Incorporation of radioactive pyrimidine nucleosides into DNA and RNA of Eimeria tenella (Coccidia) cultured in vitro.

SYNOPSIS Autoradiographic methods were used to study the incorporation of tritiated cytidine, thymidine, and uridine into asexual stages of Eimeria tenella cultured in embryonic chick kidney cells. Developing parasites did not incorporate 3H-thymidine either when host cells were labeled prior to infection or when the cultures were labeled for 30 min, 48–72 hr after infection. Continuous exposure of infected cultures to 3H-thymidine for up to 18 hr resulted in light labeling of cell cytoplasm and schizonts. 3H-cytidine and 3H-uridine were incorporated into parasites developing in cultures that were labeled before infection. When the cultures were labeled for 30 min, 48–72 hr postinfection and fixed immediately, schizonts were labeled lightly with 3H-cytidine but contained dense accumulations of 3H-uridine.