Complete sequence and gene organization of the Nosema heliothidis ribosomal RNA gene region.

By sequencing the entire ribosomal RNA (rRNA) gene region of Nosema heliothidis isolated from cotton bollworm (Helicoverpa armigera), we showed that its gene organization is similar to the type species, Nosema bombycis: the 5'-large subunit rRNA (2,490 bp)-internal transcribed spacer (192 bp)-small subunit rRNA (1,232 bp)-intergenic spacer (274 bp)-5S rRNA (115 bp)-3'. We constructed two phylogenetic trees, analyzed phylogenetic relationships, examined rRNA organization of microsporidia, and compared the secondary structure of small subunit rRNA with closely related microsporidia. The latter two features may provide important information for the classification and phylogenetic analysis of microsporidia.