Digital Commons Network^™

Defining The Role Of Spxa1 And Spxa2 In Group A Streptococcus (Gas), Gretchen Anne Morrison

Dissertations and Theses (Open Access)

Group A Streptococcus (GAS) is a human-restricted pathogen whose global incidence has surged in the post-COVID era. The ability of GAS to shift from a colonizing to invasive phenotype depends on coordinated virulence gene regulation in response to host-imposed stressors. The paralogous global transcriptional regulators, SpxA1 and SpxA2, have emerged as central mediators of these adaptive responses; however, the mechanisms by which these regulators influence both global gene regulation in direct response to external stresses and the host response as a result of regulatory changes remain incompletely understood. Using an integrated multi-omic approach, we define the distinct yet interconnected regulatory …

Regulation Of Müllerian Duct Mesenchyme Transcription During Mammalian Sex Differentiation, Haowen Li, Richard R Behringer, Rachel D Mullen

Dissertations and Theses (Open Access)

Sp7/Osterix (Osx) encodes a zinc-finger transcription factor of the Specificity-protein family discovered by Nakashima et al. at the MD Anderson Cancer Center. While primarily recognized for its role in osteogenesis, Osx has also been implicated in mammalian reproductive development, particularly in male sex differentiation, where Müllerian Duct (MD) regression occurs, mediated by anti-Müllerian hormone (AMH) signaling. AMH-induced regression signals are transduced by the mesenchymal tissue surrounding the ductal structure, known as the Müllerian Duct mesenchyme (MDM). It was discovered that AMH signaling is necessary and sufficient for driving Osx expression in MDM. A previous transgenic mouse reporter …

Oxidative Stress Mediated Glutamate Release And Nmda Receptor-Dependent Synaptic Remodeling In Radiation-Induced Cognitive Dysfunction, Thanh Lam

Dissertations and Theses (Open Access)

In children younger than 14 years old, the brain and other parts of the central nervous system are the most common sites for solid tumors. Radiotherapy is an effective treatment for central nervous system (CNS) tumors. However, it often causes a progressive decline in cognitive functions, which is especially devastating for pediatric patients. Although post-mitotic neurons are generally considered resistant to radiation-induced immediate cell death, ionizing radiation causes complex neurochemical and structural changes that damage synaptic integrity. In this study, we examined the molecular cascades following a 10 Gy radiation dose applied to mouse cortical neurons. We found that radiation-induced …

A Comparison Of Survival, Growth, And Stress Resilience In Three Different Lineages Of The Pacific Oyster (Crassostrea Gigas) Farmed On The California Central Coast, Victoria F. Hanshaw

Master's Theses

Aquaculture of Pacific oysters on the US West Coast is routinely impacted by seasonal unexplained mortality events. To better understand these large-scale mortality events in oyster aquaculture, shellfish growers and scientists in California have partnered together to conduct comparative, multi-estuary farm trials of discrete Pacific oyster (Crassostrea gigas) lineages. In this thesis we investigate how the more recently imported Midori lineage performs compared to the historically used Miyagi lineage, as well as a Hybrid (Midori x Miyagi) lineage. As part of a 7-month long field study from April-November of 2024 in Morro Bay and Tomales Bay, California, we evaluated …

From Genes To Streams: Mitochondrial Approaches To Population Monitoring Of The Santa Ana Sucker Catostomus Santaanae, Mariana Antonio

Electronic Theses, Projects, and Dissertations

This study was developed to use aquatic environmental DNA (eDNA) as a tool to detect the presence of the Santa Ana sucker (Catostomus santaanae), a federally threatened fish species, across the Santa Ana River in Southern California. Environmental DNA is any genetic material that an organism sheds into the environment. We can get an idea of what aquatic species are present when sampling water at a given site. We sequenced the complete mitochondrial genome (mitogenome) of the Santa Ana sucker and designed custom DNA primers to improve eDNA detection accuracy. These primers were selected based on high genetic …

Testing P300-Based Biometric Authentication Paradigms, Jordan Razzak

Electronic Theses and Dissertations

Bench research suggests that P300 amplitude is greater in response to self-relevant stimuli compared to familiar stimuli. This effect could enable a novel method of biometric authentication based on the self-relevant P300. This dissertation aims to: (1) determine the optimal presentation paradigm for leveraging self-relevance in P300-based biometric authentication, and (2) investigate P300 responses from self-relevant stimuli versus stimuli learned over the course of a week.

