Digital Commons Network^™

Investigating The Roles Of Plants, Fungi, And Biocrusts In Nutrient Movement Within Dryland Ecosystems, Catherine E. Cort

Open Access Theses & Dissertations

In dryland ecosystems, plant productivity and microbial decomposition are often separated in space and time due to the asynchronous availability of soil moisture and organic matter inputs. It has been proposed that fungi play a key functional role in connecting these cycles by facilitating movement of water, carbon (C), and nitrogen (N) through a network of shared hyphae between plant roots and biological soil crust (biocrust) communities at the soil surface. This connection, also known as the â??fungal loop,â?? effectively re-couples processes of nutrient release and uptake between primary producers and minimizes ecosystem N losses due to leaching, erosion, and …

Activity Patterns Of Whiptail Lizards (Aspidoscelis) Found In The Northern Chihuahuan Desert, Guillermo Alvarez

Open Access Theses & Dissertations

Traditional lizard pitfall traps were modified to allow organisms to escape, while collecting valuable ecological data. Modified camera traps were capable of detecting the same species as traditional traps in a semi-arid environment, without posing the associated mortality risks. Pitfall-camera traps were used to sample the activity of the Side-blotched Lizard (Uta stansburiana) and the Southwestern Fence Lizard (Sceloporus cowlesi) in an urban wetland during four continuous years. Evaluations on activity pattern and the activity overlap between the two species revealed extensive overlap, with minor but significant seasonal shifts mediating coexistence. Traps were also effective at detecting other reptiles, invertebrates, …

Evaluation Of Evapotranspiration Estimates Using An Existing Hybrid Machine Learning Model In A Natural And A Managed Dryland Site, Katya Esquivel Herrera

Open Access Theses & Dissertations

Evapotranspiration (ET) is a critical component of the hydrologic cycle, encompassing both evaporative water loss from surfaces and transpiration through plant stomata. The environmental factors influencing ET include water and energy availability, atmospheric capacity for water uptake, and various meteorological variables. ET serves as a unique climate variable linking water, energy, and carbon cycles. In agroecosystems, accurate ET quantification is vital for optimizing water use efficiency, irrigation management, and crop yield. Traditional methods for ET estimation involve direct measurements and indirect models, with both presenting limitations.

Recent years have witnessed the integration of remote sensing and machine learning (ML) algorithms …

The Physiological Effects Of Acute And Ramp Hypoxic Exposure During Simulated Flight Tasks, Jasmin Renee Jenkins

Open Access Theses & Dissertations

The purpose of the present study was to examine the effects of hypoxia at simulated altitudes of FiO2 15.4% (8000’ equivalent), FiO2 13.2% (12,000’ equivalent), and a Ramp Hypoxic exposure on perceived workload, cardiovascular activity, electrodermal activity, oximetry, and flight simulator performance. A total of 17 participants (10 female & 7 males; mean ± SEM, age 24.82±1.6 yrs, BMI 25.87±1.0 who were apparently healthy, asymptomatic, and physically active performed 3 flight tasks using a video game head-mounted display (HMD) flight simulator while exposed to simulated altitudes of Normoxia, FiO2 15.4%, FiO2 13.2% and a Ramp Hypoxic Exposure (breathing at 8,000 …

Developing Next-Generation Ecoinformatics Tools For Advancing Global Change Science, Ifeanyi H. Nwigboji

Open Access Theses & Dissertations

Ecosystems are responding to a variety of human-induced, interlinked stressors that have emerged from changing climate, alteration to the global water cycle, sea-level rise, and land use and land cover change, among others. Quantifying these changes and their associated impacts on ecosystems requires a huge amount of long-term data. Due to advances in data collection techniques, such as remote sensing platforms, environmental sensors, synthesized datasets, and various software technologies, the volume and variety of long-term ecological data being collected has tremendously increased. Although there are several complex models and analyses that are increasingly parametrized with data from such sensors, there …

