Changes in protein expression of pacific oyster Crassostrea gigas exposed in situ to urban sewage

Abstract

The composition and concentration of substances in urban effluents are complex and difficult to measure. These contaminants elicit biological responses in the exposed organisms. Proteomic analysis is a powerful tool in environmental toxicology by evidencing alterations in protein expression due to exposure to contaminants and by providing a useful framework for the development of new potential biomarkers. The aim of this study was to determine changes in protein expression signatures (PES) in the digestive gland of oysters Crassostrea gigas transplanted to two farming areas (LIS and RIB) and to one area contaminated by sanitary sewage (BUC) after 14 days of exposure. This species is one of the most cultivated molluscs in the world. The identified proteins are related to the cytoskeleton (CKAP5 and ACT2), ubiquitination pathway conjugation (UBE3C), G protein-coupled receptor and signal transduction (SVEP1), and cell cycle/division (CCNB3). CKAP5 showed higher expression in oysters kept at BUC in comparison with those kept at the farming areas, while ACT2, UBE3C, SVEP1, and CCNB3 were suppressed. The results suggest that these changes might lead to DNA damage, apoptosis, and interference with the immune system in oyster C. gigas exposed to sewage and give initial information on PES of C. gigas exposed to sanitary sewage, which can subsequently be useful in the development of more sensitive tools for biomonitoring coastal areas, particularly those devoted mainly to oyster farming activities.

Thiol oxidation of hemolymph proteins in oysters Crassostrea brasiliana as markers of oxidative damage induced by urban sewage exposure

“…Sediments from CAM1 had the highest concentrations of total PAHs, PCBs, LABs, and steroids, whereas CAM2 had the highest concentrations of DDT. Notably, total PAHs were considerably lower (1–3 orders of magnitude) compared with contaminated areas with known petrogenic and pyrolytic inputs and similar to values found at major oyster farming areas in Brazil . Total PCBs and DDTs were also detected at relatively low concentrations compared with other contaminated areas .…”

“…Moreover, PAH, PCB, and organochlorine pesticide concentrations in sediments at both sites were below the maximum concentration recommended by MMA, the Brazilian environmental agency . Concentrations of LABs and steroids in sediments are not included in the Brazilian environmental agency regulations, but total LAB concentrations in the sediment of CAM1 were close to the values detected in industrialized areas of China and areas with pronounced input of urban sewage in Brazil , suggesting a significant sewage input in the region. Total steroid concentrations in CAM1 were also high.…”

“…The CAM1 group also presented the highest thermotolerant coliforms levels, an indication of fecal contamination in this area. These levels were an order of magnitude lower than the thermotolerant coliforms detected at the mouth of the Bücheler River, an area heavily contaminated by urban sewage in Santa Catarina State . The levels of thermotolerant coliforms detected in the present study in the REF and CAM2 groups are in the same range as the ones found in aquaculture sites at Florianópolis (Santa Catarina State), the major oyster producer in Brazil .…”

“…Samples (pool of 10 oysters per group or 250 g sediment) were freeze‐dried (Thermo Savant lyophilizer, Modulyo D) for 72 h and then crushed and homogenized with a pestle. The analyses of total PCBs, PAHs, LABs, steroids, and organochloride pesticides were carried out according to the procedures detailed elsewhere . Briefly, samples (1 g for oysters and 20 g for sediments) were Soxhlet‐extracted with a 50% mixture of residue grade n‐hexane and dichloromethane.…”

Transcriptomic responses of the endangered freshwater mussel Margaritifera margaritifera to trace metal contamination in the Dronne River, France

“…While their function is unknown in bivalve molluscs, VWAcontaining proteins are present in the hemolymph of terrestrial molluscs as part of the coagulant immune system, playing a key role in the processes of susceptibility/resistance in hostparasite interactions (Bouchut et al 2006). The expression of a SVEP1-like protein was shown to be reduced in Pacific oyster Crassostrea gigas exposed to sanitary sewage discharges (Flores-Nunes et al 2015). The overexpression of SVEP1 in our mussels in response to higher metal concentrations illustrates the complexity of the immune response amongst bivalve species.…”