R.P.C. Gerger, E.S. Ribeiro, F. Forell, L.R. Bertolini, J.L. Rodrigues, C.E. Ambrósio, M.A. Miglino, A. Mezzalira and M. Bertolini
Published February 18, 2010
Genet. Mol. Res. 9 (1): 295-302 (2010)
About the Authors
R.P.C. Gerger, E.S. Ribeiro, F. Forell, L.R. Bertolini, J.L. Rodrigues, C.E. Ambrósio, M.A. Miglino, A. Mezzalira and M. Bertolini
Corresponding author:
R.P.C. Gerger
E-mail: renatogerger@yahoo.com.br
ABSTRACT
The relationship between the level of cell confluence near the plateau phase of growth and blastocyst yield following somatic cell cloning is not well understood. We examined the effect of distinct cell culture confluence levels on in vitro development of cloned bovine embryos. In vitro-matured bovine oocytes were manually bisected and selected by DNA staining. One or two enucleated hemi-cytoplasts were paired and fused with an adult skin somatic cell. Cultured skin cells from an adult Nellore cow harvested at three distinct culture confluence levels (70-80, 80-90, and >95%) were used for construction of embryos and hemi-embryos. After activation, structures were cultured in vitro as one embryo (1 x 100%) or as aggregates of two hemi-embryos (2 x 50%) per microwell. Fusion, cleavage and blastocyst rates were compared using the χ2 test. The fusion rate for hemi-embryos (51.4%) was lower than for embryos (67.6%), with no influence of degree of cell confluence. However, blastocyst rates improved linearly (7.0, 17.5, and 29.4%) with increases in cell confluence. We conclude that degree of cell culture confluence significantly influences subsequent embryo development; use of a cell population in high confluence (>90%) for nuclear transfer significantly improved blastocyst yield after cloning.
Key words: Somatic cell nuclear transfer; Cell culture confluence; Cell cycle; Embryo aggregation; Cattle.