Digital Commons Network^™

Morphological Variation In Codium Fragile In The Northwest Atlantic, Lucy Elizabeth Pleticha

Master's Theses and Capstones

Codium fragile (Suringar) Hariot, an invasive Asiatic green alga, has colonized areas of the NW Atlantic within the past fifty years. The plant has a dichotomously branched cylindrical thallus made of tangled filaments surrounded by a dense covering of swollen filament tips, or utricles, terminating in pointed mucrons. This study's goal was to investigate morphological differences in NW Atlantic C. fragile populations to determine which subspecies are present. In the summer of 2008, I surveyed 24 sites from the Canadian Maritimes to Long Island Sound and evaluated size variation in utricles. Morphological investigations revealed a two-fold difference in utricle and …

Photosynthetic And Oxidative Stress In The Green Alga Dunaliella Tertiolecta: The Effects Of Uv-B And Uv-A Radiation, Priya Sampath Wiley

Doctoral Dissertations

The penetration of ultraviolet-B (UV-B; 290-320 nm) into the biosphere has increased in response to decreased stratospheric ozone. As a consequence, significant attempts have been made to elucidate the effects of UV-B radiation on primary producers such as phytoplankton and plants. Considerably less effort has been devoted to describing the role played by ultraviolet-A (UV-A; 320-400 nm) radiation, which is not attenuated by stratospheric ozone. The present work details the independent and combined effects of UV-B and UV-A radiation on photosynthetic and oxidative stress responses using the unicellular green alga Dunaliella tertiolecta as a model organism. A UV-B spectral profile …

An Assessment Of The Biodiversity And Bioremediation Potential Of Distromatic Ulva Spp (Chlorophyta) In The Great Bay Estuarine System Of New Hampshire And Maine, Usa, Laurie Carol Hofmann

Master's Theses and Capstones

Eutrophication of coastal ecosystems is a global problem, and algae have become an important resource for bioremediation. The goals of this study were (1) to assess the biodiversity of Ulva spp. in the Great Bay Estuarine System (GBES) of New Hampshire and Maine, and (2) to assess which Ulva populations are most appropriate for bioremediation by determining if environmental nutrient history and/or taxonomie differences affect ammonium uptake. Molecular analysis of the internal transcribed spacer nrDNA regions of Ulva spp. revealed four distinct distromatic taxa: Ulva lactuca Linnaeus, Ulva rigida C. Agardh, Ulva compressa Linnaeus, and U. pertusa Kjellman. The latter …

Extrapolating Hyperspectral Anthocyanin Indices To Multispectral Satellite Sensors---Applications To Fall Foliage In New England, Erica Lindgren

Master's Theses and Capstones

Anthocyanin, thought to be a universal indicator of plant stress, is a red pigment found in many plant species and can seen in New England autumns. Detecting its presence is useful for ecosystem analysis and monitoring changes during autumn senescence. Currently fall foliage is subjectively measured; creation of a satellite-based anthocyanin index will provide an objective measurement and enhance understanding of the distribution of plant stress and senescence over large areas. Anthocyanin indices were tested hyperspectrally in a laboratory setting, then indices were simulated for Hyperion, MERIS, MODIS, and Landsat TM/ETM+ to see which most accurately represents changes in anthocyanin …

An Assessment Of Stress In Acer Saccharum As A Possible Response To Climate Change, Martha Carlson

Master's Theses and Capstones

Climate change is projected to extirpate Acer saccharum throughout its range in the United States. The current investigation evaluates the potential of spectral indices of foliar reflectance, measures of leaf area and bud quality, and historic trends in sap sugar and wood increments for detecting stress in sugar maple.

