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.
