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Generation and repair of AID-initiated DNA lesions in B lymphocytes

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《医学前沿（英文）》 2014年第8卷第2期页码 201-216 doi: 10.1007/s11684-014-0324-4

摘要：

Activation-induced deaminase (AID) initiates the secondary antibody diversification process in B lymphocytes. In mammalian B cells, this process includes somatic hypermutation (SHM) and class switch recombination (CSR), both of which require AID. AID induces U:G mismatch lesions in DNA that are subsequently converted into point mutations or DNA double stranded breaks during SHM/CSR. In a physiological context, AID targets immunoglobulin (Ig) loci to mediate SHM/CSR. However, recent studies reveal genome-wide access of AID to numerous non-Ig loci. Thus, AID poses a threat to the genome of B cells if AID-initiated DNA lesions cannot be properly repaired. In this review, we focus on the molecular mechanisms that regulate the specificity of AID targeting and the repair pathways responsible for processing AID-initiated DNA lesions.

关键词： class switch recombination somatic hypermutation activation-induced deaminase DNA repair genomic instability

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Oocyte-associated transcription factors in reprogramming after somatic cell nuclear transfer: a review

Fengxia YIN,Hui LIU,Shorgan BOU,Guangpeng LI

《农业科学与工程前沿（英文）》 2014年第1卷第2期页码 104-113 doi: 10.15302/J-FASE-2014003

摘要： Oocytes are unique cells with the inherent capability to reprogram nuclei. The reprogramming of the somatic nucleus from its original cellular state to a totipotent state is essential for term development after somatic cell nuclear transfer. The nuclear-associated factors contained within oocytes are critical for normal fertilization by sperm or for somatic cell nuclear reprogramming. The chromatin of somatic nuclei can be reprogrammed by factors in the egg cytoplasm whose natural function is to reprogram sperm chromatin. The oocyte first obtains its reprogramming capability in the early fetal follicle, and then its capacity is enriched in the late growth phase and reaches its highest capability for reprogramming as fully-grown germinal vesicle oocytes. The cytoplasmic milieu most likely contains all of the specific transcription and/or reprogramming factors necessary for cellular reprogramming. Certain transcription factors in the cytoplast may be critical as has been demonstrated for induced pluripotent stem cells. The maternal pronucleus exerts a predominant, transcription-dependent effect on embryo cytofragmentation, with a lesser effect imposed by the ooplasm and the paternal pronucleus. With deep analysis of transcriptomics in oocytes and early developmental stage embryos more maternal transcription factors inducing cellular reprogramming will be identified.

关键词： nuclear reprogramming somatic cell transcription factors transcriptomics

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Factors influencing the somatic cell nuclear transfer efficiency in pigs

Yong JIN, Manling ZHANG, Xinrong JU, Shuang LIANG, Qiang XIONG, Lihua ZHAO, Xiaowei NIE, Daorong HOU, Qiang LIU, Junzheng WANG, Chenyu WANG, Xiaokang LI, Lining ZHANG, Xiaorui LIU, Ying WANG, Haiyuan YANG, Yifan DAI, Rongfeng LI

《农业科学与工程前沿（英文）》 2019年第6卷第1期页码 73-80 doi: 10.15302/J-FASE-2018220

摘要：

Using a data set from our laboratory, we assessed the effects of several factors on pig cloning efficiency. The results demonstrated that cells at high confluence (>90%) used as donor cell resulted in higher pregnancy rate, delivery rate and overall cloning efficiency (number of live offspring born per reconstructed embryo transferred to recipients) compared with the cells at 60% to 79% confluence and 80% to 89% confluence. Cells with four, five and six passages compromised the pregnancy and delivery rates compared with first passage cells. The number of blastocysts transferred by somatic cell nuclear transfer (SCNT) did not significantly affect the cloning efficiency, but transfer of blastocyst derived from culture 5 d after SCNT achieved a significantly higher pregnancy rate compared with one to two cell SCNT embryos from overnight culture. The highest pregnancy rate, delivery rate and the largest litter size were obtained when Bama Miniature pig fibroblasts were used as donor cells and Landrace/Yorkshire hybrid gilts were used as recipients. Recipients treated with chemicals for estrus synchronization had higher pregnancy rates compared with untreated recipients. Our data might be helpful for improving SCNT efficiency in pigs.

