Interspecies-Extrapolated Biotic Ligand Model to Predict Arsenate Toxicity to Terrestrial Plants with Consideration of Cell Membrane Surface Electrical Potential.

Jinsung An

doi:10.3390/toxics10020078

Abstract

Arsenic is a metalloid that is highly toxic to living organisms in the environment. In this study, toxicity caused by inorganic arsenate (As(V)) to terrestrial plants, such as barley Hordeum vulgare and wheat Triticum aestivum, was predicted using the existing biotic ligand model (BLM) for bioluminescent Aliivibrio fischeri via interspecies extrapolation. Concurrently, the concept of cell plasma membrane electrical potential (Ψ0) was incorporated into the extrapolated BLM to improve the model predictability in the presence of major cations such as Ca2+. The 50% effective As(V) toxicity (EC50{HAsO42−}) to H. vulgare decreased from 45.1 ± 4.34 to 15.0 ± 2.60 µM as Ca2+ concentration increased from 0.2 to 20 mM owing to the accumulation of H2AsO4− and HAsO42− on the cell membrane surface. The extrapolated BLM, which only considered inherent sensitivity, explained well the alteration of As(V) toxicity to H. vulgare and T. aestivum by Ca2+ with in an order of magnitude, when considering a linear relationship between Ψ0 and EC50{HAsO42−}.

Highlights

Consideration of Cell MembraneArsenic (As) accumulates in environmental media via both natural and anthropogenic sources and can cause severe adverse effects on human health as well as ecosystems [1–5].Because the total As concentration in the environmental media cannot accurately indicate bioavailability or ecotoxicity, it is important to rationally assess the ecotoxicity of As using suitable bioassays [6]
The aim of this study was to confirm that the biotic ligand model (BLM) for As(V), which was originally developed using A. fischeri, can predict As(V) toxicity to terrestrial plant species (i.e., Hordeum vulgare and T. aestivum) by optimizing the inherent sensitivity (IS)
The EC50 {HAsO4 2− } of H. vulgare significantly decreased from 45.1 ± 4.34 to

Summary

Introduction

Consideration of Cell MembraneArsenic (As) accumulates in environmental media via both natural and anthropogenic sources and can cause severe adverse effects on human health as well as ecosystems [1–5].Because the total As concentration in the environmental media cannot accurately indicate bioavailability or ecotoxicity, it is important to rationally assess the ecotoxicity of As using suitable bioassays [6]. The ecotoxicity of As varies greatly depending on environmental factors (e.g., phosphate concentration) based on which the bioassay is performed [7,8] and on the sensitivity of the species tested [9]. The environmental factors can be considered using the biotic ligand model (BLM), which is a semi-mathematical and equilibrium model that predicts site-specific toxicity of cationic metals such as Cd, Cu, Ni, Pb, and Zn [10–13]. An et al [14] recently developed a BLM for inorganic arsenate (As(V)), which is a predominant species in surface water and surface soil porewater. This BLM can effectively predict As(V) toxicity to the bioluminescence of Aliivibrio fischeri considering phosphate competition (toxicity alleviation) and As species alteration by pH. SSD can estimate the 5% hazardous concentration (HC5), which can be defined as the total dissolved concentration of the contaminant that protects 95% of the species in the ecosystem

Objectives

Methods

Results

Conclusion