Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xxiv, 256 p.; also includes graphics (some col.). Includes bibliographical references (p. 228-256).

Thesis (Ph. D.)--University of Hong Kong, 1994. / Includes bibliographical references (leaves 128-140).

Thesis (M.Sc.)--University of Guelph (Canada), 2006. / Includes bibliographical references.

Amphipods are the most ubiquitous animals, after nematodes, on earth. Although there are several terrestrial amphipod species, most are aquatic. They are familiar animals in the water table exposed in cave environments and boreholes. The food source on which the amphipods depend was not directly observable in the cave environments frequented by the amphipods. In order to establish the role cave-dwelling amphipods play in ecology, the primary purpose of this study was thus to determine what cave-dwelling amphipods feed on. Amphipod, water and sediment samples were collected from five different caves, in the northern part of South Africa, namely Koelenhof Cave, Sterkfontein Cave, Ficus Cave, Peppercorn’s Cave, and Irene Cave. Following collection and transportation, resulting in zero amphipod mortalities, all of the samples were transferred to rectangular fish tanks stored in an environmental room, set up in such a way as to mimic the conditions in the caves as closely as possible. Long term adaptability and survival proved to be a successful undertaking, resulting in the death of only two amphipods per tank. Scanning electron microscopy was used to observe the mouthparts of the amphipods in order to begin establishing their feeding behaviour. Standard microtechniques were carried out to establish the general histological orientation and histology of the gastrointestinal tract. A Histochemical Fluorescent staining method was employed, and a reddish-orange fluorescence was observed, thereby indicating the presence of mucous in the GIT. Several feeding experiments were carried out, and it was established that on average amphipods can survive without a food source for a maximum of sixty ABSTRACT xv days. Through a series of different feeding experiments, it was determined that amphipods ingest bat faeces, leaf litter, sediment and yeast, with leaf litter producing the highest rate of survival. It was also observed that amphipods, regardless of body size, are predators, scavengers, and cannibals, which may provide an explanation as to why amphipods display evasive behaviour. Microbiology plays a vital role in determining what amphipods feed on, and therefore water, soil, and digestive contents of amphipods were studied using a wide array of microbiological analyses: Heterotrophic Plate Counts; Total Coliforms; Faecal Coliforms; Faecal Streptococci; Confirmatory test for Escherichia coli; Detection of Clostridium, Pseudomonas, and Salmonella. According to the South African Bureau of Standards, the quality of the water contained within all four of the caves in this study may not be used for human consumption prior to undergoing various purification processes. Once the role that cave-dwelling amphipods play in ecology has been firmly established it may then be possible to make use of amphipods as biological indicators, because since they inhabit cave streams and groundwater and are sensitive to pollutants, declines in their populations could indicate a decline in the water quality in their streams and surrounding groundwater supply. / Dr. J.F. Durand

