State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China.
Photochem Photobiol. 2010 May-Jun;86(3):580-5. doi: 10.1111/j.1751-1097.2010.00709.x. Epub 2010 Feb 22.
UV radiation is known to inhibit photosynthetically active radiation (PAR)-driven photosynthesis; however, moderate levels of UV-A have been shown to enhance photosynthesis and growth rates of some algae. Here, we have shown that UV-A alone could drive photosynthetic utilization of bicarbonate in the red alga Gracilaria lemaneiformis as evidenced in either O(2) evolution or carbon fixation as well as pH drift. Addition of UV-B inhibited the apparent photosynthetic efficiency, raised the photosynthetic compensation point and photosynthesis-saturating irradiance level, but did not significantly affect the maximal rate of photosynthetic O(2) evolution. The electron transport inhibitor, DCMU, inhibited the photosynthesis completely, reflecting that energy of UV-A was transferred in the same way as that of PAR. Inorganic carbon acquisition for photosynthesis under UV alone was inhibited by the inhibitors of carbonic anhydrase. The results provided the evidence that G. lemaneiformis can use UV-A efficiently to drive photosynthesis based on the utilization of bicarbonate, which could contribute significantly to the enhanced photosynthesis in the presence of UV-A observed under reduced levels of solar radiation.
紫外线辐射已知会抑制光合有效辐射（PAR）驱动的光合作用；然而，适量的 UV-A 已被证明可以增强一些藻类的光合作用和生长速率。在这里，我们已经表明，仅 UV-A 就可以驱动红藻龙须菜中碳酸氢盐的光合作用利用，这表现在 O(2) 释放或碳固定以及 pH 漂移上。添加 UV-B 会抑制表观光合作用效率，提高光合作用补偿点和光合作用饱和辐照度水平，但对光合作用 O(2)释放的最大速率没有显著影响。电子传递抑制剂 DCMU 完全抑制了光合作用，这反映出 UV-A 的能量与 PAR 的能量以相同的方式传递。单独的 UV 下的光合作用无机碳获取被碳酸酐酶抑制剂抑制。这些结果提供了证据表明，龙须菜可以有效地利用 UV-A 驱动光合作用，基于对碳酸氢盐的利用，这可以显著促进在低太阳辐射下观察到的 UV-A 存在下增强的光合作用。
