<p>Scallops, a family of swimming bivalve mollusks, have dozens of eyes arrayed along the edges of their valves. Relatively little is known about the form and function of these unusual eyes. To learn more about them, we studied the visually influenced behavior of scallops, as well as the morphology and spectral sensitivity of their eyes. Of particular interest was whether or not the simple neural architecture of these animals constrains the number of visually-influenced behaviors they can perform. We were also interested to learn whether scallop eyes, despite providing relatively poor visual acuity, show optical refinements, such as corrections for spherical and chromatic aberration, that are known from the eyes of animals with better vision. In the following dissertation, Chapter 2 discusses the visually-influenced behaviors of scallops. It has been argued that bivalve mantle eyes only act as predator-detectors, but the behavioral trials described in this chapter suggest that vision may serve additional purposes in scallops. For example, it was found that visual cues relating to flow conditions may influence scallop feeding behavior. Chapter 3 presents a comparative study of scallop eye morphology. Here, it is found that eye morphology varies considerably between scallop species and that highly mobile scallops have better vision than less mobile or immobile species. Evidence is also presented that one of the two scallop retinas may perform tasks of similar importance to all species, such as predator detection, while the other retina may perform tasks more important to mobile species, such as those associated with the visual detection of preferred habitats. Chapter 4 investigates the spectral sensitivity of the two retinas in the mantle eyes of two scallop species. It is found that there is both inter- and intra-specific variation in scallop spectral sensitivity and that color perception in scallops may be influenced by both environmental light conditions and chromatic aberration caused by their lens. The research in this dissertation provides insight into how vision functions in animals that, like scallops, have a vast number of eyes, but a limited capacity for neural processing. Despite such limitations, it is evident that scallops display a wide range of visual behaviors and have eyes with highly-refined optics.</p> / Dissertation

Despite a long history of investigations on protective ant-plant interactions, since the late 19century (Thomas Belt 1874), a comprehensive quantitative understanding of the adaptations that facilitate these associations between plants and ants and the differential importance of these adaptations in predicting the benefits and costs to each partner and in shedding light on the evolutionary trajectories of this ecologically widespread interaction is yet to be realized. In the present study we have experimentally shown that the identity of the ant species (T. albipes), the abundance of this ant species and the composition of EFN produced by floral buds and young leaves of H. brunonis plant populations contribute to facilitating protection of floral bud inflorescences and young leaves of H. brunonis populations in a particular site. Of all the 16 ant species that inhabit the domatia of H. brunonis at several sites, the plant has found its protective ant partner only in the dolichoderine ant T. albipes and that too, only in the southernmost site In our experimental set up of three populations of H. brunonis at three different latitudes, where each site is separated from another site by at least 200 km, we have shown that only the southernmost population (Solaikolli) in protected by the ant species T. albipes. Although T. albipes is found in two of the three populations used in the present study (Sampaji and Solaikolli), it is present in a relatively larger abundance both within the domatia of H. brunonis and in the terrestrial stratum only in the southernmost site Solaikolli and is hence able to protect the EFN producing structures of H. brunonis at this site. In comparison, T. albipes is found in low abundance both in the domatia and in the terrestrial stratum in the site Sampaji and does not protect EFN producing plant parts of H. brunonis at this site. We have also experimentally shown that the young leaves of H. brunonis at this southernmost site Solaikolli are protected to a greater extent than the floral bud inflorescences, since T. albipes preferentially utilized EFN produced by young leaves compared to EFN produced by floral buds at this site. Moreover, we have also shown that the floral buds of H. brunonis in the northernmost site are unprotected for two reasons: i. the absence of the protective ant species T.albipes at this site. ii. The EPN produced by some of floral buds at this site is differentially utilized to a much lower extent than floral buds from other sites due to EFN from Agumbe being > 400-fold more viscous than the EFN produced by floral buds at the other two sites (sampaji and Solaikolli) (at 30º C). Although previous studies have independently shown that the identity of the ant partner (Janzen 1966, Schemske 1980, Horvitz and Schemske 1984, Heads 1986, Oliveira et al. 1987a, b; Jaffe et al. 1989, RicoGray and Thien 1989, Davidson et al. 1991) and the abundance of the protective ant species (Koptur 1984, Rocha and Bergallo 1992, Di Giusto et al. 2001) are important in predicting the protective outcome of the interaction between a plant species and its interacting ants, few studies have examined these two factors along with an examination of the EFN volume and composition (Inouye and Inouye 1980, Rudgers and Gardener 2004) and differential utilization of these qualitatively different EFNs produced by different populations of the same ant plant. Humboldtia brunonis and its interacting ant species provides a unique system to address questions about the evolution of ecological specialization and the evolution of preadapted plant traits that facilitate interactions between plants and ants (especially domatia), due to its unique polymorphism for the presence of caulinary domatia and its widespread abundance in the low-elevation wet-evergreen forests of the Western Ghats.

