Gao Kunshan, Guan Wanchun, Helbling E Walter
Marine Biology Institute, Shantou University, Shantou, Guangdong 515063, China.
J Photochem Photobiol B. 2007 Feb 1;86(2):140-8. doi: 10.1016/j.jphotobiol.2006.05.007. Epub 2006 Oct 11.
In order to assess the short- and long-term impacts of UV radiation (UVR, 280-400nm) on the red tide alga, Heterosigma akashiwo, we exposed the cells to three different solar radiation treatments (PAB: 280-700nm, PA: 320-700nm, P: 400-700nm) under both solar and artificial radiation. A significant decrease in the effective quantum yield (Y) during high irradiance periods (i.e., local noon) was observed, but the cells partially recovered during the evening hours. Exposure to high irradiances for 15, 30, and 60min under a solar simulator followed by the recovery (8h) under dark, 9 and 100micromolphotonsm(-2)s(-1) of PAR, highlighted the importance of the irradiance level during the recovery period. Regardless the radiation treatments, the highest recovery (both in rate and total Y) was found at a PAR irradiance of 9micromolphotonsm(-2)s(-1), while the lowest was observed at 100micromolphotonsm(-2)s(-1). In all experiments, PAR was responsible for most of the observed inhibition; nevertheless, the cells exposed only to PAR had the highest recovery in any condition, as compared to the other radiation treatments. In long-term experiments (10 days) using semi-continuous cultures, there was a significant increase of UV-absorbing compounds (UV(abc)) per cell from 1.2 to >4x10(-6)microgUV(abc)cell(-1) during the first 3-5 days of exposure to solar radiation. The highest concentration of UV(abc) was found in samples exposed in the PAB as compared to PA and P treatments. Growth rates (mu) mimic the behavior of UV-absorbing compounds, and during the first 5 days mu increased from <0.2 to ca. 0.8, and stayed relatively constant at this value during the rest of the experiment. The inhibition of the Y decreased with increasing acclimation of cells. All our data indicates that H. akashiwo is a sensitive species, but was able acclimate relatively fast (3-5 days) synthesizing UV-absorbing compounds and thus reducing any impact either on photosystem II or on growth.
为了评估紫外线辐射（UVR，280 - 400nm）对赤潮藻——赤潮异弯藻的短期和长期影响，我们在自然辐射和人工辐射条件下，将细胞暴露于三种不同的太阳辐射处理（PAB：280 - 700nm，PA：320 - 700nm，P：400 - 700nm）下。在高辐照期（即当地正午）观察到有效量子产率（Y）显著下降，但细胞在傍晚时分部分恢复。在太阳模拟器下将细胞暴露于高辐照度15、30和60分钟，随后在黑暗、9和100微摩尔光子·米⁻²·秒⁻¹的光合有效辐射（PAR）下恢复8小时，这突出了恢复期辐照度水平的重要性。无论辐射处理如何，在PAR辐照度为9微摩尔光子·米⁻²·秒⁻¹时发现恢复率最高（包括速率和总Y），而在100微摩尔光子·米⁻²·秒⁻¹时观察到恢复率最低。在所有实验中，PAR是观察到的大部分抑制作用的原因；然而，与其他辐射处理相比，仅暴露于PAR的细胞在任何条件下恢复率最高。在使用半连续培养的长期实验（10天）中，在暴露于太阳辐射的前3 - 5天，每个细胞的紫外线吸收化合物（UV(abc)）显著增加，从1.2增加到>4×10⁻⁶微克UV(abc)·细胞⁻¹。与PA和P处理相比，在PAB处理下暴露的样品中发现UV(abc)的浓度最高。生长速率（μ）模拟紫外线吸收化合物的行为，在最初5天内，μ从<0.2增加到约0.8，并在实验的其余时间保持相对稳定。随着细胞适应程度的增加，对Y的抑制作用降低。我们所有的数据表明，赤潮异弯藻是一个敏感物种，但能够相对快速地适应（3 - 5天），合成紫外线吸收化合物，从而减少对光系统II或生长的任何影响。
