Temporal relationships on macromolecular synthesis during the asexual cell cycle of Plasmodium falciparum

Abstract

The over-all synthesis of DNA, RNA and protein was studied during the asexual cell cycle of Plasmodium falciparum. A method for stringent synchronization of the culture was developed. Rates of synthesis of the three macromolecules were determined every four hours by labelling the parasites with radioactive precursors during 30 min pulses. There was a peak of synthesis of DNA at 44 hours. Between 33 and 45 hours the rate of synthesis of DNA was exponential. Maximum RNA synthesis was reached at 36 hours. For proteins there were two peaks, one at 24 and the other at 40 hours. Partial degradation of the RNA synthesized by schizonts was detected.

The 'permeome' of the malaria parasite: an overview of the membrane transport proteins of Plasmodium falciparum

“…In this study we measured the total RNA content of malaria parasites as they progressed through the intraerythrocytic lifecycle and found there to be around 160 times more RNA in late trophozoites/schizonts (around 40 hours old) than in young ring-stage parasites (around 4 hours old) (Figure 3). This is in agreement with previous findings of a considerably elevated rate of transcription in trophozoites compared with ring-stage parasites [92,93]. …”

Extrachromosomal DNA in the Apicomplexa

“…It has been known for many years that bulk DNA synthesis starts in blood stage culture in late trophozoites (47,57,91,99), not long before the onset of the nuclear divisions that mark the start of schizogony. It is now known that both mtDNA and nuclear DNA start replicating together (87,99).…”

A Cluster of Ring Stage–specific Genes Linked to a Locus Implicated in Cytoadherence inPlasmodium falciparumCodes for PEXEL-negative and PEXEL-positive Proteins Exported into the Host Cell

“…The ring stage lasts for almost half of this cycle (ϳ0-20 h after invasion) and shows low metabolic activity with little change in size and morphology (Zolg et al, 1984;de Rojas and Wasserman, 1985). P. falciparum ring forms are the only stages apparent in the blood circulation of infected humans, because more mature parasites adhere to the endothelium of various organs to avoid clearance by the spleen (Langreth and Peterson, 1985).…”

“…The symptoms of this disease are associated with the continuous asexual multiplication of P. falciparum parasites within red blood cells (RBCs) (for review, see Miller et al, 2002). In this part of the life cycle, the parasite develops, within 48 h from the ring stage, to the trophozoite stage and finally to the schizont stage after which the infected RBCs (IRBCs) rupture, releasing up to 32 merozoite stage parasites that infect new RBCs.The ring stage lasts for almost half of this cycle (ϳ0-20 h after invasion) and shows low metabolic activity with little change in size and morphology (Zolg et al, 1984;de Rojas and Wasserman, 1985). P. falciparum ring forms are the only stages apparent in the blood circulation of infected humans, because more mature parasites adhere to the endothelium of various organs to avoid clearance by the spleen (Langreth and Peterson, 1985).…”