Biometric data assessment on Xenopus laevis tadpoles

Recent studies stated that 41% of known species of amphibians are threatened.1 Indeed, their dramatic population decline is due to environmental conditions, including pollution.2,3 Their permeable skin and their close relationship with aquatic compartment, make them particularly sensitive to contamination and stand as strong models in biomonitoring studies.4 Consequently, the use of biomarkers in batrachians arose in the 80’s5: from morphological and anatomical approaches (deformities, gonadic abnormalities) to biochemical measurements (vitellogenin, methallothionein, CYP450).4 For example, embryotoxic and teratogenic damages on larvae were detected with the FETAX (Frog Embryo Teratogenesis Assay - Xenopus) test developed in Xenopus laevis.6-8 In this regard, this specie appears as a very effective laboratory model for assays to dissect actions of chemical contamination. Indeed, profusion of data is available in cell cycle, embryology and development fields.9-11 Moreover, our recent studies showed some different sub-individual modifications, especially a decrease of oocytes’ capacity to perform the maturation and the fertilization in presence of cadmium.12,13 Here, we propose new methods to quantify the impacts of chemical contaminants on Xenopus laevis young tadpoles by recording biometric criteria.