Proteomic Response of the Freshwater Crustacean Hyalella azteca to the Estrogenic Contaminant 17β-Estradiol: An Exploratory Ecotoxicological Study

Estrogenic endocrine-disrupting chemicals (EDCs) are among the most pervasive contaminants in freshwater systems. Benthic amphipods live in direct contact with these agents and support the aquatic food web, yet molecular tools to detect and characterize responses to estrogenic exposure remain largely undeveloped or unvalidated, which limits their use for monitoring and risk assessment. The recent genome sequencing of Hyalella azteca (H. azteca), a key food-web species, enables proteomic approaches to help close this gap. Here we report the first exploratory, genome-enabled, whole-organism proteomics study of the response of this crustacean to the estrogenic EDC 17β-estradiol (E2) in both sexes at a nominal concentration of 100 ng/L. Using nanoflow liquid chromatography–tandem mass spectrometry, we profiled protein expressions in both sexes following acute exposure. Differentially expressed proteins were mapped to more than 100 canonical pathways by Ingenuity Pathway Analysis®. The most enriched pathways, related mainly to protein quality control, intracellular trafficking, and carbohydrate metabolism, differed in predicted direction between sexes, with directional predictions reaching the confidence threshold mainly in males. These results demonstrate the feasibility of proteomics-based molecular profiling of E2 exposure in H. azteca, extending beyond conventional phenotypic toxicity testing. As a hypothesis-generating dataset, our results provide a foundation for targeted validation, time-course and dose–response studies for candidate protein markers, as well as testing whether these responses extend across estrogenic EDCs.