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S期和G2期小鼠受精卵对X射线诱导的染色体损伤的辐射敏感性及修复抑制剂的作用

Radiosensitivity and effects of repair inhibitors for X-ray-induced chromosomal damage in mouse zygotes in S and G2 phases.

作者信息

Matsuda Y, Tobari I

机构信息

Division of Genetics, National Institute of Radiological Sciences, Chiba, Japan.

出版信息

Int J Radiat Biol. 1995 Dec;68(6):615-23. doi: 10.1080/09553009514551621.

Abstract

The potentiation effects of arabinofuranosyl cytosine (ara-C), hydroxyurea, 3-aminobenzamide, and caffeine on the yield of chromosome aberrations were examined at the first-cleavage metaphase in mouse zygotes irradiated with X-rays in S and G2 phases (7.5 and 12 h after insemination respectively) in vitro. Potentiation effects were found in both S and G2 for all chemicals except ara-C. Caffeine completely released G2 arrest, which was not overcome by any other chemicals, and enhanced chromosome aberrations most effectively. Caffeine enhanced chromosome aberrations more in G2 irradiation than in S irradiation, and the frequency of chromatid-type aberrations was remarkably enhanced in G2 irradiation. The results in this study demonstrated an existence of two types of caffeine effects in the mouse zygotes irradiated in S and G2; a cancellation of G2 arrest and direct inhibition of DNA repair pathways. The chromosomal damage induced in G2 was effectively repaired by a repair pathway, which is affected by caffeine, on the other hand, the progression of cell cycle, not repair inhibition, was a major factor of caffeine effect on the yield of chromosome aberrations in S irradiation.

摘要

在体外对处于S期和G2期(分别在授精后7.5小时和12小时)接受X射线照射的小鼠受精卵,于第一次卵裂中期检测了阿糖胞苷(ara-C)、羟基脲、3-氨基苯甲酰胺和咖啡因对染色体畸变率的增效作用。除ara-C外,所有化学物质在S期和G2期均发现有增效作用。咖啡因完全解除了G2期阻滞,这是其他任何化学物质都无法克服的,并且最有效地增强了染色体畸变。咖啡因在G2期照射中比在S期照射中更能增强染色体畸变,并且在G2期照射中染色单体型畸变的频率显著增加。本研究结果表明,在S期和G2期照射的小鼠受精卵中存在两种咖啡因效应;解除G2期阻滞和直接抑制DNA修复途径。另一方面,G2期诱导的染色体损伤通过一种受咖啡因影响的修复途径得到有效修复,而在S期照射中,细胞周期的进展而非修复抑制是咖啡因对染色体畸变率产生影响的主要因素。

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