Cu和Cd联合胁迫对海草泰来藻体内Cd的亚细胞分布的影响及其生态学意义  

Subcellular distribution of cadmium in seagrass Thalassia hemprichii and its ecological significance under coupled stress of copper and cadmium

作　　者：冯韶辉[1,2] 黄小平[1] 张景平[1] 

机构地区：[1]中国科学院南海海洋研究所热带海洋环境国家重点实验室,广东广州510301 [2]中国科学院研究生院,北京100049

出　　处：《海洋环境科学》2013年第3期321-326,共6页Marine Environmental Science

基　　金：国家自然科学基金项目(41076069;40776086);南海区海草床环境质量综合评价方法[DOMEP-(MEA)-01-03]

摘　　要：利用差速离心法研究了Cu和Cd联合胁迫下热带海草泰来藻(Thalassia hemprichii)体内Cd的亚细胞分布,并分析了该联合胁迫对Cd的亚细胞分布的影响及其生态学意义。结果表明,在Cu和Cd联合胁迫下,叶是泰来藻累积Cd的主要部位,且根和叶中细胞溶质部分的Cd始终占据绝对优势,其比例为65%～94%,说明细胞溶质部分是Cd在泰来藻体内的主要分布位点,这种分布特性可能会增强海草Cd的动物可利用性。泰来藻叶和根及其各亚细胞组分的Cd含量具有显著的Cu和Cd浓度依赖性(P<0.05)。三种浓度的Cd(0.001 mg/L、0.01 mg/L和0.1 mg/L)分别与低浓度Cu(0.1 mg/L)的复合处理下,泰来藻长势依然良好,但使叶和根对Cd的累积量显著增加,且Cd在亚细胞的分布显示出细胞壁上的分配比例显著增加的趋势,这种分配特性可能会增大Cd在碎屑食物链上传递效率。另一方面,同样三种浓度的Cd与高浓度Cu(1.0mg/L)的复合处理下,泰来藻根和叶各亚细胞组分对Cd的累积量明显低于Cd与低浓度Cu的复合处理,但Cd在叶绿体上的分配比例却显著增加,这是致使泰来藻衰亡的主要原因。本研究首次分析了重金属的联合胁迫对泰来藻根和叶中Cd的亚细胞分布的影响,发现不同金属浓度的联合胁迫可改变Cd在泰来藻根和叶的亚细胞分布,可为Cd在海洋食物链上的传递研究提供基础支撑。Subcellular distribution of Cd in seagrass Thalassia hemprichii under coupled stress of Cu and Cd was investigated using the differential centrifugation technique.Cd was mainly accumulated in leaves and 65% ~94% of Cd was distributed in soluble fraction of root or leave under all the treatments,suggesting that the soluble fraction is the main storage site for Cd in seagrass T.hemprichii,which might enhance bioavailability of Cd from seagrass in marine food chains.A significant Cu and Cd-concentration-dependent effect of the content of Cd in various subcellular fractions and/or different tissues was observed under Cu and Cd coupled stresses.Under coupled stresses of Cd and low Cu level（0.1 mg/L）,the content of Cd in seagrass increased significantly,accompanying an increasing in percentage of cytoderm-containing fraction,which might enhance the transfer efficiency of Cd in marine detritus food chains.On the contrary,under coupled stress of Cd and high Cu level（1.0 mg/L）,the content of Cd in various subcellular fractions significantly lower than those under the coupled stresses of Cd and low Cu level.However,the percentage of choloplast-containing fraction increased remarkably,which might be one of the important reasons causing seagrass＇s death.It is the first time we study the subcellular distribution of Cd in seagrass T.hemprichii under coupled metal stress,which could be suggested that the difference in toxicity under diverse coupled stress of Cd and Cu will change the subcellular distribugion of Cd in leave and root of T.hemprichii.

关 键 词：镉 铜 联合胁迫 泰来藻 亚细胞分布 累积 

分 类 号：Q945.78[生物学—植物学]