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.

Kinetics of proglottid formation, maturation and shedding during development of Hymenolepis nana

“…This tendency becomes more and more prominent as the stages of maturation proceed. An analysis of comparable data from other published works (Roberts, 1961;Mettrick & Cannon, 1970) showed that the same is true for H. diminuta. The cause of this decrease in maturation rate is unclear.…”

“…The cause of this decrease in maturation rate is unclear. Possible factors affecting the maturation rate include the changes in biochemical composition in proglottids that are even of comparable stages of maturation (Mettrick & Cannon, 1970), the difference in micro-environment along the length of the worm as suggested by the migration of worms in the intestine (Hopkins & Allen, 1979) and the changes in the activity of the rostellar gland cells (Davey & Breckenridge, 1967). The remarkable increase in size of the proglottid during the early development might also affect the maturation rate.…”

Changes in the distribution of Hymenolepis diminuta (Cestoda: Cyclophyllidea) within the rat intestine during prepatent development

“…Biochemical analysis of the worms during the prepatent period has in fact confirmed that there are marked changes in the chemical composition of H. diminuta associated with the migrational movements of the worm (Mettrick and Cannon 1970).…”

Calorific Values in the Phylum Platyhelminthes: The Relationship Between Potential Energy, Mode of Life and the Evolution of Entoparasitism

“…diimnuta gravid proglottids contain a higher proportion of lipid than do immature and mature ones (Fairbairn, Wertheim, Harpur and Schiller, 1961 ;Mettrick and Cannon, 1970) and this is reflected in their high calorific value (Table II). If the cestode strobila is viewed as a series of progressively maturing reproductive units, though, rather than as a single individual, it becomes legitimate to compare only the immature and mature proglottids with the whole individuals from other flatworm groups.…”