In salmonids, the decision to migrate or remain resident is influenced by the status, and hence condition, of individuals. Status has been suggested to arise from the temperament of fish. In this study the links between standard metabolic rate and the levels of aggressiveness and shy/boldness were examined for 0+, hatchery-raised brown trout (Salmo trutta). I hypothesized, from the results of earlier studies (Cutts et al., 1998; Yamamoto et al., 1998), that high metabolic rates (MR) would be positively correlated to levels of aggression and boldness. The study was conducted in 200 L aquaria in which aggressiveness was measured by allowing each fish to interact with a mirror image of itself, and shy/boldness was tested by measuring the amount of time a fish used before exploring a new area. Standard metabolic rate was measured in a flow-through respirometer. In contrast to my expectations, there was no correlation between the different behavioural measures and the metabolic rate of fish. Also, no correlation between boldness and aggressiveness of fish was found. In additional testing aggressiveness correlated positively with the condition of fish (in coherence with Harwood et al., 2003) but, contrary to earlier studies (Överli et al., 2004; Schjolden &amp; Winberg, 2007), not with the speed of acclimatization. The difference in results between this test and earlier studies, concerning the degree of correlation between MR and aggressiveness, suggests that the strength of this link differs between species of salmonids. Also, it may suggest changeability in the MR – behaviour link in different environments. Last, the status and condition of individuals cannot be unambiguously explained by temperament alone, but arise from a wider array of physiological and environmental factors.

In most cells, water moves across the plasma membrane by simple diffusion. However, there are specialized epithelia, such as the kidney proximal tubules, that secrete or absorb water faster than simple diffusion predicts. While the identification of a proteinacious pore that transports water was elusive for many years, the recent discovery of aquaporin-1 (AQP-1) provides a molecular mechanism for the extraordinarily high permeability to water of epithelial cells in these tissues. Like the kidney, the human eye has several epithelial-lined structures that have a high permeability to water. One of these structures, the ciliary process, secretes aqueous humor (comprised mostly of water) into the eye and is regulated therapeutically by activating α₂-adrenergic receptors (α₂-AR) on its plasma membrane. The studies presented in this dissertation are structured to address four specific aims that were designed to test the hypothesis that the AQP-1 water channels are present in the human eye and are functionally regulated by α₂-ARs. Specific aim 1 characterized the distribution of AQP-1 in the human eye by immunofluorescence microscopy using affinity purified antibodies against purified AQP-1 protein. Using standard techniques in molecular biology, specific aim 2 generated antibodies to three fusion proteins; each containing a specific region of AQP-1. After screening several cell lines from the eye and the kidney with anti-AQP-1 and anti-α₂-AR IgY, specific aim 3 identified a cell line, human trabecular meshwork (HTM) cells, that contains both the AQP-1 water channels and α₂-ARs. Lastly, specific aim 4 investigated the functional relationship between the α₂-ARs and AQP-1 water channels. Using HTM cells as a model, the activation of α₂-ARs did not measurably affect AQP-1 messenger RNA or AQP-1 protein levels as compared to control. However, since the α₂-ARs primarily couple to cyclic AMP (cAMP) and several other aquaporins are regulated by cAMP, the effect of cAMP on AQP-1 was investigated. Using Xenopus oocytes expressing AQP-1 as a model, stimulation of oocytes with forskolin, a drug which increases intracellular cAMP, increased the permeability of AQP-1 to water. This observation provided evidence that is consistent with the general hypothesis that AQP-1 water channels and α₂-ARs are functionally coupled.

Several glucagon analogues containing substitutions in the N-terminal region, in particular residues 1, 5, 6, 9 and 10 (histidine, threonine, phenylalanine, aspartic acid and tyrosine, respectively), were synthesized. In addition four β-methylphenylalanine isomers were introduced at position ten to assess the role of these topographical modifications on hormone activity, and to study the effect of constraint and biased conformational preferences of the side chain moieties on biological activity. All the analogues were synthesized by solid-phase methodology, purified to homogeneity by reverse-phase high-performance liquid chromatography, and characterized by electrospray mass spectroscopy, amino acid analysis and thin layer chromatography. Following characterization they were analyzed using rat liver plasma membranes for receptor-binding affinity as well as their ability to stimulate adenylate cyclase. Structure-activity relationship analysis provided critical information about the conformational, chemical and structural properties of amino acid residues required for receptor recognition and signal transduction in the glucagon sequence. His¹ was confirmed to operate along with Asp⁹ for the activation and binding to the glucagon receptor. These new findings should permit the design of more pure and potent glucagon receptor antagonists by focusing on the role of Phe⁶ and other residues in the N-terminal region. A newly developed assay for examining low levels of cAMP accumulation in response to glucagon antagonists, agonists and partial agonists was developed. Previously reported glucagon receptor antagonists had partial agonist activity in rat hepatocytes. This assay system, in conjunction with binding and adenylate cyclase studies in both hepatocytes and liver plasma membranes, redefines the major characteristics of pure glucagon antagonists. The most potent glucagon receptor antagonist [des-His¹, des-Phe⁶, Glu⁹]glucagon-NH₂ was studied using conformational analysis and 2D NMR techniques to analyze the secondary structure of the analogue. Proton resonance assignments using COSY, NOESY and TOCSY in d₆-DMSO were made.

