Measuring the rates of transcriptional elongation in the female Drosophila melanogaster germ line by nuclear run-on

Abstract

We adapted the nuclear run-on method to measure changes in the rate of RNA polymerase II (pol II) transcription of repetitive elements and transposons in the female germ line of Drosophila melanogaster. Our data indicate that as little as an approximately 1.5-fold change in the rate of transcription can be detected by this method. Our nuclear run-on protocol likely measures changes in transcriptional elongation, because rates of transcription decline with time, consistent with a low rate of pol II re-initiation in the isolated nuclei. Surprisingly, we find that the retrotransposon gypsy and the repetitive sequence mst40 are silenced posttranscriptionally in fly ovaries.