Biology Commons^™

Genetic And Demographic Consequences Of Human-Driven Landscape Changes On Bird Populations: The Case Of Aphrastura Spinicauda (Furnariidae) In The Temperate Rainforest Of South America, Cintia Cornelius

Dissertations

Human activities, such as agriculture and forest exploitation, have modified landscapes worldwide. Despite a large accumulation of empirical and theoretical knowledge on habitat loss and fragmentation, some aspects remain poorly understood, especially those related to interactions between different forms of habitat degradation. The overall goal of this research was to study the effects of forest fragmentation and changes in forest structure on bird populations in a human-modified landscape in the temperate rainforest of South America using Aphrastura spinicauda (Furnariidae) as a model species. I evaluated i) if replacement of forest by open habitat leads to reduced dispersal influencing the genetic …

Pagamea Aubl. (Rubiaceae), From Species To Processes, Building The Bridge, Alberto Vicentini

Dissertations

Species delimitation have a great impact in scientific, environmental and other human activities, and is fundamental for understanding evolution. Plant species are usually delimited based on morphology and rarely species concepts are stated and analysis of variation made explicit. Botanists do see species as ?segments of evolutionary lineages?, but reproductive isolation is rarely addressed. Yet, reproductive isolation is necessary for understanding species, because speciation is the process of acquiring reproductive barriers. Almost any lineage will have species at different stages of isolation, and a single type of data will be insufficient for species delimitation. In plants, other biological processes such …

Mechanism Of Splicing Regulation By The Meiosis Enhancer Factor Mer1p In Yeast Saccharomyces Cerevisiae, Javier Armisen Garrido

Dissertations

In eukaryotes, genes are presented in a series of coding and non-coding DNA regions (exons/introns) that are transcribed into a premature RNA (pre-mRNA). Introns can be removed from the mature premRNA, before its translation into proteins, in a process called splicing. The splicing reaction occurs in two highly regulated transesterification reactions inside of the cell nucleus, and it is catalyzed by the Spliceosome, involving the binding and release of five small nuclear ribonucleoprotein particles (snRNPs). While some introns are constitutively spliced, others can be alternatively spliced, giving different exon combinations and therefore different proteins, increasing the protein diversity of the …

Seed Dispersal Limitation In A Neotropical Nutmeg, Virola Flexuosa (Myristicaceae): An Ecological And Genetic Approach, Kimberly Mae Holbrook

Dissertations

Seed dispersal contributes significantly to tropical forest maintenance, influencing processes, such as metapopulation dynamics and population persistence. Although several hypotheses have been debated regarding the contribution of seed dispersal to tropical forest diversity, recent work suggests that dispersal limitation is a major component in determining plant population patterns. This dissertation research broadly addresses hypotheses that seed dispersal behaviour of frugivores influences dispersal limitation of a Neotropical tree, Virola flexuosa (Myristicaceae). To test these hypotheses, I studied how different frugivores influenced seed dispersal of V. flexuosa at two sites in Amazonia Ecuador. General research objectives were to estimate fruit removal by …

Structure-Function Studies Of Self- Assembling Flagellin Proteins Fromsalmonella Typhimurium And Aquifex Pyrophilus, Venkata Raghu Ram Malapaka

Dissertations

The eubacterial flagellum is a complex structure with an elongated extracellular filament that is primarily composed of a single protein termed flagellin. The highly conserved N-and C- termini of flagellin are important in its export and assembly, whereas the middle "hypervariable" region is highly variable in size across different species and is largely dispensable. InSalmonella typhimurium phase 1 flagellin (FliC), this hypervariable region encodes two solvent-exposed D2 and D3 domains. The functional role of this knob-like structural feature in motility remains unclear. The structural and physiological role of the hypervariable region in flagellar assembly, stability and cellular motility was investigated. …

