Proteomics as a route to identification of toxicity targets in environmental toxicology

Quantitative analysis of the polar cod (Boreogadus saida) hepatic proteome highlights interconnected responses in cellular adaptation and defence mechanisms after dietary benzo[a]pyrene exposure

Increased industrial offshore activities in northern waters raise the question of impact of polycyclic aromatic hydrocarbons (PAHs) on key Arctic marine species. One of these is the ecologically important polar cod (Boreogadus saida), which is the primary food source for Arctic marine mammals and seabirds. In the present work, we have conducted the first comprehensive proteomics study with this species by exploring the effects of dietary PAH exposure on the hepatic proteome, using benzo[a]pyrene (BaP) as a PAH model-compound. Functional annotation and pathway analyses of the proteins affected by BaP revealed a concerted cellular response for handling and adopting to its exposure, involving numerous interconnected signalling pathways and metabolic processes. In accordance with BaP being a strong aryl hydrocarbon receptor (Ahr) agonist, a prominent activation of the canonical Ahr signalling pathway was observed, including upregulation of Ahr target proteins like cytochrome P450 enzymes and microsomal glutathione transferase. Furthermore, cellular pathways for handling oxidative stress, protein misfolding and degradation, as well as endoplasmic reticulum stress and calcium homeostasis, were also activated by BaP, possibly as a result of the formation of harmful and redox reactive BaP metabolites via phase I metabolism. Activation of proteins that participate in the acute-phase response was also observed, suggesting prevalent tissue- and cellular damage that triggers the immune system and inflammatory responses. Our results at the protein level aligns well with previous analyses on the effects of BaP on the polar cod liver transcriptome and support that exposure to BaP and structural similar PAHs can cause adverse effects on polar cod physiology. Although more data is required for demonstrating how these molecular responses propagate to higher levels of biological organisation, increased knowledge about the initial cellular and molecular mechanisms that induce toxicity is a key-step towards a mechanistically informed impact assessment of PAH pollutants in the Arctic.

Comparative proteomic analysis reveals the response mechanism of freshwater leech (Whitmania pigra) under heat-stress challenge

Temperature is an environmental parameter that remarkably affects the survival and organism health of poikilothermal animal-Whitmania pigra Whitman. Heat stress destroys the physiological homeostasis of intestine tissue. However, no studies on the intestinal mucosa response of leech exposure to heat stress have been reported so far. To identify the biomarker proteins involved in heat stress response, we performed a Tandem mass tag (TMT)-based comparative proteomic analysis on leech's intestine after exposing to 27 °C and 35 °C. The cumulative mortality in the 35 °C heat stress group increased on the third day after stress compared with the control group. Mean-while, intestinal malondialdehyde (MDA) content was significantly up-regulated whereas total antioxidant capacity (T-AOC) was significantly down-regulated. A total of 3935 proteins were identified through proteomic analysis. Heat stress resulted in 144 differential proteins; 75 were up-regulated, and 69 were down-regulated. The differential expression proteins in response to heat stress are mainly involved in calcium-binding proteins, molecular chaperones, cytoskeleton integrity, immune function and inflammation response, DNA damage and repair, ribosomal protein synthesis, stress hormones and neuro-transmitters, tumorigenesis, and apoptosis. Protein-protein network interaction analysis showed that HSP, CD8A, C3, CD63, CD81, MRPL58, MRPL15, HNRNPA1, AMBP, IGHEP1, SERPINC1, CYP3A4, ATP12A, RPS13, CaM, HSP70 binding protein, HSPA6, C4A, ANXA7, ARG1, ARG2, ATP1B, CALCA, HTR1B, and GNGT1 are the critical proteins of leeches resistance to heat stress. Our results systematically provide substantial responsive candidate proteins combating heat stress and enhance our understanding of the intrinsic response mechanisms of thermal sensitivities animal W. pigra facing heat exposure.

Accumulation, biochemical responses and changes in the redox proteome promoted by Ag and Cd in the burrowing bivalve Scrobicularia plana

Silver (Ag) and cadmium (Cd) are non-essential metals that, as a result of natural processes and human activities, reach the aquatic environment where they interact with biota inducing potential toxic effects. To determine the biological effects of these metals on the endobenthic bivalve Scrobicularia plana, specimens were exposed to Ag and Cd at two concentrations, 5 and 50 μg∙L-1, for 7 days in a controlled microcosm system. The levels of the metals were measured in the seawater, sediments and clam tissues. The possible toxic biological effects of Ag and Cd were studied using a battery of biochemical biomarkers that are responsive to oxidative stress: superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione-S-transferase (GST) activities, and metallothioneins (MTs) and lipid peroxidation (LPO) levels. Since both metals have been linked to oxidative stress, redox modifications to proteins were studied by differential isotopic labelling of the oxidised and reduced forms of cysteines (Cys). An accumulation of metals was observed in the digestive gland and gills following exposure, together with the activation of enzyme activities (SOD for the Cd exposure; SOD, CAT, GST, and GR for the Ag exposure). The MT and LPO levels (after individual exposure to Ag and Cd) increased, which suggests the existence of antioxidant and detoxification processes to mitigate the toxic oxidative effects of both metals. The redox proteomic analysis identified 771 Cys-containing peptides (out of 514 proteins), of which 195 and 226 changed after exposure to Ag and Cd, respectively. Bioinformatics analysis showed that exposure to metal affects relevant functional pathways and biological processes in S. plana, such as: "cellular respiration" (Ag), "metabolism of amino acids" and "synthesis and degradation of proteins" (Ag and Cd), "carbohydrate metabolism" and "oxidative stress" (Cd). The proteomic approach implemented here is a powerful complement to conventional biochemical biomarkers, since it evaluates changes at the protein level in a high-throughput unbiased manner, thus providing a general appraisal of the biological responses altered by exposure to the contaminants.

Microcystin-LR activates serine/threonine kinases and alters the phosphoproteome in human HepaRG cells

Microcystin-LR (MCLR) exposure has been associated with development of hepatocellular carcinoma (HCC). Many of the carcinogenic mechanisms for MCLR have been attributed to the induction of cell survival and proliferation through altered protein phosphorylation pathways by inhibition of protein phosphatases 1 (PP1) and PP2A. The current study determined MCLR effects on the phosphoproteome in human HepaRG cells. Differentiated HepaRG cells were treated with either vehicle or MCLR followed by phosphoproteomic analysis and Western blotting of MAPK-activated proteins. MCLR decreased cell viability at 24 h at doses as low as 0.03 μM. MCLR also caused a dose-dependent increase in phosphorylation of signaling and stress kinases. The number of decreased phosphosites by 0.1 μM MCLR was similar between the 2 h (212) and 24 h (154) timepoints. In contrast, a greater number of phosphosites were increased at 24 h (567) versus the 2 h timepoint (136), indicating the hyperphosphorylation state caused by MCLR-mediated inhibition of PPs is time-dependent. A kinase perturbation analysis predicted that MCLR exposure at both 2 h and 24 h increased the function of aurora kinase B (AURKB), checkpoint kinase 1 (CHEK1), and serum and glucocorticoid-regulated kinase 1 (SGK1). STRING database analysis of the phosphosites altered by MCLR exposure revealed pathways associated with cell proliferation and survival, including ribosomal protein S6 kinase (RSK), and vascular endothelial growth factor receptor (VEGFR2)-mediated vascular permeability. In addition, several cancer-related KEGG pathways were enriched at both 2 h and 24 h timepoints, and multiple cancer-related disease-gene associations were identified at the 24 h timepoint. Many of the kinases and pathways described above play crucial roles in the development of HCC by affecting processes such as invasion and metastasis. Overall, our data indicate that MCLR-mediated changes in protein phosphorylation involve biological pathways related to carcinogenesis that may contribute to the development of HCC.

