Jamet-Vierny C, Anagnostopoulos C
Genetics. 1975 Nov;81(3):437-58. doi: 10.1093/genetics/81.3.437.
A small fraction (about 0.5%) of the transformants for a particular marker of B. subtilis (ilvA4; most probably a deletion) were found to be relatively unstable merodiploids. They possess a redundancy of the metB-ilvA chromosome segment. When their DNA is used as donor in transformation a merodiploid condition for the whole of this segment is created in all ilvA4+ transformants. For several of the duplicated loci both copies often are of recipient strain origin. Markers originally belonging to different copies of the diploidized region can be cotransferred in PBS1-mediated transduction. The data are well in agreement with the hypothesis that the merodiploids carry a tandem duplication. An alternative hypothesis which does not call for integration of the exogenote within the recipient chromosome was also considered. Models are proposed for interpreting the segregation of the merodiploids, the transmission of the diploid state and its generation during transformation of the ilvA4 marker by wild-type DNA.
已发现枯草芽孢杆菌特定标记（ilvA4；很可能是一个缺失）的一小部分转化子（约0.5%）是相对不稳定的部分二倍体。它们拥有metB-ilvA染色体片段的冗余。当用它们的DNA作为转化供体时，在所有ilvA4+转化子中会产生该整个片段的部分二倍体状态。对于几个重复位点，两个拷贝通常都来源于受体菌株。最初属于二倍体化区域不同拷贝的标记可以在PBS1介导的转导中共转移。这些数据与部分二倍体携带串联重复的假说是完全一致的。还考虑了另一种不要求外基因子整合到受体染色体内的假说。提出了一些模型来解释部分二倍体的分离、二倍体状态的传递及其在野生型DNA转化ilvA4标记过程中的产生。
