Properties of alpha-mannosidase partially purified from the apple snail, Pomacea canaliculata

Integrative Proteomic Analysis of Digestive Tract Glycosidases from the Invasive Golden Apple Snail, Pomacea canaliculata

The freshwater snail Pomacea canaliculata, an invasive species of global significance, possesses a well-developed digestive system and diverse feeding mechanisms enabling the intake of a wide variety of food. The identification of glycosidases in adult snails would increase the understanding of their digestive physiology and potentially generate new opportunities to eradicate and/or control this invasive species. In this study, liquid chromatography coupled to tandem mass spectrometry was applied to define the occurrence, diversity, and origin of glycoside hydrolases along the digestive tract of P. canaliculata. A range of cellulases, hemicellulases, amylases, maltases, fucosidases, and galactosidases were identified across the digestive tract. The digestive gland and the contents of the crop and style sac yield a higher diversity of glycosidase-derived peptides. Subsequently, peptides derived from 81 glycosidases (46 proteins from the public database and 35 uniquely from the transcriptome database) that were distributed among 13 glycoside hydrolase families were selected and quantified using multiple reaction monitoring mass spectrometry. This study showed a high glycosidase abundance and diversity in the gut contents of P. canaliculata which participate in extracellular digestion of complex dietary carbohydrates. Salivary and digestive glands were the main tissues involved in their synthesis and secretion.

Endosymbiotic and host proteases in the digestive tract of the invasive snail Pomacea canaliculata: diversity, origin and characterization

Digestive proteases of the digestive tract of the apple snail Pomacea canaliculata were studied. Luminal protease activity was found in the crop, the style sac and the coiled gut and was significantly higher in the coiled gut. Several protease bands and their apparent molecular weights were identified in both tissue extracts and luminal contents by gel zymography: (1) a 125 kDa protease in salivary gland extracts and in the crop content; (2) a 30 kDa protease throughout all studied luminal contents and in extracts of the midgut gland and of the endosymbionts isolated from this gland; (3) two proteases of 145 and 198 kDa in the coiled gut content. All these proteases were inhibited by aprotinin, a serine-protease inhibitor, and showed maximum activity between 30°C and 35°C and pH between 8.5 and 9.5. Tissue L-alanine-N-aminopeptidase activity was determined in the wall of the crop, the style sac and the coiled gut and was significantly higher in the coiled gut. Our findings show that protein digestion in P. canaliculata is carried out through a battery of diverse proteases originated from the salivary glands and the endosymbionts lodged in the midgut gland and by proteases of uncertain origin that occur in the coiled gut lumen.

Mining Invertebrate Natural Products for Future Therapeutic Treasure

This review focuses on biologically active entities from invertebrate sources, especially snails. The reader will encounter several categories of compounds from snails including glycosaminoglycans, peptides, proteins (glycoproteins), and enzymes which possess diverse biological activities. Among glycosaminoglycans, acharan sulfate which was isolated from a giant African snail Acahtina fulica is reviewed extensively. Conotoxins which are also called conopeptides are unique peptide mixtures from marine cone snail. Conotoxins are secreted to capture its prey, and currently have the potential to be highly effective drug candidates. One of the conotoxins is now in the market as a pain killer. Proteins as well as glycoproteins in the snail are known to be involved in the host defense process from an attack of diverse pathogens. Carbohydrate-degrading enzymes characterized and purified in snails are introduced to give an insight into the applicability in glycobiology research such as synthesis and structure characterization of glycoconjugates. It seems that simple snails produce very complicated biological compounds which could be an invaluable source in future therapeutics as well as research areas in natural medicine.