The ribosomal RNA gene region of Nosema apis (Microspora): DNA sequence for small and large subunit rRNA genes and evidence of a large tandem repeat unit size.

The ribosomal RNA (rRNA) gene region of the microsporidium, Nosema apis, has been examined. A new method for extracting microsporidian genomic DNA from infected host tissue is described. Complete DNA sequence data are presented for the small subunit gene (1242 bp), the internal transcribed space (33 bp), and the large subunit gene (2481 bp to a putative termination point). This is the first time that the complete large subunit rRNA gene has been published for any microsporidian species. DNA sequence is also presented for the regions flanking the 5' end of the small subunit gene and the 3' end of the large subunit gene. The intergenic spacer is shown to be heterogeneous, showing variation in sequence and restriction sites rather than length and containing sequence repeats, which are a characteristic feature of intergenic spacers. The rRNA gene region of N. apis is shown to occur in a head-to-tail, tandemly repeated manner, as in other eukaryotes. This repeat unit is shown to be approximately 18 kb in length. The nucleotide sequence presented has been submitted to the Genbank database under the accession number U97150.