Endocrinology Commons^™

Artificial Insemination And Fetal Programming In Beef Production Systems, Dempster M. Christenson

Department of Animal Science: Dissertations, Theses, and Student Research

Pregnancy to artificial insemination and late gestation fetal programming of the next calf crop are central to genetic development, reproductive longevity, calf crop productivity, and efficiency of cow/calf ranching. The purposes of this research are to find methods to improve pregnancy rate to artificial insemination, the growth and reproductive health of pregnant heifers, and the productivity of their offspring. In the first of four studies we found that extending the period of progesterone administration in an estrus synchronization protocol did not significantly hasten estrus response or increase pregnancy rate to artificial insemination, but timing of estrus within the melengestrol acetate …

Impact Of Short-Distance Road Transportation On Horse Health, Erica Jacquay

Theses and Dissertations--Veterinary Science

Horses are regularly transported across the United States; however, the reasons for travel, trip lengths, and management practices are not well characterized. While long distance transportation has been associated with increased incidences of health-related problems, the impact of short distance transportation on horse health is less understood. Notably, aged horses ( > 15 years) have an altered immune response following short-distance transportation, but this has yet to be compared to young horses. It is also unknown whether transportation stress would alter endocrine responses of horses with metabolic disorders, such as insulin dysregulation (ID) or pituitary pars intermedia dysfunction (PPID).

The objectives …

Puberty-Associated Changes In Kiss1r, Mc3r, And Mc4r In The Ewe, Ashleigh Caitlyn Thomson

Graduate Theses, Dissertations, and Problem Reports (ETD)

The neural mechanisms that control the onset of puberty are not completely understood. In livestock, the onset of puberty relies on an increase in gonadotropin releasing hormone (GnRH) and luteinizing hormone (LH). Kisspeptin, neurokinin B, and dynorphin neurons (KNDy) and their receptors, Kiss1r, NK3R, and KOR, respectively, are important regulators of puberty. Previous data from our laboratory has shown that KNDy neurons may be responding to other inputs, including the melanocortin system, that will affect the timing of puberty. Given this, we examined kisspeptin receptor (Kiss1r) mRNA expression in GnRH neurons as well as examining melanocortin 3 and 4 receptor …

Estradiol’S Role In Timely Puberty Onset In The Ewe, Eliana Gerardine Aerts

Graduate Theses, Dissertations, and Problem Reports (ETD)

In female sheep, the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus triggers luteinizing hormone (LH) to be released from the pituitary. Luteinizing hormone, in turn, acts on the ovaries to elicit estradiol (E₂) release. E₂ acts in a negative feedback manner to control the amount of LH released. The increase in LH release that drives puberty onset results from a decrease in sensitivity to E₂ as the animal ages. However, the neural mechanisms mediating this change in sensitivity are not known, as is where in the hypothalamus E₂-negative feedback occurs. In the arcuate …

Hypothalamic Manipulation Of The Anuran Hpg Axis: Alternative Hormones And A Non-Invasive Administration Route For Amphibian Assisted Reproductive Technologies (Art), Erin Michelle Saylor

Theses and Dissertations

Amidst the amphibian extinction crisis, in situ and ex situ amphibian species conservation initiatives utilize assisted reproductive technologies for optimal genetic management of captive and wild populations. Development of effective, simple, low-cost methods for obtaining gametes for artificial fertilization, sperm biobanking, or natural breeding alleviates obstacles for institutions or programs to apply reproductive technologies. Objectives herein include investigating the efficacy of alternative hormones for inducing spermiation, an alternative hormone administration route for inducing ovulation, exploring the physiological effects of hormone therapy, and utilizing sperm from deceased animals for biobanking.

