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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/01/15 02:11:39」(JST)

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The dictyate or dictyotene^[1] is a prolonged resting phase in oogenesis. It occurs in the stage of meiotic prophase I^[2] in ootidogenesis. It starts late in fetal life^[2] and is terminated shortly before ovulation by the LH surge.^[3] 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.^[4]

The dictyate appears to be an adaptation for efficiently removing damages in germ line DNA by homologous recombinational repair.^[5]

Translation halt

There are a lot of mRNAs that have been transcribed but not translated during dictyate.^[6] 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,^[6] and thus eIF4E can no longer interact with the other initiation factors^[7] 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,^[6] and thus translation starts, which contributes to the end of dictyate and further maturation of the oocyte.

References

^ Medical Physiology, Boron & Boulpaep, ISBN 1-4160-2328-3, Elsevier Saunders 2005. Updated edition. 1300 pages.
^ ^a ^b Thomas, Richard D, ed. (1986). Drinking Water and Health 6. Washington, D.C.: National Academies Press. p. 35. ISBN 0-309-03687-9.
^ 'Hormones and Mammalian Egg Maturation', Michael Barresi, http://8e.devbio.com/article.php?id=275, Accessed 15 Apr 08 1613
^ Titus S, Li F, Stobezki R, Akula K, Unsal E, Jeong K, Dickler M, Robson M, Moy F, Goswami S, Oktay K (2013). "Impairment of BRCA1-related DNA double-strand break repair leads to ovarian aging in mice and humans". Sci Transl Med 5 (172): 172ra21. doi:10.1126/scitranslmed.3004925. PMID 23408054.
^ 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
^ ^a ^b ^c 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
^ Lodish 2008, p.351

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English Journal

Accelerated reproductive aging in females lacking a novel centromere protein SYCP2L.

Zhou J1, Stein P2, Leu NA3, Chmátal L2, Xue J4, Ma J5, Huang X6, Lampson MA2, Schultz RM2, Wang PJ7.
Human molecular genetics.Hum Mol Genet.2015 Nov 15;24(22):6505-14. doi: 10.1093/hmg/ddv359. Epub 2015 Sep 11.
Menopause results from loss of ovarian function and marks the end of a woman's reproductive life. Alleles of the human SYCP2L locus are associated with age at natural menopause (ANM). SYCP2L is a paralogue of the synaptonemal complex protein SYCP2 and is expressed exclusively in oocytes. Here we rep
PMID 26362258

Oocyte development, meiosis and aneuploidy.

MacLennan M1, Crichton JH2, Playfoot CJ3, Adams IR4.
Seminars in cell & developmental biology.Semin Cell Dev Biol.2015 Sep;45:68-76. doi: 10.1016/j.semcdb.2015.10.005. Epub 2015 Oct 8.
Meiosis is one of the defining events in gametogenesis. Male and female germ cells both undergo one round of meiotic cell division during their development in order to reduce the ploidy of the gametes, and thereby maintain the ploidy of the species after fertilisation. However, there are some aspect
PMID 26454098

Cyclic AMP in oocytes controls meiotic prophase I and primordial folliculogenesis in the perinatal mouse ovary.

Wang Y1, Teng Z1, Li G2, Mu X3, Wang Z1, Feng L1, Niu W1, Huang K1, Xiang X1, Wang C1, Zhang H4, Xia G5.
Development (Cambridge, England).Development.2015 Jan 15;142(2):343-51. doi: 10.1242/dev.112755. Epub 2014 Dec 11.
In mammalian ovaries, a fixed population of primordial follicles forms during the perinatal stage and the oocytes contained within are arrested at the dictyate stage of meiotic prophase I. In the current study, we provide evidence that the level of cyclic AMP (cAMP) in oocytes regulates oocyte meiot
PMID 25503411

Japanese Journal

電気的活性化後のブタ体外成熟卵の発生能力

栗原隆,黒目麻由子,若生直浩 [他],OCHIAI Takashi,MIZUNO Kenichi,FUJIMURA Tatsuya,TAKAHAGI Yoichi,MURAKAMI Hiroshi,KANO Koichiro,MIYAGAWA Shuji,SHIRAKURA Ryota,NAGASHIMA Hiroshi
Journal of Reproduction and Development 48(3), 271-279, 2002
… When the nuclear phase of granulosa-cumulus-oocyte complexes (GCOCs) used in the TCM199-based IVM system and cumulus-oocyte complexes (COCs)used in the NCSU 23-based IVM system were observed, most of GCOCs were fully grown dictyate arrest oocytes (GV I, 68.6%), on the other hand, only 33.8% of COCs were at GV I stage. …
NAID 130000054964

Meiotic stage-dependent induction of chromosome aberrations in Chinese hamster primary oocytes exposed to topoisomerase II inhibitor etoposide

立野裕幸,Kamiguchi Y
MUTATION RESEARCH-FUNDAMENTAL AND MOLECULAR MECHANISMS OF MUTAGENESIS 476(1-2), 139-148, 2001-05
… Taking the time course of meiotic progression in primary oocytes following hCG injection and pharmacokinetics of VP-16 into consideration, it is likely that meiotic stages from late dictyate to diakinesis are highly sensitive to VP-16, while stages at dictyate and from metaphase I to telophase I are relatively insensitive to the drug. …
NAID 120003132246

First meiosis of early dictyate nuclei from primordial oocytes in mature and activated mouse oocytes

CZOLOWSKA R.
Zygote 4, 73-80, 1996
NAID 30040631357

Related Pictures

of the dictyate stage of mei osis data not Oocyte in resting stage, light micrograph Figure 1. 3 Schematic representation of Mammalian oocytes arrested at the dictyate Figure 1 : Human aneuploidy: mechanisms Dictyate | The Culture of Biochemistry Meiosis - divided into 3 temporally