[Advances in molecular biology of dermatophytes]

During the 44th meeting of The Japanese Society for Medical Mycology in Nagasaki, 2000, a forum was held entitled Advances in Molecular Biology of Dermatophytes. Based on the subject, target molecules and kind of approach, we selected seven presentations from over 100 of the poster abstracts. Six of them concerned identification and one concerned viability. Summaries of the 7 presentations are given in this article. Of presentations on the identification methods, 5 demonstrated their usefulness: 1) A sequence analysis of ITS 1 region in ribosomal DNA of several Microsporum species showed ITS 1 genospecies Arthroderma otae to be composed of A. otae, M. canis, M. equinum and M. audouinii. 2) RAPD may be useful for identifying isolates which are not clearly identifiable by conventional biological techniques. 3) Sequence analysis of CHS 1 was shown to be a rapid tool for species level identification of M. gypseum. 4) PCR-SSCP analysis was also useful for discrimination of dermatophytes with high reproducibility and sensitivity. 5) Strain identification of A. benhamiae isolates may be possible using RFLP analysis of NTS regions in ribosomal DNA. The other presentation concerning identification pointed out some important problems: RFLP of mitochondrial DNA and ITS sequencing of A. benhamiae showed that the results are sometimes in conflict with those obtained from biological techniques, or in some cases, between other molecular techniques. This implies that our concept of fungal species needs to be re-examined and perhaps amended. The presentation on viability introduced quantitative analysis of mRNA of ACT gene, a new application of a molecular technique. Since the mRNA expresses only in living cells, the method is highly useful as an indicator of fungal viability.