Life Sciences Commons^™

The Expanding Marine Built Environment And Biofilm Formation Processes, Rachel Mugge

Dissertations

The marine built environment (i.e., places or things made or modified by humans) in the northern Gulf of Mexico is rapidly expanding and includes over 2,000 known historic shipwrecks, nearly 4,100 artificial reefs, and other built structures for natural resource extraction, marine aquaculture, renewable energy generation, munitions dumping areas, and commercial and recreational activities. While these structures have the potential to develop into artificial reefs, acting as biodiversity hotspots that provide food and shelter and facilitate organism transport, it is unclear how they affect biodiversity and ecosystem function in the marine environment. The success of artificial reefs to become ecosystems …

Analysis Of Ecological Tradeoffs Between Congeneric Shrimp In Coastal Mississippi Waters, Baylor K. Lynch

Honors Theses

Palaemonidae is an ecologically important and abundant family of shrimp that link the benthos to many estuarine food webs. Palaemon pugio and Palaemon vulgaris regularly co-occur along estuarine edge habitats despite previous studies suggesting different preferred sediment types and salinity regimes. The objective was to determine if competition is occurring between the congeners by comparing their relative abundance and assessing isotope niche space along an estuarine gradient. I seasonally sampled various edge habitats at four sites throughout Biloxi Bay, MS, using fyke nets fished over a tidal cycle from November 2020 to November 2021. Collected organisms were identified to the …

Relationships Between Vertical Ground Reaction Forces And Clubhead Velocity In Ncaa Division I Female Golfers, Jared Bush

Honors Theses

Golf biomechanics research has focused on clubhead velocity (CHV) for over a decade with the intent of discovering the physical attributes that contribute the most to CHV. Previous research has displayed the significant correlations of strength and power attributes to CHV, giving evidence for practitioners to integrate training to improve these attributes. Recent studies have referenced vertical ground reaction forces (vGRF) and how they affect CHV. In this study, vGRFs are tested for their correlations to CHV in NCAA Division I female golfers. Clubs of various lengths were used to determine correlations between each club and vGRFs. Correlations between CHV …

Plant Productivity And Diversity In Coastal Wetlands In Mississippi – Impact Of Hydrological Extremes, Kodi Feldpausch

Master's Theses

Wetlands are highly productive ecosystems that provide important ecosystem services and are threatened by extreme hydrological events. I evaluated how diversion of freshwater like Bonnet Carré Spillway openings in Louisiana, US, affected vegetation productivity and diversity in salt marshes on the neighboring Mississippi Gulf Coast, US. My study area is two estuarine systems that differ in their proximity to the Bonnet Carré Spillway, elevation, and salinity including Hancock County Marshes on the west, and Grand Bay National Estuarine Research Reserve (NERR) on the east in Mississippi. I collected above- and belowground biomass samples in 2020 and 2021, developed linear mixed-effects …

Hematophagy And Tick-Borne Rickettsial Pathogen Shape The Microbial Community Structure And Predicted Functions Within The Tick Vector, Amblyomma Maculatum., Abdulsalam Adegoke, Deepak Kumar, Khemraj Budachetri, Shahid Karim

Faculty Publications

Background: Ticks are the primary vectors of emerging and resurging pathogens of public health significance worldwide. Analyzing tick bacterial composition, diversity, and functionality across developmental stages and tissues is crucial for designing new strategies to control ticks and prevent tick-borne diseases.

Materials and methods: Here, we explored the microbial communities across the developmental timeline and in different tissues of the Gulf-Coast ticks (Amblyomma maculatum). Using a high-throughput sequencing approach, the influence of blood meal and Rickettsia parkeri, a spotted fever group rickettsiae infection in driving changes in microbiome composition, diversity, and functionality was determined.

