基于转录组学揭示腐殖酸影响纳米三氧化二铬对小球藻的毒性机制

Transcriptomics Analysis Reveals the Impact of Humic Acid on the Toxicity of Nano-Cr_(2)O_(3) to Chlorella sp.

纳米材料(MNPs)暴露于天然水体中会与溶解性有机物(DOM)相互作用,影响其生物效应,但对于DOM作用下MNPs毒性机制的研究还不充分。分析了不同DOM对纳米三氧化二铬(nCr_(2)O_(3))胁迫条件下小球藻生长生理影响,同时基于转录组学揭示了腐殖酸(HA)和nCr_(2)O_(3)共暴露条件下对小球藻的毒性作用机理。结果表明,加入HA后,小球藻的细胞密度和光合色素含量均显著提高,这在一定程度上缓解了nCr_(2)O_(3)对藻细胞的光合活性的影响。同时,海藻酸(AA)在长期作用下加重了nCr_(2)O_(3)对小球藻的毒性效应,而牛血清蛋白(BSA)对藻细胞密度和光合活性并未产生显著的影响。在1-10mg·L^(-1)范围内,HA对nCr_(2)O_(3)的毒性缓解作用与HA浓度呈正相关,且随着培养时间的增加,HA对nCr_(2)O_(3)的毒性缓解作用更加明显。相应的,低浓度的HA就可显著减轻由n Cr_(2)O_(3)所引起藻细胞内的氧化应激,减少活性氧(ROS)的累积。通过细胞结构观察,HA可以减轻由内化的nCr_(2)O_(3)对叶绿体造成的细胞器损伤,减少细胞空泡化,同时形成具有解毒功能的电子致密颗粒。转录组结果显示,加入HA使DNA复制相关基因表达上调,以及通过影响藻细胞碳水化物代谢和脂质代谢过程来缓解nCr_(2)O_(3)的毒性作用。因此,HA通过与nCr_(2)O_(3)相互作用,诱导小球藻内相关基因表达水平的变化来缓解nCr_(2)O_(3)的毒性效应。该研究从分子层面对进一步明确纳米颗粒在实际水体中的生物效应及控制策略提供理论依据。

Nanomaterials (MNPs) can interact with dissolved organic matter (DOM) and affect its biological effects when exposed to natural water.However,the toxicity mechanism of MNPs under the action of DOM has not yet been fully studied.This study analyzed the effects of different DOM concentrations on the growth and physiology of Chlorella sp.under nCr_(2)O_(3) stress conditions.Furthermore,transcriptomic analysis was performed to elucidate the toxic mechanisms of humic acid (HA) and nCr_(2)O_(3) in Chlorella sp.The results showed that the cell density and photosynthetic pigment content of Chlorella sp.increased significantly after HA addition,which alleviated the effect of nCr_(2)O_(3) on the photosynthetic activity of algal cells to a certain extent.Simultaneously,alginate (AA) aggravated the toxic effect of nCr_(2)O_(3) on Chlorella sp.under long-term action,whereas the addition of bovine serum albumin (BSA) had no significant effect on algal cell density and photosynthetic activity.Within the concentration range of 1-10 mg·L^(-1),the mitigating effect of HA on nCr_(2)O_(3) toxicity was positively correlated with the HA concentration,and the toxicity mitigation effect of HA on nCr_(2)O_(3) was more obvious with increasing treatment time.Correspondingly,low concentrations of HA significantly reduced oxidative stress induced by nCr_(2)O_(3) in algal cells and decreased reactive oxygen species (ROS) accumulation.Through observation of the cell structure,HA could alleviate organelle damage caused by internalized nCr_(2)O_(3) in chloroplasts,reduce cell vacuolization,and form electron-dense particles with detoxifying functions.Transcriptomic analysis indicated that HA addition upregulated the expression of DNA replicationrelated genes and alleviated the toxic effects of nCr_(2)O_(3) by affecting carbohydrate and lipid metabolism in algal cells.Therefore,HA mitigates the toxic effects of nCr_(2)O_(3) through interactions that induce changes in the expression of the relevant genes in Chlorella sp.This study provides a theoretical basis for further clarifying the biological effects and control strategies of nanoparticles in water bodies at the molecular level.