The novel organization and complete sequence of the ribosomal RNA gene of Nosema bombycis

We present here for the first time the complete DNA sequence data (4301 bp) of the ribosomal RNA (rRNA) gene of the microsporidian type species, Nosema bombycis. Sequences for the large subunit gene (LSUrRNA: 2497 bp, GenBank Accession No. AY211393), the internal transcribed spacer (ITS: 179 bp, GenBank Accession No. AY211394), the small subunit gene (SSUrRNA: 1232 bp), intergenic spacer (IGS: 279 bp), and 5S region (114 bp) are also given, and the secondary structure of the large subunit is discussed. The organization of the N. bombycis rRNA gene is LSUrRNA-ITS-SSUrRNA-IGS-5S. This novel arrangement, in which the LSU is 5' of the SSU, is the reverse of the organizational sequence (i.e., SSU-ITS-LSU) found in all previously reported microsporidian rRNAs, including Nosema apis. This unique character in the type species may have taxonomic implications for the members of the genus Nosema. (C) 2003 Elsevier Inc. All rights reserved.