Smith L C, Meirelles F V, Bustin M, Clarke H J
Centre de Recherche en Reproduction Animale, Faculté de Médecine, Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada.
J Exp Zool. 1995 Nov 1;273(4):317-26. doi: 10.1002/jez.1402730406.
We have examined the distribution of somatic histone H1 in bovine oocytes and preimplantation embryos, using an antibody that recognizes histone H1 subtypes present in somatic cells. Immunoreactive H1 was not detectable on the chromosomes of metaphase II of meiosis nor in the nuclei of early cleavage-stage embryos. In most embryos, immunoreactive H1 was assembled onto embryonic chromatin during the fourth to sixth cell cycle after fertilization. No immunoreactive somatic histone H1 was detected, however, when embryos were incubated in the presence of alpha-amanitin beginning early during the fourth cell cycle. These results indicate that somatic subtypes of histone H1 are assembled onto embryonic chromatin in a developmentally regulated manner that requires embryonic transcription. Aphidicolin, an inhibitor of DNA replication, also inhibited the assembly of somatic histone H1 onto chromatin when present at early stages of the 4th cell cycle. It is suggested that, because the bulk of histone gene expression in proliferating cells occurs during DNA replication, expression of genes encoding immunoreactive H1 is inhibited in embryos blocked before or soon after entering the S-phase. These findings on the control of somatic histone H1 assembly onto chromatin in cattle show a remarkable similarity to those found in the mouse. Such evolutionary conservation suggests that the somatic histone H1 complement of chromatin may regulate critical aspects of chromatin activity during mammalian oogenesis or early embryogenesis.
我们使用一种能识别体细胞中存在的组蛋白H1亚型的抗体，检测了牛卵母细胞和植入前胚胎中体细胞组蛋白H1的分布。在减数分裂中期II的染色体上或早期卵裂期胚胎的细胞核中均未检测到免疫反应性H1。在大多数胚胎中，受精后第四至第六个细胞周期期间，免疫反应性H1组装到胚胎染色质上。然而，当胚胎在第四个细胞周期早期开始在α-鹅膏蕈碱存在的情况下培养时，未检测到免疫反应性体细胞组蛋白H1。这些结果表明，组蛋白H1的体细胞亚型以发育调控的方式组装到胚胎染色质上，这需要胚胎转录。当在第四个细胞周期早期存在时，DNA复制抑制剂阿非迪霉素也抑制了体细胞组蛋白H1组装到染色质上。有人提出，由于增殖细胞中大部分组蛋白基因表达发生在DNA复制期间，在进入S期之前或之后不久被阻断的胚胎中，编码免疫反应性H1的基因表达受到抑制。这些关于牛体细胞组蛋白H1组装到染色质上的控制的发现与在小鼠中发现的结果非常相似。这种进化保守性表明，染色质的体细胞组蛋白H1补充可能在哺乳动物卵子发生或早期胚胎发生过程中调节染色质活性的关键方面。
