Biology Commons^™

Activity-Regulated Micrornas: Modulators Of Synaptic Growth At The Drosophila Neuromuscular Junction, Katherine Ruth Nesler

Electronic Theses and Dissertations

It is well established that long-term changes in synaptic structure and function are mediated by rapid activity-dependent gene transcription and new protein synthesis. A growing body of evidence supports the involvement of the microRNA (miRNA) pathway in these processes. We have used the Drosophila neuromuscular junction (NMJ) as a model synapse to characterize activity-regulated miRNAs and their important mRNA targets. Here, we have identified five neuronal miRNAs (miRs-1, -8, -289, -314, and -958) that are significantly downregulated in response to neuronal activity. Furthermore we have discovered that neuronal misexpression of three of these miRNAs (miR-8, -289, and -958) is capable …

Rala And Rab8 Regulate Drosophila Embryogenesis, Zhongyuan Zuo

Electronic Theses and Dissertations

Pseudocleavage furrow dynamics initiate at cycle 10 to help with mitotic divisions that lack cytokinesis. Permanent furrows then form at the beginning of cellularization (cycle 14). Cytoskeletal networks such as F-actin and non-muscle Myosin II have been demonstrated to be required for furrow formation and provide anchor points for chromosomal segregation. However, what drives the onset of furrow formation and membrane addition remains largely unclear. In my thesis, I have explored RalA and Rab8 function during furrow formation at metaphase and cellularization stages. These furrows are critical for correct chromosomal segregation, while disruption of furrow formation results in severe developmental …

Post-Transcriptional Shaping Of Neurons: The Role Of Mirnas And Fmrp-Interacting P-Body Components In Regulating Neuronal Structure, Breanna Symmes

Electronic Theses and Dissertations

Changes in synaptic structure in response to neuronal stimulation are believed to underlie the processes of learning and long-term memory. However, the mechanisms for these structural modifications are poorly understood. It is well-known that activity-dependent synaptic modifications rely upon new protein synthesis, and rapid new protein synthesis, at that. Therefore, it is widely believed that pools of messenger RNAs held in a state of translational repression are transcribed in a neuronal cell body prior to stimulation, and transported to the synapse, where they reside until stimulation occurs.

This study investigates the roles and interactions of translational repression mechanisms to better …

Migratory Connectivity And Carry-Over Effects In Northwest Atlantic Loggerhead Turtles (Caretta Caretta, L.), Simona Ceriani

Electronic Theses and Dissertations

Migration is a widespread and complex phenomenon in nature that has fascinated humans for centuries. Connectivity among populations influences their demographics, genetic structure and response to environmental change. Here, I used the loggerhead turtle (Caretta caretta, L.) as a study organism to address questions related to migratory connectivity and carry-over effects using satellite telemetry, stable isotope analysis and GIS interpolation methods. Telemetry identified foraging areas previously overlooked for loggerheads nesting in Florida. Next, I validated and evaluated the efficacy of intrinsic markers as a complementary and low cost tool to assign loggerhead foraging regions in the Northwest Atlantic Ocean (NWA), …

Evaluation Of The Three-Dimensional Patterns And Ecological Impacts Of The Invasive Old World Climbing Fern (Lygodium Microphyllum), Alexis Maldonado

Electronic Theses and Dissertations

Invasion by non-native species has had significant ecological and economic impacts on a global scale. In the state of Florida, Old World climbing fern (Lygodium microphyllum) is an invasive plant listed by FLEPPC as a category one invader with significant ecological impacts that threaten native plant diversity. This species relies on existing vegetative structures for support to climb into the forest canopy and forms dense mats that cover tree crowns. This subsequently affects the resources available to other species present. Quantifying the structural changes due to the presence of this species has proved logistically difficult, especially on a large spatial …

Regulators Of Repo: A Search For Gcm/Repo Transcription Factors, Kathy Ann Nipper

Electronic Theses and Dissertations

The role of the Drosophila melanogaster gene glial cells missing (gcm) is that of a binary switch in both the central nervous system (CNS) and the peripheral nervous system (PNS) in specification of the glial fate for multipotent precursor cells. However, Gcm is also essential for maturation of hematocytes and tendon cells ( Alfonso and Jones, 2002; Jones, et al., 1995; Hosoya et al., 1995; Soustell et al., 2004). The varied outcomes of gcm expression imply the interaction of co-factors capable of giving the Gcm protein different "meanings" in different developmental contexts. The Gcm target repo is expressed exclusively in …

