. The total number of genetic modifications (29) was higher than the total number of gene-edited embryos, as three blastocysts from the group RNA2X reported more than one type of modification. The modifications included indels (10/56; 17.9%) and large deletions (19/56; 33.9%). Moreover, it was possible to detect HR in 1/8 (12.5%) embryos treated with RNA2X. These results report that the CRISPR/Cas9 system can be applied for site-specific edition of the bovine genome, which could have a great impact on the development of large animals resistant to important zoonotic diseases.

Vesicles Cytoplasmic Injection: An Efficient Technique to Produce Porcine Transgene-Expressing Embryos

The use of vesicles co-incubated with plasmids showed to improve the efficiency of cytoplasmic injection of transgenes in cattle. Here, this technique was tested as a simplified alternative for transgenes delivery in porcine zygotes. To this aim, cytoplasmic injection of the plasmid alone was compared to the injection with plasmids co-incubated with vesicles both in diploid parthenogenic and IVF zygotes. The plasmid pcx-egfp was injected circular (CP) at 3, 30 and 300 ng/μl and linear (LP) at 30 ng/μl. The experimental groups using parthenogenetic zygotes were as follows: CP naked at 3 ng/μl (N = 105), 30 ng/μl (N = 95) and 300 ng/μl (N = 65); Sham (N = 105); control not injected (N = 223); LP naked at 30 ng/μl (N = 78); LP vesicles (N = 115) and Sham vesicles (N = 59). For IVF zygotes: LP naked (N = 44) LP vesicles (N = 94), Sham (N = 59) and control (N = 79). Cleavage, blastocyst and GFP+ rates were analysed by Fisher's test (p < 0.05). The parthenogenic CP naked group showed lower cleavage respect to control (p < 0.05). The highest concentration of plasmids to allow development to blastocyst stage was 30 ng/μl. There were no differences in DNA fragmentation between groups. The parthenogenic LP naked group resulted in high GFP rates (46%) and also allowed the production of GFP blastocysts (33%). The cytoplasmic injection with LP vesicles into parthenogenic zygotes allowed 100% GFP blastocysts. Injected IVF showed higher cleavage rates than control (p < 0.05). In IVF zygotes, only the use of vesicles produced GFP blastocysts. The use of vesicles co-incubated with plasmids improves the transgene expression efficiency for cytoplasmic injection in porcine zygotes and constitutes a simple technique for easy delivery of plasmids.

188 HAPLOID ACTIVATION OF BOVINE OOCYTES WITH IONOMYCIN AND SINGLE OR COMBINED ACTIVATING AGENTS

Haploid activation of bovine oocytes is important for reproductive technologies such as intracytoplasmic sperm injection (ICSI) or somatic cell nuclear transfer (SCNT). Nevertheless, it is still a highly inefficient procedure. The aim of this work was to combine different activation drugs, known to have different targets along the activation cascade, to find a more effective activation protocol. Cumulus-oocyte complexes (COC) were aspirated from slaughtered ovaries and in vitro-matured (IVM) for 22 h. Oocytes were activated with 5 µM ionomycin (IO) for 4 min and then randomly allocated into 1 of the following treatments: 50 µM roscovitine (ROSC), 10 µg mL–1 cycloheximide (CHX), ROSC and 10 µM PD0325901 (ROSC/PD), or CHX and PD (CHX/PD) for 5 h; 15 µM dehydroleucodine (DHL) or DHL and ROSC (DHL/ROSC) for 3 h; DHL and CHX for 3 h followed by 2 h with CHX; 5-min exposure to 7% ethanol 4 h post-IO (ET); or ET followed by ROSC (ET-ROSC). Controls were IO followed by 3 h of exposure to 1.9 mM 6-DMAP with or without a previous 3-h culture in TCM-199 (3 h in DMAP and DMAP, respectively). Embryos were cultured in SOF medium. Pronuclear formation (PN) and second polar body extrusion (2PB) were assessed by 5 µg mL–1 propidium iodide oocyte staining, 17 h after IO. Activation was defined as the presence of at least 1 PN, and 2PB extrusion rate was calculated regardless of the nuclear stage. Data were analysed by Fisher’s Test (P < 0.05). Activation (Table 1) was similar in all groups, with the exception of ROSC/PD and ET-ROSC that were the highest and DHL that was the lowest. Although ROSC or CHX seemed to improve 2PB rate when combined with DHL, cleavage decreased significantly, suggesting DHL itself, or its combination with these drugs, negatively affects embryo development. Group ET showed activation rates comparable to other treatments, but it was not reflected on cleavage, suggesting that ET induces PN formation but it might be inefficient to trigger embryo development. Nevertheless, this observation was not made for ET-ROSC, as it showed a higher cleavage rate than ET and ROSC alone. The mitogen-activated protein kinase (MAPK) inhibitor PD showed different effects when combined with ROSC or CHX, despite that they both act on the mammary fat pad (MPF). In ROSC/PD, a slight improvement was observed on activation and cleavage rates compared with ROSC. Group CHX/PD resulted in a slightly higher 2PB percentage, but a lower activation percentage that derived in a significantly lower cleavage than CHX. In conclusion, ROSC and CHX were the most effective single treatments for haploid activation. Moreover, some combined treatments, namely DHL/ROSC and DHL/CHX, proved to be as effective or better at 2PB extrusion rate, which is the defining feature in haploid activation. Table 1.Activation, second polar body extrusion (2PB) and cleavage of bovine oocytes activated with ionomycin followed by single or combined activating agents1

243 EFFICIENT EDITION OF THE BOVINE PRNP PRION GENE IN SOMATIC CELLS AND IVF EMBRYOS USING THE CLUSTERED REGULARLY INTERSPACED SHORT PALINDROMIC REPEATS (CRISPR)/Cas9 SYSTEM

The rapid introduction of engineered nucleases technologies, such as zinc finger nucleases (ZFN), transcription activator-like effector nucleases (TALEN) and clustered regularly interspaced short palindromic repeats (CRISPR), provides new opportunities for editing genes in a targeted and rather simple fashion. Few reports are available regarding CRISPR efficiency in domestic species. Here, the CRISPR/Cas9 system was employed to develop knockout and knock-in alleles of the bovine PRNP gene, responsible for bovine spongiform encephalopathy (mad cow disease), both in bovine fetal fibroblasts and in IVF embryos. Five sgRNAs were designed to target a 875-bp region within prnp exon 3; all 5 were co-delivered with hCas9 and a homologous recombination vector carrying gfp (pHRegfp). For cells, 3 transfection conditions were compared: 2 μg of hCas9 + 1 μg of sgRNAs mix ± 2 μg pHREGFP (1X) versus 4 μg of hCas9 + 2 μg of sgRNAs mix ± 4 μg of pHREGFP (2X). For IVF zygotes, cytoplasmic injection was conducted with 2 RNA concentrations: (a) 50 ng μL–1 hCas9 RNA + 25 ng μL–1 sgRNAs mix (RNA1X), ±50 ng μL–1 pHREGFP, and (b) 100 ng μL–1 hCas9 + 50 ng μL–1 sgRNAs mix (RNA2X), ±100 ng μL–1 pHREGFP, which were compared with plasmid injections with 100 ng μL–1 pCMVCas9 + 50 ng μL–1 pU6sgRNAs mix (DNA2X), ±100 ng μL–1 pHREGFP. The pHREGFP was always injected as plasmid, under the same conditions as hCas9. DNA from cells was subjected to PCR, Surveyor assay, and sequence analysis. Embryo analysis was conducted on whole-genome-amplified DNA from blastocysts, followed by PCR assays and sequencing. In cells, 2X transfection resulted in indels and amplification of PCR products of lower MW than the wild-type, indicative of the deletion of a part of the targeted PRNP region. However, it was not possible to detect an effect for 1X transfection. For the group transfected with pHREGFP, insertion of a partial EGFP sequence was detected (383 bp). Regarding embryo injection, higher blastocyst rates were obtained in all groups injected with RNA (Table 1). In 48% (21/43) of the sequenced blastocysts specific gene editing was detected (Table 1). Modifications varied among single base pair shift (3/43; 7%), high level of mismatches all over the targeted sequence and vicinity (12/43; 27.9%), full deletion of the 875-bp region (1/43; 2.3%), and partial insertion of 100–498 bp pHREGFP fragments between the HR arms (5/24; 20.8%). Most of these modifications occurred in a mosaic fashion (76%). Results demonstrate that CRISPR/Cas can be efficiently applied for site-specific edition of domestic species genomes. Table 1.In vitro development and gene editing efficiency of embryos injected with plasmids or RNA coding for CRISPR/Cas9 system targeting PRNP

