title: 20-hydroxyecdysone stimulates tissue-specific yolk-protein gene transcription in both male and female Drosophila.
abstract: The yolk polypeptides of Drosophila are normally synthesized in the fat body and ovarian follicle cells of adult females. In response to 20-hydroxyecdysone males synthesize yolk polypeptides. The actual level of yolk polypeptides synthesized in males is not always a direct reflection of the YP-transcripts present. Initially YP-transcripts are efficiently translated into polypeptides whereas later they are not and the YP-transcripts can have a half-life of less than 8 h in males. We suggest that the expression of the genes coding for the yolk polypeptides in males may be regulated at transcriptional and translational levels. Treatment of females with 20-hydroxyecdysone leads to a transient increase in YP-transcript accumulation, but the response is difficult to assess in whole flies due to the high variability in transcript levels during normal development. Analysing the response to 20-hydroxyecdysone at the level of specific tissues shows that transcript accumulation is dramatically increased in body walls (fat-body cells, epidermis and oenocytes) of both males and females. Gut, Malpighian tubules, testis and ovaries are not affected. Treatment of females with 20-hydroxyecdysone followed by measuring YP-transcript accumulation over the next 24 h in ovaries and body walls separately, confirms that only body walls respond to the hormone. There is an increase in yolk-polypeptide synthesis during the period of increased YP-transcript accumulation in females. We conclude that the response of the YP-genes to 20-hydroxyecdysone is tissue-, but not sex-specific.
mesh_terms: D000818:Animals; D004330:Drosophila / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D004441:Ecdysterone / Q000494:pharmacology*; D005260:Female; D008297:Male; D010452:Peptide Biosynthesis; D010455:Peptides / Q000235:genetics*; D014176:Protein Biosynthesis; D012313:RNA / Q000032:analysis; D014158:Transcription, Genetic / Q000187:drug effects*; D015017:Yolk Sac / Q000378:metabolism
chemical_list: D010455:Peptides; D004441:Ecdysterone; D012313:RNA