Photoperiodic control of diapause termination was systematically investigated in Pseudopidorus fasciata. In 24 h light-dark cycles, the rate of diapause termination in this species depended on photoperiod. The critical night length (CNL) for diapause termination was 10 h, 0.5 h shorter than that for diapause induction. Night-interruption experiments with T = 24 showed that diapause was effectively terminated when the scotophases separated by light pulse were shorter than the critical night length (10 h); no developing individuals were found if the duration of the pre-interruption scotophase or the post-interruption scotophase exceeded the CNL. A 15-min light pulse was sufficient to reverse the effect of long night when it was placed 8 h after lights-off. Resonance experiments with a constant photophase of 12 h or 16 h and various scotophases of 4-80 h showed an hourglass-type photoperiodic response, where no rhythmicity was found. In another resonance experiment with constant scotophase of 8 h and various photophases of 4-72 h, all individuals developed into cocoons. In the Bünsow experiment, the response curve showed two apparent peaks for diapause termination, one being 8 h after lights-off, and another 8 h before lights-on. However, there was no periodic rhythmicity, which again indicates an hourglass principle. The results lead to the conclusion that the same photoperiodic clock mechanism (a long-night measuring hourglass) is involved in both diapause induction and termination.
Progeny of the flesh fly Sarcophaga bullata exposed to short day length show a maternal effect that prevents the expression of pupal diapause. Although ecological aspects of this effect are well studied, not enough is known about the molecular mechanisms underlying this maternal effect. In this study, two-dimensional electrophoresis was performed to detect differences of the abundance of certain proteins in the ovaries of this fly kept under long day and short day conditions for 2 days after eclosion. Eleven proteins that were abundant and showed significant changes were selected for mass spectrometric identification. Ovary proteins that increased in abundance under short-day conditions were similar to twinstar CG4254-PA, muscle protein 20-like protein, GA13413-PA, gene analogous to small peritrophins (Gasp CG10287-PA) and Ribosomal protein LP1 CG4087-PA. Ovary proteins that decreased in abundance under short-day conditions were similar to the ATP synthase beta subunit, fk506-binding protein and storage protein-binding protein. The 2-D proteome maps included 2 additional unknown proteins that were more abundant and 1 that was less abundant in the ovaries of 2-day old short-day females. Twinstar CG4254-PA, muscle protein 20-like protein and GA13413-PA harbour an actin-binding domain. That the 3 actin-binding proteins increase in abundance suggests that it is likely that an alteration in the actin cytoskeleton is involved in this maternal effect in the flesh fly., Aiqing Li ... [et al.]., and Obsahuje seznam literatury