Lizard Communities In A Shifting Landscape: The Current State Of Insectivorous Lizard Communities In The Jornada Basin Between Grassland, Mesquite Dune, And Creosote Bush Habitats In A Semi-Arid Landscape Undergoing Shrubification, Julie Marie Schlichte

Open Access Theses & Dissertations

Lizard communities in arid lands can act as model systems of how diversity and abundance are impacted in the face of ongoing climate variability and change, as they are sensitive to shifts in precipitation, temperature, and changing vegetation structure. The main research question we hope to answer is how the community composition of lizards varies between dominant vegetation types (Mesquite dunes, grasslands, and Creosote Bush flats). Nine sites (3 of each dominant vegetation type) with 16 pitfall traps each (n = 144) were surveyed from June 2016 -- June 2017. 12 lizard species were captured, consisting of 923 total captures …

Evolution Of Forest Bitis (Macrocerastes) In Africa: Phylogeography, Population Genetics, And Potential As A Model For Batesian Mimicry, Eugene Richard Vaughan

Open Access Theses & Dissertations

The major biogeographical patterns characterizing the diversification of widely distributed species in the African rainforest remain poorly understood because of the low number of well-sampled studies that are focused on this region. I examine the phylogeography and population genetics of two broadly sympatric sister lineages of large African forest vipers (genus Bitis, subgenus Macrocerastes), the rhinoceros viper (B. nasicornis) and the Gaboon vipers (B. gabonica and B. rhinoceros). Despite their close relationship, these two lineages have notably different patterns of divergence in time and space. A time-calibrated phylogeny with sequence data from five genes, and population structure and PCA analyses …

The Role Of The Cholesterol Synthesis Pathway In Primitive Erythropoiesis, Jose Hernandez

Open Access Theses & Dissertations

Erythropoiesis is the process by which new red blood cells (RBCs) are formed and defects in this process can lead to anemia or thalassemia. The GATA1 transcription factor is an established mediator of RBC development. However, the upstream mechanisms that regulate the expression of GATA1 are not completely characterized. Cholesterol is 1 potential upstream mediator of GATA1 expression because previously published studies suggest that defects in cholesterol synthesis disrupt RBC differentiation. Here we characterize RBC development in a zebrafish harboring a single missense mutation in the hmgcs1 gene (Vu57 allele). Hmgcs1 encodes the first enzyme in the cholesterol synthesis pathway …

Metrics For Comparison Of Complex Networks, Clarissa Reyes

Open Access Theses & Dissertations

Heuristic network statistics are used as a preliminary approach to identify change across networks. In networks where there is known node correspondence (KNC), conventional network comparison methods include taking a norm of the difference matrix, or calculating dissimilarity measures like DeltaCon and cut distance. Since different KNC measures provide varying insight to the network comparison problem, we propose employing Rank Score Characteristic Functions (RSCFs) and the rank-score process as a method for reaching a consensus when ranking quantified change across multiple pairs of networks â?? which is particularly useful for ranking change across subpopulations or subgraphs. Additionally, we propose a …

Repositioning Propranolol To Block Mitogenic Signaling In Breast Cancer, Alexa Noel Montoya

Open Access Theses & Dissertations

Breast cancer is the second most diagnosed cancer among women and is about 30% of all new cases of female cancers each year. It is projected that 1 in 8 every U.S. woman (about 13%) develop invasive breast cancer over the course of her lifetime. While advances in cancer research have made it possible to elucidate several breast cancer genomic subtypes, and develop new novel therapies, many of these agents are associated with significant toxicity, as well as high costs. A retrospective cross-sectional study of 404 breast cancer patients was performed to determine the effect of β-blocker usage on tumor …

Exploring Aging Using The Selection, Optimization, And Compensation (Soc) Framework In Conjunction With Kinematic Gait And Verbal Fluency Task Analysis In Healthy Adults, Emily Ann Chavez

