introduction & objectives materials & methods results conclusions

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incubation in demecolcine solution. Cells were transferred into enucleated oocytes, followed by electric fusion using a single DC pulse of 1.6 kV/cm for 70 μs.
V. Bordignon2, M. Albornoz1, C. Colato1, N. El-Beyrouthi1 J. I. Mellano1, A. Meltsas1, F. Mellano1, P. H. Mellano1 M. L. Mellano1, M. A. Mellano1, J. C. Mellano1, H. Baldassarre2

Germinal Biotech, Marcos Paz, Buenos Aires, Argentina 2 McGill University, Ste. Anne de Bellevue, Quebec, Canada 1

INTRODUCTION & OBJECTIVES Increased histone acetylation by exposure to inhibitors of deacetylase enzymes has been reported to improve development of embryos produced by somatic cell nuclear transfer (SCNT). However, the response to such treatment seems to vary according to the specie, cell line, and type of inhibitor used. The main objective of this study was to evaluate if treatment with the histone deacetylase inhibitor Scriptaid could improve the development to term of sheep SCNT-embryos.

MATERIALS & METHODS The two fibroblast cell lines used in this study were obtained from skin biopsies collected from 2 adult rams of the Santa Ines breed. Oocytes were collected by laparoscopic ovum pick-up (LOPU) from 30 crossbred sheep that were hormonally stimulated using FSH and eCG (1,2). Oocytes were matured in vitro for 24h in TCM 199 supplemented with hormones and 10% fetal bovine serum, at 38.5°C in 5% CO2. Matured oocytes were denuded and enucleated after incubation in demecolcine solution. Cells were transferred into enucleated oocytes, followed by electric fusion using a single DC pulse of 1.6 kV/cm for 70 μs. The reconstructed embryos were then activated using ionomycin (5 μM/5 minutes) followed by cycloheximide (10 μg/ml) and cytochalasin B (7.5 μg/ml ) for 4-5 h and then half went straight into culture in mSOF media (Control); while half of the reconstructed embryos were exposed to 500 nM Scriptaid for 10-12 h starting after ionomycin treatment. Subsequent to culture in mSOF ± Scriptaid as above, selected embryos were finally transferred into the oviducts of synchronized recipients within 24h from fusion. Pregnancy was detected and monitored for the first three months by transrectal ultrasound scanning. All recipients delivered by elective C-section which was scheduled around day 148 of gestation; fetal lung maturation was induced with 3 x 4mg injections of dexamethasone starting -36h from C-section. Oxygen therapy was provided to lambs exhibiting breathing difficulties in the first 48h.

RESULTS Results are shown in Table 1. Initial pregnancy was significantly higher in the Scriptaid Group (40 vs. 12.5%, p

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