Results: This study …

Rickettsia Parkeri Infection Modulates The Sialome And Ovariome Of The Gulf Coast Tick, Amblyomma Maculatum, Melina Garcia Guizzo, Khemraj Budachetri, Abdulsalam Adegoke, Jose M.C. Ribeiro, Shahid Karim

Faculty Publications

The Gulf Coast tick, Amblyomma maculatum, is a vector of several tick-borne pathogens, including Rickettsia parkeri. The ability of R. parkeri to persist within the tick population through transovarial and transstadial transmission, without apparently harming the ticks, contributes to the pathogen’s perpetuation in the tick population. Previous studies have shown that the R. parkeri load in A. maculatum is regulated by the tick tissues’ oxidant/antioxidant balance and the non-pathogenic tick microbiome. To obtain further insights into the interaction between tick and pathogen, we performed a bulk RNA-Seq for differential transcriptomic analysis of ovaries and salivary …

Trade-Offs Between Risks Of Predation And Starvation In Larvae Make The Shelf Break An Optimal Spawning Location For Atlantic Bluefin Tuna, Taylor A. Shropshire, Steven L. Morey, Eric P. Chassignet, Mandy Karnauskas, Victoria J. Coles, Estrella Malca, Raúl Laiz-Carrión, Øyvind Fiksen, Patricia Reglero, Akihiro Shiroza, José M. Quintanilla Hervas, Trika Gerard, John T. Lamkin, Michael R. Stukel

Faculty Publications

Atlantic bluefin tuna (ABT) (Thunnus thynnus) travel long distances to spawn in oligotrophic regions of the Gulf of Mexico (GoM) which suggests these regions offer some unique benefit to offspring survival. To better understand how larval survival varies within the GoM a spatially explicit, Lagrangian, individual-based model was developed that simulates dispersal and mortality of ABT early life stages within realistic predator and prey fields during the spawning periods from 1993 to 2012. The model estimates that starvation is the largest cumulative source of mortality associated with an early critical period. However, elevated predation on older larvae is …

Drift Macroalgal Distribution In Northern Gulf Of Mexico Seagrass Meadows, Kelly M. Correia, Scott B. Alford, Benjamin A. Belgrad, Kelly M. Darnell, M. Zachary Darnell, Bradley T. Furman, Margaret O. Hall, Christian T. Hayes, Charles W. Martin, Ashley M. Mcdonald, Delbert L. Smee

Faculty Publications

Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can increase the value of seagrass beds as habitat for nekton via added food resources and structural complexity. But, as algal biomass increases, it can also decrease light availability, inhibit faunal movements, smother benthic communities, and contribute to hypoxia, all of which can reduce nekton abundance. We quantified the abundance and distribution of drift macroalgae within seagrass meadows dominated by turtle grass Thalassia testudinum across the northern Gulf of Mexico and compared seagrass characteristics to macroalgal biomass and distribution. Drift macroalgae were most abundant in areas …

A Study Of Red Snapper (Lutjanus Campechanus) Ecology In The Northern Gulf Of Mexico And The Effect Of Variable River Outflow Using Stable Isotope Analysis Of The Food Web And Eye Lenses, Caitlin C. Slife

Dissertations

In the Mississippi Bight and surrounding waters, river outflow impacts the basal resources of the Red Snapper food web, altering carbon sources and impacting prey and predator isotopes. In this study, the impact of riverine outflow on nutrients, particulate organic matter (POM), and physical water parameters on Red Snapper and their food web was analyzed using stable isotope and stomach content analysis over 5 years. The Mississippi, Pearl, Pascagoula, and Mobile rivers were included in the analysis of river impact. The Mississippi and Mobile rivers were found to significantly impact nutrients and POM in the region. River outflow was also …

A Genomic Investigation Of Divergence Between Tuna Species, Pavel V. Dimens

Dissertations

Effective management and conservation of marine pelagic fishes is heavily dependent on a robust understanding of their population structure, their evolutionary history, and the delineation of appropriate management units. The Yellowfin tuna (Thunnus albacares) and the Blackfin tuna (Thunnus atlanticus) are two exploited epipelagic marine species with overlapping ranges in the tropical and sub-tropical Atlantic Ocean. This work analyzed genome-wide genetic variation of both species in the Atlantic basin to investigate the occurrence of population subdivision and adaptive variation. A de novo assembly of the Blackfin tuna genome was generated using Illumina paired-end sequencing data and …

