Schistosoma mansoni Proteases Sm31 (Cathepsin B) and Sm32 (Legumain) Are Expressed in the Cecum and Protonephridia of Cercariae

• Published in: The Journal of parasitology Vol. 87; no. 5; pp. 1218 - 1221
• Main Authors: Skelly, P. J, Shoemaker, C. B
• Format: Journal Article
• Language: English
• Published: Lawrence, KS American Society of Parasitologists 01.10.2001; Allen Press Inc
• Subjects: Amino acids; Animals; Antibodies; Antibodies, Protozoan - chemistry; Antigens, Helminth; Biochemistry. Physiology. Immunology. Molecular biology; Biological and medical sciences; Blotting, Western; Cathepsin B; Cecum; Cecum - enzymology; Cercaria; Cercariae; Confocal microscopy; Cysteine Endopeptidases - biosynthesis; Cysteine Endopeptidases - genetics; DNA, Protozoan - genetics; Enzymes; Erythrocytes; Escherichia coli - genetics; Female; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Developmental; Gene Expression Regulation, Enzymologic; Helminth Proteins - biosynthesis; Helminth Proteins - genetics; Hemoglobin; Hemoglobins; Immunohistochemistry; Invertebrates; Legumain; Life cycles; Localization; Male; Mice; Mice, Inbred C57BL; Microscopy; Microscopy, Confocal; Nemathelminthia. Plathelmintha; Osmoregulation; Parasite hosts; Parasites; Parasitology; Physiology. Development; Plant Proteins; Polymerase Chain Reaction; Proteins; Recombinant Proteins - biosynthesis; Recombinant Proteins - genetics; RESEARCH NOTES; Schistosoma mansoni; Schistosoma mansoni - enzymology; Schistosoma mansoni - genetics; Schistosoma mansoni - growth & development; Snails - parasitology; Vertebrates; Western blotting; Worms; United States > US; California; Schistosoma mansoni; Enzyme; Cysteine endopeptidases; Cecum; Gut; Plathelmintha; Parasite; Protonephridium; Trematoda; Cercaria; Peptidases; Legumain; Helmintha; Cathepsin B; Hydrolases; Invertebrata
• ISSN: 0022-3395; 1937-2345
• DOI: 10.1645/0022-3395(2001)087[1218:SMPSCB]2.0.CO;2

Adult Schistosoma mansoni parasites live in the bloodstream of their vertebrate hosts where they consume red blood cells. Hemoglobin, released from the ingested red blood cells, is degraded by a variety of parasite proteases, including Sm31 (cathepsin B) and Sm32 (schistosome legumain). In this study the localization pattern of the Sm31 and Sm32 enzymes in cercariae (the infectious life cycle stage) was examined. Antibodies generated against recombinant Sm31 and Sm32 recognize their respective proteins in Western blots of soluble parasite extracts. Highest levels are seen in adult female extracts, whereas the level of both proteins is below detection in cercarial extracts. However, in fixed, whole cercariae, both proteins are seen in the cecum and protonephridia. In the cecum, the staining pattern has a granular appearance, suggesting that the proteins are packaged in vesicles. In the protonephridial system, Sm31 and Sm32 are detected in all 8 flame cells in the cercarial body and in both flame cells in the cercarial tail. The distribution of the 2 proteins differs in the flame cells. Examination of immunostained cercariae using laser scanning confocal microscopy shows that whereas Sm31 is located in the tubule cell, Sm32 is found in both the tubule cell and its adjoining cap cell. These findings suggest that the proteins are involved in the proposed excretory and osmoregulatory roles of flame cells.