80 REACTIVE OXYGEN SPECIES LEVEL IN PIG EMBRYOS CULTURED IN PRESENCE OF HYALURONAN

It has been reported that during in vitro embryo culture reactive oxygen species (ROS) are generated and are detrimental to embryo development. A recent study (Smorag et al., Proc. 9th ICPR, 2013, 110) demonstrated that an addition of 1 mg mL–1 of hyaluronan (HA) to porcine embryo culture medium improves the development of zygote to blastocyst stage and the quality of produced embryos. Moreover, the embryos cultured with HA showed lower inner mitochondrial membrane potential (Romek et al., 2015 Proc. Symp. Progress in Cell Biology: Mitochondria and Chloroplast, Krakow, 31). Based on the beneficial effect provided by supplementation of HA during embryo culture, we investigated the ROS level in porcine embryos cultured with HA. Porcine zygotes were obtained surgically after flushing the oviducts of superovulated and inseminated gilts. In the experimental group, zygotes were cultured up to the blastocyst stage in NCSU-23 medium supplemented with 1 mg mL–1 of HA (CROMA, Pharma GmbH, Leobendorf, Austria), in an atmosphere containing 5% CO2 in air, at 39°C. In the control group, HA supplementation was omitted. To measure ROS level, embryos at the stages 2–4 and 8–16 cell, morula, and blastocyst (experimental group) and zygote, 2–4 and 8–16 cell, morula, and blastocyst (control group) were labelled with 5 μM CM-H2DCFDA dye (Molecular Probes Inc., OR, USA) for 30 min at 39°C. Labelled embryos were then examined under a Nikon Eclipse microscope with a CCD camera. The total amount of fluorescence emitted from each individual embryos and proportional to the ROS level was measured in arbitrary units. The data were analysed using one-way ANOVA and post-hoc Tukey test. ROS level (mean ± standard error of the mean) in the experimental group was 8.21 ± 2.65 (n = 25), 10.31 ± 3.13 (n = 18), 9.08 ± 2.89 (n = 21), and 20.45 ± 2.38 (n = 31) for 2–4 cell, 8–16 cell, morula, and blastocyst, respectively, whereas in the control group was 9.15 ± 3.43 (n = 15), 7.11 ± 3.13 (n = 18), 8.67 ± 3.04 (n = 19), 11.47 ± 2.46 (n = 29), and 54.74 ± 2.89 (n = 21) for zygote, 2–4 cell, 8–16 cell, morula, and blastocyst, respectively. For experimental and control groups, ROS levels remained unchanged up to morula. On the contrary, at the blastocyst stage from the experimental group ROS level decreased significantly (P ≤ 0.05) in comparison with blastocysts from the control group. In conclusion, porcine blastocysts derived from zygotes cultured with supplementation of 1 mg of HA possess a significantly lower ROS level than blastocysts cultured without HA. This suggests that HA supplementation in culture medium can reduce the ROS level in porcine cultured blastocysts. The project was funded by the National Science Center based on decision number DEC-2012/07/B/NZ9/01326.

79 REACTIVE OXYGEN SPECIES LEVEL IN CULTURED PORCINE EMBRYOS AFTER HIGH HYDROSTATIC PRESSURE

Our recent study (Romek et al., Proc. of 29th Scientific Meeting of A.E.T.E., 2013, 196) demonstrated that high hydrostatic pressure (HHP) decreased the potential of the inner mitochondrial membrane in porcine embryos from morula to blastocyst stage. Therefore, the aim of this study was to find out if HHP treatment of cultured porcine embryos has an effect on production of reactive oxygen species (ROS) in these cells. Gilts were superovulated and inseminated using standard methods. Then zygotes were surgically collected after flushing the oviducts of the donors gilts 22 to 24 h after insemination. Obtained zygotes were cultured in NCSU-23 (North Carolina State University-23) medium up to the blastocyst stage, in an atmosphere containing 5% CO2 in air at 39°C. In the experimental group, embryos at zygote, 2- to 4-cell, 8- to 16-cell, morula and blastocyst stages were treated with 20 MPa of hydrostatic pressure (HHP100, Cryo-Innovation Ltd., Szeged, Hungary) for 60 min at 39°C with an interval of 60 min between HHP treatment and subsequent embryo staining. For the control group of embryos at the same stage of development, the HHP treatment was omitted. An additional group of blastocysts derived after culture was analysed 4 h after the HHP treatment. ROS level was measured using 5 μM CM-H2DCFDA fluorescent dye (Molecular Probes Inc., Eugene, OR, USA). Embryos from the experimental and control groups were stained for 30 min at 39°C and then analysed under a Nikon Eclipse microscope equipped with a CCD camera. The total amount of fluorescence emitted from each individual embryo was measured. The data (in arbitrary unit) were analysed using one-way ANOVA and post-hoc Tukey test. After HHP zygote treatment, the percentage of obtained blastocysts was 67.01, whereas in control group it was 63.95 (P < 0.05). ROS level proportional to the measured amount of fluorescence (mean ± standard error of the mean) was 9.15 ± 2.70 (n = 15), 7.11 ± 2.46 (n = 18), 8.67 ± 2.4 (n = 19), 11.47 ± 1.94 (n = 29), and 54.74 ± 2.28 (n = 21) for zygote, 2- to 4-cell, 8- to 16-cell, morula, and blastocyst stage of the control group, respectively. After HHP treatment, the ROS level was 7.39 ± 2.4 (n = 19), 6.66 ± 2.28 (n = 21), 9.14 ± 2.61 (n = 16), 7.23 ± 2.28 (n = 21), 33.06 ± 2.4 (n = 19) for zygote, 2- to 4-cell, 8- to 16-cell, morula, and blastocyst stage, respectively, and 35.57 ± 2.4 (n = 10) for blastocyst 4 h after HHP treatment. In conclusion, (1) HHP treatment of porcine zygotes improve embryo developmental potential; (2) ROS level in both control and experimental groups remained unchanged up to morula stage, whereas at the blastocyst stage, after HHP treatment ROS level significantly decreased (P < 0.05) in comparison with nontreated blastocysts; (3) HHP treatment on porcine blastocysts resulted in a lowered level of ROS that remained unchanged for 4 h. These results suggest that HHP treatment could improve the quality of cultured porcine blastocysts. The project was funded by the National Science Centre based on decision number DEC-2012/07/B/NZ9/01326.

Optimal concentration of hyaluronan and plant protein in different culture systems for in vitro maturation of bovine oocytes

With a view to search for optimal concentration of hyaluronan (HA) and plant protein (PP) in different culture systems for in vitro maturation of bovine oocytes, cumulus-oocyte complexes (COCs) were matured in vitro in 2 culture systems (first co-cultured with granulose cells and estrus calf serum (ECS) in 2 mL volume, second without co-culture where ECS was replaced by exogenous hormones and BSA or PP in 100 microL dose under mineral oil). Seven types of media were used; 3 in first system and 4 in second system. To evaluate HA and PP effect on oocytes after in vitro culture an estimation of meiosis stage and a level of DNA fragmentation was performed by TUNEL staining. The highest meiotic maturation (84%) was observed in oocytes cultured in medium enriched with ECS in co-culture with granulose cells (1st system). The lowest meiotic maturation was noted in medium with addition of BSA (43%). The addition of HA in the medium enriched with BSA significantly increased the rate of matured oocytes (67%) and also didn't affect the chromatin quality of individual oocytes. The addition of HA to the culture medium supplemented with a PP decreased the rate of matured oocytes to 54% but no statistical differences were noted. The results of the present study showed that HA supplementation didn't have a detrimental impact on oocyte chromatin integrity and improved bovine oocytes' meiotic maturation in medium supplemented only with BSA without co-culture of granulose cells.

Lipid content and cryotolerance of porcine embryos cultured with phenazine ethosulfate

The addition of phenazine ethosulfate (PES) to culture medium was investigated for its effect on pig embryo development, apoptosis, cytoplasmic lipid content and survival after OPS vitrification. Porcine zygotes were cultured in NCSU-23 medium supplemented with 0 (control) or 0.05 microM PES up to the blastocyst stage and were vitrified using OPS technology. Culture of embryos with PES reduced the cytoplasmic lipid content, as measured by fluorescence of blastocysts stained with Nile Red. The survival rate of vitrified blastocysts was slightly enhanced, although not significantly, in the presence of PES compared to the PES-free group (45.2 and 37.9 percent, respectively). These results showed that culturing porcine embryos in medium with PES increased the proportion of morula and blastocyst formation and reduced the index of DNA fragmentation and the cytoplasmic lipid content of cultured blastocysts. However, the use of PES during in vitro culture had limited effect on porcine blastocyst survival after vitrification.

243 APOPTOTIC-LIKE CHANGES AND FERTILITY OF TRANSGENIC FOR HUMAN α1,2-FUCOSYLTRANSFERASE GENE AND NONTRANSGENIC BOAR SPERMATOZOA

In the current study, we used sperm from transgenic boars with a gene construct containing the human α1,2-fucosyltransferase gene that competes with α1,3-galactosyltransferase for the same substrate, N-acetyl lactose amine. A decreased affinity of the anti-Gal antibodies between the human and the pig can reduce the species-specific immunological difference and reduce the risk of xenographic rejection. The objectives of this research were first to find out if the presence of the human α1,2-fucosyltransferase gene (pCMVFUT gene construct) in boars leads to apoptotic-like changes in the ejaculated spermatozoa, and second, to verify the fertilizing capacity of the sperm from transgenic (TG) boars. Six ejaculates were collected from 5 TG and 5 nontransgenic (NTG) boars, both crossbreds of Polish Landrace and Large White aged 21.3 ± 0.8 months. Only ejaculates with at least 70% motile and 80% morphologically normal sperm were used. Fresh semen were diluted to a final concentration of 2.5 × 109 sperm mL–1 in Biosolwens Plus (Biochefa, Sosnowiec, Poland) extender and used for artificial insemination of gilts (5 gilts per 1 ejaculate). All ejaculates were analysed on the day of insemination using 2 fluorescence methods: an assay to assess the early changes in sperm membrane integrity using the combination of fluorophores YO-PRO-1 and propidium iodide (PI; Molecular Probes Inc., Eugene, OR, USA) and an assay for phosphatidylserine (PS) translocation across the plasma membranes using Annexin-V–fluorescein isothiocyanate (FITC) and PI (Roche, Mannheim, Germany). Fluorescent staining was measured by microscopic observation of at least 200 spermatozoa/sample per slide. Results are expressed as means ± SD. Significance of the differences between means was tested by Student’s t-test. Using the YO-PRO-1/PI assay, we observed 3 groups of sperm: apoptotic sperm (3.1 ± 1.5% v. 3.5 ± 1.6%), necrotic sperm (22.2 ± 5.3% v. 19.7 ± 5.1%), and live sperm (74.7 ± 7.8% v. 76.8 ± 5.6%) in TG and NTG boar semen, respectively. Using the Annexin-V–FITC/PI assay, 4 subpopulations were detectable: early apoptotic sperm (2.3 ± 1.3% v. 2.6 ± 1.5%), late apoptotic/early necrotic (16.9 ± 8.4% v. 15.7 ± 5.6%), necrotic sperm (7.7 ± 3.9% v. 6.2 ± 2.9%), and live sperm (73.1 ± 6.1% v. 75.5 ± 5.8%) in TG and NTG boar semen, respectively. The use of both assays yielded no significant differences (P ≥ 0.05) in all detected subpopulations of sperm of TG boars compared with that of NTG boars. Moreover, no differences in conception rate (87.7 and 83.8%) and in the average number of live-born piglets per litter (10.7 and 11.2) were observed after insemination using the semen from TG and NTG boars, respectively. In conclusion, the presence of human α1,2-fucosyltransferase gene in the genome of TG boars did not increase apoptotic-like changes in sperm and did not affect pregnancy rate or litter size. This work was supported by Grant NR 12 0036 06 from the National Centre of Research and Development, Poland.

