Abstract

Cracks in the one‐gene, one‐band paradigm for polytene chromosome organization are widening. At the same time evidence is accumulating suggesting that decondensed regions of the chromosomes (puffs, diffuse bands, interbands and possibly vacuoles within some bands) are generally associated with gene transcription. A model, now on the ascendancy, is based on the proposal that the band‐interband pattern is primarily a reflection of local transcriptional state, rather than the distribution of genic and non‐genic material.