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Nuclear reprogramming by somatic cell nuclear transfer--the cattle story.
X C Tian1, S L Smith, S Q Zhang
1Department of Animal Science/Center for Regenerative Biology, University of Connecticut, Storrs, CT, USA. Xiuchun.tian@uconn.edu
Society of Reproduction and Fertility Supplement
|May 12, 2007
Summary
Nuclear reprogramming in cloned bovine embryos shows early success, but later developmental gene expression errors may occur. This impacts cloning efficiency in agriculture and biomedicine.
Area of Science:
- Reproductive biology
- Developmental biology
- Genetics
Background:
- Somatic cell nuclear transfer (cloning) aims to restore cellular totipotency via nuclear reprogramming.
- Current cloning techniques suffer from low efficiency, necessitating research into reprogramming deficiencies.
Purpose of the Study:
- To investigate gene expression patterns in cloned bovine embryos and offspring.
- To compare gene expression between cloned and conventionally produced bovine embryos/offspring.
Main Methods:
- Analysis of candidate genes (imprinted and X-linked) and global gene expression in cloned bovine embryos and term calves.
- Comparison with conventionally produced embryos and nuclear donor cells.
Main Results:
- Cloned blastocysts exhibit gene expression profiles similar to naturally fertilized embryos, suggesting successful early reprogramming.
- Aberrant expression of H19, Igf2r, and X-linked genes was observed in term cloned calves.
- Gene expression in cloned blastocysts differs significantly from their nuclear donor cells.
Conclusions:
- Nuclear reprogramming appears largely successful by the blastocyst stage in cloned bovine embryos.
- Gene expression abnormalities may arise during later re-differentiation or from subtle initial reprogramming errors.
- Understanding these deficiencies is crucial for improving cloning efficiency.
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