Biology Commons^™

Evolution And Natural Selection Of Olfactory Receptor Genes In Hawaiian Drosophila, Ngoc H. Ly

UNLV Theses, Dissertations, Professional Papers, and Capstones

The olfactory system is a powerful tool for sensing countless odorants. In Drosophila, the olfactory system is critical for detecting food, finding mates, laying eggs, avoiding predators, and adapting to new environments. Understanding the olfactory system in Drosophila will advance our knowledge of sensory biology in various insects and vertebrates, including humans. Drosophila has been a valuable model for biology since the early 1900s, and the Drosophila melanogaster olfactory system is well-studied. The Hawaiian Drosophila represent approximately 1/3 of the world’s Drosophila, however, there is limited research on Hawaiian Drosophila olfactory genes. We conducted a comparative analysis of …

Cellular Heat Responses Of Desert Mammals Promote Survival In Extreme Conditions, Janessa Montenegro

UNLV Theses, Dissertations, Professional Papers, and Capstones

Increasing temperatures with the potential for heat stress is among the future threats facing many mammals. Cellular mechanisms to maintain homeostasis in the face of heat stress likely differ across species based on naturally tolerated intracellular variability. In some mammals, the homeostatic set point in cells has a narrow range. Other species tolerate more varied intracellular conditions, including in temperature. Heat stress responses of cultured dermal fibroblasts from several mammals were compared to detect cell proliferation and cellular death (chapter 2). Cells from heat- tolerant species (13-lined ground squirrel, dromedary camel, round-tailed ground squirrel, and white-tailed antelope squirrel) were compared …

Cell-Specific Mechanisms Of Microrna Modulation Of Anoctamin-1 (Ano1) In Oral Cancer, Daniel Hou

UNLV Theses, Dissertations, Professional Papers, and Capstones

Anoctamin-1 (ANO1) is a calcium-gated chloride ion channel with multiple physiological roles, including transepithelial ion transport, smooth muscle contraction, salivary secretion, and nociception. Recently, ANO1 has been identified to play a key role in cancer progression. ANO1 is overexpressed in different types of cancer, including oral cancer. ANO1 overexpression is commonly the result of ANO1 gene amplification on the chromosome 11q13 locus. In cancer cells, ANO1 upregulation has been reported to promote cell proliferation and migration of tumor cells, whereas ANO1 downregulation induces apoptosis through multiple signaling pathways. As such, ANO1 is now considered a useful biomarker for cancer progression …

Poop! There It Is! Anti-Germinants And Biological Variables As Modulators Of Clostridioides Difficile Infection (Cdi), Jacqueline Renee Phan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Clostridioides difficile infection (CDI) is a major cause of antibiotic-associated diarrhea. Due to its insidious nature, the Centers for Disease Control and Prevention (CDC) has declared CDI an urgent threat. A key characteristic of C. difficile is its ability to form dormant spores that act as the infectious vehicles for disease. In the gut, spores recognize bile salts to germinate into toxin-producing cells.Dysbiosis of the gut microbiome is a key factor in allowing the C. difficile spores to germinate. Normal gut microbiota naturally protects from CDI. However, biological variables such as diet and sex have been found to modulate to …

Desert Spring Prokaryotes And Benthic Macroinvertebrates: Geological And Ecological Controls, Ariel D. Friel

UNLV Theses, Dissertations, Professional Papers, and Capstones

Desert springs are aquatic oases, being considered among the most diverse and imperiled ecosystems on Earth. Despite the ecological significance and threatened status of desert springs, few studies have surveyed the microorganisms in these systems or their interactions with other community members. The primary goal of this dissertation was to describe the major controls influencing the community ecology of prokaryotic and BMI communities in cold- and moderate-temperature desert springs of the southern hydrographic Great Basin. Chapter 1 provides a broad overview of spring ecosystems and of each chapter included in this dissertation. Chapter 2 documents the first-ever, regional-scale survey of …

