【摘要】 设置不同浓度的重金属Cd²⁺(0、0.2、0.4、0.6、0.8和1 mg·L^-1)和Pb²⁺(0、0.1、0.2、0. 4、0.8和1.6 mg·L^-1胁迫处理,检测米氏凯伦藻（Karenia mikimotoi）的生长生理情况,分析重金属胁迫对海洋微藻生长的毒性效应,探讨超氧化物歧化酶（SOD）和过氧化氢酶（CAT）等对重金属胁迫的缓解作用。研究结果发现,重金属Cd²⁺和Pb²⁺对米氏凯伦藻具有较强的毒性,随着重金属浓度的提高,细胞生长受到毒害作用增强;而米氏凯伦藻对重金属Cd²⁺和Pb²⁺胁迫具有一定的适应性。重金属Cd²⁺和Pb²⁺胁迫导致米氏凯伦藻细胞的叶绿素a、叶绿素b含量下降(1.6 mg·L^-1 Pb²⁺胁迫除外),类胡萝卜素含量提高,最大光能转化效率（F_v/F_m）下降,表明重金属胁迫抑制藻的光合作用,影响藻的生长繁殖。丙二醛（MDA）随着重金属Cd²⁺和Pb²⁺浓度提高而升高,说明重金属引起藻细胞膜透性增加,藻细胞遭受破坏。SOD活性整体呈现先升高后下降（或与对照持平）的趋势,提示海洋微藻的抗氧化酶系统在低浓度重金属胁迫下产生应激性反应,酶活性增强;而CAT活性上升,也对藻细胞起到保护作用,推测两者共同反应,以缓解藻体遭受的重金属毒害作用。结果可为了解重金属胁迫对海洋微藻的毒性效应提供参考。更多还原

【Abstract】 Marine microalga Karenia mikimotoi was treated by different concentrations of heavy metals Cd²⁺(0, 0.2, 0.4, 0.6,0.8 and 1 mg·L^-1) and Pb²⁺(0, 0.1, 0.2, 0.4, 0.8 and 1.6 mg·L^-1). Its physiological growth was detected to analyze the toxic effects of heavy metals on the growth of marine microalga. Besides, the effect of superoxide dismutase（SOD） and catalase（CAT） alleviating the toxicity of heavy metals on growth of microalga was discussed. The results showed that heavy metals Cd²⁺ and Pb²⁺ had strong toxicity to the growth of K. mikimotoi. With the increase of heavy metals concentration, the inhibited effect on the cell growth was increased. K. mikimotoi showed certain adaptability to heavy metals Cd²⁺ and Pb²⁺.The stress of Cd²⁺ and Pb²⁺ resulted in the decrease of chlorophyll a and chlorophyll b(except for 1.6 mg·L^-1 Pb²⁺), the increase of carotenoids, and the decrease of maximal photochemical efficiency（F_v/F_m）, which indicated that heavy metals inhibited the photosynthesis of K. mikimotoi. Malondialdehyde（MDA） increased with the increase of Cd²⁺ and Pb²⁺concentrations, demonstrating that heavy metals increased the permeability of algae cell membrane and destroyed algal cells.The SOD activity increased first and then decreased（or remained the same level as the control）, suggesting that the antioxidant enzyme system of marine microalga was activated under low concentration of heavy metals, hence enzymatic activity increased. Similarly, the increase of CAT activity also implied a protective role on algal cells. It is speculated that the SOD and CAT together can alleviate the toxic effects of heavy metals on algae. The results can provide a reference for understanding the toxic effects of heavy metal stress on marine microalgae.更多还原