Open Access Theses & Dissertations

This multi-study dissertation examined dual-task performance in young and middle-aged adults using verbal fluency tasks (VFT) during different walking scenarios (baseline, performing a VFT, walking narrowly, and performing a VFT while walking narrowly) as well as the Selection, Optimization, and Compensation (SOC) model. Thirty adults (15 young adults (YA; 19-44 years) and 15 middle-aged adults (MA; 45-65 years) participated in this study. Overall, there were no significant differences between groups when data was examined in short (means of means approach) and long-form (incorporating all data), when analyzing clustering and switching strategies, gait speed variability, or dual-task costs. Overall, these three …

Characterization Of Developmental Phenotypes In Zebrafish With Mutations In Mmachc, Briana Elise Pinales

Open Access Theses & Dissertations

Methylmalonic aciduria and homocystinuria, CblC type (cblC) syndrome (MIM 277400) is a genetic disorder resulting from a mutation in the MMACHC gene. This gene plays a crucial role as a chaperone in the conversion of vitamin B12 into its active form, which is essential for proper cellular metabolism. cblC syndrome is heterogenous by nature, primarily attributed to the extensive damage it causes across multiple bodily systems. In cases of early onset of cblC syndrome, patients may exhibit a diverse range of clinical symptoms including difficulties with feeding, dysmorphic features, microcephaly, brain abnormalities, hypotonia, developmental delays, and seizures. The study of …

Interfacial Interactions Between Engineered Nanoplastics And Biological Systems: Towards An Atomic And Molecular Understanding Of Plastics- Driven Cellular Dyshomeostasis, Afroz Karim

Open Access Theses & Dissertations

The persistent presence of micro (nano) plastics in our environment has raised concerns regarding potential health risks associated with human exposure. With the extensive use of plastic materials and the widespread consumption of plastic-contaminated food items, two types of microplastics, polystyrene (PS) and polymethylmethacrylate (PMMA), have attracted increased attention. While the adverse effects of microplastics on animals and marine life have been extensively studied, their potential impact on human health remains largely unexplored. Specifically, the interaction between microplastics and biomolecules within the human body and their effect on human health have yet to be comprehensively investigated. This dissertation study focuses …

Development Of Synthetic Glycobiomarkers For The Follow-Up Of Chagas Disease Chemotherapy And Serological And Molecular Assays For Evaluation Of Trypanosoma Cruzi Infections In The U.S-Mexico Border, Igor L. Estevao

Open Access Theses & Dissertations

Chagas disease (CD), caused by the protozoan parasite Trypanosoma cruzi, affects 7-8 million people worldwide. Lately, the disease has been spread to nonendemic countries and regions, like the U.S. and Europe. The disease can be divided into two phases: the acute and chronic phases, which continue for years or even decades. There are two available drugs for CD treatment: benznidazole (BNZ) and nifurtimox (NFX). These drugs are highly effective in the acute phase but less efficient in the chronic stage. Other limitations of these drugs are their toxicity, leading to serious adverse events and premature treatment termination. Newer clinical trial …

Evaluation Of The Efficacy Of Synthetic Glycovaccines Against Both Murine Acute Chagas Disease And Cutaneous Leishmaniasis, Colin D. Knight

Open Access Theses & Dissertations

Chagas disease (CD) and cutaneous leishmaniasis (CL) are neglected tropical diseases caused by the protozoan trypanosomatids, Trypanosoma cruzi and Leishmania spp., respectively. There are approximately 6-8 million people infected with T. cruzi worldwide and ~300,000 people in the US. Between 700,000 and 1.2 million new cases of CL occur worldwide yearly. The approved chemotherapies for both diseases are partially effective and may cause serious adverse events, resulting in premature treatment interruption. Moreover, no effective vaccine for either disease is available. Therefore, developing a vaccine that would provide effective cross-protection against both diseases would provide a cost-effective alternative to the existing …

