STAGE-SPECIFIC EXPRESSION OF PROLIFERATING CELL NUCLEAR ANTIGEN AND DNA-POLYMERASE-DELTA FROM PLASMODIUM-FALCIPARUM

Antisera raised against proliferating cell nuclear antigen (PfPCNA) an d DNA polymerase delta (PfDNA Pol delta) have been used against extrac ts from synchronised parasites to show that both proteins accumulate i n trophozoites and persist in schizonts. The steady-state transcripts from both PfPCNA and PfDNA Pol delta also accumulate at the trophozoit e stage. However, nuclear run on analysis shows that, whereas PfDNA Po l delta promoter activity is absent in rings but present in trophozoit es and schizonts, the PfPCNA promoter is active throughout the intraer ythrocytic cycle. This suggests that mechanisms regulating the express ion of these two genes may be different although their coordinated act ivity is required for DNA replication.