CHAPTER 1
At various times during metamorphosis, brain tissue of D. melanogasterhas been pulse-labeled in situ with 35S-Met. The composition of the newly synthesizedstage-specific proteins and of the total bulk of Coomassie stained polypeptidespresent at the same time in the tissue, or the parts of it, were analyzed on SDS-polyacrylamidegels.
The striking similarity and constancy of the obtained patterns, and thefinding that most of the observed accumulating polypeptides are glycosalated,lead to the conclusion that the predominant change in the larval Drosophila brainis dendritic and/or axonal reorganization.
CHAPTER II
Pupae of Drosophila melanogaster were heat shocked under conditionsrequired to induce phenocopies in more than 90% of the flies that subsequentlyemerge. The effects of these treatments on protein synthesis in two tissues (thoracicepithelium and brain) were followed for several hours after the heat treatments.Results from pulse labeling and protein separations on SDS acrylamide gels showeda virtually complete cessation of protein synthesis immediately after the shockfollowed by a non-coordinate resumption of the starting pattern. Similar experimentsfollowing double heat shocks demonstrated a more rapid resumption of synthesisof heat shock proteins after two successive heat treatments than after a singleone.
CHAPTER III
We describe variants of three heat shock proteins of Drosophila melanogasterand the use of these to map the chromosome regions which contain the codingsequences for these proteins. All three map to a region on chromosome 3L whichincludes only one heat shock puff, that designated as 67B. The results imply thatthe genes which code for at least three heat shock proteins are included withinthe 67B region.
CHAPTER IV
Mild heat treatments applied to whole animals or cell cultures of Drosophilamelanogaster prior to lethal heat shocks result in both survival and protectionagainst phenocopy induction. From an examination of these heat shock effectson transcriptional and translational activities in tissues and cells it appears thatthe protective action of pretreatment is due to sequestering of mRNAs in a maskedform as RNPs. Heat shock proteins are evidently involved in the masking processeither directly or indirectly.
