Santi S, Rubbini S, Cinti C, Squarzoni S, Matteucci A, Caramelli E, Guidotti L, Maraldi N M
Istituto di Citomorfologia Normale e Patologica CNR, Bologna, Italy.
Biol Cell. 1994;81(1):47-57. doi: 10.1016/0248-4900(94)90054-x.
In the sperm nuclei the DNA is packaged into a highly condensed form and is not organized into nucleosome and solenoid but is bound and stabilized mainly by the protamines that arrange the DNA in an almost crystalline state. As demonstrated for somatic cells, the sperm DNA has been reported to be organized in loop domains attached to the nuclear matrix structures. However, the possible role of the sperm head matrix in maintaining the loop organization in absence of a typical nucleosomal structures has not been fully elucidated. By using in situ nick translation at confocal and electron microscope level, we analyzed the organization of the DNA-protamine complex and its association with the sperm nuclear matrix. The data obtained indicate that the chromatin organization in sperm nuclei is maintained during the sperm condensation by means of interactions with the nuclear matrix at fixed sites. The fine structure of sperm nucleus and of sperm nuclear matrix, investigated on sections and replicas of freeze-fractured specimens, suggests that the lamellar array, observed by freeze-fracturing in the sperm nuclei, could depend on the inner matrix which presents a regular organization of globular structures possibly involved in the maintenance of chromatin domains in highly condensed sperm nuclei also.
在精子细胞核中，DNA被包装成高度浓缩的形式，没有组装成核小体和螺线管，而是主要由鱼精蛋白结合并稳定，鱼精蛋白将DNA排列成几乎结晶的状态。如体细胞所示，据报道精子DNA以附着于核基质结构的环状结构域形式存在。然而，在缺乏典型核小体结构的情况下，精子头部基质在维持环状结构组织方面的可能作用尚未完全阐明。通过在共聚焦和电子显微镜水平上进行原位缺口平移，我们分析了DNA-鱼精蛋白复合物的组织及其与精子核基质的关联。所获得的数据表明，精子细胞核中的染色质组织在精子浓缩过程中通过与固定位点的核基质相互作用得以维持。在冷冻断裂标本的切片和复制品上对精子细胞核和精子核基质的精细结构进行研究，结果表明，通过冷冻断裂在精子细胞核中观察到的层状排列可能依赖于内部基质，该内部基质呈现出球状结构的规则组织，这可能也参与了高度浓缩的精子细胞核中染色质结构域的维持。
