ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- All Subjects: Biology
- Genre: Masters Thesis
Description
Though for most of the twentieth century, dogma held that the adult brain was post-mitotic, it is now known that adult neurogenesis is widespread among vertebrates, from fish, amphibians, reptiles and birds to mammals including humans. Seasonal changes in adult neurogenesis are well characterized in the song control system of song birds, and have been found in seasonally breeding mammals as well. In contrast to more derived vertebrates, such as mammals, where adult neurogenesis is restricted primarily to the olfactory bulb and the dentate gyrus of the hippocampus, neurogenesis is widespread along the ventricles of adult amphibians. I hypothesized that seasonal changes in adult amphibian brain cell proliferation and survival are a potential regulator of reproductive neuroendocrine function. Adult, male American bullfrogs (Rana catesbeiana; aka Lithobates catesbeianus), were maintained in captivity for up to a year under season-appropriate photoperiod. Analysis of hormone levels indicated seasonal changes in plasma testosterone concentration consistent with field studies. Using the thymidine analogue 5-bromo-2-deoxyuridine (BrdU) as a marker for newly generated cells, two differentially regulated aspects of brain cell neogenesis were tracked; that is, proliferation and survival. Seasonal differences were found in BrdU labeling in several brain areas, including the olfactory bulb, medial pallium, nucleus accumbens and the infundibular hypothalamus. Clear seasonal differences were also found in the pars distalis region of the pituitary gland, an important component of neuroendocrine pathways. BrdU labeling was also examined in relation to two neuropeptides important for amphibian reproduction: arginine vasotocin and gonadotropin releasing hormone. No cells co-localized with BrdU and either neuropeptide, but new born cells were found in close proximity to neuropeptide-containing neurons. These data suggest that seasonal differences in brain and pituitary gland cell neogenesis are a potential neuroendocrine regulatory mechanism.
ContributorsMumaw, Luke (Author) / Orchinik, Miles (Thesis advisor) / Deviche, Pierre (Committee member) / Chandler, Douglas (Committee member) / Arizona State University (Publisher)
Created2012
Description
Mealworms (Tenebrio molitor), the larval stage of yellow mealworm beetles, are a popular feeder insect for birds, amphibians, reptiles, fish, and even human populations throughout the world. As such, the goal of this work was to understand how the diet of mealworms impacts their nutritional quality as variations in quality can impact the animals (and humans) that consume them. In this study, 500 mealworms were divided among each of the following substrates designed to model food sources available in urban versus rural, more natural areas: 100% wheat germ (control); 100% Styrofoam; mixture of soil, grasses, and leaves from urban lawns; a mixture of soil, grasses and leaves from rural lawns; 50% mixture of wheat germ + carrots; natural fertilizer; or fertilizer with weed killer. The mealworms were maintained at room temperature and the diets were replaced bi-weekly to prevent spoilage and to remove mealworm waste. Once a week for three weeks, mealworms were sampled from each substrate and frozen at -20°C. After 3 weeks, mealworms housed in wheat germ + carrots weighed significantly more than all other groups (p<0.05), whereas those housed in Styrofoam or urban lawn substrates weighed significantly less at week 3 as compared to week 1 (p<0.01). The urban lawn substrate resulted in greater molting and contained the highest number of pupae, but also the greatest mortality among the substrates. The Bradford method measured the total protein content of mealworms homogenized in phosphate-buffered saline. Mealworms maintained on wheat germ had significantly greater total protein content as compared to mealworms transitioned to any other diet (p<0.05). So, compared to wheat germ, urban foods generally reduced protein, total sugars, and crude fat, although they also decreased oxidized lipoproteins. Urban lawn had lower oxidized lipoprotein content than wheat germ, but levels were higher compared to wheat germ with carrots and natural fertilizer. In addition, urban foods generally increase the water content in mealworms. Urban foods were not much different from rural lawns as no there was difference between urban and rural lawns. Differences in body mass and total protein support the hypothesis that mealworms' nutritional quality is altered by ingesting urban substrates. These data suggest that mealworms (and potentially other insects) in cities may be exposed to food substrates that result in less nutritional value than those living in more natural areas as mimicked by the rural lawn substrates and wheat germ control, although they may be higher in water content.
ContributorsLockett, Rory Earle (Author) / Sweazea, Karen (Thesis advisor) / Deviche, Pierre (Committee member) / Senko, Jesse (Committee member) / Arizona State University (Publisher)
Created2024