Exploring hypotheses on the mechanisms of imposex induction in Pomacea canaliculata

RODRIGUEZ, C; CASTRO VAZQUEZ, A

Mendoza

Congreso; XXXIV Annual Meeting of the Cuyo Society of Biology; 2016

Sociedad de Biología de Cuyo

Previous studies in this snail have shown the existence of phagocytic hemocytes in the circulation and renal islets, as well as the formation of hemocyte spheroidal aggregates in the kidney and lung after in vivo injection of yeast cells. These aggregates remind the granulomata of human tuberculosis, however lacking the typical lymphocytic rim, which is not surprising since there are no lymphocytes in P. canaliculata, as well as no other evidence of an adaptive immune system. In a preliminary experiment, we have injected 9 adult male P. canaliculata in the visceral mass with 100 cfu of Mycobacterium marinum and have recorded snail mortality and the histopathological changes in the kidney, gill and lung of both surviving and dead snails. Three snails were sacrificed 4 days after injection, while 3 other snails died on days 5-19 after injection. Snails on day 4 after injection showed hypertrophy of the renal islets and spheroid formation within them, accompanied with extensive loss of epithelial cells of the renal cryptae, particularly in the pallial region of the kidney. The gills showed numerous multinuclear cells infiltrating the epithelium of the lamellae, thickening and granulocyte infiltration of the underlying connective tissue and obliteration of the hemocoelic spaces. The lungs were apparently unaffected in day 4-snails, but snails which died between days 9-15 showed atrophic lung walls, with notable depletion of the normal urate tissue. It is suggested that this snail may become a useful animal model for studying the formation of tuberculosis-like granulomata with the participation of the innate immune system only.