N-苯基-2-萘胺对拟柱胞藻生长、抗氧化酶及光合系统Ⅱ的影响

EFFECT OF N-PHENYL-2-NAPHTHYLAMINE ON THE GROWTH, ANTIOXIDATIVE ENZYME AND PSⅡIN CYLINDROSPERMOPSIS RACIBORSKII

为探究化感物质对入侵水华蓝藻-拟柱胞藻(Cylindrospermopsis raciborskii)的影响,研究对不同浓度(0、0.05、0.10、0.50、1.00和2.00 mg/L)N-苯基-2-萘胺处理下拟柱胞藻的生长、抗氧化酶活性及叶绿素荧光诱导动力学进行了测定。结果表明,藻叶绿素a含量随N-苯基-2-萘胺浓度升高而显著降低,浓度大于0.50 mg/L时,拟柱胞藻叶绿素a含量显著低于对照。72h,N-苯基-2-萘胺对拟柱胞藻的EC50为1.02 mg/L。叶绿素荧光诱导动力学参数表明,浓度小于0.50 mg/L时,拟柱胞藻的最大光化学效率(φP0)、单位面积上有活性的反应中心(RC/CS0)、以吸收光能为基础的性能指数(PIABS)及以单位面积为基础的性能指数(PICS)均显著高于对照,而反映2ms时有活性的反应中心的开放程度的ψ0则显著低于对照组。当N-苯基-2-萘胺浓度大于0.50 mg/L时,以上参数均呈现相反趋势。这表明低浓度N-苯基-2-萘胺能提高拟柱胞藻的光合效率,而在高浓度时,拟柱胞藻PSⅡ有活性的反应中心减少,电子传递受到阻碍,光合效率下降。与对照相比,在浓度高于0.50 mg/L条件下,拟柱胞藻的过氧化氢酶(CAT)、过氧化物酶(SOD)及谷胱甘肽过氧化物酶(GPX)的活性显著增加,表明拟柱胞藻能产生大量的抗氧化酶来减少N-苯基-2-萘胺的损伤。这些结果表明N-苯基-2-萘胺可能通过抑制PSⅡ的电子传递和减少其有活性的反应中心来影响拟柱胞藻的生长,也暗示了N-苯基-2-萘胺能作为潜在的抑藻物质来控制拟柱胞藻水华。

In this study, we investigated the effects of N-phenyl-2-naphthylamine, a type of allelochemical, on the invasive cyanobacteria Cylindrospermopsis raciborskii. We measured the growth, the activities of antioxidative enzymes, and polyphasic Chl. a fluorescence transients of Cylindrospermopsis raciborskii that was cultured in the presence of N-phenyl-2-naphthylamine at different concentrations（0, 0.05, 0.10, 0.50, 1.00 and 2.00 mg/L）. When the concentration of N-phenyl-2-naphthylamine was higher than 0.50 mg/L, the Chl. a content was significantly lower than the control. This indicated that the level of Chl. a could be reduced by the increase in N-phenyl-2-naphthylamine. The EC50 of N-phenyl-2-naphthylamine on C. raciborskii was 1.02 mg/L after a 72 h exposure. At the concentration lower than 0.50 mg/L, N-phenyl-2-naphthylamine caused a significant increase in a variety of parameters of polyphasic Chl. a fluorescence transients, including the maximum quantum yield of primary photochemistry（φPo）, the density of RCs（RC/CSo）, the performance index on absorption basis（PIABS）, and the performance index on cross section basis（PICS）. One exception was ψo that declined in the presence of low concentration of N-phenyl-2-naphthylamine. On the other hand, φPo, RC/CSo, PIABS, PICS, and ψo were all reduced when the concentration of N-phenyl-2-naphthylamine was higher than 0.50 mg/L（eg. 1.00 mg/L and 2.00 mg/L）. These data suggested that low dose of N-phenyl-2-naphthylamine might promote the photosynthetic efficiency of C. raciborskii, while high dose could reduce density of RCs and harm the PS and electron transfer, and thus result in the inhibition of photosynthetic efficiencyⅡ in C. raciborskii. Compared to the control, the activities of superoxide dismutase（SOD）, catalase（CAT） and glutathione peroxidase（GPX） were all obviously elevated along with the increase in N-phenyl-2-naphthylamine concentration. This implied that C. raciborskii might counter the damage of N-phenyl-2-naphthylamine with enhanced antioxidant enzymatic activities. In conclusion, N-phenyl-2-naphthylamine could inhibit the growth of C. raciborskii by disrupting the electron transfer of PS Ⅱand lowering the density of RCs, and therefore it could be considered as a potential compound for the control of Cylindrospermopsis blooming.