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本帖最后由 细胞海洋 于 2012-2-8 01:18 编辑 4 o7 Q" S2 _% S4 ]" S
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/ }4 {. Z6 {3 ~7 X4 t日本研究人员在最新一期美国科学杂志《发育生物学》网络版上发表报告说，他们已经找到了体细胞克隆技术成功率低（2%至3%）的原因。8 T) N! I+ C z7 m3 q' @) a8 Z
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日本理化研究所等机构研究人员发表的这一报告说，他们观察了330个小鼠的克隆胚胎细胞分裂情形，结果发现细胞核内染色体异常分配，第三次分裂时（从一个细胞逐次分裂为8个细胞），约80%的胚胎细胞出现异常，因而未能发育成小鼠。而在普通胚胎中，这一时期的异常率约为30%。& ]: Y/ i& K5 r) _8 s" s
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参与这一研究的大阪大学特聘副教授山县一夫说：“由于弄清了原因，在很早的阶段就可以识别出正常的胚胎，从而提高成功率。染色体的分配异常也被认为是不孕的一个原因，新发现也许有助于帮助弄清不孕的详细机制。”
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人们普遍希望将体细胞克隆技术广泛应用在畜产业、医疗和灭绝动物复活等领域，著名的克隆羊多利就是世界上第一头体细胞克隆动物。然而，距多利诞生已过去15年，这种技术依然不成熟，成功率仅有2%至3%。（来源：新华网 蓝建中）
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3 h* f8 c" v5 z$ t- n6 N% O) fAbnormal chromosome segregation at early cleavage is a major cause of the full-term developmental failure of mouse clones, i3 e1 }. a; @8 b
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To clarify the causes of the poor success rate of somatic cell nuclear transfer (SCNT), we addressed the impact of abnormalities observed at early cleavage stages of development on further full-term development using ‘less-damage’ imaging technology. To visualize the cellular and nuclear division processes, SCNT embryos were injected with a mixture of mRNAs encoding enhanced green fluorescent protein coupled with α-tubulin (EGFP-α-tubulin) and monomeric red fluorescent protein 1 coupled with histone H2B (H2B-mRFP1) and monitored until the morula/blastocyst stage three-dimensionally. First, the rate of development of SCNT embryos and its effect on the full-term developmental ability were analyzed. The speed of development was retarded and varied in SCNT embryos. Despite the rate of development, SCNT morulae having more than eight cells at 70 h after activation could develop to term. Next, chromosomal segregation was investigated in SCNT embryos during early embryogenesis. To our surprise, more than 90% of SCNT embryos showed abnormal chromosomal segregation (ACS) before they developed to morula stage. Importantly, ACS per se did not affect the rate of development, morphology or cellular differentiation in preimplantation development. However, ACS occurring before the 8-cell stage severely inhibited postimplantation development. Thus, the morphology and/or rate of development are not significant predictive markers for the full-term development of SCNT embryos. Moreover, the low efficiency of animal cloning may be caused primarily by genetic abnormalities such as ACS, in addition to the epigenetic errors described previously.
$ M* G* i' C3 Vhttp://www.sciencedirect.com/sci ... i/S0012160612000048 2 w' r! s7 p3 h) N
2 B5 U9 |( e0 B4 S7 }13楼原文 感谢songzxj 提供 |
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发表于 2012-2-3 14:41
发表于 2012-3-31 10:56
