Ferrara Maria Antonietta, Cavalletti Elena, Bianco Vittorio, Miccio Lisa, Coppola Giuseppe, Ferraro Pietro, Sardo Angela
Institute of Applied Sciences and Intelligent Systems, Unit of Naples, Italian National Research Council (ISASI-CNR), Via Pietro Castellino 111, Naples, Italy.
Department of Ecosustainable Marine Biotechnology, Stazione Zoologica Anton Dohrn, Naples, Italy.
PLoS One. 2025 May 8;20(5):e0322960. doi: 10.1371/journal.pone.0322960. eCollection 2025.
Heavy metal contamination in aquatic environments poses a significant threat to microbial communities, yet the subcellular responses of phytoplankton to metal stress remain poorly understood. In particular, the effects of heavy metal exposure on the structural and physiological properties of diatoms require further investigation. Here, we analyze the impact of cadmium (Cd) and copper (Cu) exposure on the subcellular structures of the diatom Skeletonema pseudocostatum using holographic tomography. This imaging technique enables detailed visualization and quantitative analysis of diatom subcomponents, including frustules, protoplasm, vacuoles, and chloroplasts, under varying metal concentrations. The study aims to understand the changes in the mean refractive index (RI) and concentration (e.g., the ratio among cell dry mass and its biovolume) as indicators of cellular response to metal stress and to infer if such diatom can be used as sentinel species of heavy metal pollution. Findings indicate that diatoms exhibit significant variations in RI and internal cell density when exposed to different metal concentrations. Lower RI values observed at higher metal concentrations, can be considered as a sign of stress due to cytoplasm extrusion and/or vacuolization. The results highlight the potential of using S. pseudocostatum as a bioindicator for monitoring water metal pollution. Moreover, the results show that holographic tomography as useful tool for non-invasive, high-resolution cellular imaging of phytoplankton in environmental studies.
水生环境中的重金属污染对微生物群落构成了重大威胁，然而浮游植物对金属胁迫的亚细胞反应仍知之甚少。特别是，重金属暴露对硅藻结构和生理特性的影响需要进一步研究。在此，我们使用全息断层扫描分析镉（Cd）和铜（Cu）暴露对硅藻假微型海链藻亚细胞结构的影响。这种成像技术能够在不同金属浓度下对硅藻的亚组分进行详细可视化和定量分析，包括壳套、原生质、液泡和叶绿体。该研究旨在了解平均折射率（RI）和浓度的变化（例如细胞干质量与其生物体积之比），作为细胞对金属胁迫反应的指标，并推断这种硅藻是否可作为重金属污染的指示物种。研究结果表明，当暴露于不同金属浓度时，硅藻的RI和细胞内密度会出现显著变化。在较高金属浓度下观察到的较低RI值，可被视为由于细胞质挤压和/或液泡化导致的胁迫迹象。结果突出了使用假微型海链藻作为监测水体金属污染生物指示物的潜力。此外，结果表明全息断层扫描是环境研究中用于浮游植物非侵入性、高分辨率细胞成像的有用工具。