Proteomic evaluation of nanotoxicity in aquatic organisms: A review

The alteration of organisms protein functions by engineered nanoparticles (ENPs) is dependent on the complex interplay between their inherent physicochemical properties (e.g., size, surface coating, shape) and environmental conditions (e.g., pH, organic matter). To date, there is increasing interest on the use of 'omics' approaches, such as proteomics, genomics, and others, to study ENPs-biomolecules interactions in aquatic organisms. However, although proteomics has recently been applied to investigate effects of ENPs and associated mechanisms in aquatic organisms, its use remain limited. Herein, proteomics techniques widely applied to investigate ENPs-protein interactions in aquatic organisms are reviewed. Data demonstrates that 2DE and mass spectrometry and/or their combination, thereof, are the most suitable techniques to elucidate ENPs-protein interactions. Furthermore, current status on ENPs and protein interactions, and possible mechanisms of nanotoxicity with emphasis on those that exert influence at protein expression levels, and key influencing factors on ENPs-proteins interactions are outlined. Most reported studies were done using synthetic media and essay protocols and had wide variability (not standardized); this may consequently limit data application in actual environmental systems. Therefore, there is a need for studies using realistic environmental concentrations of ENPs, and actual environmental matrixes (e.g., surface water) to aid better model development of ENPs-proteins interactions in aquatic systems.

Climate change, human health, and the exposome: Utilizing OMIC technologies to navigate an era of uncertainty

Climate change is an anthropogenic phenomenon that is alarming scientists and non-scientists alike. The emission of greenhouse gases is causing the temperature of the earth to rise and this increase is accompanied by a multitude of climate change-induced environmental exposures with potential health impacts. Tracking human exposure has been a major research interest of scientists worldwide. This has led to the development of exposome studies that examine internal and external individual exposures over their lifetime and correlate them to health. The monitoring of health has also benefited from significant technological advances in the field of "omics" technologies that analyze physiological changes on the nucleic acid, protein, and metabolism levels, among others. In this review, we discuss various climate change-induced environmental exposures and their potential health implications. We also highlight the potential integration of the technological advancements in the fields of exposome tracking, climate monitoring, and omics technologies shedding light on important questions that need to be answered.

Zinc oxide, titanium dioxide and C60 fullerene nanoparticles, alone and in mixture, differently affect biomarker responses and proteome in the clam Ruditapes philippinarum

Continuous release of nanoparticles (NPs) into marine coastal environments results in an increased risk of exposure to complex NP mixtures for marine organisms. However, to date, the information on the effects at molecular and biochemical levels induced by the exposure to NPs, singly and as a mixture, is still scant. The present work aimed at exploring the independent and combined effects and the mechanism(s) of action induced by 7-days exposure to 1 μg/L nZnO, 1 μg/L nTiO₂ and 1 μg/L FC₆₀ fullerene in the Manila clam Ruditapes philippinarum, using a battery of immunological and oxidative stress biomarkers in haemolymph, gills and digestive gland. In addition, proteomics analyses were performed in gills and the digestive gland, where NP bioaccumulation was also assessed. Increased bioaccumulation of single NPs and the mixture was linked with increased oxidative stress and higher damage to proteins, lipids and DNA in all tissues analysed. The proteomics approach highlighted protein modulation in terms of abundance and damage (higher redox-thiol and carbonylated groups content). In particular, the modulated proteins (16 in gills and 18 in digestive gland) were mostly related to cytoskeleton and energetic metabolism. The digestive gland was the tissue more affected. For all biomarkers measured, increased detrimental effects were observed in the mixture compared to single NP exposures.

Nephrotoxicity evaluation and proteomic analysis in kidneys of rats exposed to thioacetamide

Thioacetamide (TAA) was administered orally at 0, 10, and 30 mg/kg body weight (BW) daily to Sprague–Dawley rats aged 6–7 weeks for 28 consecutive days. Nephrotoxicity and proteomics were evaluated in the kidneys of rats exposed to TAA. The BW decreased, however, the relative kidneys weight increased. No significant histopathologic abnormalities were found in the kidneys. The numbers of monocytes and platelets were significantly increased. However, the mean corpuscular volume and hematocrit values were decreased significantly in rats exposed to 30 mg/kg BW TAA. The expression levels of Kim-1 and NGAL were increased 4 to 5-fold in the kidneys, resulting in significant nephrotoxicity. Proteomic analysis was conducted and a total of 5221 proteins spots were resolved. Of these, 3 and 21 protein spots were up- and downregulated, respectively. The validation of seven proteins was performed by Western blot analysis. The expression level of ASAP2 was significantly upregulated, whereas RGS14, MAP7Dl, IL-3Rα, Tmod1, NQO2, and MUP were reduced. Sixteen isoforms of MUP were found by the 2DE immunoblot assay and were significantly downregulated with increasing exposure to TAA. MUP isoforms were compared in the liver, kidneys, and urine of untreated rats and a total of 43 isoforms were found.

Integrative description of changes occurring on zebrafish embryos exposed to water-soluble crude oil components and its mixture with a chemical surfactant

The effects of crude oil spills are an ongoing problem for wildlife and human health in both marine and freshwater aquatic environments. Bioassays of model organisms are a convenient way to assess the potential risks of the substances involved in oil spills. Zebrafish embryos (ZFE) are a useful to reach a fast and detailed description of the toxicity of the pollutants, including both the components of the crude oil itself and substances that are commonly used for crude oil spill mitigation (e.g. surfactants). Here, we evaluated the survival rate, as well as histological, morphological, and proteomic changes in ZFE exposed to Water Accumulated Fraction (WAF) of light crude oil and in mixture with dioctyl sulfosuccinate sodium (DOSS, e.g. CEWAF: Chemically Enhanced WAF), a surfactant that is frequently used in chemical dispersant formulations. Furthermore, we compared de hydrocarbon concentration of WAF and CEWAF of the sublethal dilution. In histological, morphological, and gene expression variables, the ZFE exposed to WAF showed less changes than those exposed to CEWAF. Proteomic changes were more dramatic in ZFE exposed to WAF, with important alterations in spliceosomal and ribosomal proteins, as well as proteins related to eye and retinal photoreceptor development and heart function. We also found that the concentration of high molecular weight hydrocarbons in water was slighly higher in presence of DOSS, but the low molecular weight hydrocarbons concentration was higher in WAF. These results provide an important starting point for identifying useful crude-oil exposure biomarkers in fish species.

Changes in global protein expression in sea turtle cells exposed to common contaminants indicates new biomarkers of chemical exposure

Non-targeted protein expression at the cellular level can provide insights into mechanistic effects of contaminants in wildlife, and hence new and potentially more accurate biomarkers of exposure and effect. However, this technique has been relatively unexplored in the realm of in vitro biomarker discovery in threatened wildlife, despite the vulnerability of this group of animals to adverse sublethal effects of contaminant exposure. Here we examined the usefulness of non-targeted protein expression for biomarker discovery in green sea turtles (Chelonia mydas) by investigating differences in the response of primary cells from five different tissue types that were exposed to three contaminants known to accumulate in this species. Cells derived from C. mydas skin, liver, kidney, ovary and small intestine were exposed to 100 μg/L of either polychlorinated biphenyl 153 (PCB153), perfluorononanoic acid (PFNA) or phenanthrene for 24 h. The global protein expression was then quantitatively evaluated using sequential window acquisition of all theoretical mass spectra (SWATH-MS). Comparison of the global protein profiles revealed that, while a majority of proteins were mutually expressed in controls of all tissue types (~90%), the response to exposure in terms of protein expression strength was significantly different between tissue types. Furthermore, a comparison to known markers of chemical exposure in sea turtles from the literature indicated that in vitro response can reflect known in vivo responses. In particular, markers such as heat shock protein (HSP) 60, glutathione S-transferases (GSTs) and superoxide dismutases (SODs), cytochrome P450 and catalase were dysregulated in response to exposure. Furthermore, potential new markers of exposure were discovered such as annexin, an important protein in cell signalling processes. While this methodology proved promising further studies are required to confirm the accuracy of in vitro protein expression as a tool for biomarker discovery in wildlife.

