Composition and toxicity of the egg of Pomacea maculata Perry, 1810

GIGLIO, M.; ITUARTE S,; HERAS, H

La Serena

Conferencia; 5th Physiomar; 2014

CEAZA

Pomacea maculata (Gastropoda:Ampullariidae), also called ?apple snail?, is a freshwater South American species, and is one of the most destructive ampullariid of aquatic crops in its invaded range. Like other species from the Pomacea genus, they deposit their eggs above the waterline on vegetation and rocks in calcareous and brightly colored clutches; coloration is probably a warning signal of their defenses. This remarkable egg-laying strategy exposes the eggs to harsh conditions such as high temperatures, desiccation and terrestrial predators. Among the adaptations to cope with these conditions is the provision of eggs with a perivitelline fluid surrounding embryos that acts as their nutrition and protective source. Egg composition was only partially determined in P.canaliculata. In this species carbohydrates are the major nutrient representing 34.8% (dry weight), followed by proteins (13.0% dry weight) and structural lipids (1.5% dry weight). In the last case, it was determinated that the major components were free sterols (ST) and phosphatidylethanolamine (PE). The major protein fractions are three: a red colored one called PcOvo (or PcPV1), an orange colored and complex one called, PcPV3, and a third one uncolored between those knowns as PcPV2. Previous studies demonstrate indicate that PcOvoPV1 acts as a fotoprotective, antioxidant and trypsin inhibitor component in eggs, apart from providinge it with the pink-reddish coloration, while the PcPV2 showed a neurotoxic activity (DL50=0.25 mg/Kg) in mice when the protein was administeredprovide via intraperitoneal and generate imnmune response when when ingested in sublethal amountsorally. The functions of the PcPV3 fraction are not completely elucidated yet. Recent studies in P. maculata only focusedprovide information abouton the composition of the protein fraction of the PVF. Similar to P. canaliculata, the PVF showed 3 protein fractions with similar properties and so called PmPV1, PmPV2 and PmPV3. Till the moment, only Tthe PmPV1 fraction was the only one studied so far, showing the same functions as PcPV1. In the present work we study the composition of P. maculata?s eggs and the neurotoxic activity of the protein PmPV2 (equivalent to PcPV2). Egg clutches s were obtained in the laboratory wereand homogeneized in using Tris-HCl 20mM buffer (pH=7.0) with a buffer:sample ratio 3:1 v/v . The amount of carbohydrates, proteins and lipids were determinedobtained bythrough the routine assays: van Handel (1965), Markwell (1978) and Bligh & Dyer (1959), respectively. Toxicity was first checked for perivitelline fluid by administering XXmg of total protein to BALB/c mice by intraperitoneal injection. Then, a lethal dose (LD50) was calculated for purified PmPV2 by injecting different doses of the protein and contabilizing deaths after 96 h.