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Synthesis Of Novel Amino Acids With Incorporation Into Peptides And Synthesis Of Peptides With Novel Aggregation States., Scott Michael Cowell Jan 1996

Synthesis Of Novel Amino Acids With Incorporation Into Peptides And Synthesis Of Peptides With Novel Aggregation States., Scott Michael Cowell

LSU Historical Dissertations and Theses

Peptides exhibit properties based on the amino acids present in the peptide and structure the peptide assumes in its environment. For example, peptides have been shown to be antimicrobial when they are amphipathic and in an $\alpha$-helical shape. The mechanism for this antimicrobial activity is subject to dispute. One theory states that the peptides work by forming a "pore" through the cell membrane which causes a depolarization of the membrane and the cell lysis because of osmosis. Another theory states that the peptides merely compromise the integrity of the membrane by solubilizing the membrane. In order for the "pore" theory …

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Genetic Components Of (Co)Variance For Postweaning Growth, Carcass Composition And Meat Quality Traits Among Brahman-Influenced Beef Steers., D. H. Denny Crews Jr Jan 1996

Genetic Components Of (Co)Variance For Postweaning Growth, Carcass Composition And Meat Quality Traits Among Brahman-Influenced Beef Steers., D. H. Denny Crews Jr

LSU Historical Dissertations and Theses

A genetic analysis was conducted on preweaning and postweaning growth and carcass composition records from steers produced in two long-term crossbreeding studies. In phase I, Angus (A), Brahman (B), Brangus (BR), Charolais (C) and Hereford (H) sires produced straightbred, F$\sb1$, back-cross, three-breed cross and 2- and 3-breed rotational crossbred steers (N = 708) from 1960 to 1968. Straightbred, F$\sb1$, back-cross, three-breed cross and 2-, 3- and 4-breed rotational crossbred steers (N = 1530) were produced from 1970 to 1988 by A, B, C and H sires in phase II. Direct and maternal additive and non-additive genetic effect contrasts were obtained. …

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Analysis Of Host-Parasite Cospeciation: Effects Of Spatial And Temporal Scale., James W. Demastes Jan 1996

Analysis Of Host-Parasite Cospeciation: Effects Of Spatial And Temporal Scale., James W. Demastes

LSU Historical Dissertations and Theses

All species of pocket gophers (Geomyidae) are parasitized by at least one species of chewing louse (Trichodectidae), and recent genetic studies have demonstrated that a pattern of cospeciation exists between these hosts and parasites (Hafner and Nadler, 1988; Hafner et al., 1994). Little work has been done on this host-parasite system at lower taxonomic (intrageneric) levels. Although cospeciation is evident in a study of pocket gophers within the genus Geomys and their chewing lice (Geomydoecus), reticulate evolution and retention of ancestral lineages obscure the pattern (Chapter 2). One key to understanding how these patterns of cospeciation are produced and how …

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Foraging Behavior And Habitat Selection Of Insectivorous Migratory Songbirds At Gulf Coast Stopover Sites In Spring., Chao-Chieh Chen Jan 1996

Foraging Behavior And Habitat Selection Of Insectivorous Migratory Songbirds At Gulf Coast Stopover Sites In Spring., Chao-Chieh Chen

LSU Historical Dissertations and Theses

Abundance of some species of Nearctic-Neotropical migrants has been declining dramatically since 1970. Most literature about Neotropical migrants is from the breeding grounds, and some is from the wintering grounds; very little is from stopover sites. I studied foraging behavior and habitat selection of insectivorous migratory songbirds at three stopover sites along northern coast of the Gulf of Mexico during spring migrations of 1993-1995. Each migrant species had its unique combination of foraging behavior and habitat use during stopover. Migrants selected certain habitat strata and plant species and avoided others. The decrease of understory vegetation in the reduced plots had …

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Synthesis Of Phosphonate Derivatives And Phosphonate Peptide Analogues., Maria De Fatima Fernandez Jan 1996

Synthesis Of Phosphonate Derivatives And Phosphonate Peptide Analogues., Maria De Fatima Fernandez

