Radiation continuously varies in the environment, exposing phototrophic organisms to diverse compositions and ratios among photosynthetically active radiation (PAR), UV-A (Ultraviolet A radiation) and UV-B (Ultraviolet B radiation). In this sense, UV radiation can control, either positively or negatively, the physiology and metabolism of marine organisms in intertidal areas. Our study focused on the exposure of Gracilaria tenuistipitata to variable combinations of radiation, evaluating its physiology, photoprotective strategies and DNA damage under each condition. To accomplish this, algal apical fragments were acclimated to three radiation treatments (PAR, PAR + UV-A and PAR + UV-A + UV-B) for one week. Thereafter, PAR-acclimated samples were moved to PAR (control), PAR + UV-A + UV-B and PAR + UV-B. PAR + UV-A-acclimated samples were moved to PAR + UV-A (control), PAR + UV-A + UV-B and PAR + UV-B, and PAR + UVR-acclimated thalli were placed in PAR + UV-A + UV-B (control), PAR + UV-B and PAR. Samples remained in these conditions for a period of 48 h continuously. Photosynthetic parameters from chlorophyll a fluorescence were evaluated, as well as growth rates, mycosporine-like amino acids, chlorophyll a, and carotenoid contents. In addition, DNA damage was assessed by detecting cyclobutane pyrimidin dimer. Expression of photolyases, ascorbate peroxidase and gluthatione peroxidase was also analyzed at the end of experimental period. Mycosporine-like amino acids were stimulated by UV radiation. DNA damage occurred only when UV-B was provided separately. In some cases, photoacclimation procedures were activated, while in others, it was not enough. In other words, although some tolerance was observed, the species could suffer the consequences of excessive energy present in some specific treatments, e.g., PAR + UV-B. After exposure to variable radiation, it was concluded that our model organism presented acclimation depending of spectral availability, including regulation of photoprotective strategies.

辐射在环境中不断变化，使光养生物暴露于光合有效辐射（PAR），UV-A（紫外线A辐射）和UV-B（紫外线B辐射）之间的不同组成和比例。从这个意义上讲，紫外线辐射可以积极或消极地控制潮间带海洋生物的生理和新陈代谢。我们的研究侧重于江cil（Gracilaria tenuistipitata）的暴露改变辐射的组合，评估每种条件下的生理，光保护策略和DNA损伤。为此，将藻类顶端碎片适应了三种放射治疗（PAR，PAR + UV-A和PAR + UV-A + UV-B）一周。之后，将适应PAR的样品移至PAR（对照），PAR + UV-A + UV-B和PAR + UV-B。将PAR + UV-A适应的样品移至PAR + UV-A（对照），将PAR + UV-A + UV-B和PAR + UV-B移至PAR + UVR适应的thalli置于PAR + UV-A A + UV-B（对照），PAR + UV-B和PAR。样品在这些条件下连续放置48小时。评估了叶绿素a荧光的光合参数，以及生长速率，霉菌素样氨基酸，叶绿素a和类胡萝卜素含量。另外，通过检测环丁烷嘧啶二聚体来评估DNA损伤。在实验期末还分析了光解酶，抗坏血酸过氧化物酶和谷胱甘肽过氧化物酶的表达。霉菌素样氨基酸被紫外线辐射刺激。仅当单独提供UV-B时才会发生DNA损伤。在某些情况下，激活了光适应程序，而在其他情况下，这还不够。换句话说，尽管观察到了一定的耐受性，但该物种可能遭受某些特定处理（例如PAR + UV-B）中存在的过多能量的后果。在暴露于可变辐射后，得出的结论是，我们的模型生物体呈现出的适应性取决于光谱的可用性，包括光保护策略的调节。