There is a need for a simple, safe, reproducible and non-invasive method for studying upper gastrointestinal motility in humans. Existing methods, measuring electrical contractions and intraluminal pressure changes have limitations in their correlation with the physiology of what is actually happening to ingested food. Transit time has been suggested as a more physiologic means of studying gut motility; therefore a method was developed to measure transit time and secretory changes in response to ingested liquids, using ileostomy patients. 2.5 gm of polyethylene glycol (PEG) was added to 500 ml of normal saline, and given orally to volunteers with ileostomies. The ileostomy effluent was collected for 2 hours in 10 minute aliquots. PEG assay was performed by the turbidimetric method of Hyden, using Malawer's modification with an emulsifier. The following were measured: most rapid, mode, median, mean and total transit t imes. A study was then performed to determine if different foodstuffs -carbohydrate, fat, and protein - produce measurable changes in transit time. 2.5 gm of PEG was added to 500 ml of (a) 90 ml Lipomul in 410 ml normal saline (b) 5% dextrose (c) 100 ml of Travasol 10% in 400 ml distilled water. The volumes were chosen to produce isoosmolar test feeds. Validating studies showed satisfactory reproducibility and individual variation (r = 0.68 for volume recovery, r = 0.69 for PEG recovery, p = < 0.5) The recovery pattern of a test feed of 500 ml normal saline was found to follow a skew distribution, with mode, median and mean transit times all different. The most reproducible and easily measured was mode, or peak, transit time (average 40 minutes for volume and PEG recovery). Significant delays in all transit times were found (p = < 0.01) using each of the test feeds: (a) for Lipomul a peak volume recovery of 60 minutes and PEG recovery of 70 minutes; (b) for 5% dextrose a peak volume recovery of 90 minutes and PEG recovery of 90 minutes; (c) with Travasol, negligible amounts of ileostomy output were obtained over 2 hours. The most rapid transit time was consistently less than 10 minutes, as measured by PEG appearance from the ileostomy. This is far less than previously described by standard methods, but is in accordance with transit times measured to the ileocaecal valve in intact gastrointestinal tracts using the recently-introduced breath hydrogen method following lactulose ingestion. Comparison of total volume recovery with total PEG recovery over 2 hours indicates whether net absorption or secretion has occurred: (a) with normal saline a volume recovery of 62% and PEG recovery of 48% indicates net secretion; (b) with Lipomul a volume recovery of 66% and PEG recovery of 58% also indicates net secretion, with no significant difference from normal saline (p = < 0.05); (c) with 5% dextrose a volume recovery of 4% and PEG recovery of 13% indicates net absorption, significantly different from normal saline (p = < 0.01); (d) for Travasol a volume recovery of 1% and PEG recovery of 1% indicates no net absorption or secretion, but confirms the above finding of a very large delay in transit time. These studies have shown that isotonic solutions of normal saline, glucose, fat and protein result in widely different peak transit times in ileostomy patients. They also result in widely different fluid outputs from the ileostomy due to net absorption or secretion. These differences have not been described before. / Surgery, Department of / Medicine, Faculty of / Graduate

A study on the digestive tract of a harpacticoid copepod, 2i3lio£Ss californicus, was carried out using techniques of light and electron microscopy. It was found that a curved, cuticulized esophagus extends from the ventral mouth to the midgut. Its musculature and shape allows fairly large food particles to enter the gut. The noncuticulized portion of the digestive tract consists of; 1. A single, anterior, spherical midgut caecum, 2. An anterior midgut extending from the midgut caecum to the joint at the beginning of the urosome, 3. A posterior midgut extending almost the length of the urosome. The cuticulized hindgut can be divided, structurally, into anterior and posterior regions. It is suggested that the anterior hindgut functions in ion and water regulation as well as begins the formation of a faecal pellet. The posterior hindgut compacts the faecal pellet and retains it until defaecation. At the light and electron microscope levels four cell types could be distinguished. By studying the cell's position in the gut, electron density, amount of lipid, amount and type of vesiculation and the abundance and position of the cell*s organelles, functions for these cells were determined: 1. cell type one is an embryonic cell which will replace cells worn away or lost in secretion. 2. Cell type two functions mainly in the synthesis and secretion of proteins and also plays a role in lipid absorption. 3. Cell type three appears to function mainly in lipid absorption. 4. Cell type four also functions in lipid absorption but this cell is only found in the anterior midgut and the type of vesicles found in this cell suggest a different type of absorption is occurring than in cell type three. From the abundance of each cell type, the length of the microvilli, the development of the basal lamina and luminal projections, the following conclusions were made: 1. The midgut caecum functions mainly for absorption of digested nutrients. 2. The anterior midgut also functions for nutrient absorption but plays a more important role in merocrine and exocrine secretion. The presence of concretions in cell types two and three of the anterior midgut suggest a role in excretion, water or ion regulation. 3. The posterior midgut functions mainly in absorption, though some holocrine secretion is evident. / Science, Faculty of / Botany, Department of / Graduate

No description available.

Thesis (M.Sc.)--University of Wollongong, 2005. / Typescript. Includes bibliographical references: leaf 118-127.

published_or_final_version / Physiology / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Surgery / Doctoral / Doctor of Philosophy