Life Sciences Commons^™

Oxidative Stress In Avian Embyros, Toshi Tsunekage

Dissertations

Oxidative stress has been implicated in mediating trade-offs in the evolution of life histories. Oxidative stress results from an imbalance in the production of free radicals and an organism’s antioxidant defenses. Higher metabolic rates associated with more rapid growth and shorter development periods may increase oxidative stress and accumulated cellular damage in embryonic tissues. In my dissertation I explored oxidative stress and antioxidant defenses in avian embryos. I measured levels of oxidative stress in tissues of different stage embryos of Japanese quail (Coturnix japonica), and tested if patterns of lipid peroxidation could be explained by changes in the developing embryo’s …

Macrobenthic Communities In The Northern Gulf Of Mexico Hypoxic Zone: Testing The Pearson-Rosenberg Model, Shivakumar Shivarudrappa

Dissertations

The Pearson and Rosenberg (P-R) conceptual model of macrobenthic succession was used to assess the impact of hypoxia (dissolved oxygen [DO] ≤ 2 mg/L) on the macrobenthic community on the continental shelf of northern Gulf of Mexico for the first time. The model uses a stress-response relationship between environmental parameters and the macrobenthic community to determine the ecological condition of the benthic habitat. The ecological significance of dissolved oxygen in a benthic habitat is well understood. In addition, the annual recurrence of bottom-water hypoxia on the Louisiana/Texas shelf during summer months is well documented.

The P-R model illustrates the decreasing …

Hospital Practices Related To Breastfeeding In Mississippi: A Socio-Ecological Approach, Amir Alakaam

Dissertations

Mississippi continues to have one of the lowest rates and the weakest support in respect to breastfeeding in the nation (Centers for Disease Control and Prevention, 2014a). Hospital practices supporting breastfeeding such as the Ten Steps to Successful Breastfeeding (TSSB) can dramatically increase breastfeeding rates and duration (Rosenberg, Stull, Adler, Kasehagen, & Crivelli-Kovach, 2008). The aim of this study was to explore breastfeeding practices in Mississippi hospitals based on two levels of the Socio-Ecological Model: the organizational level (phase I) examined the hospital practices based on the level of implementation of the TSSB; the individual level (phase II) examined knowledge …

Environmental Impacts And Carry-Over Effects In Complex Life Cycles: The Role Of Different Life History Stages, Nnaemeka F. Ezeakacha

Dissertations

A challenge faced by organisms with complex life cycles is how environmental factors experienced at an earlier life stage affect the fitness at that stage or are carried over to subsequent life stages. I used container-inhabiting mosquitoes: Aedes albopictus, Aedes aegypti, Aedes triseriatus and Culex quinquefasciatus to study the interactions and performance of life history stages under specific environmental factors. I investigated the effects of egg-desiccation tolerance on egg viability and larval performance in the Aedes mosquitoes. I found increase in egg hatch rate with relative humidity and interaction between relative humidity and egg storage period. Larval performance …

Investigating The Impact Of Reflexive Practices On College Students In A Science Laboratory Course, Chandrani Mishra

Dissertations

Emphasis on professional practices to develop students’ professionalism is currently a major focus of higher education. Studies have shown the benefits of reflexive practices in classroom to facilitate the development of students’ professional attitude or identity in some fields. Reflexive practices involve students in self-reflection where he/she reflects on his/her own actions. Little investigation about the benefits of reflexive practices in the development of students’ scientific identity in a science class led to my investigation. Development of a scientific identity of students and their overall interest and motivation in science is deemed essential for retaining students in STEM fields.

My …

Ecological Strategies And Disturbance Response Of Tropical Forest Trees: Insight From Functional Trait Variation, Oyomoare Lolade Osazuwa-Peters

Dissertations

Tropical forests store  40% of terrestrial carbon, process six times as much carbon as is released through fossil fuel use, and are epicenters of biodiversity. Despite all that we know about tropical forests, there remains much to discover about variation in ecological strategies, differences in the way species acquire limited resources through dissimilarities in construction and allocation patterns. We also know little as to how this variation shapes the resilience of tropical tree communities to disturbance. These forests are increasingly threatened by global change stressors, such as anthropogenic land-use and climate change. Recent advances in ecological literature show that …

