光强对两种硅藻光合作用、碳酸酐酶和RubisCO活性的影响

为研究海洋浮游硅藻光合固碳能力与光强的关系, 以三角褐指藻和威氏海链藻为实验材料, 测定了不同光强培养下三角褐指藻和威氏海链藻生长、光合特性、碳酸酐酶和核酮糖-1, 5-二磷酸羧化/氧化酶活性(RubisCO)的变化, 结果显示高光强促进两种硅藻的生长, 但对威氏海链藻的影响更明显。高光强导致两种硅藻叶绿素a、c含量、光系统Ⅱ的最大光化学效率和实际光化学效率明显下降, 非光化学淬灭系数明显升高, 但对光化学淬灭系数并没有明显影响。在高光下威氏海链藻和三角褐指藻胞内外碳酸酐酶活性明显升高。在高光强下培养的威氏海链藻RubisCO活性明显高于低光下培养, 但三角褐指藻正好相反, 不管高光还是低光培养威氏海链藻RubisCO活性始终高于三角褐指藻。以上结果表明不同硅藻对光强变化的响应存在差异, 它们可以通过调节光合生理特征、光合固碳关键酶和CO2供应以适应光强的变化。  

EFFECTS OF LIGHT INTENSITIES ON PHOTOSYNTHESIS,CARBONIC ANHYDRASE AND RUBISCO ACTIVITY IN TWO DIATOMS

Marine planktonic diatoms play an important role in marine primary productivity and the carbon fixation is closely related to light intensity. In the present study, we investigated the growth rate, photosynthetic characteristics, carbonic anhydrase activity, and ribulose 1, 5-bisphosphate carboxylase/oxidase (RubisCO) activity of Phaeodactylum tricornutum and Thalassiosira weissflogii under different light intensities (high or low light). The results showed that high light intensity promote the growth of the two diatoms, which was more obvious in T. weissflogii. High light intensity attenuated the levels of chlorophyll a, c content, Fv/Fm and Yield but increased qN. High light intensity has no effect on qP. High light also enhanced the intracellular and extracellular carbonic anhydrase activities in both diatoms. Interestingly, in P. tricornutum, low light increased ribulose-1,5-bisphosphate carboxylase/oxygenase activity compared to high light; however, the opposite result was observed in T. weissflogii. Rubisco activity in T. weissflogii is higher than that in P. tricornutum in.both low and high light. These results suggest that the two diatoms are differently responded to the light intensity and that they can accordingly adjust their photosynthetic characteristics, carbonic anhydrase and RubisCO activity to accommodate the varied light intensity.