242 HIGHLY EFFICIENT SLEEPING BEAUTY TRANSPOSON-MEDIATED TRANSGENESIS IN BOVINE FETAL FIBROBLASTS

Active transposon-mediated transgenesis is an emerging tool for basic and applied research in livestock. We have demonstrated the effectiveness of a helper-independent piggyBac transposon (pGENIE-3) for gene transfer into the genome of bovine cells (Alessio et al. 2014 Reprod. Domest. Anim. 49, 8). Here, we extend our previous research by examining the suitability of a Sleeping Beauty (SB) transposon-based methodology to deliver transgenes into the genome of bovine fetal fibroblasts (BFF), and the ability of these cells to support in vitro embryo development upon somatic cell nuclear transfer (SCNT). In a first experiment, BFF were chemically cotransfected (JetPRIME®, Polyplus-transfection, Illkirch, France) with a helper plasmid (pCMV-SB100X), which carries an expression cassette for the SB transposase, and the donor vector (pT2/Venus/RMCE) harboring an expression cassette for a fluorescent protein (Venus) flanked by the SB inverted terminal repeats (ITR). Three different ratios of helper and donor plasmids were studied: 1 : 2, 1 : 1 and 2 : 1. After 15 days of culture, the number of fluorescent colonies was counted on an inverted microscope. When vectors were used at ratios of 1 : 1 and 2 : 1, a 78-fold and 88-fold increase (P ≤ 0.05) in the number of fluorescent colonies compared with that in the no-transposase control were calculated. In a second experiment, BFF were chemically cotransfected with the helper vector pCMV-SB100X, and 2 donor transposons: pT2/Venus/RMCE and pT2/SV40-Neo. The former harbors a neo resistance cassette framed by SB ITRs. Different ratios of helper:donors (1 : 1 : 1, 2 : 1 : 1 and 2 : 0.5 : 0.5) were studied, and each ratio compared with a no-transposase control. After 15 days of antibiotic selection, the number of G418-resistant colonies was determined. Every time a functional SB transposase vector was included, the number of fluorescent and G418-resistant colonies was markedly higher compared with that in the respective control without transposase (P ≤ 0.001). Interestingly, all G418-resistant colonies expressed Venus. Molecular characterisation of genomic insertions in 6 monoclonal cell lines was performed by PCR and splinkerette PCR. PCR analysis confirmed presence of the Venus transgene in all cell lines. Splinkerette PCR results revealed at least 15 transposase-catalyzed genomic insertions of the transgene. Individual cells from a polyclonal SB transgenic fibroblast culture were used as nuclear donors to produce zona-free SCNT embryos. Of the reconstructed embryos, 33% reached blastocyst stage and about half of them expressed Venus. In conclusion, SB transposase is able to actively transpose monomeric copies of transgenes into the genome of bovine cells, which can be reprogrammed upon nuclear transfer to generate morphologically normal embryos expressing the transgene of interest.

217 IMPROVEMENT OF INTRACYTOPLASMIC SPERM INJECTION EMBRYO DEVELOPMENT IN BOVINE USING HIGH CYSTEAMINE CONCENTRATION DURING IN VITRO MATURATION AND SPERM CO-CULTURE WITH CUMULUS-OOCYTE COMPLEXES

In bovine, the intracytoplasmic sperm injection (ICSI) technique remains inefficient probably because of low levels of male sperm decondensation. In species with frequent fertilization failure, high cysteamine (Cys) concentration during in vitro maturation (IVM) has been used to improve IVF. Cysteamine, a precursor of glutathione, plays a critical role on sperm decondensation. The aim of this work was to improve ICSI efficiency in bovine by (1) increasing endogenous glutathione levels from oocytes using high Cys during IVM; and (2) incubating sperm with cumulus-oocyte complexes (COC) before ICSI, to mimic the physiological capacitation process. In experiment 1, we tested the effect of high Cys concentrations during IVM over the development of IVF embryos. In experiment 2, we performed ICSI after IVM with 1 mM Cys, based on IVF results. The COC were collected from slaughtered cow ovaries and IVM for 21 h with 10, 1, and 0.5 mM Cys v. 0.1 mM Cys (standard condition). Then, IVF was performed using 16 × 106 sperm mL–1 for 5 h on BO medium. For ICSI, COC were IVM with 1 mM Cys (ICSI 1 mM groups), and sperm used for injection was previously incubated with COC for 3 h (Inc. groups), as was done for IVF. Sham and diploid parthenogenetic (PA Diplo) controls were also included. Metaphase II oocytes were selected for ICSI, and injected oocytes were activated by a 4-min exposure to 5 μM ionomycin, placed on TCM-199 for 3 h (except for PA Diplo) and treated with 2 mM DMAP for 3 h. For ICSI control groups, COC were matured using 0.1 mM Cys. All embryos were cultured in SOF medium. Cleavage and blastocyst rates were evaluated on Days 2 and 7 post-IVF/ICSI, respectively. The total cell numbers of blastocysts were counted at Day 7, after Hoechst 33342 staining. Results are shown in Table 1. In conclusion, an increase of 5- to 10-fold of Cys concentration during IVM was not detrimental for development to blastocyst after IVF. The use of 1 mM Cys during IVM combined with the use of sperm co-cultured wit IVM COC before sperm injection is a good strategy to improve in vitro development of bovine ICSI embryos. Table 1.Effect of 1 mM cysteamine (Cys) during IVM over the development of IVF bovine embryos (top part) and effect of 1 mM Cys during IVM over embryo development of ICSI embryos, using sperm previously incubated (Inc.) with COC (bottom part)

Cheetah interspecific SCNT followed by embryo aggregation improves in vitro development but not pluripotent gene expression

The aim of this study was to evaluate the capacity of domestic cat (Dc,Felis silvestris) oocytes to reprogram the nucleus of cheetah (Ch,Acinonyx jubatus) cells by interspecies SCNT (iSCNT), by using embryo aggregation. Dc oocytes werein vitromatured and subjected to zona pellucida free (ZP-free) SCNT or iSCNT, depending on whether the nucleus donor cell was of Dc or Ch respectively. ZP-free reconstructed embryos were then cultured in microwells individually (Dc1X and Ch1X groups) or in couples (Dc2X and Ch2X groups). Embryo aggregation improvedin vitrodevelopment obtaining 27.4, 47.7, 16.7 and 28.3% of blastocyst rates in the Dc1X, Dc2X, Ch1X and Ch2X groups, respectively (P<0.05). Moreover, aggregation improved the morphological quality of blastocysts from the Dc2X over the Dc1X group. Gene expression analysis revealed that Ch1X and Ch2X blastocysts had significantly lower relative expression of OCT4, CDX2 and NANOG than the Dc1X, Dc2X and IVF control groups. The OCT4, NANOG, SOX2 and CDX2 genes were overexpressed in Dc1X blastocysts, but the relative expression of these four genes decreased in the Dc2X, reaching similar relative levels to those of Dc IVF blastocysts. In conclusion, Ch blastocysts were produced using Dc oocytes, but with lower relative expression of pluripotent and trophoblastic genes, indicating that nuclear reprogramming could be still incomplete. Despite this, embryo aggregation improved the development of Ch and Dc embryos, and normalized Dc gene expression, which suggests that this strategy could improve full-term developmental efficiency of cat and feline iSCNT embryos.

