Combined effects of light and naphthalene on marine microalgae

在本研究中，我研究了光和萘对海洋微藻的联合作用。强光照射（2000 μmol m^<-2> μmol s^<-1>）和萘（0.05 ~ 5 ppm）由于光抑制和毒性的综合作用，对许多浮游植物群的生长有强烈的抑制作用。微藻的叶黄素循环被认为可以防止光抑制：已知超过光合能力的光可以迅速改变绿藻的叶黄素色素，从紫黄素通过花青素到玉米黄素，而硅藻的叶黄素从二英黄质到硅黄素。当微藻暴露于浓度为>15ppm的萘中时，辐照浓度为2000 μmol m^<-2> s^<-1>时，叶黄素色素在浓度为200或2000 μmol m^<-2> s^<-1>和浓度为0或>15ppm的萘中变化最快。萘减少了溶解氧的产生，而溶解氧是光合作用的一个指标。因此萘抑制了光合作用，并迅速激活了叶黄素循环。微藻产生类真菌菌素氨基酸（MAAs），其吸光度在紫外线区最大，以防止紫外线辐射的抑制。UV-A（~360 nm）、强光照射和萘的协同作用降低了溶解氧的生成。目前尚不清楚紫外- a和萘是否改变了MAAs与叶绿素a的比值。实验中使用的微藻中MAAs的生成似乎不受UV-A和萘的影响。

In this study, I investigated the combined effects of light and naphthalene on marine microalgae. The growth of many groups of phytoplankton is strongly inhibited by combined high light irradiation(2000 μmol m^<-2> s^<-1>) and naphthalene(0.05-5 ppm) because of the combined effects of photoinhibition and toxicity. The xanthophyll cycle of microalgae is thought to protect against photoinhibition : light in excess of photosynthetic capacity is known to rapidly change xanthophyll pigments of green algae from violaxanthin via antheraxanthin to zeaxanthin, and those of diatoms from diadinoxanthin to diatoxanthin. Irradiation of microalgae at 2000 μmol m^<-2> s^<-1> during exposure to naphthalene at >15ppm caused the fastest change in xanthophyll pigments among four conditions(200 or 2000 μmol m^<-2> s^<-1> and 0 or >15 ppm naphthalene). Naphthalene decreased the production of dissolved oxygen, an indicator of photosynthesis. Therefore naphthalene inhibited photosynthesis, and rapidly activated the xanthophyll cycle. Microalgae produce mycosporine-like amino acids(MAAs), whose absorbance maxima lie in the ultraviolet(UV) region, to protect against inhibition by UV radiation. The production of dissolved oxygen was decreased by the synergistic effects of UV-A(~360 nm), high light irradiation, and naphthalene. It was not clear whether the ratio of MAAs to chlorophyll a was changed by UV-A and naphthalene. It appears that the production of MAAs in microalgae used in this experiment was not influenced by UV-A and naphthalene.