Keppel F
J Mol Biol. 1986 Jan 5;187(1):15-21. doi: 10.1016/0022-2836(86)90402-x.
Nuclear matrices were prepared from HeLa nuclei in high or low-salt buffers. After digestion with restriction enzymes, the DNA associated with the nuclear matrix was analysed for its content of ribosomal DNA sequences (rDNA). In both salt conditions, the entire rDNA repeat unit was found to be enriched in the matrix DNA. No enrichment, however, was detected in the absence of rRNA transcription either due to treatment with actinomycin D or when cells arrested in the G0 stage were used to prepare matrices. rDNA was found to be linked to chromosomal scaffolding structures when similar experiments were performed on chromosomes. Moreover, a gradient of enrichment along the rDNA repeat unit was observed, in which the promoter-containing portion was the most highly enriched. I conclude from these experiments that the tandem repeats of rDNA are not randomly associated with matrix or scaffold structure but are probably attached at transcription complexes.
核基质是在高盐或低盐缓冲液中由HeLa细胞核制备而来。用限制性内切酶消化后，分析与核基质相关的DNA中核糖体DNA序列（rDNA）的含量。在两种盐浓度条件下，均发现整个rDNA重复单元在基质DNA中富集。然而，无论是用放线菌素D处理导致rRNA转录缺失，还是使用停滞在G0期的细胞制备基质，均未检测到富集现象。当对染色体进行类似实验时，发现rDNA与染色体支架结构相连。此外，沿rDNA重复单元观察到一个富集梯度，其中含启动子的部分富集程度最高。我从这些实验得出结论，rDNA的串联重复并非随机与基质或支架结构相关联，而是可能附着于转录复合物上。
