Search

Abstract: The present study was conducted primarily to optimize electrofusion conditions for efficient production of zona-free nuclear transfer embryos in buffalos (Bubalus bubalis). We found that 4V AC current for proper triplet alignment and single step fusion method, using a single DC pulse of 3.36 kV/cm for 4-μs duration, produced the most convincing results for efficient reconstitution of zona-free cloned embryos. Lysis rate was very high (84.28 ± 2.59%) when triplets were in physical contact with negative electrode after applying DC current, however, cleavage rate and blastocyst rate were found to be similar when the triplets were not in physical contact with either positive or negative electrodes or when they were in physical contact with the positive electrode. Significant improvement in blastocyst production was observed when the somatic cell faced the positive electrode than when it faced the negative electrode (39.17 ± 2.74% vs. 25.91 ± 2.00%, respectively) during electrofusion. Similarly, the blastocyst rate (52.0 ± 3.4%) was found to be significantly higher when reconstructed embryos were activated 6 h post electrofusion as compared to 0, 2, 4 and 8 h (16.04 ± 6.3%; 18.36 ± 1.4%; 22.44 ± 3.7% and 30.02 ± 4.6%, respectively). This study establishes the application of zona-free nuclear transfer procedures for the production of handmade cloned buffalo embryos through optimization of electrofusion parameters and post fusion holding time for enhancing their preimplantation development. [Copyright &y& Elsevier]

Abstract: Handmade cloning (HMC), a simple, micromanipulation-free cloning technique, has been applied for the production of cloned embryos and offspring in many livestock species. The objective of the present study was to compare the effect of donor cell type on developmental competence of HMC embryos and to explore the possibility of establishing pregnancies using these embryos in buffalo. After technical optimization of the HMC procedure for in vitro development of cloned blastocysts, various donor cells were compared for their developmental efficiency. Using buffalo fetal-, newborn-, adult fibroblasts and cumulus cells, blastocyst production rates obtained from reconstructed embryos were 24.0±1.8% (35/145), 33.0±8.0% (56/163), 21.0±9.3% (29/133) and 49.6±1.9% (77/154), respectively. Blastocyst rates were higher (P <0.05) in cumulus cell reconstructed embryos in comparison to those derived from fetal or adult fibroblasts. Pregnancy diagnosis (transrectal ultrasonography) was carried out at Day 40 of gestation. Following transfer of HMC embryos reconstructed using newborn fibroblasts 25% (2/8) buffaloes were pregnant and are at Days 201 and 94 of gestation, whereas after transfer of HMC embryos reconstructed using fetal fibroblasts, 20% (1/5) buffaloes were pregnant and are at Day 73 of gestation. In conclusion, HMC could be a simple and efficient technique for the production of cloned embryos for establishing pregnancies in buffalo. [Copyright &y& Elsevier]

Abstract: The possibility of producing interspecies handmade cloned (iHMC) embryos by nuclear transfer from donor cells of cattle, goat and rat using buffalo oocytes as recipient cytoplasts was explored. Zona-free buffalo oocytes were enucleated by protrusion cone-guided bisection with a microblade. After electrofusion with somatic cells, reconstructed oocytes were activated by calcimycin A23187, treated with 6-dimethylaminopurine and were cultured in K-RVCL-50® medium for 8 days. Although the cleavage rate was not significantly different when buffalo, cattle, goat or rat cells were used as donor nuclei (74.6±3.8, 82.8±5.3, 86.0±4.9 and 82.3±3.6%, respectively), the blastocyst rate was significantly higher (P <0.01) for buffalo (51.4±2.6) than for cattle (3.5±1.0) or the goat (2.2±0.9), whereas none of the embryos crossed the 32-cell stage when rat cells were used. However, the total cell number was similar for buffalo–buffalo (175.0±5.07) and cattle–buffalo embryos (178.0±11.84). Following transfer of 3 buffalo–buffalo embryos each to 6 recipients, 3 were found to be pregnant, though the pregnancies were not carried to full term. These results suggest that interspecies blastocyst stage embryos can be produced by iHMC using buffalo cytoplasts and differentiated somatic cells from cattle and goat and that the source of donor nucleus affects the developmental competence of interspecies embryos. [Copyright &y& Elsevier]