Thirty trees were examined in 10 plots on 5 sugar bushes in or near the Bearcamp Valley, New Hampshire, over the course of the 2008 growing season. The study found water stress in 100% of trees; reduced chlorophyll content in 60%; early abscission of leaves in 80%; reduced growing season in …

Understanding Polyamine Metabolism Through Transgenic Manipulation In Poplar Suspension Cultures, Sridev Mohapatra

Doctoral Dissertations

Polyamines are low molecular weight aliphatic amines that are obligatory requirements for cell survival and growth. The commonly occurring polyamines in plants are putrescine, spermidine, and spermine. Suspension cultures of poplar (Populus nigra x maximowiczii), transformed with a mouse ornithine decarboxylase gene (under the control of a 2X 35S CaMV promoter) were used to study the impact of up-regulation of putrescine biosynthesis (and consequent enhanced catabolism) on several aspects of cellular metabolism. The transgenic cells were compared with a control cell line that was transformed with the beta-glucuronidase (GUS) gene.

It was observed that enhanced putrescine metabolism resulted in: (i) …

Identification And Characterization Of Protein Phosphatase 2a Mutants In Arabidopsis Thaliana, Enhua Wang

Doctoral Dissertations

Reversible protein phosphorylation is a highly regulated process that affects almost all cellular activities. Phosphorylation involves two groups of enzymes: protein kinases and protein phosphatases. Considering the central role of these enzymes in cells, elucidating their function is extremely important. My research focuses on protein phosphatase 2A (PP2A) C subunits. PP2A is one of the most abundant types of serine/threonine phosphatases in all eukaryotic cells. Compared with animals, PP2A function is not well known in plants. Early studies using protein phosphatase inhibitors are not useful to demonstrate the function of individual PP2A subunits. A reverse genetic approach can be helpful …

Survival Strategies Of Eelgrass In Reduced Light, Caroline A. Ochieng

Doctoral Dissertations

Light reduction due to anthropogenic impacts is the most widespread cause of worldwide decline of eelgrass, an ecologically important marine angiosperm whose role in supporting overall coastal ecosystem productivity has been widely recognized. Understanding eelgrass plant and meadow responses to light reduction has therefore received significant research interest over the last 30 years, while managers have sought tools to identify critical thresholds for light availability and predict impacts of human-induced disturbances in order to prevent further eelgrass loss. In the present thesis, a review of some of the literature on light reduction and its effects on eelgrass (i) summarized the …

Spectral Effects Of A Calcium Amendment On Red Spruce Foliage At Laboratory And Stand Scale, Will Robinson Kessler

Master's Theses and Capstones

Three sets of measurements were made to determine the effects of an October 1999 whole-watershed Ca-application on the chemical and spectral properties of red spruce (Picea rubens Sarg.) foliage at the Hubbard Brook Experimental Forest. Results of our measurements showed significant differences between the Ca-treated watershed (WS1) and a nearby reference watershed (WS6). Foliar chemistry data collected in 2007 showed that concentrations of Ca, Sr, and oxalate remain higher in WS1, and the increase in oxalate is strongly linked to the level of total Ca, possibly by a Ca-oxalate crystal precipitation response. High-resolution laboratory spectral data measured from 400-2500 nm …

Invasion Of Transition Hardwood Forests By Exotic Rhamnus Frangula: Chronology And Site Requirements, Hanna S. Wingard

