title: Telomere elongation during morula-to-blastocyst transition in cloned porcine embryos.
abstract: Although telomeres are elongated during morula-to-blastocyst transition in cloned embryos, it is still unknown whether donor cell types have any effect on this elongation. In the present study, we examined the changes of telomere length during morula-to-blastocyst transition in cloned porcine embryos using different types of donor cells. Porcine embryonic stem-like cells (pESLCs), porcine cumulus cells (PCs), and porcine embryonic fibroblasts at passages 7 and 10 (PEF7s and PEF10s, respectively) were used as donor cells. Telomere lengths of pESLCs (35.8±1.5 kb), PCs (24.4±0.5 kb), PEF7s (18.7±0.6 kb), and PEF10s (17.2±0.1 kb) were significantly different. In contrast, telomere length in morulae derived from pESLCs (18.2±0.3 kb), PC (17.8±0.7 kb), PEF7 (18.5±0.3 kb), and PEF10 (18.4±0.4 kb) did not differ significantly. Likewise, telomeres in blastocysts derived from pESLCs (22.3±1.5 kb), PCs (23.5±2.6 kb), PEF7s (20.2±1.0 kb), and PEF10s (20.9±1.0 kb) had similar lengths. However, telomeres in blastocysts were significant longer (p<0.05) compared with morulae in each group. Relative telomerase activities of morulae derived from pESLCs (4.2±0.4), PCs (4.0±0.5), PEF7s (5.1±0.4), and PEF10s (4.9±0.4) were significantly lower (p<0.01) than those of blastocysts derived from pESLCs (8.2±1.1), PCs (8.6±0.6), PEF7s (12.5±2.9), and PEF10s (8.3±1.1). In conclusion, the telomere elongation in cloned pig embryos that occurred during morula-to-blastocyst transition may be related to the rise of telomerase activity. The telomere elongation may also be independent of the type and telomere length of the donor cell.
authors.affiliation: Department of Animal Breeding and Reproduction, NARO Institute of Livestock and Grassland Science, Ibaraki 305-0901, Japan. adipy36@affrc.go.jp
authors.forename: Thanh Quang
authors.initials: TQ
authors.lastname: Dang-Nguyen
authors.forename: Seiki
authors.initials: S
authors.lastname: Haraguchi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Akagi
authors.forename: Tamas
authors.initials: T
authors.lastname: Somfai
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kaneda
authors.forename: Shinya
authors.initials: S
authors.lastname: Watanabe
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kikuchi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Tajima
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagai
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000378:metabolism*; D019976:Cloning, Organism; D005260:Female; D009028:Morula / Q000166:cytology / Q000378:metabolism*; D013552:Swine; D019098:Telomerase / Q000378:metabolism*; D016615:Telomere / Q000378:metabolism*
chemical_list: D019098:Telomerase