Chironomus riparius Proteome Responses to Spinosad Exposure

The potential of proteome responses as early-warning indicators of insecticide exposure was evaluated using the non-biting midge Chironomus riparius (Meigen) as the model organism. Chironomus riparius larvae were exposed to environmentally relevant concentrations of the neurotoxic pesticide spinosad to uncover molecular events that may provide insights on the long-term individual and population level consequences. The iTRAQ labeling method was performed to quantify protein abundance changes between exposed and non-exposed organisms. Data analysis revealed a general dose-dependent decrease in the abundance of globin proteins as a result of spinosad exposure. Additionally, the downregulation of actin and a larval cuticle protein was also observed after spinosad exposure, which may be related to previously determined C. riparius life-history traits impairment and biochemical responses. Present results suggest that protein profile changes can be used as early warning biomarkers of pesticide exposure and may provide a better mechanistic interpretation of the toxic response of organisms, aiding in the assessment of the ecological effects of environmental contamination. This work also contributes to the understanding of the sublethal effects of insecticides in invertebrates and their molecular targets.

High-multiplexed monitoring of protein biomarkers in the sentinel Gammarus fossarum by targeted scout-MRM assay, a new vision for ecotoxicoproteomics

Ecotoxicoproteomics employs mass spectrometry-based approaches centered on proteins of sentinel organisms to assess for instance, chemical toxicity in fresh water. In this study, we combined proteogenomics experiments and a novel targeted proteomics approach free from retention time scheduling called Scout-MRM. This methodology will enable the measurement of simultaneously changes in the relative abundance of multiple proteins involved in key physiological processes and potentially impacted by contaminants in the freshwater sentinel Gammarus fossarum. The development and validation of the assay were performed to target 157 protein biomarkers of this non-model organism. We carefully chose and validated the transitions to monitor using conventional parameters (linearity, repeatability, LOD, LOQ). Finally, the potential of the methodology is illustrated by measuring 277-peptide-plex assay (831 transitions) in sentinel animals exposed in natura to different agricultural sites potentially exposed to pesticide contamination. Multivariate data analyses highlighted the modulation of several key proteins involved in feeding and molting. This multiplex-targeted proteomics assay paves the way for the discovery and the use of a large panel of novel protein biomarkers in emergent ecotoxicological models for environmental monitoring in the future. BIOLOGICAL SIGNIFICANCE: The study contributed to the development of Scout-MRM for the high-throughput quantitation of a large panel of proteins in the Gammarus fossarum freshwater sentinel. Increasing the number of markers in ecotoxicoproteomics is of most interest to assess the impact of pollutants in freshwater organisms. The development and validation of the assay enabled the monitoring of a large panel of reporter peptides of exposed gammarids. To illustrate the applicability of the methodology, animals from different agricultural sites were analysed. The application of the assay highlighted the modulation of some biomarker proteins involved in key physiological pathways, such as molting, feeding and general stress response. Increasing multiplexing capabilities and field test will provide the development of diagnostic protein biomarkers for emergent ecotoxicological models in future environmental biomonitoring programs.

Use of an Exposome Approach to Understand the Effects of Exposures From the Natural, Built, and Social Environments on Cardio-Vascular Disease Onset, Progression, and Outcomes

Obesity, diabetes, and hypertension have increased by epidemic proportions in recent years among African Americans in comparison to Whites resulting in significant adverse cardiovascular disease (CVD) disparities. Today, African Americans are 30% more likely to die of heart disease than Whites and twice as likely to have a stroke. The causes of these disparities are not yet well-understood. Improved methods for identifying underlying risk factors is a critical first step toward reducing Black:White CVD disparities. This article will focus on environmental exposures in the external environment and how they can lead to changes at the cellular, molecular, and organ level to increase the personal risk for CVD and lead to population level CVD racial disparities. The external environment is defined in three broad domains: natural (air, water, land), built (places you live, work, and play) and social (social, demographic, economic, and political). We will describe how environmental exposures in the natural, built, and social environments "get under the skin" to affect gene expression though epigenetic, pan-omics, and related mechanisms that lead to increased risk for adverse CVD health outcomes and population level disparities. We also will examine the important role of metabolomics, proteomics, transcriptomics, genomics, and epigenomics in understanding how exposures in the natural, built, and social environments lead to CVD disparities with implications for clinical, public health, and policy interventions. In this review, we apply an exposome approach to Black:White CVD racial disparities. The exposome is a measure of all the exposures of an individual across the life course and the relationship of those exposures to health effects. The exposome represents the totality of exogenous (external) and endogenous (internal) exposures from conception onwards, simultaneously distinguishing, characterizing, and quantifying etiologic, mediating, moderating, and co-occurring risk and protective factors and their relationship to disease. Specifically, it assesses the biological mechanisms and underlying pathways through which chemical and non-chemical environmental exposures are associated with CVD onset, progression and outcomes. The exposome is a promising approach for understanding the complex relationships among environment, behavior, biology, genetics, and disease phenotypes that underlie population level, Black: White CVD disparities.

Changes in protein expression in mussels Mytilus galloprovincialis dietarily exposed to PVP/PEI coated silver nanoparticles at different seasons

Potential toxic effects of Ag NPs ingested through the food web and depending on the season have not been addressed in marine bivalves. This work aimed to assess differences in protein expression in the digestive gland of female mussels after dietary exposure to Ag NPs in autumn and spring. Mussels were fed daily with microalgae previously exposed for 24 h to 10 μg/L of PVP/PEI coated 5 nm Ag NPs. After 21 days, mussels significantly accumulated Ag in both seasons and Ag NPs were found within digestive gland cells and gills. Two-dimensional electrophoresis distinguished 104 differentially expressed protein spots in autumn and 142 in spring. Among them, chitinase like protein-3, partial and glyceraldehyde-3-phosphate dehydrogenase, that are involved in amino sugar and nucleotide sugar metabolism, carbon metabolism, glycolysis/gluconeogenesis and the biosynthesis of amino acids KEGG pathways, were overexpressed in autumn but underexpressed in spring. In autumn, pyruvate metabolism, citrate cycle, cysteine and methionine metabolism and glyoxylate and dicarboxylate metabolism were altered, while in spring, proteins related to the formation of phagosomes and hydrogen peroxide metabolism were differentially expressed. Overall, protein expression signatures depended on season and Ag NPs exposure, suggesting that season significantly influences responses of mussels to NP exposure.

Proteomic Analysis of Zebrafish (Danio rerio) After Chemical Exposure

Traditional toxicological screens based on the zebrafish model use observable phenotypic endpoints during their development to determine the toxicity of teratogens. Yet toxicity does not always translate to obvious phenotypic changes and the criteria used to score the toxicity of a teratogen are frequently subjected to human perception. The advancement in omics-based technologies has allowed us to quantitatively and objectively determine the toxicity of a teratogen based on biomolecular changes. The field of proteomics has been gaining popularity as a valuable tool in toxicology. Hence, in this chapter, we described a protocol for both label-free and label-based proteomic methods to analyse proteomic changes in both embryos and adult livers of zebrafish exposed to the teratogen TCDD (tetrachlorodibenzo-p-dioxin) as an example.