DHEA (dehydroepiandrosterone) is a major adrenal hormone, with known accepted function. In both animals and humans low DHEA and DHEA-sulfate levels are associated with a number of problems in the aging: immunosenescence, increased mortality, increased incidence of several cancers, loss of sleep, decreased feelings of well-being, osteoporosis, atherosclerosis and premature death. DHEA hormone replacement in aged mice significantly normalized immunosenescence suggesting that this hormone plays a key role in aging and stimulating immune regulation in mice. Similarly osteoclasts and lymphoid cells, were stimulated by DHEA replacement which should delay osteoporosis. Recent studies do not support the original suggestion that low serum DHEA levels were associated with Alzheimer's and other losses of mental function in aged people. As DHEA modulates energy metabolism low levels should affect lipogenesis and gluconeogenesis, increasing the risk of diabetes and heart disease. Most of the actions of DHEA restoration are hypothesized from epidemiological or animal model studies and need to be tested in human trials. Those conducted in humans show essentially no toxicity of DHEA treatment at levels restoring serum DHEAS levels without evidence of altering some aging physiological systems. Thus DHEA is a steroid whose deficiency could facilitate development of some diseases common to the aged. Dehydroepiandrosterone (DHEA) and DHEA-sulfate (DHEAS) are steroids, synthesized from cholesterol (Fig. 1.1). While DHEA is secreted primarily by the adrenal gland in larger quantities than any other adrenal steroid including cortisol, the precise functions of DHEA and DHEAS in humans are not known (1-5). The decline of DHEAS levels during aging is parallel to development of immunosensecence, an inability to conserve protein, a physical frailty, decreased muscle mass, an increased fat mass, decreased ability to cope, disrupted sleep patterns and increased incidence of disease. Thus DHEAS serves as a marker of aging in humans. While the precise biological functions of DHEA and DHEAS are not known, both animal and human studies suggest some hypotheses while dispelling others. Therefore key physiological dysfunctions are investigated here to determine biological relationships which participate in the declining blood levels of DHEA with age.

The consensus view is that cardiac hypertrophy is an adaptive response to increased work caused by a variety of stimuli. While hypertrophy can be defined as an increase in cell mass without an increase in cell number, not all increases are equivalent in type and amount of protein accumulated. Our goal in this study was to identify the common steps in the process of cardiac hypertrophy. Our working hypothesis was that in all forms of cardiac hypertrophy glucose utilization increases and that the percentage of energy derived from fatty-acid oxidation decreases. The first part of this study entailed the development and characterization of a neonatal rat heart cell model. The model had to provide uniform culture conditions for rapid development of hypertrophy by agents acting at different sites in the cardiomyocytes. The second part of this study was composed of an assessment of hypertrophy caused by four pharmacologically distinct agents: norepinephrine, angiotensin-II, endothelin-I and tetradecylglycidic acid. In this part we compared the quantity of protein accumulation and quality of hypertrophy cause by each agent. This task was accomplished by examining the effect of each agent on selected mRNA messages and alteration in DNA content of cardiomyocytes. Here we also examined the effect of protein kinase-C, endothelin-I and angiotensin-II inhibitors on hypertrophy caused by each agent. In the final part of this study, metabolic alteration in hypertrophy caused by each agent was assessed for a potential common pathway to hypertrophy. As part of this analysis, we examined changes in glucose and palmitate oxidation, glucose uptake and role of pentose pathway in hypertrophy resulting from treatment of cardiomyocyte by each agent.