Hormonal Control Of Osmoregulatory Proteins In The Intestine Of Atlantic Killifish (Fundulus Heteroclitus), Karma Hine

Biological Sciences Undergraduate Honors Theses

The Atlantic killifish (Fundulus heteroclitus) is a euryhaline fish, and thus able to maintain ionic and osmotic homeostasis in a wide range of salinities. When exposed to the dehydrating marine environment, the lost water is replenished through drinking seawater (SW) which is processed and absorbed in the intestine through the involvement of various cellular effectors. Intestinal water transport is osmotically driven by the active removal of NaCl from the gut lumen to the blood coupled to the precipitation of divalent Mg²⁺ and Ca²⁺ due to the secretion of bicarbonate. These processes allow for successive removal of …

Effects Of Social Context On Salivary Cortisol And Attention In Tufted Capuchins (Cebus [Sapajus] Apella), Andrew Desana

Master’s Theses

Social context alters cognitive performance, but the mechanisms for this remain unclear. One possibility is that stressors associated with social contexts mediate changes in cognitive performance by influencing attention. We conducted two experiments to investigate how social context affects performance on an attention task in capuchin monkeys (Cebus [Sapajus] apella). We additionally validated and measured physiological stress through salivary cortisol. In experiment one, capuchins were exposed to three conditions where they were either isolated or paired with an affiliative or agonistic social partner separated by a barrier. In experiment two, subjects received affiliative and agonistic conditions without barriers to allow …

Relationships Between Behavior, Energy Metabolites, And Corticosterone In Black-Legged Kittiwake (Rissa Tridactyla) Nestlings, Sierra Pete

Master’s Theses

Birds can cope with energy-shifting challenges by redirecting energy and behavior to maintain energetic homeostasis. Nestlings allocate energy to support their rapid growth and developmental period; thus, their challenges and the subsequent energetic demands can be much different than an adult. At a baseline level, energy is constantly shifting in response to regularly occurring challenges; however, more substantial challenges can initiate the production of glucocorticoid hormones. In birds, the main glucocorticoid is corticosterone. Corticosterone is believed to aid in energy homeostasis by redirecting energy metabolite mobilization. Energy metabolites are intermediaries or end products of cellular metabolism, thus, metabolites like glucose …

Increasing Efficiency Of Finishing Beef Production: Strategies To Optimize Starch Digestion, Improve Flake Quality, And Reduce Methane Emissions, Ronald J. Trotta

Theses and Dissertations--Animal and Food Sciences

To continue to meet the demands of increasing food production and environmental sustainability, new strategies are needed to enhance the efficiency of finishing cattle production. A review of the literature identified several nutritional and physiological constraints that limit the ability for cattle to digest starch and absorb glucose from the small intestine. Comparative sequencing analyses revealed a missing region of the sucrase-isomaltase protein which could affect the capacity for starch digestion in cattle. Post-flaking sampling and handling recommendations were generated based on a series of experiments to improve estimates of starch availability and flaking consistency for commercial feedlots and laboratories. …

A Multi-Species Study On Several Types Of Visitor Effects On The Behavior And Physiology Of Animals At The Oregon Zoo, Laurel Berylline Fink

Dissertations and Theses

The visitor effect on zoo animals is one of the expanding research topics in zoo animal research. As visitors are a mandatory feature of zoological institutions, understanding their effects on zoo animals is imperative for maximizing zoo animal welfare. Zoo animals are subject to many anthropogenic influences: visual, olfactory, and audible, for example. This dissertation investigates several of the effects of visitor presence and its relative influence on six mammalian species: cheetahs (Acinonyx jubatus), African painted dogs (Lycaon pictus), Asian elephants (Elephas maximus indicus & Elephas maximus borneensis), giraffes (Giraffa camelopardalis reticulata & …

Effects Of Sunrise/Sunset Lighting On Corticosterone Levels In Coturnix Quail (Coturnix Coturnix), Hannah Feuerborn

Poultry Science Undergraduate Honors Theses

Both genetics and environment play an important role in the growth, performance and overall welfare of poultry species. Current commercial production practices typically do not mimic the natural environmental conditions of ancestral poultry species, specifically lighting requirements. In nature, poultry species are subjected to natural day length and the slow rising and setting of the sun. This is compared to commercial conditions in which lights are sudden on/off, not mimicking the natural trajectory of the sun in terms of light intensity and exposure. The current study aimed to evaluate the impact of genetics and the effect of sunrise/sunset lighting on …

Effects Of Sunrise/Sunset Lighting On Corticosterone Levels In Coturnix Quail (Coturnix Coturnix), Hannah M. Feuerborn, Sara K. Orlowski

