Antidigestive and antinutritive properties of the albumen gland of the invasive snail Pomacea canaliculata (Gastropoda: Ampullariidae)

CADIERNO MARÍA PILAR, DREON MARCOS SEBASTIÁN, HERAS HORACIO

La Serena

Congreso; Physiomar-14; 2014

Centro de Estudios Avanzados en Zonas Áridas

Pomacea canaliculata (Lamark, 1822) is an amphibious freshwater South American species that represents a serious crop pest on introduced areas. As an intermediate host of the parasite Angiostrongylus cantonensis, its invasion is also associated with the spreading of the angiostrongyliasis . The female reproductive tract includes an accessory organ, called albumen gland (AG), that provides fertilized oocytes with a perivitellin fluid. AG`s secretions include a series of multifunctional proteins. The most abundant ones are PcOvo and PcPV2, which display antinutritive and neurotoxic properties respectively, presumably involved in embryo defenses against predators. Though it was unknown if these defenses are already biologically active inside the gland. If active, these proteins could help to explain the behaviour of predators of invariably discarding the gland when feeding on P. canaliculata females. In this regard, we have recently tested the neurotoxic effect of the AG´s soluble fraction and found it has a lethal effect when it is intraperitoneally administrated on mice (unpublished data). In the present study we tested the antidigestive effect of the soluble fraction of the AG and the antinutritive effect of PcOvo and PcPV2 isolated from this organ. To that aim, a trypsin inhibition assay (TIA) was carried on by mesuring the enzimatic activity spectrophotometrycally. Besides, an in vitro simulated gastrointestinal digestion was performed with purified PcOvo and PcPV2. The TIA showed that AG`s soluble fraction is able to inhibit the trypsin activity. Purified proteins were resistant to in vitro gastroinestinal digestion for at least 120 min showing no change in electrophoretic movility along the simulated digestion process. These indicate that the gland stores the egg proteins already in a biologically active conformation. Considering the neurotoxicity of the gland, its capacity to inhibit digestive proteases and the fact that their most abundant storage proteins are resistant to gastrointestinal digestion, the AG could be considered as a toxic, antinutritive and antidigestive organ. This provides a possible explanation of the already mentioned behaviour of adult female apple snail predators.