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Gonadal Histology And Reproductive Steroidogenesis Of Anurans Exposed To Potential Endocrine Disrupting Contaminants, Emily May La Fiandra

Doctoral Dissertations

The prevalence of malformed amphibians and the association of high incidences of malformation with the presence of environmental contaminants have raised questions about the effects of environmental contaminants on the development of larval amphibians. The potential endocrine disrupting effects of pesticides suggest that the reproductive and developmental abnormalities observed in larval anurans may be due at least in part to impacts on the hypothalamic-pituitary-gonadal axis. The present studies investigate the effects of exposure to environmental contaminants including DDT and atrazine on the development, gonadal histology and reproductive steroidogenesis of larval anurans.

As previous monitoring at Great Bay National Wildlife Refuge …

Structural Analysis Of Cytokine Signaling Modulators, Cristina Ileana Silvescu

Doctoral Dissertations

The N-linked glycans attached to cytokine receptors modulate signal transduction by interacting with galectin-3 and generating a cell surface lattice. This opposes constitutive endocytosis and reduces the thresholds for cytokine signaling. The preferred ligands for galectin-3 are the poly-N-acetyl lactosaminylated tetra-antennary glycans which are synthesized by Mgat 5 and are present at high levels in tumor cells. A null mutation in Mgat 5 inhibits lattice formation and cancer progression in cells with an oncogenic background. GlcNAc feeding reestablishes lattice formation, cytokine signaling and tumorigenesis.

A MALDI-TOF analysis was employed to identify the N-glycans involved in modulating signal transduction in wild …

Genetics And Physiology Of Motility By Photorhabdus Spp, Brandye A. Michaels

Doctoral Dissertations

Photorhabdus is a bacterial symbiont of soil nematodes and a lethal pathogen of insects. Many pathogenic or symbiotic bacteria utilize various methods of motility to reach favorable conditions, colonize a host, or have motility genes that also regulate virulence expression. It is not known how motility is regulated, or how it may confer an advantage, in the complex life cycle of Photorhabdus..

We characterized motility in Photorhabdus and found that the bacterium was motile both by swimming (movement in liquid) and swarming (movement on surfaces) under appropriate conditions. Both types of motility utilized the same peritrichous flagella and shared genetic …

Remote Detection Of Forest Structure In The White Mountains Of New Hampshire: An Integration Of Waveform Lidar And Hyperspectral Remote Sensing Data, Jeanne Elizabeth Anderson

Doctoral Dissertations

The capability of waveform lidar, used singly and through integration with high-resolution spectral data, to describe and predict various aspects of the structure of a northern temperate forest is explored. Waveform lidar imagery was acquired in 1999 and 2003 over Bartlett Experimental Forest in the White Mountains of central New Hampshire using NASA's airborne Laser Vegetation Imaging Sensor (LVIS). High-resolution spectral imagery from 1997 and 2003 was likewise acquired using NASA's Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). USDA Forest Service Northeastern Research Station (USFS NERS) 2001-2003 inventory data was used to define basal area, above-ground biomass, quadratic mean stem diameter and …

Cichlids As A Model For The Evolution Of Visual Sensitivity, Tyrone Clifford Spady

Doctoral Dissertations

The cichlid fishes of East Africa are the most ecologically diverse radiation of recent vertebrates. These highly visual fish live in habitats ranging from turbid rivers to clear lakes. They have evolved to exploit an astounding array of foraging strategies. The combination of phenotypic diversity and varied environmental conditions makes the cichlid system ideal for the examination of the relationship between ecology and the evolution of visual sensitivity. In this dissertation, I explore several aspects of this relationship. In Chapter 1, I compare the opsin gene sequences from 17 African cichlid species that have evolved in either clear or turbid …

Physiological Bases Of Parental Care In The Burying Beetles, Nicrophorus Orbicollis, Stefania Carmen Panaitof

Doctoral Dissertations

Burying beetles, Nicrophorus orbicollis, have extended biparental care. They bury and prepare small vertebrate carcasses as food for their young. While females provide the most care, single males show a remarkable behavioral compensation after a mate loss. Here, I integrate behavioral and physiological analyses of parental behavior in burying beetles by exploring how hormonal and social factors may interact to mediate brood care.

