Digital Commons Network^™

Film Formation By Marine Bacteria At A Model Fluid Interface, Vera Zutic, Nadica Ivosevic, Vesna Svetlicic, Richard A. Long, Farooq Azam

Faculty Publications

We have characterized the nonspecific interactions in the initial attachment and film formation by marine bacteria at a dynamic fluid interface: seawater/dropping mercury electrode. Experimental evidence is presented that bacteria readily establish molecular contact with the metal substrate without mediation of a conditioning film. Prevalence of hydrophobic over electrostatic interactions and the possible importance of Ca²⁺ bridging could be inferred. The attachment of individual bacterial cells is faster than their transport from the aqueous medium, as is the case in the transport-controlled adsorption of biopolymers. The cell aggregates yield distinct electrical attachment signals, allowing a comparison between cell-cell and …

Regulation Of The Gbn-1 Transcript During Vegetative Growth And Macrocyst Development In Dictyostelium., Jodi R. Hall

Student Work

A transcript corresponding to the gene gbn-1 has been found in Dictyostelium mucoroides during vegetative growth and microcyst development. The nucleotide and amino acid sequence is known, and the amino acid sequence was found to be 65% similar and 50% identical to a hemoglobin protein found in the bacterium Vitreoscilla. The purpose of the study was to further characterize the gbn-1 gene activated during development of microcysts. The transcript was found in Dictostelium cells during the vegetative stage and during microcyst development. Quantitative results, using 18S rRNA as an internal control, on the microcyst cells. Later developing cells still produced …

Dissolved Organic Carbon Cycling In A Subtropical Seagrass-Dominated Lagoon, Susan Ziegler, Ronald Benner

Faculty Publications

The cycling of dissolved organic matter (DOM) and its significance to ecosystem metabolism was studled over a 16 mo period in a Thalassia testudjnum dominated meadow. The benthos was usually net autotrophic (annual gross primary production to respiration ratio [P:R] = 1.3) while water column respiration (R) exceeded gross primary production (annual P:R = 0.3). Net fluxes of dissolved organic carbon (DOC) from the benthos primarily occurred in the light (0 to 18 mmol C m^-2 d^-1) and from seagrass-dominated areas, suggesting that release of DOC was mainly due to seagrass exudation. Net benthic DOC fluxes measured …

The Reproductive Biology And Edaphic Characteristics Of A Rare, Gynodioecious Saxifage: Saxifraga Bryophora Var. Tobiasiae (Saxifragaceae), Kimberly Pierson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

I examined the reproductive biology and general ecology of Saxifraga bryophora var. tobiasiae, a rare saxifrage endemic to the West Salmon River Mountains of central Idaho. Saxifraga bryophora var. tobiasiae combines asexual reproduction via bulbils with a sexual mixed-mating system. Flower production occurred in 1996 only, whereas bulbil production occurred in 1995, 1996, and 1997. Bulbil production precedes floral bud formation and is the dominant form of reproduction. When flowering occurs, outcrossing is promoted by protandry and the gynodioecious mating system found in all populations. No autogamous or agamospermous seed set was observed in either female or hermaphrodite flowers, …

Coupling Between Bacterioplankton Species Composition, Population Dynamics, And Organic Matter Degradation, Jarone Pinhassi, Farooq Azam, Johanna Hemphälä, Richard A. Long, Josefina Martinez, Ulla Li Zweifel, Åke Hagström

Faculty Publications

To study the effect of substrate addition on short term bacterial population dynamics and species composition in seawater mesocosms were maintained with water collected off Scripps Pier (La Jolla, California USA) Protein enrichment (BSA) triggered a dynamic response from the microbial food web, whereas enrichment with starch had no effect. In the protein enriched mesocosm the number of both nucleoid-containing cells and metabolically active cells increased by 3.0 X 10⁵ cells ml^-1 from Day 1 to Day 4 In the same time period the density of a set of 31 phylogenetically different bacteria (α- and g-Proteobactena as well …

Rainfall Stimulation Of Primary Production In Western Atlantic Ocean Waters: Roles Of Different Nitrogen Sources And Co-Limiting Nutrients, Hans W. Paerl, Joan D. Willey, Malia Go, Benjamin L. Peierls, James L. Pinckney, Marilyn L. Fogel

