Evidence for Position-Effect Suppression of the Ribosomal RNA Cistrons in <i>Drosophila melanogaster</i>

Abstract

Unambiguous evidence is presented that two X-chromosome inversions produce lethality in X/O males because of position-effect suppression of genes in the basal heterochromatin. The data support the hypothesis that the ribosomal RNA cistrons are the genes suppressed. There is evidence for a region in the X basal heterochromatin that may act as a regulator of rDNA activity.