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The structural organization of the rRNA genes in Borrelia burgdorferi was determined. Hybridization studies showed that the rrl and rrf sequences are closely associated, while the rrs sequence is distantly located from either of the former rRNA genes. The rRNA gene organization of B. burgdorferi is different from that in other spirochaetes. Comparisons based on rRNA genes showed that B. burgdorferi exhibits similar organization as Thermus thermophilus and Pirellula marina.

The partial 16s ribosomal RNAsequences of five aerococcus-like organisms (ALO) isolated from urinary tract infection patients were investigated to determine their phylogenetic position. Reverse transcriptase analysis of ALO ribosomal RNA revealed a distinction fromAerococcus viridian. The ALOs have 74 base and phenotype differences from that of A. viridian. The results indicate a need for the ALOs from the isolate to benamed Aerococcus urinae. The new species is proposed to be classified under thegenus Aerococcus.

The small subunit (18S) ribosomal RNA sequence of Blastomyces dermatitidis was analyzed and compared to those of fourteen other eukaryotic organisms. B. dermatitidis was found to be similar to that of Ascomycetes Neurospora crassa and Podospora anserina. The nucleotide sequence of the small subunit ribosomal RNA was identical to that of phase-specific cDNA clones derived by reverse transcription of RNA isolated from yeast and mycelial phases of B. dermatitidis Both the genomic and RNA level at position 1352 exhibited heterogeneity.

Different strains of Salmonella were examined for cleavage patterns of their 23S ribosomal RNA (rRNA). Most of the strains examined contained fragmented 23S rRNA, the patterns of which were highly variable. The sizes of these subfragments ranged from 13S to 21S. Thirty strains of a closely related species, Escherichia coli, contained no fragmented rRNA. However, all strains of Brucella and Agrobacterium examined had the same pattern of fragmented 23S rRNA. The post-transcriptional processing of 23S rRNA appears to be polyphyletic and confers a selective advantage.