Redshaw R A
J Bacteriol. 1975 Dec;124(3):1411-6. doi: 10.1128/jb.124.3.1411-1416.1975.
The germination and outgrowth of Saccharomyces cerevisiae ascospores were studied by determining the sensitivity of the ascospores to the action of chemical mutagens. Survival of the ascospores after N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) treatment was low during the first 2 h of germination and then increased and remained constant. Survival of the ascospores after 2-methoxy-6-chloro-9-(3-[ethyl-2-chloroethyl]aminopropylamino)acridine-2HC1 (ICR-170) treatment was constant from 0 to 5 h, but as the ascospores completed outgrowth at 6 h they became more sensitive to killing by ICR-170. Survival of the ascospores remained high during treatment with 2-methoxy-6-chloro-9-(3-[ethyl-2-hydroxyethyl]aminopropylamino)acridine-2HC1 (ICR-170-OH) or 2,7-diamino-10-ethyl-9-phenyl-phenanthridinium bromide. The main classes of mutations screened for were petites and auxotrophs. The induction of petites and auxotrophs by MNNG was independent of the stage of germination and outgrowth treated. Petite induction by ICR-170 was dependent upon the stage of germination and outgrowth treated. The early hours of germination (0 to 3 h) were not sensitive to petite induction. However, there was maximal petite induction at 5 h into germination and outgrowth, followed by a decline. During this same time period, ICR-170 induced less than 1% auxotrophic colonies. This finding is very unusual because ICR-170 induced 15% auxotrophic colonies in starved log-phase cultures of S. cerevisiae. The acridine ICR-170-OH induced no mutations during germination and outgrowth of the ascospores. Ethidium bromide induced petites, and the petite frequency became maximal at 5 h of germination and outgrowth, a result similar to that obtained with ICR-170.
通过测定酿酒酵母子囊孢子对化学诱变剂作用的敏感性，研究了其萌发和生长情况。在萌发的最初2小时内，经N-甲基-N'-硝基-N-亚硝基胍（MNNG）处理的子囊孢子存活率较低，随后升高并保持稳定。经2-甲氧基-6-氯-9-(3-[乙基-2-氯乙基]氨基丙基氨基)吖啶-2HCl（ICR-170）处理后，子囊孢子在0至5小时内的存活率保持稳定，但当子囊孢子在6小时完成生长时，它们对ICR-170杀伤的敏感性增加。在用2-甲氧基-6-氯-9-(3-[乙基-2-羟乙基]氨基丙基氨基)吖啶-2HCl（ICR-170-OH）或2,7-二氨基-10-乙基-9-苯基菲啶溴化物处理期间，子囊孢子的存活率保持较高。筛选的主要突变类型为小菌落和营养缺陷型。MNNG对小菌落和营养缺陷型的诱导与处理的萌发和生长阶段无关。ICR-170对小菌落的诱导取决于处理的萌发和生长阶段。萌发的早期（0至3小时）对小菌落诱导不敏感。然而，在萌发和生长5小时时小菌落诱导达到最大值，随后下降。在同一时间段内，ICR-170诱导的营养缺陷型菌落不到1%。这一发现非常不寻常，因为ICR-170在酿酒酵母饥饿对数期培养物中诱导了15%的营养缺陷型菌落。吖啶ICR-170-OH在子囊孢子萌发和生长期间未诱导突变。溴化乙锭诱导小菌落，小菌落频率在萌发和生长5小时时达到最大值，这一结果与ICR-170的结果相似。
