Makrides S C, Goldthwaite J
Mech Ageing Dev. 1984 Sep;27(1):111-34. doi: 10.1016/0047-6374(84)90088-5.
The method of Ramsey and Steele [Anal. Biochem., 92 (1979) 305--313] was used to examine the size distribution of membrane-bound and free polyribosomes from the liver of male C57 BL/6 mice over the life span. Optimization of the concentration of Mg2+ and liver cell sap suppressed breakdown by ribonuclease and presumably gave preparations that approximate the integrity of native polyribosome populations. The content of polysomes per unit liver tissue from 7 groups of fed mice aged 10--35 months showed an age-related increase of subunits and monomers (+54%) and dimers-to-pentamers (+76%) in membrane-bound polyribosomes. The dimer-to-pentamer class of free polyribosomes also increased (+52%). Polysomes larger than nonamers showed 13% and 21% decreases that were not statistically significant. Total tissue ribosomes increased 15%, while the membrane-bound/free polyribosome ratio remained nearly constant at about 1.15. In a subsequent study, both 6 h-fasted and fed mice showed decreases (-20% to -33%) in membrane-bound and free polyribosomes larger than nonamers during aging from 15 to 35 months. The dimer-to-pentamer class of free polyribosomes in fed mice increased (+26%), while this class in the other groups underwent increases (+26 to +39%) that were not statistically significant. We conclude that the liver in old mice is not obviously deficient in either quantity or general quality of ribosomes. Old animals do tend to show an increase in small polysomes and a decrease in large polysomes, which is consistent with a reduction in the rate of translation.
采用拉姆齐和斯蒂尔的方法[《分析生物化学》，92(1979)305 - 313]，研究雄性C57 BL/6小鼠肝脏中膜结合型和游离型多核糖体在其整个生命周期内的大小分布。优化镁离子浓度和肝细胞液可抑制核糖核酸酶的降解作用，推测这样得到的制剂接近天然多核糖体群体的完整性。对7组年龄在10 - 35个月的喂食小鼠的单位肝脏组织中的多核糖体含量进行检测，结果显示，膜结合型多核糖体中的亚基和单体含量增加了54%，二聚体至五聚体含量增加了76%，呈现出与年龄相关的变化。游离型多核糖体中二聚体至五聚体类别也增加了52%。大于九聚体的多核糖体含量分别下降了13%和21%，但差异无统计学意义。肝脏组织中的核糖体总量增加了15%，而膜结合型/游离型多核糖体的比例保持在1.15左右基本不变。在随后的一项研究中，在15至35个月龄的衰老过程中，禁食6小时的小鼠和喂食小鼠的膜结合型和游离型且大于九聚体的多核糖体均减少(减少20%至33%)。喂食小鼠中游离型多核糖体的二聚体至五聚体类别增加了26%，而其他组中该类别的增加(增加26%至39%)差异无统计学意义。我们得出结论，老年小鼠肝脏中的核糖体在数量或总体质量上并无明显缺陷。老年动物确实倾向于表现出小多核糖体增加而大多核糖体减少的情况，这与翻译速率降低相一致。
