CHARACTERIZATION OF THE DP (II,I) DUPLICATION IN ASPERGILLUS-NIDULANS - PRESENCE OF THE ACR-A1 GENE AND ITS REGULATORY TRANSCRIPTION SEQUENCE IN THE TRANSPOSED SEGMENT

Segregation of w and Acr markers was demonstrated in self-crossed strains of Aspergillus nidulans that possess the Dp (II,I) duplication, and sensitivity to acriflavin. Segregation of gene w confirms heterozygosity of this gene in strains that bear w+ on chromosome I (duplication) and w on chromosome II. On the other hand, the segregation of gene Acr suggests the presence of this gene in the Dp (II,I) duplication, making the strains heterozygous for the Acr gene: Acr+ (chromosome II) and Acr (duplication, chromosome I). This result is only possible if a regulatory mutant sequence is present in the duplicated segment, repressing the expression of Acr, since Acr/Acr+ strain present an intermediate phenotype Acr+/-) between Acr+ (sensitive to acriflavin) and Acr (resistant to acriflavin) strains. This hypothesis was confined by the detection of Acr+ segregants in heterozygous and homozygous crosses for the Dp (II,I) duplication.