André C, Gagné F
Aquatic Contaminants Research Division, Environment and Climate Change Canada, 105 McGill St., Montréal, QC H2Y 2E7, Canada.
Aquatic Contaminants Research Division, Environment and Climate Change Canada, 105 McGill St., Montréal, QC H2Y 2E7, Canada.
Comp Biochem Physiol C Toxicol Pharmacol. 2017 Jun;196:36-43. doi: 10.1016/j.cbpc.2017.03.005. Epub 2017 Mar 9.
Starving and nondividing yeast cells induce changes in the electron donor nicotinamide adenine dinucleotide (NADH) levels in a cyclic and wave-like manner for over 90min. Yeast suspensions were used to examine the toxic effects of contaminants on the cyclic behaviour of metabolite changes during anaerobic glycolysis. The cyclic behaviour NADH levels in yeast cell suspensions starved for 2 to 5h was studied after the addition of 10mM glucose for 5min followed by 10mM KCN to block aerobic glycolysis. The effects of three toxic elements (CuSO, silver nanoparticles-nAg, and GdCl), known for their potential to alter glycolsysis, on NADH levels over time were examined during the 3-h starvation step. The data were analyzed using spectral analysis (Fourier transformation) to characterize the cyclic behaviour of NADH levels during anaerobic glycolysis. Increasing the starvation time by 3h increased the amplitude of changes in NADH levels with characteristic periods of 3 to 8min. Longer starvation times decreased the amplitude of oscillations during these periods, with the appearance of NADH changes at higher frequencies. Moreover, the amplitude changes in NADH were proportional to the starvation time. Exposure to the above chemicals during the 3-h starvation time led to the formation of higher frequencies with concentration-dependent amplitude changes. In comparison with nAg and Gd, Cu was the most toxic (decreased viability the most) and produce changes at higher frequencies as well. It is noteworthy that each element produced a characteristic change in the frequency profiles, which suggests different mechanisms of action in which the severity of toxicity shifted NADH changes at higher frequencies. In conclusion, the appearance of synchronized oscillations in dense yeast populations following synchronization stress could be induced by starvation and exposure to chemicals. However, synchronicity could be abolished when cells desynchronize as a result of loss of cell viability, which contributes to heterogeneity in yeast populations, translating into NADH changes at higher frequencies. This is the first report on the influence of environmental contaminants on the cyclic or wave-like behaviour of biochemical changes in cells.
饥饿且不进行分裂的酵母细胞会以循环且类似波动的方式诱导电子供体烟酰胺腺嘌呤二核苷酸（NADH）水平变化，持续超过90分钟。酵母悬浮液被用于检测污染物对厌氧糖酵解过程中代谢物变化的循环行为的毒性作用。在添加10mM葡萄糖5分钟后，再添加10mM氰化钾以阻断有氧糖酵解，之后研究饥饿2至5小时的酵母细胞悬浮液中NADH水平的循环行为。在3小时的饥饿步骤中，检测了三种已知具有改变糖酵解潜力的有毒元素（硫酸铜、银纳米颗粒-nAg和氯化钆）对NADH水平随时间的影响。使用光谱分析（傅里叶变换）对数据进行分析，以表征厌氧糖酵解过程中NADH水平的循环行为。将饥饿时间延长3小时会增加NADH水平变化的幅度，其特征周期为3至8分钟。更长的饥饿时间会降低这些周期内振荡的幅度，同时出现更高频率的NADH变化。此外，NADH的幅度变化与饥饿时间成正比。在3小时的饥饿时间内接触上述化学物质会导致形成更高频率，且幅度变化呈浓度依赖性。与nAg和钆相比，铜的毒性最大（使活力降低最多），并且也会在更高频率产生变化。值得注意的是，每种元素在频率分布上都产生了特征性变化，这表明不同的作用机制，其中毒性的严重程度会使NADH在更高频率发生变化。总之，同步应激后密集酵母群体中同步振荡的出现可能是由饥饿和接触化学物质诱导的。然而，当细胞因活力丧失而不同步时，同步性可能会被消除，这会导致酵母群体的异质性，进而转化为更高频率的NADH变化。这是关于环境污染物对细胞生化变化的循环或类似波动行为影响的首次报道。
