Hg2+对南极冰藻Chlorophyceae L-4生长和抗氧化系统的影响及藻体富集Hg2+的规律

Influence of Hg2+on the growth and the antioxidant system of an Antarctic algae Chlorophyceae L-4 and the feature of its accumulating Hg2+

摘要:

南极冰藻Chlorophyceae L-4是南极生态系统重要的初级生产力和组成部分，其长期生长在极地环境中，有着特殊的生理机制。在生存环境和生长条件发生变化时，冰藻的膜脂系统和蛋白含量都会发生变化，而在受到重金属胁迫时，冰藻的超微结构也会发生明显变化。【目的】研究Chlorophyceae L-4在重金属离子Hg2+胁迫条件下的状态和Hg2+富集以及对其抗氧化系统的影响，为南极环境监测提供依据。【方法】绘制南极冰藻细胞在重金属离子Hg2+不同浓度胁迫条件下的生长曲线，观察其超微结构；测定丙二醛含量和SOD酶活性变化；ICP-MS法研究藻体富集Hg2+规律。【结果】Hg2+在低浓度时(≤100 μg/L)，细胞个数较正常条件明显偏少；在高浓度时(≥250 μg/L)，出现细胞死亡。丙二醛含量随Hg2+浓度升高而升高，SOD酶活性则先增强再减弱。藻体富集Hg2+在1 h达到峰值，而在Hg2+浓度持续升高时，富集量轻微降低。【结论】Hg2+离子对冰藻生长有抑制毒害作用；对Chlorophyceae L-4抗氧化系统有明显不利影响；L-4富集Hg2+在1 h内饱和，Hg2+过高时，富集量稍微降低。

Abstract:

Antarctic ice algae Chlorophyceae L-4 is an important component and primary productivity of Antarctic ecosystem. It has specific physiological mechanism for longtime survival in the polar environment. When living environment and conditions get change, membrane-lipid system and protein level varies. Ultrastructure of ice algae also changes under heavy metal stress. [Objective] To observe Chlorophyceae L-4 state under Hg2+ stress, and study Hg2+ enrichment and influence on antioxidant system of Chlorophyceae L-4. Then provide theoretical foundation for Antarctic environmental monitoring. [Methods] Drew growth curve of Antarctic algae in different concentration stress conditions of Hg2+and algae ultrastructure observation. Measured MDA content and SOD enzyme activity. Detected Hg2+ enrichment rule by ICP-MS. [Results] Cell count decreased in lower Hg2+ concentration (≤100 μg/L), and in higher concentration (≥250 μg/L), algae cells died. MDA content increases as Hg2+ concentration increased. SOD enzyme activity was enhanced at first and then decreased. Hg2+ enrichment reaches a peak value within one hour and after that, enrichment value reduced slightly. [Conclusion] Hg2+ would be inhibiting and poisonous to the growth of algae. Hg2+ has obvious adverse influence on Chlorophyceae L-4 antioxidant system. Hg2+ absorption of L-4 reach saturation in one hour. Enrichment amount of Hg2+ decreased slightly when it is over concentrated.