Effects Of Weaning Age On Body Composition And Growth Of Ex Situ California Sea Lion (Zalophus Californianus) Pups, Brandon Davis

Electronic Theses and Dissertations

Pinnipeds exhibit a wide range of lactation strategies that vary from just a few days to nearly three years in duration. Phocids have a relatively short, intense nursing period culminating with weaning after just a few days or weeks, while dependent otariids generally take several months of consuming a combined milk and solid food diet before being completely independent. The transition to nutritional independence can be particularly challenging for newly weaned pups, which must adjust to behavioral, physiological and nutritional changes as a milk diet is replaced with solid food. An interruption in energy resources during this formative stage could …

Using Land Cover Mapping And Landscape Metrics To Evaluate Effects Of Urban Development On Ecological Integrity In Florida, Michael Gilbrook

Electronic Theses and Dissertations

The widespread loss and degradation of habitat constitutes the largest threat to biodiversity in North America. While regulatory programs such as the Endangered Species Act of 1973 and wetland permitting under the Clean Water Act have addressed acute assaults on critical habitat, large areas of unprotected uplands have been lost. Urban development, particularly the advent of lower density suburban and rural sprawl, has greatly diminished the extent of contiguous patches of forest habitat and introduced a host of other undesirable effects on ecosystem function. This study sought to evaluate the extent of urban sprawl and its effects on ecological integrity …

Movements, Fishery Interactions, And Unusual Mortalities Of Bottlenose Dolphins, Steven Shippee

Electronic Theses and Dissertations

Bottlenose dolphins inhabiting coastlines and estuaries in Florida have been impacted in the past decade by development, algal blooms, catastrophic pollution, and fishery interactions (FI). Dolphins react to disturbance and environmental stressors by modifying their movements and habitat use, which may put them in jeopardy of conflict with humans. FI plays an increasing role in contributing to dolphin mortalities. I investigated dolphin movements, habitat use, residency patterns, and frequency of FI with sport fishing. Tagging studies with short-term data tags and bolt on radio-transmitters were done in several locations in Florida and the east coast providing fine-scale measurements of swimming, …

Physiological Constraints On Warm-Water Habitat Site Selection And Utilization By The Florida Manatee (Trichechus Manatus Latirostris) In East Central Florida, Ann Spellman

Electronic Theses and Dissertations

Living at the northern limits of its geographic range, the Florida manatee is particularly susceptible to cold stress-related mortality during the winter months, with most deaths occurring in the lower two-thirds of the state. Contributing to this cold stress susceptibility is the manatee's limited physiological and behavioral responses available when thermally stressed. While capable of migrating south in response to falling water temperatures, manatees must still find warm water when ambient river temperature drops below 20°C for more than a few days. This is in part due to the species low metabolic rate, limited capacity for thermogenesis, and limited ability …

Integral Projection Models Reveal Interactive Effects Of Biotic Factors And Disturbance On Plant Demography, Matthew Tye

Electronic Theses and Dissertations

Understanding factors limiting population growth is crucial to evaluating species persistence in changing environments. I used Integral Projection Models (IPMs) to elucidate the role of biotic interactions and disturbance on population growth rate in two plants: Helianthemum squamatum, a perennial endemic to gypsum habitats in central Spain, and Liatris ohlingerae, a long-lived perennial endemic to the Lake Wales Ridge of central Florida. In H. squamatum, there was a strong positive effect of trampling in the site with the highest plant density and moderate positive effects of seed addition in the site with the lowest plant density. Differences in treatment effectiveness …

Effects Of Mechanical Habitat Disturbance On The Diversity And Network Structure Of Plant-Bee Interaction Networks In Central Florida, Karlie Carman

Electronic Theses and Dissertations

Ecological interactions within a community shape the structure of ecosystems and influence ecosystem function. Plant-pollinator interactions exist as mutualistic exchange networks that may collapse as habitat loss occurs, thereby threatening the overall health of an ecosystem. Understanding the impacts of human-mediated habitat disturbance on ecological interactions is therefore crucial for conservation efforts. Archbold Biological Station (ABS) in Venus, Florida contains over 2000 hectares of protected Florida scrub habitat nested within a human-dominated environment that is threatened by anthropogenic habitat disturbance. In past studies, over 113 bee species and 157 associated host plants, many endemic to the Lake Wales Ridge, have …

