Effects of uranium on the metabolism of zebrafish, Danio rerio

Abstract

The increasing demand for nuclear energy results in heightened levels of uranium (U) in aquatic systems which present a potential health hazard to resident organisms. The aim of this study was to mechanistically assess how chronic exposure to environmentally relevant concentrations of U perturbs the complex interplay between feeding, growth, maintenance, maturation and reproduction throughout the life-cycle of an individual. To this end we analysed literature-based and original zebrafish toxicity data within a same mass and energy balancing conceptual framework. U was found to increase somatic maintenance leading to inhibition of spawning as well as increase hazard rate and costs for growth during the early life stages. The fish's initial conditions and elimination through reproduction greatly affected toxico-kinetics and effects. We demonstrate that growth and reproduction should be measured on specific individuals since mean values were hardly interpretable. The mean food level differed between experiments, conditions and individuals. This last 'detail' contributed substantially to the observed variability by its combined effect on metabolism, toxic effects and toxico-kinetics. The significance of this work is that we address exactly how these issues are related and derive conclusions which are independent of experimental protocol and coherent with a very large body of literature on zebrafish eco-physiology.

Zebrafish exposure to environmentally relevant concentration of depleted uranium impairs progeny development at the molecular and histological levels

“…Our data show that chronic exposure to low dose of DU increases oxidative stress, and suggest that it may induce DNA double-strand breaks, and genomic instability in the zebrafish. These genotoxic effects lead to the increases of somatic maintenance costs [25] and could foster the emergence of cancers and metabolic diseases in both the exposed individuals and in their progeny. We show that DU alters the genetic networks regulated by the upstream regulator egr1 , a transcription factor deregulated upon carcinogenesis and involved in the response to oxidative stress and the cell-adhesion process.…”

“…Dissection of brain, ovaries and testis was conducted under the binocular (Leica, France). The main entry of uranium in the body is through the gills [25]. The DU-bioaccumulation in brain, gonads, two-cells stage embryos and 96 hpf larvae was analysed on mineralized samples using a 7500Cx spectrometer (ICP-MS, Agilent) with a detection limit of 0.11 ng/L.…”

Energy-based modelling to assess effects of chemicals on Caenorhabditis elegans: A case study on uranium

“…This result is consistent with other experimental and modelling studies which tackled the mode of action of uranium. Augustine et al (2012a) showed that the mode of action of uranium on Danio rerio could either be assimilation or maintenance. A complementary study reveals that uranium induced an increase of damage in gut cell mitochondria, a loss of the gut wall architecture, the presence of large necrotic zones, and an overall decrease in gut bacteria (Augustine et al, 2012b).…”

“…Such models can be used to assess physiological modifications (e.g. changes in growth rate, maximal length, reproduction rate, cumulated reproduction) (Augustine et al, 2012a;Billoir et al, 2008a;Massarin et al, 2011), or differential life strategy responses (Alda Ál-varez et al, 2005) of an organism exposed to a pollutant. DEB modelling can also be adapted to other types of analysis.…”

Adsorption of uranium(VI) from aqueous solution using a novel magnetic hydrothermal cross-linking chitosan

“…The uranyl ion is linear and has great potential to complex organic ligands, resulting in water solubility resultants [3,4]. These products easily gets into human ecosystem owning to unique mobility, causing irreversible damage by radioactive and chemical toxicity [5,6]. For this sake, uranium separation from uranium containing wastewater is of great importance.…”