title: Haematoloechus medioplexus: light and electron microscope localization of dipeptidyl aminopeptidases I and II in the gastrodermis.
abstract: The exopeptidases, dipeptidyl aminopeptidases I and II (EC 3.4.14.1 and EC 3.4.14.2, respectively) were demonstrated cytochemically at light and electron microscope levels in the gastrodermis of adult Haematoloechus medioplexus recovered from the lungs of naturally infected Rana pipiens. Lys-Ala-4-methoxy-beta-naphthylamide and Pro-Arg-4-methoxy-beta-naphthylamide were used as specific substrates. Reaction products from both enzymes were observed in the gastrodermis in what are believed to be vesicles analogous to secondary lysosomes. The localization of the enzymes in these vesicles coincides with previous reports of the distribution of acid phosphatase and esterase activities. The hydrolases are believed to function both intracellularly by autophagy and extracellularly by digestion of host globin in the cecal lumen. Cathepsin B activity was not observed following the cytochemical protocol used in this investigation.
mesh_terms: D000818:Animals; D020789:Cathepsin C; D004064:Digestive System / Q000201:enzymology* / Q000648:ultrastructure; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000378:metabolism* / Q000502:physiology; D010450:Endopeptidases / Q000378:metabolism*; D008854:Microscopy, Electron; D011894:Rana pipiens / Q000469:parasitology; D014200:Trematoda / Q000201:enzymology* / Q000648:ultrastructure
chemical_list: D010450:Endopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D020789:Cathepsin C; C100151:dipeptidyl peptidase II