FURTHER-STUDIES ON THE UPTAKE OF TRITIATED NUCLEIC-ACID PRECURSORS BY BABESIA SPP OF CATTLE AND MICE

Irvin A. D. and Young E. R. 1979. Further studies on the uptake of tritiated nucleic acid precursors by Babesia spp. of cattle and mice. International Journal for Parasitology 9: 109-114. An in vitro culture technique developed earlier was used to study the metabolism of nucleic acid precursors by Babesia microti and B. rodhaini of mice and by B. divergens and B. major of cattle. [3H]Hypoxanthine was readily incorporated by all species of parasite, and the presence of leucocytes did not affect this uptake. When parasites were maintained in culture their ability to incorporate [3H]hypoxanthine fell rapidly after 24 h, but when B. major was maintained at 4°C its subsequent ability to incorporate [3H]hypoxanthine persisted for at least 3 days. This finding could be of practical value in assessing infectivity of stored blood in vitro. On autoradiography, [3H]hypoxanthine appeared to be incorporated into both DNA and RNA of parasites. Salvage pathways for purine metabolism appeared to be important in all species of Babesia whereas for pyrimidine metabolism salvage pathways were more important for murine babesias and the de novo pathway more important for bovine species. This difference may relate to different permeabilities of bovine and murine erythrocyte membranes or may be a more fundamental species difference. © 1979.