Abstract
Living organisms somehow determine developmental timing in their life. Intriguingly, in Drosophila melanogaster, the prepupal period is 12 hours at standard rearing conditions suggesting that the fly has a biological timer to measure the time for pupation. Our study have defined that the transcriptional repressor Blimp-1 plays an important role in this time measuring system through regulation of precise timing of FTZ-F1 expression. To elucidate the molecular mechanism of that system in detail, we performed further analysis by changing stability, timing and levels of Blimp-1 expression using hs-Blimp-1 transgenic fly line and Blimp-1 mutant lines. Results indicated that these three factors are important to determine prepupal period and that Blimp-1 works as an hourglass timer in this period. Interestingly, prepupal period is different among Drosophila species. Examination of expression timing of Blimp-1 and ftz-f1 in D.pseudoobscura suggested that the observed difference is caused by the regulation of these genes. Thus we expect that the identified time measuring system play an important role to produce different prepupal periods in different Drosophila species.