Comparison the effects of 5-Aza-2'-deoxycytidine and zebularine on the in vitro development, blastocyst quality, methylation pattern and conception rate on handmade cloned buffalo embryos.

In this study we treated the handmade cloned (HMC) buffalo embryos with the DNA methylation inhibitors; 5-aza-2'-deoxycytidine (AzadC) or Zebularine individually after post-fusion and during in vitro culture till eighth day. The blastocysts production rate significantly improved (p < .01) after treating embryos independently with 5 nM AzadC and 5 nM zebularine compared with 2 and 10 nM AzadC or zebularine groups, respectively. The highest cleavage rates were obtained for 5 nM treatment of AzadC and zebularine compared with other treatments and untreated control group. Quality of blastocysts were evaluated using total cell number (TCN) and the ratio of number of inner cell mass (ICM) cells/total cell number (ICM/TCN). Zebularine treatments (2/5/10 nM) significantly improved both TCN and ICM/TCN ratio compared with AzadC treatments (2/5/10 nM); however, control group TCN and ICM/TCN ratio was found lower. The methylation percentage of pDS4.1 and B. bubalis satellite DNA were comparatively more attenuated with 5 nM zebularine than 5 nM AzadC treatment. The increased in vitro development rates of the treated embryos were correlated with the decreased level of DNA methylation and the improved blastocyst quality. Following transfer of 5 nM zebularine treated embryos to 6 recipients, 4 were found to be pregnant, though the pregnancies were not carried to full term.

Development of homologous hemizona assay as a potential predictor of fertility in buffalo bulls: A preliminary approach.

Although, myriads of tests are routinely used, no single test can accurately predict fertilization potential of semen. The hemizona assay (HZA) has advantages in two ways: (a) it determines multitude traits of sperm and (b) it is a controlled sperm function test. In the present study, we developed homologous HZA in buffaloes to predict bull fertility. In this experiment, bulls with fertility rate 53.3% and 48.5% were used as control, whereas bulls with fertility rate 32.6% and 32.2% were used as test semen samples. For HZA, matching buffalo hemizonae were co-incubated with processed buffalo sperm for 4 h. The number of sperms bound to the outer surface of hemizona was determined. No significant difference was observed in sperm binding for co-incubation of same bull sperm with matching hemizona (p < .05). Significant difference in sperm binding to matching hemizona was seen, while two halves were incubated with control and test semen, respectively (p < .05). Hemizona assay index (HZAI) of test bull semen has been determined from percentage of test-sperm bound to the matching hemizona in comparison to control-sperm. For finding relation, HZAI was correlated with respective fertility rates of semen samples, and it was found that a significant positive correlation was present with r = 0.83, p < .1. A regression equation of Y = 1.39X - 55.8 (where Y = pregnancy rate of test semen sample and X = HZAI of test semen sample) was presented to predict fertility rates of unknown semen samples. Thus, HZA can be used as a potential predictor of buffalo bull fertility.

Birth of cloned calves from vitrified-warmed zona-free buffalo (Bubalus bubalis) embryos produced by hand-made cloning.

The availability of techniques for the vitrification of cloned blastocysts can improve their effective use. The present study compared the developmental competence of buffalo cloned embryos derived from adult (BAF), newborn (BNF) and fetal fibroblast (BFF) before and after vitrification. Despite similar cleavage rates among the three groups, the blastocyst rate was lower for BAF- than BNF- and BFF-derived embryos (30.2±2.2% vs 41.7±1.7% and 39.1±2.1%, respectively; P<0.01). The total cell number of BNF-derived blastocysts was significantly higher (P<0.01) than that of BFF-derived blastocysts, which, in turn, was higher (P<0.01) than that of BAF-derived blastocysts. Following transfer of vitrified-warmed blastocysts to recipients, no pregnancy was obtained with fresh (n=8) or vitrified-warmed (n=18) BAF-derived blastocysts, whereas transfer of fresh BNF- (n=53) and BFF-derived (n=32) blastocysts resulted in four and three pregnancies, respectively, which aborted within 90 days of gestation. The transfer of vitrified-warmed BNF-derived blastocysts (n=39) resulted in the live birth of a calf weighing 41kg, which is now 23 months old and has no apparent abnormality, whereas the transfer of vitrified-warmed BFF-derived blastocysts (n=18) resulted in one live birth of a calf that died within 6h. These results demonstrate that cloned buffalo embryos cryopreserved by vitrification can be used to obtain live offspring.