Department of Agriculture, Food and Environment, University of Pisa, Via Mariscoglio 34, 56124 Pisa, Italy.
Institute of Agricultural Biology and Biotechnology, Italian National Research Council, Via Moruzzi 1, 56124 Pisa, Italy.
Int J Mol Sci. 2023 Jan 10;24(2):1346. doi: 10.3390/ijms24021346.
The differential effects of UV-B on the inhibition or activation of protective mechanisms to maintain cells photosynthetically active were investigated in native microalgae. Four strains were used, including two strains, F4 and LG1, isolated from a Mediterranean inland swamp and a recycled cigarette butt's substrate, respectively, and two isolates from an Ecuadorian highland lake related to (PEC) and (ETI). Monocultures were exposed to acute UV-B (1.7 W m) over 18 h under controlled conditions. UV-B-untreated microalgae were used as the control. Comparative physiological responses, including photosynthetic pigments, non-enzymatic antioxidants, and chlorophyll fluorescence, were evaluated at specific time points. Results showed that UV-B significantly compromised all the physiological parameters in F4, thereby resulting in the most UV-B-sensitive strain. Contrarily, UV-B exposure did not lead to changes in the PEC physiological traits, resulting in the best UV-B-resistant strain. This could be attributed to the acclimation to high light habitat, where maintaining a constitutive phenotype (at the photosynthetic level) is strategically advantageous. Differently, LG1 and ETI at 12 h of UV-B exposure showed different UV-B responses, which is probably related to acclimation, where in LG1, the pigments were recovered, and the antioxidants were still functioning, while in ETI, the accumulation of pigments and antioxidants was increased to avoid further photodamage. Consequently, the prolonged exposure in LG1 and ETI resulted in species-specific metabolic regulation (e.g., non-enzymatic antioxidants) in order to constrain full photoinhibition under acute UV-B.
本研究旨在探究 UV-B 对维持原生微藻细胞光合活性的保护机制的抑制或激活的差异效应。使用了四种菌株，包括两种从地中海内陆沼泽和回收香烟滤嘴基质中分离的菌株 F4 和 LG1，以及两种与（PEC）和（ETI）相关的厄瓜多尔高地湖泊的分离物。在受控条件下，将单培养物暴露于急性 UV-B（1.7 W m）下 18 小时。未接受 UV-B 处理的微藻作为对照。在特定时间点评估了比较生理响应，包括光合色素、非酶抗氧化剂和叶绿素荧光。结果表明，UV-B 显著损害了 F4 中的所有生理参数，从而使其成为最敏感的菌株。相反，UV-B 暴露并未导致 PEC 的生理特征发生变化，使其成为最具耐 UV-B 能力的菌株。这可能归因于对高光生境的适应，在这种环境中，维持组成型表型（在光合水平上）具有战略优势。相反，在 12 小时的 UV-B 暴露下，LG1 和 ETI 表现出不同的 UV-B 响应，这可能与适应有关，在 LG1 中，色素得到了恢复，抗氧化剂仍在发挥作用，而在 ETI 中，色素和抗氧化剂的积累增加以避免进一步的光损伤。因此，LG1 和 ETI 的长时间暴露导致了特定物种的代谢调节（例如，非酶抗氧化剂），以便在急性 UV-B 下限制完全光抑制。
