17α-炔雌醇对三角褐指藻的毒性效应研究

Toxic effects of 17α-ethinylestradiol on Phaeodactylum tricornutum

以三角褐指藻(Phaeodactylum tricornutum)为受试藻种,分析了5种浓度17α-炔雌醇(EE2)(0.375,0.75,1.5,3,6mg/L)对其生长、表面形貌、光合色素含量、叶绿素荧光参数、抗氧化系统及细胞周期的影响.结果表明,EE2能抑制三角褐指藻的生长,对其具有较高毒性(96h-EC50=5.32mg/L).低浓度EE2(0~0.75mg/L)对三角褐指藻的光系统Ⅱ(PSⅡ)活性具有一定的促进作用.与对照组相比,EE2浓度达到6mg/L时,藻细胞表面形貌受损,光合色素含量及最大光量子产量(Fv/Fm)显著降低.光限制斜率(α)、最大相对电子传递速率(r ETRmax)和半饱和光强(Ik)也随之降低,其光系统Ⅱ(PSⅡ)活性受到抑制.此外,超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性及丙二醛(MDA)含量显著升高,细胞周期在DNA合成期(S)和分裂期(G2/M)发生阻滞,表明三角褐指藻的抗氧化系统产生应激反应.

The growth,surface morphology,photosynthetic pigment content,chlorophyll fluorescence parameters,antioxidant system and cell cycle of Phaeodactylum tricornutum in different concentrations of EE2(0.375,0.75,1.5,3,6mg/L)were determined.The results show that EE2 could inhibit the growth of Phaeodactylum tricornutum at the 96h-EC50 level of 5.32mg/L,suggesting that EE2 had high toxicity to Phaeodactylum tricornutum.Low concentration of EE2≤0.75mg/L promoted the photosystem II(PSII)activity of Phaeodactylum tricornutum;however,its surface morphology was damaged and its photosynthetic pigment content and maximal photochemical efficiency(Fv/Fm)were significantly reduced under EE2 concentration of 6mg/L.Meanwhile,the light limitation slope(α),the maximum electron transfer efficiency(rETRmax),and semi-saturated light intensity(Ik)also decreased.These results indicate that high concentration of EE2 inhibited the photosystem II(PSII)activity of Phaeodactylum tricornutum.In addition,the activities of both the superoxide dismutase(SOD)and catalase(CAT)and the malondialdehyde(MDA)content significantly increased under the high concentration of EE2,and the cell cycle was arrested in the DNA synthesis phase(S)and division phase(G2/M),demonstrating that a stress response was resulted from the antioxidant system of Phaeodactylum tricornutum.