Masculinization by retinoid x receptor (RXR) agonists of gonadic females? genitalia in Pomacea canaliculata (Ampullaridae) at the time of sexual differentiation.

GIRAUD BILLOUD, M; CASTRO-VAZQUEZ, A

San Luis

Congreso; XXXV Annual Meeting of the Cuyo Society of Biology; 2017

Sociedad de Biología de Cuyo

Female masculinization by environmental pollutants has been studied in numerous gastropods, including Pomacea canaliculata, a species native to the Rio de la Plata lower basin, which has invaded many locations in South East Asia, Europe and Pacific islands. Adult female Ampullariidae typically show a clitoris-like ?copulatory apparatus? which grows and develops both during aging and in response to retinoid X receptor (RXR) ligands, as the endogenous 9-cis retinoic acid (9cis-RA) or the xenobiotics tributyltin (TBT) and triphenyltin (TPT). Observations were run during a critical period of development (10 mm-15 mm stages) during which sexual differentiation of the genitalia occurs. For this purpose, 10 mm females were injected with either 9cis-RA, TBT or TPT (1μg/g body mass), or the corresponding vehicle, and sacrificed 2 weeks later, when being about 15 mm long. The length of the female penis (PL) and the development of the distal gland characterizing the female penial sheath were recorded (PSG). Only TBT induced a small but significant increase (Mann-Whitney-test) in PL. The three agonists used provoked a significant development of the PSG (Fisher?s-test: 9cis-RA, control 0%, treated 78%; TBT, control 0%, treated 100%; TPT: control 17%, treated 82%). It is concluded that RXR agonists may control the development of the penial sheath gland at the time of sexual differentiation of the genitalia, while there was no evidence of an action on the PL, except for TBT. However, histological and morphometric studies of the penis are still needed to ascertain if any changes actually occurred.