Abstract
摘要:以核移植技術複製動物之研究已發展數十年,自1997年體細胞複製羊桃莉-Dolly出生後邁入新階段,近七年來之研究進展較過去半世紀之成果更豐碩。此技術已超越優良種原之基因組複製,科學家們稱其為難以估價之試驗工具,如核潛能、細胞之去分化作用,染色質構造及功能、胚發生學及基因組操作等均需此藉由技術完成。因此複製動物之重要性非今日之成果,而係此技術可支持生物醫學之研究,尤其在胚發生學、幹細胞生物學、細胞治療及再生醫學之研究上。體細胞複製豬之技術在農業及治療研究上均具有其價值,尤其著重於生物醫學領域,已分化之細胞配合核移植技術可作為多種疾病之新治療方式。
一般冷凍胚之保存法成本高且耗時。動物體之個別細胞均攜帶一組完整個體之遺傳密碼,核移植技術能將此細胞轉成完整動物,此技術亦可支持完整遺傳密碼之完整保存,攜特殊遺傳密碼之種原,如表現霜降肌肉、抗熱及抗病基因者,均有迫切需要進行簡單又省時之完整體細胞保種,以避免滅種之風險。
許多因子影響複製豬之成功率,如卵母細胞品質、去核率、核移植操作之培養液、激活方法及影響懷孕成功與否之胎兒數等。本計畫過去雖已成功產製五頭複製豬,然複製胚移置後發育成完整個體之
Abstract: Despite its long history, the cloning of animals by nuclear transplantation is going through a “renaissance” after the birth of Dolly. The amount of work and achievements obtained in the last seven years are probably greater than those obtained in half a century of research. The importance of somatic cell nuclear transfer is, without any doubt, beyond the scope of replicating superior animal genotypes. It is an invaluable experimental tool to address fundamental scientific issues such as nuclear potency, cell de-differentiation, chromatin structure and function, epigenetics, and genome manipulation. For these reasons the importance of cloning is not for what it can achieve but for the technical support it can provide to biomedical research and in particular to the study of epigenetics, cancer and stem cell biology, cell therapy and regenerative medicine. The technology of somatic cell cloning in pigs is valuable for agricultural and therapeutic purposes. Most of the current interest towards nuclear transfer originates from the biomedical field. Recent progress in deriving and differentiating embryonic stem cells might offer new treatment for various diseases when combined with the cloning technology.
Current methods of conservation involve storage of frozen embryos but this is time consuming and costly. Each cell of animals’s body contains the full genetic code for the whole animal and nuclear transfer provides a way of converting cells to whole animals. The techniques of pig cloning will provide new methods for genetic conservation. The local breeds may contain valuable genes that confer superior performance- marbling muscle, heat tolerance or disease resistance and there is an urgent need to prevent their extinction.
The difficulty in porcine cloning has been attributed to multiple factors, including oocyte quality, enucleation rate, inadequate culture and manipulation media used during nuclear transfer, the lack of an efficient activation method, and the requirement for a minimum number of fetuses to maintain a pregnancy in the pig. Although we established cloned pig technique by nuclear transfer of somatic cell donors and produced successfully 5 cloned pigs, the efficiency of pig cloning had been extremely low, with less than 1% of transferred reconstructed embryos surviving to term. For increasing the efficiency of pig cloning, factors modified will focus on enucleation procedure, size of donor cell and activation condition.
Transgenic and cloned animals are important for scientific, pharmaceutical and agricultural purposes. Green fluorescent protein has been used as a reporter of gene expression and a fusion tag to monitor protein localization within living cells. It’s more efficient when transgenesis combined with nuclear transfer. Accurately predicting the transgene expression pattern in a genetically modified animal is vitally important in generating animal models for human disease as well as in designing livestock bioreactors for ha
Keyword(s)
體細胞
複製豬
核移植
豬間質幹細胞
Somatic Cells
Cloned pigs
Nuclear Transfer
Mesenchymal stem cells