319 APPROACHES TO IMPROVE INTRACYTOPLASMIC SPERM INJECTION MEDIATED TRANSGENESIS AND MAXIMIZE THE USE OF SEX-SORTED SPERM IN BOVINE

Intracytoplasmic sperm injection (ICSI) mediated transgenesis is an effective tool for transgenic animal production. However, ICSI in cattle remains inefficient. In this work, we assayed approaches to improve egfp expressing blastocysts production by ICSI: the sperm pretreatment with heparin and l-glutathione (Hep-GSH), the use of sex-sorted sperm (SS), the refrozen/thawing of SS sperm, and the combination of these. Quality of ICSI blastocysts was analysed by studying the expression of 4 genes, and the rates of DNA fragmentation. Cumulus-oocyte complexes from slaughtered cow ovaries were in vitro-matured for 21 h. Nonsorted (NS) and sex-sorted (SS) frozen straws were thawed. Some of them were incubated with 80 μM Hep-15 mM GSH for 20 h (Hep-GSH+). The Hep-GSH-control group was not pretreated. Semen samples were co-incubated with 50 ng µL–1 of pCX-EGFP for 5 min before ICSI. Moreover, the SS sperm that are usually discarded after ICSI were cryopreserved and used for ICSI after a second thawing (ICSI SS refrozen). The ICSI NS, sham, and diploid parthenogenetic (Diplo PA) controls were included. Oocytes were activated with 5 µM ionomycin for 4 min, TCM-199 for 3 h (except for diploid PA), and 1.9 mM DMAP for 3 h. Cleavage and blastocyst/egfp expression rates were evaluated on Days 2 and 7 post-ICSI, respectively. Results are shown in Table 1. Relative expression of HMGN1, GLUT5, AQP3, and OCT4 genes from ICSI NS Hep-GSH+ and IVF blastocysts were compared by qPCR. Data were analysed by the pair-wise fixed reallocation randomisation test. None of the 4 genes showed differences between groups. The DNA fragmented nucleus index/blastocyst cell numbers were determined by TUNEL assay, not showing differences between groups (Kruskal–Wallis test, P ≤ 0.05). Means ± s.d. were 29 ± 17/91 ± 27 for ICSI Hep-GSH+; 27 ± 15/63 ± 34 for ICSI Hep-GSH–; 28 ± 17/68 ± 17 for ICSI SS, 28 ± 13/75 ± 24 for ICSI SS refrozen; and 21 ± 13/105 ± 59 for IVF SS control. The Hep-GSH pretreatment can increase blastocyst and transgene expressing blastocysts rates after TM-ICSI, except when SS semen is used. Interestingly, the use of SS sperm for ICSI can be maximized by cryopreservation and reuse of discarded sperm cells. The parameters analysed in this work indicate that the proposed approaches do not affect blastocyst quality. Therefore, Hep-GSH pretreatment of NS sperm and refrozen SS sperm could be applied for TM-ICSI in bovine for the production of transgenic animals. Table 1.In vitro development and egfp expression of ICSI embryos fertilized with nonsorted (NS) and sex-sorted (SS) sperm pretreated with Hep-GSH, refrozen, or both

355 COMPARISON OF Tn5 AND SLEEPING BEAUTY SYSTEMS IN BOVINE EMBRYOS AND IN OVINE OFFSPRING

Current techniques for the production of transgenic domestic animals remain inefficient. Only recently, DNA transposons resulted in improved efficiencies for mouse and pig transgenesis. In this work, we evaluated Tn5 and Sleeping Beauty systems for transgenesis in bovine and ovine species. First, both transposon systems were assessed in vitro in bovine embryos employing transposons carrying fluorescent reporter genes. In vitro-produced bovine zygotes were microinjected with either 1) a complex of Tn5:egfp transposon (20 ng μL–1) (protein: transgene with mosaic ends recognised by Tn5, in Mg+2 free medium), or 2) two plasmids carrying Sleeping Beauty 100X (pSB100X, 5 ng μL–1) and pT2/Venus transposon (10 ng μL–1). In vitro results for Tn5 transgenesis in bovine showed that blastocysts, Day 4 egfp embryos and egfp blastocysts rates for the group injected with Tn5:egfp did not differ from the group injected with the egfp transposon alone (73/145, 50%; 86/145, 59%; and 65/145, 45% v. 65/129, 50%; 87/129, 67%; and 57/129, 44%, respectively). For SB transgenesis, blastocysts, D4 Venus embryos, and Venus blastocysts rates did not differ between co-injection of pSB100X and pT2/Venus or injection with pT2/Venus alone (46/99, 46.5%; 64/99, 64.6%; and 33/99, 33.3% v. 41/83, 49.4%; 52/83, 62.7%; and 26/83, 31.3%, respectively). However, Venus intensity in blastocysts was markedly higher for the group co-injected with pSB100X and pT2/Venus respective to pT2/Venus alone. Both systems were assessed in vivo for the production of transgenic lambs employing a functional transposon (hrFIX, recombinant human factor IX driven by a Beta-lactoglobulin promoter). Laparoscopic artificial insemination of donor sheep was performed, and presumptive zygotes were flushed from the oviducts. The microinjections were done identically as described for the bovine embryos. A total of 24 presumptive zygotes were recovered and injected with the Tn5:hrFIX complex. Then, 21 zygotes were transferred to 5 synchronized ewes; one pregnancy of siblings was obtained, and one animal was born. Genomic DNA from skin, placenta, and blood was genotyped by PCR, but the hrFIX gene could not be detected. For the SB approach, 64 presumptive zygotes were recovered from 4 superovulated ewes, microinjected with the SB plasmids, and 21 of them were transferred to 7 oestrous synchronized recipients. The remaining zygotes were cultured in vitro and blastocysts (n = 7) were vitrified. Currently, 3 donor ewes are pregnant, one with siblings (4 total fetuses). Deliveries are expected by the end of August of this year. Our results indicate that both Tn5 and SB systems are capable of resulting in the production of transgene expressing embryos, and the presence of the transposases does not affect embryo viability. However, phenotyping of blastocyst stages does not seem to be predictive for stable transgene integration. The in vivo results will help to better address the suitability of Tn5 and SB approaches for the production of transgenic sheep.

356 SLEEPING BEAUTY TRANSGENESIS IN CATTLE

Transposon-mediated transgenesis is a well-established tool for genome modification in small animal models. However, translation of this active transgenic method to large animals warrants further investigations. Here, the Sleeping Beauty (SB) transposon system was assessed for stable gene transfer into the cattle genome. The transposon plasmids encoded a ubiquitously active CAGGS promoter-driven Venus reporter and a lens-specific α A-crystallin promoter driven tdTomato fluorophore, respectively. The helper plasmid carried the hyperactive SB100x transposase variant. In total, 50 in vitro-derived zygotes were co-injected (Garrels et al. 2011 PLoS ONE 6; Ivics et al. 2014 Nat. Protoc. 9) and cultured up to blastocyst stage (Day 8). Two blastocysts were Venus-positive and were transferred to synchronized heifers, resulting in one pregnancy. The resulting calf was normally developed and vital; however, it died shortly after cesarean section due to spontaneous bleeding from an undetected aneurism. Phenotypic analysis suggested that the calf was indeed double-transgenic, showing widespread expression of Venus and lens-specific expression of tdTomato. Genotyping and molecular analyses confirmed the integration of both reporter transposons and the faithful promoter-dependent expression patterns. Subdermal tissue of an ear biopsy was used to culture fibroblasts, which were employed in somatic cell nuclear transfer experiments. In total, 39 embryos were reconstructed, of which 34 underwent cleavage, and at the end of culture 12 morulas and 12 blastocysts were obtained. Ten of the blastocysts were Venus positive, and embryo transfer of Venus-positive blastocysts is planned. In summary, we showed that the cytoplasmic injection of SB components is a highly efficient method for transgenesis in cattle. Due to the modular composition of SB plasmids, even double transgenic cattle can be generated in a one-step procedure. Importantly, the SB-catalyzed integration seems to favour transcriptionally permissive loci in the genome, resulting in faithful and robust promoter-dependent expression of the transgenes. The transposon constructs carry heterospecific loxP sites, which will be instrumental for targeted insertion of functional transgenes by Cre recombinase-mediated cassette exchange.Financial support of DFG (Ku 1586/3-1), UNRC, CONICET and Agencia Nacional de Promoción Científica y Tecnológica de la Argentina (ANPCyT) is gratefully acknowledged.

