A 28-FOLD INCREASE IN SECRETORY PROTEIN-SYNTHESIS IS ASSOCIATED WITH DNA PUFF ACTIVITY IN THE SALIVARY-GLAND OF BRADYSIA-HYGIDA (DIPTERA, SCIARIDAE)

When the first group of DNA puffs is active in the salivary gland regi ons S1 and S3 of Bradysia hygida larvae, there is a large increase in the production and secretion of new salivary proteins demonstrable by [H-3]-Leu incorporation. The present study shows that protein separati on by SDS-PAGE and detection by fluorography demonstrated that these p olypeptides range in molecular mass from about 23 to 100 kDa. Furtherm ore, these proteins were synthesized mainly in the S1 and S3 salivary gland regions where the DNA puffs C7, C5, C4 and B10 are conspicuous, while in the S2 region protein synthesis was very low, Others have sho wn that the extent of amplification for DNA sequences that code for mR NA in the DNA puffs C4 and B10 was about 22 and 10 times, respectively . The present data for this-group of DNA puffs are consistent with the proposition that gene amplification is necessary to provide some cell s with additional gene copies for the production of massive amounts of proteins within a short period of time (Spradling AC and Mahowald AP (1980) Proceedings of the National Academy of Sciences, USA, 77: 1096- 1100).