| Summary: | 碩士 === 中國醫藥大學 === 生態暨演化生物學研究所碩士班 === 99 === In order to understand the metal accumulation and detoxification in tilapia (Oreochromis mossambicus) under various chronic copper (Cu) exposures, we investigated the subcellular distributions of Cu. The tilapia were exposed to 0, 0.1, 0.3, and 0.6 ?慊 ml-1 Cu for 28 days followed by a depuration biosaays of 7 days in water. The relative Cu distribution between the metabolically active pool (MAP) and the metabolically detoxified pool (MDP) were analyzed. The biokinetic parameters, including uptake rate (ku), elimination rate (ke), detoxification rate (kd), and bioconcentration factor (BCF) were obtained. The results revealed that as the concentration of Cu increasing in water, the Cu was transferred from MAP to MDP and the ku of liver was decreased to reduce the toxicify arise from Cu accumulation. Copper was stored mainly at metal-rich granules (MRG) in the gill and muscle. The Cu residue was reduced by increasing ke of gill and muscle, and decreasing ku of gill. The relationship between growth inhibition and Cu residues in organ-specific subcellular fractions were significantly related to cell debris, organelle, heat denature protein (HDP), trophically available fraction (TAF), MAP and MDP in the liver. We found that MAP in the liver can be an indicator for predicting growth toxicity in medium to high exposure concentrations (p<0.05). In conclusion, the subcellular regulation of metal toxicity in tilapia play a key role in mediating the chronic Cu toxicity and provide a basic understanding for field ecological exposure risk assessment.
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