INSERTIONAL MUTAGENESIS OF DROSOPHILA HETEROCHROMATIN WITH SINGLE P-ELEMENTS

Insertional mutagenesis with transposable P elements has greatly facil itated the identification and analysis of genes located throughout the 70% of the Drosophila melanogaster genome classified as euchromatin. In contrast, genetically marked P elements have only rarely been shown to transpose into heterochromatin, By carrying out single P element i nsertional mutagenesis under conditions where position-effect variegat ion was suppressed, we efficiently generated strains containing insert ions at diverse sites within centromeric and Y-chromosome heterochroma tin. The tendency of P elements to transpose locally was shown to oper ate within heterochromatin, and it further enhanced the recovery of he terochromatic insertions. Three of the insertions disrupted vital gene s known to be present at low density in heterochromatin. Strains conta ining single P element insertions will greatly facilitate the structur al and functional analysis of this poorly understood genomic component .