The malaria parasite has an intrinsic clock

Plasmodium 's inner clockMalarial fevers are notably regular, occurring when parasitized red blood cells rupture synchronously to release replicated parasites. It has long been speculated that thePlasmodium parasites that cause malaria must therefore have intrinsic circadian clocks to be able to synchronize like this. Two groups have now probed gene expression in experiments and models using data obtained during the developmental cycles ofP. falciparum in vitro and in the mouse model ofP. chabaudi malaria. Smithet al. discovered that four strains ofP. falciparum have circadian and cell cycle oscillators, each with distinctive periodicities that can be experimentally manipulated. Rijo-Ferreiraet al. found that gene expression inP. chabaudi was strikingly rhythmic, persisted during constant darkness and in infections of arrhythmic mice, and synchronized by entraining to the host's periodicity.Science , this issue p.754 , p.746