Abstract: Objective To explore the DNA typing of Trichophyton rubrum(T.rubrum)by Southern blotting,analyze the relationship between genotype and different geographical areas.Methods Forty nine strains of T.rubrum(21 from Nanjing,26 from Dalian and 2 from Beijing)were studied.DNA was extracted using cetyltrimethyl ammonium bromide(CTAB).The polymorphisms were detected by hybridization of EcoRⅠ-digested T.rubrum genomic DNA with a probe amplified from the small-subunit rDNA and adjacent internal transcribed spacer(ITS)regions.The probe was made using a pair of primers NS55'-AACTTAAAGGAATTGACGGAAG-3'3 and ITS45'-TCCTCCGCTTATTGATATGC-3'3 and was labeled by ³²P.The band patterns obtained by Southern blotting were used as the basis of the genotyping of T.rubrum.Results Twenty individual patterns(DNA type A to T) were recognized among 49 strains of T.rubrum.Type A to C accounted for 48.98% of all strains.The DNA patterns of Nanjing strains were represented by 3 bands,those of Dalian strains were represented by 4bands.Conclusion The DNA typing of T.rubrum using Southern blotting was sensitive,highly distinguishable.The DNA patterns of Nanjing strains are obviously diffe rent from those of Dalian strains.

Key words: Trichophyton, Genes,fungal, Mycological typing techniques