Developmental and Persistent Toxicities of Maternally Deposited Selenomethionine in Zebrafish (Danio rerio)

The objectives of this study were (1) to establish egg selenium (Se) toxicity thresholds for mortality and deformities in early life stages of zebrafish (Danio rerio) after exposure to excess selenomethionine (SeMet, the dominant chemical species of Se in diets) via in ovo maternal transfer and (2) to investigate the persistent effects of developmental exposure to excess SeMet on swim performance and metabolic capacities in F1-generation adult zebrafish. Adult zebrafish were fed either control food (1.3 mu g Se/g, dry mass or d.m.) or food spiked with increasing measured concentrations of Se (3.4, 9.8, or 27.5 mu g Se/g, d.m.) in the form of SeMet for 90 d. In ovo exposure to SeMet increased mortality and deformities in larval zebrafish in a concentration-dependent fashion with threshold egg Se concentrations (EC10s) of 7.5 and 7.0 mu g Se/g d.m, respectively. Impaired swim performance and greater respiration and metabolic rates were observed in F1-generation zebrafish exposed in ovo to 6.8 and 12.7 mu g Se/g d.m and raised to adulthood in clean water. A species sensitivity distribution (SSD) based on egg Se developmental toxicity thresholds suggests that zebrafish are the most sensitive fish species studied to date.