Faculty Publications

Using shipboard bioassays, we examined the roles rainfall, individual and combined nutrients play in accelerating primary production in coastal, Gulf Stream and pelagic (Sargasso Sea) locations in the North Atlantic Ocean off North Carolina, USA, from 1993 to 1995. Photosynthetic CO₂ fixation and net chlorophyll a (chl a) production were measured In replicated bioassays to assess individual and combined impacts of different constituents of atmospheric deposition, including natural rainfall, a synthetic rain mix, dissolved inorganic nitrogen (DIN; NH₄⁺ ,NO₃^-), dissolved organic nitrogen (DON; urea),phosphorus (PO₄^3-) and iron (as EDTA-chelated and …

Mechanisms Of Immunotherapeutic Intervention By Anti-Cd40l (Cd154) Antibody In An Animal Model Of Multiple Sclerosis, Laurence M. Howard, Amy J. Miga, Carol L. Vanderlugt, Mauro C. Dal Canto, John D. Laman, Randolph J. Noelle, Stephen D. Miller

Dartmouth Scholarship

Relapsing experimental autoimmune encephalomyelitis (R-EAE) in the SJL mouse is a Th1-mediated autoimmune demyelinating disease model for human multiple sclerosis and is characterized by infiltration of the central nervous system (CNS) by Th1 cells and macrophages. Disease relapses are mediated by T cells specific for endogenous myelin epitopes released during acute disease, reflecting a critical role for epitope spreading in the perpetuation of chronic central CNS pathology. We asked whether blockade of the CD40–CD154 (CD40L) costimulatory pathway could suppress relapses in mice with established R-EAE. Anti-CD154 antibody treatment at either the peak of acute disease or during remission effectively blocked …

Reproductive Biology And Search Behavior Of Amitus Bennetti (Hymenoptera: Platygasteridae), A Parasitoid Of Bemisia Argentifolii (Homoptera: Aleyrodidae), Andrea L. Joyce, Thomas S. Bellows, Jr., David H. Headrick

Horticulture and Crop Science

No abstract provided.

Evolution Of Pycnogonid Life History Traits, Eric Carl Lovely

Doctoral Dissertations

The Pycnogonida is a class of arthropods with interesting life histories. Pycnogonids prey on hydroids and some invade hydranths while larvae. Males brood the eggs and larvae hatch as protonymphons. Questions relating to the evolution of life history characteristics were addressed. Evolutionary relationships were poorly understood. It was necessary to determine the relationships within the Pycnogonida and compared to other arthropods.

Twenty-four morphological characters were coded for twenty-three pycnogonid genera and one fossil ancestor, Palaeoisopus problematicus. A branch and bound analysis resulted in fifteen most parsimonious trees. The Nymphonidae were found to be basal. The Ammotheidae were paraphyletic and led …

The Effect Of Physical And Biological Site Characteristics On The Survival And Expansion Of Transplanted Eelgrass (Zostera Marina L), Ryan Clark Davis

Doctoral Dissertations

Eelgrass (Zostera marina L.) was transplanted at seven sites along the New Hampshire side of the Piscataqua River in 1993 and 1994. The eelgrass transplanting was one component of the New Hampshire Port Authority Mitigation Project, designed to mitigate for impacts to natural resources associated with the expansion of the port facility. Over 2.5 hectares of eelgrass were transplanted using a newly developed transplanting technique, the horizontal rhizome method, and ultimately created eelgrass habitat at several sites. However, transplants did not survive at any of the intertidal areas planted and were greatly reduced at several subtidal sites. The intertidal transplants …

The Long-Term Effects Of Disturbance On Nitrogen Cycling And Loss In The White Mountains, New Hampshire, Christine Lynn Goodale

Doctoral Dissertations

Theories of nitrogen retention suggest that N cycling and loss should increase with ecosystem successional age and with chronic N deposition over time (N saturation). These factors both affect northeastern U.S. forests, most of which receive elevated rates of N deposition and have experienced past disturbances by wind, logging, fire, or agriculture. This work examined the long-term (80--110 year) effects of land-use history on nitrogen cycling and loss in the White Mountains, New Hampshire. Historical land-use maps were used to identify a network of watersheds and plots containing burned, logged, or old-growth forests. Nitrate-N fluxes from old-growth watersheds exceeded those …

Effects Of Intralaminar Thalamic Nuclei, Prefrontal Cortical, And Hippocampal Lesions On A Seven-Choice Serial Reaction Time Task, Joshua Alan Burk

Doctoral Dissertations

Slow response speed has been associated with several neuropsychological disorders including Korsakoff's disease. The ability to respond to brief stimuli can be tested to assess whether slow response speed is due to slow stimulus processing. A seven choice serial reaction time task was developed to test the ability to respond to brief stimuli. Distractibility and stimulus discriminability were manipulated to challenge performance and cues were presented to enhance performance. In Experiment 1, six unlesioned rats were tested on this task. As expected, significant deficits were found when (1) stimulus duration was decreased, (2) bright distractor light was briefly presented, (3) …

