Clark R W, Tseng P O, Lechuga J M
Exp Cell Res. 1987 Apr;169(2):296-310. doi: 10.1016/0014-4827(87)90192-3.
When isolated Chinese hamster cells (CHO) metaphase chromosomes are treated with nuclease Bal-31, the DNA is reduced to a size class that is resistant to further degradation. This size class resembles the distribution of replicon sizes in this particular cell line in both average size and size range. Tests based on molecular weight (MW) analysis were devised to locate the origin of replication within the Bal-31 segments. The evidence indicates that replication origins are positioned at or near the center of these segments. The tests were made possible by the additional discovery that BrdU-substituted DNA is highly susceptible to Bal-31 nuclease attack while still contained in the isolated metaphase chromosome.
当用核酸酶Bal-31处理分离的中国仓鼠细胞（CHO）中期染色体时，DNA被降解至对进一步降解具有抗性的大小类别。该大小类别在平均大小和大小范围方面都类似于该特定细胞系中复制子大小的分布。设计了基于分子量（MW）分析的测试来定位Bal-31片段内的复制起点。证据表明复制起点位于这些片段的中心或其附近。由于另外发现BrdU取代的DNA在仍包含于分离的中期染色体中时对Bal-31核酸酶攻击高度敏感，这些测试才得以进行。