273 EFFECT OF IONOMYCIN ASSOCIATED WITH ROSCOVITINE, DEHYDROLEUCODINE, CYCLOHEXIMIDE, OR ETHANOL ON HAPLOID ACTIVATION OF BOVINE OOCYTES

Haploid activation of bovine oocytes after ICSI is a routine procedure. However, embryos frequently contain an abnormal chromosome set as a result of the drugs employed. We compared the efficiency of ionomycin (Io) followed by roscovitine (ROSC), cycloheximide (CHX), ethanol, and dehydroleucodine (DhL) to induce haploid parthenogenetic activation in bovine. Pronuclear (PN) formation, second polar body (2PB) extrusion, embryo development, and ploidy of blastocysts were evaluated. To this aim, COC were aspirated from slaughtered ovaries and IVM for 22 h. Oocytes were activated with 5 µM of Io for 4 min and then randomly allocated into 1 of the following treatments: 25 or 50 µM ROSC or 10 µg mL–1 of CHX for 5 h; 15 or 30 µM DhL for 3 h; or 5 min of exposure to 7% ethanol 4 h post-Io. Controls were Io followed by (1) 3 h in TCM-199 and 3 h in 1.9 mM 6-DMAP (Io-3h-DMAP) and (2) 3 h of exposure to 1.9 mM 6-DMAP (Io-DMAP). Oocytes were cultured in SOF medium. The PN formation and 2PB extrusion were assessed by 5 µg mL–1 of propidium iodide oocyte staining, 17 h after Io. Cleavage, morulae, and blastocyst stages were evaluated at Days 2, 5, and 8 of in vitro development, respectively. Chromosome number of blastocysts was evaluated by Giemsa staining. Data were analysed by Fisher's test (P < 0.05). Rates of 2PB extrusion were 75, 61.1, 60, 56.3, 54.6, and 42.9% for 15 µM DhL (n = 23), 50 µM ROSC (n = 22), Io-3h-DMAP (n = 9), CHX (n = 17), 25 µM ROSC (n = 22), and ethanol (n = 22), respectively, with no differences between groups. A PN was observed in over 81% of the oocytes activated with ethanol, 25 µM ROSC, CHX, 50 µM ROSC, and 15 µM DhL. Lower percentages of 2PB extrusion and PN formation were observed for 30 µM DhL (n = 22; 6.3 and 0%, respectively). The highest cleavage rates were 83.2% for 25 µM ROSC (n = 185), not differing from 78% in Io-DMAP (n = 159). Cleavage rates for 50 µM ROSC (n = 185), CHX (n = 143), and ethanol (n = 74; 80.5, 80.4 and 67.6%, respectively) were not different from Io-3h-DMAP (n = 78; 71.8%) and Io-DMAP. Cleavage rates for 15 µM DhL (n = 70) and 30 µM DhL (n = 93) were the lowest (48.6 and 25.8%). Blastocyst rates were the highest for CHX and 50 µM ROSC, not differing from Io-3h-DMAP (21.7 and 10.8 v. 18%). Very few or no blastocysts were obtained with ethanol, 25 µM ROSC, 30 µM DhL, and 15 µM DhL (4.1, 3.8, 1.1, and 0%, respectively), although ethanol was not different from Io-3h-DMAP. Chromosome number analysis showed that ethanol (n = 2) and CHX (n = 2) resulted in a higher percentage of haploid embryos (50% each), followed by 50 µM ROSC (n = 8), 25 µM ROSC (n = 3), and Io-3h-DMAP (n = 8; 37.5, 33.3% and 12.5%, respectively), although they were not different. Remaining embryos were diploid, aneuployd, or mixoployd. In conclusion, DhL and ROSC proved to be as effective as CHX or ethanol regarding 2PB extrusion and resulting ploidy, defining features when activating oocytes in ART, suggesting they could be efficiently used in bovine to assist ICSI.

6 EQUINE SPERM INDUCES PRONUCLEAR FORMATION BY INTRACYTOPLASMIC SPERM INJECTION IN BOVINE, SWINE, AND FELINE OOCYTES INDEPENDENTLY OF CHEMICAL ACTIVATION ASSISTANCE

Interspecific intracytoplasmic sperm injection (ICSI) is a valuable tool to study early events of fertilization in species for which oocyte availability is reduced. Equine in vitro fertilization remains unsuccessful and ICSI is the technique of choice for the in vitro production of high-value embryos. Therefore, the objective of this study was to evaluate the rate of pronuclear (PN) formation after ICSI with stallion sperm in bovine, swine and feline oocytes with or without chemical activation assistance. Ovaries from cows and pigs were collected at abattoirs whereas gonads from female domestic cats were obtained from ovariectomized animals at veterinary sterilization centers. Cumulus-oocyte complexes were matured in TCM-199 supplemented following standard protocols for each species. ICSI was performed in 100-μL drops of TALP-HEPES, using frozen-thawed semen from one stallion. Spermatozoa were held separate in 3-μL droplets of 7% (vol/vol) polyvinylpyrrolidone, where one of them was immobilized by swiping the injection pipette across its tail, and then injected into the matured oocyte. After ICSI, some oocytes were chemically activated with 5 μM ionomycin for 4 min (cow and cat) or with an electric pulse (sow) followed by 3 h in culture medium to allow extrusion of the second polar body and then exposure to 1.9 mM 6-DMAP solution for 3 h. Embryos were cultured in SOF medium. After 17 h of culture, embryos were stained with propidium iodide to identify the percentage of oocytes activated and with PN. Haploid and diploid parthenogenetic controls were included. Cleavage (48 h after activation) and blastocyst formation (7–8 days) of the partenogenetic control groups were assessed. There were no statistical differences (chi-squared analysis) in PN formation between the activated and nonactivated groups within species. When the activated group was compared between the different species, no differences were observed. However, for the nonactivated group, significant differences were observed between species. The feline oocyte showed the higher percentage of PN and activation, whereas the bovine oocyte exhibited the lower rate of PN formation (cat: 22/27, 81.48%; swine: 19/39, 71.64%; cow:18/63, 43.07%). Our results suggest that the feline oocyte can be used as model to study fertilization events associated with the stallion sperm due to the higher efficiency in supporting PN formation. Our results indicate that the equine sperm is capable of inducing PN formation in these 3 species without further chemical activation assistance.

Evaluation of cheetah and leopard spermatozoa developmental capability after interspecific ICSI with domestic cat oocytes

The ICSI procedure is potentially of great value for felids, and it has not been extensively studied in these species. The objectives of this work were to determine the best conditions for ICSI in the domestic cat (DC) to generate interspecific embryos by injecting cheetah (Ch) and leopard (Leo) spermatozoa. Firstly, DC oocytes were matured with insulin-transferrin-selenium (ITS) or without it (MM) and cultured using atmospheric (21%) or low (5%) oxygen tension after ICSI. The group ITS-5%O2 showed the highest blastocyst rate (p < 0.05), 20.9% vs 8.7%, 7% and 6.5%, for MM-21%O2 , MM-5%O2 and ITS-21%O2 , respectively. The best conditions were used to generate the interspecific embryos, together with ionomycin activation (Io) after ICSI. Interspecific embryos resulted in high rates of blastocysts that were not positively affected by Io activation: 32.6% vs 21% for Ch and Ch-Io, 9.8% vs 21% for Leo and Leo-Io, and 20% vs 17.4% for DC and DC-Io. We also evaluated DNA-fragmented nuclei of experiment 1 and 2 blastocysts, using TUNEL assay. The fragmented nucleus proportion was higher in the ITS-5%O2 group, 67.6%. Surprisingly, interspecific blastocysts showed the lowest fragmented nucleus proportion: 27% and 29.9% for Ch and Leo, respectively. We concluded that ITS and 5%O2 improve blastocyst formation in DC, although with a concomitant increase in DNA fragmentation. Most importantly, cheetah and leopard spermatozoa were able to generate blastocysts without artificial activation, which suggests that developmental capacity of wild felid spermatozoa can be evaluated by interspecific ICSI. This technique should be used to assist wild felid reproduction.

