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1、植物细胞全能性第1页，共21页，编辑于2022年，星期六n细胞全能性（cell totipotency）比较权威的定义是1984年国际组织培养协会做出的：“细胞全能性为细胞的某种特征，有这种能力的细胞保留形成有机体所有细胞类型的能力”。第2页，共21页，编辑于2022年，星期六nGerm cells are often described as the ultimate totipotent stem cell.nThe totipotent potential of germ cells is evident in the mature eggs of many animals,where
2、somatic gene products,including those required for the patterning of the early embryo,are present but not utilized until fertilization.第3页，共21页，编辑于2022年，星期六nThere are three features contribute to the germ cells unique ability to retain the totipotent potential necessary for the conception of an enti
3、rely new organism.第4页，共21页，编辑于2022年，星期六n1、Transcriptional Repression Restricts Germ Cell Faten2、Germ Cells Rely on Their Nichen3、Conserved Regulators Control the Germ Cell Program第5页，共21页，编辑于2022年，星期六第6页，共21页，编辑于2022年，星期六Transcriptional Repression Restricts Germ Cell Fate第7页，共21页，编辑于2022年，星期六Transcr
4、iptional Repression Restricts Germ Cell Fate第8页，共21页，编辑于2022年，星期六Germ Cells Rely on Their NichenThe niche provides the necessary signals that regulate the balance between self-renewal and differentiation that is needed for proper progression through gametogenesis.第9页，共21页，编辑于2022年，星期六Germ Cells Rely
5、 on Their Niche第10页，共21页，编辑于2022年，星期六Conserved Regulators Control the Germ Cell ProgramnmRNAs coding for essential germline factors have been identified in germ granules,and many of the protein components of germ granules are implicated in various aspects of mRNA regulation.nThe specific mechanisms
6、involved,however,remain poorly understood and are likely to be complex.第11页，共21页，编辑于2022年，星期六Conserved Regulators Control the Germ Cell Program第12页，共21页，编辑于2022年，星期六Conserved Regulators Control the Germ Cell Program第13页，共21页，编辑于2022年，星期六Conserved Regulators Control the Germ Cell ProgramnFor example,
7、the DEAD box helicase Vasa,a widely conserved component of germ granules,is required for the expression of several proteins in Drosophila,including Gurken in oocytes and Nanos in the germ plasm of embryos.第14页，共21页，编辑于2022年，星期六Conserved Regulators Control the Germ Cell ProgramnVasa regulation of Gur
8、ken depends on an interaction with the translation factor eIF5B,suggesting that Vasa functions directly in the translational activation of Gurken RNA.第15页，共21页，编辑于2022年，星期六Conserved Regulators Control the Germ Cell ProgramnVasa regulation of Nanos,however,does not require bindingto eIF5B but require
9、s recruitment of other germ granule components to the germ plasm,including Tudor.第16页，共21页，编辑于2022年，星期六A draft gene regulatory network for cellular totipotency reprogrammingnControls(or functional links,relationships,and links)represent how proteins regulate or control one another on the graph,inclu
10、ding events of functional regulation,chemical reactions,and proteinprotein interactions.nNodes represent proteins,small molecules,and other cell objects.第17页，共21页，编辑于2022年，星期六A draft gene regulatory network for cellular totipotency reprogramming第18页，共21页，编辑于2022年，星期六第19页，共21页，编辑于2022年，星期六第20页，共21页，编辑于2022年，星期六Thank you第21页，共21页，编辑于2022年，星期六