Adams T S, Li Q J
Biosciences Research Laboratory, USDA-ARS, State University Station, Fargo, North Dakota 58105-5674, USA.
Arch Insect Biochem Physiol. 1998;38(4):166-76. doi: 10.1002/(SICI)1520-6327(1998)38:4<166::AID-ARCH2>3.0.CO;2-P.
Ovaries from house flies maintained on sucrose secrete large amounts of ecdysteroid when they are cultured with ovarian ecdysteroidogenic hormone, OEH. However, ovarian ecdysteroid secretion is reduced by incubation with both OEH and the ovarian ecdysteroidostatin (OES). A partially purified OES fraction from a semi-preparative reverse phase HPLC C18 column caused a 98% inhibition of ovarian ecdysteroid secretion in vitro at a concentration of 0.8 equivalents per microliter. Ovaries can be activated to produce ecdysteroid in vivo by feeding diet containing protein to flies maintained on sucrose. Ecdysteroid secretion was inhibited when the in vivo stimulated ovaries were cultured with OES. This suggests that OES does not interfere with the OEH activation mechanism, but blocks ovarian ecdysteroid synthesis or release. Furthermore, OES inhibition is reversible and ecdysteroid secretion resumes when OES is removed. Musca OES could explain the decrease in ecdysteroid levels found in flies after mid-vitellogenesis. Both adult male and female abdomens contain OES, but OES was not transferred to females during mating. Evidence is presented that OES is not a trypsin modulating oostatic factor.
以蔗糖为食的家蝇卵巢在与卵巢蜕皮激素生成激素（OEH）共同培养时会分泌大量蜕皮甾体。然而，与OEH和卵巢蜕皮甾体抑制素（OES）共同孵育会降低卵巢蜕皮甾体的分泌。从半制备反相HPLC C18柱中得到的部分纯化的OES组分，在浓度为每微升0.8当量时，可在体外对卵巢蜕皮甾体分泌产生98%的抑制作用。通过给以蔗糖为食的果蝇喂食含蛋白质的食物，可在体内激活卵巢产生蜕皮甾体。当体内受刺激的卵巢与OES共同培养时，蜕皮甾体分泌受到抑制。这表明OES不会干扰OEH的激活机制，而是阻断卵巢蜕皮甾体的合成或释放。此外，OES的抑制作用是可逆的，去除OES后蜕皮甾体分泌会恢复。家蝇OES可以解释在卵黄发生中期后果蝇体内蜕皮甾体水平的下降。成年雄性和雌性腹部都含有OES，但交配过程中OES不会转移到雌性体内。有证据表明OES不是一种调节卵巢静止的胰蛋白酶因子。
