HIGHLIGHTS

• Fluctuations in the retinoid profile (vitamin A and analogues) during the development of A. mellifera and G. fossarum;
• Evaluating the role of retinoic acid in development (morphogenesis and reproduction);
• Mediation of retinoids in the occurrence of developmental abnormalities following exposure to phytosanitary substances.

Abstract

The presence of pesticides in both terrestrial and aquatic ecosystem compartments is of significant concern for non-target wildlife species. The use of biomarkers allows an effective biomonitoring and points out early imbalances in these organisms. Retinoids (RETs, vitamin A and their derivatives) are essential compounds for vertebrates and are used as biomarkers to assess the chemical pressure in ecosystems. Several studies suggested the involvement of retinoic acid (RA, active form of vitamin A) in the development and reproduction of arthropods. In order to establish the potential of RETs in view of biomarkers development, we studied two arthropods, the gammarid Gammarus fossarum (crustacean) and the honey bee Apis mellifera (insect). The obectives orour study was to 1) identify and measure the RETs of these models, 2) study the involvement of AR in reproduction and development, and 3) evaluate the effects of pesticides on the RETs and on these two functions in G. fossarum and A. mellifera. A new analytical method (UHPLC-MS/MS) allowed the observation of a decrease in the RET precursors retinaldehyde (RALD) and retinol (ROL) during the reproduction of G. fossarum and the development of A. mellifera, respectively, as wel as an increase in RA metabolites. The upward and downward fluctuations in RA concentrations affected the growth of bees and the oogenesis, embryogenesis and molting of gammarids following exposure to AR and citral (CIT, a RA synthesis inhibitor) suggesting endogenous functions of RA in these arthropods. Exposure to MET altered the RA isomers ratio in G. fossarum which may be associated with the observed effects on oogenesis and molting. Exposures to MET and GLY induced disturbances in the bee’s RETs (larvae, pupae, and adults), but only MET interfered with its development. The results suggest an involvement of RA in the reproduction and molting of G. fossarum and in the development of A. mellifera. Here, we demonstrate that the RETs system of these models is influenced by the presence of pesticides. These results open a research avenue for RET-based biomarkers in arthropods.

PUBLICATIONS AND COMMUNICATIONS

• Gauthier, M., Aras, P., Jumarie, C. & Boily, M. Low dietary levels of Al, Pb and Cd may affect the non-enzymatic antioxidant capacity in caged honey bees (Apis mellifera). Chemosphere 144, 848–854 (2016).
• Gauthier, M., Aras, P., Paquin, J. & Boily, M. Chronic exposure to imidacloprid or thiamethoxam neonicotinoid causes oxidative damages and alters carotenoid-retinoid levels in caged honey bees (Apis mellifera). Sci. Rep. 8, 1–11 (2018).
• Au cours de ma formation, j’ai eu l’occasion de communiquer les résultats de mes travaux dans de nombreux congrès et colloque spécialisés au Québec (Colloque du Groupe de recherche en toxicologie de l’environnement de l’UQAM Congrès de l’association Francophone pour le savoir, Chapitre Saint-Laurent (SETAC-SRA), colloque de l’Association pour la recherche au collégial, etc.). Parallèlement, j’ai aussi donné quelques conférences grand public notamment pour le lancement de l’Alliance pour l’interdiction des
• pesticides systémiques (AIPS), Miel Montréal et le Cégep de Saint-Laurent. Mes travaux ont aussi été présentés en France dans le cadre du Congrès du Groupe français des pesticides et aux journées de la recherche apicole de l’Institut technique et scientifique de l’apiculture et de la pollinisation (ITSAP).

Cite the thesis

Maxime Gauthier. Implication de l’acide rétinoïque dans la reproduction et le développement et perturbations par des pesticides chez le gammare (Gammarus fossarum) et l’abeille domestique (Apis mellifera). Sciences du Vivant [q-bio]. Université Claude Bernard - Lyon I; Université du Québec à Montréal, 2023. Français. ⟨NNT : 2023LYO10072⟩. ⟨tel-04577390⟩

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