Life Sciences Commons^™

The Directional Effect Of Target Position On Spatial Selective Auditory Attention, Heesung Park

Dissertations, 2020-current

Spatial selective auditory attention plays a crucial role in listening in a mixture of competing speech sounds. Previous neuroimaging studies have reported alpha band neural activity modulated by auditory attention, along with the alpha lateralization corresponding to attentional focus. A greater cortical representation of the attended speech envelope compared to the ignored speech envelope was also found, a phenomenon known as 'neural speech tracking’. However, little is known about the neural activities when attentional focus is directed on speech sounds from behind the listener, even though understanding speech from behind is a common and essential aspect of daily life. The …

Pasturelands As Natural Climate Solutions: A Socioecological Study Of Tree Carbon And Beef Production Trade-Offs, Bela Starinchak

Masters Theses, 2020-current

Forest restoration is the most effective natural climate solution, with the potential to sequester 37% of the carbon dioxide (CO₂) needed to reach the Paris climate mitigation goal. Cattle pastures offer an underutilized opportunity to increase global forest restoration efforts, improve biodiversity, and maximize carbon storage through the adoption of management strategies that prioritize the incorporation of trees into pasturelands. However, remote estimations of tree carbon storage in pastoral systems have never been field-verified and their accuracy is unclear. Furthermore, the effect of increased trees on cattle production is understudied across biomes. Lastly, the restoration potential of these …

Locomotion And Life History In A Leaping Primate: Mechanics And Energetics Of Movement Throughout The Propithecus Lifespan, Nicholas Heslep

Masters Theses, 2020-current

Arboreal primates are typically altricial, exhibit long juvenile periods, and use dynamic locomotor behaviors that can be challenging and risky. Sifaka (Propithecus verreauxi) have particularly slow life histories for their size, with long juvenile periods, protracted reproductive careers, and long life spans. Slow somatic growth poses potential mechanical challenges for juvenile sifaka who use thigh-powered vertical clinging and leaping to follow group members during travel. I examined mechanical and energetic costs of movement in developing sifaka. I instrumented 8 wild sifaka (3 yearlings, 3 subadults, 2 adults) in 4 social groups with inertial sensors measuring tri-axial acceleration for …

Understanding Context Dependent Responses To Climate Change In Arizona Tiger Salamanders (Ambystoma Mavortium Nebulosum), Kentrell Richardson

Masters Theses, 2020-current

Future emissions scenarios project climate change to increase average global temperatures by at least two ℃ in the next 50 years resulting in changes in local climate and causing increased variability within microclimates. Ectotherms are especially sensitive to climate change due to their dependence on environmental temperatures to regulate physiological functions. Changes in temperature are likely to impact thermally cued processes within amphibians and result in changes in variable magnitudes and directions within local populations.

Salamanders were placed in cups and partially submerged in a water bath and heated at a rate of ~0.27℃/ minute. Once salamanders were unable to …

The Response Of Microcystis And The Microbiome To Exogenous Hydrogen Peroxide, Bryan A. Puma

Masters Theses, 2020-current

Microcystis spp. produce prolific annual blooms in freshwater systems worldwide. The success of these blooms depends heavily on the Microcystis spp. overcoming environmental factors such as oxidative stress caused by reactive oxygen species (ROS) like hydrogen peroxide. Most Microcystis genomes do not contain many genes for responding to oxidative stress, including those that encode the enzyme catalase. Other cyanobacteria such as Prochlorococcus that also lack hydrogen peroxide degrading enzymes have been shown to benefit from partnerships with heterotrophic bacteria. Microcystis spp. may also receive similar benefits from heterotrophic bacteria in the phycosphere. To test this hypothesis, we examined the …

Sequencing An Inserted Concatemer In Caenorhabditis Elegans Strain Hlh-29::Gfp, Simon T. Anderson

Senior Honors Projects, 2020-current

Hairy/Enhancer of Split (HES) proteins and their homologs play vital roles in the development of animals, and in the regulation of cancer and other diseases. HLH-29 is an REF-1 family protein and a Caenorhabditis elegans homolog of human HES proteins. A transgenic animal model has been developed to facilitate analyses of this protein, containing an inserted concatemer of the green fluorescent protein reporter gene, regulated by the hlh-29 promoter, and a mutant rol-6 allele. Though the strain has been used previously, the location and structure of the insertion has been unknown. Sequencing of the whole hlh-29::gfp genome with high-molecular weight …