LSU Historical Dissertations and Theses

A general method for the preparation of a wide variety of phosphonate derivatives, including phosphonamides, thiophosphonamides, thiosphonates, and dithiophosphonates, from reduced phosphorus intermediates has been developed. Esters (or thioesters) of H-phosphinates are converted to the highly reactive phosphonochloridites by non-oxidative activation with dichlorotriphenylphosphorane. The phosphonochloridites react readily with alcohols, amines and thiols and after in situ oxidation or sulfurization, phosphonate derivatives can be isolated in moderate to very good yields (47-85%). This method was used to synthesize a thiophosphonate dipeptide, Boc-Val-$\Psi$(P(S)(OtBu)O) Ala-OCH$\sb3$ (15b), two thiophosphonamide dipeptides, Boc-Val-$\Psi$ (P(S)(OtBu)NH) Gly-OCH$\rm\sb2CH\sb3$ (16b) and Fmoc-Aib-$\Psi$ (P(S)(OBn)NH) Gly-OCH$\rm\sb2CH\sb3$ (20), and two phosphonate dipeptides, Fmoc-Aib-$\Psi$ …

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Polymerase Chain Reaction (Pcr) Assay For The Detection And Differentiation Of The Virulent Strains Of Mycoplasma Mycoides Subspecies Mycoides "Small Colony" Type From The Vaccine T1 Strain In Purified Dna And In Field Samples From Africa., Abdullahi Sheikh Hassan Kalif Jan 1996

Polymerase Chain Reaction (Pcr) Assay For The Detection And Differentiation Of The Virulent Strains Of Mycoplasma Mycoides Subspecies Mycoides "Small Colony" Type From The Vaccine T1 Strain In Purified Dna And In Field Samples From Africa., Abdullahi Sheikh Hassan Kalif

LSU Historical Dissertations and Theses

Two primer sets were manufactured from the cytadhesin P1 gene of M. Pneumoniae in an attempt to amplify homologous sequences in M. mycoides subsp. mycoides "SC" Type in a search for a P1-like gene in the latter organism. The first primer set MP-2 amplifies a 488 bp fragment in M. pneumoniae. The second primer set MP-3 amplifies a 303 bp fragment bracketing the 13-amino acid binding domain in the same organism. Both primer sets amplified the expected fragments in all the virulent strains of M. mycoides subsp. mycoides "SC" type. The primer sets did not however amplify the expected fragments …

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Physical And Functional Characterization Of Long Terminal Repeat Of Equine Infectious Anemia Virus., Soo Ho Kim Jan 1996

Physical And Functional Characterization Of Long Terminal Repeat Of Equine Infectious Anemia Virus., Soo Ho Kim

LSU Historical Dissertations and Theses

The U3 region of long terminal repeat (LTR) of equine infectious anemia virus (EIAV) contains transcriptional regulatory elements. To identify the elements in prototype (P), fetal donkey dermal cell-adapted (A), and two variant (V) EIAV LTRs, DNase I footprinting, gel shift, and transient gene expression assays were performed. The assays used U937 monocytic cells which can be induced into macrophages by 12-O-tetradecanoylphorbol-13-acetate (TPA). For study of AP1 sites, c-Jun/AP1 was also used. Footprinting with nuclear extracts from TPA-induced and uninduced U937 cells localized methylated DNA-binding protein (MDBP), PEA2, AP1, PU.1, and CCAAT enhancer-binding protein (C/EBP) sites as common elements in …

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Chemical Effects On Microbial And Sensory Qualities Of Catfish In Planktonic And Dynamic Systems., Michael Adrain Land Jan 1996

Chemical Effects On Microbial And Sensory Qualities Of Catfish In Planktonic And Dynamic Systems., Michael Adrain Land

LSU Historical Dissertations and Theses

Listeria monocytogenes has the potential to be a serious pathogen for the compromised health segment of our population (immunocompromised, young, elderly and the pregnant). While the infectious dose is generally believed to be high 1.0 $\times$ 10$\sp6$, infectious dosages of 1.0 $\times$ 10$\sp3$ have been reported. Listeria monocytogenes poses a threat because of several factors: ubiquity in nature, isolation from fresh/salt waters, soil, ruminates and 17% of the human population. Listeria monocytogenes can colonize surfaces within 20 minutes, evade sanitizing, and is capable of growth from 37$\sp\circ$C to below refrigeration temperature. Fish and seafoods are high in water activity and …

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Control Of African Striga Species By Natural Products From Native Plants., Joseph Kipronoh Rugutt Jan 1996

Control Of African Striga Species By Natural Products From Native Plants., Joseph Kipronoh Rugutt