Sorption Of Cellulases In Biofilm Enhances Cellulose Degradation By Bacillus Subtilis, Yijie Deng, Shiao Y. Wang

Faculty Publications

Biofilm commonly forms on the surfaces of cellulosic biomass but its roles in cellulose degradation remain largely unexplored. We used Bacillus subtilis to study possible mechanisms and the contributions of two major biofilm components, extracellular polysaccharides (EPS) and TasA protein, to submerged biofilm formation on cellulose and its degradation. We found that biofilm produced by B. subtilis is able to absorb exogenous cellulase added to the culture medium and also retain self-produced cellulase within the biofilm matrix. The bacteria that produced more biofilm degraded more cellulose compared to strains that produced less biofilm. Knockout strains that lacked both EPS and …

Systematic Overexpression Of Genes Encoded By Mycobacteriophage Waterfoul Reveals Novel Inhibitors Of Mycobacterial Growth, Danielle Heller, Isabel Amaya, Aleem Mohamed, Ilzat Ali, Dmitri Mavrodi, Padraig Deighan, Viknesh Sivanathan

Faculty Publications

Bacteriophages represent an enormous reservoir of novel genes, many of which are unrelated to existing entries in public databases and cannot be assigned a predicted function. Characterization of these genes can provide important insights into the intricacies of phage–host interactions and may offer new strategies to manipulate bacterial growth and behavior. Overexpression is a useful tool in the study of gene-mediated effects, and we describe here the construction of a plasmid-based overexpression library of a complete set of genes for Waterfoul, a mycobacteriophage closely related to those infecting clinically important strains of Mycobacterium tuberculosis and/or Mycobacterium abscessus. The arrayed …

Investigation Of Dead Ocean Quahogs (Arctica Islandica) Shells On The Mid-Atlantic Bight Continental Shelf, Alyssa Leclaire

Master's Theses

Ocean quahogs, Arctica islandica, are a long-lived, widely dispersed, biomass dominate in the Mid-Atlantic; therefore, quahog shells are valuable resources for studying climate change over time. Recently, dead ocean quahog shells were discovered south and inshore of the present biogeographic range of this animal. The presence of ocean quahog shells outside the current range is presumably a consequence of past regressions and transgressions of the Cold Pool, the bottom-trapped, cool body of water that allows boreal animals to live at lower latitudes. Dead ocean quahog shells were collected offshore of the DelMarVa Peninsula then radiocarbon-dated, evaluated for taphonomic condition, …

Effects Of Shoreline Development And Freshwater Discharge On Nekton Assemblage And Trophic Structure In A Northern Gulf Of Mexico Estuary, Glenn Schumacher

Master's Theses

Coastal salt marshes support a diversity of nekton and facilitate critical ecosystem functions but are threatened by shoreline development and climate change. Therefore, coastal ecosystem managers have begun incentivizing the use of living shorelines (LS), erosion control structures incorporating native plantings, to mitigate ecological consequences of marsh loss. However, post-restoration climate changes may shift habitat templates and negate positive effects of ecosystem restoration. I evaluated the ecology nekton along LS, natural marshes, hardened shorelines and greyed shorelines within Biloxi Bay, Mississippi, during a high freshwater discharge (HFD) period by comparing nekton assemblage (using species richness, Shannon-Wiener diversity, and relative abundance), …

Population Genetics Of Cownose Rays, Rhinoptera Spp. In The Western Atlantic, Helen Weber