Narrative Review: Food Image Use For Machine Learnings’ Function In Dietary Assessment And Real Time Nutrition Feedback And Education, Jason Fee

Masters Theses, 2020-current

Technology has played a key role in advancing the health and agriculture sectors to improve obesity rates, diseasecontrol, food waste, and overall health disparities. However, these health and lifestyle determinants continue to plague theUnited States population. While new technologies have been and are currently being developed to address these concerns, they may not be practical for the general population. Utilizing machine learning advancement in food recognition using smartphone technology may be a means to improve the dietary component of nutrition assessments while providing valuable nutrition feedback. This narrative review was conducted to assess the current state of the literature on …

Pre-Pulse Inhibition In Mutated Mice: Studying Compromised Microglial Cells To Discover New Genetic Connections To Autism, Bailey R. Kramarik

Senior Honors Projects, 2020-current

Microglial cells “play a pivotal role in refining neural networks during early critical periods” (Gabriele & Gray, 2020, p. 1). A disturbance in the functioning of these microglial cells contribute to specific characteristics of some neurodevelopmental disorders- including autism spectrum disorder. In this study, we used a mouse model to study disruptions in cell activity, as understanding the biological and genetic background of autism spectrum disorder could help us provide better treatment and therapy options to those diagnosed.

The mutated mice in this experiment have microglial cells with “compromised fractalkine signaling” (Gabriele & Gray, 2020, p. 4-5). We studied multimodal …

The Effect Of Acute Caffeine Withdrawal On Exercise Performance In Habitual Caffeine Users, Timothy D. Griest

Masters Theses, 2020-current

Purpose: The purpose of this study was to investigate how exercise performance is impacted by acute withdrawal from caffeine (CAF) in habitual users and if CAF ingestion will reverse the negative impact of withdrawal or have a net positive benefit. Methods: Ten recreational cyclists (age 39.1 ± 14.9 y; VO_2max 54.2 ± 6.2 mL/kg/min) who were habitual CAF consumers (394 ± 146 mg/d) completed four trials, each consisting of peak isokinetic torque testing and a 10-km time trial (TT). On each trial day, subjects consumed either 1.5 mg/kg CAF to prevent withdrawal or placebo (PLA) 8 hours before their …

The Effect Of Creatine Supplementation On Body Composition And Total Body Water Measured By Multi-Frequency Bioelectrical Impedance, Emily A. Buck

Masters Theses, 2020-current

Background: Acute fluid ingestion causes an increase in estimated body fat percentage (BF%) measurements by single frequency (SF-BIA) and multi-frequency bioelectrical impedance (MF-BIA). However, it is unknown if MF-BIA accurately measures total body water (TBW) and BF% after chronic fluid retention. Creatine supplementation causes fluid retention, and resultant increases in TBW and body mass. Research is needed to determine if MF-BIA is capable of detecting fluid retention secondary to creatine supplementation. Methods: 13 male and 14 female subjects (18-22 y) completed one week of creatine monohydrate or maltodextrin supplementation at a dose of 0.3 g/kg body weight. Subjects completed pre-supplementation …

The Effect Of Dietary Nitrate Supplementation On Physical And Cognitive Performance During Load Carriage In Military Cadets, Nicholas C. Bordonie

Masters Theses, 2020-current

Purpose: The purpose of this study was to determine the effects of dietary nitrate supplementation on physical and cognitive performance during exercise conducted under heavy pack load in military cadets. Methods: Ten college-aged males (VO_2max 56.2 ± 3.7 ml/kg/min) consumed 140mL/d of concentrated beetroot juice (BRJ; containing 12.8 mmol of dietary nitrate) or a placebo (PL; flavor, color, energy, and texture-matched with no dietary nitrate) for six days preceding an exercise trial. The trial consisted of 45 min of constant-load exercise on a treadmill at 4.83 km/h and 1.5% grade, followed immediately by a 1.6-km time-trial completed at maximal …

The Impact Of Iaa And Tryptophan On Microcystis Bloom Community Dynamics, Hunter R. Baylous

Masters Theses, 2020-current

Microcystis aeruginosa is a freshwater cyanobacterial species that degrades freshwater and brackish ecosystems due to its capacity to form toxic cyanobacterial harmful algal blooms (cyanoHABs). There both abiotic and the biotic factors that exacerbate the presence of cyanoHABs. Current research is looking at the microbial interactions that occur between microbes and phytoplankton. Microbes interact with cyanobacteria in the phycosphere, where nutrients are exchanged between the two. Understanding the chemical currencies exchanged can help to show interactions that are beneficial for cyanoHAB formation A key player in the growth promotion of cyanoHABs is hypothesized to be auxins, which are synthesized by …