The Effects Of Habitat Isolation On Fine-Scale Genetic And Geographic Structure Of Populations Of Two Threatened Endemic Insects In Southern Nevada, Pseudocotalpa Giulianii And Icaricia Shasta Charlestonensis, Kristen Tovar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Assessing the role geographic isolation and ecological specialization have on phylogeographic patterns contributes to our understanding of the evolutionary history of a species and the processes that erode genetic diversity. I used mitochondrial and nuclear genomic sequences to assess whether habitat isolation has shaped the fine-scale patterns of present-day genetic structure and diversity in two threatened insect species endemic to southern Nevada. Pseudocotalpa giulianii (Coleoptera; Scarabaeidae) is a dune obligate scarab beetle endemic to only two small, isolated sand dunes in Nye County, Nevada, with a usable habitat of less than 4.2 km sq that is impacted by on-going degradation. …

Biochemical Characterization Of Fsa1572 From Fervidibacter Sacchari, The First Hyperthermophilic Gh50 With Β-1, 4-Glucanase Activity, Jonathan Covington

UNLV Theses, Dissertations, Professional Papers, and Capstones

The bacterium Fervidibacter sacchari is an aerobic hyperthermophile that catabolizes various polysaccharides and is the only cultivated member of the class Fervidibacteria within the phylum Armatimonadota. Among its glycoside hydrolase (GH) cache is an enzyme from GH family 50 (GH50), an understudied family with only 25 characterized representatives and two known activities from 1,518 predicted members in the Carbohydrate-Active EnZyme (CAZy) Database. Here, we expressed, purified, and functionally characterized an extracellular GH50 from F. sacchari called Fsa1572. Using colorimetric assays, we show it has novel β-1,4-glucanase activity and only weak agarose activity that is typical for GH50 enzymes. The purified …

Optimizing Resin Infiltration Treatment Of Post-Orthodontic White Spot Lesions By Increasing Infiltrant Penetration Duration — In Vitro Study, Hahnnah Park

UNLV Theses, Dissertations, Professional Papers, and Capstones

Background: This study focuses on evaluating the effect of increasing duration allowed for resin infiltrant penetration in improving the aesthetic outcome of resin infiltration treatment. Additional investigations into repeat treatment and long-term stability were also conducted. Artifically created white spot lesions were induced on one hundred extracted teeth made up of either incisors or canines. Teeth were divided into enamel and dentin groups depending on the extent of the lesion and then further subdivided into varying treatment protocol groups: 3-minute, 6-minute, and 9-minute penetration time. Teeth were thermocycled for one clinical year and then divided into a repeat treatment and …

Characterization Of The Thermophilic Xlanase Fsa272 From Candidatus Fervidibacter Sacchari Belonging To Glycoside Hydrolase Family Gh10, Nicole Torosian, Jonathan K. Covington, Allison M. Cook, Nancy O. Nou, Jan-Fang Cheng

Undergraduate Research Symposium Posters

Candidatus Fervidibacter sacchari is a novel, facultatively anaerobic, hyperthermophilic bacterium found in terrestrial geothermal springs globally. Its genome encodes 115 putative glycoside hydrolase enzymes that are predicted to hydrolyze glycosidic bonds between carbohydrates. Fsa272, a member of the glycoside hydrolase family 10, was synthesized and cloned into Escherichia coli strain T7 Express. The transformed E. coli was grown with LB broth and ampicillin at 37°C. Fsa272 expression was induced with isopropylthio-beta-galactoside (IPTG), and the lysate was heat purified for 15 minutes at 80° C. The 3,5-dinitrosalicylic acid assay identified xylanase activity with a pH range of 4.5 to 10.5 (pHopt …

Quantifying The Effect Of Disturbance On Native Mojave Desert Shrubs, Tamara J. Wynne

UNLV Theses, Dissertations, Professional Papers, and Capstones

Disturbance can come in many different forms. In our studies, we looked at the impact of a solar photovoltaic facility on native plants growing inside and outside of the facility, alteration in precipitation (simulated) on four native shrubs and the impact of applying supplemental water as a function of volume and frequency to establish native shrubs such as might occur at restoration sites. Disturbance is becoming a more common phenomenon in many ecosystems throughout the world, increasing the need for studies that quantify the impact at the plant and ecosystem level. Each research project revealed different plant responses, such as …

