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目的 观察老年大鼠下丘脑和垂体神经细胞核染色质的构象特征。 方法 选用微球菌核酸酶 (MCN)和脱氧核糖核酸酶I(DNaseI)作为染色质结构识别探针 ,经琼脂糖和聚丙烯酰胺凝胶电泳 (PAGE) ,显示老年大鼠和青年大鼠下丘脑、垂体神经细胞核染色质的结构变化。 结果 老年大鼠下丘脑、垂体染色质核小体重复DNA长度分别为 (190± 7)bp和 (171± 8)bp ,而青年大鼠分别为(193± 9)bp和 (170± 5 )bp ;DNaseI酶解DNA产物PAGE显示各年龄组染色质DNA均存在 10bp间隔重复结构和相同的电泳区带分布特征 ;DNaseI染色质降解率老年大鼠明显低于青年大鼠。 结论 (1)老年大鼠和青年大鼠下丘脑、垂体染色质核小体重复DNA长度未发现随龄变化特征 ,但呈明显组织差异 ;(2 )染色质DNA均以B型双股螺旋构象形式存在 ;(3)老年大鼠染色质DNA抗DNaseI酶解能力增强。
Objective To observe the conformational features of nuclear chromatin in hypothalamus and pituitary neurons in aged rats. Methods Using micrococcal nuclease (MCN) and DNase I as chromatin structure recognition probes, agarose and polyacrylamide gel electrophoresis (PAGE) showed that the hypothalamus of aged rats and young rats , Structural changes of pituitary nerve cell nuclear chromatin. Results The lengths of repetitive DNA in hypothalamus and pituitary gland were (190 ± 7) bp and (171 ± 8) bp respectively in young rats, while those in young rats were (193 ± 9) bp and (170 ± 5) bp; DNaseI digested DNA product PAGE showed that there was a 10 bp repeat structure and the same electrophoretic zone distribution in each age group. The degradation rate of DNase I in aged rats was significantly lower than that in young rats. Conclusions (1) There was no significant difference in the length of the repetitive DNA of hypothalamus and pituitary gland nucleus in aged rats and young rats, but the difference was significant. (2) The chromatin DNA was expressed in B-type double helical conformation Form; (3) chromatin DNA in elderly rats anti DNaseI enhanced enzymatic activity.