Proteomic Analysis Reveals Fkbp51 And Fkbp52 Interactors Implicated In Androgen Receptor-Mediated Castration Resistant Prostate Cancer, Olga Soto

Open Access Theses & Dissertations

Aberrant signaling mechanisms by the Androgen Receptor (AR) are attributed as the main culprits for the initiation and progression of prostate cancer (PCa). Due to its dependence on androgens, research efforts have focused on developing strategies to directly target androgen-mediated receptor activity. However, given the recurrence and treatment resistance of PCa despite androgen targeted therapies, recent efforts have shifted to find novel targets against the disease. These efforts include further revealing the molecular components and their mechanisms underlying AR signaling in both normal and disease physiological settings. Hence, our lab's work is focused on characterizing and targeting molecular chaperones that …

Functional Characterization Of The Human And Murine Schlafen Family Group Iii, Carlos A. Valenzuela

Open Access Theses & Dissertations

The Schlafen (SLFN) family of proteins are known for being encoded by interferon stimulated genes. The family is divided into three groups (I, II, III), for which the largest in size belong to the subgroup III. In humans, group III has the most members (SLFN5, SLFN11, SLFN13 and SLFN14); there is no member of group I and only one member of group II (SLFN12). All human SLFNs belonging to group III have been reported to impair viral protein expression or infection across a variety of viruses. The antiviral function is mediated in SLFN11 and SLFN13 by their tRNase activity, and …

Growth Of Purple Sulfur Bacteria Allochromatium Vinosum On Solid Phase Metal Sulfides As Sulfur And Electron Sources, Hugo Alarcon

Open Access Theses & Dissertations

Purple sulfur bacteria (PSB) are photosynthetic microorganisms known for their vital roles in geochemical cycles, especially the sulfur cycle, within anoxic photic environments. PSB are also key contributors to the nitrogen, carbon, and oxygen cycles. This study focuses on the autotrophic growth of Allochromatium vinosum, a model strain of PSB, that utilize solid-phase metal sulfides (MS) as both sulfur and electron donors. Through characterizing the growth profiles of A. vinosum on pyrite (FeS2), nickel sulfide (NiS), and iron monosulfide (FeS) nanoparticles, respectively, and investigating the bacteria-MS interaction mechanisms, this work expands our current knowledge of the metabolic capabilities and flexibility …

The Importance Of Soil Carbon In Large-Scale Shrub Removal Practices In The Chihuahuan Desert, Kathleen Schaeffer

Open Access Theses & Dissertations

Shrub encroachment is a worldwide phenomenon that affects multiple biomes at different ecological and anthropogenic levels. In dryland ecosystems, shrub encroachment is a noted concern amongst land managers, as it can lead to a loss of soil resources and biodiversity. To mitigate the negative effects of shrub encroachment in Drylands, land managers can implement large-scale shrub removal practices. These land restoration practices can shift landscapes to novel ecosystems, where resulting plant communities can vary following treatments. Grass recovery or increasing herbaceous cover is often a primary goal of these treatments, however predicting which sites may show higher grass responses to …

Increases In Uvr Exposure: Local Adaptation Of A Bdelloid Rotifer, Maribel J. Baeza

Open Access Theses & Dissertations

Aquatic species living in ephemeral habitats without a continual influx of dissolved organic carbon (DOC) are at increased risk of the effects of ultraviolet radiation (UVR) as the climate changes. Climate change is predicted to cause changes in DOC, some habitats will experience extended periods of drought and reduced input from DOC sources, and other environmental features that increase UVR reaching aquatic habitats. UVR can cause damage to cellular structures and biomolecules such as DNA, proteins, and lipids. The pigmented bdelloid Philodina sp. (Philodina) found in rock pools in the Chihuahuan Desert naturally experiences high UVR, yet it appears to …