Effects Of Biotic Interactions On Coastal Wetland Communities With Applications For Restoration, Melinda Donnelly

Electronic Theses and Dissertations

Coastal wetland plants serve as ecological engineers in a physiologically stressful environment and the loss of coastal wetlands can cause negative effects throughout the estuarine system. Due to increased degradation of coastal habitats worldwide, interest in restoration has increased around the world. An understanding of the biotic processes affecting species distribution and diversity is critical for future conservation, management, and restoration of coastal wetlands. The purpose of my study was to test the effects of biotic interactions on native coastal wetland plants and determine how these interactions may be incorporated into current and future restoration projects. I had three primary …

A Time-Course Analysis Of Behavioral Plasticity And Differential Gene Expression Patterns In Response To Density In Schistocerca Americana (Orthoptera: Acrididae), Steven Gotham

Electronic Theses and Dissertations

Phenotypic plasticity is the ability of the genotype to express alternative phenotypes in response to different environmental conditions and this is considered to be an adaptation in which a species can survive and persist in a rapidly changing environment. Some grasshoppers and locusts are capable of expressing an extreme form of density-dependent phenotypic plasticity, known as locust phase polyphenism. At low population density, the individuals typically have a cryptic coloration as nymphs, are less active, and only seek out conspecifics for reproductive purposes. At high density, however, they develop a drastically different phenotype in which they have a conspicuous coloration, …

The Effects Of Non-Native Species On Two Life-Stages Of The Eastern Oyster Crassostrea Virginica, Wei Yuan

Electronic Theses and Dissertations

Since their recent introductions into Florida waters, three nonnative species [Perna viridis Linnaeus, 1758 (Asian green mussel), Mytella charruana d'Orbigny, 1846 (charru mussel) and Megabalanus coccopoma Darwin, 1854 (pink titan acorn barnacle)] have expanded both north and south along the Atlantic coast. Very little research has been done to understand how these nonnative species interact with the native eastern oyster (Crassostrea virginica Gmelin, 1791), which is a keystone species that provides important ecological services and economic benefits. To test the potential effects of P. viridis, M. charruana and M. coccopoma on C. virginica, I addressed the following questions: 1a) Does …

Development Of In Vitro Chylomicron Assay Using Caco-2 Cells, Yuxi Sun

Electronic Theses and Dissertations

Dietary fats are mainly transported by the intestine in lipoproteins: chylomicrons (CMs) and very low density lipoproteins (VLDLs). Unfortunately, studies of the intestinal absorption of dietary fat have been hampered by the lack of an adequate in vitro model system. As an in vitro model Caco-2 cells are able to secrete lipoproteins. We investigated the possible factors that may affect the secretion of CMs through the ultracentrifugation technique. The dose-dependent effects of oleic acid, mono-olein, egg lecithin, collagen matrix, and the effect of cell differentiation on CM secretion were then tested. We found that oleic acid, lecithin, and cell differentiation …

Investigating Potential Bioactive Compounds From Rhodococcus And Their Effects On Mcf7 Breast Cancer Cells, Megan N. Crabtree

Electronic Theses and Dissertations

Many drugs used in the treatment of various cancers are derived from or influenced by compounds from nature. The soil bacterium Rhodococcus is of interest because of its identified secondary metabolic pathways and the production of novel natural antibiotics from several strains. In this study, a solid agar extraction method was used to collect compounds from strains of Rhodococcus. These bacterial compound extracts were then tested using a MTT assay in order to evaluate their effectiveness in augmenting MCF7 breast cancer cell death. The results of two way ANOVA analyses revealed 18 compound extracts from 15 strains of Rhodococcus that …

Vegetation Response After Invasive Tamarix Spp. Removal In The Riparian Zone And Semi-Arid Rangeland Ecosystems, Hisham Nagi El Waer

Electronic Theses and Dissertations

Removal of Tamarix spp. (a.k.a. tamarisk, saltcedar, Athel) invasion is often involved in restoration of Western, riparian habitat; however monitoring of vegetation after removal is often neglected and thus opportunity for adaptive management lost. To address this need, I have conducted three and half years of monitoring vegetation response after invasive Tamarix removal in twenty-five sites on the East and Western Colorado, starting fall 2009. I am also comparing six different methodologies: Point intercept, line transect, nearest neighbor, meter-square quadrats, nested Whittaker plots, and densitometer with the objective of developing monitoring protocols that can be used by …

Evolution Of Xenopus Tropicalis Mc2r: Expression And Activation, Perry Victoria Davis

