The Role of Vacuolization in Rapid Fluid Secretion by InsectMalpighian Tubules

9807948春季液泡化是指在细胞内形成与膜结合的“囊”或液泡。在过去的30年里，在哺乳动物的肾、肝脏、乳腺和脊椎动物的附睾以及无脊椎动物的排泄器官(触角腺和马氏管)中，参与细胞运输的各种动物组织中都存在空泡，这在整个科学文献中都有记载。尽管它们的存在不再被争论，但液泡的功能和对流体运输的总体贡献仍然是推测的。斯普林博士和费尔根豪尔博士假设，这些液泡参与了跨细胞作用(液体和溶质在细胞间的移动)，并对液体的快速运输做出了重大贡献。通过使用生理学方法和显微镜(光、共聚焦扫描和透射电子显微镜)，PI的目的是根据运动方向、来源、内容、体积和目的地来表征空泡的特征。PI还将调查细胞的结构元素(细胞骨架)对空泡运动的贡献，并假设这些空泡与管腔周围的膜(根尖)融合，如果有的话，空泡对液体分泌有什么贡献，无论是直接的，还是作为改变顶膜的机制，或作为渗透压的来源。由于它们的可用性、相对容易的实验操作以及与包括肾小管在内的其他运输组织惊人的细胞相似性，家蟋蟀的马氏管为研究细胞运输提供了一个很好的模型系统。此外，板球马氏管的快速液体分泌总是伴随着广泛的空泡化。这项研究的结果将有助于我们进一步了解一般分泌过程的基本机制，应用范围从昆虫控制到脊椎动物肾脏生理学。

9807948 Spring Vacuolization refers to the formation of membrane-bound "sacs" or vacuoles within cells. Over the past thirty years, the presence of vacuoles in a variety of animal tissues involved in cellular transport, including the mammalian kidney nephron, liver, mammary glands and epididymis of vertebrates as well as the excretory organs of invertebrates (antennal glands and Malpighian tubules), has been documented throughout scientific literature. Although their presence is no longer argued, vacuole function and overall contribution to fluid transport remains speculative. Drs. Spring and Felgenhauer hypothesize that these vacuoles are participating in transcytosis (movement of fluid and solutes across cells) and contribute significantly to rapid fluid transport. By employing both physiological methods and microscopy (light, confocal scanning and transmission electron microscopy), the PIs objective is to characterize the vacuoles in terms of direction of movement, source, content, volume, and destination. The PIs will also investigate the contribution of the structural elements of the cell (cytoskeleton) to vacuolar movement and assuming that these vacuoles fuse with membrane surrounding the lumen (apical), what contribution, if any, do vacuoles make to fluid secretion either directly, or as a mechanism to alter the apical membrane, or as a source of osmolytes. The Malpighian tubules of the house cricket provide an excellent model system to investigate cellular transport due to their availability, relative ease of experimental manipulation and striking cellular similarities to other transport tissues including kidney tubules. In addition, rapid fluid secretion in cricket Malpighian tubules is always associated with extensive vacuolization. The results of this investigation will serve to further our knowledge of basic mechanisms of secretory processes in general with applications ranging from insect control to vertebrate renal physiology.