Wake R G
J Bacteriol. 1976 Jul;127(1):433-9. doi: 10.1128/jb.127.1.433-439.1976.
Spores of Bacillus subtilis W23 thy his were allowed to incorporate [3H]thymine for short periods of time either continuously from, or soon after, the start of the first round of replication after germination. They were then transferred to nonradioactive medium to allow growth into microcolonies (up to 12 cells), which were autoradiographed. The relative numbers of various types (major versus minor) of grain clusters associated with individual microcolonies throughout the populations were scored. Analysis of the results showed clearly that, in the majority of spores at least, only one chromosome was undergoing replication soon after the start of deoxyribonucleic acid synthesis. Furthermore, under the conditions used, no evidence for initiation of replication of a second chromosome within 25 min after the first could be obtained. Accepting that B. subtilis spores are essentially homogenous in deoxyribonucleic acid content, the results support the conclusion that the spore contains only one copy of the chromosome, not two.
枯草芽孢杆菌W23 thy his的孢子在萌发后第一轮复制开始后，短时间内连续或不久后掺入[3H]胸腺嘧啶。然后将它们转移到非放射性培养基中，使其生长成微菌落（最多12个细胞），并进行放射自显影。对整个群体中与各个微菌落相关的各种类型（主要与次要）颗粒簇的相对数量进行了评分。结果分析清楚地表明，至少在大多数孢子中，脱氧核糖核酸合成开始后不久只有一条染色体正在进行复制。此外，在所使用的条件下，在第一条染色体复制后25分钟内没有获得第二条染色体开始复制的证据。鉴于枯草芽孢杆菌孢子在脱氧核糖核酸含量上基本是均匀的，这些结果支持了孢子只含有一条染色体拷贝而不是两条的结论。
