A histochemical study ofHaplosporidium malacobdellae, a balanosporidan endoparasite of the hoplonemerteanAmphiporus lactifloreus

Abstract

The distribution of 21 enzymes, including ten dehydrogenases, has been investigated in various life cycle stages ofHaplosporidium malacobdellae using specific histochemical techniques. Leucine naphthylamidase, alkaline phosphatase, arylsulphatase, and lipase are absent fromH. malacobdellae tissue. The distribution of various metabolites is also recorded.

Acid phosphatase, an enzyme involved in transmembranal phosphorylated transfer mechanisms, is present in high concentration in amoebulae, and juvenile plasmodial stages, which have been found in and around the host's blood vessels. The cytoplasmic concentration of periodic acid-Schiff (PAS) positive material increases as schizogony progresses.

α-glycerophosphate dehydrogenase activity decreases during the growth and multiplicative phases of parasite development, suggesting the presence of a glycolytic pathway in the later life cycle stages ofH. malacobdellae. During late schizogony/early sporogony stages the PAS-positive response diminishes and the activity of beta-galactosidase, beta-glucuronidase, and beta-glucosaminidase increases, possibly providing short-chain carbohydrate moieties which function as intermediary metabolites in the generation of chemical energy. Some enzymes normally associated with the glycolysis pathway and with the tricarboxylic acid cycle have been localized in the parasite tissues.

Catechol oxidase and peroxidase, which are known to be involved in the quinone tanning process of eggshell formation, have been visualized inH. malacobdellae tissue. The mature spore wall is suggested to be a quinone-tanned protein.