Galeota-Sprung Ben, Fernandez Amy, Sniegowski Paul
Department of Biology, University of Pennsylvania, Philadelphia, PA, USA.
R Soc Open Sci. 2022 Jul 6;9(7):211842. doi: 10.1098/rsos.211842. eCollection 2022 Jul.
We show that the mitochondrial DNA (mtDNA) copy number in growing cultures of the yeast increases by a factor of up to 4, being lowest (approx. 10 per haploid genome) and stable during rapid fermentative growth, and highest at the end of the respiratory phase. When yeast are grown on glucose, the onset of the mtDNA copy number increase coincides with the early stages of the diauxic shift, and the increase continues through respiration. A lesser yet still substantial copy number increase occurs when yeast are grown on a nonfermentable carbon source, i.e. when there is no diauxic shift. The mtDNA copy number increase during and for some time after the diauxic shift is not driven by an increase in cell size. The copy number increase occurs in both haploid and diploid strains but is markedly attenuated in a diploid wild isolate that is a ready sporulator. Strain-to-strain differences in mtDNA copy number are least apparent in fermentation and most apparent in late respiration or stationary phase. While changes in mitochondrial morphology and function were previously known to accompany changes in physiological state, it had not been previously shown that the mtDNA copy number changes substantially over time in a clonal growing culture. The mtDNA copy number in yeast is therefore a highly dynamic phenotype.
我们发现，酵母生长培养物中的线粒体DNA（mtDNA）拷贝数增加了高达4倍，在快速发酵生长期间最低（约每单倍体基因组10个）且稳定，在呼吸阶段结束时最高。当酵母在葡萄糖上生长时，mtDNA拷贝数增加的起始与双相转变的早期阶段一致，并且这种增加在呼吸过程中持续。当酵母在不可发酵碳源上生长时，即不存在双相转变时，也会发生较小但仍然显著的拷贝数增加。双相转变期间及之后一段时间内mtDNA拷贝数的增加并非由细胞大小的增加驱动。单倍体和二倍体菌株中均会发生拷贝数增加，但在易于形成孢子的二倍体野生分离株中显著减弱。mtDNA拷贝数的菌株间差异在发酵过程中最不明显，在呼吸后期或稳定期最明显。虽然之前已知线粒体形态和功能的变化伴随着生理状态的变化，但之前尚未表明在克隆生长培养物中mtDNA拷贝数会随时间发生显著变化。因此，酵母中的mtDNA拷贝数是一种高度动态的表型。
