Malpighian Tubule Transport Physiology: Mechanisms and Regulation

该项目的总体目标是确定和表征黄热病蚊子（埃及伊蚊）马氏管中完整主细胞自然环境中的电流产生和电流耗散传输系统。在基底外侧细胞膜中，目的是表征K通道以及推定的Na和Ca通道。在顶端膜中，重点是通过V型H+-ATP酶产生电流，测试电压和泵的两种底物H和ATP的影响。调查电流是如何消散在这个膜可能会导致发现一个新的家庭antiporters.Outside主细胞，补助金提出的特点，由Cl在transepithelial分泌的分流的性质。有待检验的一个假设是，星状细胞作为分流途径。另一种假设认为昆虫分隔连接提供了一个细胞旁途径的Cl。他们的假设模型提出，隔连接处有一个类似Cl通道的结构，该结构受利尿肽leucokinin的调节。本实验描述了昆虫马氏管主细胞中质子泵、通道、共转运体和反向转运体是如何通过跨细胞途径将Na和K分泌到小管腔中的。对分流途径的研究将揭示Cl是如何分泌的，总之，这些研究将揭示上皮转运的分子构建块的组合排列：泵、通道、载体和接头，以及它们如何相互作用以将NaCl、KCl和水分泌到小管腔中。在完整细胞中ATP驱动泵的拟议研究结果将引起生物学家的广泛兴趣。

The overall goal of this project is to identify and characterize current-generating and current-dissipating transport systems in the natural environment of an intact principal cell in the Malpighian tubule of the yellow fever mosquito (Aedes aegypti). In the basolateral cell membrane, the aim is to characterize K channels, and putative Na and Ca channels. In the apical membrane, the focus is on current generation by the V-type H+-ATPase, testing the effects of voltage and the two substrates of the pump, H and ATP. Investigating how current is dissipated across this membrane may lead to the discovery of a new family of antiporters.Outside principal cells, the grant proposes to characterize the nature of the shunt taken by Cl during transepithelial secretion. One hypothesis to be tested is that the stellate cell serves as the shunt pathway. The alternate hypothesis considers insect septate junctions to offer a paracellular pathway for Cl. They hypothetical model proposes that septate junctions house a Cl channel-like structure that is regulated by the diuretic peptide leucokinin.Experiments described in this proposal will demonstrate how proton pump, channels, symporters and antiporters are organized in principal cells in insect Malpighian tubules to secrete Na and K into the tubule lumen via a transcellular path. Studies of the shunt pathway will show how Cl is secreted, presumably via a paracellular path. Together, these studies will reveal the combinatorial arrangement of the molecular building blocks of epithelial transport: pumps, channels, carriers, and junctions and how they interact to secrete NaCl, KCl, and water into the tubule lumen. Results from the proposed studies of an ATP-driven pump in an intact cell will be of wide interest to biologists.