Dykens James A, Shick J Malcolm
Biol Bull. 1984 Dec;167(3):683-697. doi: 10.2307/1541419.
The sea anemone Anthopleura elegantissima, which contains photosynthetic symbionts (zooxanthellae), responds both biochemically and behaviorally to the combined environmental stresses of exposure to sunlight and photosynthetically generated hyperbaric O. Activities of the enzymes superoxide dismutase (SOD) and catalase, which act in concert as defenses against oxygen toxicity, parallel the distribution of chlorophyll. A. elegantissima shows a finely controlled contraction behavior which shades the zooxanthellae and reduces O production, but which leaves the body column tissues directly exposed to sunlight. However, the body column contains disproportionately high SOD and catalase activities as defenses against photodynamic damage. This additional role of SOD is demonstrated by shade-adapted aposymbiotic anemones in which SOD and catalase activities increase by 590% and 100% respectively following a 7 day exposure to sunlight. In response to elevated levels of O and sunlight exposure, A. elegantissima attaches gravel and other debris to its body surface which serves as a sunscreen that effectively reduces zooxanthella expulsion during exposure to bright sunlight. Finally, anemone chlorophyll content fluctuates on a seasonal basis, varying inversely with mean solar radiation. These seasonal changes are not due to corresponding changes in the number of algal cells, but rather to changes in the chlorophyll content and chlorophyll a:c ratio of a fairly uniform standing crop of zooxanthellae.
海葵优美列指海葵（Anthopleura elegantissima）体内含有光合共生体（虫黄藻），它会对暴露于阳光和光合产生的高压氧这两种环境压力组合产生生化和行为反应。超氧化物歧化酶（SOD）和过氧化氢酶作为抵御氧毒性的协同防御酶，其活性与叶绿素的分布平行。优美列指海葵表现出精细控制的收缩行为，这种行为会为虫黄藻遮荫并减少氧的产生，但会使体柱组织直接暴露于阳光下。然而，体柱含有不成比例的高SOD和过氧化氢酶活性，作为抵御光动力损伤的防御机制。适应阴暗环境的无共生海葵证明了SOD的这一额外作用，在暴露于阳光下7天后，其SOD和过氧化氢酶活性分别增加了590%和100%。为应对升高的氧水平和阳光照射，优美列指海葵会将砾石和其他碎片附着在其体表，这些碎片起到防晒霜的作用，能有效减少在强光照射下虫黄藻的排出。最后，海葵的叶绿素含量随季节波动，与平均太阳辐射呈反比。这些季节性变化并非由于藻类细胞数量的相应变化，而是由于相当稳定的虫黄藻种群中叶绿素含量和叶绿素a:c比值的变化。
