title: [Epigenetic modifications and its impact on animal cloning].
abstract: Despite recent successes in cloning various mammals and amphibians, the low efficiency of animals production and abnormal symptoms in many cloned animals are crucial problems in cloning technology. To overcome these problems, scientists focus on mechanisms of cloning. A possible cause of the low success frequency of cloning is the insufficient dedifferentiation and the inadequate reprogramming of the high differentiated adult somatic nucleus in enucleated oocytes, which caused by incomplete methylation and premature de novo remethylation of donor DNA. In cloned embryos the methylation level is higher than normal embryos, and this may cause aberrant expression of several important genes, especially imprinting genes. Study on these mechanisms is very important to improve the rate of successful cloned animals.
authors.affiliation: Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100080, China.
authors.forename: Wen-Yong
authors.initials: WY
authors.lastname: Li
authors.forename: Wei-Dong
authors.initials: WD
authors.lastname: Yu
authors.forename: Qing-Xuan
authors.initials: QX
authors.lastname: Chen
mesh_terms: D000818:Animals; D019976:Cloning, Organism; D019175:DNA Methylation / Q000235:genetics / Q000502:physiology; D044127:Epigenesis, Genetic / Q000235:genetics / Q000502:physiology*; D018392:Genomic Imprinting / Q000235:genetics / Q000502:physiology; D006801:Humans