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It was previously demonstrated that the kinetics of early cleavage could be used to discriminate between bovine bulls with high and low field fertility (Ward F et al.2001 Mol. Reprod. Dev. 60, 47–55). Marked differences exist in the kinetics of sperm penetration between bulls, and this may be a useful predictor of field fertility in cattle (Ward F et al.2002 Theriogenology 57, 2105–2117). It is well known that the ability to fertilize oocytes in vitroand to sustain embryo development varies significantly among buffalo bulls. Therefore, the aim of this work was to evaluate whether the speed of oocyte penetration after IVF was correlated with the blastocyst rates obtainable with different bulls in buffalo species. In Experiment 1, in vitro-matured buffalo oocytes were co-incubated with MitoTracker-labeled spermatozoa (Ward F et al.2002 Theriogenology 57, 2105–2117) from 6 different bulls, over 2 replicates. Oocytes were subsequently fixed every 3 h (up to 18 h) postinsemination (pi). At each time point, oocytes were denuded, dezoned, fixed in ethanol overnight, and stained with 4′,6-diamidino-2-phenylindole for nuclei examination under a fluorescence microscope. In Experiment 2, in vitro-matured oocytes were fertilized with sperm from the same 6 bulls and were cultured to the blastocyst stage, over 4 replicates. Bulls were tested, collectively, on each batch of ovaries in both experiments. Differences in the percentages of monospermic penetration among bulls were analyzed by chi-square test. Correlation and multiple regression analyses were also carried out between the speed of penetration and blastocyst yields. Marked differences in the kinetics of sperm penetration were found among buffalo bulls, as shown in Table 1. Interestingly, a correlation was found between the blastocyst rate and the percentage of oocytes penetrated at 6 h (r = 0.71; P< 0.01), at 9 h (r = 0.65; P< 0.05), at 12 h (r = 0.77; P< 0.01), and at 18 h pi (r = 0.59; P< 0.05). Regression analysis showed that the optimal time of penetration for predicting the blastocyst rate was 12 h pi (R2= 0.6). In conclusion, the kinetics of sperm penetration may be a useful marker to predict the in vitro-fertilizing ability of buffalo bulls. The great variability in the speed of oocyte penetration suggests inserting this assessment in the preliminary screening of bulls before their utilization in IVF programs. This may be helpful in selecting high-fertility bulls and identifying the optimal gamete co-incubation times for each bull used.Table 1.Percentage of oocytes penetrated at each time point (hpi, h postinsemination) by different bulls1 [ABSTRACT FROM AUTHOR]

It was previously reported that osteopontin (OPN), an acidic single-chain phosphorylated glycoprotein found in the oviductal fluid in cattle (Gabler C et al.2003 Reproduction 126, 721–729), is able to facilitate fertilization in this species (Gasparrini B et al.2008 Reprod. Fertil. Dev. 20(Suppl. I), 180 abst). The present study aimed to investigate whether the addition of OPN to the fertilization medium would affect both cleavage and postfertilization embryo development in the buffalo. To assess the influence of OPN on cleavage and blastocyst rates, in vitro-matured oocytes were fertilized in modified Tyrode''s albumin lactate pyruvate medium (Lu KH et al.1987 Vet. Rec. 121, 259–260) supplemented with penicillamine, hypotaurine, and heparin, in the presence of 0.0 (n= 258), 0.1 (n= 263), 1 (n= 261), and 10 μg mL-1(n= 264) of OPN. In vitrofertilization was carried out with frozen–thawed spermatozoa from a bull already tested for IVF. After 20 to 22 h of co-incubation at 38.5°C and 5% CO2in air, putative zygotes were gently pipetted to remove cumulus cells, washed, and transferred, 10 per droplet, into 20 μL of SOF medium including essential and nonessential amino acids and BSA (Tervit HR et al.1972 J. Reprod. Fertil. 30(3), 493–497), in a controlled gas atmosphere consisting of 5% CO2, 7% O2, and 88% N2, in humidified air, at 38.5°C. The culture medium was changed on Day 5 (Day 0 = day of insemination), when cleavage rate was assessed and embryos were moved into fresh medium for an additional 2 days. On Day 7, development rates into blastocysts of superior quality were recorded. Differences in the percentages of both cleavage and blastocyst rates among groups were analyzed by chi-square test. Significantly higher cleavage rates (59.3, 70.3, 71.6, and 42.4%, respectively, in the control group and in the groups with 0.1, 1, and 10 μg mL-1of OPN; P< 0.01) were observed in the groups with 0.1 and 1 μg mL-1of OPN compared with the other groups. Likewise, higher blastocyst rate percentages (17.4, 27.4, 29.9, and 9.5%, respectively, in the control group and in the groups with 0.1, 1, and 10 μg mL-1of OPN; P< 0.01) were observed in the groups with 0.1 and 1 μg mL-1of OPN compared with the other groups. In conclusion, these results showed that addition of low concentrations of OPN in the fertilization medium improved both cleavage and postfertilization embryo development in the buffalo, whereas the higher concentration resulted in impaired late-stage embryo development. [ABSTRACT FROM AUTHOR]

