衰老过程中大白鼠脾细胞的DNA单链断裂与重接能力的变化

 DNA被紫外线损伤后,由DNA切除修复酶切除嘧啶二聚体,随之以另一条正常的DNA链为模板修复合成DNA片段,最后由DNA连接酶将新合成的DNA片与原有的DNA链连接。本文用荧光法测定DNA修复过程中DNA单链的断裂及重接能力与衰老的关系。结果表明,不同年龄大鼠脾细胞均具有修复DNA单链断裂的能力,DNA单链断裂重接的能力与年龄有相关性,断乳鼠及青年鼠的脾细胞当保温至30min时,即开始了DNA链的重接,保温90min后则恢复到原有水平;而老年鼠脾细胞保温至90min时才开始DNA链的重接,保温150min,尚未恢复到原有水平。还发现,断乳鼠及老年鼠脾细胞的单链DNA含量高于青年鼠。

Studies of DNA Single Strand Breaks and Rejoining After UV Irradiation of Rat Spleen Cells During Aging

After UV irradiation, damaged DNA repaired through excision repair systems including the processes of DNA nicking near damaged site, DNA repair replication and DNA ligation.We have studied the relationship between DNA repair efficiency and aging by fluorescence assay for detecting DNA single strand breaks.The result showed that rejoining of single strand breaks occurred after 30 minutes incubation and was completed after 90 minutes incubation in weaning and young rat spleen cells, while 150 minutes incubation were needed for complete rejoining in old rat pleen cells.The largest maximum amount of single strand breaks was shown in the process of DNA repair of old rat spleen cells rather than the other cells.The analysis of single strand DNA S1 nuclease showed that weaning and old rat spleen cells contained 4.4% and 4.2% single strand DNA, higher than that of young rat spleen cells, which is 1.7%.