Independent characterization of thymidine transport and subsequent metabolism in Hymenolepis diminuta--I. Comparison of short- and long-term transport kinetics.
1. Initial transport kinetics of thymidine in the rat tapeworm, Hymenolepis diminuta have been characterized independently of subsequent metabolic activity, using short term (5s) incubation times. 2. Thymidine uptake by 10 day old worms using long-term (2 min) incubation times underrepresents actual transport capabilities by allowing subsequent phosphorylation to act as a rate limiting step in the coupled transport-metabolism pathway. 3. Apparent Kt values for 6 and 10 day old H. diminuta thymidine transport at 5s incubation times (0.073 nM and 0.091 mM) are close in value. Distinctions previously observed at 2 min incubation times may actually represent metabolic (and not transport) differences.
Insler
G D
GD
Department of Biology, Adelphi University, Garden City, NY 11530.
D000818:Animals; D001692:Biological Transport; D006926:Hymenolepis / Q000378:metabolism*; D007700:Kinetics; D010766:Phosphorylation; D013936:Thymidine / Q000378:metabolism*
D013936:Thymidine