The Effects of Lead and Copper on the Cellular Architecture and Metabolism of the Red AlgaGracilaria domingensis

Abstract

The effect of lead and copper on apical segments of Gracilaria domingensis was examined. Over a period of 7 days, the segments were cultivated with concentrations of 5 and 10 ppm under laboratory conditions. The samples were processed for light, confocal, and electron microscopy, as well as histochemistry, to evaluate growth rates, mitochondrial activity, protein levels, chlorophyll a, phycobiliproteins, and carotenoids. After 7 days of exposure to lead and copper, growth rates were slower than control, and biomass loss was observed on copper-treated plants. Ultrastructural damage was primarily observed in the internal organization of chloroplasts and cell wall thickness. X-ray microanalysis detected lead in the cell wall, while copper was detected in both the cytoplasm and cell wall. Moreover, lead and copper exposure led to photodamage of photosynthetic pigments and, consequently, changes in photosynthesis. However, protein content and glutathione reductase activity decreased only in the copper treatments. In both treatments, decreased mitochondrial NADH dehydrogenase activity was observed. Taken together, the present study demonstrates that (1) heavy metals such as lead and copper negatively affect various morphological, physiological, and biochemical processes in G. domingensis and (2) copper is more toxic than lead in G. domingensis.

Influence of cadmium and salinity in the red alga Pterocladiella capillacea: cell morphology, photosynthetic performance and antioxidant systems

“…Similar results were observed by Collén et al (2003) in Gracilaria tenuistipitata C. F. Chang & B. M. Xia treated with Cd and Cu and by Gouveia et al (2013) in Gracilaria domingensis (Kützing) Sonder ex Dickie treated with Cu. They proposed that the decreased content of protein could have been caused by toxic effects to protein or amino acid synthesis, as well as nitrate reduction.…”

Growth and photosynthetic pigments of Gracilariopsis tenuifrons (Rhodophyta, Gracilariaceae) under high light in vitro culture

“…Phycobiliproteins, the characteristic reddish pigment of red macroalgae, are the most sensitive antenna pigment, localized externally to the reaction center and the first photosynthetic pigment to decrease in concentration under light stress (Bouzon et al 2012, Gouveia et al 2013. Under the most extreme condition of this experiment (day 7, 1000 μmol photons m −2 s −1 ), the apical portions of G. tenuifrons were completely yellowish (Fig.…”

Heavy Metal-Induced Oxidative Stress in Plants: Response of the Antioxidative System

“…In some cases, like in Cu and Zn-treated Scenedesmus sp. cells, Car content was unchanged during the treatments showing that some algal species use other mechanisms in protection from metal-induced oxidative stress , while in some red algae, Pb and Cu treatments significantly decreased total carotenoid content (Gouveia et al 2013).…”

“…Studies on Anabaena flos-aquae show that cellular proteins, including phycocyanin, represent the main targets of metal toxicity, which was more pronounced in the protein profile after Cu treatment under different temperature levels, compared to Cd treatment in the same temperature range (Surosz and Palinska 2005). Pb and Cu exposure significantly decreased the total phycobiliprotein content in rhodophyte Gracilaria domingensis (Gouveia et al 2013), which was also observed for several cyanobacterial species, such as in S. platensis when exposed to Pb (Arunakumara and Zhang 2007) and after Ni or Pb exposure in Oscillatoria sp. and Westiellopsis sp., particularly in longer treatments.…”