Life Sciences Commons^™

Associations Between Early Childhood Sleep, Memory Function, And Brain Development Across The Nap Transition, Sanna Lokhandwala

Doctoral Dissertations

Preschool-age children often distribute their sleep across a midday nap and overnight sleep. Skipping the nap is suggested to increase the duration and depth of deep sleep (i.e., slow wave activity; SWA). Moreover, missing the midday nap has been shown to impair learning processes. This may be because children’s brains at this point in development are immature, necessitating the intervening nap period to strengthen memories before they are forgotten. Nonetheless, at some point during the preschool years, many children begin transitioning naturally out of napping. It is unclear whether the memory benefits of overnight SWA after a skipped nap depend …

Osmoregulation And Appetite Regulation In A Basal Vertebrate, The Sea Lamprey (Petromyzon Marinus), Jessica Norstog

Doctoral Dissertations

Lamprey (Petromyontiformes) are the oldest extant family in the vertebrate lineage, providing a unique phylogenetic position for studies on vertebrate evolution. As a basal vertebrate, sea lamprey (Petromyzon marinus) is an important species to understand evolution and comparative physiological mechanisms, including osmoregulation and appetite regulation. Sea lamprey has anadromous (native to the Atlantic Ocean) and landlocked (invasive in the Laurentian Great Lakes in North America) populations. In both populations of sea lamprey, the blind filter-feeding freshwater (FW) larvae burrow in stream sediments for until undergoing a hormonal-driven metamorphosis. During this phase, sea lamprey do not feed as major …

Role Of Fat Content On The Structure And Function Of Human Skeletal Muscle, Joseph A. Gordon Iii

Doctoral Dissertations

Muscle size does not fully explain variations in muscle strength. Fat content has been implicated in muscle weakness, though this relationship remains unclear. The relationship between fat and strength may vary between scales (e.g., cellular, organ, and organism). The goal of this dissertation was to clarify the role of fat in the structure and function of muscle using in vitro and in vivo techniques across multiple scales in adults 21-45 years old. Study 1 tested the agreement of intramyocellular lipid (IMCL) content between oil red o (ORO) and magnetic resonance spectroscopy (MRS) techniques. These measures of IMCL were also compared …

Beyond The Fat: Protein Metabolism And Muscle Function As Part Of The Migratory Syndrome Of Songbirds, Cory R. Elowe

Doctoral Dissertations

Migration allows animals to seasonally exploit favorable habitats that are geographically disparate, and migratory animals have a suite of adaptations to complete their extraordinary journeys. This “migratory syndrome” of traits is comprised of seasonally-responsive adaptations that together result in changes to metabolism, body composition, and reproductive status, all of which act to increase the probability of a successful migration. The focus of my dissertation is to investigate the suite of changes in metabolism and muscle function that enable birds to undertake long-duration flights. In chapter 1, I compare fuel use in flight between two related migratory warbler species that migrate …

Frontiers In The Self-Assembly Of Charged Macromolecules, Khatcher O. Margossian

Doctoral Dissertations

The self-assembly of charged macromolecules forms the basis of all life on earth. From the synthesis and replication of nucleic acids, to the association of DNA to chromatin, to the targeting of RNA to various cellular compartments, to the astonishingly consistent folding of proteins, all life depends on the physics of the organization and dynamics of charged polymers. In this dissertation, I address several of the newest challenges in the assembly of these types of materials. First, I describe the exciting new physics of the complexation between polyzwitterions and polyelectrolytes. These materials open new questions and possibilities within the context …

Flexible Phenotypes, Energetics, And Whole-Animal Performance Of Migratory Songbirds, Michael Griego

Doctoral Dissertations

Animal life has evolved innumerable strategies to adapt to a great range of environmental conditions present on earth. The physiology of free-living animals has thus been shaped to allow for maximal performance under challenging conditions and has given rise to traits that enable animals to overcome daunting ecological pressures. Few life history stages in the animal kingdom rival the intensity of annual avian migration: the extreme metabolic requirements of long-distance flight coupled with navigating vast and hostile ecological barriers results in enormously high mortality for young birds. It is therefore the main focus of this thesis to identify physiological traits …

Controlling Myosin’S Function Via Interactions Between The Substrate And The Active Site, Mike K. Woodward

Doctoral Dissertations

Molecular motors, such as myosin, have evolved to transduce chemical energy from ATP into mechanical work to drive essential cellular processes, from muscle contraction to vesicular transport. Dysfunction in these motors is a root cause of many pathologies necessitating the application of intrinsic control over molecular motor function. We hypothesized that altering the myosin’s energy substrate via minor positional changes to the triphosphate portion of the molecule will allow us to control the protein and affect its in vitro function. We utilized positional isomers of a synthetic non-nucleoside triphosphate, azobenzene triphosphate, and assessed whether myosin’s force- and motion-generating capacity could …

