Nutritional status affects 20-hydroxyecdysone concentration and progression of oogenesis in Drosophila melanogaster.
Nutritional status affects 20-hydroxyecdysone concentration and progression of oogenesis in Drosophila melanogaster.
复制标题
DOI：
10.1677/joe.1.06220
复制
发表时间：
2005-10
期刊：
影响因子：
--
通讯作者：
J. Terashima;K. Takaki;S. Sakurai;M. Bownes
中科院分区：
文献类型：
--
作者：
J. Terashima;K. Takaki;S. Sakurai;M. Bownes
果蝇产卵取决于雌性可获得的营养。当食物供应不足时，卵子发生被抑制，并且在卵子发生中期通过可能由蜕皮类固醇激素控制的机制诱导护士细胞凋亡。我们已经证明一些蜕皮激素反应基因的表达与卵室细胞凋亡相关。此外，注射蜕皮类固醇和应用保幼激素分别诱导和抑制细胞凋亡。在这项研究中，我们研究了哪些组织在营养缺乏的情况下表现出蜕皮类固醇浓度的增加，从而开始将营养摄入、激素调节以及卵室内卵子发育或细胞凋亡之间的选择联系起来。我们通过放射免疫分析法测量了全身、卵巢和血淋巴样本中的蜕皮类固醇水平，发现所有样本中的蜕皮类固醇浓度均增加。这有助于认为营养缺乏会导致果蝇体内蜕皮类固醇浓度迅速升高，并且高浓度会诱导细胞凋亡。低浓度的蜕皮类固醇对于正常的卵子发生至关重要。我们认为卵室中存在阈值浓度，当蜕皮类固醇水平超过阈值时，卵子发生中期就会诱导细胞凋亡。饥饿导致卵巢保留其产生的蜕皮类固醇，从而使单个卵室发生细胞凋亡，从而控制产生的卵子数量与食物摄入量的关系。
Drosophila egg production depends upon the nutritional available to females. When food is in short supply, oogenesis is arrested and apoptosis of the nurse cells is induced at mid-oogenesis via a mechanism that is probably controlled by ecdysteroid hormone. We have shown that expression of some ecdysone-response genes is correlated with apoptosis of egg chambers. Moreover, ecdysteroid injection and application of juvenile hormone induces and suppresses the apoptosis, respectively. In this study, we investigated which tissues show increases in the concentration of ecdysteroids under nutritional shortage to begin to link together nutrient intake, hormone regulation and the choice between egg development or apoptosis made within egg chambers. We measured ecdysteroid levels in the whole body, ovaries and haemolymph samples by RIA and found that the concentration of ecdysteroid increased in all samples. This contributes to the idea that nutritional shortage leads to a rapid high ecdysteroid concentration within the fly and that the high concentration induces apoptosis. Low concentrations of ecdysteroid are essential for normal oogenesis. We suggest there is threshold concentration in the egg chambers and that apoptosis at mid-oogenesis is induced when the ecdysteroid levels exceed the threshold. Starvation causes the ovary to retain the ecdysteroid it produces, thus enabling individual egg chambers to undergo apoptosis and thus control the number of eggs produced in relation to food intake.