Gosden J R, Irving M I, Bishop J O
Biochem J. 1971 Jan;121(1):109-16. doi: 10.1042/bj1210109.
A method is described for measuring the proportion of galactose-specific mRNA (gal-mRNA) in the total RNA extracted from pulse-labelled cells of Escherichia coli K12, by DNA-RNA hybridization with DNA prepared from bacteriophage lambdadg. RNA from wild-type E. coli was compared with RNA from a homogenote carrying the gal operon both in the chromosome and in a substituted sex-factor, and with RNA from a deletion strain that carried the galactose operon only in the exogenote. In each case the cultures were induced with fucose. Under these conditions the amount of gal-mRNA was found to be proportional to the content of galactokinase in the different cultures, and to the gene frequency. The amounts of gal-mRNA in an O(c) mutant and an R(-) mutant were also proportional to the observed contents of galactokinase. In cultures repressed for the enzymes of the galactose operon with thiomethylgalactoside, the content of gal-mRNA was higher than expected from the content of galactokinase. Possible explanations of this finding are discussed.
本文描述了一种通过与噬菌体λdg制备的DNA进行DNA-RNA杂交，来测量从脉冲标记的大肠杆菌K12细胞中提取的总RNA中半乳糖特异性mRNA（gal-mRNA）比例的方法。将野生型大肠杆菌的RNA与在染色体和替代性因子中均携带半乳糖操纵子的同基因体的RNA，以及仅在外基因子中携带半乳糖操纵子的缺失菌株的RNA进行了比较。在每种情况下，培养物均用岩藻糖诱导。在这些条件下，发现gal-mRNA的量与不同培养物中半乳糖激酶的含量以及基因频率成正比。O(c)突变体和R(-)突变体中gal-mRNA的量也与观察到的半乳糖激酶含量成正比。在用硫代甲基半乳糖苷抑制半乳糖操纵子酶的培养物中，gal-mRNA的含量高于根据半乳糖激酶含量预期的水平。本文讨论了这一发现的可能解释。