Lipid content in pig blastocysts cultured in the presence or absence of protein and vitamin E or phenazine ethosulfate

In the present study, total lipid content and content of triglycerides, phospholipids and cholesterol were determined in pig blastocysts cultured in medium without protein, supplemented with bovine serum albumin (BSA), with fetal calf serum (FCS), vitamin E or phenazine ethosulfate (PES). In comparison to blastocysts cultured in NCSU-23 with BSA, we observed a decrease of the total lipid content in PES-treated embryos. Triglyceride content in FCS-, vitamin E- and PES-treated embryos as well as in blastocysts cultured without protein was 81.9%, 70.2%, 57.2% and 74.8% of that found in the blastocysts cultured in NCSU-23 with BSA, respectively. Nevertheless the content of phospholipids remained unchanged. This decrease of triglyceride content in the porcine blastocyst after in vitro culture may be explained by altered lipid metabolism in embryos.

73 LIPID CONTENT AND CRYOTOLERANCE OF PORCINE EMBRYOS CULTURED WITH PHENAZINE ETHOSULFATE

In this study, the addition of phenazine ethosulfate (PES) to culture medium was investigated for its effect on cytoplasmic lipid content in cultured pig embryo and survival after open pulled straw (OPS) vitrification (Vajta et al. 1997 Acta Vet. Scand. 38, 363–366). In addition, in cultured blastocysts, the total cell number per blastocyst and the degree of apoptosis were assessed. Porcine zygotes were cultured up to the blastocyst stage in NCSU-23 medium supplemented with 0 (control, n = 146) or 0.05 μM PES (n = 150). To evaluate the lipid content in embryos, we employed Nile Red (NR), a fluorescent dye specific for intracellular lipids (Genicot et al. 2005 Theriogenology 63, 1181–1194). We measured the amount of fluorescence originating from NR using LSM 510 Meta Zeiss confocal microscope and ImageJ version 1.38x software (National Institutes of Health, Bethesda, MD, USA) and an Integrated Density (ID) parameter. The total amount of fluorescence per embryo (TF), proportional to the amount of lipids, was calculated as the sum of ID measured for all optical slices in each individual z-stack. Blastocysts that were cultured with (n = 48) or without PES (n = 34) were vitrified using OPS technology. Results were analysed using chi-square, Fisher, and Student’s t-tests. The total number of cells and the percentage of TUNEL-positive nuclei of PES-treated blastocysts were significantly different than for the control group (43.6 v. 37.6; P < 0.05 and 1.6 v. 2.9; P < 0.01, respectively). Blastocysts stained with Nile Red fluorescent dye showed intracellular lipid mainly localised to the lipid droplets. They were present both in the embryoblast and trophoblast cells. Mean values of TF estimated for the experimental group was lower by ∼23% than those of the control group. Thereby, blastocysts of the control group possess a higher content of lipids then those found in the experimental group cultured in medium with 0.05 μM PES (P < 0.001). The survival rate of vitrified blastocysts was slightly enhanced, although not significantly, in the presence of PES compared to the PES-free group (44.8 and 37.1%, respectively). These results showed that culturing porcine embryos in medium with phenazine ethosulfate supplementation increased the total cell number per blastocyst and reduced the index of DNA fragmentation of cultured blastocysts. Use of PES in porcine culture medium reduced the cytoplasmic lipid content, as measured by fluorescence of blastocysts stained with Nile Red. However, the use of PES during in vitro culture had a limited effect on porcine blastocyst survival after vitrification. This study was partially supported by Grant NR 12 0036 06 from NCBiR, Poland.

107 DIFFERENCES IN THE INNER MITOCHONDRIAL MEMBRANE POTENTIAL BETWEEN NON-CULTURED AND CULTURED PORCINE EMBRYOS

In comparison to in vivo derived pig embryos, in vitro culture conditions produce embryos with altered metabolic rates of carbohydrates and fatty acids (Romek M et al. 2010 Theriogenology 74, 265–276), which may compromise embryo viability. Because various energy substrates are metabolized via several aerobic pathways leading to generation of the inner mitochondrial membrane potential (ΔΨm), value of ΔΨm is a key indicator of embryo metabolic activity, closely related to oxygen consumption and cellular energy needs. Therefore, the aim of this study was to compare ΔΨm between non-cultured and cultured pig embryos during early development. The non-cultured embryos were obtained from 6-month-old gilts, whereas those derived in vitro were cultured from zygotes to the appropriate stage in North Carolina State University 23 (NCSU-23) medium supplemented with 4 mg mL–1 of bovine serum albumin. The ΔΨm measurements were carried out on both non-cultured and cultured 4 to 8 cell embryos, morulae, blastocysts and late blastocysts. For this, embryos were labelled with 0.5 μM Mito Tracker Orange CMTMRos (MtOR) for 30 min at 39°C and then with 0.5 μM Mito Tracker Deep Red (MtDR) for 30 min at 10°C. Using a LSM 510 Meta Zeiss confocal microscope, we measured the amounts of fluorescence (IMtOR and IMtDR) emitted from embryos and values of ΔΨm were estimated as the IMtOR/IMtDR ratios. The results were analysed by ANOVA and Tukey's test. From the zygote to morula stages, ΔΨm remained unchanged and did not differ between developmentally matched non-cultured and cultured embryos (P < 0.001). The value of ΔΨm increased significantly (P < 0.05) from 0.90 ± 0.26 arbitrary units (a.u.) for morulae to 3.92 ± 0.63 and 2.06 ± 0.38 a.u. for non-cultured and cultured early blastocysts, respectively. Whereas the mean value of ΔΨm was almost 2 times higher in non-cultured than in cultured early blastocysts, the mitochondrial membrane potential was statistically similar (P < 0.05) in the in vivo derived (2.10 ± 0.37 a.u.) compared to cultured (1.87 ± 0.30 a.u.) blastocysts. The lower ΔΨm in cultured early blastocysts may be explained by several-fold higher glucose concentration in NCSU-23 medium than in the oviductal fluid. It was reported that high levels of glucose decreases the Krebs cycle metabolism of pyruvate, glutamine, and glucose, and reduces oxidation rates of fatty acids in cultured pig embryos in comparison with in vivo counterparts. Hence, this impaired metabolism reflected by decreased ΔΨm may be responsible for insufficient energy production and reduced developmental competence of cultured early blastocysts. Therefore, because embryo-cavitation is a critical event in pig development, further effort should be focused on proper blastocyst culture. Research was partially supported by Grant NR 12 0036 06 from NCBiR, Poland.

New technique to quantify the lipid composition of lipid droplets in porcine oocytes and pre-implantation embryos using Nile Red fluorescent probe

The principal objective of this study was to develop a novel method based on confocal microscopy and a solvatochromic fluorescent dye, Nile red (NR) to quantify the main types of lipids in a single mammalian oocyte and embryo. We hypothesize that NR staining followed by the decomposition of NR-spectra identifies and quantifies the triglycerides, phospholipids, and cholesterol in a single oocyte and embryo. We analyzed the lipid droplets in porcine oocytes and pre-implantation embryos up to the hatched blastocyst stage developed in vivo and in cultured blastocysts. The emission spectrum of NR-stained mixture of different lipid types is a convolution of several component spectra. The principal component analysis (PCA) and a multivariate curve resolution-alternating least squares method (MCR-ALS) allowed to decompose the emission spectrum and quantify the relative amount of each lipid type present in mixture. We reported here that the level of the triglycerides, phospholipids and cholesterol in lipid droplets significantly decreases by 17.7%, 26.4% and 23.9%, respectively, from immature to mature porcine oocytes. The content of triglycerides and phospholipids remains unchanged in droplets of embryos from the zygote up to the morula stage. Then the triglyceride level decreases in the blastocyst by 15.1% and in the hatched blastocyst by 37.3%, whereas the amount of phospholipids decreases by 10.5% and 12.5% at the blastocyst and hatched blastocyst stages, respectively. In contrast, the content of cholesterol in droplets does not change during embryo cleavage. The lipid droplets in the blastocyst produced in vivo contain lower amounts of triglycerides (by 26.1%), phospholipids (by 14.2%) and cholesterol (by 34.8%) than those in the blastocyst cultured in NCSU-23 medium. In conclusion, our new technique is suitable to quantify the content of triglycerides, phospholipids and cholesterol in individual mammalian oocytes and embryos. Our findings indicate an important role for lipids during porcine oocyte maturation and early embryonic development, and suggest an altered lipid metabolism in cultured embryos.

Effect of semen quality in transgenic boars on the developmental competence of preimplantation embryos

The aim of this study was to compare the fertilising capacity of sperm from 6 transgenic (TG) and 6 non-transgenic (NTG) boars based on analyses of embryos resulting from insemination with sperm from these particular boars. Expanded blastocysts were collected from five groups of synchronised gilts (six gilts per group) inseminated by TG boars bearing a gene construct containing the human alpha1,2-fucosyltransferase gene and by NTG boars. The ejaculates used for insemination were analysed to detect apoptotic changes using two fluorescence methods: an assay to assess early changes in the membrane integrity of the sperm using the YO-PRO-1 fluorophore and an assay for phosphatidylserine (PS) translocation across the plasma membranes using fluorescein-labelled Annexin-V. Our results, using a combination of YO-PRO-1 and PI fluorophores, revealed no significant differences in the percentage of sperm subpopulations between non-transgenic and transgenic boars (P<0.01). Moreover, the second fluorescent probe also revealed no significant differences between the average values of live (Ann-V(-)/PI(-)), early apoptotic (Ann-V(+)/PI(-)), and late apoptotic/early necrotic sperm (Ann-V(+)/PI(+)) as calculated for TG and NTG boars. Only the percentage of necrotic sperm (Ann-V(-)/PI(+)) was significantly different (P<0.05) between transgenic and non-transgenic boars (3.4%+/-2.7; 7.2%+/-2.1, respectively). The quality of the preimplantation embryos at the blastocyst stage was determined by counting the number of cells, observing a TUNEL-positive reaction and by caspase-3 labelling. We found that expanded blastocysts that were derived from gilts inseminated with TG and NTG boar semen showed almost no DNA fragmentation (80%) and 70% caspase-3 activity. The expanded blastocysts that were derived from gilts inseminated with TG and NTG boar semen did not differ significantly in their DNA fragmentation, and there were no differences in caspase-3 activity. These results revealed a positive correlation between the percentage of blastocysts with TUNEL-positive nuclei and the percentage of blastocysts with caspase-3 activity (r=0.9787; P<0.0001).