Two presentation paradigms were compared – rapid serial visual presentation (RSVP) and matrix presentation (MP). Participant-specific RSVP and MP classifiers were trained by applying stepwise linear discriminant analysis to data collected during presentations of …

The Influence Of Habitat And Individual Specialization On Mountain Lion (Puma Concolor) Hunting Strategy In A Multi-Prey System, Hannah B. Klugman

All Graduate Theses and Dissertations, Fall 2023 to Present

There is a growing recognition that animal species considered generalists (having a broad and varied diet), are actually specialists, a collection of individuals with different preferences and strategies known as specializations. The diet of a specialist depends on the variety and quantity of available food options, and their own ability to take what they need. Mountain lions (Puma concolor) are known for their ability and tendency to hunt large prey, such as elk (Cervus canadensis) and mule deer (Odocoileus hemionus), but despite the fact they overlap with other potential large prey, like feral horses …

Secure Agricultural Futures: Re-Defining And -Imagining Agricultural Water Landscapes In The Us West, Britta L. Schumacher

All Graduate Theses and Dissertations, Fall 2023 to Present

Aridity is swiftly becoming the US West’s new normal. As agricultural communities adjust to persistent growing-season scarcity, they find their livelihoods under increasing threat. This points to the urgency of finding paths toward more secure water futures. A piece of this future puzzle includes water (re-)distribution – taking excess from one place and delivering it to another in need. To begin thinking about (re-)distribution, this dissertation engages with three mixed-methods and multiscale studies. The first study pairs county-level data across the 11 westernmost US states with survey data collected from individual producers in Utah to assess past and current trends …

Advancing Management Strategies For Two Promising Mason Bee Species (Osmia Ribifloris And Osmia Bruneri) For Berry Pollination, Miranda L. Jones

All Graduate Theses and Dissertations, Fall 2023 to Present

Bee management can broadly refer to human manipulation of one or multiple parts of a bee’s lifecycle. Managing honey bees, commonly referred to as beekeeping, is responsible for providing most pollination for global food crops. However, using more than one bee species for crop pollination can have many benefits. Benefits include better crop pollination and insurance in case one bee species underperforms or its population collapses. Some bees within the genus Osmia are already widely managed for crop pollination because their developmental lifecycle allows bee managers to readily deploy pollinating bees in sync with varying crop blooms, and for certain …

Investigating Recruitment Bottlenecks Of Juvenile Native Fish In The Colorado River Basin, Utah, Anna R. Amidon

All Graduate Theses and Dissertations, Fall 2023 to Present

The first year of life is a vulnerable period for most fish species. Whether young fish survive this early stage determines how many individuals eventually survive and grow into reproductive adults, a process called recruitment. In desert rivers like the Colorado River Basin, native fish evolved alongside extreme natural conditions but now face additional pressure from drought and water storage infrastructure, which alter the shoreline habitats on which young fish depend. Long-lived, migratory native species with complex life cycles are especially vulnerable. We used four decades of monitoring data from the Upper Colorado River Basin to evaluate whether young-of-year (YOY, …

Seizure Susceptibility And Morphological Analysis Of A Missense Mutation In Hcfc1a Protein, Jose Manuel Fabela