Comparative Immune Function In Wild Birds, Kevin David Matson

Dissertations

Over the last several decades, interest in quantifying immune function in comparative studies of wild animals has grown appreciably. Now, the field of ecological immunology is undergoing a transition, and ¿second generation¿ studies are being designed and carried out. With a greater appreciation of the complexity of immune systems, these second generation studies are commonly distinguished from their antecedents by making comparisons using multiple assays and including multiple species. I worked to advance this transition by developing novel approaches to comparative immunology, exploring the interrelationships among indices of immune function, and applying multiple indices to a question of comparative avian …

The Role Of Local And Regional Factors In The Foraging Ecology Of Birds Associated With Polylepis Woodlands, Grace Patricia Servat-Valenzuela

Dissertations

Understanding the extent to which patterns of functional structure are repeated in space and the scale at which different factors (local and regional) operate to explain community patterns are of important in community ecology. I studied the extent of spatial variation in foraging ecology of birds in the Polylepis community, a vegetation system of the Andes, in regard to variation in local (vegetation structure, floristic composition, food resources) and regional factors (biogeography). Specifically, I studied foraging ecology of nine insectivorous bird species (and the assemblage they conform) across twelve disjunct woodlands embedded in three biogeographic regions of the Peruvian Andes. …

Characterization Of Membrane Potentials In Vascular Smooth Muscle Of Hagfish, Lamprey And Trout, Prentiss Jones Jr.

Dissertations

The objective of this study was to characterize membrane potentials in systemic arteries of Pacific hagfish, Eptatretus stouti, Rainbow trout, Onchorhyncus mykiss, and Sea lamprey Petromyzon marinus. Previous studies have characterized membrane potentials in piscine tissue. However, these studies utilized non-vascular tissues such as cardiac muscle and skeletal muscle (69, 161). Characterization of membrane potentials in fish vasculature is without precedent in the literature. The hypothesis of this study was that membrane potentials in fish vascular smooth muscle differ little between species when comparable vasculature is evaluated.

Biogeography Of Buarremon Brush-Finches (Aves, Emberizinae): Integrating Ecology, Evolution, And Systematics, Carlos Daniel Cadena

Dissertations

Ecological and historical approaches to studying species¿ geographic ranges have yet to be unified. Ideal scenarios for integrating ecology with evolutionary biology in biogeography are those where contemporary ecological interactions may have influenced species¿ distributions historically, driving the evolution of ecological niches. I focused on understanding the origin of elevational distributions of species, and specifically on the role of interspecific competition in the origin of complementary elevational ranges. To test hypotheses about the origin of elevational distributions, I followed a combined approach involving molecular phylogenetics, phylogeography, population genetics, and ecological niche modeling. I focused on Buarremon torquatus and B. brunneinucha …

Exposure Of Nervous System Cells To Polychlorinated Biphenyls (Pcbs), Results In Alterations Of Neurotrophic Factor Expression, Gordon H. Gurley

Dissertations

Toxic insult by PCBs results in learning and memory deficits in humans. Alterations in expression of neurotrophic factors (NF) and/or their receptors have been linked to changes in learning and memory. How PCBs affect cognition is not known. We suggest that PCBs affect cognition by altering NF expression.

We exposed cultured C6 rat glioblastoma cells (an astrocyte cell-line) to medium containing PCB (Aroclor 1254 (10ppm)). Control cells were treated with dimethyl sulfoxide (DMSO) or regular medium. Enzyme-linked immunosorbent assays (ELISA) were used to determine glial cell-line derived neurotrophic factor(GDNF) and nerve growth factor (NGF) concentrations in all samples. We also …

Molecular Analysis Of The Effects Of Atrazine On Xenopus Laevis Frogs, Ronald Edward Celestine

Dissertations

Atrazine, the most commonly used herbicide in the U.S., has been implicated as one of the factors that may be causing the worldwide decline of amphibians. First, I examined effects of atrazine on laboratory raised Xenopus laevis tadpoles, treated from 5 days post fertilization to NF stage 65/66 with a concentrationof 25 ppb of atrazine. This study showed no significant difference in body weight, length and metamorphic rate.