147 QUALITY OF PORCINE EMBRYOS CULTURED WITH HYALURONAN

Hyaluronan (HA) is a high molecular weight polysaccharide found in the mammalian follicular, oviduct, and uterine fluids. When HA is added in maturation and culture media, it improves the developmental potential of bovine (Stojkovic M et al. 2002 Reproduction 124, 141-153; Palasz AT et al. 2008 Zygote 16, 39-47), and porcine oocytes (Sato E et al. 1990 Mol. Reprod. Dev. 26, 391-397) and embryos (Miyano T et al. 1994 Theriogenology 41, 1299-1305). Physiological concentration of HA in follicular, oviductal, and uterine fluids of pigs range from 0.04 to 1.83 mg mL-1 (Kano K et al. 1998 Biol. Reprod. 58, 1226-1232). The aim of the present study was to investigate the effect of different concentrations of HA on the development and quality of cultured porcine embryos. Zygotes from superovulated pigs were cultured in vitro in NCSU-23 medium supplemented with BSA and 0 mg mL-1 (control group), 0.25 mg mL-1 (Exp. Group 1), and 0.5 mg mL-1 (Exp. Group 2) of HA (Animal Pharma BV). Experiments were replicated 3 times with 30 to 40 embryos per each treatment group. Embryos were cultured up to the blastocyst stage at 39°C in an atmosphere of 5% CO2 in air, in 4-well plastic dishes, which contained approximately 0.8 mL of the NCSU-23 medium. Embryo quality criteria were cleavage (on Day 2 after in vitro culture), morula (on Day 4) and blastocyst (on Days 6 to 8) rates, total cell number per blastocyst, and degree of apoptosis (on Day 7) assessed by TUNEL method. Results were analyzed by ANOVA test. There was no difference in percentage of cleaved embryos between control and treated Group 1 and 2.The proportion of embryos developed to the morula and blastocyst stage was 80.0 and 60.0% for Group 1 (0.25 mg of HA), 73.7 and 44.7% for Group 2 (0.5 mg of HA), and 73.4 and 46.7% for control, respectively (difference NS). Supplementation with HA did not increase the cell number of the blastocysts but significantly reduced number of apoptotic nuclei from 2.0 for control to 0.7 (P < 0.01) and 0.6 (P < 0.01) for Group 1 and 2, respectively, and apoptotic index from 9.70 for control to 3.01 (P < 0.05) and 1.95 (P < 0.05) for Group 1 and 2, respectively. These results indicate that supplementation of culture medium NCSU-23 with HA improves the quality (assessed by apoptotic index) of pig embryos but does not increase the total cell number in pig blastocysts as reported by Kim HS et al. 2005 (Theriogenology 63, 1167-1180). However, further research to test the HA’s effect on cryopreservation of in vitro and in vivo produced pig embryos are needed.

133 MITOCHONDRIAL ACTIVITY OF IN VIVO DEVELOPING PIG EMBRYOS

Preimplantation pig embryos undergo modifications in their metabolism. Glucose is metabolized via aerobic and anaerobic pathways at early cleavage stages, whereas glycolysis becomes the dominant pathway as development progresses. Moreover, fatty acid oxidation rate increases significantly at the early blastocyst stage. It is possible that mitochondria undergo structural and functional changes in response to altering embryo metabolism. Therefore, the aim of this study was to estimate changes in surface density of inner mitochondrial membranes (Sv) and mitochondrial activity (Av) per unit volume of mitochondria during the maturation of oocyte and early development of porcine embryos derived in vivo. The measurements were carried out on immature and matured oocytes, zygotes, 4 to 8 cell embryos, morula, blastocysts, and late and hatched blastocysts (10 to 39 embryos per stage). To estimate Sv, material was stained with mixture of 1.05 μM 10-N-nonyl Acridine Orange (NOA) and 0.5 μM Mito Tracker Deep Red (MtDR) for 30 min at 20°C. To measure Av, oocytes and embryos were labeled sequentially with 0.5μM Mito Tracker Orange CMTMRos (MtOR) for 30 min at 39°C and 0.5 μM MtDr for 30 min at 20°C. Embryos were then fixed in 3.8% formaldehyde and analyzed by confocal microscopy with a LSM 510 Meta Zeiss. The amounts of fluorescence emitted from embryos labeled as INOA, IMtOR, and IMtDR were measured because these ratios were directly proportional to Sv and Av, respectively. Values Sv and Av calculated for embryos at different stages of development were compared by ANOVA and Tukey’s intervals. During oocyte maturation, Av was low and remained unchanged, whereas Sv significantly decreased (P < 0.05) from 0.26 ± 0.021 f.a.u. (fluorescence arbitrary units) at immature oocytes to 0.11 ± 0.012 f.a.u. at matured oocytes. From the zygote to morula stage, Av was constant and then increased almost 5 times to the value of 0.95 ± 0.036 f.a.u. at the blastocyst stage, whereas late and hatched blastocyst characterized by significantly lower (P < 0.001) Av: 0.51 ± 0.023 and 0.34 ± 0.019 f.a.u., respectively. Surface density of the inner mitochondrial membrane in pig embryo during cleavage significantly (P < 0.05) increased from 0.16 ± 0.013 f.a.u. at zygote to 0.35 ± 0.020 and 0.75 ± 0.059 f.a.u. at morula and blastocyst, respectively. In conclusion, during the early stage of pig embryo development, mitochondria undergo structural and functional changes. Results demonstrate that the area density of inner mitochondrial membranes increases earlier (at 4 to 8 cell stages) than mitochondrial activity, which increase not before blastocyst stage. Furthermore, after blastocoel formation, when energy requirement is significantly lower, Av decrease but Sv remain constant.

Assessment of plasma membrane and chromatin structure of sperm from transgenic and non-transgenic boars

The aim of this study was to determine the apoptotic changes and chromatin damage in non-transgenic and transgenic boars carrying the human alpha1,2-fucosyltransferase gene. Five ejaculates were collected from six transgenic (TG) and six non-transgenic (NTG) boars. Five ejaculates were collected from six transgenic (TG) and six non-transgenic (NTG) boars both crossbreds of Polish Landrace and Large White. Two fluorescence methods were employed to measure apoptosis: an assay to assess the early changes in sperm membrane integrity using fluorophore YO-PRO-1 and an assay for phosphatidylserine (PS) translocation across the plasma membrane using fluorescein-labeled Annexin-V. The chromatin damage was assessed based on the sperm chromatin structure assay method. No significant differences in the proportion of all detected subpopulations of spermatozoa were found between TG and NTG boars. Similarly, the analysis of the chromatin structure revealed no statistical differences in the sperm chromatin damage between TG and NTG boars. In conclusion, the presence of the human alpha1,2-fucosyltransferase gene in the genome of TG boars did not cause any spermatogenesis process disturbances leading to the increased production of apoptotic spermatozoa. Moreover, the low level of sperm with damaged chromatin in TG boars confirms the high stability of the spermatogenesis process in the TG boars analyzed.

113 EFFECT OF PLANT PROTEIN ON DEVELOPMENT AND QUALITY OF CULTURED IN VITRO PORCINE ZYGOTES

Basic culture media are usually supplemented with serum albumin or serum, which contain amino acids that play an important role as energy sources, osmoregulators, and pH stabilizers. However, the presence of undefined serum in culture media introduces a variation from batch to batch and increases viral or prion contamination risk. The aim of the present study was to investigate the possibility of using plant protein substitute (PP) in place of bovine serum albumin (BSA) during in vitro culture of porcine zygotes. The PP is a mixture of several plant proteins and soya lecithin prepared using a high pressure homogenization process. The experiment was done on pig zygotes obtained surgically from superovulated gilts at 24–26 h after insemination. Morphologically normal zygotes were cultured in vitro in 5% CO2 in air at 39° in NCSU-23 medium supplemented with: 0.002 g mL–1 (group 1), 0.004 g mL–1 (group 2), 0.008 g mL–1 (group 3) PP or 0.004 g mL–1 BSA (control group). Embryo quality criteria were developmental competence (cleavage, morula and blastocyst rates), total cell number per blastocyst and degree of apoptosis as assessed by TUNEL method. Results were analyzed by Chi-square test. There were no differences in cleavage rates on Day 2 between zygotes cultured in NCSU-23 medium supplemented with PP (86.0, 88.0, 84.8; group 1 to 3, respectively) and BSA (91.0%, control group). Culture with 0.008 g mL–1 PP increased morula (85.7%) and blastocyst (69.2%) production as compared with control (75.0% and 56.3%, respectively; P < 0.05) and 0.002 g mL–1 PP (79.5% and 51.8%, respectively; P < 0.05). The mean number of cells in Day 7 blastocysts cultured in NCSU-23 medium + 0.004 g mL–1 BSA was lower (P < 0.05) than in NCSU-23 + 0.004 g mL–1 PP (39.1 v. 43.7, respectively). The blastocysts cultured in NCSU-23 medium + 0.002 g mL–1 PP had higher average number of apoptotic nuclei (13.0) as compared with the control (6.5) and 0.004 g mL–1 PP (6.9). In conclusion, this study suggest the positive effect of PP on development in vitro of porcine zygotes to the morula/blastocyst stage. However, further studies are required to determine the quality of the embryos cultured with PP. This study was supported by Scientific Net of Animal Reproduction Biotechnology.

51 DEVELOPMENT OF EQUINE CLONED EMBRYOS DERIVED FROM IN VITRO-MATURED OOCYTES RECEIVING ADULT DERMAL FIBROBLAST CELL NUCLEI

The purpose of our study was to determine the in vitro developmental competences of equine NT embryos reconstructed with adult dermal fibroblast cells. Frozen/thawed fibroblast cells, whose mitotic cycle had been synchronized at G1/G0 stages through a contact inhibition of their migration and proliferative activity under total confluency, were used as a source of nuclear donor cells in the somatic cell cloning procedure. In vitro-matured oocytes were used as recipient cells for fibroblast cell nuclei. The compact cumulus–oocyte complexes (cpCOCs) were collected from abattoir-derived mare ovaries and selected for in vitro maturation. The cpCOCs were cultured in TC-199 medium supplemented with 5 mU mL–1 follicle-stimulating hormone (FSH), 10% fetal bovine serum (FBS) and 75 μg mL–1 kanamycin monosulfate (kanamycin A) for 30 h at 38.2°C in a 100% water-saturated atmosphere of 5% CO2 and 95% air. Cumulus-denuded in vitro-matured oocytes were incubated in the maturation medium supplemented with 0.4 μg mL–1 demecolcine for 40 min. The treated oocytes were subsequently transferred into TC-199 medium containing 4 mg mL–1 BSA-V and 5 μg mL–1 cytochalasin B. Metaphase chromosomes, which had been allocated into the chemically-induced protrusion of the plasma membrane, were removed microsurgically. The chemically-assisted enucleation was accomplished by gently aspirating the ooplasmic cone, which contained the condensed chromosome mass, with the aid of a beveled micropipette. The single nuclear donor cells were inserted into perivitelline space of previously enucleated oocytes. Fibroblast cell-ooplast couplets were fused with two consecutive DC pulses of 2.4 kV cm–1 for 30 μs. After a 1.5-h delay, nuclear transfer-derived oocytes were chemically activated by exposure to 5 μm L–1 calcium ionomycin for 5 to 7 min, followed by their incubation in B2 medium with addition of 2 mm L–1 6-dimethylaminopurine (6-DMAP) for 4 h. Reconstructed embryos were in vitro cultured in B2 medium for 2 days. Afterwards, cleaved embryos were co-cultured with Vero cells in B2 medium supplemented with 10% FBS for 5 to 6 days up to morula/blastocyst stages. From among 88 in vitro cultured cpCOCs, 55 (62.5%) acquired meiotic nuclear and cytoplasmic maturity state after reaching the Metaphase II stage. A total of 55 enucleated oocytes underwent reconstruction and 44/55 (80.0%) were successfully fused with nuclear donor cells. Out of 44 cultured NT embryos, 21 (47.7%) were cleaved. The frequencies of cloned embryos that reached the morula and blastocyst stages were 6/44 (13.6%) and 3/44 (6.8%), respectively. In conclusion, the cell nuclei of in vitro cultured adult dermal fibroblast cells, which had undergone the contact inhibition, were able to direct the preimplantation development of equine cloned embryos to morula and blastocyst stages. This work was supported by the Scientific Net of Animal Reproduction Biotechnology.