Electronic Theses and Dissertations

The structure and functional relationship between the melanocortin-2 receptor (MC2R) and adrenocorticotropic hormone (ACTH) is the most complex of the melanocortin gene family. Prior studies had been done on amniote tetrapod MC2Rs (e.g., mammals); this study analyzed the expression and activation of MC2R by an anamniote tetrapod, Xenopus tropicalis (xtMC2R). An immunofluorescence approach, done on the expression of xtMC2R in Chinese Hamster Ovary cells (CHO cells), indicated that the trafficking of xtMC2R to the plasma membrane required co-expression with a tetrapod MRAP1(melanocortin-1 receptor accessory protein). A cAMP-reporter assay was used to show that xtMC2R can activated by human ACTH(1-24, but …

Role Of Camkii In Pancreatic Alpha Cells, Brooke A. Buckland

Electronic Theses and Dissertations

Calcium/calmodulin-dependent protein kinase II (CaMKII) has been identified as an important modulator in controlling electrical activity in neurons and the heart; however, a role for CaMKII in pancreatic alpha cell signaling has not been previously reported. Upon activation by calcium/calmodulin, CaMKII phosphorylates proteins involved in intracellular calcium homeostasis by inducing downstream effects such as an increase in AMPA-receptor single channel conductance, potentiation of L-type voltage dependent calcium channels, and enhanced surface expression of inhibitory GABA_A-receptors. In the pancreas, an increase in intracellular calcium drives secretion of glucagon from alpha cells within the Islets of Langerhans. α-cells contain many …

Regulating Rsma Expression In Pseudomonas Aeruginosa, Sean D. Stacey

Electronic Theses and Dissertations

Pseudomonas aeruginosa, a Gram-negative bacillus, commonly infects immunocompromised individuals and uses a variety of virulence factors to persist in these hosts. The posttranscriptional regulator, RsmA, plays a role in the expression of many virulence factors in P. aeruginosa. RsmA up regulates virulence factors used in colonizing hosts. However, regulation of rsmA is not well elucidated. Transposon mutagenesis was performed on P. aeruginosa containing a transcriptional rsmA-lacZ fusion to answer this question. Mutants were screened via β-galactosidase assay and transposon insertions identified via arbitrary PCR. A probable MFS transporter, we named mtpX, was one significant transposon mutant identified. …

Fossil Trachemys (Testudines: Emydidae) From The Late Hemphillian Of Eastern Tennessee And Its Implications For The Evolution Of The Emydidae, Steven E. Jasinski

Electronic Theses and Dissertations

Trachemys (Testudines: Emydidae) represents one of the most well-known turtles today. The evolution of Trachemys, while being heavily documented with various fossil representatives, is not well understood. Numerous fossils from the Gray Fossil Site in northeastern Tennessee are helping to elucidate the taxon’s evolution. The fossil Trachemys at the Gray Fossil Site represent a new species. A review of previously named Trachemys taxa reveals that a huge majority of them are not valid or have been previously misinterpreted. A phylogenetic analysis preformed on modern emydids and supposed fossil representatives of those genera also shows the evolution of a portion …

Variations In Phenotypic Plasticity And Fluctuating Asymmetry Of Leaf Morphology Of Three Quercus (Oak) Species In Response To Environmental Factors, Joseph Kusi

Electronic Theses and Dissertations

Leaf morphology of Quercus (oak) species is highly variable and complicated confounded with phenotypic plasticity and fluctuating asymmetry (FA). However, the study of variation is mostly limited to leaf morphology. This study was extended to plasticity and FA variations in Q. alba (white oak), Q. palustris (pin oak), and Q. velutina (black oak). It was hypothesized that light exposure, individual trees, leaf position, and other leaf traits will influence variation in these species. Leaves were sampled from trees of these species and their morphological traits were measured. Absolute asymmetry of leaf width and area were determined and plasticity of each …

Evolution Of Melanocortin-2 Receptor Activations: Studies On A Mammal And A Fish, Liang Liang

Electronic Theses and Dissertations

The structure and function relationship between melanocortin-2 receptor (MC2R) and ACTH are the most complicated in melanocortin receptor gene family. A comparative study on the activation of human and rainbow trout MC2R will provide a useful model system for understanding how ACTH emerged as the sole ligand for the MC2R of bony vertebrates. This dissertation will discuss how studies utilizing analogs of hACTH(1-24) have revealed two critical amino acid motifs in this ligand (HFRW and KKRRP) which are required for the activation of MC2R. In addition, the KKRRP motif functioned as the unique binding site for MC2R that directly contributes …

