Life Sciences Commons^™

Stress Response Mechanisms Of Listeria Monocytogenes, Oindrila Paul

Dissertations

Listeria monocytogenes is a Gram-positive, facultative intracellular food-borne pathogen that causes the disease listeriosis. In order to establish an infection, L. monocytogenes must survive multiple stressors encountered within the gastrointestinal tract, including alterations in pH, bile, salt, and oxygen availability. This dissertation focused on understanding the stress response of L. monocytogenes to bile. Bile acts as a bactericidal agent by disrupting the membrane integrity and causing instability to macromolecules like DNA. Thus, a bacterium must be able to maintain its membrane architecture, composition and integrity.

Often times, bacteria will modulate their fatty acid composition in the membrane to cope with …

Ecological Stoichiometry: What Role Does It Play In The Competition And Spatial Distribution Patterns Of Aedes Albopictus And Aedes Aegypti?, James Deerman

Master's Theses

Ecological stoichiometry is the balance of chemical substances within animal bodies through interactions and processes within their ecosystem. Though relatively underexplored, it provides a wealth of information linking interactions across different levels of organization. Detritus is the base of the food web within the small aquatic ecosystems occupied by the mosquitoes Aedes albopictus and Aedes aegypti. Nutrient content of detritus varies, but it can have a negative effect on mosquito growth and survival if nutrient thresholds are not met. I investigated nutrient environments and species abundance in cemetery vases in New Orleans, LA to assess detrital heterogeneity and its …

Effect Of Reinforcement Selection On Mate Selection Rates Of Gambusia Affinis And Gambusia Holbrooki, Molly Stephens

Honors Theses

This study was conducted in order to investigate the effects that reinforcement selection has on non-hybridized and hybridized populations of two separate species of Gambusia (G. affinis and G. holbrooki). In order to examine if organisms from a population that had been previously exposed to hybridization would choose mates so as to not produce species hybrid offspring, 29 trials consisting of 9 different mate preference combinations and 87 individuals were recorded and analyzed. Once mate preference was determined for each female used in each trial, the effect that reproductive isolation had on reinforcement in hybrid zones was analyzed. The results …

Divergent Rnai Biology In Mites And Development Of Pest Control Strategies, Md Mosharrof Hossain Mondal

Dissertations

RNA interference (RNAi) has transformed genetics research by revolutionizing reverse genetics in the nearly three decades that have passed since its discovery. ~19-31 nt small non-coding RNAs play a central role in RNAi biology, and are found in all multicellular eukaryotes. In these animals, three major classes of small RNAs have been described: microRNA (miRNA), small interfering RNA (siRNA), and Piwi interacting RNA (piRNA), which are produced in distinct yet occasionally overlapping pathways. While miRNAs are involved in tuning endogenous gene expression, piRNAs and siRNAs are essential for defense against viruses and transposons. Argonaute proteins are the main effectors in …

The Influence Of The Educational Environment On College Student Activity Behaviors, Helen M. Ziegler

Dissertations

Healthy Campus 2020, an initiative that provides a framework to support campuses in improving the health of their students, staff, and faculty, recognizes physical activity as one of the top eleven priorities for positively influencing health risk behaviors in college populations (American College Health Association, 2012). However, there is not much research to support the best way to influence physical activity behaviors and what types of programs and facilities can provide the greatest impact. The purpose of this study was to investigate which components or programs within the higher education environment have the greatest influence on college students’ intention to …

The Effect Of An Historical Geology Course On Students’ Attitudes Towards Science And Their Knowledge Of Deep Time As A Threshold To Their Knowledge Of Evolution, Allan Nolan

Dissertations

In America there exists a conflict between a small group of its citizens and the concept of evolution. Researchers have studied this conflict and the ways in which teachers might approach educational methodologies that not only address evolution in a sensitive manner, but also remain legally acceptable.