Differences among Unique Nanoparticle Protein Corona Constructs: A Case Study Using Data Analytics and Multi-Variant Visualization to Describe Physicochemical Characteristics

Gold nanoparticles (AuNPs) used in pharmaceutical treatments have been shown to effectively deliver a payload, such as an active pharmaceutical ingredient or image contrast agent, to targeted tissues in need of therapy or diagnostics while minimizing exposure, availability, and accumulation to surrounding biological compartments. Data sets collected in this field of study include some toxico- and pharmacodynamic properties (e.g., distribution and metabolism) but many studies lack information about adsorption of biological molecules or absorption into cells. When nanoparticles are suspended in blood serum, a protein corona cloud forms around its surface. The extent of the applications and implications of this formed cloud are unknown. Some researchers have speculated that the successful use of nanoparticles in pharmaceutical treatments relies on a comprehensive understanding of the protein corona composition. The work presented in this paper uses a suite of data analytics and multi-variant visualization techniques to elucidate particle-to-protein interactions at the molecular level. Through mass spectrometry analyses, corona proteins were identified through large and complex datasets. With such high-output analyses, complex datasets pose a challenge when visualizing and communicating nanoparticle-protein interactions. Thus, the creation of a streamlined visualization method is necessary. A series of user-friendly data informatics techniques were used to demonstrate the data flow of protein corona characteristics. Multi-variant heat maps, pie charts, tables, and three-dimensional regression analyses were used to improve results interpretation, facilitate an iterative data transfer process, and emphasize features of the nanoparticle-protein corona system that might be controllable. Data informatics successfully highlights the differences between protein corona compositions and how they relate to nanoparticle surface charge.

Metabolomic alterations and oxidative stress are associated with environmental pollution in Procambarus clarkii

Soils contaminated by toxic metallic elements from agricultural activities raise grave concern about their potential risk to human health through direct intake, bioaccumulation through the food chain, and their impacts on ecological systems. We have measured here the lipid and protein oxidation status and used metabolomic methodologies to identify and characterize the changes caused by metal pollution exposure in the digestive glands and gills of Procambarus clarkii, the red swamp crayfish. Specimens captured at two sites with intensive agriculture practices using diverse types of agrochemicals, located in the borders of Doñana Natural Park, were compared to ones caught in the core of the Park, a proven non-polluted place. As a highly metabolically active organ, the digestive gland accumulated more metallic elements than the gills and was consequently more affected at the metabolic level. Results also indicate that chronic pollution exposure generates oxidative stress and mitochondrial dysfunction that imposes a metabolic shift to enhanced aerobic glycolysis and lipid metabolism alteration. The integration of metabolomics with previous proteomic data gives a comprehensive vision of the metabolic disorders caused by chronic metal exposure to P. clarkii and identifies potential biomarkers useful for routine risk assessment of the aquatic ecosystems health.

Effects of novel brominated flame retardant TBBPA on human airway epithelial cell (A549) in vitro and proteome profiling

The cellular toxicity response of human airway epithelial cells (A549) to tetrabromobisphenol (TBBPA) was assessed in vitro. Cell viability, levels of intracellular reactive oxygen species (ROS), lipid peroxidation (MDA), and caspase-3 activity were determined after A549 treated with varying concentrations of TBBPA. A comparative proteomic analysis was performed in cells treated with different concentrations of TBBPA (0, 10, and 40 μg/mL). Two-way anova analysis showed that cell viability was significantly decreased after treatment by TBBPA with a concentration of 16 μg/mL for 48 hr, however, the caspase-3 activities, ROS generation, and MDA content increased. Ultrastructural observation revealed that the cell was morphological damaged after exposure to 64 μg/mL TBBPA, with mitochondria seriously injured and the smooth endoplasmic reticulum dilated. There was a good correlation between ROS generation and mitochondrial dysfunction. Seventeen differentially expressed proteins involved in various biological processes were identified. These findings provide a basis for understanding the mechanisms of cell dysfunction and perturbation of antioxidant status induced by additive flame retardant on airway epithelial cells.

'Omic' technologies as a helpful tool in radioecological research

This article presents a brief review of the modern 'omic' technologies, namely genomics, epigenomics, transcriptomics, proteomics, and metabolomics, as well as the examples of their possible use in radioecology. For each technology, a short description of advances, limitations, and instrumental applications is given. In addition, the review contains examples of successful use of 'omic' technologies in the assessment of biological effects of pollutants in the field conditions.

Proteomic response of gill microsomes of Crassostrea brasiliana exposed to diesel fuel water-accommodated fraction

Diesel fuel water-accommodated fraction (diesel-WAF) is a complex mixture of organic compounds that may cause harmful effects to marine invertebrates. Expression of microsomal proteins can be changed by oil exposure, causing functional alterations in endoplasmic reticulum (ER). The aim of this study was to investigate changes in protein expression signatures in microsomes of oysterl Crassostrea brasiliana (=C.gasar) gill after exposure to 10% diesel-WAF for 24 and 72 h. Protein expression signatures of gills of oysters exposed to diesel-WAF were compared to those of unexposed oysters using two-dimensional electrophoresis (2-DE) to identify differentially expressed proteins. A total of 458 protein spots with molecular weights between 30-75 kDa were detected by 2-DE in six replicates of exposed oyster proteomes compared to unexposed ones. Fourteen differentially expressed proteins (six up-regulated and eight down-regulated) were identified. They are: proteins related to xenobiotic biotransformation (cytochrome P450 6 A, NADPH-cytochrome P450 reductase); cytoskeleton (α-tubulin, β-tubulin, gelsolin); processing and degradation of proteins pathways (thioredoxin domain-containing protein E3 ubiquitin-protein ligase MIB2); involved in the biosynthesis of glycolipids and glycoproteins (beta-1,3-galactosyltransferase 1); associated with stress responses (glutamate receptor 4 and 14-3-3 protein zeta, corticotropin-releasing factor-binding protein); plasmalogen biosynthesis (fatty acyl-CoA reductase 1), and sodium-and chloride-dependent glycine transporter 2 and glyoxylate reductase/hydroxypyruvate reductase. Different patterns of protein responses were observed between 24 and 72 h-exposed groups. Expression pattern of microsomal proteins provided a first insight on the potential diesel-WAF effects at protein level in microsomal fraction of oyster gills and indicated new potential biomarkers of exposure and effect. The present work can be a basis for future ecotoxicological studies in oysters aiming to elucidate the molecular mechanisms behind diesel-WAF toxicity and for environmental monitoring programs.

Role of endocytotic uptake routes in impacting the ROS-related toxicity of silver nanoparticles to Mytilus galloprovincialis: A redox proteomic investigation

Oxidative stress is often implicated in nanoparticle toxicity. Several studies have highlighted the role of internalization routes in determining nanotoxicity. Here, we investigate how two endocytotic mechanisms (clathrin- and caveolae-mediated) impact on redox balance in gill and digestive gland of the mussel, Mytilus galloprovincialis. Animals were exposed (for 3, 6 and 12 h) to two sizes of silver nanoparticles (AgNP: <50 nm and <100 nm) prior to and after blockade of two endocytic pathways (amantadine blocks clathrin-mediated endocytosis while nystatin blocks caveolae-mediated endocytosis). Redox-proteomic tools were used to determine effects. Our results demonstrate the ability of both sizes of AgNP (<50 and <100 nm) to cause protein thiol oxidation and/or protein carbonylation. However, blockade of endocytotic routes mitigated AgNP toxicity. Differential ROS-related toxicity of AgNP to mussel tissues seemed to be linked to tissue-specific mode of action requirements. Cell uptake mechanism strongly influences toxicity of AgNPs in this filter-feeder.

