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首页> 外文期刊>Environmental toxicology and chemistry >EFFECTS OF CHLORPYRIFOS ON THE CATALYTIC EFFICIENCY AND EXPRESSION LEVEL OF ACETYLCHOLINESTERASES IN THE BIVALVE MOLLUSK SCAPHARCA INAEQUIVALVIS
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EFFECTS OF CHLORPYRIFOS ON THE CATALYTIC EFFICIENCY AND EXPRESSION LEVEL OF ACETYLCHOLINESTERASES IN THE BIVALVE MOLLUSK SCAPHARCA INAEQUIVALVIS

机译：氯氟酸对双壳软体动物头孢虫中乙酰胆碱酯酶的催化效率和表达水平的影响

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Three acetylcholinesterase (AChE) forms were detected and recovered from foot or gill tissues of the benthonic bivalve mollusk Scapharca inaequivalvis. A study was performed to investigate changes in catalytic and hydrodynamic features of these enzymes, as well as in their expression levels, after a 4-d or a 15-d exposure to a sublethal concentration (0.1 μl/L) of the pesticide chlorpyrifos (CPF). Both considered organs hold, in either CPF-exposed or untreated animals, two nonamphiphilic AChE forms, G_2 and G_4, which copurified on a procainamide-containing affinity gel and were separated by density gradient centrifugation. A third AChE form, an amphiphilic membrane-anchored G_2, was also purified on the same affinity matrix from both organs. All enzymatic forms are true AChEs and are poorly inhibited by CPF. They show different increases in the maximum velocity (V_(max)) and in the Michaelis constant (K_m) values after CPF exposure. Consequently, catalytic efficiency of AChEs, as defined by the ratio V_(max):K_m, rises in the gills and drops in the foot. This would produce an overexpression of AChE-specific mRNAs. The effect was longer lasting in the foot. The combined results indicate that overexpression of enzymes in the presence of organophosphate (OP) may be a consequence of OP resistance itself. Again, the resistance of the organism to CPF seem to depend mainly on the resulting increase in AChE content.
机译：从底栖双壳软体动物Scapharca inaequivalvis的足或g组织中检测到三种乙酰胆碱酯酶（AChE）形式并从中回收。进行了一项研究以研究这些酶在毒死浓度（0.1μl/ L）的亚致死浓度（0.1μl/ L）中暴露4天或15天后这些酶的催化和流体动力学特征及其表达水平的变化（ CPF）。在CPF暴露或未经处理的动物中，两个被认为的器官均具有两种非两亲性的AChE形式G_2和G_4，它们在含普鲁卡因酰胺的亲和凝胶上共纯化，并通过密度梯度离心法分离。还从两个器官的相同亲和基质上纯化了第三种AChE形式，即两亲性膜锚定的G_2。所有的酶形式都是真正的AChEs，CPF抑制能力很差。它们显示出在CPF暴露后最大速度（V_（max））和米氏常数（K_m）值的不同增加。因此，由比率V_（max）：K_m定义的AChEs的催化效率在g处上升而在脚部下降。这将产生AChE特异性mRNA的过表达。效果在脚上持续更长时间。综合结果表明，在有机磷酸酯（OP）存在下酶的过表达可能是OP抗性本身的结果。同样，生物体对CPF的抗药性似乎主要取决于所导致的AChE含量的增加。

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