Nucleotide structure of the Scytalidium hyalinum and Scytalidium dimidiatum 18S subunit ribosomal RNA gene: evidence for the insertion of a group IE intron in the rDNA gene of S. dimidiatum

Abstract

The molds Scytalidium dimidiatum ( Nattrassia mangiferae synanamorph) and Scytalidium hyalinum are responsible for dermatomycosis in humans. We sequenced their 18S subunit ribosomal RNA gene to identify these species with molecular biology-based methods. The coding sequences differed by a single polymorphism (A in S. dimidiatum, G in S. hyalinum). Moreover, we found an insert at position 1199 in the 18S rRNA gene sequence of S. dimidiatum. Its potential secondary structure was characteristic of a group IE intron. Bioinformatic and phylogenic group IE intron analyses generated four main homogeneous clusters. The S. dimidiatum intron is original and not related with other known IE group introns.