Lipid content of non-cultured and cultured pig embryo

The objectives of the study were: (i) to work out a precise and efficient method for quantitative analysis of lipid content and (ii) to quantitatively determine the lipid content in non-cultured and cultured pig embryos. The experiment was carried out on pig embryos from zygote to late blastocyst stages produced in vivo and embryos collected at the zygote stage and then cultured in vitro up to blastocyst stage. Embryos were fixed, dehydrated, embedded in epoxy resin and cut into semi-thin sections to analyse the quantity of lipids in fat droplets. Stained sections were then analysed with Cavalieri and point counting methods to evaluate the following stereological parameters of the embryo: total embryo volume - V(e), volume density of cytoplasm per unit volume of embryo - Vv(c,e), volume density of lipid droplets per unit volume of embryo cytoplasm - Vv(fat,c) and total volume of lipid droplets per whole embryo - V(fat). Values of Vv(fat,c) and V(fat) remained unchanged up to the morula stage, but decreased significantly at blastocyst and late blastocyst stages both in cultured and non-cultured embryos. Volume density of lipid droplets per unit volume of embryo cytoplasm and total volume of lipid droplets for cultured embryos showed statistically significant differences between late blastocyst and almost all other stages. Comparisons of Vv(fat,c) in embryos at the same stages of development but differing in origin of embryos (non-cultured or cultured) show that statistically significant differences exist for all analysed stages. In conclusion, differences in lipid content observed in pig embryos were dependent on the developmental stage of the embryo as well as the culture conditions (i.e. cultured and non-cultured embryos at the same stage of development).

95 EFFICACY OF FIVE DIFFERENT SEMEN EXTENDERS FOR THE CRYOPRESERVATION OF BULL SEMEN

Replacement of animal-origin components in extenders used for bull semen freezing is of high importance for individuals involved in cattle breeding. The experiment was designed to compare efficacy of 5 different semen extenders in cryopreservation of bull semen: sodium citrate-based extender containing egg yolk (CT), commercially available Bioxcell� (IMV Technologies, L'Aigle, France), and 3 custom-made homogenized plant lipidsbased, egg yolk-free extenders (Y-1, Y-2, and Lipo) . The objective was to determine whether homogenization procedures of lipids improve the quality of the extender. Lipid homogenates of custom-made extenders were prepared in Tris buffer using a high pressure homogenizer (Nira Saovi, Parma, Italy). Ten (Y-1) or 5 (Y-2) homogenization cycles were applied and then 8% glycerol was added. Lipid liposomes were produced by simultanous high pressure homogenization of lipids and glycerol supplementation (Lipo). Semen was collected from young bulls of 3 different breeds (Simmental, Polish Red, and Holstein; 1 ejaculate/bull). Each ejaculate with at least 70% motility was split into 5 parts and processed further by a standard freezing protocol: semen was diluted at 35�C with each of the 5 extenders to a concentration of 100 � 106 spermatozoa per mL, cooled to 4�C over 5 h, aspirated into 0.25-mL plastic straws, frozen in liquid nitrogen vapor to –140�C, and then plunged into LN2. Straws were thawed in a water bath at 37�C for 20 s. Sperm motility was estimated microscopically immediately after thawing and after 5 h of storage at 22�C. Immediately after thawing, flow cytometry and SYBR-14/PI staining were used for examination of sperm membrane integrity (live/dead assay). A total of 20 000 spermatozoa of each sample were counted. Student's t-test was used to estimate statistical differences between experimental groups. The mean sperm motility after thawing ranged from 45.6% (SD = 13.7) for CT (egg yolk extender) to 57.8% (SD = 7.1) for Lipo. A significant difference (P < 0.05) was observed betweenY-1 (50.0%, SD = 9.7) and Lipo and Bioxcell (56.1%, SD = 8.6). After 5 h of storage at 22�C, the mean motility for all tested bulls ranged from 25.0% (SD = 7.1) for CT to 42.2% (SD = 7.5) for Lipo. Significant differences were observed between Lipo (P < 0.01), Y-2 (P < 0.05) and CT, and between Y-1 and Lipo (P < 0.01). Mean percentage of 'live' spermatozoa with intact membrane after freezing/thawing was 51.85% (SD = 11.49) for Y-1, 45.72% (SD = 9.36) for Y-2, 47.57% (SD = 7.93) for Lipo, 45.47% (SD = 8.35) for Bioxcell, and 49.06 (SD = 11.59) for CT. No significant differences were observed except forY-1 and Bioxcell extenders (P < 0.05). It can be concluded that both methods of lipid/glycerol homogenization can be successfully applied in the preparation of bull semen extender. In addition, extensive lipid homogenization (10 cycles) produced more transparent extender that in turn improved visualization of sperm. Custom-made plant origin lipids homogenization may provide a valuable alternative for the preparation of extenders that more closely match the membrane composition of bull sperm cells and thus contribute to development of an efficient extender free of animal-origin components for bull semen freezing.

75 EFFECT OF PHENAZINE ETHOSULFATE ON PORCINE BLASTOCYST DEVELOPMENT, APOPTOSIS, AND CRYOTOLERANCE AFTER OPEN PULLED STRAW VITRIFICATION

It is possible to improve the success of cryopreservation of in vitro-produced bovine embryos by modifying the embryos with the metabolic regulator phenazine ethosulfate (PES) (Seidel 2006 Theriogenology 65, 228–235). The PES treatment increased glucose matabolism, tended to increase the pentose phosphate pathway flux of glucose, and clearly reduced accumulation of lipids in cultured bovine embryos (De La Torre-Sanchez et al. 2006 Reprod. Fertil. Dev. 18, 597–607). It is known that porcine embryos have a considerably high content of lipids, and the success rates of their cryopreservation appear to be highly correlated with cytoplasmic lipid content. In our preliminary study, we observed that supplementation of NCSU-23 medium with PES has a positive effect on efficiency of pig blastocysts of good quality (Gajda et al.. 2007 Acta Biochim. Pol. 54(Suppl 1), 52 abst). In the present study, the effects of PES on pig blastocyst development, apoptosis, and survival after vitrification were investigated. In Exp. 1, porcine zygotes obtained from superovulated gilts were cultured in NCSU-23 medium supplemented with 0 (control), 0.025, 0.05, or 0.075 µm PES. The culture was performed at 39�C, with 5% CO2 in air, for 96–120 h. Embryo quality criteria were developmental competence (cleavage, morula stage, and blastocyst stage), cell number per blastocyst, and the degree of apoptosis as assessed by TUNEL staining. In Exp. 2, expanded blastocysts cultured with 0.025 µm PES were vitrified in a ethylene glycol and dimethyl sulfoxide mixture using open pulled straw (OPS) technology (Vajta et al. 1997 Acta Vet. Scand. 38, 349–352). After thawing, the blastocysts were cultured in vitro for re-expansion or transferred to synchronized recipients. Data were analyzed by chi-square test. There was a difference between the 0.025 µm PES-treated and the control group in percentage of cleaved embryos (99.0 and 91.4%, respectively; P < 0.05), between all experimental groups and control in percentage of morula stage (90.7, 87.8, 83.8, and 80.0%, respectively), and between 0.025 and 0.05 µm PES-treated and control in percentage of blastocyst rates (70.0, 75.5, and 65.7%, respectively). The number of cells and percentage of TUNEL-positive nuclei per blastocyst were lower in the PES-treated than in the control group. The survival rate of blastocysts after vitrification and thawing was enhanced in the presence of PES compared to that in the PES-free group (45.2 and 38.9%, respectively; P < 0.05). After transfer of 56 expanded blastocysts cultured with PES and vitrified into 3 recipients, two gilts were confirmed pregnant at 35 days of gestation. In conclusion, a higher blastocyst percentage with a low incidence of apoptosis was obtained in the presence of PES compared to control. These blastocysts also had an increased ability to survive cryopreservation.

91 A NOVEL TECHNIQUE FOR EVALUATION OF THE LIPID CONTENT IN PIG EMBRYOS

A high level of lipids, mainly triglycerides and fatty acids, present in embryo cells in the form of lipid droplets is the major factor associated with low cryopreservation of porcine embryos. Previous results demonstrated that the low tolerance of pig embryos to cryopreservation can be increased through reduction of lipid droplet contents. Therefore, in order to improve cryopreservation techniques of porcine embryos, it is fundamental to establish proper culture conditions which ultimately will enable a decrease in lipid content. Unfortunately, there are no precise and efficient methods to evaluate the lipid contents of single pig embryos. Previously used stereological analysis combined with physical serial sectioning (Romek et al. 2007 Reprod. Domest. Anim. in press) is time-consuming, and measurement of triglyceride levels based on enzymatic hydrolysis eliminates other types of lipids from the analysis. Taking the above problems into account, we have developed a new method for evaluation of total lipid content in pig embryos. It is based on visualization of lipid droplets using the specific fluorescent dye Nile red and applying confocal scanning microscopy followed by the Cavalieri method. This method enables measurement of several stereological parameters, especially the volume density of lipid droplets per unit volume of cytoplasm Vv(fat,c), which quantifies most precisely the amount of intracellular lipid. The experiment was carried out on 2- to 4-cell and 8- to 16-cell pig embryos, morulae, blastocysts, and late blastocysts cultured in vitro. Embryos were developed from in vivo-produced zygotes to appropriate stages of development in North Carolina State University (NCSU) 23 medium. For each stage, ten of the embryos were examined. Embryos were denuded and fixed with 2% glutaraldehyde and 2% formaldehyde, stained with 100 nm Nile red (Molecular Probes, Leiden, The Netherlands), and analyzed by means of a confocal microscope LSM 510 Meta (Carl Zeiss MicroImaging GmbH, G�ttingen, Germany). Serial optical sections of each individual embryo were measured by the point counting method, and then the Cavalieri method was used to estimate Vv(fat,). Vv(fat,c) values calculated for embryos at different stages of development were compared by one-way analysis of variance and Tukey's intervals. For cultured pig embryos, volume density of lipid droplets Vv(fat,c) significantly decreased during cleavage from 0.55 µm3 µm–3 at the 2- to 4-cell-embryo stage to 0.46 µm3 µm–3 at the blastocyst stage. The differences between lipid droplet volumes calculated for morulae, blastocysts, and late blastocysts were statistically significant. In conclusion, our new method is more precise, efficient, and quick in comparison to previously used ones. Moreover, we confirmed that the content of total lipids in cultured pig embryo is reduced during its development. This research was funded by the State Committee for Scientific Research (Project No. 2 P06D 003 26) and Net of Reproduction Biotechnology.

