Biotechnology Division, Department of Cell and Molecular Biology, Faculty of Chemistry, University of Kashan, Kashan, Iran. 8731753153, Iran.
Biotechnology Division, Department of Cell and Molecular Biology, Faculty of Chemistry, University of Kashan, Kashan, Iran. 8731753153, Iran.
Ecotoxicol Environ Saf. 2020 Apr 1;192:110261. doi: 10.1016/j.ecoenv.2020.110261. Epub 2020 Feb 1.
The Chlorella vulgaris has been generally recognized as a promising microalgal model to study stress-related responses due to its ability to withstand against ionizing and non-ionizing radiation. The objective of the present study was to investigate the effect of CaCl pre-treatment at different concentrations on the responses of microalga C. vulgaris under gamma radiation toxicity. Changes in growth, physiological parameters and biochemical compositions of the algae pretreated with 0.17 (normal), 5, and 10 mM CaCl were analyzed under 300 Gy gamma irradiation and compared to those of gamma-free control. The results showed that parameters including specific growth rate, cell size, chlorophyll and protein contents, ascorbate peroxidase (APX), and superoxide dismutase (SOD) activity, Ferric Reducing Antioxidant Power (FRAP), and the ratios of nucleic acid to protein negatively affected by gamma irradiation. All these parameters, except for the ratios of nucleic acid to protein significantly increased in the algae when pretreated with a CaCl content higher than normal concentration. The analysis also showed that parameters including catalase activity, proline, and carotenoid content, the level of lipid peroxidation, and electrolyte leakage (EL) significantly increased under gamma irradiation but not affected significantly under different CaCl pre-treatments. Additionally, specific growth rate, chlorophyll a and protein content, APX and SOD activity, FRAP, lipid peroxidation, electrolyte leakage, and the ratios of nucleic acid to protein were the only parameters that significantly affected by the interaction of gamma toxicity and CaCl pretreatment. Overall, the results suggested that regardless of the CaCl effect, the algal cells responded to gamma radiation more efficiently by increasing proline, carotenoids content, and CAT activity. More important, it was concluded that calcium had an essential role in modifying the detrimental effect of gamma toxicity on the algae mainly by increasing the activity of ascorbate peroxidase and superoxide dismutase and maintaining the reducing antioxidant power (FRAP) of the cells at a high level.
小球藻通常被认为是一种很有前途的微藻模式生物，可用于研究与应激相关的反应，因为它能够耐受电离和非电离辐射。本研究的目的是研究不同浓度 CaCl2 预处理对γ辐射毒性下微藻 C. vulgaris 响应的影响。分析了用 0.17（正常）、5 和 10 mM CaCl2 预处理的藻类在 300 Gyγ辐射下的生长、生理参数和生化成分的变化，并与无γ辐射对照进行了比较。结果表明，包括比生长速率、细胞大小、叶绿素和蛋白质含量、抗坏血酸过氧化物酶（APX）和超氧化物歧化酶（SOD）活性、铁还原抗氧化能力（FRAP）以及受γ辐射负面影响的核酸与蛋白质比值在内的参数均降低。除了核酸与蛋白质的比值外，所有这些参数在藻类用高于正常浓度的 CaCl2 预处理时均显著增加。分析还表明，包括过氧化氢酶活性、脯氨酸、类胡萝卜素含量、脂质过氧化水平和电解质泄漏（EL）在内的参数在γ辐射下显著增加，但在不同 CaCl2 预处理下无显著影响。此外，比生长速率、叶绿素 a 和蛋白质含量、APX 和 SOD 活性、FRAP、脂质过氧化、电解质泄漏和核酸与蛋白质的比值是受γ毒性和 CaCl2 预处理相互作用影响的唯一参数。总体而言，结果表明，无论 CaCl2 的影响如何，藻类细胞通过增加脯氨酸、类胡萝卜素含量和 CAT 活性来更有效地应对γ辐射。更重要的是，研究结果表明，钙在修饰γ毒性对藻类的有害影响方面起着重要作用，主要是通过增加抗坏血酸过氧化物酶和超氧化物歧化酶的活性以及维持细胞的高还原抗氧化能力（FRAP）来实现的。