The overall in vitro embryo production efficiency in buffalo is hampered by the poor fertilization rate. It is known that the quality of the frozen semen may affect fertilization efficiency. However, it is not possible to rule out that the process of capacitation, required by spermatozoa to acquire the fertilizing ability, is impaired in the in vitro fertilization (IVF) system. Although several agents have been proven to induce sperm capacitation in vitro, heparin treatment is still the most efficient method in most of the domestic species. There is evidence that capacitation is part of an oxidative process and that nitric oxide (NO) acts as a capacitation inducer in human (Herrero et al. 1999 Biol. Reprod. 61, 575–581) and bovine (Rodriguez et al. 2005 Anim. Reprod. Sci. 85, 231–242) spermatozoa. The aim of the present study was to evaluate whether sodium nitroprusside (SNP), a well-known generator of NO in vitro, improves buffalo sperm capacitation in vitro. Frozen–thawed sperm from a bull previously tested for IVF were treated by swim-up in order to select only the motile population. Spermatozoa were incubated in the presence of 0.01 mM heparin (control group) for 1 h (n = 266), 2 h (n = 270), and 3 h (n = 306), and in the presence of 10 M SNP for 1 h (n = 302), 2 h (n = 286), and 3 h (n = 260). The concentration of SNP was chosen on the basis of a preliminary dose-response trial (0.1 M, 1 M, and 10 M). Following incubation with these agents, sperm were exposed for 15 min to 60 g mL-1 of lysophosphatidylcholine, an agent known to induce acrosome reaction only on capacitated spermatozoa. Trypan blue was used first to differentiate live from dead spermatozoa and the dried smears were then fixed in 37% formaldehyde and stained with Giemsa for acrosome evaluation by microscopic examination. The proportion of acrosome-reacted spermatozoa in each group was used to assess the efficiency of capacitation under different incubation conditions. Differences between groups were analyzed by chi-squared test. No dead spermatozoa were found in all groups. Following 1-h sperm treatment with either heparin or SNP, the proportion of acrosome-reacted spermatozoa was similar (35.3% vs. 28.5%, respectively). However, extending the incubation time to 2 h, SNP significantly (P < 0.01) increased the incidence of acrosome reaction compared to heparin (60.1% vs. 44.1%, respectively). Analogously, when the sperm treatment was prolonged to 3 h, SNP gave a significantly (P < 0.01) higher percentage of acrosome reaction compared to the control (68.8% vs. 36.6%, respectively). In conclusion, sperm treatment with SNP for either 2 or 3 h significant improved the efficiency of buffalo sperm capacitation in vitro compared with heparin, that is, the capacitating agent currently used in the IVF system. The promoting effect of SNP indirectly indicates that NO acts as a capacitation inducer in buffalo spermatozoa. Finally, these results suggest the need to evaluate the effect of SNP on the fertilizing capability of buffalo spermatozoa in vitro. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the efficiency of different combinations of cryoprotectants for vitrification of IVP buffalo (Bubalus bubalis) embryos by the cryotop method (Kuwayama et al. 2005 RBM Online 11, 300–308). In group A, we evaluated the vitrification and warming solutions previously used to vitrify buffalo embryos in French straws (Gasparrini et al. 2001 Theriogenology 55, 307). Embryos were equilibrated in 1.4 M glycerol for 5 min and in 1.4 M glycerol and 3.6 M ethylene glycol (EG) for an additional 5 min. After being transferred into 3.4 M glycerol and 4.6 M EG for 25 s, individual embryos were picked up in an extremely small volume (<0.1 L) of vitrification solution and placed on the top of a very fine polypropylene strip (0.4 mm wide 20 mm long 0.1 mm thick) attached to a hard plastic handle, kindly provided by M. Kuwayama. Each embryo was placed onto the thin strip of the Cryotop and immediately submerged into liquid nitrogen. For warming, the strip of the Cryotop was immersed directly into a 0.5 M sucrose solution; embryos were retrieved and transferred into 0.25 M sucrose for 5 min before culture in SOF medium. In group B, we examined the vitrification and warming