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

Both genetics and environment play important roles in the growth, performance, and overall welfare of poultry species. Current commercial production practices typically do not mimic the natural environmental conditions of ancestral poultry species, specifically lighting. The current study aimed to evaluate the impact of genetics and the effect of sunrise/sunset lighting on the stress response of 4 genetic lines of Coturnix quail. The 4 lines utilized in this study included high stress (H), low stress (L), stress control (R), and Arkansas randombred (A) quail lines. Day old chicks from these lines were placed in one of two environmentally controlled rooms. …

Fertility Control Options For Management Of Free-Roaming Horse Populations, Ursula S. Bechert, John W. Turner Jr., Dan L. Baker, Douglas C. Eckery, Jason E. Bruemmer, Candace C. Lyman, Tulio M. Prado, Sarah R. B. King, Mark A. Fraker

Human–Wildlife Interactions

The management of free-roaming horses (Equus ferus) and burros (E. asinus) in the United States has been referred to as a “wicked problem” because, although there are population control options, societal values will ultimately determine what is acceptable and what is not. In the United States, free-roaming equids are managed by different types of organizations and agencies, and the landscapes that these animals inhabit vary widely in terms of access, size, topography, climate, natural resources, flora, and fauna. This landscape diversity, coupled with contemporary socioeconomic and political environments, means that adaptive management practices are needed to …

Estrogen Regulation Of Daily Metabolic Rhythms In Female Mice, Oluwabukola Omotola

Theses and Dissertations--Biology

Circadian rhythms are approximately 24-hour cycles of behavior, physiology, and gene expression. In mammals, these circadian rhythms are generated by clocks located in nearly every tissue in the body. The function of circadian clocks is to synchronize physiology and behavior with environmental cycles such as the light-dark cycle. After menopause, when circulating levels of estrogens are very low, women are more susceptible to obesity comorbidities such as metabolic syndrome and cardiovascular disease, suggesting that estrogens regulate these processes. Estrogens could protect females from metabolic dysfunction by regulating circadian rhythms. Consumption of diets that are high in fat contribute to obesity. …

Effects Of Melatonin Implantation On The Activity Levels Of Captive Snow Buntings (Plectrophenax Nivalis), Zoë Ward

Mahurin Honors College Capstone Experience/Thesis Projects

In vertebrates, melatonin regulates many components of the circadian rhythm; depending on the organism’s location and time of year, the pineal gland will produce melatonin accordingly, controlling the sleep-wake cycle and breeding physiologies. However, locations at the poles in which the sun is above the horizon for multiple days at a time pose unique challenges for the organisms living there. The goal of this study was to examine how the implantation of melatonin in an arctic-breeding songbird affects its activity levels and circadian rhythm. The subject of this study, the snow bunting (Plectrophenax nivalis), is a small songbird …

James Davidson Fawcett (1933–2020): Imbibing With The Kiwi, Louis A. Somma

Papers in Herpetology

An obituary and summary of the life of James D. Fawcett (1933-2020), herpetologist and instructor and professor of Biology at University of Nebraska at Omaha, 1972-2015. Includes bibliography of his works, list of master's theses chaired, and recollections of former students.

Morph- And Sex-Specific Differences In Corticosterone Of The Arizona Tiger Salamander (Ambystoma Mavortium Nebulosum), Megan Zerger

Scholars Week

Life history morph, sex, and body condition are traits that may influence stress within salamander populations because of differences in physiology and environmental conditions. Given widespread declines and the effects chronic stress can have on amphibian health, it is important to understand within-population drivers of stress and how population level variation may influence population viability. Thus, the objective of our study was to assess how corticosterone varies within the Arizona tiger salamander (Ambystoma mavortium nebulosum) population at the Mexican Cut Nature Preserve. We used a non-invasive skin swabbing method to collect baseline and elevated corticosterone from paedomorph (aquatic …

Sexually Dimorphic Oxytocin Receptor-Expressing Neurons In The Anteroventral Periventricular Nucleus Regulates Maternal Behavior, Kaustubh Sharma

LSU Doctoral Dissertations

The neurohypophysial hormone oxytocin is involved in the regulation of social behaviors, including social recognition, pair bonding, and sex-specific parental behaviors in a variety of species. Oxytocin triggers these social behaviors by binding to oxytocin receptors (OXTR) in various parts of the brain. Oxytocin-induced sex-typical behavior, therefore, suggests a sexual dimorphic distribution of OXTR in the brain. In recent years, the oxytocin system in the brain received tremendous attention as a potential pharmacological target for treatment of many psychiatric disorders, such as anxiety, autism spectrum disorders, and even sex-specific psychiatric disorder like postpartum depression (PPD). An important problem and a …

