Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorst Str. 18, 22609 Hamburg, Germany.
Department of Marine Botany, Universität Bremen, Leobener Str. NW2, 28359 Bremen, Germany.
Protist. 2014 Jan;165(1):14-30. doi: 10.1016/j.protis.2013.10.002. Epub 2013 Nov 1.
The photosynthetic behaviour and composition of photosynthetic pigments of four Cosmarium strains collected from different geographic areas were examined under moderate and photoinhibitory white light by means of PAM fluorometry and high-performance liquid chromatography. Generally, all of the Cosmarium strains displayed the photosynthetic performance and the composition of xanthophyll cycle pigments corresponding to that of high-light adapted plants and algae, when grown under the standard laboratory conditions. However, photoinhibitory treatments provoked several strain- and species-specific characteristics despite the long-term cultivation in laboratory conditions. The typical arctic taxon, C. crenatum var. boldtianum, displayed an incomplete violaxanthin cycle yielding an accumulation of antheraxanthin during high light stress, which is considered as an adaptation to occasional high irradiances in the polar zone due to the albedo. So far, the violaxanthin/antheraxanthin turnover was known only in some prasinophycean algae. Antheraxanthin actively participated in the heat dissipation from PSII centres in C. crenatum, as concluded from a significant positive correlation between non-photochemical quenching (NPQ) and the quantity of antheraxanthin. In contrast, all the other Cosmarium strains displayed a complete violaxanthin de-epoxidase action during the high light treatments, as judged from the relatively high production of zeaxanthin which participated in thermal dissipation of excess energy.
采用 PAM 荧光仪和高效液相色谱法，研究了从不同地理区域采集的四种空球藻菌株在中等光照和光抑制白光下的光合行为和光合色素组成。通常，当在标准实验室条件下生长时，所有空球藻菌株都表现出与高光适应植物和藻类相对应的光合性能和叶黄素循环色素组成。然而，尽管在实验室条件下长期培养，光抑制处理还是引发了几种菌株和种特异性特征。典型的北极分类群 C. crenatum var. boldtianum 显示出不完全的紫黄质循环，在高光胁迫下积累花药黄质，这被认为是对极地由于反照率偶尔出现高光强的适应。到目前为止，只有在一些绿藻中才知道紫黄质/花药黄质的周转。花药黄质在 C. crenatum 中从 PSII 中心积极参与热耗散，这是从非光化学猝灭（NPQ）和花药黄质数量之间的显著正相关得出的结论。相比之下，所有其他空球藻菌株在高光处理期间都表现出完整的紫黄质脱环氧化酶作用，这可以从相对较高的玉米黄质产量推断出来，玉米黄质参与了多余能量的热耗散。
