Haemolymph ecdysteroid in the housefly,Musca domestica,during oögenesis and its relationship with vitellogenin levels |
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Authors: | TS Adams HH Hagedorn GD Wheelock |
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Institution: | 1. Metabolism and Radiation Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Fargo, ND 58105 U.S.A.;2. Department of Entomology, Cornell University, Ithaca, NY 14853, U.S.A. |
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Abstract: | Ecdysteroid titre in the haemolymph of the housefly, Musca domestica, cycled during oögenesis and peaked at ~50 pg/μl during stages 5, 6 and 7. Levels of 10–20 pg/μl were found in houseflies with pre- and post-vitellogenic ovaries. Removal of the corpus allatum and corpus cardiacum complex resulted in low ecdysteroid levels (10 pg/μl). Ovariectomized flies also had lower ecdysteroid levels than the controls at 2 days (5 pg/μl) after emergence but not at 6 days (22 pg/μl). It is possible that the ecdysteroid peak that occurred during stages 5, 6 and 7 was produced by the ovaries because ovaries secreted and synthesized ecdysteroid in vitro. Endogenous haemolymph ecdysteroid levels had a linear correlation with the amount of vitellogenin that held for hormone concentrations of 5–43 pg/μl. Furthermore, the injection of 20-hydroxyecdysone at doses of 10 ng?1.0 μg/fly increased the amount of vitellogenin from 6 h to 12 h after injection; by 24 h, the vitellogenin returned to control levels. When 20-hydroxyecdysone was injected into ovariectomized flies, it was rapidly degraded and 96% was cleared from the haemolymph within 1 h. |
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Keywords: | Ecdysteroid oögenesis vitellogenin |
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