A proteomic study of the pulmonary injury induced by microcystin-LR in mice

MCLR has been shown to act as potent hepatotoxin, and recent studies showed that MCs can accumulate in lung tissue and exert adverse effects. However, the exact mechanism still remain unclear. The present study mainly focuses on the impairments of respiratory system after MCLR exposure in mice. After intratracheal instillation with MCLR (0, 10 and 25 μg/kg bw), histological change was examined in MCLR exposure groups. Results indicated that exposure of MCLR led to serious histopathology alteration and apoptosis in lung of mice. To further our understanding of the toxic effects of MCLR on the lung, we employed a proteomic method to search the mechanisms behind MCLR-induced pulmonary injury. In total, 38 proteins were identified to be significantly altered after MCLR exposure. These proteins involved in inflammatory response, apoptosis, cytoskeleton, and energetic metabolism, suggesting MCLR exerts complex toxic effects contributing to pulmonary injury. Furthermore, MCLR also induced pulmonary inflammation, as manifested by up-regulating the protein levels of interleukin-1β (IL-1β) and p65 subunit. Our results indicated that MCLR exerts lung injury mainly by generating inflammation and apoptosis.

An investigation of methyl tert‑butyl ether‑induced cytotoxicity and protein profile in Chinese hamster ovary cells

Methyl tert-butyl ether (MTBE) is widely used as an oxygenating agent in gasoline to reduce harmful emissions. However, previous studies have demonstrated that MTBE is a cytotoxic substance that has harmful effects in vivo and in vitro. Although remarkable progress has been made in elucidating the mechanisms underlying the MTBE-induced reproductive toxicological effect in different cell lines, the precise mechanisms remain far from understood. The present study aimed to evaluate whether mammalian ovary cells were sensitive to MTBE exposure in vitro by assessing cell viability, lactate dehydrogenase (LDH) leakage, malondialdehyde (MDA) content and antioxidant enzyme activities. In addition, the effect of MTBE exposure on differential protein expression profiles was examined by two-dimensional electrophoresis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry. MTBE exposure induced significant effects on cell viability, LDH leakage, plasma membrane damage and the activity of antioxidant enzymes. In the proteomic analysis, 24 proteins were demonstrated to be significantly affected by MTBE exposure. Functional analysis indicated that these proteins were involved in catalytic activity, binding, structural molecule activity, metabolic processes, cellular processes and localization, highlighting the fact that the cytotoxic mechanisms resulting from MTBE exposure are complex and diverse. The altered expression levels of two representative proteins, heat shock protein family A (Hsp70) members 8 and 9, were further confirmed by western blot analysis. The results revealed that MTBE exposure affects protein expression in Chinese hamster ovary cells and that oxidative stress and altered protein levels constitute the mechanisms underlying MTBE-induced cytotoxicity. These findings provided novel insights into the biochemical mechanisms involved in MTBE-induced cytotoxicity in the reproductive system.

Study of the plasma proteome of Atlantic cod (Gadus morhua): Effect of exposure to two PAHs and their corresponding diols

Occurrence of polycyclic aromatic hydrocarbon (PAH) contamination in the marine environment represents a risk to marine life and humans. In this study, plasma samples from Atlantic cod (Gadus morhua) were analysed by shotgun mass spectrometry to investigate the plasma proteome in response to exposure to single PAHs (naphthalene or chrysene) and their corresponding metabolites (dihydrodiols). In total, 369 proteins were identified and ranked according to their relative abundance. The levels of 12 proteins were found significantly altered in PAH exposed fish and are proposed as new biomarker candidates. Eleven proteins were upregulated, primarily immunoglobulin components, and one protein was downregulated (antifreeze protein type IV.) The uniformity of the upregulated proteins suggests a triggered immune response in the exposed fish. Overall, the results provide valuable knowledge for future studies of the Atlantic cod plasma proteome and generate grounds for establishing new plasma protein biomarkers for environmental monitoring of PAH related exposure.

Plant chromium uptake and transport, physiological effects and recent advances in molecular investigations

Increasingly, anthropogenic perturbations of the biosphere manifest in a broad array of global phenomena, causing widespread contamination of most ecosystems, with high dispersion rates of many contaminants throughout different environmental compartments, including metals. Chromium (Cr) contamination in particular, is, increasingly, posing a serious threat to the environment, emerging as a major health hazard to the biota. However, although the molecular and physiological mechanisms of plant responses to many heavy metals, especially lead (Pb) and cadmium (Cd), have been focused upon in recent years, chromium has attracted significantly less attention. In this context, this review discusses aspects of Cr uptake and transport, some physiological and biochemical effects of Cr exposure in plants, and molecular defense mechanisms against this metal. Recent advances in determining these responses, in fields of knowledge such as genomics, proteomics and metallomics, are discussed herein.

Cylindrospermopsin effects on protein profile of HepG2 cells

Human hepatoma cells (HepG2) were exposed to purified cylindrospermopsin (CYN), a potent toxicant for eukaryotic cells produced by several cyanobacteria. Exposure to 10 μg l^-1 of CYN for 24 h resulted in alteration of expression of 48 proteins, from which 26 were identified through mass spectrometry. Exposure to 100 μg l^-1 of CYN for 24 h affected nuclear area and actin filaments intensity, which can be associated with cell proliferation and toxicity. The proteins are implicated in different biological processes: protein folding, xenobiotic efflux, antioxidant defense, energy metabolism and cell anabolism, cell signaling, tumorigenic potential, and cytoskeleton structure. Protein profile indicates that CYN exposure may lead to alteration of glucose metabolism that can be associated with the supply of useful energy to cells respond to chemical stress and proliferate. Increase of G protein-coupled receptors (GPCRs), heterogeneous nuclear ribonucleoproteins (hnRNP), and reactive oxygen species (ROS) levels observed in HepG2 cells can associate with cell proliferation and resistance. Increase of MRP3 and glutathione peroxidase can protect cells against some chemicals and ROS. CYN exposure also led to alteration of the expression of cytoskeleton proteins, which may be associated with cell proliferation and toxicity.

Early alterations on photosynthesis-related parameters in Chlamydomonas reinhardtii cells exposed to atrazine: A multiple approach study

Chlamydomonas reinhardtii cells were exposed to a sublethal concentration of the widespread herbicide atrazine for 3h. Physiological cellular parameters, such as chlorophyll a fluorescence and oxidative stress monitored by flow cytometry and pigments levels were altered in microalgal cells exposed to 0.25 μM of atrazine. Furthermore, the effects of this herbicide on C. reinhardtii were explored using "omics" techniques. Transcriptomic analyses, carried out by RNA-Seq technique, displayed 9 differentially expressed genes, related to photosynthesis, between control cultures and atrazine exposed cultures. Proteomic profiles were obtained using iTRAQ tags and MALDI-MS/MS analysis, identifying important changes in the proteome during atrazine stress; 5 proteins related to photosynthesis were downexpressed. The results of these experiments advance the understanding of photosynthetic adjustments that occur during an early herbicide exposure. Inhibition of photosynthesis induced by atrazine toxicity will affect the entire physiological and biochemical states of microalgal cells.

Proteomic and Real-Time PCR analyses of Saccharomyces cerevisiae VL3 exposed to microcystin-LR reveals a set of protein alterations transversal to several eukaryotic models

Some of the most common toxins present in freshwater, in particular microcystins (MCs), are produced by cyanobacteria. These toxins have a negative impact on human health, being associated with episodes of acute hepatotoxicity and being considered potentially carcinogenic to humans. To date the exact mechanisms of MC-induced toxicity and tumor promotion were not completely elucidated. To get new insights underlying microcystin-LR (MCLR) molecular mechanisms of toxicity we have performed the proteomic profiling using two-dimensional electrophoresis and MALDI-TOF/TOF of Saccharomyces cerevisiae cells exposed for 4 h-1 nM and 1 μM of MCLR, and compared them to the control (cells not exposed to MCLR). We identified 14 differentially expressed proteins. The identified proteins are involved in metabolism, genotoxicity, cytotoxicity and stress response. Furthermore, we evaluated the relative expression of yeast's PP1 and PP2A genes and also of genes from the Base Excision Repair (BER) DNA-repair system, and observed that three out of the five genes analyzed displayed dose-dependent responses. Overall, the different proteins and genes affected are related to oxidative stress and apoptosis, thus reinforcing that it is probably the main mechanism of MCLR toxicity transversal to several organisms, especially at lower doses. Notwithstanding these MCLR responsive proteins could be object of further studies to evaluate their suitability as biomarkers of exposure to the toxin.

