Browsing Chemistry and Biochemistry by Subject "Zoology"
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Identification And Function Of Male Moose Urinary PheromonesOlfactory communication and associated scent-marking activities play a major role in the behavioral ecology of many mammals. During the mating season (rut), scent marking associated with urine of male cervids is an important chemical cue to relay information to conspecifics. Specifically, adult male moose (Alces alces) dig rutting pits in which they urinate, and females respond strongly to urine deposited in pits. A behavioral bioassay was developed to aid in the identification and function of adult male moose urinary pheromones, which elicited the behaviors observed in females during rut. Several behavioral bioassays were conducted to delineate the putative pheromones(s). It was experimentally established that when female moose were presented with urine from the pre-rut and rut periods, females preferred the urine from rut. Moreover, this experiment documented that females responded markedly to constituent(s) in rut urine by wallowing. Rut urine can be chemically extracted and maintain its bioactivity when presented to female moose, the partition of the urine that had bioactivity was delineated. Information was provided on the chemical and physical nature of the chemosignal---not a protein, or carbohydrate, relatively non-polar, and of low molecular weight. Urinary constituents that may function as the putative pheromone(s) were characterized. Some of the chemical differences that existed in rut urine and may not function as chemical signals were eliminated. Also provided, was evidence that female moose may utilize the main olfactory system to detect chemosignals present in rut urine.
Molecular systematics and biogeography of long-tailed shrews (Insectivora: Sorex) and northern flying squirrels (Rodentia: Glaucomys)Insight into phylogenetic and biogeographic relationships among several mammalian taxa in western North America was provided with DNA sequences of two mitochondrial genes (cytochrome b and ND4). Members of two species complexes of long-tailed shrews (genus Sorex ) and northern flying squirrels (genus Glaucomys) were examined, and a common theme of responses to past climate change and glacial cycles was evident. Diversification events indicated by the DNA sequences provide new perspectives regarding the deep and shallow history of these taxa. Analysis of seven species of the Sorex cinereus complex (and related species) revealed two major clades within the complex, Northern and Southern. These generally corroborate proposed morphological relationships and correspond to broadly defined habitat affiliations (xeric and mesic), respectively. Within the Northern clade, amphiberingian species represented a monophyletic group suggesting Beringia was a center of endemism. Next, five species of the S. vagrans complex and related species were assessed. Significant molecular variation was revealed that does not correspond to morphological differences within the complex. Two major clades within S. monticolus were observed, a widespread Continental clade (Arizona to Alaska, including S. neomexicanus) and a restricted Coastal clade (Oregon to southeast Alaska, including S. bairdi and S. pacificus). A regional examination of genetic variation in the northern flying squirrel in southeast Alaska was also performed. Results suggested that southern islands in the Alexander Archipelago were the result of recent colonization (founder event). Finally, a comparative phylogeographic analysis of a reduced data set (S. monticolus), a molecular data set for the American Pine Marten, Martes americana, and other published molecular studies were used to reexamine the role of glacial refugia in the biogeography of the north Pacific coast. Previous ideas regarding purported refugia may be overstated and may be the result of limited geographic sampling. This thesis provides new perspectives on processes (e.g., post-glacial colonization) driving mammalian phylogenetic and biogeographic structuring in western North America.
Nmda Receptors In Hibernating Arctic Ground SquirrelsHibernation is a unique physiological state characterized by suppressed metabolism and body temperature that is interrupted by multiple, brief periods of arousal throughout the hibernation season. Blood flow fluctuates during hibernation and arousal in a reperfusion-like manner without causing neurological damage. Previous studies show that hippocampal slices from hibernating animals tolerate experimental oxygen nutrient deprivation and N-methyl-D-aspartate (NMDA) toxicity better than slices from euthermic animals. However, the cellular mechanisms underlying these examples of tolerance remain unclear. Tolerance to NMDA toxicity suggests that modulation of NMDA receptors (NMDAR) contributes to intrinsic tissue tolerance in slices from hibernating Arctic ground squirrels (hAGS, Spermophilus parryii). NMDAR are one subtype of glutamate receptors. NMDAR play critical roles in excitatory synaptic transmission, synaptic plasticity, learning and memory, and excitotoxicity. NMDAR1 (NR1) is a fundamental subunit of NMDAR and required for receptor function. The main focus of the current project was to test the hypothesis that NMDAR are down-regulated in hAGS compared with interbout euthermic AGS (ibeAGS) and to explore the potential mechanisms of this down-regulation. NMDAR function can be modulated by protein phosphorylation, subunit composition, and internalization. Hence, the aim of chapter 2 was to determine the distribution of NRl in hAGS and ibeAGS using immunohistochemistry. The aim of chapter 3 was to examine NMDAR function in cultured hippocampal slices from hAGS, ibeAGS, and rats using calcium imaging, and to investigate potential modulation of NMDAR such as phosphorylation and internalization for altered function using western blot analysis. Given that synaptic remodeling and functional changes after arousal from hibernation, and NMDAR play an important role in learning and memory, the aim of chapter 4 was to address the effects of hibernation on learning and memory in AGS using an active avoidance task. Here, we report that NMDAR in hAGS are down-regulated via decreased phosphorylation of NR1. This down-regulation is not due to changes in NR1 distribution and internalization. In addition, the fraction of NR1 in the functional membrane pool in AGS is less than in rats. These findings provide evidence that modulation of NMDAR contributes to neuroprotection observed in hAGS.
Sled Dogs As A Sentinel And Model For Nutritional And Physiological Adaptation In The Circumpolar NorthSled dogs were investigated as a sentinel in studying adaptation to the circumpolar north. Exploratory data were collected to study the characteristics of melatonin and thyroid hormone and revealed an impact of day length, exercise and thermoregulation on production. Before western diets, circumpolar people had a low incidence of obesity, diabetes, and cardiovascular disease. Contrary to the risks associated with a high fat, high protein diet, health benefits can be attributed to a diet rich in omega-3 fatty acids and antioxidants, offered from subsistence foods. While subsistence diets have been shown to provide substantial health benefits, there are also risks associated with them as a result of industrialization and the widespread distribution of chemicals in the environment. Native people and their sled dogs are exposed to a variety of contaminants that have accumulated in the fish and game that they consume. The sled dogs in these villages are maintained on indigenous food, primarily salmon, and therefore they can be used as models for researching the effects that a subsistence diet might have on immune parameters. Several biomarkers of immune function and inflammation were measured in village sled dogs along the Yukon River. A reference kennel, maintained on a nutritionally balanced commercial diet, was also measured in all projects for comparison. The health indicators such as antioxidant status were inversely correlated with mercury exposure.