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The dictyate or dictyotene〔Medical Physiology, Boron & Boulpaep, ISBN 1-4160-2328-3, Elsevier Saunders 2005. Updated edition. 1300 pages.〕 is a prolonged resting phase in oogenesis. It occurs in the stage of meiotic prophase I in ootidogenesis. It starts late in fetal life〔 and is terminated shortly before ovulation by the LH surge.〔'Hormones and Mammalian Egg Maturation', Michael Barresi, http://8e.devbio.com/article.php?id=275, Accessed 15 Apr 08 1613〕 Thus, although the majority of oocytes are produced in female fetuses before birth, these pre-eggs remain arrested in the dictyate stage until puberty commences and the cells complete ootidogenesis. In both mouse and human, oocyte DNA of older individuals has substantially more double-strand breaks than that of younger individuals. The dictyate appears to be an adaptation for efficiently removing damages in germ line DNA by homologous recombinational repair.〔Harris Bernstein, Carol Bernstein and Richard E. Michod (2011). Meiosis as an Evolutionary Adaptation for DNA Repair. Chapter 19 in DNA Repair. Inna Kruman editor. InTech Open Publisher. DOI: 10.5772/25117 http://www.intechopen.com/books/dna-repair/meiosis-as-an-evolutionary-adaptation-for-dna-repair〕 ==Translation halt== There are a lot of mRNAs that have been transcribed but not translated during dictyate.〔(Molecule.org - Maskin Is a CPEB-Associated Factor that Transiently Interacts with eIF-4E ) Barbara Stebbins-Boaz,1 Quiping Cao,1 Cornelia H de Moor,1 Raul Mendez,1 and Joel D Richter1〕 Shortly before ovulation, the oocyte of interest activates these mRNA strains. ===Biochemistry mechanism=== Translation of mRNA in dictyate is partly explained by molecules binding to sites on the mRNA strain, which results in that initiation factors of translation can not bind to that site. Two such molecules, that impedes initiation factors, are CPEB and ''maskin'', which bind to CPE (cytoplasmic polyadenylation element). When these two molecules remain together, then maskin binds the initiation factor eIF-4E,〔 and thus eIF4E can no longer interact with the other initiation factors〔Lodish 2008, p.351〕 and no translation occurs. On the other hand, dissolution of the CPEB/maskin complex leads to eIF-4E binding to the initiation factor eIF-4G,〔 and thus translation starts, which contributes to the end of dictyate and further maturation of the oocyte. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「The dictyate or dictyoteneMedical Physiology, Boron & Boulpaep, ISBN 1-4160-2328-3, Elsevier Saunders 2005. Updated edition. 1300 pages. is a prolonged resting phase in oogenesis. It occurs in the stage of meiotic prophase I in ootidogenesis. It starts late in fetal life and is terminated shortly before ovulation by the LH surge.'Hormones and Mammalian Egg Maturation', Michael Barresi, http://8e.devbio.com/article.php?id=275, Accessed 15 Apr 08 1613 Thus, although the majority of oocytes are produced in female fetuses before birth, these pre-eggs remain arrested in the dictyate stage until puberty commences and the cells complete ootidogenesis.In both mouse and human, oocyte DNA of older individuals has substantially more double-strand breaks than that of younger individuals.The dictyate appears to be an adaptation for efficiently removing damages in germ line DNA by homologous recombinational repair.Harris Bernstein, Carol Bernstein and Richard E. Michod (2011). Meiosis as an Evolutionary Adaptation for DNA Repair. Chapter 19 in DNA Repair. Inna Kruman editor. InTech Open Publisher. DOI: 10.5772/25117 http://www.intechopen.com/books/dna-repair/meiosis-as-an-evolutionary-adaptation-for-dna-repair==Translation halt==There are a lot of mRNAs that have been transcribed but not translated during dictyate.(Molecule.org - Maskin Is a CPEB-Associated Factor that Transiently Interacts with eIF-4E ) Barbara Stebbins-Boaz,1 Quiping Cao,1 Cornelia H de Moor,1 Raul Mendez,1 and Joel D Richter1 Shortly before ovulation, the oocyte of interest activates these mRNA strains.===Biochemistry mechanism=== Translation of mRNA in dictyate is partly explained by molecules binding to sites on the mRNA strain, which results in that initiation factors of translation can not bind to that site. Two such molecules, that impedes initiation factors, are CPEB and ''maskin'', which bind to CPE (cytoplasmic polyadenylation element). When these two molecules remain together, then maskin binds the initiation factor eIF-4E, and thus eIF4E can no longer interact with the other initiation factorsLodish 2008, p.351 and no translation occurs. On the other hand, dissolution of the CPEB/maskin complex leads to eIF-4E binding to the initiation factor eIF-4G, and thus translation starts, which contributes to the end of dictyate and further maturation of the oocyte.」の詳細全文を読む スポンサード リンク
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