The evolution of low mutation rates in experimental mutator populations of Saccharomyces cerevisiae. Saccharomyces cerevisiae

microarray experiment to test the gene expression in long term lines of mutator and non-mutator yeast. Here we use an experimental evolution approach to investigate the conditions required for evolution of a reduction in mutation rate and the mechanisms by which populations tolerate the accumulation of deleterious mutations. We find that after ~6700 generations four out of eight experimental mutator lines had evolved a decreased mutation rate. Overall design: 2 condition experiment, derived experimental evolution strains compared to their ancestor strain. We compared the expression profile of one of the mutator lines (m8) after 6700 generations with its mutator ancestor, and as a control, an evolved non mutator after 6700 generations was compared to to its non-mutator ancestor. In order to prepare cells for expression microarray, glass tubes containing 3 ml of YPD were inoculated from overnight cultures, and grown until the OD600 was approximately 0.3.

本研究通过基因芯片（microarray）实验，检测突变株系（mutator）与非突变株系（non-mutator）酿酒酵母的长期传代株系的基因表达水平。本研究采用实验进化策略，旨在探究突变率降低的进化所需条件，以及种群耐受有害突变积累的分子机制。研究结果显示，在约6700代传代后，8株实验突变株系中有4株进化出了更低的突变率。
整体实验设计：采用双条件对照实验方案，将经实验进化获得的菌株与其对应祖先菌株进行比对分析。我们将传代至6700代的其中一株突变株系（m8）与其突变祖先菌株进行基因表达谱（expression profile）比对；同时设置对照，将传代至6700代的经进化获得的非突变株系与其非突变祖先菌株进行比对分析。
为制备用于基因芯片实验的细胞样本，从过夜培养的菌液中接种3 mL YPD培养基至玻璃试管，培养至OD600值约为0.3。