Non-Invasive Method For Leptin Supplementation In Zebrafish (Danio Rerio), Regan Mcnamara

Williams Honors College, Honors Research Projects

I tested the hypothesis that recombinant leptin protein can be introduced to zebrafish in vivo through non-invasive soaking in a solution containing the protein. One way to study various molecules’ effects in vivo is through intraperitoneal or intracerebroventricular injections during the embryonic or larval stage, which is invasive, difficult to administer, and can have a high mortality rate. 48 hours post fertilization (hpf) zebrafish were soaked in a His-tagged recombinant leptin protein solution at 10 nM and 100 nM concentrations (produced by Genscript). After soaking, zebrafish larvae were washed extensively to remove all recombinant protein on their exterior before homogenization. …

Stress And Body Composition Of Juvenile Alligator Snapping Turtles (Macrochelys Temminckii), Brandon Scott Tappmeyer

Graduate Theses/Dissertations

The alligator snapping turtle (Macrochelys temminckii), is a species of conservation concern that is the subject of multiple head-start and reintroduction efforts across its range. In captive propagation programs, producing offspring that are in optimal physiological condition maximizes the likelihood of success after release. The purpose of my study was to compare stress and body composition between one free-ranging reintroduced population and two captive populations. The two captive populations were both housed in southern Oklahoma, but one group was reared indoors whereas the other inhabited outdoor ponds at a national fish hatchery. I used circulating glucocorticoid (corticosterone) concentrations as an …

Responses Of Bovine Pituitary Transcriptome Profiles To Consumption Of Toxic Tall Fescue And Forms Of Selenium In Vitamin-Mineral Mixes, Qing Li

Theses and Dissertations--Animal and Food Sciences

The first goal of the current research was to determine whether gene expression profiles differed between whole pituitaries of growing beef steers grazing pastures containing high (HE) or low (LE) amounts of toxic endophyte-infected tall fescue. The global (microarray analysis) and selected targeted (RT-PCR) mRNA expression patterns of pituitaries collected from beef steers (BW = 266 ± 15.5 kg) that had been randomly assigned to undergo summer-long grazing (89 to 105 d) of either HE (0.52 ppm ergot alkaloids) or LE (< 0.03 ppm ergot alkaloids) pastures were compared. Gene expression data were subjected to one-way ANOVA. The pituitaries of HE steers had 542 differentially expressed genes, and the pattern of altered gene expression was dependent on treatment. Targeted RT-PCR analysis corroborated these findings, including decreased expression of DRD2, PRL, POU1F1, GAL, and VIP and that of POMC and PCSK1, respectively. Canonical pathway analysis (Integrated Pathway Analysis, IPA) identified HE-dependent alteration in signaling of additional pituitary-derived hormones, including growth hormone and GnRH. In conclusion, consumption of endophyte-infected tall fescue alters the pituitary transcriptome profiles of steers in a manner consistent with their negatively affected physiological parameters. The second goal of this project was to test the hypothesis that sodium selenite (ISe), SEL-PLEX (OSe), vs. a 1:1 blend (MIX) of ISe and OSe in a basal vitamin-mineral (VM) mix would differentially alter pituitary transcriptome profiles in growing beef steers (BW = 183 ± 34 kg) commonly grazing an endophyte-infected tall fescue (HE) pasture. Steers were randomly selected from herds of fall-calving cows grazing HE pasture and consuming VM mixes that contained 35 ppm Se as either ISe, OSe, or MIX forms. Steers were weaned, depleted of Se for 98 d, and subjected to summer-long common grazing of a 10.1 ha HE pasture containing 0.51 ppm ergot alkaloids. Steers were assigned (n = 8) to the same Se-form treatments on which they were raised. Selenium treatments were administered by daily top-dressing 85 g of VM mix onto 0.23 kg soyhulls, using in-pasture Calan gates. Pituitaries were collected at slaughter and changes in global (microarray) and selected (RT-PCR) mRNA expression patterns determined. The effects of Se treatment on relative gene expression were subjected to one-way ANOVA. The form of Se affected the expression of 542 annotated genes. Integrated Pathway Analysis found a canonical pathway network between prolactin and POMC/ACTH/ α-MSH synthesis-related proteins, and that mitochondrial dysfunction was a top-affected canonical pathway. Targeted RT-PCR analysis found that the relative abundance of mRNA encoding prolactin and POMC/ACTH/ α-MSH synthesis-related proteins was affected by the form of Se, as were mitochondrial dysfunction-related proteins OSe steers appeared to have a greater prolactin synthesis capacity vs. ISe steers through decreased dopamine receptor D2 signaling, whereas MIX steers had a greater prolactin synthesis capacity and release potential by increasing TRH concentrations than ISe steers. OSe steers also had a greater ACTH and α-MSH synthesis potential than ISe steers. We conclude that form of Se in VM mixes affected genes responsible for prolactin and POMC/ACTH/α-MSH synthesis, and mitochondrial function in pituitaries of growing beef steers commonly grazing an HE pasture. The third goal was to test the hypothesis that sodium selenite (ISe), SEL-PLEX (OSe), vs. a 1:1 blend (MIX) of ISe and OSe in a basal vitamin-mineral (VM) mix would differentially alter selenoprotein profiles in pituitaries and livers of growing beef steers commonly grazing an endophyte-infected tall fescue (HE) pasture (i.e., the same steers used in Goal 2). The effects of Se treatment on relative gene expression were subjected to one-way ANOVA. The mRNA content of 6 selenoproteins in the pituitary was affected by Se treatments, along with two selenoprotein P receptors, whereas the expression of two selenoproteins was altered in the liver. We conclude that the change in selenoprotein gene expression in pituitaries indicates that OSe steers have a greater potential capacity to manage against oxidative damage, maintain cellular redox balance, and have a better quality control of protein-folding in their pituitaries than ISe steers. The change in selenoprotein gene expression by the liver indicates that MIX steers have a greater redox signaling capacity and capacity to manage oxidative damage than ISe steers.

