UNIQUE AMANITIN RESISTANCE OF RNA-SYNTHESIS IN ISOLATED-NUCLEI FROM AMANITA SPECIES ACCUMULATING AMANITINS

In order to understand the basis upon which amanitin-accumulating species of Amanita are able to develope in the presence of these specific inhibitors of RNA synthesis, the in vitro RNA synthesizing activities of nuclei isolated from amanitin-accumulating species Amanita hygroscopica (culture, derived from amanitin-accumulating carpophore) and A. suballiacea (carpophore), and from the non-accumulating species A. solitaria (culture) and A. brunnescens (carpophore) were tested for their sensitivities to α-amanitin inhibition. The nuclear RNA synthesizing activities obtained from both carpophores and cultures of non-accumulating organisms displayed significant sensitivities to α-amanitin, whereas those obtained from accumulating organisms displayed remarkable resistance to α-amanitin. The observed relationship between levels of amanitins in carpophores and resistance of the RNA synthesizing activities to inhibition by α-amanitin supports the hypothesis that amanitins may function as regulators of mRNA transcription in Amanita species. © 1979 Springer-Verlag.