Comparative study of protein synthesis and heat-shock puffing activity in Drosophila salivary glands treated with chloramphenicol.

The effects of chloramphenicol (CAP) on puffing activity and incorporation of tritiated amino acids in proteins synthesized by cultured larval salivary glands of Drosophila melanogaster were examined. CAP concentrations exceeding 1 mM were found to inhibit cellular protein synthesis and to induce the special group of heat-shock puffs in the polytene chromosomes. Recovery from a transient treatment with 5 mM CAP for 120 min led to rapid regression of the puffs and resumption of protein synthesis giving a pattern of labelled polypeptides similar to that produced by cells submitted to a temperature shift from 25 to 37 degrees C. Only slight inhibition of protein synthesis was found with thiamphenicol, the methylsulphonyl analogue of CAP, which induced a single puff in the 93D region, but did not alter the pattern of polypeptides. In contrast to the results obtained with CAP, recovery from a transient inhibition of protein synthesis by cycloheximide led to the synthesis of normal proteins as produced by control cells at 25 degrees C. Different effects of CAP which may interfere with protein synthesis and puffing activity are discussed.