Cloning and characterisation of the rRNA genes from the human malaria parasite Plasmodium falciparum

Ribosomal DNA fragments from the human malaria parasite Plasmodium falciparum have been cloned and analysed in detail. Restriction mapping shows that the cloned fragments are different. However, they do have some similarities, in particular a small stretch of A+T-rich DNA located between the small and large subunit rRNA genes. A small rRNA gene has been mapped to this A+T-rich region. Copy number analysis reveals that each fragment is represented approximately 4 times in the genome, and implies that there are a total of 8 rRNA genes organised into at least two classes of transcription unit. Analysis of a third overlapping rDNA fragment indicates that the large subunit rRNA gene of at least one transcription unit contains an intervening sequence.