Master's Theses and Capstones

The invasion chronology and site requirements of the exotic, invasive shrub, glossy buckthorn (Rhamnus frangula), were studied within intact transition hardwood---hemlock---white pine forests in Durham, NH. Data were collected from 63 plots (7 sites with 9 plots each). Within sites, plots were arranged over a topographic gradient with 3 plots in each of 3 topographic positions (upper, middle, and lower slope). From each plot, information on soil nutrients and texture, soil moisture, overstory community composition, and canopy openness was collected. Densities of R. frangula in two size classes (≥1 m in height, <1 m in height) within each plot were calculated. Morphological data (height, diameter at stem base, number of live and dead stems, and age) were collected from each individual ≥1 m tall. R. frangula invaded these intact, closed-canopy forests over 30 years ago and the invasion has continued, with population density increasing over time. Nominal logistic regression suggested that site, topographic position, and overstory community type played a role in whether or not R. frangula was present in a plot. Plots on upper slopes dominated by Tsuga canadensis were less likely to become invaded than other plots. Multiple linear regression showed that density of R. frangula (≥1 m) increased with time since invasion and increasing soil quality. Density of R. frangula (<1 m) was positively influenced by time since invasion, canopy openness, and density of R. frangula (≥1 m). Multiple regressions also showed that mean age and age of oldest R. frangula per plot were higher in plots with higher soil moisture content. Size of R. frangula individuals (i.e. height, diameter) generally increased with mean age of stems. The results show that successional, transition hardwood forests can be invaded by R. frangula and should not be overlooked when managing against this species. Special attention should be given to low topographic positions and areas with rich soils, while upland areas with dense hemlock canopy are much less likely to experience heavy invasion by R. frangula..

Fungal Glycosphingolipids: Characterization Of Structures And Interactions With Plant Defensins, Jis Joe

Master's Theses and Capstones

Glycosphingolipids (GSLs) play important roles in many fundamental biological processes like activation of signal transduction pathways, immune responses, and cell-cell interactions. Recent reports imply that fungal GSLs are important targets for the antifungal action of plant defensins. In order to study intermolecular interactions of GSLs, it is crucial to know their structures in detail. This thesis consists of two projects in which fungal GSLs of biological and biomedical significance are studied. In the first project, we have completed the structural characterization of acidic GSLs from S. cerevisiae using NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS). The second project of …

Investigation Of Cyanidin And Pelargonidin Contents In The Genus Fragaria L, Lise Bouchard Mahoney

Master's Theses and Capstones

Cultivated strawberry (Fragaria x ananassa ) fruit contain primarily pelargonidin and little cyanidin. The antioxidant potential of cyanidin is reportedly twice that of pelargonidin. A High Performance Liquid Chromatography method was developed to assay fruit anthocyanidin content in 87 Fragaria accessions, including wild diploids and octoploids, cultivars, and two segregating populations. A cyanidin to pelargonidin ratio (CPRatio) greater than one was found only in diploids Fragaria vesca ssp. americana (confirming a previous report), F. viridis, and F. iinumae, and in three wild octoploid accessions: all F. chiloensis. The highest cyanidin contents were found in diploid F. viridis and in F. …

Expression Profiling Of The Spermidine Synthase3 (Spds3) And Spermine Synthase ( Spms) Genes During The Life Of Arabidopsis, Charles F. Rice

Master's Theses and Capstones

Polyamines are low molecular weight nitrogenous compounds found in all living organisms. These omnipresent molecules have been extensively studied in plant systems and have been implicated in a number of physiological responses including growth, development, and stress response. The proposed role of polyamines in vital processes such as cell division and differentiation has sparked enthusiasm in further investigation of this relatively small biosynthetic pathway. Very little is known about the regulation of polyamine biosynthetic genes, an aspect that can elucidate further functions of these ubiquitous compounds. In the following study, the expression profiles of two of these genes, spermidine synthase3 …

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 …

Analysis Of Signal Output By The Ethylene Receptor Etr1 From Arabidopsis, Xiang Qu

Doctoral Dissertations

Ethylene is one of the most important plant hormones and regulates many processes during plant growth and development. In Arabidopsis, the ethylene receptor family consists of five members: ETR1 and ERS1 have a functional histidine kinase domain and form subfamily 1; members of subfamily 2, including ETR2, ERS2, and EIN4, possess a highly diverged histidine kinase domain predicted not to be functional. To analyze signal output by the ethylene receptor ETR1 from Arabidopsis, mutant-based approaches were taken. Initially, the role of the proposed signal output region of ETR1 in ethylene signaling was examined. For this purpose, the ability of mutant …