Exploring Undergraduate Research Experiences And Perceptions Of Responsible And Ethical Conduct Of Research (Recr) Education In The Biological Sciences And (Bio)Chemistry Disciplines, Bernice Justina Caad

Open Access Theses & Dissertations

Increasing calls to reform undergraduate (UG) education within science, technology, engineering, and mathematics (STEM) disciplines have emphasized the importance of early exposure to responsible and ethical conduct of research (RECR) education. Historically, RECR has primarily been presented at the post-baccalaureate level, leaving many students without a foundational understanding of what responsible research ethics entails during the course of their undergraduate experience. Over the last decade, course-based undergraduate research experiences (CUREs) have emerged as a promising platform to establish expectations of responsible and ethical conduct through greater accessibility and inclusivity, starting at the freshman level. Interestingly, few studies have examined how …

Diversity And Lifestyle In The Rotifera, Patrick D. Brown

Open Access Theses & Dissertations

Broad questions regarding community assembly and lifestyle evolution remain unanswered. To answer these questions I used rotifers, common primary consumers present in inland waters. Rotiferan presence in nearly all freshwaters makes them an ideal study system to address questions of metacommunity ecology. Additionally, rotifers possess diverse lifestyles, including sessile, swimming, colonial and solitary forms, allowing them to be used as models of lifestyle evolution. In Chapter 1, I address metacommunity ecology by focusing on inland waters of the Chihuahuan Desert as a study system and investigated rotifer community assembly therein through two published works, Brown et al., 2020 and 2021. …

X-Ray Crystal Structure Of E399q,E708q Ecm16 Double Mutant, Gileydis Guillama

Open Access Theses & Dissertations

The use of antibiotics has undoubtedly been a boon for humanity in combating infections and microbial threats. However, their widespread utilization has contributed to the emergence and spread of antibiotic resistance, which now poses a significant public health challenge. Streptomyces bacterium, produce diverse secondary metabolites with antibacterial, antifungal, antiviral, antitumoral, and immunosuppressant activities. Among these compounds is echinomycin, a nonribosomal peptide antibiotic synthesized by Streptomyces lasalocidi, which inhibits DNA replication and transcription by intercalating the DNA duplex at CpG steps. A gene called ecm16 was identified in the echinomycin biosynthetic gene cluster, which provides echinomycin self-resistance. Ecm16 recognizes DNA duplexes …

Structural Study Of Lsd13 And Lsd14 Type I Modular Polyketide Synthases From The Lasalocid A Biosynthesis Pathway, Dayan Viera

Open Access Theses & Dissertations

Bioactive natural products often possess a complex structure and have a large size which make their chemical synthesis highly challenging. To overcome this challenge, we are developing a biosynthetic method for production of natural products and their analogs. This technology is expected to decrease the synthesis time from years to weeks and reduce the cost of drug production by multiple orders of magnitude. We are investigating the biosynthesis pathway of lasalocid A, an anticancer antibiotic, to develop this technology. Specifically, we aim to characterize the enzymes structurally and biochemically in this pathway, thus paving the way for their rational engineering. …

Immunoreactivity Of The Serotonin-Like And Fmrf-Amide-Like Nervous Systems Of Four Gnesiotrochan Rotifers, Robert Neil Walsmith

Open Access Theses & Dissertations

Reorganization of the nervous system during metamorphosis is a common phenomenon across taxa (species through phyla). In phylum Rotifera, sessile species belonging to the superorder Gnesiotrocha metamorphose from free-swimming larvae into sessile adults. Once mature, gnesiotrochan rotifers display an intricate corona or infundibulum associated with lifestyle modalities and feeding behaviors. Here, I examine serotonin-like immunoreactivity (SLIR) and FMRF-amide-like immunoreactivity (FLIR) of the gnesiotrochans Lacinularia flosculosa, Collotheca ferox, and Acyclus inquietus with a focus on life stage and sex. Based on previous research, I hypothesize that 1) innervation of the larval nervous system will vary according to the lifestyle constraints observed …