This research was designed to address teaching evolution in the context of deep time – the concept that time is vast and that geology and biology operate in a timescale of hundreds of millions to billions of years. In previous peer-reviewed works, it has been stated that deep time acts as a threshold …

Coastal Wetland Dynamics Under Sea-Level Rise And Wetland Restoration In The Northern Gulf Of Mexico Using Bayesian Multilevel Models And A Web Tool, Tyler Hardy

Master's Theses

There is currently a lack of modeling framework to predict how relative sea-level rise (SLR), combined with restoration activities, affects landscapes of coastal wetlands with uncertainties accounted for at the entire northern Gulf of Mexico (NGOM). I developed such a modeling framework – Bayesian multi-level models to study the spatial pattern of wetland loss in the NGOM, driven by relative RSLR, vegetation productivity, tidal range, coastal slope, and wave height – all interacting with river-borne sediment availability, indicated by hydrological regimes. These interactions have not been comprehensively investigated before. I further modified this model to assess the efficacy of restoration …

Spatial Distribution And Stock-Recruitment Analysis Of The Atlantic Surfclam, Spisula Solidissima, In The Mid-Atlantic Bight And On Georges Bank, Jeremy Timbs

Master's Theses

Atlantic surfclams, Spisula solidissima, are long-lived bivalve molluscs with dispersive larval stages. Surfclam patchiness throughout the U.S. Exclusive Economic Zone (EEZ) has declined from the 1980’s to the present in all assessed regions (Delmarva, New Jersey, Long Island, Southern New England, and Georges Banks). Warming of Mid-Atlantic bottom waters is driving the surfclam stock into new habitat and extirpating the surfclams from nearshore areas. Based on a species distribution function model, the small surfclams appear to inhabit a greater area than the large market-size surfclams across the entire stock. The wider distribution of recent recruits relative to the fishable …

Creating Renewable Energy Through The Pairing Of Wastewater Remediation And Biofuel Production With Two Species Of Microalgae, Laura Brown

Master's Theses

In this study, two species of microalgae, Scenedesmus sp. isolated locally and Chlorella sorokiniana (UTEX 1230) were grown in municipal wastewater collected from Stennis Space Center, MS in order to assess whether or not the microalgae could remediate the wastewater into a clean and usable form while also producing the biomaterials necessary for fuel and other useful byproducts. Each species was cultured in 16 ˚C and 30 ˚C to assess functional variabilities at different times of the year. The microalgae’s ability to decrease nutrient concentrations in the wastewater and produce lipids and protein was assessed at three different growth stages: …

A Mechanistic Understanding Of Self-Propagating Amyloid-Β Oligomer Conformations In Alzheimer Disease, Dexter Nathanael Dean

Dissertations

Alzheimer disease (AD) is a fatal neurodegenerative disorder characterized by the widespread deposition of proteinaceous plaques abundant in amyloid-β (Aβ) aggregates. Although the plaques mainly contain high molecular weight, insoluble Aβ fibrils, the low molecular weight soluble aggregates called oligomers have been shown as the primary toxic species responsible for synaptic dysfunction and neuronal loss in AD. The process of aggregation is nucleation-dependent, but also highly stochastic and inhomogeneous resulting in biophysically diverse assemblies. Recent advances in the field indicate a potential correlation between the phenotypic diversity observed in AD subtypes and aggregate polymorphism. Therefore, understanding the molecular mechanisms which …

The Influence Of Conservation Tillage And Conventional Tillage On Soil Bacterial Diversity In Southern Illinois, Nasser Syed

Dissertations

Agriculture in the Midwest United States (Illinois, Indiana, Iowa, Michigan, Minnesota, Ohio, and Wisconsin) is a critically important component of the United States economy and also for world exports of food grain. This is well reflected in the 2012 Census of Agriculture which showed that these states had a market value of crop and livestock products sold in excess of $80,000,000,000 (USDA, 2012). Within the U.S. the three Midwest states, Illinois, Iowa, and Minnesota are ranked 2nd, 3rd, and 4th for the economic value of crops sold. This economic value of agriculture in the Midwest encompasses not only corn, soybeans, …

Personality In California Sea Lions (Zalophus Californianus) And Harbor Seals (Phoca Vitulina): Methodological Convergence And Species-Specific Emotional Repertoires, Amber De Vere

Dissertations

Despite the wide acceptance of animal personality as a valid area of study, research on marine mammal personality remains remarkably scarce. What literature does exist predominantly focuses on bottlenose dolphins (Frick, 2016; Highfill & Kuczaj, 2007; Kuczaj, Highfill & Byerly, 2012; Lilley, de Vere, Yeatre & Kuczaj, 2018; Moreno, Highfill & Kuczaj, 2017). There is also strong evidence for individual differences in grey seals (Robinson et al., 2015; Twiss & Franklin, 2010; Twiss, Culloch & Pomeroy, 2011; Twiss, Cairns, Culloch, Richards & Pomeroy, 2012), and preliminary research has provided evidence of broad personality factors in pinniped species using behavioral coding …