In Chapter I, I establish Juvenile Hormone (JH) profiles during a breeding bout and show that after larvae hatch, JH titers of single males and paired females are similar. JH titers of single males also respond to …

Improving Estimation Of Gross Primary Productivity Of Terrestrial Ecosystems, Qingyuan Zhang

Doctoral Dissertations

The MOderate Resolution Imaging Spectroradiometer (MODIS) provides an unprecedented opportunity to monitor and quantify seasonal changes of vegetation and phenology. MODIS has the potential to improve the estimation, which is based on the algorithms for the NOAA Advanced Very High Resolution Radiometer (AVHRR), of biophysical/biochemical variables of vegetation. My doctoral study improves estimation of gross primary productivity (GPP) through two aspects: first, my study improved the detection of vegetation phenology by distinguishing MODIS contaminated observations and contamination-free observations, and secondly, I inverted the fraction of absorbed photosynthetically active radiation (PAR) by chlorophyll using radiative transfer models and daily MODIS data. …

Functional Analysis Of The Caf1 Protein, Takbum Ohn

Doctoral Dissertations

The CAF1 protein is a component of the CCR4-NOT deadenylase complex. While yeast CAF1 displays deadenylase activity, this activity is not required for its function in vivo, and CCR4 is the primary deadenylase in the complex. In order to identify CAF1-specific functional regions required for deadenylation in vivo, we targeted for mutagenesis six regions of CAF1 that are specifically conserved among CAF1 orthologs. Defects in three regions of the CAF1 protein (residues 173-175, residues 255-257 and residues 340-342, alleles caf1-1, caf1-3 and caf1-6, respectively) were found to dramatically reduce the rate of deadenylation in vivo and to result in typical …

Patterns And Process During The Diversification Of The Cichlid Fishes In Lake Malawi, Africa, Michael R. Kidd

Doctoral Dissertations

The 500-1000 cichlid species endemic to Lake Malawi constitute one of the most rapid and extensive radiations of vertebrates ever discovered. The objective of this dissertation was to test the assumptions and predictions of several recently published models of cichlid speciation. First, a novel assay of female choice was used to evaluate the role of visual cues during conspecific recognition. The results of this experiment demonstrate that females are able to identify conspecific mates using only visual cues. Second, the assumptions of a recent model of speciation via intrasexual selection were tested by comparing aggressive behavior during territorial contests among …

Cellular Uptake And Actions Of Bilberry Anthocyanins In Retinal Pigment Epithelial Cells, Paul Everett Milbury Jr.

Doctoral Dissertations

Inflammation and oxidative stress play a significant role in the pathogenesis of age-related macular degeneration (AMD). In AMD, retinal pigment epithelium (RPE) cells are damaged by oxidative stress and die via the process of apoptosis. Anthocyanins from fruits and berries, such as bilberry (Vaccinium myrtillus), possess significant antioxidant activity in vitro and have been used in "traditional medicine" to treat AMD. It is not clear whether intracellular concentrations of anthocyanins are sufficient to quench radical species and mitigate oxidative stress in vivo. In this research project, human RPE cells in vitro were used to establish an oxidative stress model in …

Transposable Elements: What Have You Done For Me Lately? A Genomics Based Investigation Into The Potential Functional Roles Of Transposable Elements Using The Model Organism Caenorhabditis Elegans, Sarah Prescott Kenick

Doctoral Dissertations

The genomes of all organisms contain discrete DNA sequences present as disperse repetitive elements called transposons. Transposons have the unique ability to move to new chromosomal locations. Problems of uncontrolled movement of transposons can result in mutations, rearrangement, and even broken chromosomes. Often termed "selfish parasites" that invade a host genome, there is a longstanding question of whether they have a functional role. As a first step in an effort to investigate this question, I identified and annotated 276 full length and partial elements in the C.elegans genome. I determined the genomic location of each and looked for patterns resulting …

