Transcriptional activity associated with meiotic competence in fully grown mouse GV oocytes
Transcriptional activity associated with meiotic competence in fully grown mouse GV oocytes
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DOI：
10.1017/s0967199402004069
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发表时间：
2002-11-01
期刊：
影响因子：
1.7
通讯作者：
Aoki, F
中科院分区：
文献类型：
--
作者：
Liu, HL;Aoki, F
研究了云细胞和染色质组织在转录活性中的作用。此外，还研究了发育完全的小鼠卵母细胞转录活性与减数分裂能力之间的关系。在生发囊中染色质不包围核仁的完全发育的卵母细胞（nsn型卵母细胞）中检测到转录活性，但在染色质包围核仁的卵母细胞（sn型卵母细胞）中检测不到转录活性。积云细胞似乎下调了nsn型卵母细胞的转录活性，因为没有积云细胞的脱毛的nsn型卵母细胞（DO卵母细胞）的转录活性是被积云细胞包围的nst型卵母细胞（COC卵母细胞）的3倍。较高的转录活性对应于较低的萌发囊泡破坏（GVB）能力的完全成熟的卵母细胞在培养。尽管GVB发生在几乎所有（99%）的sn型卵母细胞中，但它发生在88%的COC/ nsn型卵母细胞（具有sn型构型的卵母细胞复合体）和61%的DO/ nsn型卵母细胞（具有nsn型构型的脱毛卵母细胞）中。转录活性与细胞完成第二中期（MII）进展的能力呈负相关。在GVB卵母细胞中，COC/ nsn型（81%）、DO/ sn型（66%）、COC/ nsn型（47%）和DO/ nsn型（29%）卵母细胞的第一极体（PBI）挤压率不同。经10 mM Sr2+激活后，sn型卵母细胞孤雌生殖激活的频率（46.9%）高于转录活性的nsn型卵母细胞（27.5%）。这些结果表明，转录活性对完全成熟的GV卵母细胞的减数分裂成熟和随后的激活能力有不利影响。另外，完全成熟的卵母细胞中的活性转录表明它们仍处于合成减数分裂成熟所需物质的过程中，尚未具备这些过程的能力。
The involvement of cumulus cells and chromatin organisation in transcriptional activity was investigated. In addition, the relationship between transcriptional activity and meiotic competence in fully grown mouse oocytes was surveyed. Transcriptional activity was detected in fully grown oocytes in which chromatin did not surround the nucleolus in the germinal vesicle (NSN-type oocytes), but not in oocytes in which chromatin surrounded the nucleolus (SN-type oocytes). Cumulus cells seemed to downregulate transcriptional activity in NSN-type oocytes, since transcriptional activity was 3 times greater in the denuded NSN-type oocytes free of cumulus cells (DO oocytes) than in NST-type oocytes enclosed in cumulus cells (COC oocytes). Higher transcriptional activity corresponded to lower germinal vesicle breakdown (GVB) competence of fully grown oocytes in culture. Although GVB occurred in nearly all (99%) the SN-type oocytes, it occurred in 88% of COC/NSN-type oocytes (cumulus-oocyte complex with SN-type configuration) and in 61% of DO/NSN-type oocytes (denuded oocytes with NSN-type configuration). There was a negative correlation between transcriptional activity and the capacity of a cell to complete the progression to the second metaphase (MII). In GVB oocytes, the percentage of first polar body (PBI) extrusion differed among COC/NSN-type (81%), DO/SN-type (66%), COC/NSN-type (47%) and DO/NSN-type (29%) oocytes. After activation with 10 mM Sr2+, the frequency of parthenogenetic activation was greater in SN-type oocytes (46.9%) than in transcriptionally active NSN-type oocytes (27.5%). These results suggest that transcriptional activity has a detrimental effect on the competence of meiotic maturation and subsequent activation in fully grown GV oocytes. Alternatively, active transcription in the fully grown oocytes suggests that they are still in the process of synthesising substances required for meiotic maturation and are not yet competent for these processes.