Functional Characterization Of The Ccr4-Not Transcriptional Regulatory Complex, Vasudeo Badarinarayana

Doctoral Dissertations

The CCR4-NOT transcriptional regulatory complex affects expression of a number of genes both positively and negatively. This study demonstrates that the CCR4-NOT complex functionally and physically interacts with TBP and TAFs. Firstly, mutations in CCR4, NOT4, and NOT5 suppressed the his4-912 delta insertion by a mechanism similar to that observed for the defective TBP allele spt15-122. This mechanism appeared to involve stabilization of TBP binding to a specific non-consensus TATA sequence, CATAAA, in the his4-912 delta element. Secondly, using modified HIS3 promoter derivatives containing specific mutations within the TATA sequence, it was found that the NOT proteins were general repressors …

Effects Of Repeated Restraint Stress On Tissue Metabolism In Rats., Jun Zhou

LSU Historical Dissertations and Theses

It has been reported that repeated restraint stress (RS), 3 hours/day for 3 days, in rats caused sustained weight loss and a temporary drop in daily food intake with no subsequent compensatory overeating during the post stress period. The hypothesis tested in the present study is that RS causes peripheral tissue metabolism changes which account for the abnormal regulation of body weight and food intake during the post stress period. Adult male Sprague Dawley rats were assigned to control, pair fed (PF) or RS groups. One day after the end of RS, midbrain urocortin mRNA was at control levels in …

Influence Of Environment And Genotype On The Expression Of Host Plant Resistance In Sweet Potato To The Sweet Potato Weevil, Cylas Formicarius (Fab.)., Lixin Mao

LSU Historical Dissertations and Theses

Field and laboratory experiments were conducted to study the influence of environment and genotype on the expression of sweetpotato resistance to the sweetpotato weevil (SPW), Cylas formicarius (Fab.). Roots of four genotypes ("W-244", "W-250", "Beauregard", "Centennial") were evaluated for SPW feeding and oviposition at three different storage times. Roots from Louisiana, South Carolina and Mississippi were also evaluated. Genotype had a significant effect on feeding and oviposition. Storage time and production sites appeared to affect resistance expression; the outcomes depend on the genotypes. The effect of nitrogen on sweetpotato resistance to SPW was studied. Four genotypes were grown in the …

Isolation And Characterization Of A Caenorhabditis Elegans Src Loss-Of-Function Allele Using Reverse Genetics, Jennifer Dignan Hogan

Doctoral Dissertations

The vertebrate proto-oncogene Src is a protein-tyrosine kinase that has been implicated as a component of receptor-mediated signal transduction pathways important for cell growth and differentiation. Consistent with this notion, overexpression or activation of Src by mutation induces neoplastic transformation in cell culture, leads to tumorigenesis in laboratory animals, and has been observed in a number of human tumors. Despite years of intensive investigation, neither its role in oncogenesis nor its normal, biological role is understood.

To diminish the issue of redundancy that has complicated analysis of Src function in vertebrates and Drosophila, I have chosen to study Src function …

Behavioral And Physiological Responses Of The Lobster, Homarus Americanus, To Temperature: A New Synthesis, Steven Harold Jury

Doctoral Dissertations

Temperature has a pervasive influence on lobster behavior, physiology and ecology and affects their subsequent distribution in thermally variable habitats such as estuaries and coastal areas. A multidisciplinary approach, including field and laboratory studies, was used to show: (1) that lobsters sense temperature with warm and cool thresholds as small as 0.1--0.2°C; (2) the relationship between temperature and activity is not linear, but instead switches between a high activity level in warmer months (10--20°C) and a lower level in colder months (<10°C) with transition periods in the spring and fall; (3) Parallel studies in the lab and field show that daily levels of activity are not greatly influenced by small temperature variations (i.e. tidally induced changes of 14°C), but activity levels are significantly higher in the field (249 +/- 55.1 m/d) than in the laboratory (88 +/- 12.0 m/d); (4) lobsters prefer a narrow range of temperatures over others available in a thermal gradient and avoid temperatures >23.5 +/- 0.4°C, suggesting that they behaviorally thermoregulate. While this preferred temperature shifts seasonally, the final preferred temperature …

The Role Of Cytokines In The Pathogenesis Of Experimental Legionella Pneumophila Infections, Corinna Mary Krinos