Pilfering Passerines? Inter-Class Competition: A New Direction In Foraging Ecology, Shannon Gillen

Masters Theses, 2020-current

Life in the epigeal layer below leaf litterfall often goes unexplored. Shrews (Soricidae, 1910) have foraged in this microhabitat for millions of years, carving out an existence in harsh habitats around the world, ranging from the tropics to subarctic boreal tundra. Two shrew species that inhabit the Shenandoah Valley of Virginia, the least shrew (Cryptotis parva) and northern short-tailed shrew (Blarina brevicauda), were the focus of this study. Shrews make epigeal foraging trails while they continually forage for food, and caching is a way to save this food for times of low and sporadic food availability. …

The Effect Of Intensity And Duration Of Verification Stages On The Efficacy Of Vo2max Testing, Andrew Foster

Masters Theses, 2020-current

Purpose: To determine if changing the length of the recovery stage influences the effectiveness, or ability to confirm maximal oxygen consumption (VO_2max), of the verification phase and if the initial intensity of the stage has an impact on its effectiveness. Methods: 27 subjects (20 males and 7 females) performed four separate VO_2max tests separated by at least 48 hours. For each initial graded exercise test, starting speed was 3.0 mph and increased by 0.5 mph every minute until 6.0 mph was reached. After this point, elevation was increased by 3.0% every minute until volitional exhaustion. VO_{2 …}

Does A Bout Of Acute Resistance Exercise Attenuate The Post-Prandial Lipemic Response To A High Fat Meal In 50-80 Year-Old Adults, Summer Simulcik

Masters Theses, 2020-current

Background: A single high-fat meal (HFM) is known to elevate blood lipid levels above what is normal, resulting in postprandial lipemia (PPL). Chronic hyperlipemia has been associated with increased risk for cardiovascular disease (CVD) and type-2 diabetes mellitus (T2DM) development. Current physical activity (PA) guidelines recommend at least one set of 8-12 repetitions of each exercise to attenuate this risk. Adults older than 50 (OF) years (y) are at an increased risk for cardiometabolic disease compared to younger adults (YA). Aerobic exercise (AE) performed in the pre-prandial period has been observed to attenuate PPL in both OF and YA. However, …

Urban Habitats Impact The Song And Reproductive Success Of A Migratory Bird, The Gray Catbird (Dumetella Carolinensis), Sasha Ewing

Masters Theses, 2020-current

Urban environments are relatively recent on an evolutionary timescale, and, as such, they create novel selection pressures that may influence fitness and mate choice. Many ecologically significant factors change with increasing levels of urbanization, such as increasing anthropogenic noise, increasing impervious surface, and decreasing forest cover. There is growing empirical evidence that anthropogenic noise affects features of birdsong and, separately, that avian nesting success varies across an urban gradient, but rarely do studies examine both – a necessary step to elucidate the evolutionary potential of these novel pressures. I investigated song features, body morphometrics, and reproductive success in male gray …

Assessing Red Spruce (Picea Rubens) Restoration Potential Under Current And Future Predicted Climate Change In Virginia, Christian Brown

Masters Theses, 2020-current

Global climate change threatens many species across the planet. High-elevation species, such as red spruce (Picea rubens), face significant and immediate threats from climate change. Red spruce has faced anthropogenic disturbances for over a century and is only recently beginning to regenerate across its range, making it an ideal restoration candidate. Ecological niche modeling has become a common method of identifying the suitable habitat of a species, providing vital information to land managers carrying out restoration efforts. In this study ecological niche models were used in a novel way, predicting distribution and habitat suitability separately to determine the …

Urbanization Drives Changes In Avian Communities, Which Are Reflected In The Song Of A Vocal Mimic, Jaclyn Tolchin

Masters Theses, 2020-current

Urban landscapes present problems for wildlife including highly modified habitat, anthropogenic noise pollution, and competition for suitable habitat. These novel selection pressures can filter species present in urban habitats or result in changes to behavior. Recent studies show that some bird species sing differently (louder, higher pitch, faster) in noisier, urban areas compared to quieter, more rural areas, and that anthropogenic noise alone can exclude species. I investigated how the level of urbanization affects 1) bird species composition, and 2) the assemblage of species that a songbird mimics from the local bird community. I studied gray catbirds, Dumetella carolinensis, across …

