Chan G L, Little J B
Int J Radiat Biol Relat Stud Phys Chem Med. 1979 Feb;35(2):101-10. doi: 10.1080/09553007914550121.
Clonogenic survival was measured in plateau-phase cultures of the 10T1/2 mouse cell line exposed to 254 nm ultra-violet light. The survival curve was found to be biphasic, Do for the two components being 37 and 1191 erg/mm2 respectively. This extreme resistance at higher doses can only be partly accounted for by the increased cytoplasmic absorption of U.V.L. due to an increased thickness of plateau-phase cells. When the cultures were held for 24 hours in plateau phase in conditioned medium after irradiation, recovery yielding a 1.4-fold enhancement of survival was found at higher doses. This recovery process was inhibited by neither caffeine nor cycloheximide. When caffeine was given for 48 hours after sub-culture, the effect on survival was also negligible. We propose that this plateau-phase recovery process is associated with excision repair of DNA adducts induced by U.V.L. Delayed sub-culturing favours the excision mode of repair and renders the post-replication mode less necessary.
在暴露于254nm紫外线的10T1/2小鼠细胞系的平台期培养物中测量克隆形成存活率。发现存活曲线是双相的，两个组分的Do分别为37和1191erg/mm2。在较高剂量下这种极端抗性只能部分归因于由于平台期细胞厚度增加导致的紫外线细胞质吸收增加。当培养物在照射后在条件培养基中在平台期保持24小时时，发现在较高剂量下存活提高了1.4倍的恢复。这种恢复过程既不受咖啡因也不受环己酰亚胺的抑制。当在传代培养后给予咖啡因48小时时，对存活的影响也可以忽略不计。我们提出这种平台期恢复过程与紫外线诱导的DNA加合物的切除修复有关。延迟传代培养有利于切除修复模式并减少复制后模式的必要性。
