Zamboni M, Privitera E, Mosna G, Ghidoni A
Dipartimento di Genetica e di Biologia dei Microrganismi, Università di Milano, Italy.
Genetica. 1990;80(3):229-33. doi: 10.1007/BF00137330.
Sister chromatid exchange (SCE) induction by methotrexate (MTX) was analyzed in C3H10T1/2 clone 8 mouse cells and in two MTX-resistant subclones with numerous double minute chromosomes (DM) present in the majority of cells. Significantly higher SCE levels were found, as expected, in sensitive cells after treatments with 10(-2) or 10(-5) M MTX but not in resistant cells permanently growing in the presence of a high concentration of MTX (2 x 10(-3) M) and characterized by a markedly lower cell cycle replication index (R.I.), i.e. in conditions that are known to otherwise favour SCE induction. These observations suggest, for the MTX-resistant cells under study, the existence of conditions limiting SCE formation.
在C3H10T1/2克隆8小鼠细胞以及两个大多数细胞中存在大量双微体染色体（DM）的甲氨蝶呤（MTX）抗性亚克隆中，分析了MTX诱导的姐妹染色单体交换（SCE）情况。正如预期的那样，在用10⁻²或10⁻⁵ M MTX处理后，敏感细胞中的SCE水平显著更高，但在高浓度MTX（2×10⁻³ M）存在下永久生长且细胞周期复制指数（R.I.）明显较低的抗性细胞中并非如此，即在已知其他情况下有利于SCE诱导的条件下也并非如此。这些观察结果表明，对于所研究的MTX抗性细胞，存在限制SCE形成的条件。