solutions previously used for OPS vitrification of buffalo embryos (De Rosa et al. 2006 Reprod. Fertil. Dev. 18, 153). Embryos were equilibrated in 7.5% EG + 7.5% dimethyl sulfoxide (DMSO) for 3 min before transfer into 16.5% EG + 16.5% DMSO + 0.5 M sucrose. After 25 s, they were placed on the cryotop, as previously described, and submerged into liquid nitrogen. For warming, embryos were recovered into a 0.25 M sucrose solution for 1 min, transferred into 0.15 M sucrose for 5 min, and cultured in SOF. IVP buffalo embryos of excellent quality that, by Day 7 of culture (Day 0 = in vitro fertilization), had reached the blastocyst stage (n = 44 and 53 for groups A and B, respectively), over 6 replicates, were vitrified. Embryo survival rate was determined as the percentage of vitrified-warmed embryos undergoing further development during a 24-h in vitro culture period. Differences between methods were analyzed by chi-square test. A significantly higher embryo survival rate was recorded in Group B compared to Group A (67.9 vs. 43.2% respectively; P < 0.05). In conclusion, it was demonstrated that cryotop vitrification, with the combination of cryoprotectants used in group B, is a valid tool to cryopreserve IVP buffalo blastocysts. [ABSTRACT FROM AUTHOR]

Despite the increasing interest, buffalo oocyte cryopreservation is still inefficient, especially in terms of blastocyst development after IVF. The aim of this work was to evaluate chromatin and spindle organization of buffalo in vitro-matured oocytes after vitrification/warming by cryotop and after their simple exposure to cryoprotectants (CP). An overall amount of 251 COC was selected and matured in vitro. In the vitrification group, COC were first exposed to 10% ethylene glycol (EG) + 10% DMSO for 3 min, and then to 20% EG + 20% of DMSO and 0.5 msucrose, loaded on cryotops, and plunged into liquid nitrogen within 25 s. Oocytes were warmed into a 1.25 msucrose solution for 1 min and then to decreasing concentrations of sucrose (0.625 m, 0.42 m, and 0.31 m) for 30s each. In order to test CP toxicity, COC were simply exposed to the vitrification and warming solutions. Two hours after warming, oocytes were fixed and immunostained for microtubules using a method previously described (Messinger SM and Albertini DF 1991 J. Cell Sci. 100, 289–298), stained for nuclei with Hoechst, and examined by fluorescence microscopy. Fresh in vitro-matured oocytes were fixed and stained as controls. Data were analyzed by chi-square test; results are shown in Table 1. The percentages of MII oocytes in the control and vitrification groups were greater than in the toxicity group, in which a greater percentage of telophase II stage oocytes were found compared with both the control and vitrification groups, indicating occurrence of activation. Of the MII oocytes, both exposure to CP and vitrification procedures gave greater percentages of oocytes with abnormal spindle and abnormal chromatin configuration compared with the control. An unexpected datum was the evidence of a significant percentage of spontaneously activated oocytes in the toxicity group. We speculate that the lack of activation in the vitrification group may be related to the slowing down of metabolic activity subsequent to thermal shock, and hence, that activation after vitrification may occur later than 2 h post-warming. In conclusion, the simple exposure to CP causes activation of the COC and damage to the cytoskeleton similar to that induced by the whole vitrification protocol. The damages to the meiotic spindle and DNA fragmentation may lead to aneuploidy incompatible with subsequent embryo development and account for the poor embryo development currently recorded in buffalo.Table 1.Chromatin and spindle organization in oocytes vitrified and exposed to cryoprotectants [ABSTRACT FROM AUTHOR]

The establishment of porcine pluripotent ES cell lines would be an exciting and novel tool for animal biotechnology, such as cloning and transgenesis. Furthermore, it would represent a useful model for biomedical research, cell therapy, xenotransplantation as well as developmental biology research. However, in spite of several studies, no conclusive results have been obtained and a number of technical questions are still to be answered in order to derive genuine ES cells in the pig. Here we report the results obtained in our laboratory aimed at comparing IVF v. parthenogenetic embryos as a source for the establishment of putative ES cells. Oocytes were divided in two groups and subjected to IVF or parthenogenetically activated with ionomicyn and 6-DMAP. They were cultured in NCSU for 7 days and then subjected to immuno-surgery. Inner cell mass were plated onto inactivated STO feeder cells and