Calcium -Dependent Protein Kinases Are Myristoylated And Associated With Different Membranes In Arabidopsis Thaliana, Sheen Xun Lu

Doctoral Dissertations

In plants, calcium-dependent protein kinases (CDPKs) are the predominant calcium-stimulated kinases and are known to be involved in many cellular processes. CDPK enzymatic activity previously has been detected in many locations in plant cells, including the membrane fraction. However, little is known about the subcellular locations of individual CDPKs or the mechanisms involved in targeting them to those locations. Arabidopsis contains 34 genes that are predicted to encode CDPKs and 28 of the predicted CDPK proteins have potential myristoylation motifs at their amino termini. Myristate is a 14-carbon saturated fatty acid that is attached co-translationally to the amino-terminal glycine of …

Photoprotective Role Of Beta -Carotene And Antioxidant Enzymes: A Shield Against Ultraviolet Damage In Dunaliella Bardawil, Andrea Lynn Grossman-White

Doctoral Dissertations

Photosynthetic and antioxidant responses following exposure to an array of irradiances and frequencies were examined and contrasted in two species of the unicellular green alga Dunaliella. Species selection was based on the ability of Dunaliella bardawil (UTEX 2538) to accumulate massive quantities of inter-thylakoid beta-carotene during exposure to stress or high irradiances of photosynthetically active radiation (PAR: 400-700 nm) while Dunaliella salina (UTEX 200) lacks this ability. Cells were cultured in two irradiances (150 and 35 mumol photons ·m-2·s -1), and then exposed to high red (wavelengths > 590 nm) or blue light (390-540 nm; 150 mumol photons·m -2·s--1), ultraviolet-A (320-400 …

Regulation Of Ethylene Receptor Expression In Arabidopsis, Xue-Chu Zhao

Doctoral Dissertations

The ethylene receptor family of Arabidopsis consists of five members, ETR1, ETR2, ERS1, ERS2, and EIN4. Regulation of ethylene receptor expression in Arabidopsis was studied using three different approaches. First, the effect of ethylene-pathway mutations upon expression of ETR1 was examined. Ethylene-insensitive mutations in ETR1 resulted in a post-transcriptional increase in levels of the mutant receptor. Treatment of seedlings with silver, which leads to ethylene insensitivity, also resulted in an increase in levels of ETR1. Mutations in other components of the ethylene pathway had little effect upon expression of ETR1. Second, microarray analysis was performed using reciprocal mutants to examine …

Transgenic Manipulation Of Polyamine Metabolism In Poplar, Pratiksha Bhatnagar

Doctoral Dissertations

Polyamines are low molecular weight polycations found in all living organisms. They are involved in plant stress response and development. The study was aimed at analyzing the effects of altered polyamine metabolism on the polyamine and related pathways in transformed poplar cells overexpressing a mouse odc cDNA under the control of 2X 35S CaMV promoter. The transgenic cells (line 2E) showed elevated levels of mouse ornithine decarboxylase enzyme activity, several fold higher amounts of putrescine, a small increase in spermidine, and a small reduction in spermine as compared with non-transgenic (NT) cells. The conversion of labeled ornithine into putrescine was …

The Relationship Between Fruit Color Traits And Anthocyanin Genes In Diploid Fragaria, Chaoyang Deng

Doctoral Dissertations

A candidate gene approach was used to determine the likely molecular identity of the c locus (yellow fruit color) in Fragaria vesca, a diploid (2n = 2x = 14) strawberry. Using PCR with degenerate primer pairs, intron-containing segments of structural genes coding for the enzymes: chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR), anthocyanindin synthase (ANS), and one Del-like regulatory gene (RAN) in the anthocyanin biosynthetic pathway were amplified, cloned and sequenced. Intron length polymorphisms for each of these genes were detected among three diploid varieties: F. vesca Alpine variety 'Yellow Wonder' (YW) (Europe); DNIC, an …

Remote Sensing Of Forest Damage In The Czech Republic Using Hyperspectral Methods, Petya K. Entcheva

Doctoral Dissertations

The current study assesses the potential of hyperspectral data for monitoring the initial stages of damage in Norway spruce forests characterized by subtle changes in foliar chlorophyll and chemistry. Both field and airborne high spectral resolution reflectance measurements were obtained for selected study sites in the Krusne hory, Czech Republic.