A Study Of The Effect Of Physiological Stressors On Hypothalamic Regulation Of Reproduction Using An In Vitro System, Lisa L. Amelse

Doctoral Dissertations

Stressors have a negative impact on reproductive efficiency in humans and other animals, which has an economic cost due to infertility treatments for humans and reduced income for food producers. We wished to determine the molecular pathways by which metabolic disturbances and low-level inflammation impact the hypothalamic pituitary gonadal (HPG) axis using an in vitro model. To this end, we used the GT1-7 cell line, an immortalized line expressing the Kiss1R receptor that responds to kisspeptin stimulation with the release of GnRH to assess the impact of stressors on the GnRH-releasing cells. Additionally, we used the KTaV-3 and KTaR-1[A1] …

Thermal Ecophysiology Of Juvenile Anadromous River Herring, Lian W. Guo

Doctoral Dissertations

Temperature controls the rate of all biochemical processes, and thus can significantly influence the physiology and ecology of all living organisms on earth. Understanding how temperature influences fitness can therefore provide insight into mechanisms affecting population size, dynamics, and geographic distributions, especially in the context of climate change. Early life stages of fishes experience significant selective pressure to grow large and accumulate energy reserves in order to avoid predation and starvation. Increasing temperatures will increase routine metabolic rates, which may result in less energy being available for growth and energy storage. In this thesis, I examine the effects of temperature, …

The Neurobiological Underpinnings Of Depression-Related Maternal Behavior Deficits, Sarah B. Winokur

Doctoral Dissertations

Maternal caregiving is a dynamic process that requires extensive cognitive, motivational, and affective processing. World-wide, approximately 17% of mothers are diagnosed with postpartum depression yearly (Wang et al., 2021). Untreated, mothers with postpartum depression experience deficits in cognition, motivation, affect, and parenting (Arteche et al., 2011; Dix and Meunier, 2009; Lovejoy et al., 2000). Although postpartum depression is related to compromised parenting, to date, few studies have examined the neurobiological mechanisms by which maternal behavior is compromised in postpartum depression (Field, 2010; Murray et al., 1996)_. This dissertation aims to examine how depression neurobiologically disrupts parenting abilities. These studies …

Circadian Regulation Of The Timing Of Pre-Ovulatory Luteinizing Hormone Surge In Mice And Hamsters, Ajay Kumar

Doctoral Dissertations

Endogenous daily (circadian) oscillators ensure the proper timing of physiological and behavioral processes that are essential to health. A set of core clock genes and their protein products function in transcriptional/translational feedback loops (TTFLs) that time and coordinate vital homeostatic, cognitive, and hormonal processes. A master pacemaker in the suprachiasmatic nucleus (SCN) coordinates circadian function throughout the organism. Investigating the causal role of genetically defined cell types in the suprachiasmatic nucleus for circadian rhythms is essential to understand how an animal’s physiology is temporally organized. This thesis explores the role of molecular clocks within particular cell types in regulating physiology. …

Physiology Of A Basal Vertebrate, The Sea Lamprey (Petromyzon Marinus): Osmoregulation And Corticosteroid Action, Ciaran A. S. Shaughnessy

Doctoral Dissertations

Lamprey represent the most basal living example of a vertebrate animal which regulates its internal fluid and ion homeostasis. This phylogenetic position among vertebrates makes lamprey an important model organism for understanding the basal state, and thus the evolution, of physiological systems such as the mechanisms of osmo- and ionoregulation and the endocrine factors controlling them. Sea lamprey (Petromyzon marinus) are an anadromous fish, migrating from freshwater (FW) to seawater (SW) as juveniles, then returning back upstream as mature adults to spawn. Surviving this transition from a solute-poor FW environment to a solute-concentrated SW environment requires many changes …

How Do Adult Songbirds Learn New Sounds? Using Neuromodulators To Probe The Function Of The Auditory Association Cortex, Matheus Macedo-Lima

Doctoral Dissertations

The ability to associate sounds and outcomes is vital in the life history of many species. Animals constantly assess the soundscape for cues associated with threats, competitors, allies, mates or prey, and experience is crucial for those associations. For vocal learning species such as humans and songbirds, learning sounds (i.e. perception and association learning) is also the first step in the process of vocal learning. Auditory learning is thought to depend on high-order cortical brain structures, where sounds and meaning are bound. In songbirds, the caudomedial nidopallium (NCM) is part of the auditory association cortex and is known to be …

Mechanisms That Limit Oxidative Phosphorylation During High-Intensity Muscle Contractions In Vivo, Miles F. Bartlett