Doctoral Dissertations

Legionnaires' disease is an acute lobar pneumonia caused, primarily by the facultative intracellular pathogen Legionella pneumophila. This organism when inhaled by humans descends into the lower respiratory tract and parasitizes alveolar macrophages. L. pneumophila adhered to U-937 cells, A549 cells and peritoneal macrophages from A/J mice in an opsonin-independent fashion. Following attachment, the organism penetrated the cell membrane, replicated within these cells eventually inducing lysis. To better define the adhesion of L. pneumophila to host cells, an E. coli clone (LP 116), expressing the 25 kDa major outer membrane protein (MOMP) of L. pneumophila was used in binding studies. This …

Viability And Spatial Assessment Of Ecological Communities In The Northern Appalachian Ecoregion, Mark Gustav Anderson

Doctoral Dissertations

My objective was to design a conservation reserve system that included multiple viable examples of all ecological community types within one specific ecoregion---the Northern Appalachians. I developed and defined the boundaries of the ecoregion, constructed a comprehensive list of the ecological communities and determined their scale of occurrence and distribution patterns. I also assessed the types and distributions of biophysical features within the ecoregion and developed a hierarchical scheme to partition the region into biophysical subregions. Subsequently, I assessed 1500 occurrences of ecological communities in the region compiled from state Natural Heritage databases and an analysis of roadless areas. Each …

The Mut-2 Mutator Of Caenorhabditis Elegans, Kathrine Queta Flint Boese

Doctoral Dissertations

The mut-2 mutator plays multiple regulatory roles in the germ line of C. elegans. In addition to regulating germ line transposition of at least four distinct transposon families (Tc1, Tc3, Tc4 and Tc5) mut-2 is implicated in chromosome segregation. Animals that harbor the mut-2 mutator produce broods with a higher incidence of males phenotype (Him) as a result of an increase in X chromosome non-disjunction during meiosis.

Using the Him phenotype conferred by mut-2(r459), I mapped the gene to the dpy-14 sem-4 interval on LGI. However, efforts to identify a molecular clone of the gene were hampered because the available …

The Development Of Rna Probe And Rt-Pcr Assays For The Detection Of Enteroviruses In Sludge, Amy Elisabeth Moore

Doctoral Dissertations

Many wastewater treatment plants generate more sludge than can be disposed of by conventional means. The United States Environmental Protection Agency (USEPA) has encouraged communities to dispose of sludge by land application. Sludge may contain enteric viruses that are known to survive for long periods of time in sludge-amended soil and can travel great distances, potentially contaminating surface and ground water.

Standard cell culture methods for the detection of enteric viruses are costly and results are not obtained for 30 or more days. The development of methods that provide results more quickly and with lower cost are needed.

A 32P …

Controls On Spatial And Temporal Variability In Nitrous Oxide Fluxes Across A Tropical Rainforest Ecosystem In The Luquillo Experimental Forest, Puerto Rico, Claire Patricia Mcswiney

Doctoral Dissertations

Nitrous oxide (N2O) is a trace gas that contributes to the greenhouse effect and participates in the reactions that destroy stratospheric ozone. Soil microbial processes are significant producers of this trace gas, particularly in tropical areas, which are considered major sources in the global N2O budget. Nitrous oxide fluxes to the atmosphere are variable in space and time. In this study, spatial and temporal variability in surface N2O fluxes were assessed as well as the major environmental controls on N2O production for a tropical rainforest watershed in northeastern Puerto Rico. A static chamber technique was used to assess surface fluxes …

Characterization Of A Simian Hemorrhagic Fever Virus Large Envelope Glycoprotein Gene And Its Product., Xiaochun Wang

LSU Historical Dissertations and Theses

The goal of this project was to determine the genome organization, replication strategy and identification of the large envelope glycoprotein (GL) gene of simian hemorrhagic fever virus (SHFV). This virus is the fourth member of the new virus family Arteriviridae. The 3' end of the RNA genome from the prototype isolate of SHFV was cloned and sequenced. This 6,314 nucleotide (nt) sequence consisted of nine complete overlapping open reading frame (ORFs 2, 2a, 3, 4, 5, 6, 7, 8, and 9). At the 5' end of this sequence is a partial ORF, ORF 1b, and the 3' end is a …

Effects Of Low-Oxygen Atmosphere On The Growth And Development Of Arabidopsis Thaliana (L.) Heynh., Katrina Maria Ramonell

LSU Historical Dissertations and Theses

Interest in the improvement of crop productivity through repression of photorespiration led to experimental growth of plants in low O2 and the surprising finding that reproduction is inhibited under these conditions. Using Arabidopsis thaliana (L.) Heynh. cv. Columbia, studies were undertaken to understand the mechanism behind oxygen control of plant development. The hypothesis that developmental changes observed in low O 2 are due to repression of the plant hormones ethylene and brassinolide (which require O2 for biosynthesis) was tested. Arabidopsis was grown for 35 days in Sun bags in one of five altered O 2 atmospheres (210, 160, 100, 50, …

