Thesis (Ph.D.)--University of California, San Francisco, 2009. / Source: Dissertation Abstracts International, Volume: 71-02, Section: B, page: . Adviser: Keith R. Yamamoto.

<p> In the present study, a form of endocrine disruption that impacts production of the important stress and metabolic hormone, cortisol, was confirmed in southern California English sole (<i>Parophrys vetulus</i>) and further characterized using cellular and molecular approaches. One of the key initial findings of the study was that the interrenal itself, when tested directly for its <i>in vitro</i> response to pituitary ACTH, was non-responsive in fish exhibiting the endocrine-disrupted phenotype. This pointed directly to a dysfunctional interrenal gland in the impacted fish. With this knowledge in hand, a proteomics-based approach was employed to screen for changes in tissue protein expression. This experimental effort resulted in the molecular identification of 107 proteins, 83 of which were from unique genes, and it elucidated a variety of changes in protein expression related to interrenal function and to exposure of the fish to specific kinds of anthropogenic environmental chemicals.</p>

<p> Agrochemical exposure is one of the factors that contributes to worldwide amphibian declines. Most studies that examine agrochemicals and amphibian declines focus on toxicity. However, declines are more likely caused by the sub-lethal effects of agrochemical exposure. Past emphases on the lethal effects of agrochemical exposure have overshadowed the contribution of decreased recruitment in amphibian declines. Additionally, studies that examine agrochemicals and reproductive function tend to focus on the effects of single chemical exposures instead of the effects of ecologically relevant mixtures. To address these issues, this dissertation examined the effects of ecologically relevant agrochemical exposures on the stress response and the reproductive endocrinology, morphology, and behaviors of male amphibians in the laboratory and the wild. </p><p> Chapter 1 provides a general review of the factors implicated in amphibian declines and provides an overview of the previous research conducted on the effects of agrochemical exposure on recruitment. </p><p> Chapter 2 is a field study that examined whether agricultural run-off alters the stress response and reproductive function of male bullfrogs (<i> Lithobates catesbeianus</i>). Bullfrogs were collected upstream and downstream of agricultural activity across three California river systems (Salinas, Sacramento and San Joaquin). Size, primary and secondary sex traits, sperm count, and corticosterone and testosterone levels were examined. Overall, bullfrogs living downstream of agricultural activity (i.e. exposure to agricultural run-off) were small and had elevated testosterone and corticosterone levels. In addition, downstream males from the Salinas and San Joaquin Rivers were also small in size and had elevated testosterone levels. However, only downstream males of the San Joaquin River had elevated corticosterone and exaggerated secondary sex traits. Together, these data suggest that living downstream of agriculture can alter size, hormone levels, and the expression of sexually dimorphic sex traits. Such changes to the reproductive endocrinology and morphology of male amphibians can be detrimental to the reproductive health and long-term reproductive success of amphibian populations. </p><p> In Chapter 3, I examined corticosterone, testosterone, and the reproductive clasping behaviors of adult male African clawed frogs (Xenopus laevis) exposed to field collected and simulated agricultural run-off. This experiment implemented a novel eco-relevant experimental design to mimic real-life agrochemical exposures. Male frogs were exposed to field water collected downstream (agricultural run-off) and upstream (negative control) of agricultural activity along the Salinas River, CA. In addition, a pesticide mixture containing the top agrochemicals used in the Monterey County was included to simulate agricultural run-off. Mating behavior was suppressed in males exposed to simulated agricultural run-off but enhanced in males exposed to field collected agricultural run-off. In addition, testosterone levels of clasping males were elevated in comparison to controls. Males immersed in simulated agricultural run-off had significantly lower testosterone levels than control males in 2010. These data suggest that agrochemical exposure (both field collected and simulated) can alter reproductive hormones and clasping behaviors. Altered sex hormones and behaviors in male amphibians may play a role in amphibian declines. </p><p> Lastly, this dissertation is summarized in Chapter 4. The applicability of this dissertation as a model for amphibian declines and other reproductive related human health concerns are also introduced.</p>

<p> Previous studies find prenatal stress to relate to negative health in mothers and their children. Health behaviors such as exercise, proper nutrition, and relaxation have been found to reduce stress in non-pregnant populations, yet few studies have investigated the effect of these behaviors on prenatal stress. The current study examined the impact of exercise, nutrition, and relaxation on perceived stress, anxiety, and cortisol reactivity to a stress task in pregnant women. We hypothesized that women who exercised, had better eating habits, and engaged in relaxation would have reduced perceived stress, anxiety and more adaptive cortisol responses. Our results suggest an adaptive effect of exercise, and maladaptive effect of fat consumption on prenatal cortisol responses, but no association between health behaviors and perceived stress or anxiety. These findings contribute to our understanding of the relationship between health behaviors and stress during pregnancy, and may be useful for prenatal health interventions.</p>

<p>Aquatic environments adjacent to industrialized urban centers typically contain anthropogenic chemicals that may cause disruption of endocrine systems and physiological functions. This study investigated whether sites within San Francisco Bay are associated with endocrine disruption in the indigenous fish, shiner perch. The endocrine system that produces cortisol was tested, since it is critical for physiological regulation of stress response, metabolism, immune function and osmoregulation. The cortisol-producing tissue, the interrenal, was also investigated using proteomics technologies to initiate a process of identifying proteins with altered expression and which may therefore be involved in tissue dysfunction. Disrupted cortisol responses were detected in fish from several locations and they were related to certain kinds of contaminants and to changed expression of at least four interrenal proteins, which include heat shock protein 1, transferrin, calreticulin, and calmodulin. Several interrenal proteins were also newly identified. The approaches used herein have strong prospects as bioanalytical screening methodologies in environmental studies. </p>