The roles of calcium and iron uptake in egg production by the digenetic trematodes, Echinostoma caproni and Schistosoma mansoni

Digenetic trematodes form a large group of medically important mammalian parasites. Production of eggs by digenes is required for continuation of the parasite lifecycle (transmission) and, for heterophyids, lung flukes and schistosomes, is an effector of host pathology. Although the pathway leading to egg production in digenes has been described, regulation of the process is not well understood. This work addresses whether iron and calcium, two ubiquitous regulatory agents in eukaryotes, are involved in the reproduction of digenetic trematodes.;The affect of supplemental iron on in vitro egg production of the intestinal parasite, Echinostoma caproni, was evaluated in a defined culture system. The results suggest that internal iron stores, not uptake of environmental iron, are used to sustain reproductive activity in culture. Methods for defining the role of iron uptake in trematode egg production are discussed.;The effect of pharmacological blockade of calcium influx on the in vitro production of eggs by Echinostoma caproni and Schistosoma mansoni was investigated. The results indicate that egg production by these digenes requires influx of calcium, and that this uptake can be inhibited by drugs that block mammalian calcium channels. This suggests that calcium channel blockers may provide a novel means of interrupting digene reproduction and consequent pathogenesis and transmission.