Darlington A J, Scazzocchio C
J Bacteriol. 1967 Mar;93(3):937-40. doi: 10.1128/jb.93.3.937-940.1967.
Aspergillus mutants resistant to various purine analogues (purine, 8-azaguanine, 2-thioxanthine, and 2-thiouric acid) are defective in at least one step of purine uptake or breakdown. The properties of these mutants show that there are two uptake systems for purines, one which mediates the uptake of hypoxanthine, guanine, and adenine, and the other, xanthine and uric acid. Allantoinase-less strains are sensitive to the toxic effects of allantoin accumulation. They are severely inhibited when grown in the presence of naturally occurring purines. Mutant strains derived from these, resistant to naturally occurring purines, may be isolated. These are either wild-type revertants, or carry a second metabolic block in the uptake or breakdown of purines. The properties of these double mutants confirm the interpretation of the nature of the analogue-resistant mutants.
对各种嘌呤类似物（嘌呤、8-氮杂鸟嘌呤、2-硫代黄嘌呤和2-硫代尿酸）具有抗性的曲霉突变体在嘌呤摄取或分解的至少一个步骤中存在缺陷。这些突变体的特性表明，存在两种嘌呤摄取系统，一种介导次黄嘌呤、鸟嘌呤和腺嘌呤的摄取，另一种介导黄嘌呤和尿酸的摄取。缺乏尿囊素酶的菌株对尿囊素积累的毒性作用敏感。当在天然存在的嘌呤存在下生长时，它们会受到严重抑制。可以分离出源自这些菌株的对天然存在的嘌呤具有抗性的突变菌株。这些要么是野生型回复体，要么在嘌呤的摄取或分解中存在第二个代谢障碍。这些双突变体的特性证实了对类似物抗性突变体性质的解释。
