Use of Early Life-Stages of Zebrafish to Assess Toxicity of Sediments Contaminated by Organotin Compounds

This study examined the response of early life-stages (ELS) of zebrafish to organotin-contaminated sediment from Lake Huruslahti (HL) in Central Finland. A dilution series (0, 10, 33, and 100%) of the native (HL) and the sediment spiked with tributyltin (TBT) determined a dose-response of zebrafish ELS to organotin-contaminated sediment. Sediment elutriates were assessed by bacterial bioluminescence assay and microscopical pathologies of 1–3 days post-fertilization zebrafish (1–3dpfZF). Brain aromatase (cyp19a1b) and tissue vitellogenin (vtg1) were assayed from early-juvenile zebrafish (20dpfZF) exposed to intact sediment. In vivo modulation of cyp19a1b and vtg1 transcripts in 20dpfZF was targeted to screen potential sediment contamination by TBT, an anti-estrogenic chemical. Bioluminescence assay (EC50_{30min =} 34.6% of HL-100) determined that the HL-100 elutriate was toxic. Exposed developing embryos (1–3dpf) showed toxicities, including lowered heart rate. Results showed down-regulation of cyp19a1b and up-regulation of vtg1 in 20dpfZF exposed to TBT-spiked sediment (185–1620 µg/kg d.w.).