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首页> 外文期刊>Environmental toxicology and chemistry >FAILURE OF THE BIOTIC LIGAND AND FREE-ION ACTIVITY MODELS TO EXPLAIN ZINC BIOACCUMULATION BY CHLORELLA KESSLERII
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FAILURE OF THE BIOTIC LIGAND AND FREE-ION ACTIVITY MODELS TO EXPLAIN ZINC BIOACCUMULATION BY CHLORELLA KESSLERII

机译：生物配体的破坏和游离离子模型无法解释叶绿素（Klolerla Kesslerii）的锌生物富集

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摘要

Zinc accumulation by Chlorella kesslerii (Chlorophycee) was studied for [Zn~(2+)] ranging from 4 pM to 1 mM. A first-order uptake flux as predicted by the free ion activity model (FIAM) and the biotic ligand model (BLM) was not observed. Furthermore, when algae were preconditioned in slightly limiting (10 pM) versus optimal (1 nM) free zinc concentrations, the intcrnalizution flux increased and was nearly constant over the range of [Zn~(2+)] examined. This observation was attributed to the synthesis of membrane-bound zinc transporters. Neither solution Zn chemistry nor surface-bound Zn was a good predictor of Zn uptake fluxes. Several hypotheses were examined to explain the failure of the steady-state uptake models. Although zinc excretion and a Zn diffusion limitation were observed, neither result could explain the majority of observed deviation from the models. Biliac-cumulation experiments performed with inhibitors (vanadate and carbonyl cyanide m-chlorophenylhydrazone [CCCP]) demonstrated clearly that zinc transport is an energy-dependent process in Chlorella kesslerii. The presence of an active transport signifies that Zn uptake may function independently of the electrochemical Zn gradient and that, in some cases, both uptake fluxes and receptor-bound Zn may be independent of solution chemistry.
机译：研究了凯氏小球藻（Chlorophycee）对锌的累积，其[Zn〜（2+）]范围为4 pM至1 mM。没有观察到由自由离子活性模型（FIAM）和生物配体模型（BLM）预测的一级吸收通量。此外，当藻类在相对于最佳（1 nM）的游离锌浓度略有限制（10 pM）的条件下进行预处理时，浸入通量增加，并且在[Zn〜（2+）]范围内几乎恒定。该观察结果归因于膜结合锌转运蛋白的合成。溶液锌的化学性质和表面结合的锌都不能很好地预测锌的吸收通量。研究了几种假设以解释稳态吸收模型的失败。尽管观察到锌排泄和锌扩散限制，但这两个结果都不能解释模型中观察到的大部分偏差。用抑制剂（钒酸盐和羰基氰化物间氯苯基hydr [CCCP]）进行的胆汁累积实验清楚地表明，锌的运输是凯斯小球藻中能量依赖的过程。活性转运体的存在表明锌的吸收可能独立于电化学Zn梯度起作用，并且在某些情况下，吸收通量和受体结合的Zn可能与溶液化学性质无关。

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