Cellular and molecular mechanisms of ion transport and excretion in insect and crustaceans

这项研究考察了运输上皮细胞如何排泄毒素，并调节昆虫和甲壳类动物体内的水、离子、酸和碱的水平。上皮是在两个隔室之间形成屏障的细胞层，它运输无机盐(钠、氯化物等)等物质。和水之间的一个充满流体的隔室，通常是外部，和第二个内部隔室。外部隔室中的液体的例子包括流经水生物种鳃上的水、消化道的内容物以及排泄系统中包含的尿液或血液滤液。内部隔室中的液体包括血液和细胞外液体，这些液体将营养物质输送到肠道和排泄系统，或从肠道和排泄系统输送营养物质。分泌或重新吸收来自特定隔室的离子、营养、废物、毒素或水的上皮细胞的活动可以由释放到循环系统的激素来控制。这些激素与细胞膜上的受体结合，激活细胞内的第二信使系统。这一连串的信号经常导致运输特定离子的膜蛋白的激活。对昆虫上皮运输机制和调控的研究提供了三个方面的好处：1)了解昆虫上皮运输的细胞机制和激素调控有助于合理设计新的、对环境无害的防治措施。例如，了解上皮细胞排泄有毒物质的机制有助于开发阻止害虫这种排泄的化合物。2)了解上皮细胞的运输机制对于了解昆虫和甲壳类动物如何适应不同的环境，以及自然或人为的变化(如环境污染)如何对这些动物产生有害影响至关重要。3)昆虫和甲壳动物的上皮组织为了解排泄和离子转运的细胞机制提供了有用的模型系统。使用遗传特征良好的物种，如果蝇，使我们能够检查控制特定上皮转运蛋白表达的基因突变的影响。

This research examines how transporting epithelia excrete toxins and regulate the levels of water, ions, acids and bases within insects and crustaceans. Epithelia are layers of cells which form a barrier between two compartments, and which transport materials such as inorganic salts (sodium, chloride, etc.) and water between one fluid-filled compartment, often external, and a second internal compartment. Examples of fluids in external compartments include water flowing over the gills of an aquatic species, the contents of the digestive tract, and urine or blood filtrate contained within the excretory system. Examples of fluids in 'internal' compartments include the blood and extracellular fluids which transport nutrients to or from the gut and excretory system. The activities of epithelia which secrete or reabsorb ions, nutrients, waste materials, toxins or water from particular compartments can be controlled by hormones released into the circulatory system. The hormones bind to receptors in cell membranes and activate intracellular second messenger systems. This cascade of signaling often leads to activation of membrane proteins which transport particular ions. Research into the mechanisms and control of transporting epithelia in insects provides three benefits: 1) Knowledge of the cellular mechanisms and hormonal control of transporting epithelia in pest species of insect facilitates rational design of novel and environmentally-benign control measures. For example, understanding the mechanisms of excretion of toxic materials by epithelia aids development of compounds which block such excretion in pest insects. 2) Understanding the mechanisms of transporting epithelia is central to understanding how insects and crustaceans adapt to different environments, and how natural or man-made changes (e.g. environmental pollution) may have deleterious effects on these animals. 3) Epithelial tissues of insects and crustaceans provide useful model systems for understanding the cellular mechanisms of excretion and ion transport. The use of genetically well-characterized species, such as the fruit fly, allows us to examine the effects of mutations in genes controlling the expression of specific epithelial transporters.