关键词： blastocyst donor cell estrus synchronization pregnancy rate pig cloning somatic cell nuclear transfer

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Factors affecting early embryonic development in cattle: relevance for bovine cloning

Yanna DANG, Kun ZHANG

《农业科学与工程前沿（英文）》 2019年第6卷第1期页码 33-41 doi: 10.15302/J-FASE-2018228

摘要：

Female infertility represents a major challenge for improving the production efficiency in the dairy industry. Historically, fertility has declined whereas milk yield has increased tremendously due to intensive genetic selection. evidence reveals about 60% pregnancy loss takes place during the first month following fertilization. Meanwhile, early embryo development is significant for somatic cell nuclear transfer in cattle as a large proportion of cloned embryos fail to develop beyond peri-implantation stage. Oocyte quality is of utmost importance for the early embryo to develop to term for both fertilized and cloned embryos. Epigenetic reprogramming is a key process occurring after fertilization and critical roles of epigenetic modifiers during preimplantation development are now clear. Incomplete epigenetic reprogramming is believed to be a major limitation to cloning efficiency. Treatment of cloned embryos with epigenetic modifying drugs (e.g., Trichostatin A) could greatly improve cloning efficiency in both mice and cattle. Recently, the rapid progress in high-throughput sequencing technologies has enabled detailed deciphering of the molecular mechanisms underlying these events. The robust efficiency of genomic editing tools also presents an alternative approach to the functional annotation of genes critical to early development.

关键词： bovine cloning embryo development somatic cell nuclear transfer X-inactive specific transcript

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诱导性多潜能干细胞(iPS)研究：现状与展望

韩为东,赵亚力,付小兵

《中国工程科学》 2009年第11卷第5期页码 81-87

摘要：

通过特定的基因组合与转染可以将已分化的体细胞诱导重编程为多潜能干细胞（iPS），是近年来干细胞研究领域最令人瞩目的一项新的干细胞制造技术。与胚胎干细胞（ES）不同，iPS细胞的制造不需要毁损胚胎，因而不会涉及更多的伦理学问题。iPS的出现不仅为体细胞重编程去分化机制的研究注入了新的活力，而且为疾病发生发展相关机制研究与特异的细胞治疗，特别是再生医学带来新的曙光。目前，iPS的研究尚处于初级阶段，文章就iPS的研究现状与应用前景进行综述和展望。

关键词：体细胞重编程 iPS细胞

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Transcriptome resources and genome-wide marker development for Japanese larch (

Wanfeng LI,Suying HAN,Liwang QI,Shougong ZHANG

《农业科学与工程前沿（英文）》 2014年第1卷第1期页码 77-84 doi: 10.15302/J-FASE-2014010

摘要： While the differential responses of trees to changes in climatic and environmental conditions have been demonstrated as they age, the underlying mechanisms and age control of tree growth and development are complex and poorly understood particularly at a molecular level. In this paper, we present a transcriptome analysis of , a deciduous conifer that is widely-grown in the northern hemisphere and of significant ecological and economic value. Using high-throughput RNA sequencing, we obtained about 26 million reads from the stems of 1-, 2-, 5-, 10-, 25- and 50-year-old trees. Combining these with the published Roche 454 sequencing reads and the expressed sequence tags (both mainly from embryogenic cell cultures), we assembled 26670549 reads into 146786 transcripts, of which we annotated 79182 to support investigations of the molecular basis of tree aging and adaption, somatic embryogenesis and wood formation. Using these sequences we also identified many single-nucleotide polymorphisms, simple sequence repeats, and insertion and deletion markers to assist breeding and genetic diversity studies of .

关键词： Larix transcriptome age wood formation somatic embryogenesis molecular marker

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The ecological adaptability of cloned sheep to free-grazing in the Tengger Desert of Inner Mongolia, China

Xinxin LI,Huijuan WANG,Guanghua SU,Zhuying WEI,Chunling BAI,Wuni-MENGHE,Yanhui HOU,Changqing YU,Shorgan BOU,Guangpeng LI

《农业科学与工程前沿（英文）》 2014年第1卷第3期页码 191-200 doi: 10.15302/J-FASE-2014029

摘要： Since the birth of the first cloned sheep, somatic cell nuclear transfer technology has been successfully used to clone a variety of mammals. Cloned livestock have no apparent health risks, and the quality and safety of the cloned animal products are similar to non-cloned animals. The social behavior and environmental adaptability of postnatal cloned animals, especially when used for grassland farm production purposes, is unknown. In the present study, the cloned Dorper sheep equipped with GPS location devices were free-grazed in a harsh natural environment similar to conditions commonly experienced by Mongolian sheep. The main findings of this research were as follows. (1) Under free-grazing conditions, the cloned sheep showed excellent climatic and ecological adaptability. In extreme temperature conditions ranging from -30 to 40°C, the cloned sheep maintained acceptable body condition and behaved as other sheep. (2) The cloned sheep quickly adapted from a herd feeding strategy to the harsh environment and quickly exhibited a grazing regimen as other free-grazing sheep. (3) The cloned sheep exhibited free-grazing patterns and social behavior as other sheep. (4) The cloned sheep in the harsh environment thrived and produced healthy lambs. Overall, the cloned Dorper sheep exhibited excellent ecological adaptation, which is an important consideration for breeding meat sheep by cloning. The Dorper sheep readily adapted to the free-grazing conditions on the Mongolian plateau grassland, which attests to their ability to withstand harsh environmental conditions.

关键词： somatic cell nuclear transfer free-grazing synchronization Dorper sheep cloned animal ecology