Master's Theses

Using molecular tools (e.g., the NADH subunit II mitochondrial gene), this study was the first to document the Brazilian cownose ray, Rhinoptera brasiliensis, within the northwestern Atlantic (NWA), and was the first study to examine population structure in R. brasiliensis within the NWA or northern Gulf of Mexico (GMX), revealing novel insights into the population biology of the animal and extending its range by nearly 1,500 km. This study also examined the sympatrically occurring American cownose ray, R. bonasus, and found population structure between the NWA and the GMX and the NWA and the southwestern Atlantic (SWA). High …

Changes In The Morphology Of Widgeon Grass (Ruppia Maritima) With The Onset Of Reproduction And Impacts On Fish Assemblages At The Chandeleur Islands, La, Matthew Byrnes

Master's Theses

Seagrasses are important submerged coastal habitats that support nearshore communities. Ruppia maritima (widgeon grass) is a widespread species whose leaves branch extensively when reproductive. The goal of this study was to understand use of reproductive and non-reproductive R. maritima by fishes, recognizing the morphological change undergone by the plant when flowering. During the peak reproductive season in August and September 2021, R. maritima meadows at the Chandeleur Islands, LA were sampled to describe the spatial distribution and morphology of reproductive plants and investigate habitat use by fish assemblages. We assessed spatial trends in R. maritima presence and occurrence of reproduction …

Disturbance Ecology Of The Sonadora River Rock Pool Insect Assemblage At Luquillo Experimental Forest, Puerto Rico, Patrick Gilkey

Master's Theses

Freshwater rock pools can serve as habitat for aquatic insects. Flash-flooding can have profound effects on insect communities in streams and rivers, but these effects have not been studied on freshwater rock pools. The goal of this thesis was to describe ecological patterns of the Sonadora River rock pool insect community at the Luquillo Experiment Forrest, Puerto Rico, specifically in response to intense flash-flooding, and then perform experiments to elucidate possible processes to explain those patterns. The rock pools contained primarily three taxa of Dipteran (true-fly) larvae, in order of decreasing abundance, 1) a newly discovered species of ceratopogonid (biting …

Robust Network Stability Of Mosquitoes And Human Pathogens Of Medical Importance, Donald A. Yee, Catherine Dean Bermond, Limarie J. Reyes-Torres, Nicole S. Fijman, Nicole A. Scavo, Joseph Nelsen, Susan H. Yee

Faculty Publications

Background: The exact number of mosquito species relevant to human health is unknown, posing challenges in understanding the scope and breadth of vector–pathogen relationships, and how resilient mosquito vector–pathogen networks are to targeted eradication of vectors.

Methods: We performed an extensive literature survey to determine the associations between mosquito species and their associated pathogens of human medical importance. For each vector–pathogen association, we then determined the strength of the associations (i.e., natural infection, lab infection, lab dissemination, lab transmission, known vector). A network analysis was used to identify relationships among all pathogens and vectors. Finally, we examined how …

Characterizing Endogenous Dicer Products To Unravel Novel Rnai Biogenesis Pathways, Jacob Oche Peter

Dissertations

ABSTRACT

RNA interference (RNAi) is a pervasive gene regulatory mechanism in eukaryotes based on the action of multiple classes of small RNA (sRNA). Exploiting RNAi pathways in non-model systems have great potential for creating potent RNAi technologies. Here, we accessed RNAi-mediated control of gene expression in the two-spotted spider mite, Tetranychus urticae (T. urticae) using engineered dsRNA designed to modulate the host RNAi pathway and increase RNAi efficacy. Analysis of Dicer (Dcr) generated fragments revealed how exogenous RNAs access the host RNAi pathway in this animal, opening avenues for designing RNAi technology for their control. Further, some organisms …

Delineating The Role Of The Msaabcr Operon In Staphylococcal Overflow Metabolism, Gc Bibek, Gyan S. Sahukhal, Mohamed O. Elasri

