22. Is there any intestinal protease activity in the digestive system of the apple-snail Pomacea canaliculata?

GODOY, SM, VEGA, IA., CASTRO-VAZQUEZ

Uspallata, Mendoza

Congreso; XXIII Reunión Anual de la Sociedad de Biología de Cuyo; 2005

Sociedad de Biología de Cuyo

The last decades have seen an increasing interest in the biology of this invasive snail. However, its digestive physiology has remained virtually unexplored. In the 1950’s and 60’s, both Meenakshi and Andrews were unable to detect any protease activity in the snail’s gut and hypothesized that nitrogen requirements would be met by the absorption of dietary aminoacids. Andrews also hypothesized that the midgut gland (MGG) was secreting enzymes for non-protein digestion that were contained within pigmented corpuscles we now know are endosymbiotic (cyano?)bacterial cells (identified as C and K corpuscles). These pigmented bodies reproduce within the acinar MGG cells and are freed in large quantities to the gastric vestibule. Adult female P. canaliculata were exposed to a high-protein diet for a 2 days acclimation period and then protease electrophoretic motility, molecular weight and activity were estimated simultaneously by a zymographic technique (PAGE without reductor agents and copolymerized with gelatin at 0.1%). A 130KDa protease was found in salivary gland (SG) tissue and in the crop sac content, while a 32KDa protease was found in the stomach content and MGG tissue, as well as in isolated C and K corpuscles. We conclude that the 130KDa protease originates in the SG, while the 32KDa protease appears to originate in the MGG’s endosymbionts.