Hunter-Gatherers In Context: Hadzabe People And Early Nutrition Transition, Trevor Pollom

UNLV Theses, Dissertations, Professional Papers, and Capstones

The current study utilizes a mixed-methods approach to investigate the processes that influence landcover change and nutrition transitions in the Lake Eyasi Basin area of Northern Tanzania. In doing so, it provides unique insights into the behavior and biology of Hadzabe foragers living in the Yaeda Valley during the early stages of nutrition transition and provides much needed context for scientific literature that has been derived from this region. The current study answers the following questions: 1) How can historical and ethnographic maps, combined with present-day landcover classifications, inform our understanding of the people(s), spaces, and places of Lake Eyasi? …

The Utilization Of Crispr/Cas9 In Monogenic Disorders Authors, Shauna M. Mellor

Spectra Undergraduate Research Journal

This paper is a literature review of various scientific research papers, exploring the recent scientific advancement in the field of genetic engineering. The research presented is a foundational tool, building awareness on the implications of CRISPR/ Cas9 technology. CRISPR/ Cas9 was first discovered through the study of bacterial immune systems, fighting against viral infections. Manipulation of the Cas9 protein would eventually lead to target specific, gene-altering medicines for human organisms. CRISPR/ Cas 9 technology has begun to show promise as an effective treatment for certain monogenic disorders. Despite this, time is required before its efficacy as a proven genetic treatment …

Toward Building Science Literacy, Kathryn Rafferty

UNLV Best Teaching Practices Expo

Reading scientific literature is a critical science competency that proves difficult to “teach.” Students enter our classes with varying science vocabularies, and many suffer imposter syndrome when reading technical reports because they do not yet identify as capable scientists. The “Science Literacy” assignment guides students to develop and expand strategies to read science articles. Over the semester, students read 5 to 6 articles ranging from peer-reviewed manuscripts to popular science magazines to science blogs about sequencing Ozzy Osbourne's DNA. In Canvas Discussion boards, they a guiding set of questions and then respond to their peers. This assignment is a low-stakes …

Linking Extreme High Air Temperature Events To Wildfire And Environmental Variation To Water Balance Partitioning In The Western Us, Neil Savage

UNLV Theses, Dissertations, Professional Papers, and Capstones

Chapter 1

Wildfire activity has increased across the western United States in recent decades, causing significant damage to ecosystem services and human communities. The Sierra Nevada region, in particular, has experienced substantial increases in the ignition frequency, severity, and extent of large wildfires. To partly disentangle the complex processes underlying wildfire risk, I developed a simple approach to link natural wildfire ignition patterns to changing seasonal temperatures and extreme high and low air temperature events across the Sierra Nevada region from 1992—2015. Extreme event analyses focused on the association between the magnitude and frequency of occurrence of extreme temperature events …

Differential Gene Expression In Starvation Selected Drosophila Melanogaster, Katherine Schultz

UNLV Theses, Dissertations, Professional Papers, and Capstones

Fruit flies that have been selected for starvation resistance can be used in experimental studies to study physiological processes. Both their genomes and their phenotypes, especially metabolism, change significantly as a result of artificial selection. Starvation selected flies develop slower and are larger due to higher lipid content as adults. We used RNAseq to study gene expression in third instar larval fat body tissue from selected and control lines at the same chronological time point, when the fed control (“FC”) lines were wandering, and the starvation selected (“SS”) lines were in the third larval instar but not yet wandering due …

Distributions And Habitat Associations Of Blue Point Pyrgulopsis And Blue Point Tryonia, Chenoa Janine Wilcox