Second, I used DNA microarrays to examine mRNA expression levels of genes in atrazine treated and control Xenopus laevis tadpoles. I found significant changes in gene expression levels of 18 genes. These …

Evolutionary Epidemiology Of Endemic Gal¿Pagos Birds And Their Parasites, Noah Kerness Whiteman

Dissertations

In order to better understand parasite diversification, I went to the Gal¿pagos Islands to study the ecology and evolution of a model bird-parasite system, which included four phylogenetically independent ectoparasite lineages infecting the Gal¿pagos Hawk (Aves: Buteo galapagoensis). The parasites comprised two lice (Insecta: Phthiraptera: Amblycera, Ischnocera), a lousefly (Diptera: Hippoboscidae) and an avian skin mite (Acari: Epidermoptidae). Ultimately, my goal was to examine ectoparasite evolutionary epidemiology and disease susceptibility in relation to the host¿s ecological and colonization history. At the outset, I hypothesized that parasite natural history was key in influencing the coalescent process. Accordingly, I found differences …

Comparative Genomic Analyses And Expression Of A Set Of Overlapping Open Reading Frames Of Frog Virus 3, Type Species Of Ranavirus (Family Iridoviridae), Wendy Guat Hoon Tan

Dissertations

Frog virus 3 (FV3) is the type species member of the genus Ranavirus (family Iridoviridae ). To better understand the molecular mechanisms involved in the replication of FV3, including transcription of its highly methylated DNA genome, the complete nucleotide sequence of the FV3 genome has been determined. The FV3 genome is 105, 903 base pairs long excluding the terminal redundancy. The G+C content of FV3 genome is 55% and it encodes 98 non-overlappingpotential open reading frames (ORFs) containing 50 to 1293 amino acids. Eighty-four ORFs have significant homology to known proteins of other iridoviruses, whereas 14 are unique FV3 ORFs. …

Olfactory Bulb Neurons Of Adult Zebrafish Morphology, Distribution, Cellular Interactions And Structural Stability Following Deafferentation, Cynthia L. Fuller

Dissertations

The zebrafish is becoming an increasingly popular model for studies involving olfactory function, yet there is still much to be learned about the anatomy and circuitry of different cell types in the olfactory bulb. This study focuses on identifying the morphology and distribution of output neurons and interneurons in the olfactory bulb of adult zebrafish, Danio rerio . Furthermore, this investigation examines the cellular interactions of the primary output neuron, the mitral cell, and addresses the issue of neuronal plasticity by considering the structural stability of this cell type following loss of afferent innervation.

Using retrograde tract tracing with various …

Ranging Patterns And Habitat Utilization Of Northern River Otters, Lontra Canadensis, In Missouri: Implications For The Conservation Of A Reintroduced Species, Deborah Dorothy Boege-Tobin

Dissertations

I studied the spacing patterns and habitat utilization by reintroduced northern river otters, Lontra canadensis, at two sites in Missouri because previous studies of otters indicate, plasticity of a species social structure will likely be due to the tactics employed in acquiring resources in any given area. Seven hypotheses were tested by employing radio-tracking, habitat assessment and geographic information system approaches: (1) home range (HR) and core area (CA) size differ by sex; (2) HR and CA size differ in breeding vs. non-breeding seasons; (3) percent range overlap differs by sex; (4) habitat utilization, as indicated by latrine use, …

Bioinformatics Study Of Mammalian Mrna Polydenylation, Haibo Zhang

Dissertations

Messenger RNA polyadenylation is one of the key post-transcriptional events in mammalian cells, which have influences on many aspects of mRNA metabolism. Several human diseases have been shown to associate with abnormal polyadenylation, highlighting the importance of this process. The availability of the complete sequence of human and mouse genomes, together with their gene expression data provides valuable resources to study mRNA polyadenylation on a system level. This dissertation addresses the following issues of mammalian mRNA polyadenylation through bioinformatics approaches: (1) the extensive documentation of several key aspects of polyadenylation sites in humans and mice on a genomic level; (2) …

