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Remarkable differences in telomere lengths among cloned cattle derived from different cell types
Norikazu Miyashita1, Kazuho Shiga, Miharu Yonai
1Laboratory of Cellular Biology, National Institute of Animal Industry, Kukisaki, Ibaraki 305-0901, Japan. nmiya@affrc.go.jp
Biology of Reproduction
|May 22, 2002
Summary
Cloning cattle using somatic cells does not fully reset cellular aging, as telomere lengths vary significantly. Nuclear transfer often elongates telomeres, but the extent depends on donor cell type and initial telomere length.
Area of Science:
- Reproductive biology
- Cellular biology
- Genetics
Background:
- Cloned animals raise questions about cellular senescence and lifespan.
- Telomere length is a key indicator of cellular aging.
Purpose of the Study:
- To investigate telomere length variations in cloned cattle derived from different donor cell types.
- To determine if cloning resets the cellular aging clock (telomere length).
Main Methods:
- Produced 14 cloned cattle using nuclei from muscle, oviduct, mammary, and ear skin cells.
- Analyzed telomere lengths using Southern blot with a telomere-specific probe.
Main Results:
- Significant variation in telomere lengths was observed among cloned cattle.
- Cloned cattle from old bull muscle cells had longer telomeres than the donor, but within normal calf variation.
- Cloned cattle from old cow oviductal/mammary cells had shorter telomeres than controls.
- Cloning generally showed less telomere erosion or even elongation from nuclear transfer to birth compared to fertilization to birth in controls.
- Embryonic cell-cloned cattle and offspring had longer telomeres than age-matched controls.
Conclusions:
- Cloning does not necessarily restore the telomere clock to a youthful state.
- Nuclear transfer commonly triggers telomere elongation, influenced by donor cell type.
- Variations in telomere length among cloned cattle are due to donor cell differences and cloning-induced elongation.