Tissue-specific molecular and cellular toxicity of Pb in the oyster (Crassostrea gigas): mRNA expression and physiological studies.
Lead (Pb) is one of the ubiquitous and toxic elements in aquatic environment. In oysters, gills and digestive glands are the main target organs for Pb-induced toxicity, but there is limited information on the molecular mechanisms underlying its toxicity. The present study investigated the Pb-induced toxicity mechanisms in the Pacific oyster (Crassostrea gigas) based on transcriptome, phenotypic anchoring, and validation of targeted gene expression. Gene ontology and pathway enrichment analyses revealed the differential Pb toxicity mechanisms in the tissues. In the gills, Pb disturbed the protein metabolism, with the most significant enrichment of the "protein processing in endoplasmic reticulum" pathway. The main mechanism comprised of a Pb-stimulated calcium (Ca2+) increase by the up-regulation of transporter-Ca-ATPase expression. The disturbed Ca2+ homeostasis then further induced high expressions of endoplasmic reticulum (ER) chaperones, leading to ER stress in the oysters. Unfolded proteins induced ER associated degradation (ERAD), thereby preventing the accumulation of folding-incompetent glycoproteins. However, Pb mainly induced oxidative reduction reactions in the digestive gland with high accumulation of lipid peroxidation products and high expression of antioxidant enzymes. Further, Pb induced fatty acid β-oxidation and CYP450 catalyzed ω-oxidation due to increased metabolic expenditure for detoxification. The increased content of arachidonic acid indicated that Pb exposure might alter unsaturated fatty acid composition and disturb cellular membrane functions. Taken together, our results provided a new insight into the molecular mechanisms underlying Pb toxicity in oysters.
['Meng|Jie|J|', 'Wang|Wen-Xiong|WX|', 'Li|Li|L|', 'Zhang|Guofan|G|']
D000818:Animals D000975:Antioxidants D049896:Crassostrea D059865:Endoplasmic Reticulum Stress D060746:Endoplasmic Reticulum-Associated Degradation D005227:Fatty Acids D020869:Gene Expression Profiling D005786:Gene Expression Regulation D005880:Gills D007854:Lead D015227:Lipid Peroxidation D009928:Organ Specificity D010084:Oxidation-Reduction D018384:Oxidative Stress D012333:RNA, Messenger D059467:Transcriptome D014874:Water Pollutants, Chemical
Crassostrea Transcriptome ER stress Pb exposure Fatty acid oxidation