The Role Of Puf3 Protein Interactions In The Regulation Of Mrna Decay In Yeast Saccharomyces Cerevisiae, Shervin Sean Houshmandi

Dissertations

The regulation of messenger RNA (mRNA) metabolism is an important step in proper gene expression. In many eukaryotic organisms this regulation can be mediated by a group of highly conserved RNA-binding proteins known as the Puf family of proteins. The yeast Saccharomyces cerevisiae has several proteins that belong to this family. One of the yeast Puf proteins, Puf3p, binds and regulates the COX17 mRNA, which codes for a protein involved in mitochondrial copper transport. Specifically, Puf3p stimulates the decay of COX17 mRNA. However, the precise mechanism of Puf3p binding and decay regulation is yet unknown. The goal of this research …

The Glucose And Insulin Responsiveness Of The Rat Glucose-6-Phosphate Dehydrogenase Promoter, Daryl Arkwright-Keeler

Dissertations

The regulation of expression of some enzymes involved in glucose homeostasis and fat metabolism requires both insulin and glucose to elicit an effect, while the regulation of others requires only one. Glucose-6-phosphate dehydrogenase (G6PDH), an important enzyme involved in glucose homeostasis, has been shown to be transcriptionally regulated by carbohydrate feeding in rat liver, a diet regime that increases the levels of both glucose and insulin. Our lab had previously shown that insulin induces expression of G6PDH, thus we wanted to determine if glucose also induced G6PDH expression and if so, are the glucose and insulin responses mediated through identical …

Bufadienolides In The Chemical Defenses Of The Toads, Bufo Americanus And Bufo Fowleri, Catherine E. Merovich

Dissertations

I investigated the steroidal chemical defenses (bufadienolides) of Bufo americanus and Bufo fowleri. By the nature of their complex, biphasic life cycles, toads, like other amphibians are important components of aquatic and terrestrial habitats and are prey to numerous invertebrates and vertebrates. Bufadienolides are presumed to be important anti-predatory compounds although much of their chemical ecology is poorly understood. I investigated (1) ontogenetic variation in bufadienolides, (2) bufadienolides from adult parotoid secretion, (3) effectiveness of bufadienolides against a terrestrial predator, and (4) effectiveness of bufadienolides against an aquatic predator. I hypothesized that B. americanuswould have a more extensive …

Changes In Glial Cell Line Derived Neurotrophic Factor And Nerve Growth Factor Expression With Development, Age, Exercise And Hypertension, Bertha C. Rebimbas-Cohen

Dissertations

Neurotrophic factors are important for neuronal growth, survival, and maintenance of cell phenotype. Glial cell line-derived neurotrophic factor (GDNF) affects sensory, autonomic and somatic motor neurons and nerve growth factor (NGF) affects sensory and sympathetic neurons. NGF and GDNF are produced by cardiac muscle and have potent effects on sensory and autonomic neuronal innervation of blood vessels. Neural innervation plays a key role in blood vessel function. Since neural innervation of blood vessels may be regulated by growth factors, we wanted to determine what changes would occur to NGF and GDNF levels with maturity, exercise and hypertension.

Changes in GDNF …

Non-Parametric Algorithms For Evaluating Gene Expression In Cancer Using Dna Microarray Technology, Virginie Aris

Dissertations

Microarray technology has transformed the field of cancer biology by enabling the simultaneous evaluation of tens of thousands mRNA expression levels in a single experiment. This technology has been applied to medical science in order to find gene expression markers that cluster diseased and normal tissues, genes affected by treatments, and gene network interactions. All methods of microarray data analysis can be summarized as a study of differential gene expression. This study addresses three questions, 1) the roles of selectively expressed genes for the classification of cancer, 2) issues of accounting for both experimental and biological noise, and 3) issues …

K+- Induced Dilation Of Cremasteric Arterioles Involves Na+/K+Atpase And Inward Rectifier K+ Channels, Wendy Burns

