The induction of changes in chromosomal activity in different polytene types of cell in Drosophila hydei

Abstract

The puffing patterns of 116 puffs occurring both in salivary glands and stomach were compared at a stage from 10 to 6 hours before puparium formation: 61.2% of the puffs did not show significant differences in activity between the two tissues; 6.0% of the puffs showed active puffing in stomach cells only; and 3.4% were restricted to salivary gland cells. The remaining 29.4% of the puffs, though active in both tissues at this time, became active earlier in the stomach and reached the same activity level in the salivary glands only at later stages of development; 70.6% of these puffs were found to be specifically active during the stage just before puparium formation. The changes in puffing pattern during normal development were compared with the changes induced in the two tissues by temperature shocks. The differences between the two tissues observed during normal development could not be found following temperature shocks. Not only do all puffs in the salivary gland and in the stomach attain the same level of activity following temperature shock, but the stomach cells show these changes at the same time or even later than the salivary gland cells.