Incorporation of calcium into the soft tissues and calcareous corpuscles of larval Taenia taeniaeformis

Summary

Larval Taenia taeniaeformis in vivo accumulates ⁴⁵Ca²⁺ in soft tissues and calcareous corpuscles. Radioactivity was demonstrable in the corpuscles six months after a single dose of ⁴⁵Ca²⁺ was administered to the host by means of a stomach tube. Ca²⁺ also was taken up by isolated larvae. Accumulation in vitro was more rapid than in vivo and was correlated with the external Ca²⁺ concentration. Temperature variation, oxygen availability, and metabolic inhibitors had little effect on the Ca²⁺ uptake, indicating that active transport of Ca²⁺ is unlikely in this parasite. Variations in the external P_i concentrations had no effect on Ca²⁺ accumulation or on its distribution. Addition of 5% CO₂ increased the uptake of Ca²⁺ by the calcareous corpuscles under anaerobic conditions. Radioactivity from NaH¹⁴CO₃ also was accumulated in soft tissues and corpuscles of T. taeniaeformis. Assuming that the ¹⁴C taken up by the corpuscles was in the form of ¹⁴CO ²⁻₃ , the ratio of Ca²⁺ to CO ²⁻₃ accumulation in the corpuscles approximates the ratio of these constituents in dolomite: CaMg(CO₃)₂.