LSU Historical Dissertations and Theses

Obligate root-parasitic flowering plants of the genus Striga (family Scrophulariaceae) cause considerable yield reductions of various crops in tropical and semi-tropical countries. Mature Striga species (witchweeds) plants produce copious quantities of minute seeds which remain dormant in the soil for many years until exudates from roots of various host plants induce germination. Economically effective means of control of Striga species are not yet available for small-scale farmers in developing countries. In the present study data is presented which indicate that the two most effective Striga control measures are crop rotation and suicidal germination. For the first time we have analyzed …

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Impacts Of Fire And Vertebrate Herbivores On Plant Community Characteristics And Soil Processes In A Coastal Marsh Of Eastern Louisiana, United States Of America., Mark Alan Ford Jan 1996

Impacts Of Fire And Vertebrate Herbivores On Plant Community Characteristics And Soil Processes In A Coastal Marsh Of Eastern Louisiana, United States Of America., Mark Alan Ford

LSU Historical Dissertations and Theses

Both vertebrate herbivores and fire have long been known to have dramatic and important effects on wetlands. In the first part of this study, conducted in the Pearl River Basin coastal marshes of Louisiana, the interaction between the effects of mammalian herbivores, especially nutria and wild boar, and fire was examined in three marsh community types: those dominated by Sagittaria lancifolia, Panicum virgatum, or Spartina patens/Scirpus americanus. Overall, above-ground biomass was reduced by burning but increased by fencing. Richness only increased in plots that were both burned and fenced. In the three communities, only Scirpus americanus cover was enhanced by …

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Relationships Between Brain Biogenic Amines And Reproductive And Defense Behavior In Honey Bees (Apis Mellifera L.)., Jeffrey Wayne Harris Jan 1996

Relationships Between Brain Biogenic Amines And Reproductive And Defense Behavior In Honey Bees (Apis Mellifera L.)., Jeffrey Wayne Harris

LSU Historical Dissertations and Theses

This dissertation represents an attempt to relate behavioral states of worker honey bees to brain levels of biogenic amines. The first chapter describes the results of experiments which indicated that brain levels of octopamine, dopamine and serotonin were affected by factors including the degree of handling stress, worker age, season of sampling and the source colony from which the workers were sampled. These results helped shape the methods employed in the subsequent chapters. The second and third chapters relate changes in brain dopamine levels to worker honey bee ovarian development. In particular, chapter II showed that an increase in brain …

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Analysis Of The Influence Of Genotype On Cayenne Pepper Fruit-Receptacle Detachment., Kay P. Gersch Jan 1996

Analysis Of The Influence Of Genotype On Cayenne Pepper Fruit-Receptacle Detachment., Kay P. Gersch

LSU Historical Dissertations and Theses

Two genotypes of cayenne pepper, Capsicum annuum L., were identified that differ significantly in ease of fruit detachment. Both greenhouse and field-grown plants of these genotypes, Cajun 1-9027 and Cap-9004, were investigated for differences in cell type and organization at the fruit-receptacle junction. Scanning electron microscopy revealed that mature fruit of Cajun 1-9027, which did not separate, exhibited a distinct region of sclerified cells that extended from the periphery of the fruit into the receptacle for at least 15 cell layers. In contrast, mature fruit of the more readily detachable Cap-9004 had fewer sclerified cells at the region of detachment. …

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Floral Development And Systematics Of The Caesalpinieae (Leguminosae: Caesalpinioideae)., Katherine Ellen Kantz Jan 1996

Floral Development And Systematics Of The Caesalpinieae (Leguminosae: Caesalpinioideae)., Katherine Ellen Kantz

LSU Historical Dissertations and Theses

The floral development of representatives from some of the informal taxonomic groups of the Caesalpinieae was examined. The floral developmental data was then used in a phylogenetic analysis in combination with more traditional morphological characters, including floral, vegetative and fruit characters. The analysis of 53 taxa and 84 characters produced 1215 equally parsimonious trees of length 386 (CI =.317, RI =.585, RCI =.186). Based on this analysis Caesalpinia sensu lato is not monophyletic, since at least two of the other genera in the Caesalpinia group are nested within Caesalpinia sensu lato. Of the infrageneric groups within Caesalpinia sensu lato, the …

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Perennial Weed Control Programs In Succession Planted And Fallowed Sugarcane (Saccharum Spp.) Fields., Donnie Keith Miller Jan 1996

Perennial Weed Control Programs In Succession Planted And Fallowed Sugarcane (Saccharum Spp.) Fields., Donnie Keith Miller