218 IMPROVEMENT OF INTRACYTOPLASMIC SPERM INJECTION MEDIATED TRANSGENESIS (TM-INTRACYTOPLASMIC SPERM INJECTION) USING BULL SPERM PRETREATED WITH HEPARIN AND GLUTATHIONE

TM-intracytoplasmic sperm injection (ICSI) was demonstrated to be an effective technique for the production of transgenic animals. However, this method has not been widely applied for transgenesis in cattle, because of the low embryo developmental rates. This problem may be related to the incomplete sperm decondensation and subsequent pronuclei formation that occurs in cattle after ICSI (Malcuit et al. 2006 Reprod. Fertil. Dev. 18, 39–51). Delgado et al. showed that pretreatment with heparin-sodium salt combined with reduced glutathione (Hep-GSH) could improve bull sperm decondensation (2001 Archives of Andrology 47, 47–58). The objective of this work was to test the use of pretreated sperm with Hep-GSH for TM-ICSI, because an improvement of male pronucleus formation could cause an increase on the frequency of exogenous DNA integration. To this aim, cumulus-oocyte complexes were collected from slaughtered cow ovaries and in vitro matured for 21 h. Frozen sperm from a bull that was previously determined to produce low developmental rates post ICSI and IVF was used. It was thawed and washed twice by centrifuging at 390 × g for 10 min. After that, sperm were incubated with Tris medium supplemented with 80 μM Hep and 15 mM GSH for 20 h. After washing, semen was co-incubated with 50 ng μL–1 of pCX-EGFP plasmid for 5 min on ice and used for ICSI (Hep-GSH ICSI group). An ICSI control group was injected with semen not treated with Hep-GSH. Sham controls were injected with 50 ng μL–1 of pCX-EGFP. Haploid and diploid parthenogenetic controls were also included (Haplo PA and Diplo PA groups). Oocytes were activated by a 4 min exposure to 5 μM ionomycin, placed on TCM-199 for 3 h, and treated with 1.9 mM DMAP for 3 h; Diplo PA were immediately exposed to DMAP after ionomycin treatment. Embryos were cultured in SOF medium. Cleavage and blastocyst rates were evaluated on Days 2 and 7 post ICSI, respectively. Expression of egfp was assayed at Day 4 and at the blastocyst stage. Results: Hep-GSH ICSI group showed higher cleavage rates than ICSI control (68.5%, n = 89 v. 35%, n = 60), and lower than Sham, Diplo PA, and Haplo Pa groups (94% n = 50, 95.1% n = 61, and 85.1% n = 47, respectively; Fisher's exact test, P ≤ 0.05). Although blastocyst rates from ICSI groups did not differ from Haplo PA (21.2%) and Sham groups (8%), Hep-GSH ICSI produced higher rates than ICSI control (19.1 v. 5%). The higher blastocyst rates were observed for Diplo PA (47.5%; P ≤ 0.05). Transgene expression levels at Day 4 were higher for both Hep-GSH ICSI and ICSI control than for Sham control (24.7 and 11.7% v. 0%, respectively; P ≤ 0.05). Rates of egfp expressing blastocysts/injected oocytes were significantly higher for Hep-GSH ICSI than for ICSI and Sham control groups (13.5 v. 1.7 and 0%, respectively; P ≤ 0.05). Conclusions: Pretreatment of bull sperm with Hep-GSH can increase blastocyst rates after ICSI, even when low quality semen is used. Additionally, the employment of Hep-GSH treatment increased rates of transgene expressing blastocysts. It could be a useful strategy for massively implementing TM-ICSI in bovine, for the production of transgenic animals.

41 EFFICIENT STRATEGY FOR INTERSPECIFIC CLONING IN FELIDS

Most of the 36 species of wild felids are at a level of threat, and interspecific SCNT (iSCNT) comes as a strategy to contribute to these species conservation. The aim of this study was to evaluate the effect of embryo aggregation in cheetah (Ch, Acinonyx jubatus), bengal (Ben, a hybrid between Felis silvestris and Prionailurus bengalensis), and domestic cat (DC, Felis silvestris) embryos generated by cloning. DC oocytes were in vitro matured and zona-free SCNT (with DC fibroblasts) or iSCNT (with Ch or Ben fibroblasts) was performed. The reconstructed embryos were activated with 5 μM ionomycin and 1.9 mM 6-DMAP, and cultured in SOF using microwells. Cloned embryos were cultured individually or as 2-embryo aggregates. The experimental groups were Ch1X, Ch2X, Ben1X, Ben2X, and the control groups were DC1X and DC2X. Embryo development was compared by Fisher's exact test (P ≤ 0.05). Embryo aggregation improved cleavage (Day 2) and blastocyst (Day 7) rates per well in all the groups (87.2% v. 96.7%, 83.8% v. 93.3% and 87.6% v. 98.2% for cleavage; and 13.7% v. 28.6%, 33.3% v. 43.8% and 27.4% v. 47.7% for blastocyst, for Ch1X (n = 102), Ch2X (n = 91), Ben1X (n = 154), Ben2X (n = 105), DC1X (n = 113), and DC2X (n = 109), respectively. Moreover, the Ch2X blastocyst rate was statistically similar as the control group DC1X. The mean total cell numbers of the blastocysts obtained were 264 ± 211 and 400.8 ± 97 for Ch1X and Ch2X, 278 ± 62 and 517 ± 104 for Ben1X and Ben2X, 385 ± 127 and 625 ± 183 for DC1X and DC2X, respectively. Although no statistical differences were obtained between the 1X and 2X groups, the 2X groups nearly doubled the average number of cells compared with the 1X groups. Blastocysts were also classified as grade 1 (expanded blastocysts with a well-defined ICM), grade 2 (expanded blastocysts without a well-defined ICM), and grade 3 (not expanded blastocysts). This classification showed an increase in grade 1 DC2X blastocyst compared with DC1X blastocysts (36.7% v. 16.1%), but no differences were observed in the other species. Expression of OCT-4 was assessed by inmunocytochemistry. The cheetah blastocysts markedly over-expressed this protein: the percentage of cells that expressed OCT-4 in Ch1X, Ch2X, Ben1X, Ben2X, DC1X, and DC2X was 88.2, 80.2, 46.3, 45.4, 51, and 47.4%, respectively, with statistical differences among all the groups except Ben1X and Ben2X. The proportion of OCT-4 expressing cells over total cell numbers was analysed by the difference of proportions test (P ≤ 0.05). In conclusion, iSCNT resulted in high rates of blastocyst formation, especially when embryo aggregation was applied. This strategy has not been previously evaluated in felids or iSCNT procedures, and has been demonstrated to improve blastocyst formation, the number of cells in the 3 groups, and the blastocyst quality in the DC. Other pluripotent genes besides OCT-4 should be studied to determine whether the overexpression of this gene in cheetah embryos is the consequence of an inefficient nuclear reprogramming that prevents a correct regulation. Finally, the iSCNT and embryo aggregation could contribute to species conservation in felids.