Open Access Theses & Dissertations

Missense mutations in the HCFC1 gene cause methymalonic acidemia with homocystinuria cblX type (MIM#309541). cblX is an X-linked disorder that is associated with multiple phenotypes such as metabolic defects, failure to thrive, intractable epilepsy, facial dysmorphia, movement disorders, and intellectual disability. The mechanisms underlying these phenotypes are not completely understood. Here we used a zebrafish germline mutant allele (hcfc1aco64/co64) to study seizure susceptibility and adult brain structural malformations. Previous studies have established neural progenitor cell defects and hypoactive mechanistic target of rapamycin (mTOR) in this allele. Given the known role of mTOR in seizure phenotypes, we hypothesized that missense mutation …

Expression Levels Of Heat Shock Protein 72 And Their Correlation With Biomarkers Of Renal Function Among Hispanic Construction Workers Exposed To Ambient Heat In El Paso, Texas, Maria Fuentes

Open Access Theses & Dissertations

Heat shock proteins (HSP) are intracellular molecular proteins that are upregulated in response to cellular stress, including heat exposure. Through their protective functions, HSP help maintain protein structure, prevent protein denaturation, and preserve cellular homeostasis during states of physiological stress. Because of their cytoprotective properties, HSP have emerged as potential biomarkers for detecting early signs of tissue injury and predicting clinical outcomes associated with heat related illnesses (HRI), including acute kidney injuries (AKI). AKI is a leading cause of hospitalizations due to heat stress exposure and heat stroke. In the absence of early detection and effective therapeutic interventions, AKI may …

Parametric Assessment Of Nicotine Vapor Self-Administration In Rats, Tiffany Alexandra Gonzalez-Gutierrez

Open Access Theses & Dissertations

The increasing prevalence of electronic cigarette (e-cigarette) use among adolescents highlights the need to identify factors that promote nicotine vapor use in populations most susceptible to its long-term consequences. This requires translationally relevant animal models of nicotine vapor self-administration (VSA). Accordingly, the goal of this dissertation was to evaluate 2 key factors hypothesized to influence nicotine VSA in rats, including age and e-liquid vehicle composition. Given recent mandates on studying sex as a biological variable, the present work included both female and male rats. Aim 1 compared VSA behavior during adolescence (adolescent-onset) or adulthood (adult-onset) in groups that received vapor …

Tissue-Specific And Sex-Dependent Microbiome Structure In East African Cattle Ticks (Amblyomma Gemma And Rhipicephalus Pulchellus) And Their Bovine Hosts, Dennis Getange, Samson Mukaratirwa, Rua Khogali, Epaphrus Yuko, James Kabii, Joel L. Bargul, Jandouwe Villinger

All Peer-Reviewed Publications

Ticks and their vertebrate hosts share intimate ecological interactions that shape microbial community composition, with implications for tick fitness and pathogen transmission. However, the extent and specificity of tick–host microbial interactions remain poorly understood, particularly in East African tick species. Here, we characterised microbial communities across multiple tissue types from two economically important tick species (Amblyomma gemma and Rhipicephalus pulchellus) and their shared bovine host using 16S rRNA V1-V2 gene sequencing. We profiled haemolymph, midgut, salivary glands, and gonads from individual ticks (25 Am. gemma and 8 Rh. pulchellus), alongside 12 bovine blood samples. Microbiota were dominated by Proteobacteria, Firmicutes, …

An Analysis Of Mating Strategies In Rotifers Inhabiting Temporary Habitats, Ariel Bollinger

Open Access Theses & Dissertations

Reproduction is critical for organisms inhabiting ephemeral aquatic habitats where desiccation risk favors rapid and successful mating. Monogonont rotifers rely on sexual reproduction to produce diapausing eggs that withstand harsh conditions. I investigated how mating behaviors vary among populations of five rotifer species based on the hydroperiod of their habitat: Epiphanes brachionus and E. chihuahuaensis were sampled from habitats with short (SH) and long (LH) hydroperiods; Euchlanis dilatata was collected from a short (SH) and a permanent habitat; and Plationus patulus and Sinantherina socialis were collected from a long (LH) and a permanent (Perm) habitat. I hypothesized that SH populations …

