Electrophoretic karyotype of Dipodascus (Endomyces) magnusii: two main intraspecific chromosomal polymorphisms associated with the difference in total genome size

Abstract

This study describes the karyotype of strain 270 of the yeast-like fungus Endomyces magnusii. It consists of 13 chromosomal DNA molecules, the size of which range between 1.2 and 5.7Mb producing a genome size of approximately 38Mb. By comparing the karyotype of six strains of E. magnusii, we revealed two main chromosome length polymorphisms (CLPs) associated with a pronounced difference in the total genome size (roughly 50%). Karyotype heterogeneity between two main CLPs was demonstrated by Southern analysis with three heterologous probes. The same species affiliation of six E. magnusii strains was confirmed by morphological and cytological studies, protein fingerprint comparisons, as well as restriction analysis of mitochondrial DNA and genomic Southern analysis.

Development of a transformation system for the multinuclear yeastDipodascus (Endomyces) magnusii

“…DNA sequencing of both ends of the fragment revealed sequences homologous to 18S and 25S rRNA genes, respectively. Hybridization of a radioactively labelled DNA probe derived from this 4·5 kb DNA fragment detected the same chromosome bands (Figure 2) as an heterologous rDNA probe used previously (Filipp et al, 1995). Hybridization of the 4·5 kb probe with EcoRI-digested genomic DNA identified three bands (1·2, 3·3 and 4·5 kb) which may represent polymorphism in the restriction sites of the rDNA repeats (not shown).…”

“…Southern blotting, DNA hybridization, DNA cloning and E. coli transformation were performed essentially as described in Sambrook et al (1989). Conditions for separating the chromosomal DNA by pulsed field gel electrophoresis were the same as described previously (Filipp et al, 1995). DNA was sequenced on double-stranded plasmid templates by a dideoxy chain-termination method using [ 35 S]dATP (Amersham) and the T7 sequencing kit (Pharmacia).…”

“…Our laboratory characterized and cloned D. magnusii mitochondrial DNA and uncovered the virus-like particles containing dsRNA molecules . Recently, an electrophoretic karyotype of D. magnusii has been described (Filipp et al, 1995).…”

Concerted Evolution in the Ribosomal RNA Genes of an Epichloë Endophyte Hybrid: Comparison between Tandemly Arranged rDNA and Dispersed 5S rrn Genes

“…This was unexpected, as the majority of fungi examined have a single array, although multiple arrays have been reported previously (e.g., Viaud et al, 1996;Filipp et al, 1995). Technical difficulties associated with determining rDNA locus number mean that the situation is not known for most fungi, and it remains to be seen how general the presence of multiple rDNA loci is.…”