Young M
J Gen Microbiol. 1984 Jul;130(7):1613-21. doi: 10.1099/00221287-130-7-1613.
A strain of Bacillus subtilis that carries in its genome a staphylococcal chloramphenicol acetyltransferase gene (from pC194) responds to growth at different concentrations of chloramphenicol by an alteration in the number of copies per genome of the sequences encoding the gene. Growth at 20 micrograms chloramphenicol ml-1 results in a 15-fold amplification of the sequences, whereas growth in the absence of chloramphenicol results in their loss. The mechanism of in situ amplification probably has much in common with that involved in 'R factor transitioning'. The hybridization procedures that have been used for accurately determining the number of copies of the amplified DNA sequences are potentially useful for plasmid copy number determination. The findings reported here also provide a potentially useful alternative to more conventional cloning strategies that are based on autonomous plasmids in B. subtilis. The particular advantages that can be envisaged include enhanced stability of the cloned sequences and control of the number of copies that are present.
一种基因组中携带葡萄球菌氯霉素乙酰转移酶基因（来自pC194）的枯草芽孢杆菌菌株，在不同浓度氯霉素条件下生长时，其基因组中编码该基因的序列拷贝数会发生改变。在20微克/毫升氯霉素中生长会导致该序列15倍的扩增，而在无氯霉素条件下生长则会导致其丢失。原位扩增机制可能与“R因子转变”所涉及的机制有很多共同之处。用于准确测定扩增DNA序列拷贝数的杂交方法可能对质粒拷贝数的测定有用。本文报道的研究结果还为基于枯草芽孢杆菌自主质粒的更传统克隆策略提供了一种潜在有用的替代方法。可以设想的特别优势包括克隆序列稳定性增强以及对存在的拷贝数的控制。
