IHEM   20887
INSTITUTO DE HISTOLOGIA Y EMBRIOLOGIA DE MENDOZA DR. MARIO H. BURGOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Exploring hypotheses on the mechanisms of imposex induction in Pomacea canaliculata.
Autor/es:
MANGIONE, RJ.; CASTRO-VAZQUEZ, A.; GIRAUD BILLOUD, M.
Lugar:
Mendoza
Reunión:
Congreso; XXXIV Reunión científica de la Sociedad de Biología de Cuyo; 2016
Institución organizadora:
Sociedad de Biología de Cuyo
Resumen:
Imposex (superimposition of male sexual characters onto females) has been described in more than 250 gastropod species exposed to different ?endocrine disruptors? (EDs). Three main hypotheses have been postulated for the induction of the mechanisms involved in imposex development: (1) Steroids (ST), (2) Neuroendocrine peptides (NE) and (3) Agonist/s in the retinoid X receptor pathways (RXR-p) and depending pathways. ?ST? postulates an imbalance in steroid hormones characterized by higher testosterone levels, while ?NE? proposes that homeostasis of neuroendocrine factors (as the APGWamide peptide) can be disrupted by EDs. Finally, ?RXR-p? proposes that EDs mimic ligands of homodimers or heterodimers of RXR, and thus induce the development of imposex. We have previously shown in adequately controlled conditions that P. canaliculata females exposed in water to tributyltin (TBT, the most widely studied ED) results in imposex development and, in the present study, we explored the possible mechanisms underlying this phenomenon. We evaluated imposex in 4-months old females treated (i.m.) with 1 µg per g of drained body mass of testosterone, androstenedione, APGWamide, 9-cis retinoic acid (9-RA, a proposed endogenous RXR agonist) and rosiglitazone (an agonist of PPARγ, a receptor in the RXR pathways) compared to control groups (vehicle-injected) or TBT-treated females. Snails were sacrificed 4 weeks later, the length of the penial sheath and the penis were measured and an ?index of phallic development? was determined. We found a significant increase in the quantified parameters in 9RA-treated group and the results were similar to those obtained in TBT-treated females. Our results are in agreement with a central role of the RXR in imposex induction in P. canaliculata.