Bugeja V C, Kleinman M J, Stanbury P F, Gingold E B
Division of Biological Sciences, Hatfield Polytechnic, UK.
J Gen Microbiol. 1989 Nov;135(11):2891-7. doi: 10.1099/00221287-135-11-2891.
The stability of the 2 mu-based yeast plasmid pJDB248 in Saccharomyces cerevisiae S150-2B(cir0) was investigated in glucose-limited chemostat culture. Plasmid-free cells were detected by loss of (plasmid-encoded) leucine prototrophy and confirmed by colony hybridization. The plasmid was considerably more stable at a high dilution rate (0.12 h-1) than at a lower dilution rate (0.05 h-1). The average plasmid copy number in the cells retaining the plasmid remained constant at approximately 50 in the high dilution rate culture whereas it rose to almost 600 in the slow dilution rate culture. However, in both cultures the overall plasmid level in the total population remained constant, indicating that plasmid segregation breaks down at the low growth rate. Similar experiments on the native 2 mu plasmid demonstrated high stability and no significant differences between the high and low growth rate cultures. It is postulated that the difference in behaviour between the native and chimeric plasmids is related to an interaction between the growth conditions and the loss of the D gene product.
在葡萄糖限制的恒化器培养中，研究了基于2μm的酵母质粒pJDB248在酿酒酵母S150 - 2B(cir0)中的稳定性。通过（质粒编码的）亮氨酸原养型的丧失来检测无质粒细胞，并通过菌落杂交进行确认。该质粒在高稀释率（0.12 h-1）下比在低稀释率（0.05 h-1）下更稳定。在高稀释率培养中，保留质粒的细胞中的平均质粒拷贝数保持在约50不变，而在低稀释率培养中则上升至近600。然而，在两种培养物中，总群体中的总体质粒水平保持恒定，这表明在低生长速率下质粒分离会失效。对天然2μm质粒进行的类似实验表明其具有高稳定性，并且高生长速率和低生长速率培养之间没有显著差异。据推测，天然质粒和嵌合质粒之间行为的差异与生长条件和D基因产物的丧失之间的相互作用有关。
