Ospina Calvo Brian, Juárez Ángela B, Lagorio M Gabriela
Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Dpto. de Química Inorgánica, Analítica y Química Física, Ciudad Universitaria, Pabellón II, 1er piso, C1428EHA Buenos Aires, Argentina; CONICET, Universidad de Buenos Aires, Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina.
Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental, CONICET-Universidad de Buenos Aires, Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA), Int. Guiraldes 2160, C1428EHA CABA, Argentina.
J Photochem Photobiol B. 2025 Jun;267:113167. doi: 10.1016/j.jphotobiol.2025.113167. Epub 2025 Apr 23.
This study aims to evaluate the toxicity of Atrazine on freshwater algae by employing spectroscopic analysis (specifically the F/F ratio) and photosynthetic parameters (Fv/Fm, Fv/F, ФC, ФPSII, qP, and UQF) as bioindicators. The unicellular alga Parachlorella kessleri was selected for this investigation. Cells of Parachlorella kessleri were cultivated under axenic conditions in Bold's Basal Medium (BBM) and subsequently exposed to various concentrations of Atrazine (260, 520, and 1040 μg/L) for three distinct exposure durations (1, 60, and 360 min). Reflectance, transmittance, basal steady-state emission spectra, and variable chlorophyll-a fluorescence were recorded and analyzed for both control and treated algae groups. The results demonstrated that Atrazine inhibits electron transport in the photosynthetic chain of Parachlorella kessleri, leading to a marked decline in photosynthetic efficiency. The absorbed light energy was predominantly dissipated via the physical de-excitation pathway (ΦC), while regulated heat dissipation remained minimal-even in the absence of the herbicide-suggesting a possible deficiency in the PGR5-dependent photoprotective pathway. Among the tested fluorescence parameters, ΦPSII, derived from Kautsky kinetics, proved to be the most sensitive to Atrazine exposure, highlighting its potential use in algae-based biosensors for herbicide detection in aquatic environments. Although the OJIP method provided a faster response and detected abrupt changes in relative chlorophyll fluorescence (VOP), these changes did not correlate with herbicide concentration. Steady-state fluorescence, especially when corrected for inner filter effects, may offer a complementary, non-invasive tool for monitoring aquatic stressors. However, anomalous responses at high herbicide concentrations indicated the need for further validation under varied conditions.
本研究旨在通过采用光谱分析（具体为F/F比值）和光合参数（Fv/Fm、Fv/F、ФC、ФPSII、qP和UQF）作为生物指标，评估莠去津对淡水藻类的毒性。本研究选用了单细胞藻类凯氏拟小球藻。将凯氏拟小球藻细胞在无菌条件下于Bold基础培养基（BBM）中培养，随后暴露于不同浓度的莠去津（260、520和1040μg/L）下，暴露时间分为三个不同时段（1、60和360分钟）。记录并分析了对照藻组和处理藻组的反射率、透射率、基础稳态发射光谱以及可变叶绿素a荧光。结果表明，莠去津抑制了凯氏拟小球藻光合链中的电子传递，导致光合效率显著下降。吸收的光能主要通过物理去激发途径（ΦC）耗散，而即使在没有除草剂的情况下，调节性热耗散仍然很少，这表明可能存在依赖于PGR5的光保护途径缺陷。在测试的荧光参数中，源自考茨基动力学的ΦPSII被证明对莠去津暴露最为敏感，突出了其在基于藻类的生物传感器中用于检测水生环境中除草剂的潜在用途。尽管OJIP方法提供了更快的响应并检测到相对叶绿素荧光（VOP）的突然变化，但这些变化与除草剂浓度无关。稳态荧光，特别是在校正内滤光效应后，可能为监测水生应激源提供一种补充性的、非侵入性的工具。然而，在高除草剂浓度下的异常反应表明需要在不同条件下进行进一步验证。