UNLV Theses, Dissertations, Professional Papers, and Capstones

Springsnails and other crenophilic species are often of conservation concern due to endemism, narrow habitat requirements, and susceptibility to habitat degradation. Because there is a distinct lack of natural history information for many of these organisms, management of species that are of concern is often based on data from non-target species related to the species of interest. In this thesis, I provide background information regarding springsnails in western North America (Chapter 1), describe a study investigating the distribution and habitat associations of two springsnails endemic to a single spring (Chapter 2), and provide supplemental information on habitat characteristics associated with …

Neurofibromatosis 1: Discovery, Treatment And Social Impact, Betsua Garcia, Arsen Khachatryan

Undergraduate Research Symposium Posters

The purpose of this timeline research project is to provide an outline of the discovery of Neurofibromatosis 1 to identify gaps in knowledge. Frederick von Recklinghausen is credited with the disease’s classification in 1882 when he observed two different cases of patients with neurofibromas. Current research of the disease involves its characterization at a molecular and genetic level. The symptoms of the disease include non-cancerous tumors in the nervous system (neurofibromas) and optic nerves (optic nerve gliomas), as well as cafe-au-lait spots around the axillary and groin areas. It tends to occur in 1 out of 3,000 births globally without …

Tissue-Specific Responses From A Global Developmental Signal: A Detailed Subcellular Analysis Of The 20e And Rab Signaling Pathways Controlling Exocrine Secretion During Drosophila Development, Nichalas Nelson

UNLV Theses, Dissertations, Professional Papers, and Capstones

During metamorphosis, the steroid hormone 20-hydroxecydysone (20E) triggers a plethora of tissue-specific responses in the common fruit fly, Drosophila melanogaster. The salivary glands are exocrine organs that respond to a large pulse of 20E to secrete a massive cargo of stored glycoproteins called glue. Because the glands are amenable to ex vivo-organ culture and powerful genetic manipulations, they are an excellent model for studying the conserved developmental and physiological signaling pathways that regulate the general function of these specialized secretory tissues. Our lab has generated transgenic animals in which the secreted glue molecules are tagged with fluorescent proteins. I have …

Microbe-Mineral Interactions During Exceptional Fossil Preservation, Stromatolite Formation, And Desert Varnish Growth, Michael Strange

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Ediacaran to Cambrian Deep Spring Formation consists of mixed carbonate-siliciclastic strata which contain an increasingly complex and biogeographically important biota. Past investigations of the Deep Spring Formation at Mt. Dunfee, Nevada, explored the highly diverse microbialite reefs consisting of a wide range of stromatolite morphologies which exerted significant control on local sedimentation and topography. Early investigations also documented the biomineralizing metazoan Cloudina (an Ediacaran index fossil). However, recent exploration of the area has resulted in the discovery of several new metazoan fossil communities consisting of a diverse assemblage of Ediacaran soft-tissue tubicolous vermiforms (tube fossils) similar to Cloudina. The …

Artificial Nightlight Alters The Predator–Prey Dynamics Of An Apex Carnivore, Mark A. Ditmer, David C. Stoner, Clinton D. Francis, Jesse R. Barber, James D. Forster, David M. Choate, Kirsten E. Ironside, Kathleen M. Longshore, Kent R. Hersey, Randy T. Larsen, Brock R. Mcmillan, Daniel D. Olson, Alyson M. Andreasen, Jon P. Beckmann, P. Brandon Holton, Terry A. Messmer, Neil H. Carter

Life Sciences Faculty Research

Artificial nightlight is increasingly recognized as an important environmental disturbance that influences the habitats and fitness of numerous species. However, its effects on wide‐ranging vertebrates and their interactions remain unclear. Light pollution has the potential to amplify land‐use change, and as such, answering the question of how this sensory stimulant affects behavior and habitat use of species valued for their ecological roles and economic impacts is critical for conservation and land‐use planning. Here, we combined satellite‐derived estimates of light pollution, with GPS‐data from cougars Puma concolor (n = 56), mule deer Odocoileus hemionus (n = 263) and locations of cougar‐killed …