Relationships Of Haemosporidian Parasites To Populations Of Their Avian Hosts In Eastern North America, Vincenzo Alexander Ellis

Dissertations

Avian Haemosporida are common, vector-transmitted blood parasites of birds throughout the world. During my dissertation research, I explored how multiple host species respond immunologically to natural infections in the wild (Chapter 1) and to experimental infections in the laboratory (Chapter 2). Despite their tractability as a model host-parasite system and a burgeoning literature on avian Haemosporida, little is known about how their populations interact across large areas (hereafter “regions”). I present data from parasite surveys of birds across eastern North America suggesting that continental parasite populations track host populations across the region, but also that the host breadth of a …

Determining How Stable Network Oscillations Arise From Neuronal And Synaptic Mechanisms, Diana Martinez

Dissertations

Many animal behaviors involve the generation of rhythmic patterns and movements. These rhythmic patterns are commonly mediated by neural networks that produce an oscillatory activity pattern, where different neurons maintain a relative phase relationship. This thesis examines the relationships between the cellular and synaptic properties that give rise to stable activity in the form of phase maintenance, across different frequencies in a well-suited model system, the pyloric network of the crab Cancer borealis. The pyloric network has endogenously oscillating ‘pacemaker’ neurons that inhibit ‘follower’ neurons, which in turn feed back onto the pacemaker neurons. The focus of this thesis …

Attraction And Risk In Urban Bird Habitats, Megan E. Litwhiler

Dissertations

Urban expansion is an increasing threat to native bird populations. Consequently, maintaining and developing safe urban habitat space is necessary for conservation. Birds living in, or migrating through, urban areas utilize a variety of managed green-spaces such as parks, gardens, college campuses, and cemeteries. In addition to managed habitats, birds may use abandoned property that has been reclaimed by vegetation and associated spontaneous, biological communities. Such urban habitats may provide valuable resources for birds and other wildlife; however, these sites often contain high densities of non-native plants and can be polluted, potentially imparting a greater risk than benefit to the …

The Role Of Arabidopsis Aminoalcoholphosphotransferase 1 And 2 In Plant Development And Oil Production And Transcriptional Regulation Of Seed Oil Accumulation By Glabra2, Yu Liu

Dissertations

Vegetable oils are important commodities as human foods, animal feeds, renewable industrial feedstocks, and biofuels. Many biochemical and regulation events are involved in seed oil formation, including phospholipids metabolism and transcriptional regulation. In this work, I investigated 1) the role of aminoalcoholphosphotransferases (AAPTs) in phospholipid synthesis and plant development, 2) the effects of AAPTs on seed storage lipid production in Arabidopsis and the emerging oil crop Camelina, and 3) the interaction of the lipid mediator phosphatidic acid (PA) with GLABRA2 (GL2), a negative regulator in seed oil production. AAPTs are the enzymes that produce phosphatidylcholine (PC) and phosphatidylethanolamine (PE). The …

Investigations Of Filarial Nematode Motility, Response To Drug Treatment, And Pathology, Charles Nutting

Dissertations

More than a billion people live at risk of chronic diseases caused by parasitic filarial nematodes. These diseases: lymphatic filariasis, onchocerciasis, and loaisis cause significant morbidity, degrading the health, quality of life, and economic productivity of those who suffer from them. Though treatable, there is no cure to rid those infected of adult parasites. The parasites can modulate the immune system and live for 10-15 years. Testing of compounds against filarial nematodes is complicated due to a lack of an objective platform on which to analyze in vitro treatments. There is no published, immunocompetent laboratory model for lymphatic filariasis. This …

Regulation Of Vancomycin Resistance And Stress Response By The Msaabcr Operon In Staphylococcus Aureus, Dhritiman Samanta

Dissertations

Staphylococcus aureus is the predominant cause of public health problems around the world. Vancomycin has been an important antibiotic against Methicillin Resistant Staphylococcus aureus (MRSA) infections. However, Vancomycin Intermediate S. aureus (VISA) strains have been reported. These strains are characterized by thick cell walls, reduced autolytic rate, reduced PBP4 activity, and increased amount of D-Ala-D-Ala termini in the cell wall. In this study, we show that the msaABCR operon regulates vancomycin resistance in two clinical VISA strains. Deletion of the msaABCR operon in strains Mu50 and HIP6297 resulted in a significant decrease in the minimum inhibitory concentration (MIC) for vancomycin. …

