Transcriptional patterns in the X chromosome of Sciara coprophila following exposure to magnetic fields.

We previously demonstrated that exposure of salivary gland cells of the dipteran, Sciara coprophila, to either asymmetrical or symmetrical changing magnetic fields results in an increase in the incorporation of radioactive uridine into RNA. The present report is an analysis of the grain count distribution over the X chromosome of Sciara in transcription autoradiograms following exposure of the salivary gland cells to two pulsed magnetic signals and a 72-Hz sine wave signal. The results show augmented uptake of 3H-uridine into nascent RNA chains following short exposures of the cells to magnetic fields. Transcription is augmented in previously active loci, as well as at chromosome regions that are not detectable as active in control cells. The quantitative pattern of RNA synthesis in transcription autoradiograms is hypothesized to be signal specific on the basis of differences in grain counts over significantly labelled chromosome sites.