The Effect of High-Dose Ionizing Radiation on the Isolated Photobiont of the Astrobiological Model Lichen Circinaria gyrosa

作者：Joachim Meeßen, Theresa Backhaus, Annette Brandt, Marina Raguse, Ute Böttger, Jean‐Pierre de Vera, Rosa de la Torre · 发表于：Astrobiology · 年份：2017 · DOI：10.1089/ast.2015.1453 · 被引用次数：25 · 研究领域：Planetary Science and Exploration、Lichen and fungal ecology、Radioactive contamination and transfer

Lichen symbioses between fungi and algae represent successful life strategies to colonize the most extreme terrestrial habitats. Consequently, space exposure and simulation experiments have demonstrated lichens' high capacity for survival, and thus, they have become models in astrobiological research with which to discern the limits and limitations of terrestrial life. In a series of ground-based irradiation experiments, the STARLIFE campaign investigated the resistance of astrobiological model organisms to galactic cosmic radiation, which is one of the lethal stressors of extraterrestrial environments. Since previous studies have identified that the alga is the more sensitive lichen symbiont, we chose the isolated photobiont Trebouxia sp. of the astrobiological model Circinaria gyrosa as a subject in the campaign. Therein, γ radiation was used to exemplify the deleterious effects of low linear energy transfer (LET) ionizing radiation at extremely high doses up to 113 kGy in the context of astrobiology. The effects were analyzed by chlorophyll a fluorescence of photosystem II (PSII), cultivation assays, live/dead staining and confocal laser scanning microscopy (CLSM), and Raman laser spectroscopy (RLS). The results demonstrate dose-dependent impairment of photosynthesis, the cessation of cell proliferation, cellular damage, a decrease in metabolic activity, and degradation of photosynthetic pigments. While previous investigations on other extraterrestrial stressors have demon...