Haaf T, Ward D C
Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06520-8005, USA.
Exp Cell Res. 1995 Aug;219(2):604-11. doi: 10.1006/excr.1995.1270.
The higher order organization of chromosomes in human and mouse sperm-cell nuclei has been visualized by fluorescence in situ hybridization. In mouse testicular sperm, centromeres form several linear higher order structures that are attached to a heterochromatic chromocenter at the center of the nucleus. Telomeres of the acrocentric mouse chromosomes are associated with either the heterochromatic center or the nuclear membrane. Whole chromosome domains are arranged parallel to the heterochromatic chromocenter and occasionally wrapped around it. We propose that constitutive heterochromatin serves as the nucleation point for a cell-type-specific organization of mouse sperm chromatin. In human mature sperm, individual chromosomes also appear as elongated territories. When human sperm nuclei are lysed with high salt and detergent, the normally condensed sperm chromatin unravels into linear arrays that exhibit a discrete nodular substructure (of < 300 nm diameter). These beads may represent a basic packaging unit of sperm chromatin. Larger superbead-like structures are also seen along the extended chromatin fibers and these could contain multiples of the basic packaging unit. These observations indicate that mammalian sperm nuclei have a highly defined nuclear architecture. The implications of an ordered organization of DNA in sperm are unknown, but it is possible that functional compartmentalization of the sperm-cell nucleus influences the initiation and regulation of paternal gene activity in the early embryo.
通过荧光原位杂交技术，已观察到人类和小鼠精子细胞核中染色体的高级组织形式。在小鼠睾丸精子中，着丝粒形成了几个线性的高级结构，这些结构附着于细胞核中心的一个异染色质染色中心。近端着丝粒小鼠染色体的端粒与异染色质中心或核膜相关联。整条染色体区域与异染色质染色中心平行排列，偶尔会围绕其缠绕。我们提出，组成型异染色质作为小鼠精子染色质细胞类型特异性组织的成核点。在人类成熟精子中，单个染色体也呈现为拉长的区域。当用高盐和去污剂裂解人类精子细胞核时，通常浓缩的精子染色质会解聚成线性阵列，呈现出离散的结节状亚结构（直径<300 nm）。这些珠子可能代表精子染色质的基本包装单位。在延伸的染色质纤维上也可见到更大的类超级珠子结构，这些结构可能包含多个基本包装单位。这些观察结果表明，哺乳动物精子细胞核具有高度明确的核结构。精子中DNA有序组织的意义尚不清楚，但精子细胞核的功能分区可能会影响早期胚胎中父本基因活性的起始和调控。
