Mao Xiao-Tong, Xu Rui-Xia, Gao Yu, Li Hong-Ye, Liu Jie-Sheng, Yang Wei-Dong
Key Laboratory of Aquatic Eutrophication and Control of Harmful Algal Blooms of Guangdong Higher Education Institute, College of Life Science and Technology, Jinan University, Guangzhou 510632, China.
Key Laboratory of Aquatic Eutrophication and Control of Harmful Algal Blooms of Guangdong Higher Education Institute, College of Life Science and Technology, Jinan University, Guangzhou 510632, China.
Ecotoxicol Environ Saf. 2021 Jun 1;215:112123. doi: 10.1016/j.ecoenv.2021.112123. Epub 2021 Mar 12.
Alexandrium pacificum is a toxin-producing dinoflagellate with allelopathic effects. The elucidation of allelopathic mechanism of A. pacificum is of great significance for understanding A. pacificum blooms. To this end, using the model diatom Thalassiosira pseudonana as a target species, we observed changes in physiological, biochemical and gene transcription of T. pseudonana upon being co-cultured with A. pacificum. We found reciprocal effects between A. pacificum and T. pseudonana, and corroborated A. pacificum's allelopathy on T. pseudonana by observing inhibitory effects of filtrate from A. pacificum culture on the growth of T. pseudonana. We also found that co-culturing with A. pacificum, the expression of T. pseudonana genes related to photosynthesis, oxidative phosphorylation, antioxidant system, nutrient absorption and energy metabolism were drastically influenced. Coupled with the alterations in Fv/Fm (the variable/maximum fluorescence ratio), activity of superoxide dismutase, contents of malondialdehyde, neutral lipid and total protein in T. pseudonana co-cultured with A. pacificum, we propose that A. pacificum allelopathy could reduce the efficiency of photosynthesis and energy metabolism of T. pseudonana and caused the oxidative stress, while the nutrient absorption was also affected by allelopathic effects. The resultant data potentially uncovered the allelopathic molecular mechanism of A. pacificum to model alga T. pseudonana. The changes in nutrient uptake and even energy metabolism in T. pseudonana, as an adaptation to environmental conditions, may prevent it from stress-related injuries. Our finding might advance the understanding of allelopathic mechanism of A. pacificum.
太平洋亚历山大藻是一种能产生毒素的具有化感作用的甲藻。阐明太平洋亚历山大藻的化感作用机制对于理解其藻华现象具有重要意义。为此，我们以模式硅藻三角褐指藻为目标物种，观察了三角褐指藻与太平洋亚历山大藻共培养后生理、生化及基因转录水平的变化。我们发现太平洋亚历山大藻与三角褐指藻之间存在相互作用，并通过观察太平洋亚历山大藻培养液滤液对三角褐指藻生长的抑制作用，证实了太平洋亚历山大藻对三角褐指藻的化感作用。我们还发现，与太平洋亚历山大藻共培养时，三角褐指藻中与光合作用、氧化磷酸化、抗氧化系统、营养吸收和能量代谢相关的基因表达受到显著影响。结合与太平洋亚历山大藻共培养的三角褐指藻的Fv/Fm（可变荧光与最大荧光比值）、超氧化物歧化酶活性、丙二醛含量、中性脂质和总蛋白含量的变化，我们认为太平洋亚历山大藻的化感作用会降低三角褐指藻的光合作用和能量代谢效率，并导致氧化应激，同时营养吸收也受到化感作用的影响。这些结果可能揭示了太平洋亚历山大藻对模式藻三角褐指藻的化感分子机制。三角褐指藻中营养吸收甚至能量代谢的变化作为对环境条件的一种适应，可能使其免受与应激相关的损伤。我们的发现可能会推进对太平洋亚历山大藻化感作用机制的理解。