LSU Historical Dissertations and Theses

Studies were conducted over two years to compare weed control programs in succession planted sugarcane and in fallowed sugarcane fields. Glyphosate combined with tillage during the summer fallow period was more effective in controlling bermudagrass than tillage alone. Bermudagrass ground cover 240 days after planting ranged from 7 to 47% when glyphosate plus tillage was followed by atrazine after planting and pendimethalin plus atrazine in February. Bermudagrass ground cover was no more than 5% with applications of terbacil after planting and metribuzin in February. Cane and sugar yields were equivalent for the herbicide/tillage treatments even though bermudagrass control differed. In …

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Conditioning The Auditory System With Continuous Versus Interrupted Noise Of Equal Acoustic Energy: Is Either Exposure More Protective?, Ruth Ann Skellett Jan 1996

Conditioning The Auditory System With Continuous Versus Interrupted Noise Of Equal Acoustic Energy: Is Either Exposure More Protective?, Ruth Ann Skellett

LSU Historical Dissertations and Theses

Prior exposure to moderate-level acoustic stimulation (conditioning) can reduce and/or prevent the deleterious effects of subsequent higher level exposures (Canlon et al., 1988; Campo et al., 1991). Both continuous and interrupted schedules of moderate-level noise have been used as conditioning exposures, and both schedules have been effective in providing protection against subsequent noise trauma. However, there is evidence to suggest that continuous noise exposures are more damaging to the cochlea than interrupted exposures of equal acoustic energy (Bohne et al., 1985, 1987), and moderate-level continuous and interrupted noise exposures differ in the pattern of auditory sensitivity change that they produce …

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Postexercise Hypotension (Peh) In The Dog: Possible Role Of Immune System Cytokines., Gerald Dwayne Thompson Jan 1996

Postexercise Hypotension (Peh) In The Dog: Possible Role Of Immune System Cytokines., Gerald Dwayne Thompson

LSU Historical Dissertations and Theses

This study investigated postexercise hypotension (PEH) in five normotensive dogs testing these hypotheses: (1) PEH is present in the dog model; (2) high intensity exercise of 85% HR$\rm\sb{max}$ as compared to moderate intensity exercise of 60% HR$\rm\sb{max}$ induces a greater PEH; and (3) IL-1 and its activation of PGE$\sb2$ are associated with PEH. In experiment I, it was found that 85% HR$\rm\sb{max}$ exercise decreased systolic blood pressure (SBP) and mean arterial blood pressure (MABP) at 30 and 60 minutes postexercise (p $<$ 0.05). Both IL-1 and PGE$\sb2$ increased immediately following intense exercise, although temporal patterns were dissimilar. During non-exercise infusion of ibuprofen or dexamethasone (experiment II), blood pressure was not affected, but ibuprofen led to an overall inhibition of PGE$\sb2$. However, dexamethasone infusion led to a significant increase in PGE$\sb2$ at 180 and 210 minutes postinfusion. In experiment IIIA, after intense exercise following ibuprofen or saline infusion, PGE$\sb2$ increased at 120 to 180 minutes postexercise. Similar results were noted after exercise during dexamethasone treatment (experiment IIIB). In experiment IIIA & B, neither ibuprofen nor dexamethasone significantly affected PEH, although non-significant reductions in PEH was observed in dexamethasone treated animals. However, PGE$\sb2$ significantly increased after exercise at time points when PEH was not observed. These data indicate that (1) the intensity of exercise may have an effect on PEH, (2) there is partial support for the involvement of IL-1 and PGE$\sb2$ in PEH due to their immediate increase after exercise although a direct relationship was not observed, and (3) IL-1 still remains a possible mechanism responsible for PEH because of trends for attenuated PEH and PGE$\sb2$ responses following dexamethasone treatment.

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A Numerical Modeling Study Of The Gulf Of Mexico Under Present And Past Environmental Conditions., Susan Elizabeth Welsh Jan 1996

A Numerical Modeling Study Of The Gulf Of Mexico Under Present And Past Environmental Conditions., Susan Elizabeth Welsh

LSU Historical Dissertations and Theses

The Gulf of Mexico is an ideal location for paleoceanographic study using a three-dimensional ocean circulation model because of the availability of data to verify the model for the present. A description of the Gulf of Mexico circulation during the last glacial maximum is beneficial in interpreting the distribution of glacial fauna and adds to the understanding of global climate change because the Gulf of Mexico is an important link in the circulation of the Atlantic Ocean. The Florida Current originates in the Gulf of Mexico and contributes warm, salty water to the Gulf Stream. The Gulf Stream influences the …