Transcriptional Control Of Virulence Genes In The Bacterial Pathogen Shigella Flexneri, Joy Asami Mckenna

UNLV Theses, Dissertations, Professional Papers, and Capstones

Shigella species, the causal agents of bacillary dysentery, use a type III secretion system (T3SS) to inject two waves of virulence proteins, known as effectors, into the human colonic epithelium to subvert host cell machinery. Transcriptional regulation of these virulence genes is controlled by the three-tiered VirF/VirB/MxiE signaling cascade. Of these, VirB has the largest regulon (~50 genes); however, VirB regulatory properties are poorly understood. To date, VirB is known to function to counter or 'anti-silence' transcriptional silencing mediated by the histone-like nucleoid structuring protein H-NS. To better understand VirB regulation, my colleagues and I chose to better define the …

Can Desert Mosses Hide From Climate Change? The Ecophysiological Importance Of Habitat Buffering & Water Relations To A Keystone Biocrust Moss In The Mojave Desert, Theresa Ann Clark

UNLV Theses, Dissertations, Professional Papers, and Capstones

Empirical and observational studies suggest a keystone biocrust moss, Syntrichia caninervis, may be sensitive to future climate change in the American Southwest due to its uniquely sensitive water relations that appear particularly challenged during summer hydration-desiccation cycles. However, the potential mitigating roles of habitat buffering, acclimatization, and winter recovery on the vulnerability of this species remain largely unexplored. I investigated potential abiotic and biotic resiliency factors driving summer stress resistance and recovery in S. caninervis along present-day aridity gradients in the Mojave Desert to strengthen the climate change vulnerability assessment for this species common to biocrusts of North America, northern …

The Influence Of G4 Dna Structures On Stationary Phase Mutagenesis In Bacillus Subtilis, Tatiana Ermi

UNLV Theses, Dissertations, Professional Papers, and Capstones

Until the late 1980’s it was widely understood that bacterial variance emerges randomly during growth. Research that followed has convincingly shown evidence for mutations arising in non-growing conditions, a phenomenon known as stationary-phase mutagenesis. In Bacillus subtilis, an elegant mutagenic mechanism has been elucidated in non-growing cells that biases mutations to transcribed regions of a subpopulation. One interesting possibility is that mutations can be further biased to hotspots within genes through alternate DNA structures known as non-B DNA. Non-B DNA have been linked to genomic instability and disease in humans, lesser is known about its role in bacteria. Here we …

Rapid Evolution Of Starvation Resistance In Drosophila: Physiological And Molecular Mechanisms, Austin Joseph Mckenna

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Gibbs lab has maintained starvation-selected Drosophila melanogaster for >130 generations. These starvation-selected flies evolved an obese phenotype with a suite of physiological differences compared to control-fed flies. Previous studies have shown that long-term starvation-selected Drosophila contain more lipids, have lower metabolic rates and develop more slowly than controls. This dissertation encompasses 1) Examining the molecular mechanisms contributing to starvation resistance, 2) Functional validation of the candidate plin1 allele, and 3) Rapid physiological and genomic evolution in starvation-selected Drosophila.

Starvation-selected Drosophila survive starvation conditions much longer than control-fed flies. This study took a simple approach to identify possible differences in …

Factors That Influence Persistence Of Biology Majors At A Hispanic-Serving Institution, Shetay Ashford-Hanserd, Kristy Daniel, Dana M. García, Jenn L. Idema

Journal of Research in Technical Careers

To promote diversity within the science, technology, engineering, and mathematics (STEM) workforce, we must identify factors that influence or hinder historically underrepresented minority (URM) students’ persistence to degrees in STEM. We documented potential factors that influence students’ persistence in an undergraduate biology program and created a 14-item, Likert-scale instrument. We recruited 137 undergraduate biology majors at a Hispanic-serving institution in Texas to report which factors they found influential in their decision to remain enrolled in their degree programs. We used a modified social cognitive career theory model of career choice to guide interpretation of the reported influences and identify patterns …

Trade-Offs Between Survival And Reproduction In Starvation-Selected Drosophila Melanogaster, Tammara Beeghly

UNLV Theses, Dissertations, Professional Papers, and Capstones

Evolutionary outcomes are demonstrated by traits that affect an organism’s schedule of reproduction and survival. These life history traits are reflected in an organism’s physiology, development and behavior. Environmental changes, such as availability of nutritional resources, can profoundly affect evolutionary outcomes of individuals and populations. When shortages arise, there will be trade-offs in the allocation of resources, where one trait prevails at the expense of another.

