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Elucidation of Endocrinological Mechanisms during Tick Vitellogenesis

蜱卵黄发生过程中内分泌机制的阐明

基本信息

批准号：
16580035
负责人：
TAYLOR De Mar
金额：
$ 2.37万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

Vitellogenesis appears to be regulated by ecdysteroids in ticks. Ecdysteroids may function by forming a complex with a heterodimer of two nuclear receptors, ecdysteroid receptor (EcR) and retinoid X receptor (RXR). In previous studies, mated females of Ornithodoros moubata showed several peaks of high ecdysteroid titers with vitellogenin (Vg) synthesis and egg maturation after engorgement, whereas virgin females showed very low levels of ecdysteroids with no peaks, lower levels of Vg synthesis and no egg maturation. These results indicate a role for ecdysteroids in the regulation of tick Vg synthesis and egg maturation but in order to clarify this role in O.moubata we compared the EcR and RXR expression patterns in vitellogenic mated and virgin female ticks by real-time PCR. EcR and RXR expression increased soon after blood feeding in both mated and virgin females. EcR and RXR expression in mated females coincided with the high ecdysteroid titers in hemolymph. A lack of differences in EcR and RXR expression in mated and virgin females with increased ecdysteroid titers in only mated females provides further support that Vg synthesis and egg maturation are regulated by ecdysteroids.

蜱虫的卵黄发生似乎受到蜕皮类固醇的调节。蜕皮类固醇可能通过与两个核受体（蜕皮类固醇受体（EcR）和类维生素A X 受体（RXR））的异二聚体形成复合物来发挥作用。在之前的研究中，毛白钝缘鸟交配的雌性在饱腹后，随着卵黄蛋白原（Vg）合成和卵子成熟，表现出几个高蜕皮类固醇滴度峰值，而未交配的雌性则表现出非常低水平的蜕皮类固醇，没有峰值，Vg合成水平较低，并且卵子没有成熟。这些结果表明蜕皮类固醇在调节蜱 Vg 合成和卵成熟中的作用，但为了阐明 O.moubata 中的这种作用，我们通过实时 PCR 比较了卵黄发生的交配和处女雌性蜱中的 EcR 和 RXR 表达模式。在交配和未交配的雌性中，EcR 和 RXR 的表达在吸血后很快就会增加。交配雌性中的 EcR 和 RXR 表达与血淋巴中的高蜕皮类固醇滴度一致。交配和处女雌性中 EcR 和 RXR 表达缺乏差异，且仅交配雌性中蜕皮类固醇滴度增加，这进一步支持了 Vg 合成和卵子成熟受蜕皮类固醇调节。