Effects of dietary uranium on reproductive endpoints—fecundity, survival, reproductive success—of the fish Danio rerio

Abstract

Exposure to metal-contaminated water has been shown to result in a number of reproductive abnormalities in adult and larvae fish, such as failure of oocyte maturation and teratogenic effects. Recently, dietary uptake of metals by fish has been recognized as a critical route of exposure, however, the mechanisms of metal uptake and toxicity are poorly understood and in need of further investigation. The objectives of the present study are to quantify uranium (U dietary transfers from spiked artificial diets) in Danio rerio tissues and embryos, as well as establish its effect on reproduction and embryonic development. Uranium's environmental prominence is currently increasing because of new mining and milling activities. Uranium concentrations range from 0.02 µg/L in natural waters to 2 mg/L. The focus of this study was to examine the trophic transfer and effects of U following exposure modalities (dose, exposure duration 1 to 20 d). Two different isotopes were used to distinguish between chemical and radioactivity toxicity of U. Results showed that U trophic transfer was low (0.52%). Uranium tissue distributions showed that accumulation occurred in digestive organs (liver, digestive tract) following dietary exposure. High levels of U were measured in the gonads (female in particular, >20% of relative burden). High U accumulation levels in eggs indicated maternal transfer of the contaminant. Moreover, U trophic exposure led to a reduction in reproduction success as a function of U accumulated levels. High U exposure conditions strongly reduced the total number of eggs (50%) and their viability at 10 d (reduction of the clutch number, low quality of eggs).

Relative importance of direct and trophic uranium exposures in the crayfish Orconectes limosus: Implication for predicting uranium bioaccumulation and its associated toxicity

“…(Note that postmolted crayfish were eliminated from the experiments.) No effects on the predation behavior were observed in the fish Coregonus clupeaformis after 100 d trophic exposure (four doses of uranium in an artificial diet) [25] or in the fish Danio rerio after 20 d trophic exposure (two doses of uranium in an artificial diet: 50 and 500 mg/g) [8].…”

“…Evidence was seen of trophic transfer of uranium to gills, and this was certainly linked to physiological properties (highly perfused organ) and participation in excretory metabolism [45]. Accumulation in the gill after metal trophic transfer was observed in fish [8,25,46], and in the crustacean [2,47,48]. The transport via hemolymph may, however, be low.…”

“…Ecological risk assessments often focus on the relationship between direct exposure and the associated effects, but many standard toxicology tests do not take trophic exposure into account, even though trophic exposure in controlled conditions is easy to reproduce and interpret as direct exposure standardized tests [8].…”

“…In crayfish, uranium can impair mitochondrial function and induce oxidative stress [23]. Very few studies have focused on its accumulation and associated toxic effects after trophic exposure [8,[25][26][27]. The ecotoxicological profile of uranium is not yet fully understood, and the major pathway responsible for its accumulation levels has not yet been determined.…”

Effects of uranium on the metabolism of zebrafish, Danio rerio

“…Uptake can also occur through food and also be transferred maternally to offspring (Simon et al, 2011). In experimental settings, as analysed here, food (Tetramin TM ) is not spiked but may contain background levels of U (≈2.6 nmol U g −1 Tetramin TM , K. Faucher pers.…”