Histopathological effect and stress response of mantle proteome following TBT exposure in the Hooded oyster Saccostrea cucullata

Tributyltin (TBT), an environmental pollutant in marine ecosystems, is toxic to organisms. Although contamination by and bioaccumulation and toxicity of this compound have been widely reported, its underlying molecular mechanisms remain unclear. In the present study, we exposed the Hooded oyster Saccostrea cucullata to TBT to investigate histopathological effects and proteome stress response. Animals were exposed to three TBT sub-lethal concentrations, 10, 50 and 150 μg/l for 48 h. TBT produced stress leading to histopathological changes in oyster tissues including mantle, gill, stomach and digestive diverticula. TBT induced mucocyte production in epithelia and hemocyte aggregation in connective tissue. Cell necrosis occurred when exposure dosages were high. Comparative proteome analyses of mantle protein of oysters exposed to 10 μg/l and control animals were analyzed by a 2-DE based proteomic approach. In total, 32 protein spots were found to differ (p < 0.05). Of these, 17 proteins were identified which included 14 up-regulated and 3 down-regulated proteins. TBT induced the expression of proteins involved in defensive mechanisms (HSP-78, HSP-70, aldehyde dehydrogenase and catalase), calcium homeostasis (VDAC-3), cytoskeleton and cytoskeleton-associated proteins, energy metabolism and amino acid metabolism. Our study revealed that TBT disturbs calcium homeostasis via VDAC-3 protein in mantle and this probably is the key molecular mechanism of TBT acting to distort shell calcification. Moreover, proteins involved in cell structure (tubulin-alpha and tubulin-beta) and protein synthesis were reduced after TBT exposure. Additionally, differential proteins obtained from this work will be useful as potential TBT biomarkers. - Highlights: • TBT produced histopathological changes in the Hooded oyster tissues as dose and time dependent manner. • TBT disturbed proteins with regard to calcium homeostasis, defensive mechanism, cytoskeleton and energy metabolism. • TBT disturbed calcium homeostasis via VDAC-3 protein in mantle and this probably is the key mechanism of TBT to distort shell calcification. • Differential proteins obtained will be useful as potential TBT biomarkers in contamination monitoring program. - TBT produced histopathological changes in oyster tissues and disturbed proteins with regard to calcium homeostasis, defensive mechanisms, cytoskeleton and energy metabolism.