大鼠衰老过程中肝细胞核及染色质的体外转录活性

Age-related Changes in RNA Synthesis in Isolated Rat Liver Nuclei and Chromatins

用同位素掺入法研究不同年龄大鼠的肝细胞核及染色质体外转录活性,所得结果表明:(1)老年大鼠肝细胞核的转录起始能力较断乳鼠及青年鼠分别下降68％及56％。(2)大鼠肝细胞核内与染色质结合的RNA聚合酶所致的转录活性随增龄呈近似线性下降,而不与染色质结合的RNA聚合酶所致的转录活性随增龄则无变化。(3)老年大鼠肝染色质体外转录活性较断乳鼠及青年鼠分别下降52％及35％。这些结果提示。老年大鼠肝染色质功能的改变可能是转录活性改变的主要原因。

Studies on Incorporation of [γ-32P] ATP, Showed that initiation of RNA synthesis in liver nuclei of rat at the age of 26 months, have decreased about 68% and 56% from the age of 1 and 10 months respectively.By measuring the incorporation of [3H] UMP, RNA synthesis by chromatin-bound RNA polymerase in rat liver nuclei was found to decrease with age, but the RNA synthysis by chromatin unbound RNA-polymerase was not changed.The template activity of chromatin isolated from rat. liver at various ages was compared with the addition of E. coli RNA polymerase. The results showed decrements of about 52% from the age of 1 to 26 months, and 25% from the age of 10 to 26 months.These results suggest that the changing of chromatin template activity is the primary cause of change in RNA synthesis with age.