镉在黑藻叶细胞中的亚显微定位分布及毒害效应分析  

DISTRIBUTION AND TOXICITY OF CADMIUM IN HYDRILLA VERTICILLATA(L.F.)ROYLE

作　　者：徐勤松[1] 施国新[1] 周耀明[2] 吴国荣[1] 王学[1] 

机构地区：[1]南京师范大学生命科学学院,南京210097 [2]南京师范大学化学与环境科学学院,南京210097

出　　处：《实验生物学报》2004年第6期461-468,共8页Acta Biologiae Experimentalis Sinica

基　　金：国家自然科学基金(30370083);教育部科学技术研究重点项目(01043);江苏省教育厅自然科学基金(03KJB180062);江苏省重点实验室开放基金。

摘　　要：水生植物被认为能积累和浓缩重金属,本文以不同浓度Cd培养7天的黑藻为材料,研究了Cd的积累,亚细胞分布,亚显微定位,存在形态及对矿质营养吸收,光合速率和呼吸速率的影响,以揭示Cd的植物毒害机理。研究结果表明,随培养液中Cd浓度的增加,植株体内的Cd含量显著上升,富集系数为193-307;不同亚细胞组份中的Cd含量也都呈上升趋势,但分布显著不均,分配顺序依次为细胞壁>可溶性部分>细胞器,其中,积累在细胞壁中的含量所占比例呈下降趋势(61.66%-52.00%),而可溶性部分中则递增,细胞器部分结合的Cd含量所占比例相对恒定;硫化物-银法定位结果直观显示出Cd分布在细胞壁、叶绿体、细胞核和液泡中;逐步提取法分析表明受Cd毒害的黑藻体内Cd以不同化学形态存在,其中Nacl提取态占比例最大(55.05%),其他则较少,依次为F_(NaCl)>F_(HAc)>F(Water)>F(Ethanol)>F(HCl)>F(Residue);Cd对黑藻的营养元素吸收也产生影响,主要是促进对Ca,Mn,Cu,Fe的吸收,降低对大量元素P,K的吸收;Cd对黑藻的光合速率和呼吸速率都有较强的抑制作用。结果表明Cd毒害与处理浓度间存在显著的剂量一效应关系;亚细胞分布与对细胞超微结构的损伤关系密切;Cd破坏了黑藻正常生理活动的结构基础和离子平衡,并造成功能紊乱。这些都是Cd对植物产生毒害的重要原因。Aquatic plants are known to accumulate and bioeoncentrate heavy metals.In this study, aquatic vascular plant Hydrilla verticillata(L.f.)Royle was cuhivated in water containing elevated con- centrations of cadmium(up to 10mg/L) for 7d,the accumulation,subeellular distribution,ultrastructural localization,chemical form,toxie effects on mineral nutrient absorption of cadmium,photosynthesis rate and respiration rate were studied.It was found that H.verticillata fronds was able to accumulate cadmi- um,the bioconeentration factor was 193-307;subcellular fraction analysis revealed that cadmium major accumulated in cell wall(61.66%-52.00%) with decrease trends,the content of Cd enhanced in soluble fraction and remained stable in organelles,with the augment of pollutant concentration.The Cd levels occurred in different parts of leaf cell with the following sequence:cell wall>soluble fraction>or- ganelles.Uhrastruetural localization of cadmium with sulfide-silver method showed that Cd appeared in cell wall,chloroplast,nucleus and vacuole.Sequential extraction indicated that the ratio of different cadmium chemical form was different markedly,of which NaCl extractable Cd was predominated as compared with the other 5 forms;which could be seen in the following order:F_(NaCl)>F_(HAe)>F_(Water)>F_(Ethanol)>F_(HCl)> F_(Residue).The mineral nutrient absorption was also affected by cadmium stress,it increased the absorption of Ca,Mn,Cu,and Fe;but reduced that of P and K.Cd had a strong inhibitive effect on photosynthe- sis rate and respiration rate.The results suggested that the toxic symptoms of plant showed an evident correlation between dose and effect;the uhrastruetural damage was closely related to the distribution of Cd.The conclusion could be reached that the death of plant was resulted from destruction of structure foundation of physiological function,unbalance of ion equilibrium and disorder of physiological metabolism.

关 键 词：黑藻 毒害 光合速率 呼吸速率 吸收 细胞壁 浓度 显微 含量 体内 

分 类 号：X173[环境科学与工程—环境科学]