Differential gene expression in the ookinete stage of the malaria parasite Plasmodium berghei.

Plasmodium, the malaria parasite, undergoes a complex developmental program in its mosquito vector. The ookinete is the parasite form which invades the mosquito midgut and is an important stage for genetic mixing. To identify genes expressed during ookinete development and mosquito midgut invasion, purified zygotes and ookinetes of the rodent parasite Plasmodium berghei were used to construct a suppression subtractive hybridization cDNA library, enriched in sequences expressed in the ookinete stage.

Cryofracture electron microscopy of the ookinete pellicle of Plasmodium gallinaceum reveals the existence of novel pores in the alveolar membranes.

The malaria parasite invades the midgut tissue of its mosquito host as a motile form called the ookinete. We have examined the pellicle of the ookinete of Plasmodium gallinaceum by freeze-fracture and quick-freeze, deep-etch electron microscopy. The general organization is analogous to that of invasive stages of other members of Apicomplexa.

Sex ratio adjustment in Plasmodium gallinaceum.

The sex ratio of the avian malaria parasite, Plasmodium gallinaceum, was examined during the course of infection in its natural host, the chicken. Infections can have two possible outcomes: death of the host resulting from anaemia or self-cure and survival. In lethal infections the sex ratio remained female biased throughout, whereas in self-curing infections, the sex ratio became progressively less female biased.

Lipopolysaccharide-activated kinase, an essential component for the induction of the antimicrobial peptide genes in Drosophila melanogaster cells.

Eukaryotic organisms use a similar Rel/NF-kappaB signaling cascade for the induction of innate immune genes. In Drosophila, lipopolysaccharide (LPS) signal-induced activation of the Rel/NF-kappaB family transcription factors is an essential step in the transcriptional activation of inducible antimicrobial peptide genes. However, the mechanism by which the LPS-induced signaling pathway proceeds remains largely unknown.

Sex determination in malaria parasites.

A century ago, W. G. MacCallum identified distinct male and female forms in malaria parasites of both birds and humans.