Saccharomyces cerevisiae as a model in ecotoxicological studies: A post-genomics perspective

The budding yeast Saccharomyces cerevisiae represents a well-consolidated and widely used eukaryotic model, with a number of features that make it an ideal organism to carry out functional toxicological studies. Several advantages are permitted by the use of yeast cells, as the possibility to identify molecular biomarkers, unknown mechanisms of action and novel potential targets. Thanks to the evolutionary conservation, yeast can provide also useful clues allowing the prioritization of more complex analyses and toxicity predictions in higher eukaryotes. The last two decades were incredibly fruitful for yeast "omics", but referring to the analysis of the effects of pesticides on yeast much still remains to be done. Furthermore, a deeper knowledge of the effects of environmental pollutants on biotechnological processes associated with the use of yeasts is to be hoped.

Investigation on the proteome response of transplanted blue mussel (Mytilus sp.) during a long term exposure experiment at differently impacted field stations in the German Bight (North Sea)

In a pilot field study the proteome response of Mytilus sp. was analyzed in relation to the concentration of different trace metal contaminants. Over a period of eight month test organisms have been exposed at a near-shore station in the anthropogenic impacted estuary of the river Elbe and at an off-shore station in the vicinity of the Island of Helgoland in the German Bight (North Sea). The stations differ in their hydrological as well as chemical characteristics. The physiological biomarkers, such as condition index which have been continuously monitored during the experiment clearly indicate the effects of the different environmental conditions. Multiple protein abundance changes were detected utilizing the techniques of two dimensional gel electrophoresis (2dGE) and consequently proteins arising as potential candidates for ecotoxicological monitoring have been identified by MALDI-ToF and ToF/ToF mass spectrometry. Different cytoskeletal proteins, enzymes of energy metabolism, stress proteins and one protein relevant for metal detoxification have been pointed out.

Earthworms as agents for ecotoxicity in roxarsone-contaminated soil ecosystem: a modeling study of ultrastructure and proteomics

Contamination of roxarsone has been recognized as a potential environmental hazard. In this study, Eisenia fetida samples were collected after roxarsone exposures to analyze their intestinal epithelium ultrastructure, expression levels of stress-related genes, and proteomics. Our results showed that mitochondria and endoplasmic reticulum in roxarsone-treated earthworms demonstrated variety of damages. Furthermore, 149 proteins were displayed in 2-DE, and 36 of them were identified by MALDI-TOF/TOF-MS. Those identified proteins are involved in several important processes including cell immunity, cell stress responses, and cell genetic behaviors. Our study demonstrates the toxicity responses of earthworms toward arsenic-based animal drug roxarsone with practical usefulness and demonstrates a proteomic profile change that may be critical for the roxarsone stress survival mechanisms of E. fetida. Graphical Abstract Inspiration of this referred to the form of Fig. 4 in the article "Proteomic analysis of a high aluminum tolerant yeast Rhodotorula taiwanensis RS1 in response to aluminum stress" of Chao, W et al.

The role of calcineurin signaling in microcystin-LR triggered neuronal toxicity

Microcystin-LR (MCLR) is a commonly acting potent hepatotoxin and has been pointed out of potentially causing neurotoxicity, but the exact mechanisms of action still remain unclear. Using proteomic analysis, forty-five proteins were identified to be significantly altered in hippocampal neurons of rats treated with MCLR. Among them, Ca(2+)-activated phosphatase calcineurin (CaN) and the nuclear factor of activated T-cells isoform c3 (NFATc3) were up-regulated remarkably. Validation of the changes in CaN and NFATc3 expression by Western blotting demonstrated CaN cleavage and subsequent NFATc3 nuclear translocation were generated, suggesting that exposure to MCLR leads to activation of CaN, which in turn activates NFATc3. Activation of CaN signaling has been reported to result in apoptosis via dephosphorylation of the proapoptotic Bcl-2 family member Bad. In agreement with this, our results revealed that treatment of neurons with the CaN inhibitor FK506 blocked the reduction in Bad dephosphorylation and cytochrome c (cyt c) release triggered by MCLR. Consistent with these biochemical results, we observed a marked decrease in apoptotic and necrotic cell death after MCLR exposure in the presence of FK506, supporting the hypothesis that MCLR appeared to cause neuronal toxicity by activation of CaN and the CaN-mediated mitochondrial apoptotic pathway.

Stressor-induced proteome alterations in zebrafish: a meta-analysis of response patterns

Proteomics approaches are being increasingly applied in ecotoxicology on the premise that the identification of specific protein expression changes in response to a particular chemical would allow elucidation of the underlying molecular pathways leading to an adverse effect. This in turn is expected to promote the development of focused testing strategies for specific groups of toxicants. Although both gel-based and gel-free global characterization techniques provide limited proteome coverage, the conclusions regarding the cellular processes affected are still being drawn based on the few changes detected. To investigate how specific the detected responses are, we analyzed a set of studies that characterized proteome alterations induced by various physiological, chemical and biological stressors in zebrafish, a popular model organism. Our analysis highlights several proteins and protein groups, including heat shock and oxidative stress defense proteins, energy metabolism enzymes and cytoskeletal proteins, to be most frequently identified as responding to diverse stressors. In contrast, other potentially more specifically responding protein groups are detected much less frequently. Thus, zebrafish proteome responses to stress reported by different studies appear to depend mostly on the level of stress rather than on the specific stressor itself. This suggests that the most broadly used current proteomics technologies do not provide sufficient proteome coverage to allow in-depth investigation of specific mechanisms of toxicant action. We suggest that the results of any differential proteomics experiment performed with zebrafish should be interpreted keeping in mind the list of the most frequent responders that we have identified. Similar reservations should apply to any other species where proteome responses are analyzed by global proteomics methods. Careful consideration of the reliability and significance of observed changes is necessary in order not to over-interpret the experimental results and to prevent the proliferation of false positive linkages between the chemical and the cellular functions it perturbs. We further discuss the implications of the identified "top lists" of frequently responding proteins and protein families, and suggest further directions for proteomics research in ecotoxicology. Apart from improving the proteome coverage, further research should focus on defining the significance of the observed stress response patterns for organism phenotypes and on searching for common upstream regulators that can be targeted by specific assays.

Next-generation proteomics: toward customized biomarkers for environmental biomonitoring

Because of their ecological representativeness, invertebrates are commonly employed as test organisms in ecotoxicological assessment; however, to date, biomarkers employed for these species were the result of a direct transposition from vertebrates, despite deep evolutionary divergence. To gain efficiency in the diagnostics of ecosystem health, specific biomarkers must be developed. In this sense, next-generation proteomics enables the specific identification of proteins involved in key physiological functions or defense mechanisms, which are responsive to ecotoxicological challenges. However, the analytical investment required restricts use in biomarker discovery. Routine biomarker validation and assays rely on more conventional mass spectrometers. Here, we describe how proteomics remains a challenge for ecotoxicological test organisms because of the lack of appropriate protein sequences databases, thus restricting the analysis on conserved and ubiquitous proteins. These limits and some strategies used to overcome them are discussed. These new tools, such as proteogenomics and targeted proteomics, should result in new biomarkers specific to relevant environmental organisms and applicable to routine ecotoxicological assessment.

