Developmentally regulated loss and reappearance of immunoreactive somatic histone H1 on chromatin of bovine morula-stage nuclei following transplantation into oocytes
Developmentally regulated loss and reappearance of immunoreactive somatic histone H1 on chromatin of bovine morula-stage nuclei following transplantation into oocytes
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DOI：
10.1095/biolreprod61.1.22
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发表时间：
1999-07-01
影响因子：
3.6
通讯作者：
Smith, LC
中科院分区：
文献类型：
--
作者：
Bordignon, V;Clarke, HJ;Smith, LC
牛卵母细胞和卵裂球染色质的一个区别是组蛋白H1的体细胞亚型在卵母细胞中检测不到，并且在第四个细胞周期中组装到胚胎染色质上。我们研究了当含有体细胞H1的细胞核移植到卵母体中时，这种染色质修饰是否被逆转。从桑葚胚中获得的供体细胞核在卵母体孤雌活化前后的不同时间与卵母体融合。融合后，免疫反应性H1无法检测到，在卵母细胞激活前进行融合时，与激活后数小时（宿主卵母细胞处于与间期相对应的阶段）进行融合时相比，其丢失速度更快。尽管免疫反应性H1的丢失与DNA复制和转录无关，但将重建的卵母细胞暴露于环己亚胺或6-甲氨基嘌呤（6-DMAP）中可以延缓移植细胞核中免疫反应性H1的丢失。在核移植胚胎的进一步发育过程中，体细胞H1在2细胞和4细胞阶段仍然无法检测到，并且在8至16细胞阶段重新出现在染色质上，正如之前在未处理的胚胎中观察到的那样。我们得出的结论是，卵母细胞细胞质中的因子能够修饰桑葚胚染色质，使体细胞H1变得无法检测到，并且这些因子的数量或活性随着活化卵母细胞的时间而下降。
One difference between chromatin of bovine oocytes and blastomeres is that somatic subtypes of histone H1 are undetectable in oocytes and are assembled onto embryonic chromatin during the fourth cell cycle. We investigated whether this chromatin modification is reversed when nuclei containing somatic H1 are transplanted into ooplasts. Donor nuclei obtained from morula-stage bovine embryos were fused to ooplasts at different times before and after parthenogenetic activation of the ooplasts. After fusion, immunoreactive H1 became undetectable, and the loss occurred more rapidly when fusion was performed near the time of ooplast activation compared with several hours after activation, when the host oocytes were at a stage corresponding to interphase. Although the loss of immunoreactive H1 occurred independently of DNA replication and transcription, exposure of reconstructed oocytes to cycloheximide or 6-dymethylaminopurine (6-DMAP) delayed the loss of immunoreactive H1 from transplanted nuclei. During further development of nuclear-transplant embryos, somatic H1 remained undetectable at the 2- and 4-cell stages, and it reappeared on the chromatin at the 8- to 16-cell stage, as previously observed in unmanipulated embryos. We conclude that factors in oocyte cytoplasm are able to modify morula chromatin so that somatic H1 becomes undetectable, and that the amount or activity of these factors declines over time in activated ooplasts.