Lönn U
J Cell Sci. 1980 Dec;46:387-97. doi: 10.1242/jcs.46.1.387.
The size of the DNA replication units in salivary gland polytene chromosomes of Chironomus arvac at 2 developmental stages (red-head and late 4th instar) was investigated. The 2 developmental stages differ with respect to intensity of DNA replication with much lower values at the red-head stage. Also the level of polytenization is lower at the red-head stage. The size of the replication units was measured by determining the size of double-stranded DNA fragments released from active replication units during the cell lysis. At both stages it is possible to release from the polytene chromosome a double-stranded DNA fragment of similar size. This indicates that there is no or very little difference in size of active replication units in the same tissue at the 2 developmental stages.
研究了摇蚊在两个发育阶段（红头期和四龄后期）唾液腺多线染色体中DNA复制单位的大小。这两个发育阶段在DNA复制强度方面存在差异，红头期的DNA复制强度要低得多。而且红头期的多线化水平也较低。通过测定细胞裂解过程中从活跃复制单位释放的双链DNA片段的大小来测量复制单位的大小。在两个阶段都有可能从多线染色体中释放出大小相似的双链DNA片段。这表明在同一组织的两个发育阶段，活跃复制单位的大小没有差异或差异非常小。
