An Arsenic-76 radiotracer to study the routes of assimilation, hemolymph distribution, and tissue inventories in the bioindicator organism Pomacea canaliculata

ISRAEL A. VEGA; JUAREZ, ANDREA; MAYORGA, LUIS S.; ARRIBERE ; GUEVARA, SERGIO RIBEIRO

Mar del Plata

Congreso; VIII Congreso Argentino de la Sociedad de Toxicología y Química Ambiental.; 2022

The freshwater gastropod Pomacea canaliculata (Gastropoda: Ampullariidae) fulfills the ideal conditions of a bioindicator species and is widely distributed in the Chaco-Pampeana region of Argentina, where there are many aquatic ecosystems potentially affected by hydroarsenicism. The aim of this work was to analyse the absorption, distribution through the hemolymph, and bioaccumulation of arsenic (As) by the bioindicator P. canaliculata using a short-lived tracer (76As, t1/2: 1.07 d) with high specific activity. The As2O5 was irradiated for 4 h in the RA-6 experimental reactor of the Bariloche Atomic Center (Argentina). Aliquots of the radioisotope 76As standard solution were used to inoculate snails, water, or food. All samples were placed in test tubes and then counted employing a gamma spectrometry system, consisting in a well type-High Purity Germanium (HPGe) detector (ORTEC GWL-90-15 HPGe®), a DSPec® spectrometer and Maestro software. As travels mainly dissolved in the plasma of the snail´s hemolymph. This element is transferred from the hemolymph to the tissues (87 %) 4 h after the inoculation of 50 µL of a 0.04 g/L of 76As radiotracer solution, being the digestive gland, kidney, and head-foot the main places of arsenical inventories. Snails exhibited a rapid As accumulation response in a wide range of concentrations (from 1 to 1,000 µg/L) of the metalloid dissolved in water and in a concentration-dependent manner. Also, snails incorporated As from the digestive system when they received a single safe dose of ~ 2 µg of 76As inoculated in a fish food pellet. The (semi) physiologically based toxicokinetic model developed in this study is based on anatomical and physiological parameters (blood flow, irrigation, and tissue volume). Together, these findings make P. canaliculata an excellent sentinel organism to evaluate freshwater bodies naturally contaminated with As.