Assessing Biogeochemical Impacts And Environmental Conditions Associated With Cross-Shelf High Chlorophyll Plumes In The Northern Gulf Of Mexico, Erin Brooke Jones

Dissertations

The northern Gulf of Mexico is a complex marine system subject to episodic physical phenomena such as loop current eddies. Flow fields generated by these eddies can result in cross-shelf exchanges between riverine influenced shelf waters and the offshore water column. This study considers the impacts of high chlorophyll plumes (HCPs) resulting from cross-shelf exchanges to the bio-optical properties of affected waters and how these plumes are influenced by their environment. The seasonal, interannual and decadal chlorophyll cycles of the Gulf of Mexico and the northern Gulf of Mexico are described to provide context for evaluating the ecological effects of …

Regulation Of Glial Cell Line-Derived Neurotrophic Factor (Gdnf) Production In Voluntary And Involuntary Muscle, John-Mary Vianney

Dissertations

Glia cell line-derived neurotrophic factor (GDNF) is a survival factor for subpopulations of neurons, including somatic and autonomic motor neurons. These neurons depend, in part, on GDNF that is synthesized and secreted by their target tissues. It has been shown that a number of tissues in the periphery express GDNF and these target tissues differ in their composition, function, and in the case of different muscle cell types, their contractile characteristics. Whether the processes regulating GDNF production in these different tissues is similar or different is poorly understood. The broad goal of this study is to examine factors that normally …

Protein Domain Linker Prediction: A Direction For Detecting Protein – Protein Interactions, Maad Mohammad Hasan Shatnawi

Dissertations

Protein chains are generally long and consist of multiple domains. Domains are the basic of elements of protein structures that can exist, evolve and function independently. The accurate and reliable identification of protein domains and their interactions has very important impacts in several protein research areas. The accurate prediction of protein domains is a fundamental stage in both experimental and computational proteomics. The knowledge is an initial stage of protein tertiary structure prediction which can give insight into the way in which protein works. The knowledge of domains is also useful in classifying the proteins, understanding their structures, functions and …

Climate-Driven Change In Himalayan Rhododendron Phenology, Robert Evan Hart

Dissertations

Phenology – the seasonal timing of life-history events – is a critical dimension of natural history. It is also one of the earliest and most noticeable traits by which organisms respond to climate change. However, these responses are complex, and only beginning to be understood, especially in the montane and alpine environments that are among the ecosystems most vulnerable to climate change. Drawing from diverse data sets and employing multiple methodologies, I examined how climate affects phenology in Himalayan Rhododendron spp. Comprehensively monitoring flowering phenology over gradients of season and elevation on Mt. Yulong, China – home to a diverse …

Spatial Ecology, Genetic Diversity And Population Structure Of Armenian Vipers, Montivipera Raddei, In Two Different Landscapes, Jeffery Alan Ettling

Dissertations

In an effort to gain a better understanding of the impact that human-modified landscapes are having on snake populations I studied the spatial ecology, gene diversity and population structure of the Armenian Viper, Montivipera raddei in two different landscapes in Armenia. We first examined the spatial ecology and habitat use of Armenian Vipers in a human-modified landscape with a combination of agricultural fields and overgrazed native steppe habitat. While there were no differences in movement rates for either sex through croplands compared to steppe, we did find that males had larger home ranges during the spring if it included cropland. …

Development And Functioning Of Mycorrhizal Root Systems Under Non-Uniform Rootzone Salinity, Asha Christopher

Dissertations

Arbuscular mycorrhiza are obligate symbionts that live in association with most plant roots. The fungal mycelium extracts nutritional elements from the soil, and supplies these to plants in exchange for plant photoassimilates. The present study investigated the effects of root colonization by arbuscular mycorrhizal fungi on growth and nutrient uptake of tomato (Solanum lycopersicum L.) and Sudan grass (Sorghum bicolor L.) exposed to topsoil salinity through a horizontal split-root set-up. Roots in the upper compartment were exposed to substrate salinity, while lower compartment roots had access to non-saline nutrient solution. Despite roots being well-colonized by mycorrhizal fungi, there was no …