Doctoral Dissertations

Skeletal muscle oxidative capacity plays a critical role in human health and disease. Although current models of oxidative phosphorylation sufficiently describe skeletal muscle energetics during moderate-intensity contractions, much is still unknown about the mechanisms that control and limit oxidative phosphorylation during high-intensity contractions. In particular, the oxygen cost of force generation is augmented during exercise at workloads above the lactate threshold. Presently, it is unclear whether this augmentation in muscle oxygen consumption is driven by increased rates of oxidative ATP synthesis (ATP_OX) or by decreases in the efficiency of ATP_OX due to mitochondrial uncoupling. To address this …

Cardiovascular Disease Risk And Menopause: Effects Of Cardiorespiratory Fitness, Exercise, And Follicle Stimulating Hormone, Corinna Serviente

Doctoral Dissertations

Menopause is associated with adverse changes in cardiovascular disease risk factors. A reduction in estrogens is most commonly associated with changing cardiovascular disease risk; however, recent observations suggest that the increase in follicle stimulating hormone that accompanies menopause may also influence risk, potentially through its influence on lipid levels. The changes in cardiovascular disease risk factors may adversely affect endothelial cell function, a pre-clinical marker for cardiovascular disease. Whether cardiorespiratory fitness is protective of endothelial health in this population, thereby mitigating the changes in risk that accompany menopause, is unclear. This dissertation evaluated differences in endothelial health and endothelial responses …

Sleep, And Its Relation To Non-Motor Deficits In Patients With Cerebellar Ataxia, Akshata Sonni

Doctoral Dissertations

The cerebellum is a highly connected structure, and its involvement in sleep – which is a dynamic process that is modulated by a complex set of neural systems – can come about through a number of neural pathways. We conducted two studies aimed at furthering our understanding of cerebellar involvement in sleep behavior and physiology, as well as measuring the impact of poor sleep on mood and cognition in patients with cerebellar degeneration. First, by means of an online battery including measures of sleep and neuropsychiatric function, we collected data from 176 patients with cerebellar ataxia. We found strong evidence …

Long-Term Treatment With Insulin And Retinoic Acid Increased Glucose Usage In L6 Muscle Cells Via Glycogenesis, Matthew Ray Goff

Doctoral Dissertations

Skeletal muscle glucose metabolism can affect whole body glucose homeostasis significantly. Vitamin A (VA) plays a role in a number of physiological functions including glucose metabolism. However, its role in skeletal muscle glucose metabolism has not been well established. Insulin controls glucose metabolism in the skeletal muscle via the regulations of glucose uptake, glycogenesis, and glycolysis. We hypothesize that insulin and VA signaling pathways may converge to regulate glucose metabolism in skeletal muscle. Here, the effects of retinoic acid (RA) alone and in combination with insulin on glucose utilization in rat L6 muscle cells were studied. L6 cells were treated …

Molecular Mechanisms Underlying The Contralateral Repeated Bout Effect (Crbe) In Human Skeletal Muscle, Ling Xin

Doctoral Dissertations

Eccentric (muscle lengthening) exercise induces temporary muscle damage that can lead to long-term muscle adaptation, a process known as the repeated bout effect where subsequent exercise results in less damage. The existence of a contralateral repeated bout effect (CRBE) has been controversial. The primary goals of this study were to: 1) validate the existence of the CRBE; and 2) define the underlying molecular mechanisms. Thirty-six young men performed 100 maximal eccentric actions of the knee extensors using one leg (bout 1) and repeated the exercise with the contralateral leg five weeks later (bout 2). Vastus lateralis muscle biopsies were …

The Inflammatory Response To Acute Muscle Injury, Kevin O'Fallon

Doctoral Dissertations

The overall goal of this dissertation was to examine inflammatory and regenerative responses to acute skeletal muscle damage and to define molecular mediators of repair. Study I examined the effects of an oral anti-inflammatory supplement on exercise-induced muscle damage (EIMD) and systemic inflammation in a human model. Quercetin has been shown in animal and in vitro models to downregulate nuclear factor-kappa beta (NF-κB) nuclear transactivation and monocyte chemoattractant protein 1 (MCP-1) secretion, which regulate muscle regeneration and inflammatory signaling between muscle and immune cells after injury. Subjects ingested quercetin (N=15) or placebo (N=15) before and after performing 24 eccentric contractions …

Effects Of Leaflet Orientation And Root Morphology On Physiological Traits And Yield In Soybeans., Richard Dewayne Johnson

Doctoral Dissertations

Drought is the most important abiotic stress adversely affecting soybean (Glycine max (L.) Merr.) yield. Leaflet orientation has been shown to reduce leaflet temperatures and transpiration while root morphology has been related to slower wilting phenotypes. The objective of this study was to investigate effects of leaflet orientation and rooting morphology on whole plant transpiration, yield, water use efficiency, and other physiological traits in soybeans using grafting techniques, population lines, near-isogenic lines, and restrained leaf canopy experiments. Experiments were conducted in Knoxville, TN with additional yield trial plots at Springfield, Spring Hill, and Milan, TN. Data were collected on …

