Cadmium-induced changes in trace element bioaccumulation and proteomics perspective in four marine bivalves

Abstract

Bivalves are employed widely as biomonitors of metal pollution and proteomics has increasingly been applied to solve ecotoxicological issues. This study aimed to investigate the effects of Cd exposure on the bioaccumulation of other trace elements and reveal the molecular mechanisms using proteomics technologies. The results showed that Cd exposure resulted in remarkable changes in body concentrations of Zn, Cu, Ag, Co, Ni, Pb, and Se in four marine bivalves (scallop Chlamys nobilis, clam Ruditapes philippinarum, mussel Perna viridis, and oyster Saccostrea cucullata). Generally, the bivalves exposed to higher Cd concentration accumulated higher concentrations of Zn, Cu, and Se, but a lower concentration of Co. The accumulation of Ag, Ni, and Pb was specific for different species. The data strongly suggest that the influences of one metal exposure on the bioaccumulation of other metals/metalloids need to be considered in interpreting body concentrations of the elements in the biomonitors. Cd exposure had little effect on bivalve proteomes, and the identified proteins were insufficient to explain the observed disruption of trace element metabolism. However, protein expression signatures composed of the altered proteins could distinguish the clams and the mussels with different body Cd levels. The strong up-regulation of galectin in Cd-exposed oysters indicated the protein as a novel biomarker in environmental monitoring.

Proteome pattern in oysters as a diagnostic tool for metal pollution

“…Actually, many pathology studies have shown the feasibility of disease diagnosis and prediction based solely on the molecular expression patterns, independent of biological knowledge of the molecules [37,38]. Recently, the concept of protein expression pattern/signature (PES) evolved from these human clinical proteomics has been increasingly applied in environmentally relevant organisms [15][16][17]32]. PES is defined as a set of proteins as biomarkers of specific environmental stressors.…”

“…The gill proteome was visualized by a silver staining method compatible with MS analysis, and the detailed procedures are described in our previous study [32]. The silver staining allows for detection of <1 ng protein per spot, and the method has proven effective in quantification and mass spectrometric sequencing of proteins [21,32,33].…”

“…The interesting proteins were putatively identified by homology searches following MS/MS analysis as described in the previous study [32], since the genetic information of the oyster is not available yet. Briefly, differentially expressed protein spots were digested with trypsin, and peptides were extracted with 50% acetonitrile plus 0.1% trifluoroacetic acid.…”

“…The silver staining allows for detection of <1 ng protein per spot, and the method has proven effective in quantification and mass spectrometric sequencing of proteins [21,32,33]. Briefly, the gill proteins were extracted in 10% trichloroethanoic acid/acetone (w/v) buffer, and protein concentration was determined by a 2-D Quant Kit assay (GE Healthcare).…”

Effect of cadmium on the defense response of Pacific oyster Crassostrea gigas to Listonella anguillarum challenge

“…The third group (Cd+ La -exposed group) were exposed to Cd 2+ (20 μg/L) throughout the experiment and challenged with L . anguillarum (5×10 6 CFU/mL) after 48 h. The concentration of Cd used in the experiment (20 μg/L) is similar to that at several points along the Bohai coast and has been used by many researchers to study the adverse effects of cadmium on the mollusks (Zhang, 2001;Wu and Wang, 2011;Liu et al, 2012). When appropriate, Cd 2+ and L .…”