34 EFFECT OF DONOR CELLS SERUM STARVATION ON THE DEVELOPMENT OF AGGREGATED ZONA FREE CLONED EQUINE EMBRYOS

Donor cell synchronization for nuclear transfer (NT) is one of the crucial steps in the cloning procedure, and it has been shown that different methods affect embryo development. The goal of the present study was to determine the effect of serum starvation in combination with growth to confluence of the somatic donor cells, on in vitro embryo development and quality of aggregated cloned equine embryos. Oocyte collection, maturation, cloning, and activation procedures were performed as described previously by (Gambini et al. 2012 Biol. Reprod. 87, 15). Adult fibroblasts were obtained through culture of minced tissue from neck biopsies of 2 horses. They were cultured in Dulbecco's modified Eagle medium (DMEM) with 10% fetal bovine serum (FBS) and 1% antibiotics. After cell multiplication, they were cryopreserved and stored in liquid nitrogen. After thawing, 2 groups of cell synchronization were established. Group I: growth to confluence for 3 to 5 days before NT followed by serum starvation in DMEM supplemented with 0.5% FBS for 24 h prior to NT; group II: growth to confluence for 3 to 5 days before NT. After activation, reconstructed embryos (RE) were cultured in SOF in the well of well system, placing 3 RE per well. Cleavage and blastocyst formation at Day 7 to 8 were assessed. At Day 7 to 8, embryos were measured and some of each group were fixed with paraformaldehyde to measure DNA fragmentation through the DeadEnd fluorometric TUNEL system (Promega, Madison, WI, USA). In vitro embryo development, on a per embryo and cleaved RE basis, and blastocyst size was compared using the chi-squared test; the proportion test was used for statistical analysis of DNA fragmentation levels (fragmented DNA cells/total cells). There were no statistic differences on cleavage per RE (I: 136/177, 80.2%; II: 142/171, 79.6%), blastocyst rates at Day 7 (I: 29/58, 49.1%, II: 22/56, 39.2%), or on blastocyst size at Day 8. Statistical differences were observed in blastocyst rate at Day 8 (I: 42/58, 72.4%, II: 30/56, 53.5%) and in blastocyst DNA fragmentation levels (I: 202/2464, 8%; II: 173/1440 12%). In conclusion, the restriction of FBS to the cell culture medium 24 h before cloning seams to improve embryo development at Day 8 and also reduces the level of apoptosis in cloned blastocyst, suggesting a better embryo quality. For these reasons, we consider that the addition of the restriction of FBS to the growth to confluence is beneficial for cloned equine embryo development.

3 MEGANUCLEASE TRANSGENESIS IN IVF AND CLONED BOVINE PREIMPLANTATORY EMBRYOS

Techniques available for production of transgenic animals remain inefficient. Recently an effective transgenesis system using I-SceI meganuclease (MegaN) has been described in Xenopus. It consists of MegaN incubation with a pIS-plasmid carrying I-SceI recognition sites-, followed by injection into fertilized egg. Here, we evaluated the MegaN transgenesis system combined with new transgenesis approaches developed by our group. We compared (1) three pIS concentrations incubated or not with MegaN; (2) injection of oocytes at germinal vesicle stage (GV) or of presumptive zygotes post IVF; (3) cloning using donor cells briefly incubated with MegaN or with pIS alone. Conditions for MegaN digestion were 0.5 UI I-SceI + 1x I-SceI buffer +pIS, at 37°C for 45 min. Two pIS were tested. For #1, IS- PaxGFP at 15, 25 and 50 ng μL–1 (15+, 25+ and 50+ for transgene digested by MegaN and 15-, 25- and 50- for transgene not digested). For #2, 50 ng μL–1 of IS-CXEGFP was injected with or without MegaN at GV or after IVF (EGFP+GV, EGFP–GV, EGFP+IVF, EGFP–IVF). Finally, IS-CXEGFP digested or not by MegaN (EGFP+ or EGFP–) and incubated with cumulus cells for 5 min were intracytoplasmatically injected into enucleated oocytes. Embryos were cultured in SOF. Rates of blastocysts and egfp expression were evaluated. Data was analysed by Fisher's test (P < 0.05). In Experiment 1, no differences in blastocyst rates were observed between the 3 IS-PAXGFP concentrations; however, except for 25+ and 50+, blastocysts rates were lower than after IVF [13/69 (18%), 22/98 (22%), 25/89 (28%), 19/91 (20%), 22/80 (27%), 16/71 (22%) and 31/80 (38%) for 15+, 15–, 25+, 25–, 50+, 50– and IVF, respectively]. Egfp expression was higher for 50– than for other groups, except for 25–, which did not statistically differ [9/69 (13%), 12/98 (12%), 19/89 (21%), 24/91 (26%), 16/80 (20%) and 27/71 (38) for 15+, 15–, 25+, 25–, 50+ and 50–, respectively). We observed higher cleavage and blastocyst rates after injection post IVF as compared with GV (P < 0.05). Egfp expression rates were also higher after injection post IVF, but no differences were found between digestion or not with MegaN [19/95 (20%), 23/95 (24%), 79/115 (68%) and 69/119 (57%) for EGFP+GV, EGFP–GV, EGFP+IVF and EGFP–IVF, respectively]. Egfp blastocyst over total blastocyst rates did not differ between injection at GV or post IVF [3/4 (75%), 2/3 (66%), 32/40 (80%) and 35/46 (76%) for EGFP+GV, EGFP–GV, EGFP+IVF and EGFP–IVF, respectively]. After cloning, no differences were found between EGFP+ and EGFP– in blastocysts [10/57 (17%) and 13/70 (18%) for EGFP+ or EGFP–], or in Day 4 egfp expression (23/57 (40%) and 24/70 (34%), respectively]. Expression of blastocysts after cloning was high [9/10 (90%) and 10/13 (76%) for EGFP+ and EGFP–, respectively]. In conclusion, MegaN transgenesis can produce bovine transgene-expressing embryos, although no differences were observed between digestion or not with MegaN. Injection at GV resulted in transgene-expressing embryos. Cloning with donor cells briefly incubated with MegaN resulted in the highest transgenesis rates. MegaN transgenesis could be useful for transgenic live mammal production, as observed in Xenopus.

1 REPLICATION OF SOMATIC MICRONUCLEI IN BOVINE OOCYTES

Microcell-mediated chromosome transfer was developed to introduce a low number of chromosomes into a host cell (Fournier and Ruddle 1977 PNAS 74, 319–323). As a first approach to individual chromosome manipulation, we designed a new technique that consists of injecting a micronucleus into an enucleated oocyte to replicate a low number of chromosomes. Additionally, we studied the capability of such micronuclei to be marked with a transgene. To this aim, micronuclei from adult bovine fibroblasts were produced by incubation in 0.05 μg mL–1 of demecolcine for 48 h followed by 2 mg mL–1 of mitomycin for 2 h. Cells were finally treated with 10 μg mL–1 of cytochalasin B for 1 h. The cumulus-oocyte complexes aspirated from slaughtered cow ovaries were in vitro-matured under standard conditions for 21 h. MII oocytes were mechanically enucleated and injected with somatic micronucleus, which were previously exposed (Mi*) or not (Mi) to 50 ng μL–1 of pCX-EGFP in 10% PVP. Sham and parthenogenetic (PA*) controls were injected with 50 ng μL–1 of pCX-EGFP in 10% PVP. A PA control was also included. After 2 h, oocytes and reconstructed embryos were activated by incubation in 5 μM ionomycin for 4 min + 1.9 mM 6-DMAP for 3 h. Embryos were cultured in SOF. Cleavage stage and egfp expression were evaluated at Day 2 and 4 of IVC, respectively. At Day 2, some Mi and PA embryos were fixed and stained with DAPI. Nuclei were visualised under blue light (488 nm). Cleaved embryos with more than one nucleus were considered to have replicated their DNA. At Day 2, Mi and PA embryos were karyotyped. An IVF group was also included (Brackett and Oliphant protocol, 1975). Briefly, cleaved embryos were treated with 1.25 μg mL–1 of colchicine for 6 h. After Carnoy fixation, they were stained with Giemsa to determine the chromosomal complement of each blastomere. Embryos were classified as follows: less than 15 chromosomes, euploid (1n and 2n) and others (4n, mixoploid and aneuploid). Differences among treatments were determined by Fisher's exact test (P ≤ 0.05). The Mi*, PA* and PA groups showed higher cleavage rates than the Mi treatment [93/108 (86.1%), 111/136 (81.6%) and 160/186 (86%), respectively vs 89/131 (67.9%); P ≤ 0.05]. Cleavage rates of the Sham* group [78/105 (74.3%)] did not differ from Mi and PA* treatments (P ≤ 0.05). Interestingly, a low number of Mi* embryos showed egfp expression (2.2%). Expression levels were significantly lower than those of the PA* group (38.7%) and did not differ from the Sham control (0%; P ≤ 0.05). Although rates of Mi embryos with more than 1 nucleus (63.6%, n = 22) were lower than those for the PA group (100%, n = 28), DAPI staining confirmed replication of micronuclei. Karyotype analysis revealed that 100% of Mi evaluated embryos (n = 11) had less than 15 chromosomes per blastomere (varying from 1 to 13), whereas none of IVF and PA controls showed such results (P ≤ 0.05). Rates of euploid embryos were 75 (n = 20) and 45% (n = 20) for IVF and PA groups, respectively. In conclusion, we have developed a new method for somatic micronuclei, which could be a useful tool to transfer a small number of specific chromosomes and to target transgenesis to a reduced area of the genome.

