Institute for Polar Ecology, University of Kiel, Wischhofstr. 1-3, 24148 Kiel, Germany.
Protoplasma. 2010 Jul;243(1-4):105-16. doi: 10.1007/s00709-009-0037-8. Epub 2009 Mar 19.
Exposure of the filamentous turf green alga Urospora penicilliformis to ambient and artificial ultraviolet radiation (UVR) revealed a considerable resilient species. This explains the ability of this alga to thrive in the middle-upper intertidal zones of the Arctic sea where it is periodically exposed to environmental extremes. A transient UVR effect on photosynthesis under photosynthetically active radiation (PAR) + UV-A and PAR + UV-A + UV-B was found, but dynamic recovery of photoinhibition was observed immediately after reduction of the photon fluence rate of PAR in the absence or presence of background UVR under laboratory and natural solar radiation, respectively. Chlorophylls, carotenoids, and xanthophyll cycle pigments (violaxanthin, antheraxanthin, and zeaxanthin) concentrations were not significantly different between freshly collected samples and filaments exposed to additional laboratory radiation treatment. The ultrastructure of the U. penicilliformis gametophytes showed that the cells are well adapted to UVR. No significant ultrastructural alterations were observed in filaments exposed to different spectral irradiance in the laboratory compared to in situ acclimated specimen. The antioxidant alpha-tocopherol was detected in minute quantity while the search for flavonoid-like compounds was negative. Other UV screening strategies or certain genetically fixed physiological protective mechanism could be operating in this species responsible for their occurrence in higher shoreline and ecological success. Further molecular and biochemical studies are needed to elucidate the stress resistance in this turf alga. There is an indication that the extremely thick cell wall of U. penicilliformis gametophytes covered with mucilage sheath and dense layer of mineral depositions may provide a shield against unfavorable environmental conditions in general and against UVR in particular.
丝状草坪绿藻 Urospora penicilliformis 暴露于环境和人工紫外线辐射（UVR）下，表现出相当的弹性。这解释了该藻类能够在北极海域中潮间带中部和上部繁盛的原因，因为那里它会周期性地暴露于极端环境中。在光合有效辐射（PAR）+UV-A 和 PAR + UV-A + UV-B 下，光合作用会受到短暂的 UVR 影响，但在实验室和自然太阳辐射下，当 PAR 的光量子通量率降低时，会观察到光抑制的动态恢复，而无需或存在背景 UVR。叶绿素、类胡萝卜素和叶黄素循环色素（堇菜黄质、玉米黄质和叶黄素）的浓度在新鲜采集的样品和暴露于额外实验室辐射处理的丝状藻之间没有显著差异。U. penicilliformis 配子体的超微结构表明，这些细胞很好地适应了 UVR。与原位驯化标本相比，暴露于不同光谱辐照度的丝状藻在实验室中没有观察到明显的超微结构改变。虽然未检测到类黄酮化合物，但检测到了微量的抗氧化剂α-生育酚。可能存在某些负责其在更高潮间带和生态成功中出现的 UV 筛选策略或特定的遗传固定生理保护机制。需要进一步的分子和生化研究来阐明该草坪藻的抗应激能力。有迹象表明，U. penicilliformis 配子体的极厚细胞壁，覆盖有黏液鞘和密集的矿物质沉积层，可能为其提供了一般环境条件和特别是 UVR 的保护。