Failing To Replicate: Hypothesis Testing As A Crucial Key To Make Direct Replications More Credible And Predictable, Pedro Fernando Mateu Bullón

Dissertations

Theory cannot be fully validated unless the original results have been replicated, resulting in conclusion consistency. Replications are the strongest source to verify research findings and knowledge claims. Sciences such as medicine, chemistry, physics, genetics, and biology, are considered successful because their knowledge claims are buttressed by a large set of replications of original studies. Unfortunately in the social sciences many attempts to replicate fail and thus there is a continuing need for replication studies to confirm facts, expand knowledge to gain new understanding, and verify hypotheses. Two plausible explanations for the failure to replicate in the social sciences could …

Innovative Governance And Natural Resource Management In Kenya: Procedural And Substantive Outcomes Of Civil Society Participation, Jane Omudho Okwako

Dissertations

Kenya’s environmental sector is embracing co-management to address major threats to wildlife. In the past two decades, the Municipal-Community-Private Sector Partnership (MCPP) model evolved to address the threats. This dissertation seeks to explain variations in partnership outcomes. It evaluates whether the model as introduced empowers communities to be conservation stewards.

This study hypothesized the impact of five variables. These are decentralization of power, elite support, capacity of community organizations, partnership formalization, and resources expended. The findings confirm that three variables are indispensable and two minimally influence empowerment. More decentralized management structures are enabling and supportive of empowerment. However, empowerment is …

Novel Bioinformatic Approaches For Analyzing Next-Generation Sequencing Data, Yan Peng

Dissertations

In general, DNA reconstruction is deemed as the key of molecular biology since it makes people realize how genotype affects phenotypes. The DNA sequencing technology emerged exactly towards this and has greatly promoted molecular biology’s development. The traditional method, "Sanger," is effective but extremely expensive on a cost-per-base basis. This shortcoming of Sanger method leads to the rapid development of next-generation sequencing technologies. The NGS technologies are widely used by virtue of their low-cost, high-throughput, and fast nature. However, they still face major drawbacks such as huge amounts of data as well as relatively short read length compared with traditional …

Spatial, Temporal And Demographical Analysis Of Gulf Of Mexico Research Priorities, The Effect Of The Deepwater Horizon Oil Spill, Stephen Hiller Sempier

Dissertations

A set of twenty equally-weighted national ocean research priorities were define in 2007, but it was not clear if these priorities applied for the Gulf of Mexico. A series of three longitudinal surveys of people who conduct research, sponsor research or use research for professional or recreational purposes was released that focused on the twenty research priorities and asked people how they rated each. A convenience sampling method was employed, which suggests that the results are constrained to the survey respondents and should not be extrapolated to a larger population. More than 1,500 people completed the 2013 GMRP survey and …

Species Delimitation, Phylogenetics, And Biogeography Of The Catfish Genus Rhamdia Bleeker (Heptapteridae) Of Central America And The Trans-Andean Region Of Colombia, Carmen Liliana Hernández Torres

Dissertations

A recent taxonomic revision of the Neotropical catfish genus Rhamdia (Pisces: Siluriformes: Heptapteridae) reduced a number of described species to synonymy, especially under a broadly circumscribed R. quelen. Evidence is presented here from DNA sequence data, external and internal morphology, and morphometrics that argues for the recognition of R. guatemalensis in Central and northern South America and R. saijaensis and R. cinerascens in the Pacific drainages of Colombia and Ecuador, respectively. The DNA data indicate that all trans-Andean samples form a monophyletic group, within which there are separate clades corresponding to R. laticauda and the synonymized R. guatemalensis, …

Phylogenetic Relationships Of Samydaceae And Taxonomic Revision Of The Species Of Casearia In South-Central Asia, Tharangamala Samarakoon

Dissertations

The flowering plant family Samydaceae was recently reinstated to include 14 genera and about 256 species of tropical trees and shrubs. Preliminary analyses of relationships in the family, however, indicated that the largest genus in the family, Casearia, is not monophyletic and that several smaller groups are probably misplaced. In order to affirm or refute those hypotheses, additional DNA sequence data with broader taxon sampling from the Old World were gathered for phylogenetic analysis. In particular, rapidly evolving plastid (matK, ndhF, psbA-trnH, trnL, and trnL-F) and nuclear (EMB2765 and GBSSI) DNA …