High spectral resolution airborne canopy data and field foliar samples were acquired simultaneously in August 1998 for a total of 51 study sites within the Krusne hory. The sites were selected to represent a full range of damage conditions in even-aged Norway spruce (Picea abies (L.) Karst) stands located between …

Chilling Photoinhibition In Zea Mays L And Zea Diploperennis Iltis, Doebely And Guzman: The Role Of Oxygen And Antioxidants, Kajal Bose Ghoshroy

Doctoral Dissertations

Light absorbed by photosynthetic pigments must be distributed either for chemical work, reemitted as fluorescence or safely dissipated as heat. Adverse environmental conditions reduce the dissipation capacity of plants and the excess energy leads to damage to the photosynthetic mechanism, termed photoinhibition. Low, non-freezing temperatures cause such photoinhibition, especially in tropical plants grown in the temperate zone. This damage occurs in the photosystem II and is triggered by highly reactive radicals or reactive forms of dioxygen. Numerous studies point to the involvement of oxygen and antioxidant enzymes and substrates in amelioration of these damages. In C$\sb3$ plants, dioxygen is thought …

Genetic Engineering Of The Polyamine Biosynthetic Pathway And Somatic Embryogenesis In Carrot (Daucus Carota L), Dhundy Raj Bastola

Doctoral Dissertations

Ornithine decarboxylase (ODC), arginine decarboxylase (ADC), and S-adenosylmethionine decarboxylase (SAMDC) are three of the key regulatory enzymes involved in the biosynthesis of polyamines (putrescine, spermidine and spermine). To modulate the biosynthesis of putrescine, carrot (Daucus carota L.) cells were transformed with Agrobacterium tumefaciens strains containing 3$\sp\prime$-truncated mouse ornithine decarboxylase (ODC) cDNA under the control of a CaMV 35S promoter. Neomycin phosphotransferase gene linked with nopaline synthase promoter was used to select transformed cell lines on kanamycin. While the non-transformed cells contained no ODC, high levels of ODC activity were observed in the transformed cells. A significant increase in the cellular …

Steady-State Natural Fluorescence, Arnold Francis Theisen

Doctoral Dissertations

This study employed a manifold analytical approach to the application of multiple excitation and emission wavelengths of steady-state natural fluorescence for the detection of stressed and damaged vegetation. This investigator has attempted to answer questions put forth in terms of the following null hypothesis: Natural fluorescence emission, measured in the steady-state from living, attached or freshly excised needles of eastern white pine (Pinus strobus L.) or leaves of common beans (Phaseolus vulgaris L.), cannot be used in the form of complete spectra or in ratios of discrete wavelengths as indicators of stress from abiotic sources such as ozone or cadmium. …

Light Detection System In Higher Plant Chloroplasts: Pigment Mediated Or Overall Photon Flux Density Related, Soumitra Ghoshroy

Doctoral Dissertations

Plants adapt to short term changes in irradiance and quality of the light environment by modulating the structure of the thylakoid membranes to make the best use of the available light energy. Shade-acclimated chloroplasts develop more thylakoid surface area as compared to those growing in full sunlight. Conversion of sun-type chloroplasts to shade-types and vice versa on the basis of total thylakoid membrane surface area can occur quickly. However, the response mechanism of chloroplasts to changes in light levels is yet to be understood. This short term light detection mechanism may be mediated by a pigment system other than photosynthetic …

