Nakatsuru Y, Aoki K, Ishikawa T
Department of Experimental Pathology, Cancer Institute, Tokyo, Japan.
Mutat Res. 1989 Jan;219(1):51-6. doi: 10.1016/0921-8734(89)90040-4.
The activity of the DNA repair protein O6-methylguanine DNA methyltransferase (MT) was compared in liver extracts from female ICR and male C57BL/6 mice at various ages (3-130 weeks old). Similar patterns of overall enzyme activity were observed in both strains with O6-MT activity being relatively low in young mice (3 or 8 weeks old). However, the activity significantly increased after adolescence (middle age), thereafter decreasing with old age (over 100 weeks old) to a level equivalent to that found in young mice. In an additional strain difference study, O6-MT activities in liver extracts from 4 strains of mice were compared at 5 and 30 weeks of age. Although a similar age-associated increase of enzyme activity in adolescence was confirmed in all 4 strains investigated, the closed-colony ICR mice differed from the inbred strains in demonstrating significantly higher levels of O6-MT activity in females than in males. However, the same tendency was also observed in a comparison of the sexes in 30-week-old C3H/HeN, C57BL/6 and BALB/c mice.
对不同年龄（3至130周龄）的雌性ICR小鼠和雄性C57BL / 6小鼠肝脏提取物中DNA修复蛋白O6 - 甲基鸟嘌呤DNA甲基转移酶（MT）的活性进行了比较。在两个品系中均观察到总体酶活性的相似模式，O6 - MT活性在幼鼠（3周或8周龄）中相对较低。然而，该活性在青春期（中年）后显著增加，此后随着年龄增长（超过100周龄）而降低至与幼鼠中发现的水平相当。在另一项品系差异研究中，比较了4个品系小鼠在5周龄和30周龄时肝脏提取物中的O6 - MT活性。尽管在所研究的所有4个品系中均证实了青春期酶活性存在类似的年龄相关增加，但封闭群ICR小鼠与近交系不同，其雌性O6 - MT活性水平显著高于雄性。然而，在比较30周龄的C3H / HeN、C57BL / 6和BALB / c小鼠的性别时也观察到了相同的趋势。
