The majority of histones are replaced by protamines during spermatogenesis, but small amounts are retained in mammalian spermatozoa. Since nucleosomes in spermatozoa influence epigenetic inheritance, it is important to know how histones are distributed in the sperm genome. Conflicting data, which may result from different conditions used for micrococcal nuclease (MNase) digestion, have been reported: retention of nucleosomes at either gene promoter regions or within distal gene-poor regions. Here, we find that the swim-up sperm used in many studies contain about 10% population of sperm which have not yet completed the histone-to-protamine replacement. We develop a method to purify histone replacement-completed sperm (HRCS) and to completely solubilize histones from cross-linked HRCS without MNase digestion. Our results indicate that histones are retained at specific promoter regions in HRCS. This method allows the study of epigenetic status in mature sperm.

中文翻译：

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组蛋白置换完成的精子中组蛋白结合位点的定位。

在精子发生过程中，大多数组蛋白被鱼精蛋白替代，但少量保留在哺乳动物的精子中。由于精子中的核小体会影响表观遗传，因此了解组蛋白在精子基因组中的分布方式非常重要。已经报道了可能由用于微球菌核酸酶（MNase）消化的不同条件导致的数据冲突：核小体在基因启动子区域或远端基因贫乏区域内的保留。在这里，我们发现许多研究中使用的游动精子包含大约10％的精子，这些精子尚未完成组蛋白到鱼精蛋白的替代。我们开发了一种方法，用于纯化组蛋白置换完成的精子（HRCS），并从交联的HRCS中完全溶解组蛋白，而无需进行MNase消化。我们的结果表明，组蛋白保留在HRCS的特定启动子区域。这种方法可以研究成熟精子的表观遗传状态。