Identifying Key Stream Restoration Variables In An Agriculturally Impaired Chesapeake Bay Watershed, Julia Portmann

Masters Theses, 2020-current

The Chesapeake Bay watershed spans several states, supports diverse ecosystems, and is crucial to local economies. However, agricultural practices in this region impair water quality. The Smith Creek watershed, within the Shenandoah Valley, was designated a showcase watershed in 2010 by the United States Department of Agriculture to demonstrate the efficacy of implementing restoration projects. We sampled fifteen farms ranging from unrestored to thirty-six years since restoration. At each site, we conducted a kick-net survey for macroinvertebrates, measured canopy cover, algal density, substrate size, and bank height and angle. We identified macroinvertebrates to family and calculated the Chesapeake Basin-wide Index …

Trauma Healing With The Neurosequential Model Of Therapy And Bal-A-Vis-X, Becky Johnston

Educational Specialist, 2020-current

Stigma related to childhood trauma is shifting with the help of advancements in the understanding of neurobiology and interventions that are proving to be effective for healing. There are immense costs and consequences for survivors of childhood trauma and their loved ones that were not so long ago considered irrelevant and the notion that kids bounce back from adversity was previously popular in the psychological community (Perry & Szalavitz, 2017). The broad strokes of Dr. Bruce Perry’s clinical intervention model, The Neurosequential Model of Therapy (NMT) describes a trauma-sensitive, sequential approach to changing the stress response within mental health counseling. …

Identifying The Molecular Pathways That Drive Retinal Degeneration In The Childhood Neurodegenerative Disease: Mucolipidosis Type Iv, Michael Pamonag

Masters Theses, 2020-current

Humans, like many other vertebrates, possess five Aristotelian senses (vision, olfaction, hearing, taste, and touch) which we use to experience and navigate our environment. Our visual system is the only source of light detection and light signaling in our bodies. This makes our visual system essential for detecting movement, distance, time of day, and seasonal changes in the length of days within our environment. The visual systems of most animals are designed to capture photons of visible light and convert that energy into a neurological signal (visual signal) to be transmitted to brain regions responsible for visual perception1 . This …

Is Immediate Flexibility Present In A Vocal Mimic, The Gray Catbird (Dumetella Carolinensis), Across An Urban Gradient?, Shannon K. Eppert

Masters Theses, 2020-current

Increasing urbanization has increased anthropogenic noise levels near developed areas. Urban noise is high amplitude and low-frequency, and these frequencies can overlap with the signals animals use to communicate, including bird songs. Many urban birds sing higher minimum frequencies in urban areas, which avoids some masking by noise, but the mechanism behind this difference is not well understood. Immediate flexibility is the ability to alter song in real-time in the presence of sudden noise, allowing for avoidance of masking and better signal transmission. I investigated if male catbirds increased signal transmission in the presence of anthropogenic versus high-frequency noise playback …

A Stable-Isotope Probing Approach To Modeling Bidirectional Nutrient Exchange In The Microcystis Phycosphere, Malia Gardner

Masters Theses, 2020-current

Cyanobacterial harmful algal blooms (cHABs) plague freshwater systems worldwide and are projected to increase in intensity in the coming decades. cHABs damage aquatic ecosystems by blocking light penetration into the water column, creating hypoxic conditions, and releasing toxins. One of the most prolific cHAB formers is the cosmopolitan genus of cyanobacteria Microcystis. Global climate change and anthropogenic loading of nutrients such as nitrogen (N) and phosphorus (P) fuel Microcystis bloom formation. Increasing global temperatures favor Microcystis because of its high optimal growth temperature. N input is of particular importance for Microcystis because it is unable to fix atmospheric N, …

Ecophysiology Of Toxic Bloom-Forming Cyanobacteria And Their Symbionts, Dominique J. Lockwood

Masters Theses, 2020-current

Currently, there is a pernicious microbe in the genus Microcystis that is putting the world’s freshwater resources at risk. A member of the phylum Cyanobacteria, otherwise referred to as blue-green algae, Microcystis forms massive algal blooms in lakes and has the potential to produce a toxin, which does not only harm humans, but also pets, livestock, and aquatic life. As recently as 2016, in the city of Toledo, Ohio, nearly 1 million residents went without clean drinking water for an entire weekend due to one of these Microcystis blooms. However, Microcystis does not only bloom in Ohio. In fact, …