The Characterization Of The Transcription Factor Msab And Its Role In Staphylococcal Virulence, Justin Batte

Dissertations

Staphylococcus aureus is a common human pathogen that is responsible for a wide range of infections, ranging from relative minor skin infections to life-threatening disease such as bacteremia, septicemia, and endocarditis. S. aureus possesses many different virulent factors that aid in its ability to cause this wide array of infections. One major virulence factor includes the production of capsular polysaccharide (CP). The production of CP plays a major role in the virulence response during infection specifically by providing S. aureus an antiphagocytic mechanism that allows the pathogen to evade phagocytosis during an infection. S. aureus has developed complex genetic regulatory …

Root Dynamics Of Crop Plants In A High Carbon Dioxide World: Effects Of Elevated Versus Ambient Carbon Dioxide Levels And No-Till Versus Conventional Agricultural Management, Charlotte Barker

Dissertations

Due to the continuing increases is atmospheric carbon dioxide levels and its potential effect on food sources, there is an interest in evaluating the effect of elevated CO₂ concentration versus ambient CO₂ concentration in agricultural crop plants although more studies have focused on the aboveground portions of plants rather than the roots. Additionally, the conservation agricultural method, no-till, has been widely suggested as a possible method of increasing soil organic carbon and increasing soil moisture in a hotter world.

This research involves two major agricultural plants, Sorghum bicolor (sorghum), and Glycine max (soybean) grown under four conditions including …

Sibship Reconstruction For Inferring The Number Of Breeders Of Gulf Sturgeon In The Apalachicola River, Robbilyn Verges

Honors Theses

The Gulf sturgeon is an anadromous fish that inhabits the Gulf of Mexico and its neighboring river drainages. The species is currently listed as threatened due to habitat alterations and overfishing. In this study, we focused on the Apalachicola River in Florida, which has had several historic spawning locations of the sturgeon blocked by the Jim Woodruff Lock and Dam. Age-1 juvenile sturgeon from the year 2013 (n=31) and 2014 (n=131) were genotyped using fourteen microsatellite loci. Sibship reconstruction and parentage assignment was performed in order to determine the effective number of breeders (Nb) and the total number of spawning …

The Role And Contribution Of Saprotrophic Fungi During Standing Litter Decomposition Of Two Perennial Grass Species, Schizachyrium Scoparium And Schizachyrium Tenerum, Matthew Lodato

Master's Theses

In terrestrial ecosystems, most of the plant biomass produced enters the detrital pool, where microbial decomposers colonize, enzymatically degrade, and assimilate plant litter carbon and nutrients in amounts sufficient to bring about the decomposition of plant litter. Here, I estimated the biomass and production of fungi and microbial respiration associated with decaying Schizachyrium scoparium and Schizachyrium tenerum leaf litter, and constructed a partial organic matter budget estimating C flow into and through fungal decomposers. Significant losses in S. scoparium (57%) and S. tenerum (68%) leaf mass was observed during litter decomposition along with concomitant increases in fungal biomass, which reached …

Linkages Between Marsh Fragmentation, Prey Availability, And Blue Crab (Callinectes Sapidus) Abundance And Mortality, Lennah Shakeri

Master's Theses

Coastal marshes are important nursery habitats for many commercially important invertebrate species, yet these marshes are being lost worldwide at an unprecedented rate due to subsidence, erosion, climate change, and human activity. As marsh is lost, it creates the opportunity for submerged aquatic vegetation (SAV) colonization and establishment in newly created open water areas. Blue crabs, Callinectes sapidus, use both marsh edge and SAV habitat during the juvenile stages and support one of the largest fisheries in the Gulf of Mexico, worth over $70 million in 2015. This thesis studied the linkages between habitat type, SAV cover, benthic prey …

Life-History Characteristics And Fishery Dynamics Of Red Drum (Sciaenops Ocellatus), In The North-Central Gulf Of Mexico, Corbin Bennetts

Master's Theses

Red Drum (Sciaenops ocellatus) are highly targeted recreationally in the Gulf of Mexico, and support a small commercial fishery in Mississippi. Despite their popularity, the stock is assessed using data limited approaches that necessitate accurate life history information. I estimated the year-specific and year-aggregated escapement rates for the Mississippi stock (years 2004 to 2015), which were sensitive to mortality estimation methods; year-aggregated estimates were 6.9 to 28.2 % depending on the method, but temporal patterns were consistent. I then addressed concerns with previously estimated life-history characteristics by describing the sex-specific growth and reproductive dynamics. The three-parameter von Bertalanffy …