Population Health Of Spotted Salamanders (Ambystoma Maculatum) In Created Vernal Pools: An Integrative Approach, Alice R. Millikin

Graduate Theses, Dissertations, and Problem Reports (ETD)

Habitat creation is an important tool for conservation to counteract habitat loss and degradation. Vernal pools are susceptible to destruction due to limited detection, protection, and regulation. These wetlands provide fishless breeding habitat for many amphibian species including spotted salamanders (Ambystoma maculatum) in eastern North America. Determining whether created vernal pool habitat is successful is often determined by demographic data of colonizing populations. I suggest that hormone levels, population genetics, and disease prevalence can improve our understanding of population health in created habitat. The goal of this dissertation was to assess the health of spotted salamander larvae in …

Of Course, Humans Are Not Unique!, Bernard Wallner

Animal Sentience

This commentary focuses on the question of the uniqueness of humans in comparison to other species and on the false assumption that single arguments support logical conclusions. Comparative analysis of genetic data in humans and nonhuman primates regarding the dopaminergic system of the subcortical mesolimbic reward system highlights homologous traits shared and modified by the process of evolution. Such an analytical approach is more relevant than claims of uniqueness.

The Impact Of Insulin Dysregulation On Protein Metabolism In Horses, Caroline Margot Marcelle Loos

Theses and Dissertations--Animal and Food Sciences

Insulin plays a vital role in whole-body metabolism and provides a major anabolic stimulus for cellular signaling pathways, including those involved in the metabolism of glucose and protein. Consequently, insulin dysregulation (ID) is known to alter molecular signal transduction in insulin-sensitive tissues such as skeletal muscle, thereby disrupting glucose metabolism and compromising protein synthetic capacity. Our first objective was to induce ID in healthy horses by administering dexamethasone (DEX), a potent glucocorticoid, for 21 days. We evaluated the effects on insulin-stimulated muscle protein signaling components involved in the mammalian target of rapamycin (mTOR) pathway. DEX-induced ID reduced insulin-stimulated activation of …

Consequences Of Porcine Zona Pellucida Immunocontraception To Feral Horses, Cassandra M.V. Nuñez

