Studies on the aerobic and anaerobic metabolism of larval and adult Taenia taeniaeformis

Abstract

1. 1. The cysticercus larva of Taenia taeniaeformis raised in rats and mice differed in chemical composition and the rat larvae had a higher aerobic metabolic rate (rate of oxygen consumption, excretion of end products of aerobic fermentations). 2. 2. Adult tapeworms contained more protein, lipid, and tissue ash than the larvae, but less calcareous corpuscles. In the former the values for glycogen and total carbohydrates coincided closely, while in the cysticercus larva non-glycogen carbohydrates occurred in rather large amounts besides glycogen. 3. 3. Glucose in the medium raised the oxygen consumption of the larval Cysticercus only slightly in saline solutions, but the respiration of worms kept in serum was markedly higher than of those kept in salines. The rates of both aerobic and anaerobic gaseous exchanges were considerably higher in adult tapeworms than in their larvae. 4. 4. Aerobic and anaerobic incubation in sugar-free Tyrode's solution led in both adult and larval worms to rather large losses of dry substance, carbohydrate, and protein, but no lipids were utilized. In most series, some calcareous corpuscle material was used up. Large amounts of tissue ash disappeared from the bodies of only the adult worms under anaerobic conditions. 5. 5. The worms, both adult and larval, excreted lactic, pyruvic, acetic, and succinic acids, as well as ethanol and glycerol. Anaerobiosis decreased the production of pyruvic acid, but increased especially the production of succinic acid. Much greater amounts of succinate were produced by the adult worms than the larvae. This difference was more pronounced under aerobic than under anaerobic conditions. In serum the cysticercus larva eliminated considerably more ethanol than in sugar-free Tyrode's solution. The excretion of fumaric and malic acids was demonstrated only qualitatively; apparently the adult worms produce less malic acid than the larvae. 6. 6. Both larvae and adults excreted carbohydrates when incubated in sugar-free Tyrode's solution. The main sugar eliminated was identified as glucose, but at least two other unidentified sugars were excreted in smaller amounts. Anaerobically less carbohydrate was eliminated than in the presence of oxygen. In serum, on the other hand, the cysticercus larva assimilated sugar. 7. 7. Tentative carbon balances showed that not all the carbon of the metabolized carbohydrate was accounted for by the metabolites studied quantitatively; carbon dioxide of metabolic origin may well be the most important source of the missing carbon, but could not be studied quantitatively because of the overwhelmingly large carbon dioxide reserve represented by the calcareous corpuscles. 8. 8. It is pointed out that the differences between larval and adult Taenia taeniaeformis are essentially quantitative rather than qualitative.