Bettega D, Calzolari P, Costa A, Chiorda G N, Tallone L
Dipartimento di Fisica dell'Università degli Studi, Milan, Italy.
Radiat Res. 1995 Jun;142(3):276-80.
Oncogenic transformation of synchronized C3H 10T1/2 cells was determined after exposure to 4.3 MeV alpha particles (LET = 101 keV/microns). Two synchronization techniques were tested using basic and modified protocols: one based on the release of cells from contact inhibition and the second on the mitotic shake-off method. Progression of cells through the cycle was followed as a function of time by flow cytometric analysis, DNA labeling for passage through S phase, the growth curve for the cell number and mitotic index measurements. The conclusion is that, although the release of cells from confluence provides higher yields of synchronized cells, mitotic shake-off proved to be the best way of collecting a synchronized population of minimally perturbed cells. Cells synchronized by mitotic shake-off were irradiated with 0.30 Gy in the interval between 2 and 10 h corresponding to G1 and early S phases. For comparison asynchronous populations were irradiated in parallel. Oncogenic transformation frequency, corrected for background, in mid-G1 phase was (18 +/- 4) x 10(-5) (average values of frequencies at 4 and 6 h) compared with the value of (8 +/- 4) x 10(-5) for the asynchronous population. While these data are suggestive of a trend toward a slightly increased sensitivity in mid-G1 phase, it is not statistically significant. The surviving fraction is constant in G1 phase.
在将同步化的C3H 10T1/2细胞暴露于4.3 MeV的α粒子（传能线密度=101 keV/微米）后，测定其致癌转化情况。使用基础方案和改良方案测试了两种同步化技术：一种基于接触抑制解除后细胞的释放，另一种基于有丝分裂抖落法。通过流式细胞术分析、用于检测S期进程的DNA标记、细胞数量的生长曲线以及有丝分裂指数测量，跟踪细胞在细胞周期中的进程随时间的变化。结论是，尽管接触抑制解除后细胞释放可提供更高产量的同步化细胞，但有丝分裂抖落被证明是收集受干扰最小的同步化细胞群体的最佳方法。通过有丝分裂抖落同步化的细胞在对应于G1期和S期早期的2至10小时间隔内接受0.30 Gy的照射。作为比较，异步群体同时接受照射。经背景校正后，G1中期的致癌转化频率为(18±4)×10⁻⁵（4小时和6小时频率的平均值），而异步群体的值为(8±4)×10⁻⁵。虽然这些数据表明在G1中期有敏感性略有增加的趋势，但在统计学上并不显著。G1期的存活分数是恒定的。
