Changes in the chemical composition ofHymenolepis diminuta(Cestoda:Cyclophyllidea) during prepatent development within the rat intestine

Abstract

The changes in the percentage chemical composition of both complete strobilae, and of the immature, mature, and gravid regions of the strobila ofHymenolepis diminutahave been studied during development of the worms from 5 to 16 days postinfection. The chemical components that have been evaluated are non-protein nitrogen, protein nitrogen, ribonucleic acid, deoxyribonucleic acid,lyo-glycogen,desmo-glycogen and total lipid.While the nitrogen, RNA and DNA fractions, expressed asμg/mg of worm dry weight, all decreased markedly with increasing worm age and size, the carbohydrate and lipid fractions increased over the same period of development.In worms up to 7 days old there is a high non-protein nitrogen value, high RNA and DNA fractions, thelyo-glycogen component of the total carbohydrate is very large, but the amount of carbohydrate expressed as a percentage of dry weight is low. These values are associated with the very high rate of metabolism of the young worms. From 7 to 16 days postinfection the rate of growth slows considerably, which is reflected in the corresponding decreases in the non-protein nitrogen, RNA and DNA fractions, and the increase in the total carbohydrate percentage.The changes in the chemical composition along a complete strobila complement the morphological evidence as the emphasis switches from segmentation to tissue differentiation and organ maturation.The changes with age in the percentage composition of the same region of the strobila show that neither the complete worms nor the different regions of a strobila are static in terms of their chemical components, but are changing systems which may be correlated with the ontogenetic development and migrational behaviour of the worms.