Identification of molt-inhibiting hormone and ecdysteroid receptor cDNA sequences in Gammarus pulex, and variations after endocrine disruptor exposures

PCR amplification allowed to obtain 204 bp length and 255 bp length fragments, encoding for partial sequences of 68 amino acids and 85 amino acids, which correspond to EcR and MIH, respectively, and which are highly conserved in crustacean species. Results highlighted MIH and EcR expressions mainly in G. pulex head, which is the localization of XO and YO. Moreover, irrespective of the EDC exposure, increases of MIH and EcR relative expressions were observed, as it was observed after the exposure to 20-hydroxyecdysone (20HE), the natural molt hormone, used as positive control. Therefore, it appeared that tested EDCs behaved like 20HE, suggesting that their effects could occur through the ecdysteroids pathways, and so impact the molt process of G. pulex on the long term. Finally, the present study is a first step in the possibility of using MIH and EcR relative expressions as biomarkers of exposure for EDCs risk assessment. However additional studies must first be carried out to better characterize and understand their variations, and also better predicted consequences for the exposed amphipods.