The Plasmodium lophurae (Avian Malaria) Ribosome*

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Abstract
Ribosomes were isolated from P. lophurae [maintained in ducks] by Triton X-100 lysis and ultracentrifugation. P. lophurae ribosomal subparticles, produced by treatment of ribosomes with puromycin, were separated by sucrose gradient centrifugation. The nucleotide base composition of P. lophurae ribosomal RNA (rRNA) from intact ribosomes and subparticles was low in guanine-cytosine (G + C) content (.apprx. 37%) whereas the rRNA of the host cell (duck reticulocyte) was considerably higher (64%). The rRNA of the malaria parasite was typically protozoan, with sedimentation values of 25S and 17S. In vitro, free parasites and malaria-infected red cells incorporated radioactive adenosine into large and small plasmodial subparticles; label was recovered in the 25S and 17S RNA. Host ribosomes probably do not contribute to ribosome biogenesis in this malaria, rather parasite rRNA is the transcription product of plasmodial cistrons.