Department of Civil & Environmental Engineering, 360 Huntington Avenue, Northeastern University, Boston, MA 02115, USA.
Department of Chemistry and Chemical Biology, 360 Huntington Avenue, Northeastern University, Boston, MA 02115, USA.
Sci Total Environ. 2015 Apr 15;512-513:345-352. doi: 10.1016/j.scitotenv.2015.01.037. Epub 2015 Jan 27.
The widely and increasing use of nano-titanium dioxide (nTiO2) has led to its release in the environment and concerns of consequent impact on aquatic eco-relevant biota. Previous studies indicated possible physiological changes (i.e., nitrogen storage) induced by nano-titanium dioxide (nTiO2) exposure in algae, which will likely have ecological implications. This study investigated the short- (96 h) and long-term (21 days) ecotoxic impact of environmentally relevant nTiO2 concentrations on the cellular biochemical pools and nutrient stoichiometry in the nitrogen-fixing cyanobacteria Anabaena variabilis. Changes in nutrient element ratios and cellular composition were analyzed using both chemical elemental analysis and Fourier Transform Infrared (FT-IR) spectroscopy. Chemical elemental analysis showed that exposure to nTiO2 at varying dose concentrations and exposure duration led to statistically significant changes in intracellular C:N, C:P and N:P stoichiometries compared with those in the controls. In general, there seemed to be a decreasing trends of cellular C:N ratio and increase in the cellular C:P and N:P ratios with the increasing level of nTiO2 exposure. Further FT-IR analysis results revealed both temporal and dose-dependent change patterns of major macromolecules, including protein, lipids, nucleic acids and carbohydrates, in A. variabilis upon nTiO2 exposure. The relative ratio of amide II, lipids, nucleic acids and carbohydrates to the cellular protein content (quantified as amide I stretch) changed significantly within the initial 96 h of exposure and, both the magnitude of changes and levels of recovery seemed to be nTiO2 dose-dependent. This study, for the first time, demonstrated that the intracellular composition and nutrient stoichiometry changes could be induced by long-term and short-term exposures to nTiO2 to primary producers, which may have ecological implications for interspecies equilibriums and community dynamics in aquatic ecosystems.
纳米二氧化钛（nTiO2）的广泛和日益增加的使用导致其在环境中释放，并引起人们对其对水生生态相关生物群产生的相应影响的关注。先前的研究表明，纳米二氧化钛（nTiO2）暴露可能会引起藻类的生理变化（例如氮储存），这可能会产生生态影响。本研究调查了环境相关浓度的纳米二氧化钛（nTiO2）对固氮蓝藻鱼腥藻的细胞生化库和营养化学计量在短期（96 小时）和长期（21 天）的生态毒性影响。使用化学元素分析和傅里叶变换红外（FT-IR）光谱分析了营养元素比和细胞组成的变化。化学元素分析表明，与对照组相比，暴露于不同剂量浓度和暴露时间的 nTiO2 会导致细胞内 C:N、C:P 和 N:P 化学计量比发生统计学上的显著变化。一般来说，随着 nTiO2 暴露水平的增加，细胞 C:N 比似乎呈下降趋势，而细胞 C:P 和 N:P 比呈上升趋势。进一步的 FT-IR 分析结果表明，鱼腥藻在 nTiO2 暴露下，主要生物大分子（包括蛋白质、脂质、核酸和碳水化合物）呈现出时间和剂量依赖性的变化模式。酰胺 II、脂质、核酸和碳水化合物与细胞蛋白质含量（以酰胺 I 伸展定量）的相对比例在暴露的最初 96 小时内发生了显著变化，并且变化的幅度和恢复水平似乎都与 nTiO2 剂量有关。本研究首次表明，长期和短期暴露于 nTiO2 可能会导致初级生产者的细胞内组成和营养化学计量发生变化，这可能对水生生态系统中的种间平衡和群落动态产生生态影响。
