Subcellular Sequestration and Impact of Heavy Metals on the Ultrastructure and Physiology of the Multicellular Freshwater Alga Desmidium swartzii.

Ancuela Andosch,Margit Höftberger,Cornelius Lütz,Ursula Lütz-Meindl

doi:10.3390/ijms160510389

Ancuela Andosch, Margit Höftberger + Show 2 more

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https://doi.org/10.3390/ijms160510389

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Abstract

Due to modern life with increasing traffic, industrial production and agricultural practices, high amounts of heavy metals enter ecosystems and pollute soil and water. As a result, metals can be accumulated in plants and particularly in algae inhabiting peat bogs of low pH and high air humidity. In the present study, we investigated the impact and intracellular targets of aluminum, copper, cadmium, chromium VI and zinc on the filamentous green alga Desmidium swartzii, which is an important biomass producer in acid peat bogs. By means of transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) it is shown that all metals examined are taken up into Desmidium readily, where they are sequestered in cell walls and/or intracellular compartments. They cause effects on cell ultrastructure to different degrees and additionally disturb photosynthetic activity and biomass production. Our study shows a clear correlation between toxicity of a metal and the ability of the algae to compartmentalize it intracellularly. Cadmium and chromium, which are not compartmentalized, exert the most toxic effects. In addition, this study shows that the filamentous alga Desmidium reacts more sensitively to aluminum and zinc when compared to its unicellular relative Micrasterias, indicating a severe threat to the ecosystem.

Highlights

Fresh water algae inhabiting acid peat bog ponds are extremely endangered by entry of metallic pollutants arising from increasing traffic, industrial production or agricultural practices
In the present study we investigated the influence of Zn, Al, Cu, Cd and Cr on biomass production, morphogenesis, ultrastructure and physiology of Desmidium
Our results show that experimental exposure to the highest tolerated metal concentrations of Al, Cu and Zn severely harm the filamentous peat bog alga Desmidium in respect to biomass production, growth and ultrastructure

Summary

Introduction

Fresh water algae inhabiting acid peat bog ponds are extremely endangered by entry of metallic pollutants arising from increasing traffic, industrial production or agricultural practices. Aerosols, which are released in areas of high humidity [1], and disposal of waste water [2] are the main sources for metal contamination of moors and wetlands. Metals such as cadmium, copper, chromium, aluminum and zinc have been shown to evoke severe damage to algal metabolism by displacing essential ions, interacting with enzymes, hampering uptake of essential nutrients or generally influencing intracellular ionic balance (see [3,4,5,6] and references ). Investigation on intracellular localization of metals at high resolution as provided by analytical TEM is required for understanding the danger of metal impact, in order to obtain insight into metal detoxification and to find solutions for amelioration of metal effects (see e.g., [12])

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