Omics Studies On The Toxicological Effects Of Cadmium And Arsenic In Different Developmental Stages Of The Mussel Mytilus Galloprovincialis

In recent years,the Bohai Sea has been heavily polluted by heavy metals.In this study,we selected two typical heavy metal pollutants,cadmium(Cd)and arsenic(As),for further exposure experiments.Three developmental stages of marine environmental bioindicator,mussel Mytilus galloprovincialis,were chosen for this study.We combined traditional toxicological methods and-omic technologies to investigate the toxicological effects and mechanism of heavy metal pollutants in mussels and characterized the metabolite and protein biomarkers related to the toxicological effects of Cd and As.These biomarkers may be used for marine environmental monitoring.Results are described as follows: 1.Toxicological effects of different concentrations of Cd and As(V)in D-shape larval musselsD-shape larval mussels were exposed to different concentrations of Cd(5 and 50 μg/L)and As(V)(5 and 50 μg/L)for 48 hours.Results indicated that there was no obvious aberration effect in D-shape larval mussels exposed to different concentrations of Cd and As(V).NMR-based metabolomics revealed differential metabolic responses in D-shape larval mussels exposed to Cd and As(V).Basically,both Cd and As(V)caused energy disruption,lipid metabolism and osmotic stress in D-shape larval mussels.In addition,Cd caused a dose-dependent effect in D-shape larval mussels.Proteomic analysis based on 2D electrophoresis and mass spectrometry indicated that both 5 and 50 μg/L of Cd induced cytoskeleton disruption,disturbances in energy metabolism,immune regulation and gene expression in D-shape larval mussels.The low concentration(5 μg/L)of Cd exposure caused disturbances in apoptosis,protein folding and oxidative stress in D-shape larval mussels.The high concentration(50 μg/L)of Cd exposure caused detoxication and protein metabolism in D-shape larval mussels.The low concentration(5 μg/L)of As(V)induced disturbances in protein metabolism,while the high concentration(50 μg/L)of As(V)induced immune stress and detoxication in D-shape larval mussels.2.Toxicological effects of Cd and As(V)in juvenile musselsAfter exposed to Cd(50 μg/L)and As(V)(50 μg/L)for 48 hours,juvenile mussels exhibited significant(p < 0.01)Cd accumulations in the whole soft tissues.NMR-based metabolomics revealed differential metabolic responses in juvenile mussels exposed to Cd and As(V).Both Cd and As(V)caused energy disruption and osmotic stress in juvenile mussels.Cd caused disruption of lipid metabolism in juvenile mussels.The decreased branched chain amino acids(BCAAs)suggested the immune stress caused by As(V)exposure in juvenile mussels.Proteomic analysis indicated that Cd caused immune stress and disturbances of cytoskeleton and signal transduction,As(V)induced oxidative disruption and disturbances of energy metabolism,apoptosis and gene expression in juvenile mussels,respectively.There were no significant changes in superoxide dismutase(SOD),catalase(CAT),glutathione S-transferases(GST)activities and malondialdehyde(MDA)content in juvenile mussels.3.Toxicological effects of Cd and As(V)on adult musselsAfter exposed to Cd(50 μg/L)and As(V)(50 μg/L)for 48 hours,adult mussels exhibited significant Cd accumulation(p < 0.01)and As accumulation(p < 0.05)in the whole soft tissues.NMR-based metabolomics revealed differential metabolic responses in adult mussels exposed to Cd and As(V).Both Cd and As(V)induced energy disruption and osmotic stress in adult mussels via different pathways.2D electrophoresis and mass spectrometry-based proteomics revealed that Cd caused cytoskeleton disruption in adult mussels.As(V)induced disturbances of gene expression,lipid metabolism,nerve conduction and DNA damage in adult mussels.In summary,the toxicological effects of Cd and As(V)were characterized in three different life stages(D-shape larvae,juvenile and adult)of marine mussels Mytilus galloprovincialis using traditional toxicological methods and high throughput –omic technologies.Basically,the metabolic and protein responses indicated that the D-shape larval mussel was the most sensitive life stage to the Cd and As(V)exposures.Cd caused a dose-dependent effect in D-shape larval mussels.The reduced sensitivity to Cd and As(V)exposures were observed in juvenile mussels.Adult mussels possessed the highest tolerance to Cd and As stresses.With the growth of mussels,the mussels are more tolerant to Cd and As stresses.