Interactive effects of solar UV-B-radiation and nutrient supply on the formation and detoxification of oxidative stress and its consequences to growth of green marine macroalgae

人为土地利用造成的沿海生态系统富营养化是一个日益严重的世界性问题。因此，促进了机会性绿色大型藻类的快速生长，这可在适当的环境条件下导致大型藻类大量繁殖。与此相反，水圈中太阳紫外线B（UV-B）辐射不成比例地高，由于人为的平流层臭氧消耗，局部和季节性地增加，大大损害了大型藻类的生长。本研究的目的是在空间和时间分辨率上表征这两种拮抗性环境因素之间的相互作用，并阐明其潜在的生理机制。石莼属的形成水华的绿色大型藻类被用作模式生物。氮同化对活性氧（ROS）的形成和解毒的影响是研究的中心课题。由此产生的影响的增长的macrophages可以提供解释其生存在不利条件下的领域。氮同化和Mehler反应之间的竞争电子，这源于光合电子传递，在生理实验室研究。氮同化的潜力，以避免UV-B诱导的氧化胁迫是这些研究的主要课题。为了了解这些过程在自然条件下，UV-B-实验进行有关的季节性波动的氮供应。此外，不同的无机氮的历史对大型藻类的氧化胁迫所造成的高夏季UV-B辐射的影响进行了深入的调查，在现场条件下，石莼。

The eutrophication of coastal ecosystems resulting from anthropogenic land-use is an increasingly growing problem worldwide. Thus, the rapid growth of opportunistic green macroalgae is promoted, which can lead under appropriate environmental conditions to large macroalgal blooms. In contrast, disproportionately high solar ultraviolet B (UV-B) radiation in the hydrosphere, which increases locally and seasonally as a consequence of anthropogenic stratospheric ozone depletion, impairs macroalgal growth significantly. The aim of this research is to characterize the interactive effects between the two antagonistic environmental factors in spatial and temporal resolution and to elucidate the underlying physiological mechanisms. A bloom-forming green macroalga of the genus Ulva is intended to serve as a model organism. The impact of nitrogen assimilation on the formation and detoxification of reactive oxygen species (ROS) is the central subject of the investigation. The resulting implications for the growth of the macroalga can provide explanations for its survival under adverse conditions in the field. The competition between nitrogen assimilation and the Mehler reaction for electrons, which originate from the photosynthetic electron transport, is investigated in physiological laboratory studies. The potential of nitrogen assimilation in order to avoid UV-B-induced oxidative stress is the main subject of these studies. To understand these processes under natural conditions, UV-B-experiments are conducted in relation to the seasonally fluctuating nitrogen availability. Furthermore, the impact of different inorganic nitrogen histories on macroalgal oxidative stress caused by high summer UV-B-radiation is thoroughly investigated under field conditions in Ulva sp.