Systematics Of The Common Garter Snake, Thamnophis Sirtalis., John Jeffrey Boundy

LSU Historical Dissertations and Theses

Character variation was examined in the snake Thamnophis sirtalis . Initially, 187 characters were examined on five populations (OTUs). Only 12% of the characters failed to show geographic variation by ANOVA. A reduced data set of 72 characters remained after eliminating those that were invariant and correlated. The reduced data set was analyzed for interpopulation variation between 37 OTUs, of T. sirtalis. Numbers of significantly differentiated characters between OTUs, determined by ANOVA, were used to generate a UPGMA tree. The tree placed Texas and Chihuahuan populations as sister groups to all other OTUs, and grouped OTUs from west of the …

Null Codon-Based Models Of Synonymous And Nonsynonymous Substitution From A Phylogenetic Perspective., David A. Mcclellan

LSU Historical Dissertations and Theses

This dissertation focuses on the relationship between codon composition and the molecular evolution of protein-coding DNA sequences. Chapter 1 emphasizes the role of codon structure in determining patterns of nucleotide substitution, as well as the influence codon composition has on the evolution of the structure and function of the protein. The overall purpose of Chapter 1 is to establish the need to study molecular evolution at the codon level. In Chapter 2, the codon-degeneracy model (CDM) of molecular evolution is constructed. This model considers codon structure in terms of patterns of nucleotide site degeneracy. It allows the prediction of patterns …

Epidemiology Of Anthrax In The Kruger National Park, South Africa: Genetic Diversity And Environment., Kimothy Lyn Smith

LSU Historical Dissertations and Theses

The Kruger National Park, (KNP), in the Republic of South Africa, provides a unique opportunity to investigate interesting and unresolved aspects of the epidemiology of the disease anthrax. Anthrax is a disease of primarily mammals caused by the Gram-positive, rod-shaped, spore-forming bacteria Bacillus anthracis. Beyond it's great historical significance anthrax is clearly important in the world today. From a rich legacy of empirical investigations and observations in the form of ecological and epidemiological studies conducted around the world this work endeavors to distill and extract the essence of what biotic and abiotic factors of environment might be causally associated with …

Spatial Modeling Of Coastal Landscapes: Methodological And Scientific Applications., Mary Louise White

LSU Historical Dissertations and Theses

A number of issues related to landscape scale ecological modeling of the wetlands of southern Louisiana are examined in this study. First, using geostatistical methods, a new contour map of the wetland habitats in the Terrebonne basin of southern Louisiana is constructed from data collected in 1994. This map is proposed as the best field verified habitat map of the Terrebonne basin and contains statistical confidence intervals associated with the habitat contours. Second, the problem of how to evaluate the success of a landscape model prediction is investigated. The multiple resolution goodness of fit parameter Ft(k) is evaluated in detail …

Phylogeography Of Two Loligo Squid (Cephalopoda: Myopsida) In The Gulf Of Mexico And The Northwestern Atlantic Ocean., Scott William Herke

LSU Historical Dissertations and Theses

Based on restriction fragment length polymorphisms (RFLP) in mitochondrial DNA, the population structures of two species of Loligo squid were analyzed in the context of the classic Gulf of Mexico-Atlantic Ocean phylogeographic pattern. A 709-bp fragment of the cytochrome c oxidase (subunit I) gene was amplified by PCR from 356 L. pealei and 431 L. plei. Between latitudes 25°N and 43°N, each species had three common (>5% frequency) haplotypes and many rare haplotypes. Sequence data from all haplotypes indicated that nucleotide divergence between the two species ranged from 13.7 to 15.0% (transition-transversion ratio of ∼1.5; two inferred amino acid …

Production Of Transgenic Eastern Oysters., John Terrell Buchanan

LSU Historical Dissertations and Theses

The eastern oyster, Crassostrea virginica, supports a valuable industry in the United States and Louisiana. In recent years this industry has been plagued by diseases, creating interest in the use of gene transfer to produce oysters capable of eliminating pathogens. The goal of this work was to develop techniques for laboratory research of eastern oysters, and for transfer of genes to oyster gametes, larvae, and adults. Cell culture provides an effective alternative to work in whole animals. Cell attachment and spreading on various culture substrates was improved, and poly-D-lysine was identified as a superior substrate. Toxicity of the antibiotic G418 …