多氯联苯(PCB_(153))对湛江叉鞭金藻生理生态和超微结构的影响

Effects of Polychlorinated Biphenyls(PCB)on the Physiological Ecology and Ultrastructure of Dicrateria zhanjiangensis

为研究多氯联苯对海洋微藻的生理生态毒性,以湛江叉鞭金藻(Dicrateria zhanjiangensis)为研究对象,进行7d的六氯联苯(PCB_(153))胁迫实验,比较其生长、光合色素含量、谷胱甘肽S-转移酶(GST)、超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量以及藻细胞超微结构的变化情况。结果显示,PCB_(153)胁迫对湛江叉鞭金藻的生长、光合色素含量及抗氧化和解毒相关指标均有显著影响(P<0.05)。随着PCB_(153)浓度的增大,其对湛江叉鞭金藻生长抑制作用不断增大,250μg/L胁迫组藻细胞在第5天全部死亡。PCB_(153)胁迫后,湛江叉鞭金藻叶绿素a、叶绿素c、类胡萝卜素和总光合色素均显著下降(P<0.05),且随着PCB_(153)浓度的增加,各实验组光合色素含量下降比例增大。PCB_(153)胁迫后,各胁迫组藻细胞MDA含量显著增加;低浓度PCB_(153)(<25μg/L)胁迫显著诱导SOD和GST活性的提高;而高浓度PCB_(153)(>25μg/L)胁迫则显著抑制2种酶活性。短期低浓度PCB_(153)胁迫会改变金藻细胞超微结构,使细胞器形态改变、聚缩;高浓度PCB_(153)胁迫则会直接破坏细胞膜的完整性,使细胞破裂,导致细胞自溶死亡。研究表明,PCB_(153)抑制叉鞭金藻的生长和光合色素合成,低浓度PCB_(153)激活抗氧化和解毒系统,提高其自我保护水平,高浓度PCB_(153)加剧脂质过氧化,破坏抗氧化和解毒系统正常功能,导致细胞破裂死亡。

In order to study the physiological and ecological toxicity of polychlorinated biphenyls(PCBs)of marine microalgae,the growth,photosynthetic pigment content,glutathione S-transferase(GST),superoxide dismutase(SOD)activity,malondialdehyde(MDA)content,and ultrastructure of Dicrateria zhanjiangensis were compared over 7 days under 2,2?,4,4?,5,5?-hexachlorobiphenyl(PCB_(153))stress.The results showed that PCB_(153)stress had significant effects on the growth,photosynthetic pigment content,antioxidant and detoxification related indexes of D.zhanjiangensis(P<0.05).Increasing PCB_(153)concentration increased the inhibition of PCB_(153)on the growth of D.zhanjiangensis.In the 250μg/L stress group,all the algae cells died on day five.The content of chlorophyll a,chlorophyll c,carotenoid,total light,and pigment had decreased significantly after the PCB_(153)stress(P<0.05).The decreasing photosynthetic pigment level was enhanced by the increase in PCB_(153)concentration.The MDA content of algal cells in all stress groups increased after the PCB_(153)stress.SOD and GST enzyme activities were significantly increased by low concentration PCB_(153)(<25μg/L).Both enzyme activities were significantly inhibited by high concentrations of PCB_(153)(>25μg/L).Under short-term low concentrations of PCB_(153)stress,the ultrastructure of the cells changed.To be specific,the organelle morphology altered and shrunk.Under high concentrations of PCB_(153)stress,the integrity of the cell membrane was destroyed,leading to cell rupture,autolysis and death.PCB_(153)can inhibit the growth and synthesis of photosynthetic pigments of D.zhanjiangensis.Low concentrations of PCB_(153)can activate the antioxidant and detoxification system.This activation improves self-protection capabilities.High concentrations of PCB_(153)can aggravate lipid peroxidation and destroy the normal function of antioxidant and detoxification systems,causing cell rupture and death.