González-Fernández A, Hernández P, López-Sáez J F
Mutat Res. 1985 Apr;149(2):275-81. doi: 10.1016/0027-5107(85)90034-x.
Proliferating plant cells treated during the late S period with 5-aminouracil (AU), give the typical response that DNA-damaging agents induce, characterized by: an important mitotic delay, and a potentiation of the chromosome damage by caffeine post-treatment. The study of labelled prophases, after a tritiated thymidine pulse, allowed evaluation of the mitotic delay induced by AU as well as its reversion by caffeine, while chromosome damage was estimated by the percentage of anaphases and telophases showing chromosomal aberrations. Post-treatment with adenosine alone has shown no effect on mitotic delay or chromosomal damage. However, when cells after AU were incubated in caffeine plus adenosine, the chromosome damage potentiation was abolished without affecting the caffeine action on mitotic delay. As a consequence, we postulate that caffeine could have two effects on G2 cells with damaged DNA: the first, to cancel their mitotic delay and the second to inhibit some DNA-repair pathway(s). Only this last effect could be reversed by adenosine.
在S期后期用5-氨基尿嘧啶（AU）处理的增殖植物细胞，会产生DNA损伤剂诱导的典型反应，其特征为：显著的有丝分裂延迟，以及咖啡因后处理对染色体损伤的增强作用。在氚标记胸腺嘧啶脉冲后对标记前期进行研究，能够评估AU诱导的有丝分裂延迟以及咖啡因对其的逆转作用，而染色体损伤则通过显示染色体畸变的后期和末期的百分比来估计。单独用腺苷进行后处理对有丝分裂延迟或染色体损伤没有影响。然而，当用AU处理后的细胞在咖啡因加腺苷中孵育时，染色体损伤增强作用被消除，而不影响咖啡因对有丝分裂延迟的作用。因此，我们推测咖啡因对DNA受损的G2期细胞可能有两种作用：第一种是消除它们的有丝分裂延迟，第二种是抑制某些DNA修复途径。只有最后这种作用可被腺苷逆转。