Blue Crab Reproductive Output And Phenology In A Changing Climate, Blaise Rohan

Master's Theses

Globally, ecosystems are experiencing rising temperatures due to climate change, with potential consequences for reproductive investment and timing in many species. Blue crabs, Callinectes sapidus, support valuable commercial fisheries throughout the U.S. Atlantic and Gulf coasts, and understanding variation in reproductive output has important management and conservation implications. This study examined two components of blue crab reproduction: (1) reproductive investment across populations spanning multiple latitudes (New York, New Jersey, North Carolina, Mississippi, and Texas), using a space-for-time substitution to assess the effects of varying thermal regimes on fecundity and egg quality, and (2) spawning phenology in North Carolina from …

Harnessing Kenyan Aquaculture Through Social Media: Impacts, Challenges And Strategic Directions, Domitila Kyule, Jonathan Munguti, Mavindu Muthoka, Esther Magondu, Menaga Meenakshisundaram, Chrysantus M. Tanga, Kevin Obiero, Cecilia Githukia

All Peer-Reviewed Publications

Aquaculture is increasingly important for food, nutrition and livelihoods in Kenya, but the sector still faces persistent constraints in extension delivery, farmer learning, input access, market coordination and information reliability. This review examines how social media and related digital communication tools are shaping aquaculture development in Kenya, with attention to impacts, challenges, governance needs and strategic directions. A systematic literature review of studies and institutional sources published between 2015 and 2025 was conducted. The search identified 388 records, of which 45 sources were included in the final synthesis after screening, eligibility assessment and quality appraisal. Because the evidence was heterogeneous, …

Technological Behaviour Of Pellets Containing Dried Green Crop, Christian Furll

IGC Proceedings (1977-2023)

Pelleted dried green crop presents essential advantages compared to chaff and meal as processing forms. Normally, the solidity of the pellets does not exceed the values required by animal feeding. Abrasion resulting from turnover processes is at present too high, particularly for the discharge of bins. Belt conveyors, vibrating conveyors, and bucket elevators are suitable to convey pellets. Storage of pellets over long periods has to be done by respecting prescribed climate conditions. Zones with excessive portion of abraded par­ticles in the storing pile are a preferred cause for self-heating. Slit-type dosing units as well as dosing units equipped with …

The Production Of Dry Feeds From Straw And Green Forage In The Gdr, Fritz Berg

IGC Proceedings (1977-2023)

In the GDR, at present about 9% of the feed energy requirement of cattle is covered by dry feeds, above all mechanically processed and chemically treated straw as well as dried green forages. This share is expected to rise to 15 % in forthcoming years. On the basis of technological fundamentals devised by animal nutritionists, corresponding production processes are being developed and perfected. They allow to convert the feedstuffs into a physical and chemical form favourable to high intake; in addition, the feeding value of high-fibre feedstuffs is improved. In this way, the feedstuffs are fed in favourable com­bination as …

Etiology And Control Of Total White Ears In Grass Stands For Seed Production, Theo Wetzel

IGC Proceedings (1977-2023)

The total white ears is one of the major diseases of forage grasses grown for seeds. Heavy losses are common in fescue species and in Poa pratensis L. While non-parasital factors can be neglected as a cause of the white ears, the tarsonemid mites, especially the species Siteroptes graminum (Reuter) and Steneotarso­nemus spirifex (Marchal), are major animal pests. Limiting the period of use of such seed grass stands to a maximum of 2 years and the application of lindane and oleo-parathion prep­arations have proved effective control meas­ures.

