龙须菜对重金属和有机物联合毒性的响应

在实验生态条件下,从生理生化特性及抗氧化防御等方面,研究龙须菜对镉(Cd)和邻苯二甲酸二甲酯(DMP)联合作用(以下用Cd/DMP表示)的胁迫响应.结果显示,龙须菜生长受Cd/DMP联合质量浓度和暴露时间的影响.当Cd和DMP质量浓度分别小于1.5 mg/L和0.2 mg/L时,叶绿素a(Chl.a)、藻红素(PE)及可溶性蛋白的质量分数与对照组比较无显著性差异(P>0.05), 硝酸还原酶(NR)、过氧化物酶(POD)及过氧化氢酶(CAT)活性短时间内以诱导为主;当Cd和DMP质量浓度分别超过1.5 mg/L和0.2 mg/L,尤其是Cd和DMP的质量浓度分别大于3.0 mg/L和0.4 mg/L时,Chl.a和PE质量分数随Cd/DMP质量浓度的升高和暴露时间的延长呈明显下降趋势(P<0.001), 而MDA呈明显上升趋势,NR、POD和CAT活性受到显著抑制,龙须菜生长受到明显抑制,藻体表现出发黄发白等表观性状.Chl.a 含量、CAT活性与Cd/DMP联合暴露质量浓度具有良好的时间效应和剂量效应关系,可作为龙须菜暴露于Cd和DMP环境中的标志.

Response of seaweed Gracilaria lemaneiformis to combined toxicities of heavy metal and organic substance

Effects of combined cadmium (Cd) and dimethyl phthalate (DMP) on the antioxidantivity of Gracilaria lemaneiformis and on the physicochemical features were studied under experimental and ecological conditions. Results showed that the growth of G. lemaneiformis was affected by changes in concentrations of Cd/DMP and in seaweed culture time. In comparison with the control, no significant difference was observed in the contents of chlorophyll a (Chl. a) , phycoerythrin and soluble protein (P >0. 05 in all cases). Activities of nitrate reductase, per-oxidase and catalase (CAT) were induced by short-time treatment with Cd/DMP at 1.5/0.2 mg/L. Contents of Chl. a and PE and activities of NR, POD and CAT markedly decreased in a concentration and exposure-time dependent manner after treatment with Cd/DMP exceeded 1. 5/0. 2 mg/L, especially at 3. 0/0. 4 mg/L ( P < 0. 001) , while propyldialdehyde content significantly increased. In addition, G. lemaneiformis showed decreased growth rate. A dosage and time response exists between Chl. a content or CAT activity and concentrations of Cd/ DMP, suggesting that Chl. a and CAT can be used as two indicator for biologically monitoring exposure of G. lemaneiformis to Cd and DMP.