outgrowth formation was monitored. Cells were passaged to a new STO monolayer every 7 days. Assessment of pluripotency markers was carried out both by RT-PCR and immunocytochemical analysis at every passage for up to 22 passages. Telomerase activity was measured every 5 passages. The results indicate that parthenogenetic embryos, although less resilient than IVF embryos to immuno-surgery, have a significantly greater ability to generate outgrowths and stable cell lines. Moreover, 77% of the 39 parthenogenetic lines derived v. only 33% of the IVF ones expressed pluripotency markers and displayed high telomerase activity. Altogether our findings are consistent with data obtained in the human where the efficiency to derive hES cell lines from parthenogenetic blastocysts appears greater as compared with regular blastocysts from IVF embryos (Cheng L 2008 Cell Research 18, 215–217).Table 1.Supported by: Prin 2005, 2006. [ABSTRACT FROM AUTHOR]

Osteopontin (OPN) is an acidic single-chain phosphorylated glycoprotein found both in the oviduct fluid (ODF) and oviductal epithelium in cattle, which is believed to facilitate fertilization. It was recently reported that addition of a rabbit polyclonal immunoglobulin G antibody against purified bovine milk OPN with sperm oocytes, bovine oocytes, or both decreased (P < 0.05) fertilization compared with the in vitro-fertilized control (Goncalves et al. 2007 Theriogenology 67, 468–74). The aim of the present work was to determine the effect of in vitro addition of OPN to the fertilization medium on both cleavage and postfertilization embryo development in cattle. In the first experiment, in vitro-matured oocytes were fertilized in modified TALP medium in the presence of 0.0, 0.1, 1.0, or 10 µg mL–1 of OPN. In a second experiment, matured oocytes were in vitro-fertilized in modified TALP medium in the presence of 0.0, 10, 20, or 40 µg mL–1 of OPN. In vitro fertilization was carried out with frozen–thawed spermatozoa from a bull previously tested for IVF. After 20 to 22 h of coincubation at 39C, 5% in CO2 in air, presumptive zygotes were vortexed to remove cumulus cells, washed, and transferred, 30 to 50 per well, into 400 µL of SOF modified medium. Zygotes were incubated in a humidified mixture of 5% CO2, 7% O2, and 88% N2 in air at a temperature of 39C. On Day 7 of development (Day 0 = day of insemination), cleavage and development rates into transferable embryos (TE)–tight morulae (TM) and blastocysts (Bl) of superior quality were recorded. Differences in the percentages of both cleavage and blastocyst rates among groups were analyzed by a chi-square test. In experiment 1, numerically higher percentages of TM–Bl (29.5, 29.5, 30.5, and 37.5%, respectively, in the control group and in the groups with 0.1, 1, and 10 µg mL–1 of OPN; P = 0.25) and Bl (28.6, 27.5, 29.1, and 36.7, respectively, in the control group and in the groups with 0.1, 1, and 10 µg mL–1 of OPN; P = 0.24) were observed with 10 µg mL–1 of OPN. In experiment 2, significantly more cleavage (80.0 v. 71.3%; P < 0.05) and higher percentages of TM–Bl (44.6 v. 34.5%; P < 0.05) and Bl (39.2 v. 30.6%; P = 0.06) were observed with 10 µg mL–1 of OPN v. the control. Combined analysis from both experiments showed an overall effect of 10 µg mL–1 of OPN v. the control in the percentages of TM–Bl and Bl (respectively, 41.1 v. 33.3% and 37.7 v. 30.5%; P < 0.05). These results indicate that it is possible to improve the efficiency of bovine in vitro embryo production by adding the oviductal protein OPN. [ABSTRACT FROM AUTHOR]

Although removal of cumulus cells improves the efficiency of vitrification of buffalo (Bubalus bubalus) in vitro-matured (IVM) oocytes (Gasparrini et al. 2007 Anim. Reprod. Sci. 98, 335–342), the lack of cells impairs the fertilization process. Therefore, the aim of the present work was to evaluate the influence of a somatic support during in vitro fertilization (IVF) of buffalo vitrified denuded matured oocytes. Since IVF on a cumulus cells monolayer was inefficient, we verified the effects of co-culture with cumulus-enclosed oocytes (COCs). IVM buffalo oocytes (n = 316) were vitrified by the Cryotop method (Kuwayama and Kato 2000, J. Assist. Reprod. Genet. 