Chakrabarty P K, Chattopadhyay S K, Schneider W C
Cancer Res. 1982 Feb;42(2):421-8.
Administration of thioacetamide to rats for 4 days has been shown previously to increase the activity of liver messenger RNA (mRNA) and to disproportionately increase the activity of albumin mRNA in the wheat germ translation system. We have explored the possibility that administration of thioacetamide quantitatively alters the transcription of rat liver unique DNA. Nucleic acid hybridization between the radioactive rat liver unique DNA and RNA from untreated as well as 4-day thioacetamide-treated rat liver indicates that the normal extent of transcription is not altered by the drug treatment. We also investigated the possibility that thioacetamide treatment increases the level of mRNA in general or of albumin mRNA in particular. Albumin mRNA, which is th most abundantly represented population in rat liver cytoplasmic mRNA, was further enriched by sucrose gradient fractionation of the liver mRNA. Synthesis of complementary DNA (cDNA) and then use of the strategy of limited hybridization yielded the cDNA corresponding to albumin mRNA. Hybridization of the fractionated cDNA with mRNA from untreated livers as well as from livers with increasing days of treatment shows no change in the level of albumin mRNA. The results indicate that drug treatment induces the augmented synthesis of albumin by disproportionately increasing the translational activity of albumin mRNA. Quantitation of gene dosage by comparison of hybridization kinetics of fractionated cDNA and unique [3H]DNA with total rat cellular DNA indicates that there are not more than two copies of the albumin gene present in the rat genome.
先前已表明，给大鼠服用硫代乙酰胺4天可增加肝脏信使核糖核酸（mRNA）的活性，并在麦胚翻译系统中使白蛋白mRNA的活性不成比例地增加。我们探讨了服用硫代乙酰胺定量改变大鼠肝脏特异性DNA转录的可能性。放射性大鼠肝脏特异性DNA与未处理以及经硫代乙酰胺处理4天的大鼠肝脏RNA之间的核酸杂交表明，药物处理不会改变正常的转录程度。我们还研究了硫代乙酰胺处理是否会总体上增加mRNA水平，特别是白蛋白mRNA水平的可能性。白蛋白mRNA是大鼠肝脏细胞质mRNA中含量最丰富的群体，通过肝脏mRNA的蔗糖梯度分级进一步富集。合成互补DNA（cDNA），然后采用有限杂交策略，得到了与白蛋白mRNA对应的cDNA。分级分离的cDNA与未处理肝脏以及处理天数增加的肝脏的mRNA杂交，结果显示白蛋白mRNA水平没有变化。结果表明，药物处理通过不成比例地增加白蛋白mRNA的翻译活性，诱导了白蛋白合成的增加。通过比较分级分离的cDNA和特异性[3H]DNA与大鼠细胞总DNA的杂交动力学来定量基因剂量，结果表明大鼠基因组中白蛋白基因的拷贝数不超过两个。
