Reducing the cytoplasmic volume during hand-made cloning adversely affects the developmental competence and quality, and alters relative abundance of mRNA transcripts and epigenetic status of buffalo (Bubalus bubalis) embryos

Hand-made cloning (HMC) is a method of choice for somatic cell nuclear transfer (SCNT). There is 20% to 50% of cytoplasm lost during manual enucleation of oocytes with HMC. To compensate, two enucleated demicytoplasts, instead of one, are fused with each donor cell, which leads to cytoplasm pooling from two different demicytoplasts. In this study, effects of using one, instead of two demicytoplasts (controls) was examined, for production of embryos using HMC. Use of one demicytoplast decreased blastocyst development (12.7 ± 1.98% compared with 47.6 ± 3.49%, P < 0.001), total cell number (TCN, 167.6 ± 14.66 compared with 335.9 ± 58.96, P < 0.01), apoptotic index (2.11 ± 0.38 compared with 3.43±0.38, P < 0.05) but did not significantly alter inner cell mass:trophectoderm cell number ratio (0.17 ± 0.01 compared with 0.19 ± 0.02) and the global content of H3K9ac and H3K27me3 of blastocysts, compared to controls. There were gene expression alterations in pluripotency- (SOX2 and NANOG but not OCT4), epigenetic- (DNMT1 but not DNMT3a and HDAC1), apoptosis- (CASPASE3 but not BCL-2 and BAX), trophectoderm- (CDX2), development- (G6PD but not GLUT1) and cell cycle check point control-related related genes (P53) compared with controls. Transfer of cloned blastocysts from one demicytoplast (n = 8) to recipients resulted in a live calf birth that after 12 days died whereas, with transfer of control blastocysts (n = 14) there was birth of a healthy calf. In conclusion, use of one, instead of two demicytoplasts for HMC, compromises in vitro developmental competence, and alters expression of several important genes affecting embryo development.

Early cleavage of handmade cloned buffalo (Bubalus bubalis) embryos is an indicator of their developmental competence and quality

Following IVF, embryos which cleave early have been shown to have higher developmental competence and quality than those that cleave relatively later across many species. We investigated the effect of time of cleavage on the developmental competence, quality, epigenetic status and gene expression in buffalo embryos produced by handmade cloning (HMC). Following classification of embryos as early cleaving (EC) or late cleaving (LC) based on whether they had cleaved or not at 24 h post in vitro culture, 54% (164/303) were found to be EC and the rest to be LC. The blastocyst rate (58.1 ± 3.4 vs 36.9 ± 1.6%, p < 0.01) and the total cell number (285.5 ± 41.9 vs 141.4 ± 36.1, p < 0.05) were higher, whereas the apoptotic index (3.6 ± 0.6 vs 12.2 ± 1.7, p < 0.01) and the global level of H3K9ac and H3K27me3 were lower (p < 0.05) in the blastocysts produced from EC than in those produced from LC embryos. The relative transcript level of CASPASE3, CASPASE7, DNMT1, DNMT3a and CDX2 was higher (p < 0.05) and that of SOX2 was lower (p < 0.05) in blastocysts produced from LC than in those produced from EC embryos, whereas the expression level of CASPASE6, P53, P21, HDAC1, OCT4 and NANOG was not significantly different between the two groups. These results show that (i) following HMC, blastocysts produced from embryos that cleave early differ from those produced from late cleaving embryos in terms of epigenetic status and expression level of many important apoptosis-, pluripotency-, trophectoderm- and epigenetics-related genes, and (ii) EC embryos are superior to LC embryos in view of their higher developmental competence and quality.

Production of wild buffalo (Bubalus arnee) embryos by interspecies somatic cell nuclear transfer using domestic buffalo (Bubalus bubalis) oocytes

The objective of this study was to explore the possibility of producing wild buffalo embryos by interspecies somatic cell nuclear transfer (iSCNT) through handmade cloning using wild buffalo somatic cells and domestic buffalo (Bubalus bubalis) oocytes. Somatic cells derived from the ear skin of wild buffalo were found to express vimentin but not keratin and cytokeratin-18, indicating that they were of fibroblast origin. The population doubling time of skin fibroblasts from wild buffalo was significantly (p < 0.05) higher, and the cell proliferation rate was significantly (p < 0.05) lower compared with that of skin fibroblasts from domestic buffalo. Neither the cleavage (92.6 ± 2.0% vs 92.8 ± 2.0%) nor the blastocyst rate (42.4 ± 2.4% vs 38.7 ± 2.8%) was significantly different between the intraspecies cloned embryos produced using skin fibroblasts from domestic buffalo and interspecies cloned embryos produced using skin fibroblasts from wild buffalo. However, the total cell number (TCN) was significantly (p < 0.05) lower (192.0 ± 25.6 vs 345.7 ± 42.2), and the apoptotic index was significantly (p < 0.05) higher (15.1 ± 3.1 vs 8.0 ± 1.4) for interspecies than that for intraspecies cloned embryos. Following vitrification in open-pulled straws (OPS) and warming, although the cryosurvival rate of both types of cloned embryos, as indicated by their re-expansion rate, was not significantly different (34.8 ± 1.5% vs 47.8 ± 7.8), the apoptotic index was significantly (p < 0.05) higher for vitrified-warmed interspecies than that for corresponding intraspecies cloned embryos (48.9 ± 7.2 vs 23.9 ± 2.8). The global level of H3K18ac was significantly (p < 0.05) lower in interspecies cloned embryos than that in intraspecies cloned embryos. The expression level of HDAC1, DNMT3a and CASPASE3 was significantly (p < 0.05) higher, that of P53 was significantly (p < 0.05) lower in interspecies than in intraspecies embryos, whereas that of DNMT1 was similar between the two types of embryos. In conclusion, these results demonstrate that wild buffalo embryos can be produced by iSCNT.