The avian malaria Plasmodium lophurae has a small number of heterogeneous ribosomal RNA genes.

The structure and number of the ribosomal RNA (rRNA) genes of the avian malaria parasite Plasmodium lophurae has been examined using Southern blot analysis and recombinant DNA techniques. The ribosomal DNA (rDNA) of P. lophurae has been cloned into the plasmid pBR322, beginning with size-selected populations of Cla I- and Hind III-restricted parasite DNA. The structure of two clones (CL-1 and HA-2) is presented in detail. These two clones together probably represent the entire 17s and 25s coding regions of P. lophurae. Analysis of quantitative genomic Southern blots reveals that there are approximately six rRNA genes per haploid genome, and that the rRNA genes may be divided into four distinct classes by restriction analysis. Examination of the flanking regions of these genes indicates that they are not organized into easily recognizable tandem repeats.