Frequency and Diversity of RNA Sequences in Different Cell Types of the Fungus Schizophyllum commune

Abstract

In the basidiomycete S. commune an RNA complexity of 13,500 average-sized (1100 nucleotides) RNA sequences was found by means of RNA excess hybridization to complementary [c] DNA. A total of 600 abundant poly(A)-containing RNA sequences were present in about 100 copies/cell, whereas the rare 13,000 poly(A)-containing RNA sequences were present in about 5 copies/cell on average. Homologous and heterologous cDNA hybridizations to poly(A)-rich RNA revealed some quantitative but no significant qualitative differences between the monokaryotic and the dikaryotic cell type. Heterologous hybridization and subsequent hybridizations of remaining single-stranded cDNA to poly(A)-rich RNA from both cell types showed qualitative differences amounting to 2-3% of the rare sequences in the 2 cell types. From the results of similar hybridizations with total RNA, i.e., including non-polyadenylated RNA, it could be calculated that the RNA sequences in monokaryons and dikaryons are at least 99% the same. Identity of RNA sequences in monokaryons and dikaryons was also inferred by comparison of the patterns of polypeptides synthesized by translation of total RNA in cell-free systems.