On the regulation of gene expression: incompatibility in schizophyllum.

A new functional class of nucleic acids is postulated on the basis of the multiallelic incompatibility system regulating sexual morphogenesis in the higher fungi. A physical-chemical basis for distinguishing molecules active, as opposed to inactive, in promoting morphogenesis is established by the secondary structure of the resultant nucleic acid duplexes. This regulatory mechanism may be of broad import.