Isolation, Characterization and Synthesis of DNA from a Malaria Parasite*

SYNOPSIS. Methods for the isolation and purification of DNA from the intraerythrocytic stages of the avian malaria parasite Plasmodium lophurae are described. The DNA of P. lophurae was found to have a 19 mole‐percent guanine plus cytosine (G+C) composition as determined by melting temperature and density measurements in CsCl gradients, whereas that of the host cell nucleus was 35 molepercent G+C. Synthesis of DNA by P. lophurae was studied by following the incorporation of P 32 during the in vitro growth of plasmodia in infected cell suspension cultures. DNA synthesis was linear during the multiple nuclear divisions of a single growth cycle in highly synchronous cultures. Separation of P 32 labeled parasite DNA from the DNA of the duck erythrocyte on CsCl gradients showed that only parasite DNA was synthesized.