BioProject

Organotin compounds are highly persistent organic pollutants that bioaccumulate in marine biota, behaving as potent endocrine disruptors. More...

Organotin compounds are highly persistent organic pollutants that bioaccumulate in marine biota, behaving as potent endocrine disruptors. Tributyltin (TBT) has been described as an environmental obesogen, as it contributes in mammals to lipid accumulation in a mechanism mediated by PPARγ and RXR. With the aim of studying the molecular mechanisms that elicit TBT-induced pathogenesis in fish, thicklip grey mullets Chelon labrosus were exposed to low (10 ng/L) and high (500 ng/L) TBT concentrations for 1, 7 and 21 days, and gene transcription and metabolome profiles were studied. With this purpose, the multitissue transcriptome of mullet was sequenced by 454 pyrosequencing obtaining 126 Mb of sequence information. Assembly and annotation allowed spotting 8330 gene signatures on an oligonucleotide microarray that was used to identify hepatic gene transcription profiles specific to each TBT exposure set-up. Functional pathway analysis revealed that early profiles were characterized by genes related to response to organic substances and to oxidative stress and glucose metabolic processes. After 21 days of exposure, enriched GO terms in both concentrations were related to lipid homeostasis with a significant regulation of steroid metabolic and cholesterol biosynthetic processes. Also, the androgen receptor signalling pathway was regulated while PPAR signalling appeared as the most significantly regulated KEGG pathway. Neutral lipid accumulation measured by Oil-Red-O histochemistry did not show any treatment-related effect but hepatic and plasma NMR and GC-MS metabolomic analysis revealed distinctive metabolites. Aqueous profiles were characterised by lactate, glucose and alanine while GC-MS revealed a whole set of discriminating polyunsaturated fatty acids. Thus, TBT pathogenesis involves alterations of lipid metabolism through a mechanism that could involve PPARγ-regulated processes confirming the obesogen hypothesis for TBT in fish. Overall design: Thicklip grey mullets were exposed to tributyltin (TBT). 3 treatments: control, TBT low dose (10ng/L), TBT high dose (500ng/L); 3 sampling times: 1 day, 1 week, 3 weeks. 6 mullets were dissected in each sampling point and group. Less...