Consequences of a multi-generation exposure to uranium on Caenorhabditis elegans life parameters and sensitivity
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The assessment of toxic effects at biologically and ecologically relevant scales is an important challenge in ecosystem protection. Indeed, stressors may impact populations at much longer term than the usual timescale of toxicity tests. It is therefore important to study the evolutionary response of a population under chronic stress. We performed a 16-generation study to assess the evolution of two populations of the ubiquitous nematode Caenorhabditis elegans in control conditions or exposed to 1.1 mM of uranium. Several generations were selected to assess growth, reproduction, survival, and dose–responses relationships, through exposure to a range of concentrations (from 0 to 1.2 mM U) with all endpoints measured daily. Our experiment showed an adaptation of individuals to experimental conditions (increase of maximal length and decrease of fecundity) for both populations. We also observed an increase of adverse effects (reduction of growth and fertility) as a function of uranium concentration. We pointed out the emergence of population differentiation for reproduction traits. In contrast, no differentiation was observed on growth traits. Our results confirm the importance of assessing environmental risk related to pollutant through multi-generational studies.
KeywordsCaenorhabditis elegans Multi-generations experiment Evolutionary ecotoxicology Uranium
We are especially grateful to Catherine Lecomte for discussions and suggestion on this project, Audrey Sternalski for discussion and punctual help, Virginie Camilleri for technical assistance with the ICP-AES measurements, and Cleo Tebby for linguistic corrections, statistical validation and discussion. We also thank Henrique Teotónio for providing us with his base population and for comments. The authors are also grateful to two anonymous reviewers for their valuable comments and suggestions on the manuscript. This work was part of the Envirhom-Eco research program supported by the french Institute for Radioprotection and Nuclear Safety (IRSN) and the 190 DRC-08-02 program supported by the french Ministry of Ecology.
Conflict of interest
The authors declare that they have no conflict of interest.
The experiments comply with the current law of the country in which they were performed.
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