Hud N V, Allen M J, Downing K H, Lee J, Balhorn R
Biology and Biotechnology Research Program, Lawrence Livermore National Laboratory, Livermore, CA 94550.
Biochem Biophys Res Commun. 1993 Jun 30;193(3):1347-54. doi: 10.1006/bbrc.1993.1773.
DNA is packaged within the sperm cell nuclei of many vertebrates and all mammals in a highly condensed state by small basic proteins (protamines). Despite continuous investigation for nearly half a century, the actual packing arrangement of the DNA has remained unresolved. Atomic force and electron microscopy studies described in this report provide evidence that the fundamental packing unit for sperm DNA is a toroidal structure, 900A in outside diameter with a 150A diameter hole, which contains up to 60kb of DNA. Although the results presented here are based primarily upon investigations of mammalian sperm cells, they are expected to be valid for all sperm cells which utilize protamines to package DNA.
在许多脊椎动物和所有哺乳动物的精子细胞核内，DNA通过小的碱性蛋白质（鱼精蛋白）以高度浓缩的状态存在。尽管近半个世纪以来一直在持续研究，但DNA的实际包装排列仍未得到解决。本报告中描述的原子力显微镜和电子显微镜研究提供了证据，表明精子DNA的基本包装单元是一种环形结构，外径为900埃，有一个直径150埃的孔，其中包含多达60kb的DNA。尽管此处呈现的结果主要基于对哺乳动物精子细胞的研究，但预计它们对所有利用鱼精蛋白包装DNA的精子细胞都是有效的。