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A Physiological Study Of Common Carpetgrass (Axonopus Affinis) Subjected To Cultural And Environmental Stress., Edward Wayne Bush Jan 1996

A Physiological Study Of Common Carpetgrass (Axonopus Affinis) Subjected To Cultural And Environmental Stress., Edward Wayne Bush

LSU Historical Dissertations and Theses

Common carpetgrass (Axonopus affinis Chase) is a low maintenance stoloniferous grass widely distributed throughout the southern coastal plains of the United States. This study investigated seed germination enhancement, seedhead suppression, waterlogging tolerance, winter hardiness, and maintenance practices for common carpetgrass. Pre-soaking common carpetgrass and centipedegrass (Eremochloa ophiuroides (Munro.) Hack.) seed was beneficial at the 30C germination temperature. Priming seed in KNO$\sb3$ solutions significantly accelerated seed germination of both centipedegrass and carpetgrass at 30C, and increased total germination percentage of centipedegrass. At 20 and 25C, seed priming significantly improved mean time of germination for both grass species and total germination percentage …

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Biochemical And Biophysical Studies Of Wild-Type And Active-Site Mutants Of Human Adenosine Deaminase., Qing Zeng Jan 1996

Biochemical And Biophysical Studies Of Wild-Type And Active-Site Mutants Of Human Adenosine Deaminase., Qing Zeng

LSU Historical Dissertations and Theses

The focus of this work is structural and functional studies of wild-type and active-site mutants of human adenosine deaminase. Two active-site amino acids, Glu217 and His238, were previously substituted with alanine by site-directed mutagenesis. The Glu217Ala and His238Ala mutants showed little or no changes in Zn content and $\rm K\sb{m}$ value, yet dramatic loss of enzyme activity. Circular dichroism studies of the solution conformation of wild-type and mutant human adenosine deaminases indicate that 30 to 50% of $\alpha$-helical structure is lost in Glu217Ala and His238Ala, respectively, whereas $\beta$-sheet structure is fully retained. Inhibitor binding is measured by a fluorescent assay. …

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Mechanism Of Nitrogen Fixation: Use Of Carbon Monoxide To Probe Nitrogenase Activity., Linda Margaret Cameron Jan 1996

Mechanism Of Nitrogen Fixation: Use Of Carbon Monoxide To Probe Nitrogenase Activity., Linda Margaret Cameron

LSU Historical Dissertations and Theses

The inhibitor CO was used to investigate the mechanism of Mo and V nitrogenase. While low pressures of CO enhanced, high pressures inhibited V nitrogenase-catalyzed C$\rm\sb2H\sb6$ formation. This is not the case for $\rm C\sb2H\sb4$ formation, where the rate of electron flux determined if CO acted as an enhancer or inhibitor. A two-site model is proposed, in which CO binding to one site enhances, and CO binding to both sites inhibits product formation. Replacement of CO(g) by Ar or $\rm C\sb2H\sb2$ resulted in correlated decay of hi-CO and development of lo-CO EPR signals, suggesting that the two signals arise from …

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Low Carbon Dioxide-Inducible Genes And Proteins In Chlamydomonas Reinhardtii., Zhi-Yuan Chen Jan 1996

Low Carbon Dioxide-Inducible Genes And Proteins In Chlamydomonas Reinhardtii., Zhi-Yuan Chen

LSU Historical Dissertations and Theses

At low CO$\sb2$ conditions, C. reinhardtii, like many other green algae, induces a CO$\sb2$ Concentrating Mechanism (CCM) to raise the internal Ci concentration. During the induction, at least five new polypeptides and six different genes are upregulated and some of the corresponding mRNAs or proteins are absent in high CO$\sb2$ requiring mutants. However the identities and functions of these genes are unknown. In this dissertation, I partially characterized four low CO$\sb2$ inducible genes and one low CO$\sb2$ inducible protein LIP-36. The complete cDNA sequences of clones 11I3 and 2I5 are 1311 bp and 985 bp, respectively. Neither of these two …

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Plant Species Diversity And Community Structure In A Louisiana Coastal Marsh., Laura Gough Jan 1996

Plant Species Diversity And Community Structure In A Louisiana Coastal Marsh., Laura Gough

LSU Historical Dissertations and Theses

The factors that control plant species diversity have been examined by many researchers, but with little consensus as to the causes of diversity patterns. Plant diversity has been correlated with disturbance, competition, soil resources, and other variables. In the research presented here, I investigated the relationship between plant species richness and biomass, competition, nutrient enrichment, flooding, salinity, and herbivory in field studies in Louisiana coastal marshes. Biomass alone was a poor predictor of richness in two Louisiana marshes. When environmental variables (flooding, salinity, and soil fertility) were included with biomass in a multiple regression model, 82% of the variance in …