Vocalizations Of North American River Otters (Lontra Canadensis) In Two Human Care Populations, Sarah Walkley

Master's Theses

There is a dearth of information regarding the vocal repertoire of North American river otters (Lontra canadensis). This indicator species is cosmopolitan yet elusive, making recordings methodologically difficult in the wild. Therefore, this exploratory study uses video and audio recordings of two populations of North American river otters in human care to broaden the known vocal repertoire of river otters in various social contexts. The populations consist of a male-female pair at the Stamford Museum and Nature Center and a male-male pair at The Maritime Aquarium at Norwalk. This study is the first to examine the vocalizations produced …

Regional Variation In Migratory Behavior And Reproductive Output Of The Gulf Of Mexico Blue Crab Spawning Stock, Adam Kemberling

Master's Theses

The overarching goal of this research was to better understand the structure and boundaries of the blue crab stock(s) in the Gulf of Mexico, focusing on large-scale movements of spawning female crabs. Because spawning location is a primary determinant of larval transport pathways, understanding spawning locations and offshore movements of female blue crabs can inform stock identification and potentially clarify the somewhat conflicting population genetic information available for blue crabs. A large-scale mark-recapture study was conducted through the partnership of state/federal management agencies, the commercial fishing industry, recreational fisherman, tourists, and numerous academic institutions to shed light on the timing …

Detection, Activity Measurement And Phylogeny Of Ureolytic Bacteria Isolated From Elasmobranch Tissue, Yimu Yang

Master's Theses

Free-ranging marine elasmobranch tissue-associated micro-organisms were cultured from free-ranging Atlantic stingray (Dasyatis sabina) and Atlantic sharpnose sharks (Rhizoprionodon terraenovae). 16S rRNA gene phylogeny indicated bacteria community structure in both elasmobranchs were under phylum Proteobacteria, Firmicutes and Actinobacteria. By conducting split-plot ANOVA, we found the microbial richness is significantly different (P=0.0814) between two superorders of elasmobranch, which may largely due to their preferred habitats and feeding habits. Urease presentence and activity was detected in phylogenetically diverse bacterial strains. Species with high urea-hydrolyzing ability, such as Micrococcus luteus (shark blood isolate: 46.84 mU/mg protein; stingray blood isolate: 24.36 …

Spatial Variation In Basal Resources And Trophic Position Of Selected Fishes Of The North-Central Gulf Of Mexico, Christopher Fleming

Master's Theses

The North-central Gulf of Mexico is a complex hydrologic environment with freshwater influx that varies on spatial and temporal scales. Freshwater input exerts influence on the isotope values of organisms living in coastal ecosystems. The objectives of this study were to determine relationships between total length and isotope value, estimate basal resource usage and trophic position of target species from Mississippi Sound, reef, and pelagic environments, and identify differences and similarities in spatial patterns of collection. Muscle tissue samples were collected from October 2014 through September 2015. Stable isotope analysis identified a trophic gradient extending from nearshore to offshore, with …

Impact Of Prolonged Sitting On Central Hemodynamics: Role Of Intermittent Pneumatic Compression Therapy, Anna Kayleigh Downey

Master's Theses

Prolonged sitting (3-6 hours) negatively impacts peripheral vascular health. Whether sitting similarly impacts central cardiovascular hemodynamics and vascular stiffness is unknown. Purpose: Determine if prolonged sitting increases central blood pressure, aortic pulse wave reflection and vascular stiffness. Methods: In 10 subjects (Age=22±2 yrs, BMI=28±4kg/m², 3 females), brachial artery pulse wave analysis was performed before (baseline-BL), during, and after 3 hours of sitting. Aortic pulse wave velocity (PWV) was examined before and after sitting using carotid applanation tonometry coupled with oscillometry performed on left upper-thigh. For mechanistic insight, intermittent pneumatic compression (IPC) was applied during sitting (i.e., 3, 120 …

Factors Affecting The Regrowth Of Ilex Glabra In A Routinely Burned Longleaf Forest, Jaybus Price