Irrigation With Sewage -An Effective Procedure For In­Creasing The Yield Performance Of Grassland As Well As For Protecting Inland Waters Against Pollution, V M. Novikov, N A. Kovaleva, V P. Sayapin, L F. Mikheeva, M I. Demina

IGC Proceedings (1977-2023)

The utilization of sewage for irrigation pur­poses is an effective procedure for increasing the yield performance of grassland as well as for protecting inland waters against pollution. Compared with irrigation only during the growing season, all-season use of sewage is more effective in increasing forage production and reducing both the quantity of sewage diverted into inland waters and the deficit of irrigation water. By way of science-based choice of the irri­gation regime, the perennial forage plant spe­cies, and their kind ofutilization, 8.0-10.0 tons and more of high-quality dry matter can be obtained per hectare, with 6,000-7,000 m3 of sewage being …

Recommended Values For Dimensioning And Designing Sprinkler Irrigation In Industrialized Forage Plant Produc­Tion In The Gdr, Klaus Schwarz, Dieter Roth

IGC Proceedings (1977-2023)

With the transition to industrialized crop and animal production in the GDR, sprinkler irrigation of field forage plants and grassland, above all with sewage water and clean water +slurry mixtures, is becoming more and more important. It gets increasingly concentrated on field grass and grass/clover stands. The supple­mental water requirement is 210 to 270 mm/ year in case of clean-water sprinkling and up to 400 mm/year if sewage water is used. The hydro-modulus of the irrigation plants is be­tween 1.2 and 1.6 m3 /h/ha, depending on the simultaneity factor. In order to attain the required water quantity per unit of …

Effect Of Increasing Levels Of Phosphorus And Three Types Of Soil On Glycine Wightii In Cuba, T Ruiz, J R. Ayala

IGC Proceedings (1977-2023)

A factorial design with 4 replications was used to study the effect of increasing levels of phosphorus (0, 30, 60, 90, 120, and 150 kg P/ha) in three tropical soils (red, brown, and gley) on Glycine wightii in a glasshouse exper­iment. The highest DM yields were achieved with the brown soil. Levels of 30 kg P/ha always increased yields in all the soils used (P < 0.01) but no differences were found with higher P applications. In general, P in plant tops was not related with the levels of P applied. K tended to decrease as the levels of phosphorus increased. None of the treatments used in­fluenced Ca and Mg. A similar work is suggested to be carried out in the field.

Effect Of Nitrogen-Potassium Levels On The Yield Of Guinea Grass (Panicum Maximum Jacq.), G Crespo, J Perez

IGC Proceedings (1977-2023)

The effects of combining levels of 0, 150, 300, 450, 600, and 750 kg K/ha/year and 0, 300, 600, 900, 1200, and 1500 kg N/ha/year on the DM yield and NK contents of Guinea grass were studied in a latosolic soil, not K-deficient, by using a factorial design with two replications. The experiment lasted 2 years. During the first 6 months there was no response to K appli­cations and yield only increased with increasing N fertilization (4.3 t/ha with N0 up to 12.8 t/ha with 60 kg N/ha). For the rest of the experi­ment it was found necessary to apply …

The Effect Of Nitrogen Fertilization And Age Of Regrowth On The Chemical Composition Of Coast Cross No. 1 Bermuda Grass (Cynodon Dactylon), R Herrera, N Ramos

IGC Proceedings (1977-2023)

The effect of nitrogen fertilization (0, 50, and 100 kg/ha) and regrowth age from 1 to 12 weeks on the chemical composition of Coast Cross cv. No. 1 bermuda grass was studied during the dry season using sprinkler irrigation. Crude protein tended to decrease with age, increasing with the N levels up to 20 % with 100 kg N/ha. Total soluble carbohydrates (TSC) were in­fluenced by age (P < 0.001); the same did not hold true for N. The adjustment of regres­sion equations for lignin and cellulose showed increasing values with respect to age. In vitro DM digestibility (IVDMD) showed signifi­cant differences (P < 0.001) only when 100 kg N were applied (50.46%). The two other levels did not differ between them, being 43.45 and 46.11 % for 0 and 50, respectively. The highest value obtained was of 62.07 % in the fourth week with 100 kg N. From the 8th week a sharp trend to decrease was found for all the treatments. Suggested is the use of 100 kg N/ha every twelve weeks and cuts between the fifth and sixth weeks in order to obtain good­quality pastures.