Human–Wildlife Interactions

Porcine zona pellucida (PZP) immunocontraception was developed to provide a more humane, effective, and inexpensive method of population regulation for wildlife species. It has been used to regulate populations of several species including white tailed deer (Odocoileus virginianus), elk (Cervus elaphus ), black bear (Ursus americanus ), and the feral horse (Equus ferus caballus) with varying levels of success. Early studies on Assateague Island National Seashore, Maryland, USA, suggested PZP was as an ideal form of fertility control because it reduced the likelihood of conception to

Organizational Effects Of Defeminizing Toxicants: Lessons Learned From An Environmental Sentinel Organism, The Fathead Minnow., Jonathan Ali

Theses & Dissertations

Endocrine disrupting compounds (EDCs) are chemicals that interfere with hormone function and are increasingly detected in aquatic environments, where they elicit adverse effects from exposed organisms. The toxicological effects of EDCs can be described as either activational (reversible) or organizational (irreversible), where the latter are associated with adverse outcomes in reproductive performance of adult fish. However, few studies have investigated the organizational impacts of anti-estrogenic or “defeminizing” EDCs, e.g. agrichemicals or pharmacological agents, in an environmentally-relevant or “sentinel” species. The objective of this study was to investigate the impacts of early-life EDC-initiated changes in estrogenic gene expression on organizational effects …

The Impact Of Various Predator Perceptions On Stress Response And Spatial Memory In Birds, Chlöe S. N. Carter

Western Research Forum

The Impact of Various Predator Perceptions on Stress Response and Spatial Memory in Birds

Background

This project will explore the impact of environmental stressors on the cognitive abilities of birds. Predator perception has been demonstrated to elicit a stress response by elevating stress hormones which can alter the behaviour of birds. The aim of this study is to observe if chronic stress from differently perceived threats of predation in an individual’s environment will lead to differences in the spatial memory abilities in two species of birds. I predict that chronic stress resulting from predator stimuli will impair the bird’s performance …

Effects Of Sleep Fragmentation On The Immune System Of Zebra Finches Using Cytokine Gene Expression, Laken N. Cooper

Masters Theses & Specialist Projects

Sleep loss is known to trigger an inflammatory response and increase serum corticosterone in both human and murine models. However, very little evidence is available on the potential effects of sleep loss in avian models. This study aims to construct a profile using cytokine gene expression data to determine how birds respond to sleep loss in a controlled environment. I investigated changes in pro-inflammatory (IL-1β and IL-6) and anti-inflammatory (IL-10) cytokine gene expression in the periphery (fat, liver, spleen, and heart) and brain (hypothalamus, hippocampus, and apical hyperpallium) in zebra finches exposed to a novel sleep fragmentation method. Serum corticosterone, …

Cross-Sectional Analysis Of Salivary Cortisol And Cyathostome Infestation In Horses, Danielle L. Keating

Undergraduate Honors Thesis Projects

With an increase in anthelmintic resistance and decreased efficacy of many commercial dewormers, understanding factors that contribute to parasite infestations in horses is integral to their management. The goal of this study was to look at the potential relationship between parasites and stress response by evaluating salivary cortisol levels and cyathostome egg shedding levels. Using a sample size of n = 200 horses from the state of Ohio, fecal and saliva samples were collected from each horse. Fecal egg counts were performed for each horse with a modified Stoll method, and saliva samples were tested with an enzyme-linked immunosorbent assay …

Lh-Independent Testosterone Secretion Is Mediated By The Interaction Between Gnrh2 And Its Receptor Within Porcine Testes, Amy T. Desaulniers, Rebecca A. Cederberg, Ginger A. Mills, J. Joe Ford, Clay A. Lents, Brett R. White

Department of Animal Science: Faculty Publications

Unlike classic gonadotropin-releasing hormone 1 (GNRH1), the second mammalian isoform (GNRH2) is an ineffective stimulant of gonadotropin release. Species that produce GNRH2 may not maintain a functional GNRH2 receptor (GNRHR2) due to coding errors. A full-length GNRHR2 gene has been identified in swine, but its role in reproduction requires further elucidation. Our objective was to examine the role of GNRH2 and GNRHR2 in testicular function of boars. We discovered that GNRH2 levels were higher in the testis than in the anterior pituitary gland or hypothalamus, corresponding to greater GNRHR2 abundance in the testis versus the anterior pituitary gland. Moreover, GNRH2 …