Repeated DNA sequences in fungi

Several fungal species, representatives of all broad groups like basidiomycetes, ascomycetes and phycomycetes, were examined for the nature of repeated DNA sequences by DNA:DNA reassociation studies using hydroxyapatite chromatography. All of the fungal species tested contained 10-20% repeated DNA sequences. There are approximately 100-110 copies of repeated DNA sequences of approximately 4 x 10(7) daltons piece size of each. Repeated DNA sequence homoduplexes showed on average 5 degrees C difference of T(e)50 (temperature at which 50% duplexes dissociate) values from the corresponding homoduplexes of unfractionated whole DNA. It is suggested that a part of repetitive sequences in fungi constitutes mitochondrial DNA and a part of it constitutes nuclear DNA.