287 DEVELOPMENT OF DOMESTIC CAT EMBRYOS GENERATED BY INTRACYTOPLASMIC SPERM INJECTION EXPOSED TO IONOMYCIN ACTIVATION AND DIFFERENT CULTURE CONDITIONS

Assisted reproduction techniques in the domestic cat could be successfully applied in endangered wild felids for sustaining genetic biodiversity. One technique with great potential is intracytoplasmic sperm injection (ICSI). The objective of this study was to evaluate the development of domestic cat embryos after ICSI exposed to ionomycin activation, using a free-radical reducer (insulin-transferrin-selenium, ITS) in oocyte maturation and low oxygen tension in culture. Domestic cat ovaries were recovered from cats subjected to ovariectomy and transported to the laboratory within 2 h. They were washed in TALP-H and the oocytes were released from the follicle by repeatedly puncturing and scraping the ovaries. The cumulus–oocyte-complexes selected were in vitro matured in TCM 199 containing 1 IU mL–1 HCG, 10 ng mL–1 ECG, 2.2 mM calcium lactate, 0.3 mM pyruvate, 0.3% BSA, and 3% antibiotic-antimycotic. Matured oocytes were denuded of cumulus cells after 22 h of culture and individually injected with a frozen–thawed epididymal spermatozoon. After ICSI, one group of presumptive zygotes was immediately cultured (ICSI-control group) and another group was activated by incubation with 5 μM ionomycin in TALP-H for 4 min before culture (ICSI-Io group). In both experiments culture conditions were 5% CO2 in air at 39°C. A third group was matured using ITS supplementation, activated with ionomycin after ICSI and then cultured in 5% O2, 5% CO2, and 90% N2 at 39° (ITS-ICSI-Io-O2 group). Control SHAM groups were done for each ICSI treatment: SHAM-control, SHAM-Io, and ITS-SHAM-Io-O2 groups. The culture medium used was SOF and all treatments were analysed by Fisher test (P < 0.05). Non statistical differences were observed among the three ICSI groups in cleavage (day 2), 61.2% (n = 85); 70.7% (n = 58), and 65.5% (n = 58), neither in blastocyst rates (day 8) 10.6%, 10.3%, and 17.2%, for ICSI-control, ICSI-Io, and ITS-ICSI-Io-O2, respectively. In SHAM controls, cleavage rate was low 38.3% (n = 60) and no blastocysts were obtained when no ITS supplementation nor artificial activation was applied (SHAM-control group). However, cleavage improved to 70% (n = 20) and 81% (n = 37) in SHAM-Io and ITS-SHAM-Io-O 2 groups, respectively. Moreover, no statistical differences were observed in these both groups respect to ICSI groups in cleavage neither in blastocyst rates (0% and 5.4%). Our results showed that ITS supplementation during maturation, ionomycin exposure after ICSI, and low oxygen tension in culture did not improve embryo development after ICSI, though allowed parthenogenetic progression to blastocyst stage after SHAM. In conclusion, ICSI without external assistance is a good reproductive technique to be applied in the domestic cat, potentially applicable in wild cat conservation. Dr. Carlos Benaglia, Departamento de Zoonosis, San Martín.

123 AGGREGATION OF CLONED EQUINE EMBRYOS: IMPROVEMENT OF IN VITRO AND IN VIVO DEVELOPMENT

Development of cloned equine embryo is still inefficient. The aim of our study was to assess the aggregation of zona-free genetically identical cloned embryos as a strategy to improve in vitro and in vivo development. Oocyte collection, maturation, cloning, and activation procedures were performed as described by (Lagutina et al. 2007 Theriogenology 67, 90–98). After activation, reconstructed embryos (RE) were cultured in DMEM/F12 with 5% of FBS in the well of well system in 3 different groups: I, only one RE per well; II, two RE per well; and III, three RE per well. Cleavage and blastocyst formation (7 to 8 days) of all experimental groups was assessed. At day 8, some embryos of each group were either fixed to determine Oct-4 expression by immunocytochemistry or transferred transcervically to a synchronized mare. Pregnancies were assessed by ultrasound from 7 days after embryo transfer until day 45 to 50 of pregnancy every 7 to 10 days, and sizes of vesicles and embryos were measured. In advanced pregnant mares, combined thickness of the uterus and the placenta (CTUP) and serum progesterone levels were also determined. The remaining embryos obtained from each group were maintained in culture from day 7 until day 15. Blastocysts growth was determined every 24 h. In vitro development, on a per-well and RE basis, was compared using the chi-square test. Statistical differences were observed in cleavage among groups I and II (P = 0.0088) and groups I and III (P = 0.0004): (I: 91/111, 82%; II: 74/78, 95%; III: 62/62, 100%). Blastocyst rates differed between groups I and III (I: 10/111, 9%; III: 23/62, 37%); no difference was observed with group II (11/78, 14%). There was no difference on blastocyst rates based on the number of aggregated RE (I: 10/111, 9%; II: 11/156, 7%; III: 23/184, 12.5%). The highest pregnancy rate was obtained in group III (I: 1/3, 33%; II: 2/5, 40%; III: 3/4, 75%). Sizes of vesicles and embryos did not differ statistically in such groups. The CTUP and serum progesterone levels were considered normal (<1.2 cm; >8 ng mL–1, respectively) in ongoing pregnancies. We did not observe any differences in Oct-4 expression patterns among groups. Even though statistical differences were found, surprisingly all embryos grew in vitro until day 15 with good rates and the biggest embryo reached 4.25 mm. Embryo aggregation improved in vitro development of equine cloned embryos until day 7, and pregnancies rates were higher. The in vivo sizes of vesicles and embryos were normal for all groups, and in vitro development beyond day 7 showed the high viability of embryos. To conclude, aggregation of cloned equine embryo does not imply extra oocytes because there is no statistical difference in the number of blastocysts obtained per oocytes used to achieve RE. It is also a good strategy to improve in vitro embryo development without alterations on in vivo progress. This is the first report of pregnancies from aggregated equine cloned embryos, and the first healthy cloned foal from South America, confirmed by STR analysis, was born recently derived from group II. Stumpo, Ignacio, Paola Barboza, and Don Antonio staff.

128 MULTIPLICATION OF 8-CELL EMBRYOS BY AGGREGATION OF A SINGLE ENHANCED GREEN FLUORESCENT PROTEIN-LABELED BLASTOMERE WITH PUTATIVE TETRAPLOID EMBRYOS