Merging Clinical And Genomic Data In Patients With Acute Leukemia For Downstream Analysis, Amanda Bataycan

Open Access Theses & Dissertations

The purpose of this study is to integrate multiple sources of information from patients with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) to construct organized datasets that would enable downstream bioinformatics and statistical analyses of the patientsâ?? survival status and overall survival times in relation to their demographic, clinical, and genomic mutation profiles. With NIH Genomic Data Commons as the primary data resource and cBioPortal as the access portal, datasets on 149 and 603 unique patients with AML and ALL, respectively, were obtained. Python scripts were written to compile individual patientsâ?? single nucleotide variant (SNV) data files into …

The Ecological Effects Of Nitrogen Enrichment In Aridlands, Jennifer Holguin

Open Access Theses & Dissertations

Anthropogenic nitrogen (N) deposition is one of the most prominent factors driving global change. Across the globe, N deposition has driven major changes in terrestrial ecosystems, such as declines in plant biodiversity, enhanced exotic plant growth, and changes to biogeochemical processes involved in carbon and nutrient cycling. While noteworthy effort has been put forth to investigate the effects of N deposition on terrestrial ecosystems, a disproportionate number of N addition studies have been conducted in temperate mesic systems. Thus, we lack a holistic and mechanistic understanding of how N deposition impact aridland ecosystems. Additionally, our predictions of the effects of …

Functional Analysis Of The Gamma-Aminobutyric Acid Type A Receptor Subunit Alpha-1 (Gabra1) Gene During Zebrafish Development., Nayeli Gabriela Reyes-Nava

Open Access Theses & Dissertations

The GABRA1 gene encodes for the alpha-1 (α1) subunit of the Gamma-Aminobutyric acid type A receptor (GABAAR), which are the primary modulators of synaptic inhibition in the central nervous system (CNS). Alpha-1 subunits are essential for maintaining the normal function of native receptors and contribute to over 60% of all GABAARs in the CNS. Remarkably, a broad spectrum of neurodevelopmental and epilepsy-associated disorders have been linked with mutations in the GABRA1 gene. However, the developmental, behavioral, and molecular mechanisms underlying GABRA1-associated epileptic disorders remain to be fully understood. Hence, the overarching goal of this dissertation is to investigate the behavioral …

Using Machine Learning And Distributed Hydrologic Modeling To Predict Soil Texture, Surface Soil Moisture And Evapotranspiration In Jornada Experimental Range, Southwestern U.S., Jorge Andres Mayo

Open Access Theses & Dissertations

In water-limited ecosystems, detailed knowledge of the soil, vegetation, and atmosphere interactions is critical to understand the processes that control the partitioning of energy, water fluxes, and biogeochemical cycles within the critical zone. This Master's thesis is divided into two main contributing sections. The first, is on the use of machine learning to reconstruct missing soil type information, and the second, on the calibration and validation of a physically-based distributed hydrological model to estimate soil moisture and evapotranspiration within the Jornada Experimental Range of the U.S. in southern New Mexico. For the first contribution, three explainable, shallow machine-learning techniques are …

Analysis Of The Electrostatic Characteristics Of The Zika Virus Capsid Using Computational Methods, Cassandra Guadalupe Del Rio De Avila

Open Access Theses & Dissertations

Zika virus (ZIKV) is a flavivirus that is usually transmitted through the bite of infected mosquitoes. This virus can cause a variety of neurological disorders, the most common being Guillain-Barré syndrome in adults. Moreover, it is of great concern in pregnant women, since can cause deformities in the brain and other organs of newborns.Studying the structural characteristics of the virus during its mature and infectious phase can provide crucial information on the mechanisms by which it enters and replicates within host cells, as well as its evolution, transmission, and interaction with other living organisms. The symmetric pattern present in the …