底栖硅藻新月筒柱藻对锌胁迫的生理学效应

The Toxic Effects of Zinc on a Benthic Diatom Cylindrotheca closterium

采用流式细胞仪检测细胞增长与色素含量、原子火焰吸收光谱法测定金属含量以及显微镜观察细胞状态等方法研究了红树林底栖硅藻新月筒柱藻(Cylindrotheca closterium(Ehr.)Re im ann and Lew in)暴露在重金属锌96 h内的细胞增长、光合色素含量和细胞形态结构等胁迫效应,以及锌在藻细胞内外动态分布的情况.结果为:(1)在Zn2+浓度小于10mg/L范围内,锌对新月筒柱藻的细胞增长和色素含量均无显著抑制作用.(2)1 mg/L和10 mg/L的Zn2+对藻细胞内的叶黄素和叶绿素a的产生都有促进作用.(3)在实验开始的24 h内,藻细胞处在低Zn2+浓度(1 mg/L)时,藻细胞胞内吸收的Zn2+大于胞外吸附的Zn2+.而藻细胞处在高Zn2+浓度(10 mg/L)时,胞外吸附的Zn2+较胞内吸收的大,细胞内Zn2+的含量处在较低水平,从而促进细胞的增长和色素的合成并使细胞免受外界高浓度锌的毒害.可见,新月筒柱藻正是通过改变对锌的富集方式,以保持细胞内锌含量的相对稳定来适应不同浓度锌的胁迫.

The toxic effects of zinc on the cell division, pigment content, and cell morphology of Cylindrotheca closterium, a benthic diatom commonly occurring in the mangrove soil, were investigated. The distribution pattern of zinc in algal cells was also studied. The flow cytometer, atomic absorption sepectrometr and microscope were used in this article. The results showed： 1） when the concentration of zinc was below 10 mg/L, there was no significant negative effect on cell division or pigment content. 2） 1 mg/L and 10 mg/L zinc ion improved lutein and chlorophyll a content in algal cell. 3） In the first 24 hours of the culture experiment, the algal cells of 1 mg/L zinc ion group had higher intracellular absorption of zinc, and the algal cells of 10 mg/L group had higher attached absorption of zinc. Remaining low concentration of intracellular zinc ion improved cell division and pigment content when the cells were cultured in 10 mg/L zinc ion solution. So C. closterium could avoid the zinc toxicity by changing the absorption way of zinc ion to remain low concentration of intracellular zinc ion when the cells under the zinc stress.