Population Study Of Native And Invasive Turtles In Harrisonburg, Virginia, David R. Weisenbeck

Senior Honors Projects, 2020-current

The Red-eared Slider, Trachemys scripta is an invasive species responsible for declines in turtle species across the world. Trachemys scripta is native to two parts of southern Virginia but the species has been introduced throughout the rest of the state, often related to the release of pet trade animals. This study aimed to identify the extent of Trachemys scripta’s establishment and impact on native species in Harrisonburg, Virginia. Turtles were trapped in a mark-recapture study during the springs and summers of 2018, 2019, and 2020 in four local ponds in Harrisonburg, Virginia. Cormack-Jolly-Seber population models were constructed using data …

Postprandial Exhaled Nitric Oxide Responses In Older And Younger Adults With And Without Acute Exercise, Molly Miller

Masters Theses, 2020-current

A single high fat meal (HFM) increases airway inflammation in young, healthy individuals. Additionally, aging increases airway resistance and inflammation, though the airway inflammatory response to a HFM has not been investigated. Exercise is a natural anti-inflammatory, but has yet to be administered with a HFM as a method to study postprandial airway inflammation in older adults. Purpose: To investigate whether older individuals have greater postprandial airway inflammation compared to younger counterparts, and to explore whether exercise may modify the postprandial airway response in older adults. Methods: 12 younger adults (23.3±3.9 years; 5 M/7 F) and 12 older adults (67.7±6 …

Comparing The Effect Of Four Propagation Techniques On Hybrid Chestnut Seedling Quality, Taylor Evans

Masters Theses, 2020-current

Extensive resources have been used to breed hybrid chestnuts for reintroduction into the historical range of the American chestnut (Castanea dentata). Improving seedling quality is an efficacious method to improving restoration outcomes and nursery propagation methods can be selected to improve seedling quality, increasing the likelihood of survival. Four production methods (bed grown, air prune beds, container grown, and the Root Production Method®) and three media types (field soil, peat-perlite-vermiculite mix, and pine bark-rice hulls-sand mix) were compared across four measures of seedling quality (height, root collar diameter, root volume, and number of first order lateral roots) to …

Plant-Pollinator Network Dynamics Of The Little Fork Shale Barren, Sarah N. Brown

Masters Theses, 2020-current

Shale barrens are steep sloping mountainside ecosystems characterized by rocky Upper Devonian age shale substrate, high light, and low water availability. They form an array of biogeographical “islands” throughout Mid-Appalachia whose niche dynamics, response to disturbance, and pollination ecology remain to be investigated. Using network analysis, this project addresses three objectives to fill gaps in shale barren pollination ecology. (i) Compare vegetative species composition, richness, diversity, and evenness to a descriptive vegetation study completed at the same site 27 years prior. ii) Outline the topology of plant-pollinator networks including identifying phenologically accurate networks, the architecture of such networks, and identifying …

Influence Of Testosterone On Male-Male Competition In The Red-Sided Garter Snake, Thamnophis Sirtalis Parietalis, Isabella M. G. Bukovich

Senior Honors Projects, 2020-current

Female mimicry in the red-sided garter snake, Thamnophis sirtalis parietalis, is described in several well-studied evolutionary advantages, but an aspect that remains elusive is how reproductive traits are linked to the 3-fold higher circulating androgens in males with this phenotype. In this study, we implanted male garter snakes (n=15 per group) with either a blank implant (SHAM; control) or a T implant, the latter simulating the female mimic phenotype. Following simulated low-temperature dormancy, males were scored for courtship intensity over three days of behavioral trials with females housed in the same facility. Males were sacrificed, and sperm were collected …

The Effects Of Exercise On Breastmilk Composition And Supply: A Critical Literature Review, Jewell Mcroy

Masters Theses, 2020-current

It is well established that breastfeeding provides dual benefits to both the mother and the infant and is the preferred method of providing nutrients to infants essential for growth and development. Participating in regular physical exercise is also well-supported by research to be beneficial to one’s overall health and quality of life. Currently there are no physical activity guidelines developed for women who are postpartum and breastfeeding. An online database search was conducted; three articles met the inclusion criteria and were included within the review. Studies were included if there were direct measures of human breastmilk composition, supply/volume, and included …