Sivan S, Zaritsky A, Kagan-Zur V
Department of Biology, Ben Gurion University of the Negev, Beer Sheva, Israel.
J Bacteriol. 1988 Jul;170(7):3089-93. doi: 10.1128/jb.170.7.3089-3093.1988.
The question of whether bacteriophage Mu prefers replication forks for lysogenic integration into Escherichia coli chromosomes was tested by using two different systems. In the first, inactivation of genes was scored in synchronized cultures infected by Mu at various times. No increase in the mutation frequency of a gene was found after infection at the time of its replication. In the second, the composition of colonies formed by bacteria lysogenized by Mu was determined; the newly formed lysogens should give rise to mixed colonies (containing lysogenized as well as nonlysogenized bacteria), uniform colonies, or both, depending on the mode of integration. Both types of colonies were found, and the fraction of uniform colonies was proportional to the relative length of the unreplicated segment of an average chromosome in the culture. The results in both systems clearly preclude the possibility that a lysogenizing Mu integrates with high preference at the chromosome replication forks.
利用两种不同的系统对噬菌体Mu是否更倾向于在溶原性整合到大肠杆菌染色体时选择复制叉这一问题进行了测试。在第一个系统中，对在不同时间被Mu感染的同步培养物中基因的失活情况进行评分。在基因复制时感染后，未发现该基因的突变频率增加。在第二个系统中，确定了由Mu溶原化的细菌形成的菌落组成；新形成的溶原菌应产生混合菌落（包含溶原化和未溶原化的细菌）、均匀菌落或两者皆有，这取决于整合模式。两种菌落都被发现了，并且均匀菌落的比例与培养物中平均染色体未复制片段的相对长度成正比。两个系统的结果都明确排除了溶原性Mu在染色体复制叉处高度优先整合的可能性。
