Sidransky H, Verney E, Murty C N
J Nutr. 1980 Dec;110(12):2514-26. doi: 10.1093/jn/110.12.2514.
Young rats were force-fed for 3 days a purified diet devoid of threonine and a number of aspects relating to RNA metabolism in the livers were studied. The findings in the livers of rats force-fed the threonine-devoid diet in comparison with those force-fed the complete diet were as follows: a) poly(A)-mRNA was increased in nuclei and in polyribosomes; b) DNA-dependent RNA polymerases I and II activities were increased; c) in vitro release of 14C-orotic acid labeled RNA from nuclei revealed that transport was unchanged and nucleoside triphosphatase activity of nuclear envelopes was unchanged; d) polyribosomes (total, free and membrane-bound) shifted toward heavier aggregation and in vitro 14C-leucine incorporation into protein was increased; e) RNase activities (at pH 5.4, 7.6, 9.5) were essentially unaltered; and f) in vivo 14C-choline incorporation into microsomal membranes was increased. By administering selected inhibitors of RNA and protein synthesis, such as actinomycin D, alpha-amanitin or cycloheximide, prior to killing the rats force-fed the threonine-devoid or complete diet for 3 days, it was demonstrated that the stimulatory effect on hepatic polyribosomes and protein synthesis in the experimental group was dependent upon new synthesis of poly(A)mRNA and of protein.
给幼鼠强制喂食缺乏苏氨酸的纯化饮食3天，并对肝脏中与RNA代谢相关的多个方面进行了研究。将强制喂食缺乏苏氨酸饮食的大鼠肝脏中的发现与强制喂食完全饮食的大鼠肝脏中的发现进行比较，结果如下：a）细胞核和多核糖体中的聚（A）-mRNA增加；b）DNA依赖性RNA聚合酶I和II的活性增加；c）从细胞核中体外释放14C-乳清酸标记的RNA显示转运未改变，核膜的核苷三磷酸酶活性未改变；d）多核糖体（总、游离和膜结合）向更重的聚集体转移，并且体外14C-亮氨酸掺入蛋白质增加；e）RNase活性（在pH 5.4、7.6、9.5下）基本未改变；f）体内14C-胆碱掺入微粒体膜增加。在处死强制喂食缺乏苏氨酸或完全饮食3天的大鼠之前，通过给予选定的RNA和蛋白质合成抑制剂，如放线菌素D、α-鹅膏蕈碱或环己酰亚胺，证明实验组对肝脏多核糖体和蛋白质合成的刺激作用依赖于聚（A）mRNA和蛋白质的新合成。