Ecological Patterns, Community Classification, And A Comparison Of Approaches For Predicting Biological And Habitat Reference Conditions In New Hampshire Streams, Brian R. Frappier

Doctoral Dissertations

Reference conditions play a vital role in many challenges facing both conservation and natural resources management. This dissertation sought to establish minimally-impacted reference conditions for stream biota and habitat in New Hampshire and explore alternative statistical methodologies to predict reference conditions for biological and habitat assessments. The fish, stream-dwelling salamander, macroinvertebrate and periphyton assemblages as well as the co-occurring physical habitat and riparian conditions of 76 minimally-impacted first to fourth order streams in New Hampshire were estimated using USEPA Environmental Monitoring and Assessment Program protocols over a four year period. Several statistical approaches and data standardizations for classifying multi-taxonomic assemblages …

Analysis Of The Role Of Poly(A) -Binding Protein (Pab1) In The Mrna Degradation Process In Yeast, Gang Yao

Doctoral Dissertations

The mRNA deadenylation process influences multiple aspects of protein synthesis and is known to be the major factor controlling mRNA decay rates. My data demonstrates that yeast PAB1 plays both positive and negative roles in controlling deadenylation, and I have identified particular regions of PAB1 involved in controlling different aspects of the mRNA degradative process. I have found that yeast PAB1 does not play a simple, obstructionist role in regulating CCR4 deadenylation. Instead, PAB1-PAB1 protein interactions, as mediated by the PAB1 proline-rich region (P domain) and the RRM1 domain, are required for the CCR4 deadenylase activity. The P and RRM1 …

Uptake And Growth Effects Of Polycyclic Aromatic Hydrocarbons In Wetland Plants, Alison Watts

Doctoral Dissertations

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants in estuarine environments, but little is known about the distribution and fate of PAHs in wetland sediments and plants. The effect of PAHs on common salt marsh plants, and the PAH distribution within the plants, sediment, and atmosphere were evaluated to determine if PAHs were transported from the sediment into the plants, and if the PAHs affected plant growth. Four salt marsh plant species, Spartina alterniflora, Phragmites australis, Solidago sempervirens and Distichlis spicata were grown in pots of PAH contaminated sediment containing mean total PAH concentrations of 355 mg/kg (ppm). During the growing …

Tropical Forest Structure: Ground Measurements Of Coarse Necromass And Satellite Observations Of Crown Geometry, Michael W. Palace

Doctoral Dissertations

Forests are structurally diverse, but these structures derive from the same processes of disturbance and growth. Understanding forest structure can help unlock the history, function, and future of a forested ecosystem. Components of forest structure include tree size distributions, foliage distributions and variation in canopy density, and coarse woody debris (coarse necromass). Tropical rainforests are structurally the most complex of all ecosystems. In addition to having high biological diversity, Amazon forests are marked by complex vegetation dynamics and a diverse forest stand structures, which play an important role in the interactions of water and carbon between the biosphere and atmosphere. …

A Molecular And Morphological Investigation Of The Red Seaweed Genus Porphyra (Bangiales, Rhodophyta) In The Northwest Atlantic, Troy Lee Bray

Doctoral Dissertations

To evaluate the possible occurrence of cryptic Porphyra taxa in the Northwest Atlantic, extensive field collections were made during winter and spring periods when relatively few previous collections had been made. Approximately 100 different sites extending from Chance Harbor, New Brunswick, Canada to Rye, New York, USA, were sampled during multiple years (2001-2005). Historical specimens from several herbaria (NHA, FH, BM, WTU, MICH, US) were also examined for possible cryptic taxa. A combination of morphological and molecular tools was used to screen both recent and historical collections.

Sequences from the plastid-encoded, ribulose-1, 5-bisphosphate carboxylase-oxygenase large subunit (rbcL) gene and rbcL- …