Alteration of heart tissue protein profiles in acute cadmium-treated scallops Patinopecten yessoensis.

Cadmium (Cd) is an extremely toxic metal that induces a wide spectrum of toxic responses in organisms in the environment. In the present study, scallops (Patinopecten yessoensis), after acclimation for 1 week in the laboratory, were subjected to acute Cd chloride (CdCl₂) toxicity, and ultramorphological and proteomic changes in their heart tissues were analyzed and compared with those of the nonexposed control group. Electron microscopy showed that ultrastructures of the cytoplasm and mitochondria in scallop hearts were badly damaged, and two-dimensional gel electrophoresis showed 32 protein spots that were differentially expressed after exposure to 10 mg/l CdCl₂ for 24 h. Of these spots, 8 were upregulated, 16 were downregulated, and 8 showed low expression. Proteins from these spots were identified using matrix-assisted laser desorption/ionization-time of flight mass spectrometry and database searching. The results indicated that these proteins are involved in the regulation of cell structure, transport, signal transduction, and metabolism. Among other things, four proteins-identified as amino acid adenosine triphosphate (ATP)-binding cassette transporter, glycerol-3-phosphate dehydrogenase (nicotinamide adenine dinucleotide phosphate), nicotinamide adenine dinucleotide oxidase, and ATPase-were demonstrated to be especially associated with Cd toxicity. Some of the other proteins observed in this work are of particular interest in terms of their responses to Cd, which have not been reported previously. These data may provide novel biomarkers for monitoring the Cd contamination level of flowing seawater as well as provide useful insights into the mechanisms of Cd toxicity.