17, 477 abst) that was recently proven suitable for buffalo oocyte cryopreservation (Attanasio et al. 2006 Reprod. Domest. Anim. 41, 302–310). Denuded buffalo oocytes were equilibrated in 10% ethylene glycol (EG) and 10% dimethyl sulfoxide (DMSO) for 3 min, transferred into 20% EG and 20% of DMSO in TCM199 with 20% fetal calf serum (FCS) + 0.5 m sucrose, loaded on Cryotops, and plunged into liquid nitrogen within 25 s. For warming, oocytes were exposed for 1 min to 1.2 m sucrose and then to decreasing concentrations of the sugar (0.6, 0.4, 0.3 m for 30 s) in TCM199 + 20% FCS. Oocytes were rinsed and allocated to IVM drops for 1.5 h. Survival rate was evaluated at this point and the oocytes that had survived (292/316 = 92.4%) were split into 2 fertilization groups: (A) approximately 5 buffalo oocytes per 50-µL drop of IVF medium, and (B) approximately 3 buffalo oocytes + 3 bovine fresh COCs per 50-µL drop of IVF medium. Since buffalo COCs easily lose their cells following IVF, for better identification we used bovine COCs that have a brighter and more compact cumulus mass. In vitro fertilization and culture were carried out as previously described (Gasparrini et al. 2007). As control, buffalo oocytes (n = 104) were in vitro-matured, fertilized, and cultured up to the blastocyst stage. On Day 1, survival rate was evaluated in the two vitrification groups; cleavage and blastocyst rates were recorded on Days 5 and 7, respectively, in all groups. The experiment was repeated 4 times. Differences in the percentages of survival, cleavage, and blastocyst formation among treatments were analyzed by chi-square test. Within vitrification groups, despite similar survival rates on Day 1 (90.6% v. 93.3%, respectively, in Groups A and B), cleavage rate was significantly improved in Group B compared to Group A (59.2% v. 45.4%, respectively; P < 0.01). Interestingly, the cleavage rate in Group B was not significantly different from that recorded in the control group (71.0%). Although blastocysts were produced in both vitrification groups (3.6% v. 4.1%, respectively, in Groups A and B), the yield was significantly lower than that of the control group (29.0%, P < 0.01). In conclusion, co-culture with bovine COC during fertilization improves the capability of buffalo denuded vitrified oocytes to cleave. [ABSTRACT FROM AUTHOR]

The competitiveness of buffalo breeding will depend on the utilization of reproductive biotechnologies that allows acceleration of genetic progress. A major factor hampering the efficiency of both artificial insemination and in vitro embryo production programs in this species is male hypofertility. Reports for several species suggest that seminal plasma contains factors that influence male fertility. Osteopontin is a glycoprotein found in several biological fluids including seminal plasma, and its presence is associated with spermatozoa concentration. In cattle, expression of osteopontin was highly correlated with bull fertility, and it was proposed to be a marker to predict male fertility (Cancel et al. 1999 Biol. Reprod. 60, 454–460). No data are available about the presence or activity of osteopontin in water buffalo. The aim of this preliminary study was to determine if osteopontin is present in buffalo semen and to evaluate whether freezing procedures cause the loss of osteopontin from spermatozoa. Semen was collected in authorized semen collection centers from 6 buffalo bulls by using an artificial vagina. A collection of bovine semen was used as a positive control. An aliquot from each sample was frozen using standard procedures for semen storage. Each ejaculate was centrifuged at 600g for 10 min at room temperature, and the supernatant was recovered and centrifuged at 10 000g for 1 h at 4C. The total protein concentration in seminal plasma and spermatozoa was determined by the Bradford method, using ovoalbumin as the standard. Proteins (50 g) were separated by electrophoresis and analyzed by western blotting (Cancel et al. 1999). Polyclonal antibodies against bovine milk osteopontin were prepared as previously described (Cancel et al. 1997 Biol. Reprod. 57, 1293–1301). The intensities of bands indicated by western blot were quantified by densitometer. Osteopontin was detected in all samples of buffalo semen. Most of the osteopontin detected was in the seminal plasma. Relative amounts of osteopontin detected in spermatozoa were 50% or less of that detected in seminal plasma; furthermore, the protein was not found in sperm from all bulls. These results suggest that most osteopontin is produced by the ampullae and seminal vesicles, similar to what was reported for cattle (Cancel et al. 1999). Semen frozen by standard procedures showed a reduction in amount of osteopontin by up to 50%. These studies suggest that the fertility-associated protein osteopontin may be useful as a sensitive tool to evaluate whether sperm storage procedures are detrimental and result in excess loss of osteopontin from sperm. In conclusion, the results have demonstrated that osteopontin is present in buffalo seminal plasma and sperm. Further studies will examine whether the expression of osteopontin is correlated with the fertility of buffalo bulls, as has been demonstrated in bovine bulls. [ABSTRACT FROM AUTHOR]