Ward W S, Coffey D S
Division of Urology, Robert Wood Johnson Medical School, New Brunswick, New Jersey 08903.
Biol Reprod. 1991 Apr;44(4):569-74. doi: 10.1095/biolreprod44.4.569.
Mammalian sperm DNA is the most tightly compacted eukaryotic DNA, being at least sixfold more highly condensed than the DNA in mitotic chromosomes. To achieve this high degree of packaging, sperm DNA interacts with protamines to form linear, side-by-side arrays of chromatin. This differs markedly from the bulkier DNA packaging of somatic cell nuclei and mitotic chromosomes, in which the DNA is coiled around histone octamers to form nucleosomes. The overall organization of mammalian sperm DNA, however, resembles that of somatic cells in that both the linear arrays of sperm chromatin and the 30-nm solenoid filaments of somatic cell chromatin are organized into loop domains attached at their bases to a nuclear matrix. In addition to the sperm nuclear matrix, sperm nuclei contain a unique structure termed the sperm nuclear annulus to which the entire complement of DNA appears to be anchored when the nuclear matrix is disrupted during decondensation. In somatic cells, proper function of DNA is dependent upon the structural organization of the DNA by the nuclear matrix, and the structural organization of sperm DNA is likely to be just as vital to the proper functioning of the spermatozoa.
哺乳动物精子DNA是压缩程度最高的真核生物DNA，其浓缩程度比有丝分裂染色体中的DNA至少高六倍。为了实现这种高度的包装，精子DNA与鱼精蛋白相互作用，形成线性、并排排列的染色质阵列。这与体细胞细胞核和有丝分裂染色体中更为庞大的DNA包装明显不同，在体细胞细胞核和有丝分裂染色体中，DNA围绕组蛋白八聚体盘绕形成核小体。然而，哺乳动物精子DNA的整体组织与体细胞的相似，因为精子染色质的线性阵列和体细胞染色质的30纳米螺线管细丝都被组织成环结构域，其基部附着于核基质。除了精子核基质外，精子细胞核还含有一种独特的结构，称为精子核环，当在去浓缩过程中核基质被破坏时，整个DNA互补序列似乎都锚定在精子核环上。在体细胞中，DNA的正常功能依赖于核基质对DNA的结构组织，而精子DNA的结构组织对于精子的正常功能可能同样至关重要。
