Norwood T H, Pendergrass W R, Sprague C A, Martin G M
Proc Natl Acad Sci U S A. 1974 Jun;71(6):2231-5. doi: 10.1073/pnas.71.6.2231.
In heterokaryons between senescent and young diploid fibroblast-like cells, dominance of the former with respect to nuclear DNA synthesis (incorporation of [(3)H]thymidine) was demonstrated. For identification of the respective partners, double-layer autoradiography was used after the old cells were labeled with [(3)H]methionine and the young cells were labeled with [(14)C]thymidine. Synchrony of nuclear labeling (i.e., all nuclei in a cell labeled with [(3)H]thymidine) was observed in the majority of di- and polykaryons during the second and third of three 24-hr periods of labeling with [(3)H]thymidine. The results are compatible with either terminal differentiation or error theories of clonal senescence.
在衰老的二倍体成纤维样细胞与年轻的二倍体成纤维样细胞之间形成的异核体中，已证明前者在核DNA合成（[³H]胸苷掺入）方面占主导地位。为了识别各自的细胞，在用[³H]甲硫氨酸标记老细胞并用[¹⁴C]胸苷标记年轻细胞后，采用了双层放射自显影术。在用[³H]胸苷进行三个24小时标记期的第二个和第三个时期，在大多数双核体和多核体中观察到核标记同步（即细胞中的所有细胞核都用[³H]胸苷标记）。这些结果与克隆衰老的终末分化理论或错误理论均相符。
