Acute toxicity of excess Cu on the photosynthetic performance of Chlorella pyrenoidosa was examined by using chlorophyll a fluorescence transients and JIP-test after exposure to elevated Cu concentrations for a short time period. High Cu concentration resulted in a significant suppression in photosynthesis and respiration. The absorption flux （ABS/RC） per PSII reaction center increased with increasing Cu concentration, but the electron transport flux （ET0/RC） decreased. Excess Cu had an insignificant effect on the trapping flux （TR0/RC）. The decline in the efficiency, with which a trapped exciton can move an electron into the electron transport chain further than QA-（Ψ0）, the maximal quantum yield of primary photochemistry （φP0）, and the quantum yield of electron transport （φE0） were also observed. The amount of active PSII reaction centers per excited cross section （RC/CS） was also in consistency with the change of photosynthesis when cells were exposed to excess Cu concentration. JIP-test parameters had a good linear relationship with photosynthetic O2 evolution. These results suggested that the decrease of photosynthesis in exposure to excess Cu may be a result of the inactivation of PSII reaction centers and the inhibition of electron transport in the acceptor side.
以赤潮硅藻小新月菱形藻(Nitzschia closterium var. minutissima)为实验材料,研究了短期内(12h)高浓度CO2(5%CO2)对其胞外碳酸酐酶活性和光合作用的影响,结果显示,高浓度CO2培养导致小新月菱形藻胞外碳酸酐酶活性、叶绿素a和叶绿素c含量明显下降.与通空气培养(0.035%CO2)相比,在短期内(12h)胞外碳酸酐酶活性下降了75.4%,叶绿素a、c含量分别降低了5.6%和7.3%;高浓度CO2培养下最大光化学效率(Fv/Fm)、实际光化学效率(Yield)和光化学淬灭系数(qP)下降,但非光化学淬灭系数(qN)升高.研究结果表明,高浓度CO2对胞外碳酸酐酶活性具有明显的抑制作用,小新月菱形藻通过调整光系统II的能量流动和能量利用效率以适应高浓度CO2的环境.
Bangia fusco-purpurea,an economic macroalgae,was often cultivated in Zhejiang and Fujian coastal areas.Its cultivation in Guangdong coast and photosynthetic characteristics had not been well documented.In this paper it was transplanted from Fujian Province to the sea area of Nan′ao Island in Guangdong Province,and the photosynthetic characteristics and fatty acids compoment were investigated by using photosynthetic gas exchange and gas chromatography.The results showed that Bangia fusco-purpurea grew well in situ with a higher photosynthetic light saturation point of 210 μmol/(m2·s).The lower light compensation point as well as dark respiration rate were also observed.The polyunsaturated fatty acids(PUFAs) accounted for more than half of the total fatty acids.The eicosapentaenoic acid(EPA) content was 41.20% in the total fatty acids,and reached as high as 499.82 mg per 100 g dry weight,which was significantly higher than that of Porphyra haitanensis or Gracilaria lemaneiformis grown in the same sea area.In conclusion,it was practicable that Bangia fusco-purpurea was cultivated in the sea area of Nan′ao Island.The algae could be exploited as a new source of EPA production because of its higher EPA content.
