title: The rapid development of the glucose transport system in the excysted metacestode of Hymenolepis diminuta.
abstract: Temporal changes in glucose transport capacity in excysted scoleces of Hymenolepis diminuta were examined. Assays involved incubation for 1 min in [3H]glucose after pre-incubation for 1 min to 8 h in saline. There were two abrupt increases in uptake velocity, a relatively small one between 15 and 75 min, and a large one between 5 and 6 h, during which the Vmax increased from 0.36 to 2.49 nmol/25 larvae/h. The second increase was unaffected when the pre-incubation saline contained 5 mM glucose, but it was completely blocked when the excysted larvae were pre-incubated in Ca(2+)-free saline. Abrupt glucose transport changes did not occur in intact cysticercoids or in scoleces when the substrate was [3H]leucine or [3H]uracil. Arrhenius plots (log V versus 1/temperature, 10-42 degrees C) were linear for intact cysticercoids, but were biphasic for both scoleces and adults with discontinuities at 20 +/- 1 degrees C. Thus, 'activation' of the excysted scolex seemed to involve a specific, Ca(2+)-dependent increase in number of glucose transporters functioning in the worm surface. The Arrhenius plots indicated that development in the final host does not involve a major change in lipid composition of the parasite's membranes.
authors.affiliation: Department of Biology, Berea College, Kentucky 40404.
authors.forename: R
authors.initials: R
authors.lastname: Rosen
authors.forename: M L
authors.initials: ML
authors.lastname: San
authors.forename: M E
authors.initials: ME
authors.lastname: Denton
authors.forename: J M
authors.initials: JM
authors.lastname: Wolfe
authors.forename: G L
authors.initials: GL
authors.lastname: Uglem
mesh_terms: D000818:Animals; D001693:Biological Transport, Active; D004058:Diffusion; D005947:Glucose / Q000378:metabolism*; D006926:Hymenolepis / Q000378:metabolism*; D013696:Temperature
chemical_list: D005947:Glucose