In the laboratory, we can mimic conditions in nature and study the specific effects of the conditions that we re-create. In our case, over 100 generations of Drosophila melanogaster have been selected for starvation …

Landscape Scale: Inter- And Intraspecific Variation In Plant Interactions Along A Stress Gradient In The Sheep Range Of Nevada, Jordan Dowell

UNLV Theses, Dissertations, Professional Papers, and Capstones

Impending threats to shrubland ecosystems, posed by climate change, necessitate niche modeling efforts to project vegetation range shifts. However, efforts often remain unguided by individual-scale interspecific plant interactions. The stress gradient hypothesis posits that facilitation should increase in areas of high abiotic stress, only if the individuals are able to ameliorate the surrounding area via functional traits. The Sheep Range of Nevada was used to assess the role of functional traits as predictors of plant association. Larrea tridentata, Coleogyne ramosissima, and Artemisia nova were selected as shrubs with variable life history strategies and ranges in order to identify general patterns …

Mojave Desert Plant Community Long-Term Response To Disturbance, Dominic M. Gentilcore

UNLV Theses, Dissertations, Professional Papers, and Capstones

All vegetation communities have been shaped by disturbances. This dissertation consists of three separate chapters: Blackbrush (Coleogyne ramosissima) natural regeneration in the Great Basin-Mojave Desert Transition Zone on two fires, Long-term Response to Fire in Eastern Mojave Desert semi-arid shrubland communities, and an Annotated Checklist of Gold Butte National Monument in the Mojave-Colorado Plateau Transition Zone. The section on blackbrush natural regeneration was a long-term dataset from two fires in Basin and Range National Monument that burned in 2008 with monitoring events in 2009, 2010, 2011, 2018 and 2019. The monitoring documented some of the strongest post-fire regeneration for the …

Restructuring Of The Axon Initial Segment In Mouse Models Of Neurodevelopmental Disorders, Rachel Ali Rodriguez

UNLV Theses, Dissertations, Professional Papers, and Capstones

Neurodevelopmental disorders (NDDs) affect more than 36% of children in countries with low- and middle- incomes (Boivin, 2015; McCoy, 2016). Interestingly, these heterogeneous disorders share a high incidence of epileptic seizures, suggesting a shared pathology. Seizures result when neuronal firing activity becomes disturbed and neurons fire excessively or in unregulated patterns. A key site in the control of neuronal firing patterns is the axon initial segment (AIS), where the local density of proteins and the morphology of the AIS in part determine the firing of neurons. We hypothesized that a disruption in the morphology and/or composition of the AIS can …

The Effect Of Pleistocene Glacial - Interglacial Cycles On Patterns Of Genetic Diversity And Differentiation Of Populations Of Leptodactylus Albilabris (White-Lipped Frog) In The Puerto Rican Bank, Andre Nguyen

UNLV Theses, Dissertations, Professional Papers, and Capstones

The historical distributional shifts of various species have been attributed to the glacial-interglacial cycles of the Pleistocene Epoch (2.6 mya – 10,000 ya). Sea level changes caused by Pleistocene glacial-interglacial cycles impacted the total area of landmasses, particularly in island systems. Cooler, glacial periods increased emergent (subaerial) island area via lower sea levels. Adjacent islands may have become connected through emergent land bridges, resulting in a larger subaerial landmass. Warmer interglacial periods led to higher sea levels, which in turn reduced island area, and in some cases, submerged land bridges, fragmenting larger islands into separate, smaller units. The Puerto Rican …