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

本研究探讨了昆虫和甲壳类动物的运输上皮如何排泄毒素并调节水、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，并在一个充满液体的隔室（通常是外部）和第二个内隔室之间运输无机盐（钠、氯化物等）和水等物质。外部隔室中的液体的例子包括流经水生物种鳃的水、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，它们将营养物质运送到肠道和排泄系统。分泌或重吸收离子、营养物质、废物、毒素或水分的上皮细胞的活动可由释放到循环系统中的激素控制。这些激素与细胞膜上的受体结合并激活细胞内第二信使系统。这种信号级联反应通常会导致运输特定离子的膜蛋白的激活。研究昆虫上皮运输的机制和控制有三个好处：1)了解昆虫有害物种上皮运输的细胞机制和激素控制，有助于合理设计新的环保控制措施。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排泄的化合物。2)了解上皮细胞的转运机制对于理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)昆虫和甲壳类动物的上皮组织为理解细胞排泄和离子运输机制提供了有用的模型系统。利用基因特征良好的物种，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.