Novelty Or Knowledge? A Study Of Using A Student Response System In Non-Major Biology Courses At A Community College, Tasha Herrington Thames

Dissertations

The advancement in technology integration is laying the groundwork of a paradigm shift in the higher education system (Noonoo, 2011). The National Dropout Prevention Center (n.d.) [JS1] claims that technology offers some of the best opportunities for presenting instruction to engage students in meaningful education, addressing multiple intelligences, and adjusting to students’ various learning styles. The purpose of this study was to investigate if implementing clicker technology would have a statistically significant difference on student retention and student achievement, while controlling for learning styles, for students in non-major biology courses who were and were not subjected to the technology. This …

Biofilm Production By Food-Transmitted Bacteria And Their Control By Selected Nanoparticles, Mariam Al Shamsi

Dissertations

Biofilm is a population of bacteria attached to any types of surfaces and impeded in a self-produced matrix of extracellular polymeric substances. Biofilm exhibit up to 1000 fold antibiotic increased resistance to a broad range of antimicrobial agents. Several food-transmitted microorganisms are capable of forming biofilms and considered as a major source of contamination, transmission and infection. In the last few decades, nanoparticles has gained a great attention for their potential applications as antimicrobial agents. The aim of this work was to assess the biofilm formation capacity of food-transmitted bacteria under various environmental conditions and to investigate the efficacy of …

Comparative Phylogeography And Demographic Histories Of West Indian Birds, Maria Wilhelmina Barbosa De Oliveira Pil

Dissertations

My dissertation investigates the demographic history of multiple island populations of several Caribbean bird species through an assessment of contemporary genetic diversity, while inferring relationships between the comparative demography of individual island populations and characteristics of the islands and species. The sizes and distributions of populations vary over time, and episodes of expansion and contraction create characteristic patterns of genetic variation within and among populations. Consequently, contemporary patterns of genetic diversity open a window onto demographic and phylogeographic history. The strength of the study lies in the scale and comprehensiveness of the analysis, encompassing most of the West Indian islands …

Development Of A Therapeutic Model Of Early Liver Cancer Using Crocin-Coated Magnetite Nanoparticles, Rkia El-Kharrag

Dissertations

Hepatocellular carcinoma is one of the most common health problems that is difficult to treat. As a result of the side effects frequently experienced with conventional cancer treatments, there has been a growing interest to develop controlled drug delivery system that can reduce the mortality rate of liver cancer patients and un-harm healthy tissues. Magnetite nanoparticles are potentially important in hepatocellular carcinoma treatment, since they can be used as delivery system. Pure and coated magnetite nanoparticles were synthesized via modified co-precipitation method in air at low temperature. Various reaction parameters and coating materials have been investigated and characterized. Among these …

E Pluribus Unum: What Individual Whales Can Tell Us About Enigmatic Species Distribution And Social Organization, Tanya Marie Lubansky

Dissertations

Large whales have historically been difficult to study and many aspects of their ecology remain unknown especially at the long -term population level. The ability to identify individual whales based on natural markings provides the opportunity to track individuals over time and space; this data may offer more insight into the ecology of whales than previously imagined. This study demonstrates use of photo-identification data to model both social structure and habitat selection, minimizing the need for invasive research and greatly increasing the sample size used in such endeavors. A conditional logistic model is written for a 20-year sightings dataset on …

Galapagos Seabirds' Lice Community: Host Hetero-Specific Interactions And Parasite Evolution, Jose Luis Rivera

Dissertations

My dissertation focused on understanding the factors behind host-parasite specificity and parasite diversification, using Galapagos seabirds and their ectoparasites as the study system. This system comprised the seabird hosts (magnificent and great frigatebirds, Nazca, blue-footed and red-footed boobies) and nine species of ectoparasitic lice (one Pectinopygus ischnoceran louse species infecting each host, two species of Colpocephalum amblyceran lice, one on each frigatebird species, and two shared amblyceran lice, Eidmanniella albescens found on Nazca and blue-footed boobies and Fregatiella aurifasciata found on the two frigatebirds). Using as focal species Eidmanniella albescens and Fregatiella aurifasciata, which infect multiple hosts, I analyzed how …