258 THE EFFECT OF A PLANT PROTEIN COMPONENT OF MEDIA USED FOR BULL SPERM SEXING ON SPERM MEMBRANE STATUS

The aim of the work was to examine the effect of modified TALP medium (TALP/Pp, Animal Pharma B.V., Hengelo, The Netherlands)—used in the sperm sexing procedure—on bull sperm membrane status. The TALP was modified by replacement of bovine serum albumin (BSA) with a mixture of several plant proteins and soya lecithin (Pp). The Pp component was prepared using a high pressure homogenization process. The TALP/Pp had the same pH and osmotic pressure as the original TALP medium (TALP/BSA). The work was divided into 2 parts: (1) Nine ejaculates collected from 2 bulls (Holstein and Polish Red) were used. Immediately after collection, each ejaculate was split into 2 parts and diluted (1:2) with TALP/BSA or TALP/Pp. The sperm membrane status was examined after 3 days of storage at 15�C. (2) Fifteen ejaculates collected from 5 bulls (Holstein, Polish Red, and Simmental) were used. Each ejaculate was split into 2 parts: the first part was diluted with TALP/BSA, stained, incubated, and sexed according to the XY Inc. bull semen sexing procedure; the second part was diluted, stained, incubated, and collected after sexing into TALP/Pp with no egg yolk addition. In both groups no red food due was used to identify and exclude the dead spermatozoa from the sorted fractions. The sperm sexing procedure was performed with an SX MoFlo high-speed sorter at a speed of 3000–4000 cells/s. After collecting about 10 million spermatozoa, both fractions, X andY, were mixed, centrifuged at 700g for 15 min to concentrate the spermatozoa (20 million mL–1), and the sperm membranes examined. For sperm membrane examination, 'live/dead' samples were stained with SYBR-14/propidium iodide fluorochromes and analyzed by flow cytometry. The data from 20 000 spermatozoa were collected for each sample. The percentage of membrane-intact ('live') spermatozoa was taken for statistical analysis. The mean percentage of live spermatozoa stored for 3 days in TALP/BSA v. TALP/Pp was 25.7% (SD = 7.48) v. 28.58% (SD = 7.04), respectively (P < 0.01). The mean percentage of live spermatozoa in samples of sexed semen was 33.57% (SD = 18.97) for TALP/BSA and 38.51% (SD = 20.22) for TALP/Pp (P < 0.01). It can be concluded that Pp should be considered as a replacement for BSA in the TALP medium used for bull sperm sexing because (1) it results in significantly higher numbers of live spermatozoa after storage and/or sexing; (2) it eliminates a possible source of transmissible diseases (such as bovine spongiform encephalopathy); and (3) it decreases the total cost of the basic media used for the bull sperm sexing procedure.

Survival of bovine fibroblasts and cumulus cells after vitrification

The aim of the experiment was to investigate the effect of vitrification on viability and the cell cycle of bovine cumulus cells and fibroblasts after culture with or without serum starvation. In all vitrified-thawed bovine somatic cells, the number of samples that reached the confluence stage was high (50 to 100%). The viability of vitrified somatic cells depended on the concentration of the cells. The viability was higher for cells vitrified at the concentration of 10 x 10(6) per ml than for cells vitrified at a concentration of 1 x 10(6) per ml (p < 0.05; for cumulus cell, and fibroblast). Time of cell starving has had no impact on their susceptibility to vitrification in case of vitrified cumulus cells. Starving time caused shifts in proportions of subsequent cell cycle phases of vitrified fibroblasts and cumulus cells. In conclusion, the bovine cumulus and fibroblast cells can be cryopreserved successfully by vitrification procedure.

330 CORRELATION BETWEEN TWO APOPTOTIC MARKERS IN FRESH BOAR SPERMATOZOA

Apoptosis is a carefully regulated process of cell death that occurs as a normal part of development. It is a well-characterized mechanism that allows eukaryotes to eliminate unneeded, senescent, or aberrant cells, but the significance of apoptosis in ejaculated animal sperm is still unresolved. In this experiment, we designed 2 methods to detect early changes in the membranes of boar spermatozoa based on the slight increase in membrane permeability (Vybrant Apoptosis Assay Kit #4; Molecular Probes, Eugene, OR, USA) and on translocation of the phospholipid phosphatidyserine (PS) from the inner to the outer leaflet of the plasma membrane (Annexin-V-FLUOS Staining Kit; Roche, Mannheim, Germany). Detection of early changes in the sperm plasma is very important when designing storage protocols. Three ejaculates from 3 boars were used in the experiment. After collection and separation of the gel, the semen was analyzed using the following assays: (1) Annexin-V-FITC/PI assay: Sperm (2 � 106) were washed and diluted in 100 �L of HEPES buffer; 6 �L of Annexin-V-FITC and 4 �L of PI were added to the sample. The tubes were incubated for 15 min at room temperature in the dark. (2) YO-PRO-1/PI assay: YO-PRO-1 stock solution (1 �L) and 1 �L of PI stock solution were added to the samples. The tubes were gently mixed and incubated for 20 min at room temperature in the dark. After the incubation period, the sperm cell suspensions were analyzed under a fluorescence microscope at 40� magnification. At least 200 spermatozoa per sample were evaluated. Using the YO-PRO-1/PI assay, we observed 3 groups of sperm: apoptotic sperm showed green fluorescence (2–8%), necrotic sperm showed red and green fluorescence (9–37%), and live sperm showed no fluorescence (58–89%). Using the Annexin V-PI assay, 4 sperm subpopulations were easily detectable: apoptotic sperm showed green fluorescence (0.5–7%), early necrotic sperm showed red and green fluorescence (10–35%), necrotic sperm showed only red fluorescence (2–6%), and live sperm showed no fluorescence (57–87%). The results were compared by a chi-squared test. Significant differences (P &lt; 0.01) in the percentage of all sperm subpopulations (apoptotic, necrotic, and live sperm) among boars and among ejaculates from the same boar were observed. We also observed a strong correlation between these 2 methods. Using the Annexin-V-FITC/PI assay, we detected more sperm subpopulations, and this method seems to be more sensitive than the YO-PRO-1/PI assay. However, these 2 methods detect changes in membrane spermatozoa but in different aspects of apoptosis, and this may also cause differences in the frequencies of apoptotic cells found by the different assays. This study was supported by the Polish Research Committee, grant no. 2 P06D 023 30.

86 CREATION OF PORCINE TRANSGENIC NUCLEAR-TRANSFERRED EMBRYOS RECONSTRUCTED WITH EGFP-EXPRESSING ADULT DERMAL FIBROBLAST CELLS ANALYZED ON APOPTOSIS

The purpose of our study was to determine the in vitro developmental competences of porcine nuclear transfer (NT) embryos reconstructed with pWAPhGH-GFPBsd transgene-nucleofected gilt ear skin-descended fibroblast cells, which had been diagnosed on apoptosis through the live-plasma membrane fluorescent tagging. Frozen–thawed fibroblast cells, which had been in vitro-cultured up to a total confluency after 2–8 passages, were used for analysis. To detect the early apoptotic changes in the fibroblast cells, single nuclear donor cell suspension was labeled with the conjugate of Annexin V and eGFP protein. The source of recipient cells were in vitro-matured oocytes. Maternal chromosomes were eliminated by a chemically assisted microsurgical technique. Fibroblast cell–ooplast couplets were simultaneously fused and activated. Reconstructed embryos were cultured in NCSU-23/BSA/FBS medium for 6–7 days. The rates of cleavage and development to morula/blastocyst stages were examined on Days 2 and 6/7, respectively. After fluorescent analysis of adult dermal fibroblast cells, it was shown that a relatively high proportion (ranging from 20 to 30%) of donor cells exhibited ultrastructural late-apoptotic or necrotic changes. In contrast, from among the morphologically normal cells, an extremely low rate (ranging from 0 to 2%) of the cells emitted the Annexin V-eGFP-derived green fluorescence, but the other ones did not emit this biochemiluminescence. This suggests that the former subpopulation of the cells was early-apoptotic, and the latter was non-apoptotic. A total of 158 enucleated oocytes were successfully fused with non-apoptotic transgenic nuclear donor cells and intended to be in vitro-cultured. Out of 158 reconstructed oocytes, 106 (67.1%) NT embryos were cleaved. The frequencies of cloned embryos that reached the morula and blastocyst stages were 48/158 (30.4%) and 21/158 (13.3%), respectively. In conclusion, the nucleofection efficiency of in vitro-cultured porcine dermal fibroblast cells as estimated by nuclear donor live-fluorescent evaluation based on the expression index of the eGFP reporter transgene was nearly 100%. Moreover, our results demonstrate that the morphological criteria commonly used for cell viability classification are a sufficient selection factor for qualitative evaluation of nuclear donor cells to somatic cell cloning. It was also found that porcine nuclear-transferred morulae and blastocysts exhibited an approximately 100% index of xenogeneic eGFP gene transcriptional activity, which revealed the live diagnostics of emission intensity for green fluorescent protein-derived biochemiluminescence. This research was supported by the State Committee for Scientific Research as a Solicited Project number PBZ-MIN-005/P04/2002/6 from year 2003 to year 2006.

142 RELATIONSHIP BETWEEN APOPTOSIS IN BOAR SEMEN AND DNA FRAGMENTATION IN PORCINE EMBRYOS

Although apoptosis in somatic cells and in spermatocytes and spermatids in vivo is well established, the presence and significance of apoptosis in ejaculated animal sperm and its correlation with developmental competence of preimplantation embryos is still unresolved. The aim of this experiment was to study the relationship between apoptosis in boar semen and DNA fragmentation in porcine embryos. Two ejaculates from the same boar were used in the experiment. Both fresh ejaculates were analyzed using Vybrant Apoptosis Assay Kit #4 (Molecular Probes, Inc., Eugene, OR, USA). Then one of them was diluted in Biosolwens plus extender, stored for 5 days at 15°C and analyzed using YO-PRO-1/PI assay, which detect changes in the membrane of boar spermatozoa, based on the slight increase of membrane permeability. Both fresh and stored semen were used for insemination, of superovulated gilts (8 per group). After 5.5 days of insemination embryos were flushed out of the uterus and DNA integrity of obtained embryos were analyzed. DNA fragmentation and caspase-3 activity were detected in embryos using kits, Roche Diagnostics (Mannheim, Germany) and PhiPhiLux G2D2 (Calbiochem, San Diego, CA, USA), respectively. For both the fresh and stored semen, 3 groups of sperm were observed under a fluorescence microscope. In the fresh semen, 3 and 2% of apoptotic sperm, 13 and 9% of necrotic sperm, 84 and 89% of live sperm in first and second ejaculated, respectively, were observed. In stored semen, 14% of apoptotic sperm, 27% of necrotic, and 59% of live sperm were noted. In total, 141 expanded blastocysts for DNA fragmentation were analyzed. The results are summarized in Table 1. In conclusion, apoptosis in fresh boar semen was lower than in stored semen and was correlated with the TUNEL nucleus index in blastocysts. The expression of caspase-3 was positively correlated with cells positive for TUNEL. Table 1. Relationship between apoptosis in boar semen and DNA fragmentation in porcine embryos This study was supported by Polish Research Committee, grant no. 2 P06D 024 30.

