Leishmania donovani: characteristics of adenosine and inosine transporters in promastigotes of two different strains |
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Authors: | P O Ogbunude M H al-Jaser H P Baer |
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Institution: | Department of Biological and Medical Research, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia. |
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Abstract: | The nucleoside transport characteristics of two strains of Leishmania donovani promastigotes were studied. Strain S1, growing in fully defined medium, and strain S2 (MHOM/ET/67/HA3) both transported adenosine and inosine, but only strain S1 transported uridine and thymidine. Competition studies in the presence of 100 microM of unlabeled adenosine, inosine, guanosine, 2'-deoxyadenosine, tubercidin, formycin B, 3'-deoxyinosine as well as uridine, thymidine and cytidine, with either 1 microM 3H]adenosine or 3H]inosine as permeant, were carried out. The inhibition profile with 3H]inosine as permeant was essentially identical in S1 and S2 promastigotes, indicating that the same inosine transporter was present in both strains. However, with 3H] adenosine as permeant, significant differences were noted between the two strains. Thus, only adenosine, 2'-deoxyadenosine, tubercidin, uridine, and thymidine were strongly inhibitory in S1 promastigotes, while essentially all nucleosides tested were effective in S2 promastigotes. This indicates that adenosine transport in S2 promastigotes seems to involve a transporter differing from that described for S1 promastigotes. |
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