Humphrey R M, Brinkley B R
J Cell Biol. 1969 Sep;42(3):745-53. doi: 10.1083/jcb.42.3.745.
The fine structure of radiation-induced chromosomal aberrations in Potorous tridactylis (rat kangaroo) cells was examined in situ by electron microscopy. The observations on the structure of terminal deletions (acentric fragments), anaphase bridges and "gaps," sidearm bridges, and specialized regions, such as the nucleolus organizer, are discussed in detail. Conclusions based on these observations are the following: (a) damage is physically expressed only at anaphase; (b) a gap region is composed of two subunits, each of which is about 800-1000 A in diameter and may correspond to a half-chromatid structure; (c) the ends of acentric fragments are structurally similar to normal chromosome ends, except where the break occurs in a specific region such as the secondary constriction; (d) at metaphase the fragment and the main portion of the chromosome move as a single unit to the equator, and the two units are disconnected only at the onset of anaphase; (e) sidearm bridges appear to be exchanges, involving a subchromatid unit. The interpretation of this evidence is consistent with the hypothesis that the chromosome is a multistranded structure.
通过电子显微镜对辐射诱导的三趾袋狸（鼠袋鼠）细胞中的染色体畸变精细结构进行了原位检查。详细讨论了对末端缺失（无着丝粒片段）、后期桥和“间隙”、侧臂桥以及特殊区域（如核仁组织区）结构的观察结果。基于这些观察得出的结论如下：(a) 损伤仅在后期以物理方式表现出来；(b) 间隙区域由两个亚基组成，每个亚基直径约为800 - 1000埃，可能对应于半染色单体结构；(c) 无着丝粒片段的末端在结构上与正常染色体末端相似，除非断裂发生在特定区域，如次缢痕；(d) 在中期，片段和染色体的主要部分作为一个整体移动到赤道，这两个单元仅在后期开始时断开连接；(e) 侧臂桥似乎是涉及亚染色单体单元的交换。对这些证据的解释与染色体是多链结构的假设一致。