361 INFLUENCE OF SEXING PROCEDURE ON BULL SPERM CHROMATIN STRUCTURE

Flow cytometry is the only reliable and relatively fast method allowing separation of live X and Y spermatozoa for sex regulation. Many thousands of animals of different mammalian species have been born after insemination with sexed semen during the past 20 years. Nevertheless, the question is still open: does the bull sperm sexing technology affect chromatin structure? A case of serious chromatin damage after sexing stallion semen was reported previously (Bochenek et al. 2006 Havemeyer Foundation Monograph Series No. 18, 13 –14). The aim of this work was to examine the effect of the sexing procedure and different UV laser powers on bull sperm chromatin structure. The ejaculates of 28 bulls (one ejaculate/bull) were used in the study. Each ejaculate was divided into 5 groups: (1) control, unprocessed; (2) sorted strictly according to XY Inc. protocol (Schenk et al. 1999 Theriogenology 52, 1375 –1391); (3) as group 2, but without the Red Food dye staining used for dead spermatozoa discrimination; (4) as group 2, but with double UV laser power (300 mW); and (5) as group 3, but with double UV laser power (300 mW). Sperm sorting was performed with a MoFLoSX flow cytometer at speeds of 3000 –5000 cells/s. Sorted fractions of X and Y spermatozoa were mixed again and stored for 24 h at 15 °C. A sperm chromatin structure assay (SCSA) was performed twice on each sorted sample, immediately after sorting and after 24 h. The chromatin of control samples was examined according to the same time schedule. The percentage of spermatozoa with damaged chromatin was calculated (COMP α-t) as well as standard deviation of the α-t parameter (SD α-t). The latter parameter, although less intuitive, is considered as even more precise than COMP α-t in chromatin investigations. The mean percentage of spermatozoa with abnormal chromatin was 1.12% (SD = 0.47) for control samples. The highest level of chromatin abnormality was noted for the 300 mW group with no dead cell discrimination (Red Food staining): 1.29% (SD = 1.05). After 24 h of storage, the mean level of chromatin abnormality increased to 1.97% (SD = 0.96) in control samples whereas that in all sorted samples was lower: from 1.06% (SD = 0.4) to 1.16% (SD = 0.62) in the 150 mW/non-Red Food-stained and the 300 mW/Red Food-stained groups, respectively. This difference appeared to be statistically significant (t; P ≤ 0.05). Interestingly, the percentage of abnormal spermatozoa decreased slightly after 24 h of storage in the 300 mW/Red Food-stained and the 300 mW/non-Red Food-stained groups ( –0.13% and –0.08%, respectively). Calculation of the SD α-t parameter showed statistically significant differences in chromatin abnormality between the control group vs. the 300 mW/non-Red Food-stained group immediately after sorting and the control group vs. the 150 mW/Red Food-stained group after 24 h of storage. In conclusion, although the statistically significant increase of chromatin damage was found after sexing in some investigated groups, it seems that the level of this abnormality is far too low to affect sexed semen fertility.

151 LIPID COMPOSITION OF FAT DROPLETS OF IN VIVO- AND IN VITRO PRODUCED PORCINE EMBRYOS

Early-stage porcine embryos to peri-hatching blastocysts contain high levels of intracellular lipids in the form of fat droplets and are highly sensitive to cryopreservation. Recently, our sterological studies demonstrated that in embryos produced in vivo and cultured in vitro, the volume of lipid droplets significantly decreased from zygote to blastocyst. To date, however, there have been no reports concerning the type of lipids in pig embryos produced in vivo and in vitro. Thus, the objective of the present study was to investigate the lipid composition of fat droplets in pig embryos produced in vivo and in vitro. The experiment was carried out on pig zygotes produced in vivo and 2–4 and 8–16-cell embryos, morulae, blastocysts, and late blastocysts produced in vivo and in vitro. Embryos produced in vivo were obtained from superovulated gilts after flushing the oviduct or uterus. Embryos cultured in vitro were developed from zygotes produced in vivo. Embryos were cultured in vitro to appropiate stages of development in chemically defined medium, North Carolina State University (NCSU)-23. For analysis of the type of lipid in the fat droplets, embryos were fixed in 2.5% glutaraldehyde with the addition of 3 mM calcium chloride. The material was then embedded in Technovit 8100, cut into semi-thin sections, and analyzed by histochemical methods. Four techniques were used to detect different types of lipids: Churukian method with Oil red O, Cain method with Nile blue sulfate, Sudan black B, and osmium tetroxide methods. Fat droplets of embryos produced both in vivo and in vitro contained unsaturated hydrophobic lipids, free fatty acids, phospholipids, unsaturated esters, and triglycerides. Moreover, in the morula the total amount of lipids (especially the amount of free fatty acids and phospholipids) evidently decrease. The amount of the other unsaturated lipids decreased as early as the 2- to 4-cell stage. In conclusion, the content of different types of lipids in pig embryos is reduced during their development from zygote to blastocyst, and there are no differences in lipid composition of fat droplets between in vivo- and in vitro-produced porcine embryos. This research was funded by the State Committee for Scientific Research (Project No. 2 P06D 003 26).

Sequence analysis of proviral DNA of porcine endogenous retroviruses

Among all species analyzed, the domestic pig seems to be the most appropriate organ donor for xenotransplantation. Porcine endogenous retroviruses (PERVs) are present in genomes of all pigs and are capable of infecting human cells in vitro thus posing a serious threat for xenotransplantation procedures. Despite the abundant distribution of PERVs integrated with porcine genome, the majority of PERV proviral DNA is not capable of expressing viral proteins unless seriously mutated. The aim of the study was to analyze PERV genome for mutations. The study was performed on blood samples from 146 pigs. Long-range polymerase chain reaction (Long-PCR) was performed with primer sets designed within long terminal repeats (LTRs). Long-PCR products of different molecular weights were obtained: 530 bp (33.1% of individuals), 580 bp (76.7%), 933 bp (100%), and 2900 bp (59.8%). Amplimers of 7200 bp were absent in 12.8% of individuals, indicating the lack of intact proviral DNA. Sequence analysis showed that most PERV proviral DNA was significantly mutated, thus suggesting the inability to express functional viral RNA; however, it cannot be ruled out that compensatory recombination processes could occur enabling replication of defective proviruses.

Generation of transgenic rabbits by the novel technique of chimeric somatic cell cloning

A novel technique of chimeric somatic cell cloning was applied to produce a transgenic rabbit (NT20). Karyoplasts of transgenic adult skin fibroblasts with Tg(Wap-GH1) gene construct as a marker were microsurgically transferred into one, previously enucleated, blastomere of 2-cell non-transgenic embryos, while the second one remained intact. The reconstructed embryos either were cultured in vitro up to the blastocyst stage (Experiment I) or were transferred into recipient-females immediately after the cloning procedure (Experiment II). In Experiment I, 25/102 (24.5%) embryos formed blastocysts from whole embryos and 46/102 (44.12%) embryos developed to the blastocyst stage from single non-operated blastomeres, while the reconstructed blastomeres were damaged and degenerated. Thirteen (12.7%) embryos did not exceed 3- to 4-cell stages and 18 (17.7%) embryos were inhibited at the initial 2-cell stage. Out of 14 blastocysts which were subjected to molecular analysis, the transgene was detected in the cells of 4 blastocysts. In Experiment II, 163/217 (75.0%) embryos were transferred into 9 pseudopregnant recipient-rabbits (an average of 18 embryos per recipient). Four recipient-females (44.4%) became pregnant and delivered a total of 24 (14.7%) pups. Molecular analysis confirmed that two pups (1.2%), one live and one stillborn, showed a positive transgene signal. Live transgenic rabbit NT20 appeared healthy and anatomically as well as physiologically normal. The results of our experiments showed that transgenic adult skin fibroblast cell nuclei, which have been introduced into the cytoplasmic microenvironment of single enucleated blastomeres from 2-cell stage rabbit embryos, are able to direct the development of chimeric embryos not only to the blastocyst stage but also up to term.

Generation of cloned and chimeric embryos/offspring using the new methods of animal biotechnology

The article summarizes results of studies concerning: 1/ qualitative evaluation of pig nuclear donor cells to somatic cell cloning, 2/ developmental potency of sheep somatic cells to create chimera, 3/ efficient production of chicken chimera. The quality of nuclear donor cells is one of the most important factors to determine the efficiency of somatic cell cloning. Morphological criteria commonly used for qualitative evaluation of somatic cells may be insufficient for practical application in the cloning. Therefore, different types of somatic cells being the source of genomic DNA in the cloning procedure were analyzed on apoptosis with the use of live-DNA or plasma membrane fluorescent markers. It has been found that morphological criteria are a sufficient selection factor for qualitative evaluation of nuclear donor cells to somatic cell cloning. Developmental potencies of sheep somatic cells in embryos and chimeric animals were studied using blastocyst complementation test. Fetal fibroblasts stained with vital fluorescent dye and microsurgically placed in morulae or blastocysts were later identified in embryos cultured in vitro. Transfer of Polish merino blastocysts harbouring Heatherhead fibroblasts to recipient ewes brought about normal births at term. Newly-born animals were of merino appearance with dark patches on their noses, near the mouth and on their clovens. This overt chimerism shows that fetal fibroblasts introduced to sheep morulae/blastocysts revealed full developmental plasticity. To achieve the efficient production of chicken chimeras, the blastodermal cells from embryos of the donor breeds, (Green-legged Partridgelike breed or GPxAraucana) were transferred into the embryos of the recipient breed (White Leghorn), and the effect of chimerism on the selected reproductive and physiological traits of recipients was examined. Using the model which allowed identification of the chimerism at many loci, it has been found that 93.9% of the examined birds were chimeras. The effect of donor cells on the reproduction and physiology of the recipients was evident.

Distribution of porcine endogenous retroviruses (PERVs) DNA in organs of a domestic pig

OBJECTIVES

Domestic pig may serve as the most appropriate organ source for human xenotransplantation in the future. However, there is a serious threat of xenogeneic pathogens transmission, especially porcine endogenous retroviruses (PERVs) which are present in genomes of all pigs. The aim of this study was to monitor the prevalence and distribution of PERV DNA in organs of a domestic pig.

METHODS

We used a primer set for a highly conserved fragment of PERV gag sequence to monitor a total PERV DNA copy number and genotype-specific primer sets to study PERV subtypes distribution using Real-Time QPCR (SYBR Green I).

RESULTS

Our results showed that PERV DNA was present in all studied pigs, however, most PERV DNA molecules carried numerous mutations thus indicating inability to express functional retroviral particles. The level of PERV DNA in kidney was much higher than in heart (p = 0.007) and in the liver (p = 0.009).

CONCLUSIONS

It indicates that kidney is potentially the biggest PERV reservoir which makes it the organ of particular concern in xenotransplantation. We also conclude it is possible to monitor pig herds for individuals with the lowest PERV DNA prevalence, especially lacking PERV-C, and perhaps with only defective PERV proviruses that are unable to express functional RNA.

311 CATTLE SEX REGULATION BY SEPARATION OF X AND Y SPERMATOZOA PRELIMINARY RESULTS OF FIELD EXPERIMENT IN POLAND

The only reliable and relatively fast method of sex regulation in cattle is X and Y sperm high-speed sorting by flow cytometry. In October 2003 a field experiment started in Poland. The aim of the experiment was to examine the efficiency of sperm sexing and the fertility rate in field conditions. The semen of three Holstein bulls was used for the experiment. The semen was sexed and frozen according to modified XY, Inc. (Fort Collins, CO, USA) method. Only the X-fraction of spermatozoa was sorted and frozen. Sexing was performed at a speed of 15–20 × 106 spermatozoa/h and frozen in doses of 2.5 × 106 spermatozoa/straw. Progressive motility of spermatozoa was 90–95% immediately after sorting and 50–70% after freezeing/thawing for all three bulls. The X-fraction sorting purity was checked by re-analysis and it ranged from 90% to 96%. In total, 316 inseminations at 10 farms were performed up to June 2004. Fertility data of 178 inseminations were collected by ultrasonographic (USG) examination during the same time. Average fertility rate was 37.08%. However, significant variations of fertility rates were observed between farms: it ranged from 22.22% to 84.21%. Four calves, all females, were born after insemination with the X-fraction until June 2004. The experiment will continue.