Faculty Publications

Staphylococcus aureus is an important human pathogen that can infect almost every organ system, resulting in a high incidence of morbidity and mortality. The msaABCR operon is an important regulator of several staphylococcal phenotypes, including biofilm development, cell wall crosslinking, antibiotic resistance, oxidative stress, and acute and chronic implant-associated osteomyelitis. Our previous study showed that, by modulating murein hydrolase activity, the msaABCR operon negatively regulates the proteases that govern cell death. Here, we report further elucidation of the mechanism of cell death, which is regulated by the msaABCR operon at the molecular level in the USA300 LAC strain. We showed …

Expression And Purification Of The Bacterial Protein Curli Csga And Its Cross-Interactions With Amyloid-B, Leah Grace Cantrell

Honors Theses

One of the main causes of neurodegenerative diseases is aggregation of amyloid proteins that are toxic to the neurons. Proteins like amyloid-β (Aβ) and α-syneuclein (α-syn) form hallmark aggregate lesions that contribute to pathological processes in the brain in Alzheimer and Parkinson’s patients, respectively. Recent ground-breaking studies have suggested a link between the microbiota of the gut and neurodegenerative diseases, called the “gut-brain axis.” It has been long known that the protein, CsgA found in many enteric bacteria, forms amyloid fibers of its own called Curli. Curli fibrils are a structural component of bacterial colonies and maintain the integrity of …

Comparing The Reproductive Fitness Of Fundulus Hybrids And Their Parental Species (Fundulus Olivaceus And Fundulus Notatus) Within Mississippi Freshwater Contact Zones, Sarah Stovall

Honors Theses

Hybridization of closely related taxonomic groups within the Animal Kingdom has led to complex species interactions that are not well understood. Pre-zygotic or post-zygotic barriers complicate hybridization as a means to diversify; however, diverging hybrids may speciate and expedite evolution of involved taxa. This study pursues understanding of these intricate interactions using topminnow Fundulus notatus, Fundulus olivaceus, and their hybrids from the Fundulus notatus species complex. Persisting hybrids within riverine contact zones were hypothesized to experience barriers of hybrid breakdown from lower fitness in comparison to the pure species. Specimens were collected within four contact zones: Spring River, …

Reproductive Timing In Percina Aurora And Other Percina Species In The Pascagoula River Watershed, Malia Davidson

Honors Theses

The Southeastern United States is home to high levels of aquatic biodiversity and was recently named one of the Earth’s biodiversity hotspots. Within this region, growing human populations continue to place pressure on aquatic ecosystems and the resident species. Darters (Percidae: Percina) represent a large proportion of the freshwater fish diversity in the region. However, for some species the fundamentals of age, growth, reproductive timing and effort, and ecology remain poorly understood. That said, understanding the timing, duration, and effort allocated to reproduction is vital to successful management of any species. The pearl darter, Percina aurora, has been …

Oligomerization Of Amyloid-Β Peptide In The Presence Of Gangliosides–Implications For Alzheimer Disease, Sydney Boyd

Honors Theses

Alzheimer disease (AD) is a neurodegenerative disorder that leads to memory impairment and cognitive dysfunction in elderly populations worldwide. A key characteristic of AD is the formation of neuritic plaques composed of extracellularly deposited aggregates of amyloid-β (Aβ), an intrinsically disordered protein. Although Aβ fibrils were once thought to be the prime initiators of the disease, research has since been shifted to consider soluble, low molecular weight Aβ oligomers as the driving force behind AD toxicity. Due to its origin as a cleavage product of amyloid precursor protein (APP), an integral membrane protein, Aβ is known to perpetually interact with …

Invasion Properties Of Listeria Monocytogenes In Aged Cells, Mina Lane Chasteen Burton

Honors Theses

Listeriosis is a bacterial infection caused by the gram-positive pathogen Listeria monocytogenes. When compared to other foodborne illnesses, listeriosis has a higher death rate due to an increased incidence of complications such as meningitis, hydrocephalus, and sepsis in immunocompromised populations. Elderly individuals experience a condition known as immunosenescence, which is a gradual compromisation of the immune system brought on by natural aging. Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disorder causing premature aging, which allows HGPS cell lines to be used as models to further research in the field of biogerontology. This study utilizes the F2365 strain of …