Proteomic analysis of eucalyptus leaves unveils putative mechanisms involved in the plant response to a real condition of soil contamination by multiple heavy metals in the presence or absence of mycorrhizal/rhizobacterial additives

Here we report on the growth, accumulation performances of, and leaf proteomic changes in Eucalyptus camaldulensis plants harvested for different periods of time in an industrial, heavy metals (HMs)-contaminated site in the presence or absence of soil microorganism (AMs/PGPRs) additives. Data were compared to those of control counterparts grown in a neighboring nonpolluted district. Plants harvested in the contaminated areas grew well and accumulated HMs in their leaves. The addition of AMs/PGPRs to the polluted soil determined plant growth and metal accumulation performances that surpassed those observed in the control. Comparative proteomics suggested molecular mechanisms underlying plant adaptation to the HMs challenge. Similarly to what was observed in laboratory-scale investigations on other metal hyperaccumulators but not on HMs-sensitive plants, eucalyptus grown in the contaminated areas showed an over-representation of enzymes involved in photosynthesis and the Calvin cycle. AMs/PGPRs addition to the soil increased the activation of these energetic pathways, suggesting the existence of signaling mechanisms that address the energy/reductive power requirement associated with augmented growth performances. HMs-exposed plants presented an over-representation of antioxidant enzymes, chaperones, and proteins involved in glutathione metabolism. While some antioxidant enzymes/chaperones returned to almost normal expression values in the presence of AMs/PGPRs or in plants exposed to HMs for prolonged periods, proteins guaranteeing elevated glutathione levels were constantly over-represented. These data suggest that glutathione (and related phytochelatins) could act as key molecules for ensuring the effective formation of HMs-chelating complexes that are possibly responsible for the observed plant tolerance to metal stresses. Overall, these results suggest potential genetic traits for further selection of phytoremediating plants based on dedicated cloning or breeding programs.

Redox proteomics as biomarker for assessing the biological effects of contaminants in crayfish from Doñana National Park

Despite its environmental relevance and sensitivity, Doñana National Park (DNP) is under high ecological pressure. In crayfish (Procambarus clarkii), the utility of redox proteomics as a novel biomarker was evaluated in the aquatic ecosystems of DNP and its surroundings, where agricultural activity is a serious concern. After fluorescence labeling of reversibly oxidized Cys and 2-DE separation, the total density of proteins with reversibly oxidized thiols was found to be much higher in animals from the Matochal (MAT) and Rocina (ROC) streams, while no difference was found in crayfish from Partido (PAR) stream compared to those from the DNP core at Lucio del Palacio (the negative control). The 2-DE analysis revealed 35 spots with significant differences in thiol oxidation, among which 19 proteins were identified via MALDI-TOF/TOF. While 3 spots, identified as ferritin, showed higher oxidation levels in ROC, other identified proteins were more intense at MAT than at ROC (superoxide dismutase, protein disulfide isomerase and actin) or were overoxidized only in MAT (nucleoside diphosphate kinase, fructose-biphosphate aldolase, fatty acid-binding protein, phosphopyruvate hydratase). For most of the identified proteins, spots corresponding to different Cys oxidized forms were detected, and the native forms, without oxidized thiol groups were also found in some of them. Evidence of reversible oxidation was found for specific Cys residues, including Cys13 in ferritin as well as Cys76 and Cys108 in nucleoside diphosphate kinase. The identified thiol-oxidized proteins provide information about the metabolic pathways and/or physiological processes affected by pollutant-elicited oxidative stress.

Comparative proteomic analysis of ovary for Chinese rare minnow (Gobiocypris rarus) exposed to chlorophenol chemicals

Pentachlorophenol (PCP) and 2,4,6-trichlorophenol (TCP) are suspected of disrupting the endocrine system and thus affecting human and wildlife reproduction, but the potential common mechanisms and biomarkers of chlorophenols (CPs) in the ovary are not fully elucidated. In the present study, the female rare minnow (Gobiocypris rarus) was exposed to PCP (0.5, 5.0, and 50 μg/L), TCP (1.0, 10, and 100 μg/L) and 17β-estradiol (as a positive control) for 28 days, and the matrix-assisted laser desorption/ionization (MALDI) tandem time-of-flight (TOF/TOF) mass spectrometry analysis was employed to investigate the alteration of protein expression in the ovary. After comparison of the protein profiles from treated and control groups, 22 protein spots were observed to be altered in abundance (>2-fold) from female treated groups, and 14 protein spots were identified successfully. These proteins were related to molecular response patterns, endocrine effects, metabolic pathways, and even the possible carcinogens in response to CP exposure. The seven differentially expressed mRNA encoding proteins were measured by quantitative real-time PCR (QRT-PCR) and histopathology was also measured. Our data demonstrate that alterations of multiple pathways may be associated with the toxic effects of CPs on ovaries.

BIOLOGICAL SIGNIFICANCE

Although numerous studies have shown the affection of the endocrine system with exposure to chlorophenols (CPs), there is little report on the alterations of protein expression in the ovaries from rare minnows following exposure to PCP or TCP. In the present study, a comparative proteomic approach using two dimensional gel electrophoresis and mass spectrometry (MALDI-TOF/TOF MS) has been developed to identify certain proteins in the ovaries of Chinese rare minnow, whose abundance changes during exposure to CPs. After comparison of the protein profiles from treated and control groups, 22 protein spots were observed to be altered in abundance (>2-fold) from female treated groups, and 14 protein spots were identified successfully. These proteins were related to molecular response patterns, endocrine effects, metabolic pathways, and even the possible carcinogens in response to CP exposure. Because the mechanism often involves changes in the expression of multiple proteins rather than a single protein, a global analysis of the protein alterations can result in valuable information to understand the CP action mechanism. All the above results demonstrate that the Vtg, SUMO, Lec-3 and PIMT protein are potential biomarkers and involved in the toxicity pathway of CP exposure in aquatic animals, which should be the primary focus of studies on the CP ovary toxicity mechanism in the future.

Behavior of the edible seaweed Sargassum fusiforme to copper pollution: short-term acclimation and long-term adaptation

Aquatic agriculture in heavy-metal-polluted coastal areas faces major problems due to heavy metal transfer into aquatic organisms, leading to various unexpected changes in nutrition and primary and/or secondary metabolism. In the present study, the dual role of heavy metal copper (Cu) played in the metabolism of photosynthetic organism, the edible seaweed Sargassum fusiforme, was evaluated by characterization of biochemical and metabolic responses using both 1H NMR and GC-MS techniques under acute (47 µM, 1 day) and chronic stress (8 µM, 7 days). Consequently, photosynthesis may be seriously inhibited by acute Cu exposure, resulting in decreasing levels of carbohydrates, e.g., mannitol, the main products of photosynthesis. Ascorbate may play important roles in the antioxidant system, whose content was much more seriously decreased under acute than that under chronic Cu stress. Overall, these results showed differential toxicological responses on metabolite profiles of S. fusiforme subjected to acute and chronic Cu exposures that allowed assessment of impact of Cu on marine organisms.

Alzheimer's and Parkinson's diseases: an environmental proteomic point of view

Alzheimer's and Parkinson's diseases are severe neurodegenerative conditions triggered by complex biochemical routes. Many groups are currently pursuing the search for valuable biomarkers to either perform early diagnostic or to follow the disease's progress. Several studies have reported relevant findings regarding environmental issues and the progression of such diseases. Here the etiology and mechanisms of these diseases are briefly reviewed. Approaches that might reveal candidate biomarkers and environmental stressors associated to the diseases were analyzed under a proteomic perspective. This article is part of a Special Issue entitled: Environmental and structural proteomics.

