Strtak Alexandra, Sathiamoorthy Sarmitha, Tang Peter S, Tsoi Kim M, Song Fayi, Anderson James B, Chan Warren C W, Shin Jumi A
Institute of Biomaterials and Biomedical Engineering, Donnelly Center for Cellular and Biomolecular Research, Chemistry, Chemical Engineering, University of Toronto , 160 College Street, Toronto, Ontario M5S 3G9, Canada.
Bioconjug Chem. 2017 Apr 19;28(4):1205-1213. doi: 10.1021/acs.bioconjchem.7b00056. Epub 2017 Feb 16.
Engineered nanomaterials are used globally in biomedical, electronic, and optical devices, and are often discarded into the environment. Cell culture experiments have shown that many inorganic nanoparticles are toxic to eukaryotic cells. Here, we show that populations of eukaryotic cells can evolve to survive chronic exposure to toxic CdSe semiconductor quantum dots (QDs). We grew yeast Saccharomyces cerevisiae for 24 days in liquid medium containing QDs prepared daily at half the minimum inhibitory concentration (MIC) of the progenitor yeast cells. After 24 days, the cells grew normally under constant exposure to QDs. We concluded that these cells evolved to resist QD toxicity. Surprisingly, when we removed QDs from the growth medium, some of the evolved cells grew poorly, i.e., they grew better in the presence of QDs. Finally, genetic analysis confirmed that the ubiquitin ligase gene bul1 was mutated in the evolved cells, which suggests that this gene may be implicated in increased CdSe QD tolerance. This study shows that chronic exposure to QDs can exert selective pressure causing irreversible genetic changes leading to adaptation.
工程纳米材料在全球范围内被用于生物医学、电子和光学设备，并且经常被丢弃到环境中。细胞培养实验表明，许多无机纳米颗粒对真核细胞有毒。在此，我们表明真核细胞群体可以进化以在长期暴露于有毒的CdSe半导体量子点（QDs）的情况下存活。我们在含有每天以祖代酵母细胞最低抑制浓度（MIC）的一半制备的量子点的液体培养基中培养酿酒酵母24天。24天后，细胞在持续暴露于量子点的情况下正常生长。我们得出结论，这些细胞进化出了抵抗量子点毒性的能力。令人惊讶的是，当我们从生长培养基中去除量子点时，一些进化后的细胞生长不佳，即它们在量子点存在的情况下生长得更好。最后，遗传分析证实进化后的细胞中泛素连接酶基因bul1发生了突变，这表明该基因可能与CdSe量子点耐受性增加有关。这项研究表明，长期暴露于量子点可以施加选择压力，导致不可逆的基因变化从而产生适应性。