Mitochondrial Glutathione Transport: Implications For Bcl-2 And Neuronal Survival, Heather Marie Wilkins

Electronic Theses and Dissertations

Oxidative stress is a contributing factor to many neurodegenerative diseases. In particular, mitochondria are a key source of oxidative stress due to electron leakage at the level of the electron transport chain. To combat the endogenous production of reactive oxygen and reactive nitrogen species mitochondria are equipped with several redox-cycling systems, such as glutathione (GSH). Mitochondrial GSH has been shown to be a critical reservoir of this antioxidant, where selective depletion of mitochondrial GSH can induce apoptosis in several systems. Many studies have intricately linked Bcl-2 to cellular GSH status and it has been previously shown that Bcl-2 is a …

A Role For Dynamin-Dependent Endocytosis During Drosophila Gastrulation, Marissa Kay Kuhl

Electronic Theses and Dissertations

Gastrulation, a process conserved among many higher organisms, is the directed migration of cells into layers that will establish various tissues targeted to become anatomical structures. This process is accomplished through another conserved morphogenetic event, known as cell intercalation. Early in development, this movement of cells within an organized tissue leads to unique cellular arrangements where neighboring cells contract their shared interfaces in order to meet at a shared vertex. In this thesis, I present work that demonstrates a requirement for Dynamin-dependent endocytosis during these contraction events. Using quantitative analysis, I have identified varied cell behaviors during experiments which knockdown …

Testing For Indirect Benefits Of Polyandry In The Florida Green Turtle, Christopher Long

Electronic Theses and Dissertations

Behavioral studies in the green turtle (Chelonia mydas) have indicated that promiscuous mating is commonplace. Though it has been shown that there is much variation in the rate of polyandry (females mating with multiple males), the drivers behind polyandry in this species are unknown. It has been speculated, but never demonstrated, that indirect benefits (fitness benefits resulting from offspring genetic diversity) play a role. However, previous tests of this hypothesis have limited scope of inference due to lack of environmental control. In this thesis, I attempted to study the indirect benefits of polyandry in Archie Carr National Wildlife Refuge (ACNWR) …

Florida Local Government Conservation Planning: Variability, Drivers, And Policy Implications, Pamela Pannozzo

Electronic Theses and Dissertations

This study examined the quality of Florida county government conservation planning. To assess conservation planning quality, a theoretical model of conservation planning as prescribed by the conservation science literature was first developed. A plan evaluation coding protocol was applied to local comprehensive plan Conservation Elements to determine the extent to which county-level conservation planning met the theoretical model. A high degree of variability in conservation planning quality was found. Highest quality conservation planning occurred in the Gulf coast counties of southwest Florida. Lowest conservation planning quality occurred in the Florida Panhandle counties. The quality of conservation planning of coastal counties …

Sex Ratios Of Juvenile Green Turtles (Chelonia Mydas) In Three Developmental Habitats Along The Coast Of Florida, Cheryl Sanchez

Electronic Theses and Dissertations

The concept of temperature dependent sex determination (TSD) has been somewhat of an evolutionary enigma for many decades and has had increased attention with the growing predictions of a changing climate, particularly in species that are already threatened or endangered. TSD taxa of concern include marine turtles, which go through various life stages covering a range of regions. This, in turn, creates difficulties in addressing basic demographic questions. Secondary sex ratios (from life stages post-hatchling) were investigated by capturing juvenile green turtles (Chelonia mydas), 22.6-60.9 cm in straight carapace length (SCL), from three developmental areas along the east coast of …

Population Dynamics And Environmental Factors Influencing Herbs In Intact And Degraded Florida Rosemary Scrub, Elizabeth Stephens

Electronic Theses and Dissertations

Species have complex and contextual relationships with their environment; both the relative contributions of life-history stages to population growth and the effect of environmental factors on each stage can be different among co-existing species. Timing and extent of reproduction, survival, and mortality determine population growth, species distributions, and assemblage patterns. I evaluate the role of habitat (intact, degraded) and microsite (shrub, leaf litter, bare sand) on population dynamics of Florida scrub herbs. Isolated overgrown shrubs and extensive bare sand areas in degraded scrub were expected to decrease seed predation, reduce competition of herbs with shrubs, and provide larger habitat for …