The malaria parasite has an intrinsic clock

Plasmodium 's inner clock Malarial fevers are notably regular, occurring when parasitized red blood cells rupture synchronously to release replicated parasites. It has long been speculated that the Plasmodium 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 of P. falciparum in vitro and in the mouse model of P. chabaudi malaria. Smith et al. discovered that four strains of P. falciparum have circadian and cell cycle oscillators, each with distinctive periodicities that can be experimentally manipulated. Rijo-Ferreira et al. found that gene expression in P. 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