Specific induction of the 93D puff in polytene nuclei of Drosophila melanogaster by colchicine

Abstract

When salivary glands of late 3rd instar larvae of D. melanogaster are exposed in vitro to colchicine (100 μg/ml) or colcemid (I to 100 Iμg/ml) for 40 min at 24°C, ³H-uridine incorporation in polytene chromosomes is severely inhibited while that in nucleolus remains nearly unaffected. At the same time, the 93D puff, which is one of the major heat shock locus, is specifically induced without a concomittant induction of other heat shock loci. These effects of colchicine or colcemid treatment are strikingly similar to those of benzamide [Lakhotia & Mukherjee, Chromosome, 81 (1980) 125]. It appears that the colchicine-induced activity of 93D is not due to the effects of this alkaloid on cellular rnicrotubules. The 93D puff is much less induced when the glands are heat shocked in presence of colchicine. Presence of colchicine during heat shock also causes the 87C puff to be induced to a greater degree (nearly 2.5 x) than its duplicate locus at 87A.