Organisation and sequence analysis of nuclear-encoded 5 s ribosomal RNA genes in cryptomonad algae

Abstract

Southern hybridisation, polymerase chain reaction (PCR), and nucleotide sequence, data indicate that the 5 s ribosomal RNA (rRNA) gene is linked to the main rRNA gene repeat in the nuclear genome of four cryptomonad algae (Rhinomonas pauca, Storeatula major, Komma caudata, and isolate cs 134). The 5 s gene is apparently transcribed in the same direction as the large and small subunit rRNA genes. The intergenic spacer between the 5 s gene and the large subunit rRNA gene exhibits length and sequence polymorphism among the different species. Cryptomonads contain two different eukaryotic genomes: the host nucleus and the nucleus of a eukaryotic endosymbiont. Mapping experiments with isolated chr..