Somma S, Polsinelli M
J Bacteriol. 1970 Mar;101(3):851-5. doi: 10.1128/jb.101.3.851-855.1970.
The relationships among deoxyribonucleic acid (DNA) uptake, transformation, and autoradiographic labeling were investigated. It is shown that: (i) autoradiography is a good method for measuring the total fraction of competent cells able to incorporate transforming DNA; in our best experiment that fraction was 11.5%. (ii) Computation of the fraction of competent cells in a culture of Bacillus subtilis, by comparing the frequencies of single and double transformants for two unlinked markers, gives values which are somewhat different from those obtained by auto-radiography. (iii) On the average, a competent cell of B. subtilis irreversibly takes up from 0.9 x 10(-10) to 1.4 x 10(-10) mug of DNA; this amount represents about 1/55 to 1/35 of the bacterial chromosome weighing 5 x 10(-9) mug, and corresponds to three to six DNA molecules having a molecular weight of 1.6 x 10(7).
对脱氧核糖核酸(DNA)摄取、转化及放射自显影标记之间的关系进行了研究。结果表明:(i)放射自显影术是测定能够摄取转化DNA的感受态细胞总比例的一种好方法;在我们最佳的实验中,该比例为11.5%。(ii)通过比较两个不连锁标记的单转化体和双转化体的频率来计算枯草芽孢杆菌培养物中感受态细胞的比例,所得值与通过放射自显影获得的值略有不同。(iii)平均而言,枯草芽孢杆菌的一个感受态细胞不可逆地摄取0.9×10⁻¹⁰至1.4×10⁻¹⁰微克的DNA;该量约占重5×10⁻⁹微克的细菌染色体的1/55至1/35,相当于三至六个分子量为1.6×10⁷的DNA分子。