Strawberry Malformation And The Tarnished Plant Bug, David Thomas Handley

Doctoral Dissertations

Experiments were designed to study the malformation of strawberries, Fragaria x ananassa (Duchesne) caused by the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois). In greenhouse experiments, duration of blossom exposure to tarnished plant bug affected the type of malformation observed. Exposure at anthesis for 48 hours was most likely to cause apical seediness, the malformation associated with tarnished plant bug. The number of nonviable achenes per fruit increased with longer feeding durations. Malformation was also affected by blossom stage. Prebloom feeding caused blossom death. Feeding at petal fall or achene separation resulted in malformations, including apical seediness. Feeding at …

Expression Of The Murine Ornithine Decarboxylase Gene In Transgenic Nicotiana Tabacum Var Xanthi, Richard Anthony Descenzo

Doctoral Dissertations

Ornithine decarboxylase (ODC), arginine decarboxylase (ADC), and S-adenosyl-methionine decarboxylase (SAMDC) are the three key regulatory enzymes for polyamine (putrescine, spermidine, and spermine) biosynthesis. In order to gain more insight into the relationship between polyamine metabolism and other physiological processes, research was undertaken to obtain increased putrescine biosynthesis in tobacco by overexpression of a murine ODC cDNA.

Both a full-length and a truncated murine ODC cDNA were cloned into a binary expression vector containing the Cauliflower Mosaic Virus (CaMV) 35S promoter. Using standard leaf-disc transformation procedures, transgenic tobacco plants containing either the full length or the truncated ODC cDNA were obtained. …

Genetic, Physiological And Anatomical Analyses Of A Wilty Mutant In Tomato (Lycopersicon Esculentum Mill, Cv Large Plum), Karen Elizabeth Rasmussen

Doctoral Dissertations

Large Plum', a tomato cultivar carrying a wilty mutation (LP-wilty), was characterized genetically, physiologically, and anatomically. Inheritance, complementation, and mapping studies of LP-wilty were performed. The mutation was found to be inherited as a single dominant gene, distinct from other wilty alleles, and was mapped to the long arm of chromosome six.

Measurements were taken of stomatal conductance, root conductance, shoot water potential, and leaf water potential for 'Large Plum' and normal plants. Results suggest that both stomatal conductance and root conductance rates are reduced in the wilty mutants. In addition, shoot and leaf water potentials are more negative in …

Rowcover Modification Of Carbon And Mineral Nutrient Partitioning In Strawberry (Fragaria Ananassa, Duch), Karen Lynn Brownlee Gast

Doctoral Dissertations

In cool temperature climates where plant growth may be limited by short growing seasons and low temperature stress rowcovers are being used to increase production of fruit and vegetable crops. Two field experiments were conducted to investigate how floating rowcovers applied during autumn, winter and spring affect plant growth and development. The first experiment, 1985-86, examined mineral nutrient and biomass partitioning in a short-day cultivar, 'Sparkle', and a day-neutral cultivar, 'Fern', in rowcovered and nonrowcovered plants in autumn. The second experiment, 1986-87 examined carbon, nitrogen and biomass partitioning over time in autumn and in spring and development of yield components …

Genetics And Physiology Of Cold Tolerance In Muskmelon (Cucumis Melo L), Mark Gordon Hutton

Doctoral Dissertations

Five hundred muskmelon accessions were evaluated for germinability at 15$\sp\circ$C and classified as cold germinable (CG) or non-cold germinable (NCG). Accessions meeting the following criteria were classified as CG: germination $>$80%, EI $\leq$ 240, HI $\leq$ 265, and CI $\leq$ 290. EI, HI, and CI are mean hours to emergence, hypocotyl elongation and cotyledon expansion respectively. Only 5% of the accessions examined were considered as CG.

Seedling growth of CG (PI 126156, PI 126197, and 'Persia 202') and NCG ('Delicious 51', 'Minnesota Midget', 'Old Time Tennessee', Russian 4141) muskmelon genotypes was compared. Seedlings were grown to 30$\sp\circ$C to the …