抄録
In mice and cattle, telomere length is reset during morula-blastocyst transition due to a change in telomerase activity. However, little has been known about the changes of telomere length in cloned pig embryos and the effect of donor cell type on this process. In the present study, we examined telomere length and telomerase activities of cloned porcine morulae and blastocysts using different donor cell types for nuclear transfer: 1) embryonic stem-like cells (Haraguchi et al., unpublished; ES group), 2) cumulus cells (C group), embryonic fibroblasts 3) passage 7 and 4) 10 (F7 and F10 groups, respectively). Telomere length of the donor ES (35.8 ± 1.5 kb), C (24.4 ± 0.5 kb), F7 (18.7 ± 0.6 kb) and F10 (17.2 ± 0.1 kb) cells were significantly different (P<0.05; one-way ANOVA). The ES, C, F7 and F10 morulae had shorter (P<0.05) telomere (18.2 ± 0.3 kb, 17.8 ± 0.7 kb, 18.5 ± 0.3 kb and 18.4 ± 0.4 kb, respectively) compared with ES, C, F7 and F10 blastocysts (22.3 ± 1.5 kb, 23.5 ± 2.6 kb, 20.2 ± 1.0 kb and 20.9 ± 1.0 kb). Relative telomerase activities of the ES, C, F7 and F10 morulae (4.2 ± 0.4, 4.0 ± 0.5, 5.1 ± 0.4 and 4.9 ± 0.4, respectively) were lower (P<0.01) compared with those of the ES, C, F7 and F10 blastocysts (8.2 ± 1.1, 8.6 ± 0.6, 12.5 ± 2.9 and 8.3 ± 1.1, respectively). In conclusion, restoration of telomere length in cloned pig embryos during morula-blastocyst transition was likely a telomerase-dependent process, and was independent from telomere length and type of donor cells.