Genetic And Nutritional Studies To Elucidate The Role Of Adipose Tissue In The Pathogenesis Of Metabolic Syndrome, Nishan Sudheera Kalupahana

Doctoral Dissertations

Obesity is a major health problem in the United States and worldwide. It increases the risk for type-2 diabetes and cardiovascular diseases. A chronic low-grade inflammation occurring in white adipose tissue (WAT) is causally linked to the development of insulin resistance (IR), metabolic syndrome and obesity-associated chronic diseases. The aim of this dissertation research was to elucidate the WAT function in metabolic syndrome using genetic (overexpression of an adipose pro-inflammatory hormone, angiotensinogen) and nutritional manipulations/approaches (caloric restriction and omega-3 fatty acids), with specific emphasis on the role of inflammation.

Previous research indicates that WAT renin-angiotensin system (RAS) is overactivated in …

The ‘Helper’ Phenotype: A Symbiotic Interaction Between Prochlorococcus And Hydrogen Peroxide Scavenging Microorganisms, James Jeffrey Morris

Doctoral Dissertations

The unicellular cyanobacterium Prochlorococcus is the numerically dominant photosynthetic organism throughout the temperate and tropical open oceans, but it is difficult to grow in pure cultures. We developed a system for rendering spontaneous streptomycin-resistant mutants of Prochlorococcus axenic by diluting them to extinction in the presence of “helper” heterotrophic bacteria, allowing them to grow to high cell concentrations, and then killing the helpers with streptomycin. Using axenic strains obtained in this fashion, we demonstrated that Prochlorococcus experiences a number of growth defects in dilute axenic culture, including reduced growth rate, inability to form colonies on solid media, and higher incidence …

A Comparison Of Commonly Used Accelerometer Based Activity Monitors In Controlled And Free-Living Environment, Yuri Feito

Doctoral Dissertations

This dissertation was designed to determine the effects of body mass index (BMI) and walking speed on activity monitor outputs. A secondary purpose was to compare the activity monitors’ performance in a free-living environment. In the first experiment, 71 participants wore three waist-mounted activity monitors (Actical, ActiGraph, and NL-2000) and an ankle-mounted device (StepWatch 3) while walking on a treadmill (40, 67 and 94 m/min). The tilt angle of each device was measured. The Actical recorded 26% higher activity counts (P < 0.01) in obese persons with a tilt <10 degrees, compared to normal weight persons. The ActiGraph was unaffected by BMI or tilt angle. In the second experiment, the steps recorded by the devices were compared to actual steps. Speed had the greatest influence on the accuracy these devices. At 40 m/min, the ActiGraph was the least accurate device for normal weight (38%), overweight (46%) and obese (48%) individuals. The Actical, NL-2000 and StepWatch averaged 65%, 73% and 99% of steps taken, respectively. Lastly, several generations of the ActiGraph (7164, GT1M, and GT3X), and other research grade activity monitors (Actical; ActivPAL; and Digi-Walker) were compared to a criterion measure of steps. Fifty-six participants performed treadmill walking (40, 54, 67, 80 and 94 m/min) and wore the devices for 24-hours under free-living conditions. BMI did not affect step count accuracy during treadmill walking. The StepWatch, PAL, and the AG7164 were the most accurate across all speeds; the other devices were only accurate at the faster speeds. In the free-living environment, all devices recorded about 75% of StepWatch-determined steps, except the AG7164 (99%). Based on these findings, we conclude that BMI does not affect the output of these activity monitors. However, waist-borne activity monitors are highly susceptible to under-counting steps at walking speeds below 67 m/min, or stepping rates below 100 steps/min. An activity monitor worn on the ankle is less susceptible to these speed effects and provides the greatest accuracy for step counting.

The Relationship Between Parental Literacy And Language Practices And Beliefs And Toddlers’ Emergent Literacy Skills, Claire Maples Edwards

Doctoral Dissertations

This study involved the examination of parental beliefs and practices about early literacy and language and how they influence observed literacy behaviors of their 18-36 month old toddlers. Observed literacy behaviors of the toddlers included phonological awareness (PA) and written language awareness (WLA). The objectives of this study were to (a) characterize the emergent literacy behaviors of toddlers, (b) characterize parental beliefs and practices regarding emergent literacy with respect to toddlers, and (c) determine the relationship between toddlers’ emergent literacy behaviors and their parents’ beliefs and behaviors. Participants included 15 mother-toddler dyads. Mean age of mothers was 35.2 years (SD …