Purine and pyrimidine transport in Schistosoma mansoni.

The uptake of purines and pyrimidines by adults of Schistosoma mansoni was studied. Cytosine, thymine, and uracil entered the worms entirely by diffusion. Adenine, guanine, hypoxanthine, and the nucleosides adenosine and uridine were absorbed in part by mediated systems. The results of inhibitor studies suggest the presence of 5 distinct transport sites for these latter compounds. The interaction of adenosine monophosphate with these sites was also studied.