title: Variegated expression of the Sgs-4 locus in Drosophila melanogaster.
abstract: Experiments on T(1;4)wm258-21 larvae of Drosophila melanogaster are described which establish the existence of a salivary gland specific marker for position-effect variegation. The marker is a glue protein gene called Sgs-4 which is expressed during the third larval instar. Using temperature as a variegation modifier, we showed that cytological compaction for the Sgs-4 chromosomal locus is enhanced at 17 degrees C and reduced at 29 degrees C. We also found that the Sgs-4 protein and transcript from salivary glands at 17 degrees C accumulate to roughly half the levels found in salivary glands at 29 degrees C. Southern analysis suggested that the Sgs-4 locus at 17 degrees C is polytenized to roughly one-third the level at 29 degrees C. The results are discussed with respect to alternative models of variegation.
mesh_terms: D004247:DNA / Q000032:analysis; D004331:Drosophila melanogaster / Q000235:genetics* / Q000254:growth & development; D005260:Female; D005786:Gene Expression Regulation; D005967:Glue Proteins, Drosophila; D007814:Larva; D008297:Male; D010641:Phenotype; D012333:RNA, Messenger / Q000032:analysis; D012469:Salivary Glands / Q000378:metabolism / Q000648:ultrastructure; D012471:Salivary Proteins and Peptides / Q000096:biosynthesis / Q000235:genetics*; D014158:Transcription, Genetic; D014178:Translocation, Genetic
chemical_list: D005967:Glue Proteins, Drosophila; D012333:RNA, Messenger; D012471:Salivary Proteins and Peptides; D004247:DNA