86 CULTURE OF PIG EMBRYOS BEFORE CRYOPRESERVATION

Our previous experiment on cryoconservation of in vitro-cultured porcine embryos (Gajda and Smorag 2000 CryoLetters 21, 231–236) revealed that, unlike for other species, sensitivity to vitrification of such embryos is higher than for those obtained in vivo. Considering that, selection of an optimal in vitro culture medium for pig embryos before cryoconservation becomes more important. Two experiments have been done on 3/4-cell pig embryos. Embryos were obtained from superovulated gilts after flushing the oviduct with PBS medium supplemented with 20% fetal calf serum at 38°C. In experiment 1, the embryos were cultured in three chemically defined media: NCSU-23, NCSU-37, CZB. The culture was performed at 39°C, 5% CO2 in air for 96 to 120 h. The main evaluation criterion was development into blastocysts. Additionally, embryos that developed into blastocysts were stained with Hoechst 33342 and the cells were counted under a fluorescence microscope. Data were analyzed using chi-square and Fisher tests. The highest percentage of embryos developing into blastocysts was observed for those cultured in NCSU-23 (a): 89.2%; lower in NCSU-37 (b): 78.9%; and lowest for those in CZB medium (c): 66.6% (a,c: P < 0.05; a,b and b,c: NS). There were significantly (P < 0.001) more total cells in blastocysts obtained after culture in NCSU-23 (139.5 ± 32.8) than after culture in NCSU-37 (71.9 ± 36.6) or in CZB medium (58.3 ± 8.6). In experiment 2, embryos were cultured in vitro in NCSU-23 medium to the blastocyst stage and then vitrified (Gajda and Smorag 2002 CryoLetters 23, 385–388). Embryos were vitrified in 0.25-mL plastic straws in a mixture of 40% v/v ethylene glycol, 18% w/v Ficoll, and 0.3 M sucrose. Straws with embryos were stored in liquid nitrogen for 3 to 6 months. Dilution after rapid thawing (water bath at 20°C) was done in one step in 0.5 M sucrose solution. Eighty-five thawed blastocysts were surgically transferred into the oviducts of four synchronized recipient gilts. Two recipients became pregnant and farrowed 11 live healthy piglets. These results indicated that NCSU-23 medium provided the best conditions (of those media tested) for in vitro culture of pig embryos before vitrification. Transfer into oviducts of blastocysts that developed from in vitro-cultured and vitrified embryos resulted in full development in vivo. Research was funded by the State Committee for Scientific Research (Project No. 2 P06D 003 26).

Transgenic rabbit producing human growth hormone in milk

The gene construct WAP(6xHisThr):hGH containing the entire human growth hormone gene (hGH) under the rat whey acidic protein (WAP) promoter regulating the expression in mammary glands of mammals was prepared. The 5' end of the gene was modified by the addition of a sequence encoding six histidine residues and a sequence recognized by thrombin. The gene construct was introduced by microinjection into the male pronucleus of a fertilized oocyte. The founder male rabbit was obtained with the transgene mapping to chromosome 7. The presence of the growth hormone was confirmed in samples of milk collected during the lactation of F1 generation females. The growth hormone can be easily purified by affinity chromatography and cleavage by thrombin to an active form.

Timing of nuclear maturation of nonstored and stored domestic cat oocytes

In this study we compared the effects of preculture storage of ovaries, IVM medium, a reduced O(2) atmosphere and duration of culture on in vitro maturation (IVM) of domestic cat oocytes. One randomly selected ovary of each pair (69 pairs) was stored in PBS at 10 degrees C for 16-24h before oocyte recovery. The second ovary from each pair was used as a nonstored control. In Experiment I, we investigated the effect of culture media (TCM 199 versus SOF) and a reduced O(2) atmosphere (a humidified gas atmosphere of either 5% CO(2) in air or 5% CO(2):5% O(2):90% N(2)) on IVM of both stored and nonstored oocytes. In the second experiment, we compared timing of nuclear maturation of both stored and nonstored oocytes cultured for 17-18, 20-21, 24-26, 28-30, 33-34 or 42-45 h before being evaluated for meiotic status. In both, Experiments I and II, the recovery rate, quality and competence for maturation of oocytes originating from stored ovaries did not differ (P>0.05) compared with nonstored. In Experiment I, neither culture medium (37.5 versus 43.2% of Metaphase II, respectively in TCM 199 versus SOF) or gas atmosphere (40.0 versus 32.5% of Metaphase II, respectively in 5% CO(2) in air versus 5% CO(2):5% O(2):90% N(2)) affected oocyte maturation. In Experiment II, the mean proportion of oocytes achieving Metaphase II within 17-18 h of culture was 36.1% and did not significantly increase (P>0.05) over time up to 28 h. The highest proportion of oocytes (67.3%) reached Metaphase II stage after 42-45 h of culture. Therefore, we conclude that two "waves" of nuclear maturation of cat oocytes can be distinguished. The first wave takes place within 26 h and it is likely that most oocytes of this wave mature by 17-18 h; the second wave occurs after 28-30 h of IVM. It can be assumed that this double wave may reflect the presence of two oocyte populations with two different degrees of "prematuration" which require different lengths of IVM.

Effect of antioxidants added to boar semen extender on the semen survival time and sperm chromatin structure

The aim of the experiment was to determine the effect of potential antioxidants (adenosine, L-cysteine hydrochloride, ascorbic acid, magnesium fumarate and prolactin) supplementing the Biosolwens extender on semen survival time and sperm chromatin structure. The semen motility was examined every day and the susceptibility of sperm chromatin to denaturation was evaluated on collection day and day 15 of storage. The addition of magnesium fumarate to Biosolwens extender increased sperm survival but resulted in the highest increment in the proportion of sperm with damaged chromatin. Biosolwens supplemented with 200 mg of L-cysteine hydrochloride brought the best results. It is possible that lower concentrations of this component would act in a more protective manner. The examination of the chromatin structure appears to be an useful tool for investigation of semen preservation.

Flow cytometric cell cycle analysis of somatic cells primary cultures established for bovine cloning

An important factor governing developmental rates of somatic cloned embryos is the phase of the cell cycle of donor nuclei. The aim of this experiment was to investigate the distribution of cell cycle phases in bovine cumulus and fibroblast cells cultured using routine treatment, and under cell cycle-arresting treatments. The highest percentages of cumulus cells in the G0 + G1 stage were observed in uncultured, frozen/thawed cells originating from immature oocytes (79.8 +/- 2.2%), fresh and frozen/thawed cells from in vitro matured oocytes (84.1 +/- 6.2 and 77.8 +/- 5.7%, respectively), and in cycling cells (72.7 +/- 16.3 and 78.4 +/- 11.2%, respectively for cumulus cells from immature and in vitro matured oocytes). Serum starvation of cumulus cultures markedly decreased percentages of cells in G0 + G1, and prolonged starvation significantly increased (P < 0.05) percentages of cells in G2 + M phase. Culture of cumulus cells to confluency did not increase percentages of cells in G0 + G1. Contrary to findings in cumulus cells, significantly higher percentages of cells in G0 + G1 were apparent when fibroblast cells were cultured to confluency or serum starved, and significantly increased (P < 0.01) as the starvation period was prolonged. It is concluded that for particular cell types specific strategies should be used to attain improvements in the efficiency of cloning procedures.

In vitro developmental competence of domestic cat embryos after somatic cloning: a preliminary report

This work was undertaken in order to study the developmental competence of nuclear transfer feline embryos with regard to the recipient-cytoplast's age and type of somatic cells used as donor nuclei. Oocytes were recovered by mincing the ovaries in HEPES-buffered TCM-199. Selected cumulus-oocyte complexes (COCs) with compact cumulus cell mass and a dark, homogenous ooplasm were cultured for maturation in the modified medium TC-199 for 24, 35, and 43 h, and after enucleation were used as a source of recipient cytoplasts for exogenous somatic nuclei. Two experiments were carried out. In Experiment 1, the source of recipient cytoplasts was oocytes matured in vitro for 24 h (Group 1), 35 h (Group 2), and 43 h (Group 3), while the source of donor nuclei was cycling fetal fibroblasts. Somatic cell-cytoplast complexes (SC-CCs) were fused electrically by double DC pulses of 2.0 kV/cm for 15 micros. The reconstructed embryos were cultured in B2 medium for 72 h after NT, then co-cultured with BRL cells in the same medium supplemented with 10% FBS at 38.5 degrees C under 5% CO2 in air. In Groups 1, 2, and 3, the fusion rates were 71.4 (25/35), 74.6 (47/63), and 57.5% (46/80), respectively. The cleavage rates in Groups 1, 2, and 3 were 80.0 (20/25), 55.3 (26/47), and 60.8% (28/46), respectively. The development to morula and blastocyst stages was higher in Groups 1 and 2 compared to Group 3 (morula stage 14/25 (56.0%), 16/47 (34.0%), and 13/46 (28.2%); blastocyst stage 2/20 (8.0%), 4/47, (8.5%), and 0/46, respectively). In Experiment 2, the oocytes matured for 24-35 h were used as a source of recipient cytoplasts and cycling fetal fibroblasts and cumulus cells derived from mature COCs were used as a source of donor nuclei. The fusion rates were 115/193 (59.6%) versus 65/143 (45.4%) for fetal fibroblasts and cumulus cells, respectively. The cleavage rate was 72/115 (62.6%) versus 48/65 (73.8%), and the development to blastocyst stage 6/115 (5.2%) versus 5/65 (7.7%), for fetal fibroblast and cumulus cells, respectively. In conclusion, a prolonged maturation period of cat oocytes decreases developmental competence of reconstructed embryos, especially the ability to reach the blastocyst stage. The in vitro development of reconstructed embryos with either nuclei of fetal fibroblasts or cumulus cells was at approximately the same level.

[On the problem of human cloning]

Somatic cell cloning technique in mammals is still not very efficient, but intensive efforts have been made to improve it. Considering the great biological affinity of humans and animals, the cloning technique can in the not too distant future be applied in human cloning and improved to the point of becoming safe. Even when we make such an assumption, I consider it irrational and dangerous to clone the human in order to make their copies (with human cloning for therapeutic purposes being another problem). Life, which is generated by the union of egg cell and spermatozoon is an unforeseeable combination of genetic possibilities, but at the same time it offers a unique chance for the human being, both as an individual and a species. The creation of life by genetic duplication of an already formed individual means a great reduction not only in the biological sense. Action like this is evidence of extreme egocentrism and totalitarian thinking, and its proponents should first answer the question whether they would consider cloning themselves. An answer in the affirmative would help to establish the underlying reasons for their approval.

Effect of rabbit age on sperm chromatin structure

The aim of this study was to determine the relationship between the age of male rabbits and the sperm chromatin structure. The studies involved the semen of New Zealand White rabbits between 5 and 28 months of age. A flow cytometry and sperm chromatin structure assay (SCSA) method was used to determine chromatin structure. The results of cytometric chromatin structure assay suggested a relatively high stability of sperm chromatin in the rabbit. Between 6 and 16 months of age, the mean percentage of sperm with damaged chromatin was the lowest and ranged from 1.7 to 2.4%. Decreased sperm chromatin stability was found in ejaculates taken from male rabbits less than 5 months and more than 20 months of age.

