A study of selected Plasmodium yoelii messenger RNAs during hepatocyte infection

We investigated the expression of several mRNAs in exoerythrocytic and eryt hrocytic stages of Plasmodium yoelii in infected mice, focusing our attenti on on genes thought to be involved in signal transduction (like pypka and p ymap-1, encoding homologues of cAMP-dependent and mitogen-activated protein kinases, respectively) and cell cycle progression (those encoding the cdc2 -related kinases Pycrk-1, Pycrk-3 and Pymrk). Messengers coding for-enzymes involved in general processes such as DNA replication and RNA transcriptio n (both subunits of the ribonucleotide reductase (Pymr1, Pyrnr2) and RNA po lymerase II) as well as a messenger coding for Pys21, a sexual stage-specif ic protein, were also investigated. Total RNA was prepared from livers of i nfected mice at different times post sporozoite inoculation. In contrast to the pys21 transcript, which was observed only in infected erythrocytes, al l messenger species could be detected in the liver by RT-PCR, peaking at 43 h post infection, a time when parasite burden was maximum, and decreasing markedly thereafter to become hardly visible at 168 h. Some transcripts (py pka, pymap-1, pymr1 and pyrnr2) could be detected 12 h after infection, whi le others (pymrk and pyrnapolII) did not become detectable until 24 h. In a ddition, we characterised all these messengers by Northern blot of total RN As extracted from infected erythrocytes. Taken together, these data suggest that a similar set of regulatory genes is expressed during both exoerythro cytic and erythrocytic schizogony. (C) 2000 Elsevier Science B.V. All right s reserved.