Dissertations

The purpose of this study was to evaluate the possible mechanisms involved in cremasteric arteriolar dilation as a result of increased concentrations of ([K⁺]_o) extracellular potassium. Many other studies suggested that Na⁺/K⁺ ATPase or K_IR channels are responsible for potassium-induced vasodilation in other systems (2, 12, 22, 40, 46, 52, 16, 17, 25, 33, 34, 85, 99, 151). However, these studies show only partial inhibition of dilation as a result of independent blockageof each mechanism. The hypothesis of this study was that both mechanisms contribute to potassium-induced dilation seen in cremasteric arterioles. …

Cellular Proliferation, Death And Histology In Gambusia Affinis Livers After Exposure To 2-Aminofluorene And Benzidine, Susan J. Lentz

Dissertations

A fundamental need exists for aquatic animals in the biomonitoring of aquatic ecosystems for environmental carcinogens. G. affinis, a small fish species, is selected for this study due to its hardiness, non-migratory nature, geographic diversity and ability to develop tumors. Molecular tools for cellular proliferation and death are examined for use with G. affinis. Additionally, these tools are used to investigate the early carcinogenic effects of 2-aminofluorene and benzidine, both individually and combined, on G. affinis livers.

Antibodies to proliferating cell nuclear antigen (PCNA), p53, cleaved caspase-3 and cleaved poly(ADP-ribose) polymerase (PARP) were examined for use in G. …

Molecular And Biological Characterization Of A Tanapox Virus Tnf-Binding Protein And The Complete Nucleotide Sequence Of The Psti-J Genomic Fragment, Mini Paulose-Murphy

Dissertations

Most of the poxvirus encoded virulence factors have been identified as proteins that are secreted from infected host cells. Some of these secretory proteins impede host immune defenses. We have previously demonstrated that tanapox virus (TPV) infected cells secrete a 38 kDa glycopeptide that binds to human (h) interferon-γ, h-interleukin (IL)-2, and hIL-5. We now show an additional activity in the supernatant from TPV infected cells that down-regulates the expression of tumor necrosis factor-a (TNF-α) induced cell adhesion molecule gene expression. This activity was not detected in mock infected cells. Enzyme linked immunosorbent assays (ELISA) on primary human endothelial cells, …

Identification And Classification Of Coryneform Bacteria Isolated From Bovine Mammary Glands, Jeffrey L. Watts

Dissertations

Coryneform bacteria are frequently isolated from bovine mastitis and these infections are associated with economic losses. Corynehacterium bovis, a lipid requiring species, has been the most frequently isolated coryneform from the milk of infected bovine mammary glands. However, the taxonomic status of this organism is uncertain. In the current study, a polyphasic approach was used to identify coryneform bacteria isolated from bovine mastitis and determ ine the phylogenetic relationships among the identified species. A total of 212 coryneform bacteria isolated from bovine mastitis was obtained from mastitis reference laboratories in the United States and Canada. Presumptive identification based upon …

Adaptation Of The Freshwater Benthic Diatom Achanthidium Rostratum To Resource Limitation, Patrick Daniel Donovan

Dissertations

No abstract provided.

Pathways Of Intracellular Protein Turnover In Cultured Human Fibroblasts, Sarah Olenick

Dissertations

No abstract provided.

A Study Of The Environmental Aspects Of Schistosomiasis In Libya, Abubaker I. Swehli

Dissertations

Schistosomiasis is a serious disease in humans. Two species of schistosome, Schistosoma mansoni and Schistosoma haematobium, organisms that cause the disease, parasitize humans in Libya. Schistosomes require aquatic snails in their life cycle. The purpose of this study was to investigate the environmental and the host relationships of the disease in the three regions of Libya where the disease is found. These relationships include:

1) Analyses of the physical-chemical characteristics of the aquatic habitat.

2) Collection of snails to determine: a) the kind of snail species and th e ir abundance; and b) the cercarial infestation rates.

3) Infection rates …