Sinha R P, Hader D P
Friedrich-Alexander-Universität, Institut für Botanik und Pharmazeutische Biologie, Erlangen, Germany.
Adv Space Res. 2002;30(6):1547-56. doi: 10.1016/s0273-1177(02)00370-8.
Aquatic photosynthetic organisms are exposed to solar ultraviolet (UV) radiation while they harvest longer wavelength radiation for energetic reasons. Solar UV-B radiation (280-315 nm) affects motility and orientation in motile organisms and impairs photosynthesis in cyanobacteria, phytoplankton and macroalgae as measured by monitoring oxygen production or pulse amplitude modulated fluorescence analysis. Upon moderate UV stress most organisms respond by photoinhibition which is an active downregulation of the photosynthetic electron transport in photosystem II by degradation of UV-damaged D1 protein. Photoinhibition is readily reversible during recovery in shaded conditions. Excessive UV stress causes photodamage which is not easily reversible. Another major target is the DNA where UV-B mainly induces thymine dimers. Cyanobacteria, phytoplankton and macroalgae produce scytonemin, mycosporine-like amino acids and other UV-absorbing substances to protect themselves from short wavelength solar radiation.
水生光合生物在为获取能量而吸收较长波长辐射的同时，也会受到太阳紫外线（UV）辐射的影响。太阳UV - B辐射（280 - 315纳米）会影响游动生物的运动能力和方向，并通过监测氧气产生或脉冲幅度调制荧光分析发现，它会损害蓝细菌、浮游植物和大型藻类的光合作用。在适度的UV胁迫下，大多数生物会通过光抑制做出反应，光抑制是通过降解受UV损伤的D1蛋白，对光系统II中的光合电子传递进行主动下调。在阴凉条件下恢复过程中，光抑制很容易逆转。过度的UV胁迫会导致光损伤，而这种损伤不容易逆转。另一个主要靶点是DNA，UV - B主要在其中诱导胸腺嘧啶二聚体。蓝细菌、浮游植物和大型藻类会产生藻青素、类菌孢素氨基酸和其他紫外线吸收物质，以保护自身免受短波长太阳辐射的伤害。