Master's Theses

This study examines the effects of historical management by use of prescribed fire on Ilex glabra stems/m² and factors affecting the regrowth of I. glabra after a prescribed burn to gain beneficial knowledge for management purposes. Environmental factors and morphological parameters of I. glabra were sampled before and after a prescribed burn of the Longleaf Trace Nature Preserve in September 2016. The study site is located in Lamar County, Mississippi, just west of Hattiesburg, MS. Stem densities of I. glabra were collected once before the prescribed burn and twice after the prescribed burn at 2 month and 9 month …

Interplay Of Dgat1, Pdat1 And Dgat2 Enzymes In Plant Triacylglycerol Assembly, Anushobha Regmi

Master's Theses

Acyl-CoA:diacylglycerol acyltransferase (DGAT) catalyzes the transesterification of fatty acid from acyl-CoA to diacylglycerol (DAG) forming triacylglycerol (TAG, a.k.a oils and fats). Most plants have at least two unrelated DGAT genes, DGAT1 and DGAT2. Plants predominantly express only one during oil synthesis; the reason, however is not clear. A few studies have indicated that each enzyme prefers DAG and acyl-CoA substrates with different fatty acid compositions. Industrially desirable seed oil composition can be obtained through genetic engineering by replacing the endogenous enzyme with one that has different substrate selectivity. In Arabidopsis thaliana, DGAT1 and another unrelated enzyme PDAT1 are essential …

Lead, Copper, And Iron In University Tap Water, Alison Mclendon

Honors Theses

This study observed concentrations of lead, copper, and iron in university tap water over an eight-week span during and between the summer and fall semesters. First draw and 30s flush samples were taken after overnight stagnation from the Honor House, College Hall, J. B. George Building, and International Center bathrooms and analyzed with an inductively-coupled plasma mass spectrometer (ICPMS). There was no obvious correlation between time in the semester and metal concentrations. Relative iron levels rose and fell at the same time in all buildings, but there was little correlation between buildings for lead and copper concentrations. The Honor House …

Head Impact Biomechanics Of Collegiate Football Players, Samantha Eshleman

Honors Theses

This research study focused on the descriptive head impact biomechanics of collegiate American football players. The purpose of this study was to determine if there were statistical differences in the frequency, peak linear acceleration, and peak rotational acceleration between player position and impact location on the helmet during practice sessions. There were 31 players from the University of Southern Mississippi’s Division I football team that participated in the study. Participants were divided into four groups based on position: defensive skill, defensive line, offensive skill, and offensive line. The Head Impact Telemetry (HIT) System was incorporated with the Sideline Response System …

Effect Of American Football Helmet Chin Strap Placement On Measures Of Blunt Impact, Terrie Lane Jackson

Honors Theses

Approximately 1.8 to 3.6 million concussions occur annually across all sports.3 Although concussion is prevalent and is a growing concern, the mechanism behind this brain injury is still vaguely understood. The purpose of this research was to determine if chinstrap attachment location effects standard measures of helmet performance associated with concussion. To test this, three Schutt F7 American Football Helmets were impacted at the front, side, and rear locations under two conditions (high and low chinstrap attachment). Each helmet was fitted to an anthropometric test device outfitted with a 3-2-2-2 accelerometer and impacted by a steel impactor head affixed to …

Does Interest Equal Success? Evaluating Student Perceptions Of The Study Of Biology And Their Effects On Student Success In An Introductory Biology Course, Courtney Irene Barlow

Honors Theses

As instructors begin to devote more time to improving student perceptions of biology, the validity of these efforts should be determined. Do students possessing favorable views of biology regularly perform on a higher level than those with less favorable impressions, or would class time be better spent without exercises intended to increase student interest? The goal of this project was to address the research questions “How do students view the study of biology?”, “How do student perceptions of the subject area affect their performance in an Introductory Biology course?”, and “How does a student’s chosen area of study affect their …

Interactions Of Fire And Herbivory On The Management Of Ilex Glabra In Longleaf Pine Forests, Courtney R. Filliben

Honors Theses

The longleaf pine forest is characterized by the high levels of biodiversity and species richness that give it both ecological and economical importance. Decades of clear-cutting, habitat fragmentation, and natural fire restriction have reduced this once great forest system to a mere fraction of its original range. One of the specific causes of the decline of the longleaf pine is understory domination by woody shrubs. These shrubs limit the growth of characteristic grasses and forbs that are responsible for the majority of the biodiversity. The overall purpose of this study was to identify a new longleaf pine reforestation technique that …