Sperm chromatin structure assay of bulls qualified for artificial insemination

The goal of our study was to find the relationship between fertility of bulls qualified for AI and the percentage of spermatozoa with abnormal chromatin structure as an independent parameter. We used the frozen semen of 8 mature bulls from one AI center. Each bull was represented by 3 ejaculates collected with at least 2-week intervals. Bull fertility was calculated on the basis of non-return ratio and was expressed as a scale where 100 points represented the average fertility of all the AI center's bulls. Bulls with lower or higher fertility received a lower or higher score respectively. Fertility scores of bulls used in the study ranged from 83 to 104 . Semen was processed according to the SCSA (sperm chromatin structure assay) method and was analyzed by flow cytometry. "Artificial" alpha(t) (alpha(t)=red/green+red fluorescence) and red fluorescence histograms were used for calculation of COMPalpha(t), SDalpha(t), %Red, %PeakR and MeanR parameters. The percentage of spermatozoa with abnormal chromatin ranged from 1.2% to 23.8%. A large variation among ejaculates was found for bulls with lower fertility. Fertility correlated significantly with COMPalpha(t) (-0.50, P < 0.05), SDalpha(t) (-0.55, P < 0.01), %Red (-0.53, P < 0.01), %PeakR (-0.58, P < 0.01) and MeanR (-0.45, P < 0.05). The SCSA method has a practical application in analyzing spermatogenesis disorders in bulls. If regularly applied, it allows us to identify and eliminate ejaculates with a high level of sperm chromatin abnormalities.

Sperm chromatin integrity of bucks transgenic for the WAP bGH gene

The aim of the study was to compare sperm chromatin structure of transgenic and non-transgenic rabbits. In addition, the effect of chromatin structure on semen fertility was determined. Twenty male rabbits transgenic (TG) for WAP bGH gene (Edison Biotechnology Institute Ohio University, USA) and nine non-transgenic (NTG) males were used. Both TG and NTG rabbits were 13-18 months old. Semen was collected at 1-week intervals and 3-7 ejaculates from each rabbit were examined in total. Sperm chromatin abnormalities were measured flow cytometrically according to the Sperm Chromatin Structure Assay method: after chromatin denaturation by low pH, sperm cells were stained with metachromatic fluorochrome acridine orange. Spermatozoa with abnormal chromatin structure and, subsequently, higher degree of denaturation, showed a shift in red fluorescence. Two different methods of semen fertility estimation were used: (1) for TG rabbits, AI of superovulated does and calculation of percentages of fertilised eggs and embryos developing in vitro to the blastocyst stage; (2) for NTG rabbits, AI of non-stimulated does and calculation of percentages of pregnant does and mean litter sizes. The mean value of COMPalpha(t) was 3.71 for TG rabbits and 2.89 for NTG rabbits (no significant difference, t-test). The mean values of S.D.alpha(t) for the TG and NTG rabbits were 10.94 and 10.40 (no significant difference, t-test), respectively. There were no significant correlations between sperm chromatin structure of TG males and the percentages of fertilised eggs or embryos developing to the blastocyst stage. A statistically significant correlation (-0.68, P<0.05) was found between S.D.alpha(t) of NTG males and percentages of pregnant does. The results showed chromatin stability was not different for sperm obtained from TG versus NTG bucks. The presence of WAP bGH gene construct in the genome of transgenic rabbits did not cause any spermatogenesis process disturbances leading to the production of spermatozoa with damaged chromatin structure. This suggests that the mere presence of the introduced gene construct does not lead to any abnormalities in DNA and chromatin proteins interaction. The possible chromatin damages in transgenic animals should be attributed to the activity of the introduced gene. The relationships between chromatin structure and fertility are only significant for sperm from NTG bucks.

Survival of pig morula and blastocyst after exposure to vitrification media or vitrification

The aim of this experiment was to examine the survival of porcine embryos following exposure to vitrification solutions and vitrification. The work was carried out on non-cultured and cultured morulae and blastocysts. The viability of treated embryos was assessed by their ability to develop in in vitro culture. The results showed that the most detrimental step in the vitrification of pig embryos is exposing them specifically to a vitrification medium rather than the vitrification process itself. Moreover, we demonstrated the beneficial effect of culture on the viability of pig embryos after vitrification

Demi-embryo production from hatching of zona-drilled bovine and rabbit blastocysts

It is known that the pregnancy rate resulting after transfer of bisected embryos is lower than after transfer of whole embryos. The main reason is the reduced cell number in the demi-embryo which is less than 1 2 of that in the intact embryo, since a number of blastomeres is damaged as a result of the procedure used in conventional embryo splitting. The aim of our experiment was to develop a non-invasive procedure which would limit cell losses during microsurgery. The experiment was carried out on bovine IVM-IVF embryos at middle, late and expanded blastocyst stage and rabbit embryos at late blastocyst stage cultured in vitro from in vivo produced zygotes. The zona pellucida of these embryos was drilled on the line between the inner cell mass and the trophoblast using a glass microneedle (</= 2 microm) or micropipette (</= 30 microm). The procedure resulted in expulsion of the blastocyst through the perforation and formation of an incomplete demi-embryo configuration, connected by a very thin cell bridge (figure eight in shape). To separate the parts of the embryo, the cell bridge was cut using a glass microneedle. During the separation only a few cells were damaged. As a result of the procedure 4 20 (20.0%), 48 144 (33.3%) and 3 40 (7.5%) middle, late and expanded blastocysts hatched according to the pattern described. The developed procedure could be considered as a non-invasive alternative to conventional embryo splitting.

The effect of co-culture system on developmental capacity of bovine IVM/IVF oocytes

Two experiments were conducted to compare the influence of different culture systems and the oviduct donor's cycle phase on the developmental potential of co-cultured bovine embryos derived from IVM/IVF oocytes and to establish an efficient freezing method for oviduct epithelial cells. In the first experiment, the effects of media (Menezo B2, synthetic oviduct fluid SOF); sera (no serum, fetal calf serum FCS, human serum HS); and the presence or absence of monolayer of bovine oviduct epithelial cells (BOEC) on developmental capacity of bovine embryos were investigated. In the second experiment, the influence of oviduct donor's hormonal status (superovulated versus unstimulated) and the cryopreservation of oviductal tissue on the support of developmental competence of bovine IVM/IVF-derived zygotes were examined. Oviduct epithelial cells were cryopreserved according to the modified two-step method previously applied to rabbit embryos. For zygotes co-cultured with a monolayer of BOEC the following blastocyst development rates were obtained: 40.1% (63/157); 34.5% (60/174); 13.0% (7/54); and 19.2% (14/73), respectively, in B2 serum-free medium, B2 plus 20% HS, SOF plus 20% HS, and SOF plus 20% FCS medium. In the absence of BOEC the rates were 12.3% (10/81); 41.4% (36/87); and 8.9% (6/67), respectively, in B2 plus 20% HS, SOF plus 20% HS, and SOF plus 20% FCS. It was shown that the source of oviduct epithelial cells and previous freezing had no influence on the proportion of cleaved zygotes (approximately 70%) or on the percentage of blastocysts (approximately 20%).

Cryopreservation of mammalian ova and embryos by vitrification

Vitrification is a new approach to oocyte and embryo cryoconservation. It consists in the solidification of a solution caused not by crystallization, but by a drastic increase in viscosity during cooling. The application of this approach to cryoconservation of oocytes and embryos of different species depends upon the development of proper procedures and non-toxic media. From the technical point of view, the vitrification method is simple and relatively easily applicable under field conditions. The authors review the current procedures applied to oocytes and embryos of laboratory and farm animals.

In vitro and in vivo development of bovine embryos from zygotes and 2-cell embryos microinjected with exogenous DNA

The objectives of these experiments were: 1) to determine an effective culture method for production of transferable bovine embryos following exogenous DNA microinjection; 2) to determine the effect of these methods on the ability of the injected zygotes and 2-cell embryos to develop in vivo; and, 3) to compare development of embryos microinjected as zygotes or 2-cell embryos. DNA fragments encoding bovine growth hormone (bGH), bGH-10Delta6, and a bGH antagonist, bGH-M8 (5) were used. A total of 639 zygotes and 153 2-cell embryos were injected. Zygotes and 2-cell embryos microinjected with bGH-M8 were incubated for 6 days in oviducts of intermediate recipients (rabbits or sheep) or co-cultured in vitro with bovine oviduct epithelial cells. Zygotes and 2-cell embryos microinjected with bGH-10Delta6 were co-cultured in vitro only. The most effective method for the production of transferable bovine embryos following exogenous DNA microinjection was via in vitro co-culturing with bovine epithelial cells. For example, 32.3% of the bGH-M8 and 33.5% of the bGH-10Delta6 microinjected zygotes reached the morula/blastocyst stage while 48.4% and 63.0% of the 2-cell embryos injected with bGH-M8 and bGH-10Delta6, respectively, developed to the morula/blastocyst stage. The percentage of blastocysts obtained for control, non-injected zygotes and 2-cell embryos was 34.5% and 69.6%, respectively. The developmental rate to the morula/blastocyst stage was approximately 20% greater for embryos obtained from microinjected 2-cell embryos relative to microinjected zygotes. However, there was no significant difference in pregnancy rates following transfer of these blastocysts to cow uteri.

The effective culture method of zona-free rabbit 1-, 2- and 4-cell embryos

The effect of modified incubation systems on the development capacity of the zona-free rabbit embryos was examined. Embryos at 1-, 2- and 4-cell stages were used. The removal of the zona pellucida was accomplished by the enzymic-mechanical technique. Denuded rabbit embryos were cultured using 3 incubation systems. In the first and the second system the embryos were cultured in microdrops. The difference between these first 2 systems concerned the volume of the microdrops and the kind of paraffin oil used. In the first system the embryos were cultured in 5mul microdrops covered with light or heavy paraffin oil; in the second system embryos were cultured in 40-mul microdrops under light paraffin oil. The third traditional system involved the incubation of embryos in glass capillaries into separated columns of medium. The percentage of blastocysts obtained from 1-cell embryos cultured in the first incubation system was 6.1% with heavy paraffin oil as the covering layer and 29.0% with light paraffin oil. In the second and third incubation systems blastocyst yield was 30.8 and 59.6%, respectively. The percentage of blastocysts obtained from 2-cell and 4-cell stage embryos with heavy paraffin oil was 18.7 and 25.0%, respectively; with light paraffin oil these figures were 40.0 and 50.0%, respectively. In the second incubation system these figures were 49.3 and 72.3%; and in the third incubation system they were 72.9 and 78.3%, respectively. The results of the experiment showed that culture into glass capillaries is undoubtedly an effecient method of culturing of the zona-free rabbit embryos.

Factors affecting the survival of one- and two-cell rabbit embryos cryopreserved by vitrification

The effects of equilibration time, glycerol (GLY), and 1,2-propanediol (PROH) concentration, and of vitrification and sucrose solution on the viability of 1- and 2-cell rabbit embryos were investigated. After collection, the embryos were equilibrated for 5 or 10 minutes in phosphate buffered saline (PBS) containing 10% GLY-20% PROH and were exposed for 30 seconds at 4 degrees C or were exposed and vitrified in one of two vitrification solutions 35% GLY-35% PROH or 20% GLY-50% PROH. The in vitro survival rates of 1-cell embryos equilibrated for both 5 and 10 minutes were lower (34.0 and 48.0%, respectively) than those of 2-cell embryos (78.8 and 68.5%, respectively; P<0.01). No differences were noted in the viability of embryos exposed to the 2 vitrification solutions. Following vitrification in a mixture of 35% GLY-35% PROH, the survival rates of 1- and 2-cell embryos were 18.3 and 13.7% and 19.6 and 10.4% for 5 and 10 minutes of equilibration, respectively. The survival rates of 1- and 2-cell embryos vitrified in a solution of 20% GLY-50% PROH were 25.7 and 35.4% and 26.2 and 21.3% for 5 and 10 minutes of equilibration, respectively. The survival rates of 1-and 2-cell embryos stored in 1M sucrose solution were 63.8 and 84.0%, respectively. In conclusion, the viability of vitrified 1- and 2-cell rabbit embryos was reduced as a consequence of their equilibration before vitrification, the exposure to vitrification solution and the dilution in a sucrose solution rather than of the vitrification process itself.