Isolated blastomeres from 2- and 4-cell embryos are able to generate live offspring. However, the development of each cell of an 8-cell embryo is limited. Tetraploid embryos are used for aggregation with other embryos, embryonic stem cells, and iPS cells, and they are selected against during development of the fetal tissues, but persist in extraembryonic membranes. The objective of this work was to generate a new and simple method for cloning 8-cell bovine embryos and also to explore more efficient methods to multiply transgenic embryos by aggregation of each blastomere from a day-3 embryo with putative tetraploid embryos. To this aim, bovine cumulus–oocyte complexes were in vitro matured in standard conditions and subjected to IVF (day 0) according to Bracket and Oliphant (1975). After IVF, a group of presumptive zygotes was injected with ooplasmic vesicles incubated with 50 ng mL–1 of linearized pCX–egfp. Other group was cultured for 25 additional hours (day 1). At that time 2-cell embryos were electrofused twice at 40V for 25 μs at 100-ms intervals to generate putative tetraploid embryos, visualised as a single blastomere 1 h after the fusion pulse (fused embryos, F). Two aggregation groups were included. A synchronic group (S): IVF for the production of both transgenic embryos and fused embryos was done on the same day; and an asynchronic group (AS): IVF for transgenic embryos took place 1 day before IVF for fused embryos production, so embryos from the A group were younger. Controls consisted of the same S and AS groups, but no fusion was included (NF). On day 3, the enhanced green fluorescent protein [EGFP(+)] blastomeres were selected. Using the well of well system, 1 or 2 embryos of each fusion group (S or AS and F or NF) were removed of their ZP and aggregated in a microwell with one EGFP(+) blastomere from a 5- to 8-cell stage embryo (day 3). In vitro development of the aggregates and green fluorescent protein expression localization of blastocysts were analysed. Blastocysts were obtained for all groups; however, the 2A-F and 2A-NF groups showed the highest rates (44%, P < 0.05) compared with one embryo aggregation. The highest aggregation rates of the EGFP(+) blastomere were observed for 2A-F (67%) and 2A-NF (44%) groups, too. A very poor integration was noted in the 2S-NF (100%), 2S-F (94%), 1A-NF (89%), and 1S-NF (80%) groups. Localised EGFP distribution was also high in the 2A-F group (42%). In all cases, EGFP expression seemed to localise by the inner cell mass. We demonstrated that it is possible to multiply 8-cell embryos of genetic value and also transgenic embryos, in theory reducing mosaicism rates in future offspring. Moreover, our results give rise to the possibility of using EGFP like a reporter gene that could be used to evaluate aggregation efficiency by a fluorescence microscope.

106 EFFECTS OF BONE MORPHOGENETIC PROTEIN 4 (BMP4) AND ITS INHIBITOR NOGGIN ON BOVINE IN VITRO EMBRYO DEVELOPMENT

Bone morphogenetic protein 4 (BMP4) is a member of the BMP family of conserved morphogenes in charge of many events of differentiation (Chen et al. 2004 Growth Factors 22, 233–241) BMP4 is involved in regulation of pluripotency in humans and mice though the role in bovine early embryo development is still undefined. Noggin is a BMP4 inhibitor (Groppe et al. 2002 Nature 420, 636–642) that does not have a specific receptor but functions by directly binding BMP ligands. The objective of this work was to study the effects of BMP4 and Noggin on early bovine embryo development. Cumulus–oocyte complexes (COC) were aspirated from abattoir ovaries and in vitro matured in TCM containing 10% fetal bovine serum (FBS), 2 mM FSH, 20 mM cysteamine, 1% antibiotic- antimycotic (15240, GIBCO, Grand Island, NY, USA) and 0.1 mM sodium pyruvate. Incubation conditions were a 6.5% CO2 humidified atmosphere at 39°C. After 22 h, in vitro fertilization was performed. Briefly, frozen–thawed semen was centrifuged twice at 490 × g and resuspended in B.O. solution to a final concentration of 20 × 106 mL–1 and incubation with COC was performed for 5 h. Presumptive zygotes were randomly cultured in CR2 with 0.3% BSA, free of serum and co-culture (control, n = 217) or supplemented with 100 ng mL–1 of either BMP4 (n = 218) or Noggin (n = 205). Cleavage and blastocyst rates were evaluated at Days 2 and 9 of culture. Blastocysts cell numbers were analysed by nuclear staining with Hoechst 33342. The expression pattern of the transcription factor Oct-4 was studied by immunocytochemistry and confocal microscope analysis in blastocysts. Chi-square tests were applied for cleavage, blastocyst, and hatching rates. One-way ANOVA was used to compare blastocyst cell number and a proportion test was used for Oct-4 expression. For all, P < 0.05 was considered significant. Cleavage rate was significantly lower in the Noggin group compared to control (51.2% v. 62.3%) whereas the BMP group (61.3%) did not differ from control or Noggin groups. Blastocyst rates for the BMP and Noggin groups were statistically lower than control (9.24% and 11.7% v. 20.6%, respectively). Hatching rate for the control group was significantly higher than both BMP and Noggin groups (4.6% v. 1.4% and 0.49%, respectively). Blastocyst cell number did not differ between groups (130, 117, and 128 for control, BMP4, and Noggin groups, respectively). Oct-4 expressing cells over total cell number was lower in BMP (72%; n = 3) and Noggin (72%; n = 3) groups compared to control (83%; n = 3). In our conditions, BMP inhibition with Noggin or addition of exogenous BMP4 negatively affected developmental rates and altered the proportion of pluripotent (Oct-4 positive) cells. Our results demonstrate the importance of a correct balance within the BMP signalling system for proper bovine in vitro embryo development.

2 NEW IVF TRANSGENESIS STRATEGY IN BOVINE USING CELL CYCLE INHIBITORS AND MOSAICISM REVERSION BY CLONING

All the techniques available for transgenic animal production are inefficient. A new transgenic embryo production strategy was developed, consisting on injection of oolema vesicles coincubated with DNA into fertilized embryos. To improve this technique, we evaluated the effects of 1) linear and circular covalently closed plasmid structures; 2) cell cycle inhibitors (DMAP and Dehydroleucodine, DhL) during first pronuclear phase. The effect of the transgene on DNA double strand breaks (DSBs) was also tested. Transgenic blastomeres produced by these strategies were cloned to reverse mosaicism. To this aim, COCs were IVM and subjected to IVF (Bracket and Oliphant, 1975). Then, presumptive zygotes were injected with oolema vesicles incubated with plasmid (OVIP) or with plasmid alone. The plasmid employed was linearized or circular pCX-EGFP. Two treatments were evaluated: 2 mM DMAP (OVIP+DMAP) or 1 uM DhL (OVIP+DhL) for 6 h (15 to 21 h post IVF). Dynamics of egfp expression were daily evaluated. The DNA DSBs were measured by immunocytochemistry against phosphorylated H2AXγ histone. Cloning of IVF transgenic blastomeres was included for the groups OVIP+DMAP, OVIP and for plasmid alone. Rates of egfp expression were higher for linear than circular pCX-EGFP [58/81(71%), 45/68(66%), 51/84(60%), 34/63(53%) v. 24/72(33%), 30/72(41%), 31/93(33%), 18/53(33%), for OVIP+DMAP, OVIP+DhL, OVIP, and plasmid alone respectively; P < 0.05]. As well, egfp expression was delayed after circular plasmids injection (at day 3 post fertilization, a maximum of 7% for circular and over 40% for linear injected groups). For the groups injected with circular pCX-EGFP, there were not differences in egfp blastocysts rates [16/26(61%); 11/23(47%); 13/28(46%), and 5/11(45%) for OVIP+DMAP, OVIP+DhL, OVIP, and plasmid alone respectively]. Except for the group injected with plasmid alone, linear plasmid structure improved egfp blastocysts rates [21/22(95%); 17/22(77%); 22/26(84%) and 10/19(52%) for OVIP+DMAP, OVIP+DhL, OVIP, and Plasmid alone, respectively]. In all cases, DMAP incubation tended to improve egfp rates. Preliminar confocal images showed higher H2AXγ foci number after OVIP injection previous to DMAP or DhL than for DMAP or DhL alone (mean foci number: 122, 72, and 135 for OVIP+DhL, OVIP+DMAP and OVIP v. 38 and 49 for IVF+DhL or +DMAP). Homogenous egfp expression was detected in up to 22% of embryos used as donors for cloning. All cloned blastocysts derived from OVIP+DMAP or OVIP were transgenic (total n = 10). For plasmid alone injection, 20% (1/5) blastocysts lost egfp expression after cloning. Homogenous expression was detected in 100% of OVIP and OVIP+DMAP cloned embryos (33/33 and 40/40), statistically different to plasmid alone (32/42; 76%). In conclusion, the best conditions for IVF mediated transgenesis were OVIP injection, using linearized plasmid structures, followed by DMAP. The presence of the transgene was related to an increase in DNA DSBs. Cloning of egfp blastomeres resulted in mosaicism reversion. This new IVF mediated transgenesis technique represents an interesting alternative for transgenic animal production.