摘要:
为探讨生物配体模型(BLM)对金属混合物的适用性,以莱茵衣藻(Chlamydomonas reinhardtii)为研究对象,以藻体内短时间(≤ 60 min)生物积累量为指标,研究了Pb和Cd对莱茵衣藻的联合毒性作用。结果表明:Pb和Cd单独暴露下,藻体内生物积累过程可用米门方程(Michaelis-Menten equation)来描述。计算得到Cd传输位点的最大吸收通量Jmax为(8.312±0.034)×10-12mol·cm-2·s-1,该位点的半饱和系数(米门系数)KM=(1.012±0.032)×10-6mol·L-1,稳定常数KCd=0.988×106(mol·L-1)-1;Pb传输位点的Jmax为(1.28±0.039)×10-11mol·cm-2·s-1,该位点的KM=(3.56±0.34)×10-7mol·L-1,KPb为2.81×106(mol·L-1)-1。Cd和Pb的竞争实验中,当固定Cd的浓度,其吸收通量随Pb的增加而显著降低;固定Pb的浓度,其吸收通量随Cd的增加略有降低。这表明Pb和Cd可能存在相同的传输位点,且Pb对传输位点的结合能力要远大于Cd。在低浓度Pb和Cd的混合暴露溶液中,短时间内绿藻对Pb的生物积累量会远大于Cd。研究结果表明BLM可用于描述低浓度下Cd和Pb的竞争关系。
Abstract:
In order to explore the applicability of biotic ligand model(BLM) to metal mixture,Chlamydomonas reinhardtii was chosen as a testing organism,and the bioaccumulation was used as the index to investigate the joint toxic effects of Cd and Pb. The results indicated that for the individual Cd or Pb exposure,Cd bio-uptake was well described by a Michaelis-Menten equation with the constants:Jmax=(8.312 ±0.034)×10-12 mol·cm-2·s-1,KM=(1.012 ±0.032)×10-6 mol·L-1,KCd=0.988×106 (mol·L-1)-1; Pb bio-uptake was described by the equation with the constants:Jmax=(1.28 ±0.039)×10-11 mol·cm-2·s-1,KM=(3.56 ±0.34)×10-7 mol·L-1,KPb=2.81×106 (mol·L-1)-1. In the competition experiment of Cd and Pb,we found that the maximum influx rate(Jmax) of Cd(Pb) de-creased with the increase of Pb(Cd) concentration,and the competition between Pb and Cd can be described by BLM.The results suggested that Cd and Pb were likely to share a common bio-uptake pathway,and in a short period(≤ 60min),the combination ability of Pb to bio-uptake pathway was greater than Cd in the low mixed solution of Pb and Cd.
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