Clausen O P
Department of Pathology, National Hospital of Norway, Oslo.
Cytometry. 1987 Nov;8(6):612-7. doi: 10.1002/cyto.990080613.
DNA synthesis kinetics of P388 leukemic cells growing in ascites form in BDF1 hybrid mice were investigated during the periods of exponential growth and growth restriction. Incorporation of tritiated thymidine, and in some instances tritiated uridine, was studied by autoradiography in cells sorted from S-phase fractions during DNA flow cytometry. During exponential growth continuous labeling with tritiated thymidine indicated a growth fraction of unity, whereas the growth fraction was about 30% during growth restriction. At this growth phase the majority of cells with S phase DNA content remained unlabeled after pulse labeling with tritiated thymidine or uridine, indicating that both the "salvage" and the "de novo" DNA synthesis pathways were blocked in most S-phase cells. After pulse labeling with tritiated thymidine the DNA synthesis rate pattern was investigated by sorting of consecutive fractions of cells throughout the S phase followed by quantitative autoradiography. With exception of a reduced rate in the middle of S phase, the DNA synthesis rate increased as the cells progressed through S phase during exponential growth. In contrast, the DNA synthesis rate pattern had a relative peak in the middle of S phase during growth restriction, which is otherwise characterized by a low mean DNA synthesis rate.
研究了BDF1杂交小鼠腹水中生长的P388白血病细胞在指数生长期和生长受限期的DNA合成动力学。在DNA流式细胞术中，通过放射自显影研究了从S期组分中分选出来的细胞中氚标记胸腺嘧啶核苷的掺入情况，在某些情况下还研究了氚标记尿苷的掺入情况。在指数生长期，用氚标记胸腺嘧啶核苷进行连续标记表明生长分数为1，而在生长受限期生长分数约为30%。在此生长阶段，用氚标记胸腺嘧啶核苷或尿苷进行脉冲标记后，大多数具有S期DNA含量的细胞仍未被标记，这表明大多数S期细胞中的“补救”和“从头”DNA合成途径均被阻断。用氚标记胸腺嘧啶核苷进行脉冲标记后，通过对整个S期连续的细胞组分进行分选，然后进行定量放射自显影，研究了DNA合成速率模式。在指数生长期，随着细胞在S期的进展，除了S期中间速率降低外，DNA合成速率增加。相反，在生长受限期，DNA合成速率模式在S期中间有一个相对峰值，而生长受限期的特征是平均DNA合成速率较低。
