Volume 68, Issue 4
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645


The mechanism of switching to sexual differentiation (gametocytogenesis) of appears to be controlled by stochastic mechanisms that are sensitive to environmental conditions. In any given conditions, only a proportion of genetically identical parasites will become committed to sexual development. We used an experimental co-culture system to detect the presence of diffusible molecules from asexually replicating bloodstream stages of that were capable of influencing the growth and differentiation of the parasite. We cultured two populations of in a shared environment separated by a membrane that allowed free diffusion of molecules. The data presented show that parasites in culture stimulate their own growth and replication, and constitutively inhibit sexual conversion via diffusible molecules. These observations support the model that for , the sexual pathway of development is the default, and that constitutive repression of the sexual pathway permits asexual multiplication to occur in the bloodstream of the human host.


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  • Received : 11 Mar 2002
  • Accepted : 03 Jan 2003

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