THE RIBOSOMAL-RNA GENES OF PLASMODIUM

This chapter focuses on the ribosomal RNA (rRNA) genes of plasmodium. The study of rRNA genes offers the biologist at least three possible research areas: (1) molecular biology, (2) molecular inference of phylogeny based upon molecular sequence data, and (3) rRNA-based specific detection of organisms, which can be used diagnostically. The members of the unicellular apicomplexan parasitic genus Plasmodium employ a dichotomous life style existing in association with an invertebrate (usually Anopheline) mosquito vector and a vertebrate host. The demonstration of the ability of the parasite to express different distinct rRNA genes at different points in its life cycle has a number of implications, which must be considered in the light of the circumstances of the life cycle. Ribosomes consist of a complex of the rRNA species already described and proteins. Two distinct subunits, the large and the small, associate around messenger RNA (mRNA) to form the active ribosome. The genus Plasmodium is contained within the phylum Apicomplexa, which is defined by the possession of all or part of a characteristic set of structures that together form what is termed “the apical complex.” Classical detection of microorganisms for medical diagnosis has relied upon culture of those organisms on defining media. The study of rRNA genes in Plasmodium has provided valuable information about the molecular biology, biology, and evolutionary history of members of the genus. © 1994, Academic Press Limited