Related Experiment Videos
Mechanism of 3-0-methylglucose uptake by Hymenolepis diminuta
1School of Biological Sciences, University of Kentucky, Lexington 40506.
Abstract:
The mechanism by which Hymenolepis diminuta (Cestoda) absorbs 3-0-methylglucose (30MG) in vitro was analyzed. Influxes of 0.1 and 0.01 mM-3H-30MG during incubations ranging from 5 s to 60 min were not affected significantly when 10 mM-unlabeled 30MG was present as an inhibitor. After 60 min in 0.1 mM-3H-30MG, the concentration of labeled substrate within tapeworms (0.04 mumol ml-1 worm water = 0.04 mM) was less than that of the bathing medium. Tapeworms incubated for 1 h with either 5 mM-glucose or 5 mM-beta-methylglucose (beta MG) gained 15-20% more water than did tapeworms in saline alone, but addition of 5 mM-30MG to the saline had no significant effect on weight change. When the 3H-30MG concentration was varied from 0.01 to 10 mM, influxes were a linear function of substrate concentrations. These analyses show that H. diminuta absorbs 30MG by simple diffusion alone. Thus, use of this monosaccharide to estimate the internal concentration of actively transported sugars (e.g. glucose or beta MG) in H. diminuta is invalid.
Insights
Hymenolepis diminuta absorbs 3-O-methylglucose (30MG) solely through simple diffusion, not active transport. This finding indicates that 30MG cannot be used to accurately measure actively transported sugars like glucose in this tapeworm.
Area of Science:
- Parasitology
- Biochemistry
- Molecular Transport
Background:
- Hymenolepis diminuta is a tapeworm parasite.
- Understanding nutrient absorption mechanisms in parasites is crucial for developing control strategies.
Purpose of the Study:
- To investigate the absorption mechanism of 3-O-methylglucose (30MG) in Hymenolepis diminuta.
- To determine if 30MG is absorbed via active transport or simple diffusion.
Main Methods:
- In vitro analysis of 3H-30MG influxes at varying concentrations and incubation times.
- Assessing the effect of unlabeled 30MG as an inhibitor.
- Measuring tapeworm water content changes in response to different sugars.
Main Results:
- 3H-30MG influx was not inhibited by unlabeled 30MG.
- 3H-30MG concentration in tapeworms remained lower than the bathing medium.
- 3H-30MG influx showed a linear relationship with substrate concentration.
- Glucose and beta-methylglucose (beta MG) induced water uptake, unlike 30MG.
Conclusions:
- Hymenolepis diminuta absorbs 3-O-methylglucose exclusively via simple diffusion.
- 3-O-methylglucose is not a reliable marker for estimating internal concentrations of actively transported sugars like glucose or beta MG in this parasite.