The Reproductive Biology Of Small Fishes And The Clutch Concept: Combining Macroscopic And Histological Approaches, David C. Heins, Nancy J. Brown-Peterson

Faculty Publications

Accurate estimates of reproductive parameters important in understanding life history evolution and conservation of small fishes are dependent upon careful assignment of ovarian phases. Proper assignment is based upon the stages of propagule (oocyte) development, oocyte maturation and the location of any clutch or portion thereof within the ovaries. Macroscopic inspection and assignment of ovarian developmental phases have often been used for small freshwater fishes. By contrast, histological methods for assignment of reproductive phases have been developed and are widely used for marine fishes, but they have rarely been used for small freshwater fishes. We review oocyte development, ovum maturation, …

An Investigation On The Impact Of Intestinal Oxygen Availability On Survival And Regulation Of Virulence In Listeria Monocytogenes, Damayanti Chakravarty

Dissertations

The deadly foodborne pathogen Listeria monocytogenes is a gram positive facultative anaerobic bacterium. It is the third leading cause of death from food-borne illnesses. Once ingested, it encounters various stressors in the gastrointestinal (GI) tract, including acidic pH, bile, and alterations in oxygen availability. Various studies have been done regarding the pathogen’s survival mechanism against acid and bile. Since the lower parts of the GI tract are anaerobic, it is imperative to investigate how physiologically relevant anaerobic conditions impact L. monocytogenes’s survival. Transcriptomic analysis of L. monocytogenes under conditions mimicking the GI tract was performed. A large number of genes …

Investigation Of Dna Variability And Phylogenetic Relationships Of Perlesta (Plecoptera: Perlidae) In Mississippi, James C. Valentine, Mac H. Alford

Master's Theses

The genus Perlesta Banks, 1906 (Plecoptera: Perlidae) consists of 35 species, 33 native to the United States and Canada and two native to China. For over a century these small, brown stonefly adults and freckled yellow nymphs have gone by the name of the type species of the genus, Perlesta placida, but taxonomic work in the genus since 1989 has resulted in the recognition of additional species. These species were mostly recognized and described using morphological characteristics, but two areas that are lacking include (1) linking nymphs to adults and (2) phylogenetic analysis of all species occurring in Mississippi …

Induced Spawning Of Captive Tripletail Lobotes Surinamensis, Nicholas Adams

Master's Theses

The Tripletail, Lobotes surinamensis, is an emerging candidate species for U.S. marine aquaculture. This work aimed to address two bottlenecks for hatchery production of the species by developing a hormonal induction protocol to obtain fertile spawns from captive brooders and a method for sex identification of candidate brooders.

Single pairs selected among a captive-held broodstock conditioned under a natural photothermal cycle were induced with one of five treatments (n = 5 or 6 replicates per treatment). Control (no hormone) and hCG (1,100 IU.kg^-1 for females, 550 IU.kg^-1 for males) pairs did not spawn. Pairs treated with GnRHa …

Reassessment Of Species Boundaries And Phylogenetic Relationships In The Desmodium Ciliare Complex (Fabaceae) Using Morphological And Dna Data, Joshua Wilkinson

Master's Theses

Desmodium (Beggar's ticks) is a generally weedy genus of approximately 280 species in the angiosperm family Fabaceae (Subfamily Papilionoideae, Tribe Desmodieae) characterized by indehiscent loments constricted into segments. Within the Southeastern U.S., the Desmodium ciliare group is one of two Desmodium species complexes that have been historically difficult, with much argument about the limits of species and the role of hybridization. There are three commonly recognized species within the D. ciliare group, D. ciliare (Muhl. ex Willd.) DC., Desmodium marilandicum (L.) DC., and D. obtusum (Muhl. ex Willd.) DC., with two supposed hybrids in addition to the …