Osteoporosis is a condition of reduced bone mineral density (BMD) resulting in an increased susceptibility to bone fractures. The purpose of this study was to determine the effects of 12 months of weight bearing and resistance exercise on BMD, bone formation, measured by serum osteocalcin (OC) and bone resorption, measured by urinary excretion of deoxypyridinoline crosslinks (Dpd), in 2 groups of postmenopausal women who were either taking or not taking hormone replacement therapy (HRT). Secondary aims were to characterize the changes in insulin-like growth factors-l and -2 (IGF-l and -2) and IGF binding protein 3 (IGFBP3) in response to exercise training, and to determine the contribution of these growth factors in predicting changes in bone mineral density in the 2 populations of postmenopausal women. Women who were three to ten years postmenopausal and aged 40-65 years were included in the study. Women in HRT and no HRT groups were randomized into the exercise intervention resulting in four groups: (1) women not taking HRT, not exercising; (2) women taking HRT, not exercising; (3) women exercising, not taking HRT; and (4) women exercising, taking HRT. The number of subjects per group after one year was 27, 21, 25, and 16, respectively. Exercise training and HRT increase BMD similarly at most BMD sites whereas the combination of exercise and HRT produced increases in BMD greater than either treatment alone. Bone remodeling was surpressed in the groups taking HRT regardless of exercise status. The bone remodeling response to exercise training in women not taking HRT was not significantly different from those not exercising but the direction of change suggests an elevation in bone remodeling in response to exercise training. Exercise training does not stimulate a change in IGF-1, IGF-2, IGF-1:IGF-2, and IGFBP3. Markers of bone remodeling and IGF-1 are significant predictors of BMD changes but the overall amount of variation in BMD changes accounted for is low. Exercise and HRT status were significant predictors of changes in BMD even after accounting for variation due to bone remodeling indicating that bone changes are regulated by factors not addressed in this study.

One concept central to theories of multijoint control concerns the selection of muscles for the appropriate joint motion. For multijoint movements, a given muscle torque at an individual joint can lead to flexion, extension, or very little motion, since mechanical effects coming from other segments interact with muscle torque. This study quantified the contribution of muscle torque to initial joint motion for horizontal arm movements throughout the workspace. Previous studies of arm mechanics have been limited to a few movements or have focused on one joint. In contrast, this study reports data for both the shoulder and elbow joints. Moreover, a large number of movements were used for which direction, excursion, and distance were manipulated. Using high speed video recordings and techniques of inverse dynamics, a ratio of muscle torque to total torque was computed for each movement as a measure of contribution of muscle torque to joint acceleration. One consistent finding was that the muscle torque contribution consistently differed between the shoulder and elbow for most of the workspace. At one joint, muscle torque directly contributed to acceleration with negligible interaction torque ('direct' muscle torque contribution), thus the joint appeared to act as the launcher of the arm. At the other joint, both muscle and interaction torques contributed to joint acceleration ('complex' contribution), thus the joint appeared to be responding to mechanical effects from motion of the launcher. This contrast between joints may provide a simplifying feature for multijoint arm control. Specifically, only one of the two joints has complex mechanics, while the other joint, surprisingly, has simplified mechanics similar to a single joint in isolation. Movements in this study also demonstrated a three fold covariance (muscle torque contribution, movement direction, and the relative excursions of the shoulder and elbow) regardless of distance. A covariance of movement features, historically viewed as a confound, may provide a further simplification for arm control by reducing the unknowns; namely, the muscle torque contribution is associated with a resultant direction and joint excursions, or a direction or set of excursions is achieved by the associated muscle torque contribution.

Each year in the United States five percent of the over 2.5 million women living with breast cancer will have a recurrence. The possibility that dietary change may increase breast cancer-free survival is currently under investigation. Three mechanisms by which diet may have an effect include: (1) improved immunity, (2) reduced oxidative DNA damage and (3) reduced body weight and fat. The hypothesis of this dietary intervention study was that women previously treated for breast cancer who adhere to a diet high in fruit, vegetables and fiber and low in fat would demonstrate improved immune function, reduced oxidative DNA damage and reduced body weight and fat as compared to women assigned to the control diet. Seventy-seven women treated for Stage I, II or IIIA breast cancer were enrolled in this clinical trial. Sixty-six completed the six month intervention. The average participant was caucasian, educated, postmenopausal and 52 years of age. At the end of six months the intervention the diet group showed significantly higher natural killer cell (NKC) lysis at an effector to target cell (E:T) ratio of 100:1. Lytic units were not significantly different. Diet was not associated with immune function except for beta-carotene intake which was associated with greater changes in the percentage of NKCs in the intervention group. Oxidative DNA damage was significantly lower among participants in the intervention diet group at the end of the study. Oxidative DNA damage was inversely associated with intake of vegetables, fruit and micronutrients thereof and positively associated with dietary fat, saturated fat and meat intake. No significant differences in body weight or fat were identified; however, both groups showed a significant decrease in body fat of 1.0%. In conclusion, the dietary intervention was able to produce significant changes in nutrient intake, a significant increase in NKC activity at an E:T ratio of 100:1 but not other immune markers, and significant reductions in oxidative DNA damage among breast cancer survivors. The role of NKC immunity and reduced DNA damage in relationship to breast cancer recurrence remains to be determined. A longer term, larger study should provide the answer.