Analysis of the Dreissena polymorpha gill proteome following exposure to dioxin-like PCBs: mechanism of action and the role of gender

PCBs are a persistent environmental problem due to their high stability and lipophilicity. The non-ortho- and the mono-ortho-substituted PCBs (dioxin-like-PCBs) share a common and well-described toxicity mechanism in vertebrates, initially involving binding to cytosolic AhRs. Invertebrate AhRs, however, show a lack of dioxin binding, and little information is available regarding the mechanism of toxicity of dl-PCBs in invertebrates. In this study, a proteomic approach was applied to analyse the variations in the pattern of the gill proteome of the freshwater mussel Dreissena polymorpha. Mussels were exposed to a mixture of dl-PCBs, and to perform a more in-depth evaluation, we chose to investigate the role of gender in the proteome response by analysing male and female mussels separately. The results revealed significant modulation of the gill tissue proteome: glycolysis and Ca(2+) homeostasis appear to be the main pathways targeted by dl-PCBs. In light of the differences between the male and female gill proteome profiles following exposure to dl-PCBs, further in-depth investigations of the role of gender in the protein expression profiles of a selected biological model are required.

Single-bilayer graphene oxide sheet impacts and underlying potential mechanism assessment in germinating faba bean (Vicia faba L.)

This study investigates the impact of different single-bilayer graphene oxide sheet (hereafter 'graphene oxide', GO; size: 0.5-5 μm) concentrations (0, 100, 200, 400, 800 and 1,600 mg L(-1)) and underlying potential mechanisms in germinating faba bean (Vicia faba L.) seedlings. The study revealed both positive and negative concentration-dependent GO-effects on V. faba. Significant negative impacts of GO concentrations (ordered by magnitude of effect: 1600>200>100 mg GO L(-1)) were indicated by decreases in growth parameters and the activity of H2O2-decomposing enzymes (ascorbate peroxidase, APX; catalase, CAT), and by increases in the levels of electrolyte leakage (EL), H2O2, and lipid and protein oxidation. The positive impacts of 400 and 800 mg GO L(-1) included significant improvements in V. faba health status indicated by decreased levels of EL, H2O2, and lipid and protein oxidation, and by enhanced H2O2-decomposing APX and CAT activity, and increased proline and seed-relative water content. V. faba seedlings-polypeptide patterns strongly substantiated these GO-concentration effects. Overall, the positive effects of these two GO concentrations (800>400 mg L(-1)) on V. faba seedlings indicate their safe nature and allow to suggest further studies.

Proteomic Analysis of the Reproductive Organs of the Hermaphroditic Gastropod Lymnaea stagnalis Exposed to Different Endocrine Disrupting Chemicals

Many studies have reported perturbations of mollusc reproduction following exposure to low concentrations (ng/L range) of endocrine disrupting chemicals (EDCs). However, the mechanisms of action of these molecules on molluscs are still poorly understood. Investigation of the modifications of protein expression in organisms exposed to chemicals using proteomic methods can provide a broader and more comprehensive understanding of adverse impacts of pollution on organisms than conventional biochemical biomarkers (e.g., heat-shock proteins, metallothioneins, GST, EROD). In this study we have investigated the impacts of four chemicals, which exhibit different endocrine disrupting properties in vertebrates, on the proteome of the hermaphroditic freshwater pulmonate gastropod Lymnaea stagnalis after 21 days of exposure. Testosterone, tributyltin, chlordecone and cyproterone acetate were chosen as tested compounds as they can induce adverse effects on the reproduction of this snail. The 2D-DIGE method was used to identify proteins whose expression was affected by these compounds. In addition to modifying the expression of proteins involved in the structure and function of the cytoskeleton, chemicals had impacts on the expression of proteins involved in the reproduction of L. stagnalis. Exposure to 19.2 µg/L of chlordecone increased the abundance of ovipostatin, a peptide transmitted during mating through seminal fluid, which reduces oviposition in this species. The expression of yolk ferritin, the vitellogenin equivalent in L. stagnalis, was reduced after exposure to 94.2 ng Sn/L of tributyltin. The identification of yolk ferritin and the modification of its expression in snails exposed to chemicals were refined using western blot analysis. Our results showed that the tested compounds influenced the abundance of yolk ferritin in the reproductive organs. Alteration in proteins involved in reproductive pathways (e.g., ovipostatin and yolk ferritin) could constitute relevant evidence of interaction of EDCs with reproductive pathways that are under the control of the endocrine system of L. stagnalis.

Impact of benzo(a)pyrene, Cu and their mixture on the proteomic response of Mytilus galloprovincialis

In natural waters, chemical interactions between mixtures of contaminants can result in potential synergistic and/or antagonic effects in aquatic animals. Benzo(a)pyrene (BaP) and copper (Cu) are two widespread environmental contaminants with known toxicity towards mussels Mytilus spp. The effects of the individual and the interaction of BaP and Cu exposures were assessed in mussels Mytilus galloprovincialis using proteomic analysis. Mussels were exposed to BaP [10 μg L(-1) (0.396 μM)], and Cu [10 μg L(-1) (0.16 μM)], as well as to their binary mixture (mixture) for a period of 7 days. Proteomic analysis showed different protein expression profiles associated to each selected contaminant condition. A non-additive combined effect was observed in mixture in terms of new and suppressed proteins. Proteins more drastically altered (new, suppressed and 2-fold differentially expressed) were excised and analyzed by mass spectrometry, and eighteen putatively identified. Protein identification demonstrated the different accumulation, metabolism and chemical interactions of BaP, Cu and their mixture, resulting in different modes of action. Proteins associated with adhesion and motility (catchin, twitchin and twitchin-like protein), cytoskeleton and cell structure (α-tubulin and actin), stress response (heat shock cognate 71, heat shock protein 70, putative C1q domain containing protein), transcription regulation (zinc-finger BED domain-containing and nuclear receptor subfamily 1G) and energy metabolism (ATP synthase F0 subunit 6 protein and mannose-6-phosphate isomerase) were assigned to all three conditions. Cu exposure alone altered proteins associated with oxidative stress (glutathione-S-transferase) and digestion, growth and remodelling processes (chitin synthase), while the mixture affected only one protein (major vault protein) possibly related to multi drug resistance. Overall, new candidate biomarkers, namely zinc-finger BED domain-containing protein, chitin synthase and major vault protein, were also identified for BaP, Cu and mixture, respectively.

Evaluation of phenanthrene toxicity on earthworm (Eisenia fetida): an ecotoxicoproteomics approach

The goal of this study was to identify promising new biomarkers of phenanthrene by identifying differentially expressed proteins in Eisenia fetida after exposure to phenanthrene. Extracts of earthworm epithelium collected at days 2, 7, 14, and 28 after phenanthrene exposure were analyzed by two dimensional electrophoresis (2-DE) and quantitative image analysis. Comparing the intensity of protein spots, 36 upregulated proteins and 45 downregulated proteins were found. Some of the downregulated and upregulated proteins were verified by MALDI-TOF/TOF-MS and database searching. Downregulated proteins in response to phenanthrene exposure were involved in glycolysis, energy metabolism, chaperones, proteolysis, protein folding and electron transport. In contrast, oxidation reduction, oxygen transport, defense systems response to pollutant, protein biosynthesis and fatty acid biosynthesis were upregulated in phenanthrene-treated E. fetida. In addition, ATP synthase b subunit, lysenin-related protein 2, lombricine kinase, glyceraldehyde 3-phosphate dehydrogenase, actinbinding protein, and extracellular globin-4 seem to be potential biomarkers since these biomarker were able to low levels (2.5 mg kg(-1)) of phenanthrene. Our study provides a functional profile of the phenanthrene-responsive proteins in earthworms. The variable levels and trends in these spots could play a potential role as novel biomarkers for monitoring the levels of phenanthrene contamination in soil ecosystems.