Bombik B M, Baserga R
Proc Natl Acad Sci U S A. 1974 May;71(5):2038-42. doi: 10.1073/pnas.71.5.2038.
Nuclear monolayers of WI-38 cells prepared by the method of Tsai and Green were used to determine RNA synthesis in isolated nuclei in situ. In nuclear monolayers, incorporation of [(3)H]UTP into RNA is dependent on the presence of the other three nucleotide triphosphate and is abolished by actinomycin D. The extent of RNA synthesis under these conditions was measured in density-inhibited WI-38 human diploid fibroblasts at various intervals after cell proliferation was stimulated by a change of medium.RNA synthesis increases 15 min after the nutritional change and reaches a peak at 18 hr, which is also the peak of DNA synthesis. Thereafter RNA synthesis declines. Essentially similar results are obtained whether the endogenous RNA polymerase or a bacterial polymerase is used. Replacement of the stimulating medium by conditioned medium stops the increase in RNA synthesis that occurs in cultures subject to continuous stimulation. Finally, RNA synthesis in nuclear monolayers, using the endogenous RNA polymerase, occurs by chain elongation only, while re-initiation occurs with the bacterial RNA polymerase.
采用蔡和格林的方法制备的WI-38细胞核单层，用于原位测定分离细胞核中的RNA合成。在细胞核单层中，[（3）H]UTP掺入RNA依赖于其他三种三磷酸核苷酸的存在，并且放线菌素D可将其抑制。在通过更换培养基刺激细胞增殖后的不同时间间隔，测量了密度抑制的WI-38人二倍体成纤维细胞在这些条件下的RNA合成程度。营养变化后15分钟RNA合成增加，并在18小时达到峰值，这也是DNA合成的峰值。此后RNA合成下降。无论使用内源性RNA聚合酶还是细菌聚合酶，都能得到基本相似的结果。用条件培养基替代刺激培养基可阻止在持续刺激的培养物中发生的RNA合成增加。最后，使用内源性RNA聚合酶时，细胞核单层中的RNA合成仅通过链延伸发生，而细菌RNA聚合酶则会发生重新起始。
