Comparative Gastrointestinal and Renal Transport Physiology of Crustaceans

这项为期3年的研究计划是先前关于甲壳类动物胃肠道和肾脏的吸收和分泌功能的研究的继续。许多甲壳类物种正在世界各地进行大规模的水产养殖。成功地将这些动物从鸡蛋饲养到市场的主要问题之一是提供成本效益高的饲料，从而导致快速增长。在这项研究计划开始之前，人们对甲壳类肠道的吸收功能知之甚少，因此，关于提供养殖动物的人工饲料的性质，几乎没有什么建议。以前的工作使用了各种体外技术来研究这些动物的胃肠道的各种器官，以了解在正常的消化过程中营养物质、矿物质和水是如何被吸收的。目前的建议将通过表征这些动物的主要吸收器官--肝胰腺中的营养物质运输机制来扩展早期的研究。生化分离技术将被用来纯化能吸收食物成分的肠道转运膜，以研究这些吸收过程的特征，以便与更深入地研究哺乳动物的系统进行比较。此外，吸收器官的培养细胞制剂将被用来量化这些动物对糖、氨基酸和其他重要饲料化合物的跨细胞吸收速率。这项研究计划的第二个目标是研究甲壳类肾脏的营养重吸收过程，以确定它们在代谢物保存中的作用。在哺乳动物中，血液中的营养物质被肾脏过滤并有选择地重新吸收回到血液中，这样就可以排泄潜在的毒素，保存重要的营养物质。研究是否在无脊椎动物中发生相同的过程，以及确定再吸收过程的特征。类似的膜分离和纯化技术和细胞培养研究将应用于肾脏细胞，与上文讨论的肠道器官有关。这项为期三年的研究将更好地了解一组具有重要经济意义的无脊椎动物的肠道和肾脏是如何促进生物生长的。这些研究将提供关于细胞生理学的重要基本科学信息，以及可能有助于在受控条件下成功饲养这些动物的潜在有用的应用结果。

This 3-year research program is a continuation of a previous study dealing with the elucidation of the absorptive and secretory functions of the crustacean gastrointestinal tract and kidneys. Many crustacean species are undergoing extensive aquaculture throughout the world. One of the major problems with the successful rearing of these animals from egg to market is providing a cost-effective diet that leads to rapid growth. Prior to the initiation of this research program, little was known about the absorptive functions of the crustacean gut and therefore few recommendations could be made concerning the nature of an artificial diet to provide cultured animals. Previous work has used a variety of in vitro techniques to study the various organs of the gastrointestinal tract of these animals to obtain an understanding of how nutrients, minerals, and water are absorbed during normal digestive processes. The present proposal will extend earlier studies by characterizing nutrient transport mechanisms in the major absorptive organ of these animals, the hepatopancreas. Biochemical isolation techniques will be employed to purify gut transporting membranes that bring about the uptake of dietary components to study the characteristics of these uptake processes for comparison with more thoroughly investigated systems in mammals. In addition, cultured cell preparations of the absorbing organs will be used to quantify rates of transcellular absorption of sugars, amino acids, and other important dietary compounds in these animals. The second goal in this research program is to study the processes of nutrient reabsorption by the crustacean kidneys to establish their roles in metabolite conservation. In mammals nutrients in the blood are filtered and selectively reabsorbed back to the blood by the kidneys and in this way potential toxins can be excreted and important nutrients conserved. Whether the same processes occur in the invertebrates as well as defining the characteristics of reabsorptive processes will be examined. Similar membrane isolation and purification techniques and cell culture studies will be employed with kidney cells as will be associated with the gut organs discussed above. This 3-year study will provide a better understanding of how the gut and kidneys of an economically important group of invertebrates contribute to organismic growth. Important basic scientific information about cell physiology will be forthcoming from these studies, as well as potential useful applied results that may aid in the successful rearing of these animals under controlled conditions.