Differential toxicological effects induced by mercury in gills from three pedigrees of Manila clam Ruditapes philippinarum by NMR-based metabolomics

Abstract

Mercury is a hazardous pollutant in the Bohai marine environments due to its high toxicity to the marine organisms and subsequent ecological risk. Manila clam Ruditapes philippinarum is one of important sentinel organisms in 'Mussel Watch Program' launched in China and therefore used as a bioindicator in marine and coastal ecotoxicology. There are dominantly distributed three pedigrees of clam (White, Liangdao Red and Zebra) in Yantai population endowed with different tolerances to environmental stressors. In this study, gill tissues were collected from both untreated and mercury exposed White, Liangdao Red and Zebra clams, and the extracts were analyzed by NMR-based metabolomics to compare the original metabolomes and the toxicological effects induced by mercury exposure in three pedigrees. The major abundant metabolites in White clam sample were branchedchain amino acids, lactate, alanine, arginine, acetoacetate, glutamate, succinate, citrate, malonate and taurine, while the metabolite profile of Liangdao Red clam sample comprises relative high levels of alanine, arginine, glutamate, succinate and glycogen. For Zebra clam sample, the metabolite profile exhibited relatively high amount of aspartate, acetylcholine and homarine. After 48 h exposure of 20 lg l -1 Hg 2? , the metabolic profiles from all the three pedigrees of clams commonly showed significant increases in alanine, arginine, glutamate, aspartate, a-ketoglutarate, glycine and ATP/ADP, and decreases in citrate, taurine and homarine. The unique metabolic differences between the metabolomes of gill tissues from Hg 2? -exposed White, Liangdao Red and Zebra clams were found, including elevated acetylcholine and branched-chain amino acids in White clams, and the declined succinate in both White and Liangdao Red samples as well as the declined betaine in Zebra and White clams. Overall, our findings showed the differential toxicological responses to mercury exposure and that White clams could be a preferable bioindicator for the metal pollution monitoring based on the metabolic changes from gill compared with other two (Liangdao Red and Zebra) pedigrees of clams.

Effects of hypoxia in the gills of the Manila clam Ruditapes philippinarum using NMR-based metabolomics

“…2). These differences suggested disturbances in osmotic regulation associated with hypoxia, which have also been demonstrated when R. philippinarum is exposed to other stresses, such as salinity irregularity and environmental pollution Liu et al, 2014;Zhang et al, 2011;Liu et al, 2011). The alterations in the amount of these osmolytes reflect an innate response of the clams to balance their intracellular osmolarity with the local environment, as previously demonstrated for other marine organisms (Viant et al, 2003).…”

Metabolic responses in gills of Manila clam Ruditapes philippinarum exposed to copper using NMR-based metabolomics

“…In our previous work, the accumulation of acetylcholine was detected in gill tissues of clam after exposure with mercury that is known as a typical neurotoxic heavy metal (Liu et al, 2011). Elevated acetylcholine was then recognized as the biomarker of neuro-toxicity induced by mercury (Liu et al, 2011). In this work, it seemed copper exposures could induce contrary alteration in acetylcholine to that caused by mercury exposure.…”

“…As a matter of fact, the inhibition of AChE is followed by accumulation of acetylcholine, however, the significant decrease of acetylcholine was detected in clam gills caused by both low and high doses of Cu after 24 h of exposure. In our previous work, the accumulation of acetylcholine was detected in gill tissues of clam after exposure with mercury that is known as a typical neurotoxic heavy metal (Liu et al, 2011). Elevated acetylcholine was then recognized as the biomarker of neuro-toxicity induced by mercury (Liu et al, 2011).…”

Proteomic and metabolomic responses in hepatopancreas of Mytilus galloprovincialis challenged by Micrococcus luteus and Vibrio anguillarum

“…Metabolite extracts of hepatopancreas from mussels were analyzed on a Bruker AV 500 NMR spectrometer performed at 500.18 MHz (at 25°C) as described previously [37]. All 1 H NMR spectra were phased, baseline-corrected, and calibrated (TSP at 0.0 ppm) manually using TopSpin (version 2.1, Bruker).…”