The Intensification Of Grass Production Through Nitrogen Fertilization, And The Nitrate Problem, Klau Ebert, Henrich Koriath, Gunter Rinno

IGC Proceedings (1977-2023)

Two-year pot and five-year field tests with increasing nitrogen doses revealed an increase in the nitrate content of forage grasses. In the pot tests the content of 0.25 % N03-N in the dry matter, which is safe in animal nutrition, had by far been exceeded. In the field tests the· nitrate content increased more slowly for the average of the tests and did not reach this limit when giving 140 to 240 kg N/ha. In single cases this value had, however, already been reached when giving 100 kg N/ha. By selecting grass species with a lesser tendency to nitrate accumulation, …

Effect Of The Nitrogenous Fertilizer Level On The Performance Of Bulls Grazing On Common Pangola Grass (Digitaria Decumbens Stent.) At Two Stocking Rate Levels, L R. Valdes, A Perdomo

IGC Proceedings (1977-2023)

A study was made of the effect of nitrogenous fertilization and stocking rate on the live weight gain and the composition of the carcass of bulls grazing on pangola grass. Treatments were five nitrogen levels: 80, 160,240, 320, and 400 kg/ha/year, each with stocking rates of 4 and 6 animals per hectare. No nitrogen level effect was found during the rainy season, while in the dry season the major levels of 240 kg/ha produced greater gains of live weight (P < 0.001). Animals that were submitted to stocking rates of 6 animals/ha gained less and the production per hectare was significantly greater (P < 0.01 ). Animals of higher levels of nitrogen had more adipose carcasses. The results suggest that the increased levels of nitrogen applied in the rainy period in­fluenced the growth of grass and the animals during the succeeding dry period.

Effect Of High Nitrate Fertilization On The Yield And Biological Value Of Grasses Tested By Common Vole, Slawomir Pronczuk, Janina Gnat, Tadeusz Szuperski

IGC Proceedings (1977-2023)

The effect of different fertilization doses ( 4 x 60, 4 x 120, and 1 x 480 kg N/ha) on the yield of grasses and their basic chemical composition as well as on the growth efficiency and health of animals fed those grasses was studied. Yield of grass during three following years was higher from the fields fertili_zed 4 x 120 and 1 x 480 kg N/ha, when compared to 4 x 60 kg N/ha. No differences were found be­tween 1 x 480 kg N/ha and 4 x 120 kg N/ha. Growth ·efficiency of the common voles which were fed …

Forage Production With Intensive Fertilization And Sprinkler Irrigation For The Supply Of A Dairy Farm Working On An Industrial Scale, Gerhard Weinreich, Wolfgang Richter, Jurden Gellrich, Manfred Meyer

IGC Proceedings (1977-2023)

The development and the results of the Dedelow cooperative farm for crop production testify the successful agricultural policy pursued in the GDR. Intensification measures, such as mecha­nization, fertilization and irrigation, brought about a stable growth of production and form the basis for further economic success. At the same time it becomes obvious that cooperative farmers and farm workers have developed in a way that enabled them to master the processes prevailing in large-scale crop and animal pro­ductions from the technical as well as organi­zational points of view, even at a growing in­tensification of production.

The Effectiveness Of Mineral Fertilizers On Meadows In The Western Ukraine, V D. Gorb, M T. Yarmolyuk

IGC Proceedings (1977-2023)

In the western parts of the Ukrainian SSR, the effectiveness of mineral fertilization of culti­vated pastures depends on the type of soil, the forage plant stand, and the rates of fertilizer applied. Without irrigation, nitrogen fertili­zation on a slightly loamy meadow soil was highly effective. The yield increment per 1 kg N applied at rates of 60-240 kg/ha was 25- 1 7 kg in the case of dry matter yields of 7.45-10.14 t/ha. On highly acid medium-loamy pseudogleyed soddy podzolic soils, cultivated pastures gave much lower dry matter yields, namely 2.06-4.27 t/ha. Nitrogen fertilization is highly effective at higher rates …