Stahly D P, Srinivasan V R, Halvorson H O
J Bacteriol. 1966 May;91(5):1875-82. doi: 10.1128/jb.91.5.1875-1882.1966.
Stahly, D. P. (University of Illinois, Urbana), V. R. Srinivasan, and H. Orin Halvorson. Effect of 8-azaguanine on the transition from vegetative growth to presporulation in Bacillus cereus. J. Bacteriol. 91:1875-1882. 1966.-The guanine analogue, 8-azaguanine (azaG), was found to inhibit sporulation of Bacillus cereus strain T when added to proliferating cells, but not to inhibit when added after the transition to presporulation. When azaG was added to vegetative cells, the growth rate was reduced, but no immediate bactericidal effect was demonstrated. Azaguanine was shown to be incorporated solely into ribonucleic acid (RNA). All of the natural purine bases and nucleosides were found to prevent azaG inhibition by blocking incorporation of the analogue into the RNA. Addition of a subinhibitory level of C(14)-azaG to proliferating cells resulted in an increase in incorporation paralleling the increase in number of cells. At the time of transition from growth to presporulation, a rapid removal of the azaG label from the cells occurred in the absence of net RNA breakdown. If differentiation was inhibited by increasing the concentration of azaG, then no expulsion took place. Instead, at the end of growth, net incorporation ceased, and a steady-state condition was established in which incorporation equaled breakdown. No azaG degradative enzymes are present in presporulating cells. The possibility is discussed that an increase in the ratio of natural purines to azaG occurred at the time of transition, and that the natural purine derivatives then were reincorporated into RNA preferentially to azaG. The data are consistent with the hypothesis than an increased rate of RNA turnover occurs at the time of transition from vegetative growth to presporulation. Addition of phosphate buffer (pH 7.0, 0.1 m) to azaG-inhibited vegetative cells caused reversal of inhibition, the reversal being accompanied by expulsion of the azaG. At least a partial explanation of this effect is that phosphate causes a decrease in the azaG intracellular pool size.
斯塔利，D. P.（伊利诺伊大学厄巴纳分校），V. R. 斯里尼瓦桑，以及H. 奥林·哈尔沃森。8-氮鸟嘌呤对蜡状芽孢杆菌从营养生长向芽孢形成前期转变的影响。《细菌学杂志》91:1875 - 1882。1966年。——发现鸟嘌呤类似物8-氮鸟嘌呤（azaG）添加到增殖细胞中时可抑制蜡状芽孢杆菌T菌株的芽孢形成，但在向芽孢形成前期转变后添加则无抑制作用。当azaG添加到营养细胞中时，生长速率降低，但未显示出即时杀菌作用。已证明azaG仅掺入核糖核酸（RNA）中。发现所有天然嘌呤碱基和核苷均可通过阻止该类似物掺入RNA来防止azaG的抑制作用。向增殖细胞中添加亚抑制水平的C(14)-azaG会导致掺入增加，且与细胞数量增加平行。在从生长向芽孢形成前期转变时，在无净RNA分解的情况下，azaG标记迅速从细胞中去除。如果通过增加azaG浓度来抑制分化，则不会发生排出。相反，在生长结束时，净掺入停止，并建立了一种稳态条件，即掺入量等于分解量。芽孢形成前期细胞中不存在azaG降解酶。讨论了在转变时天然嘌呤与azaG的比例增加的可能性，以及那时天然嘌呤衍生物优先于azaG重新掺入RNA的可能性。这些数据与从营养生长向芽孢形成前期转变时RNA周转速率增加的假设一致。向受azaG抑制的营养细胞中添加磷酸盐缓冲液（pH 7.0，0.1 m）可导致抑制作用逆转，逆转伴随着azaG的排出。对此效应的至少部分解释是磷酸盐导致细胞内azaG池大小减小。
