Regulation of Digestion in Blood-Sucking Insects

在蚊子中，蛋白质从血粉转化为蛋黄蛋白和脂质， 卵母细胞是生殖周期的重要组成部分。埃及伊蚊吸血 在中肠、脂肪体和卵巢中引发一系列事件。雌性蚊子摄取的食物超过 他们在短时间内在血液中的体重，然后花了接下来的36小时转换氨基酸， 将血液中的蛋白质转化为卵子的成分，这一过程被称为卵黄发生。该过程开始于 中肠与血粉蛋白的消化和消化酶合成的调节， 中肠发育分两个阶段。早期阶段在进食后立即开始，包括 翻译的激活。早期胰蛋白酶的合成是这一阶段的模型。晚期 开始于餐后6-8小时，涉及转录激活。晚期胰蛋白酶的合成 作为这一阶段的典范。在这项建议中，我们寻求资金，继续就监管机制开展工作， 雌蚊吸血后中肠消化酶的合成。我们提议下列 两个具体目标： 1.研究蛋白餐后早期胰蛋白酶mRNA翻译激活的机制。 在血液餐后的前30分钟内，肽或小分子存在于全身 提取物，这使得在体外中肠准备主管早期胰蛋白酶翻译。30分钟后， 在中肠中启动磷酸化级联反应，其导致早期胰蛋白酶翻译的激活。 我们建议分离和表征中肠中诱导翻译能力的因子， 表征导致早期胰蛋白酶翻译激活的信号传导过程。我们亦建议 研究内质网螺旋在调节分泌蛋白合成中的作用， 中肠 2.探讨晚期胰蛋白酶基因的转录调控机制。之后约6小时 进食时，启动中肠中的晚期胰蛋白酶转录。我们最近发现，蜕皮激素， 从喂养的蚊子的脂肪体制备的提取物中存在的未表征的因子，涉及晚期 胰蛋白酶基因诱导我们提出的特点机制蜕皮激素调节晚胰蛋白酶 表达，并确定脂肪体因子和磷脂酰肌醇3-激酶（PI-3 K）信号转导在 调节晚期胰蛋白酶转录。

In mosquitoes, the conversion of protein from a blood meal into yolk proteins and lipids for the developing oocytes is an essential part of the reproductive cycle. Blood feeding by a female Aedes aegypti mosquito initiates a series of events in the midgut, the fat body and the ovaries. Female mosquitoes ingest more than their own weight in blood in a short time and then spend the next 36 hours converting the amino acids from the blood proteins into the constituents of their eggs, a process termed vitellogenesis. The process begins in the midgut with the digestions of blood meal proteins and the regulation of digestive enzyme synthesis in the midgut opcurs in two phases. The early phase begins immediately after ingestion of the meal and involves activation of translation. The synthesis of early trypsin serves as.a model for this phase. The late phase begins 6-8 hours after the meal and involves activation of transcription. The synthesis of late trypsin serves as a model for this phase. In this proposal we seek funds to continue work on the mechanism of regulation of digestive enzyme synthesis in the female mosquito midgut following a blood meal. We propose the following two specific aims: . 1. Investigate the mechanism of activation of translation of the early trypsin mRNA following a protein meal. During the first 30 minutes following a blood meal, a peptide or small molecule is present in whole body extracts, which makes an in vitro midgut preparation competent for early trypsin translation. After 30 minutes, a phosphorylation cascade is initiated in the midgut which leads to activation of translation of early trypsin. We propose to isolate and characterize the factor that induces translational competency in the midgut, and to characterize the signaling processes that lead to activation of early trypsin translation. We also propose to investigate the role of the endoplasmic reticulum whorls in regulating secretory protein synthesis in the midgut. 2. Investigate the mechanism of transcriptional regulation of the late trypsin gene. About 6 hours after feeding, late trypsin transcription in the midgut is initiated. We have recently found that ecdysone, and an uncharacterized factor present in extracts prepared from fat bodies of fed mosquitoes, are involved in late trypsin gene induction. We propose to characterize the mechanism of ecdysone regulation of late trypsin expression, and to identify the fat body factor and the role of phosphoinositide 3-kinase (PI-3K) signaling in modulating late trypsin transcription.