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Fluorescence Studies Of Ecori Restriction Endonuclease Structure And Dynamics., Wei Liu Jan 1996

Fluorescence Studies Of Ecori Restriction Endonuclease Structure And Dynamics., Wei Liu

LSU Historical Dissertations and Theses

Sequence specific protein-DNA interaction involves changes in protein conformation and dynamics. Research work involved in this thesis is the study of structure and dynamics of EcoRI restriction endonuclease N-termini. The N-termini of EcoRI endonuclease has been shown to be essential for DNA cleavage and also stabilize EcoRI-DNA complex. But they are not resolved in the X-ray crystal structure. An Asn3Cys mutation was made at the N-termini by site-directed mutagenesis and the mutant was subjected to cysteine crosslinking, pyrene labeling and fluorescence studies. Chemical crosslinking of Asn3Cys mutant and steady-state fluorescence studies of pyrene-labeled mutant indicated that the N-termini are in …

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Toxicity Of Polycyclic Aromatic Hydrocarbons To Benthic Invertebrates., Guilherme R. Lotufo Jan 1996

Toxicity Of Polycyclic Aromatic Hydrocarbons To Benthic Invertebrates., Guilherme R. Lotufo

LSU Historical Dissertations and Theses

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants in aquatic environments. Because of their hydrophobicity, PAHs accumulate in bed sediments and pose a risk to the benthos. Information on the toxicity of sediment-associated PAHs is, however, limited and more information is needed to improve sediment quality-criteria and ecological-risk assessments. My research focused on improving our current knowledge of the acute and, especially, the sublethal effects of sediment-associated PAHs to aquatic invertebrates. Representatives of two phylogenetically distinct benthic invertebrate groups, freshwater tubificid oligochaetes and estuarine meiobenthic harpacticoid copepods, were used. Organisms were exposed to a range of concentrations of sediment-amended contaminants in …

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Immunocytochemical Localization Of Gonadotropins, Growth Hormone, And Prolactin In Equine Pituitary., Mohammad Saeed Rahmanian Jan 1996

Immunocytochemical Localization Of Gonadotropins, Growth Hormone, And Prolactin In Equine Pituitary., Mohammad Saeed Rahmanian

LSU Historical Dissertations and Theses

The present research was performed to characterize immunoreactive (ir) pituitary cells in the equine species. Two experiments were performed to measure the prevalence of single- and double-hormone labeled gonadotropes, lactotropes, somatotropes, and mammosomatotropes. In Experiments 1 and 2, pituitaries from three intact pony mares were processed for ultrastructural evaluation of cells stained for luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (PRL), and growth hormone (GH). Primary antibodies and gold-conjugated antibodies were used to double-stain ir-cells. The percentages of pituitary cells stained for each hormone in intact mares were: total gonadotropes, 15 to 32%; LH-only, 2 to 16%; FSH-only, 1 to …

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The Effect Of Silvicultural Treatments On Certain Mechanical And Physical Properties Of Loblolly Pine Wood Composites., Todd Finley Shupe Jan 1996

The Effect Of Silvicultural Treatments On Certain Mechanical And Physical Properties Of Loblolly Pine Wood Composites., Todd Finley Shupe

LSU Historical Dissertations and Theses

The effects of silvicultural treatments on mechanical and physical properties of loblolly pine (Pinus taeda L.) wood composites, veneer tensile and bending properties, and basic chemical properties were investigated. Stands managed in a plantation setting showed higher extractive contents. Holocellulose and alpha-cellulose were minimally affected by the silvicultural strategies. Klason lignin showed an inverse relationship with holocellulose. The effect of wood type was significant for the extractives because the innerwood region yielded much greater values than the outerwood. Holocellulose and alpha-cellulose increased in concentration from innerwood to outerwood. Veneer tensile strength was significantly affected by silvicultural practice, but other mechanical …

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Use Of Geographic Information System Technology To Assess Vulnerability To Shallow Groundwater Contamination., Brenda G. Bruner Jan 1996

Use Of Geographic Information System Technology To Assess Vulnerability To Shallow Groundwater Contamination., Brenda G. Bruner

LSU Historical Dissertations and Theses

Geographic Information System (GIS) technology was used to develop a local scale screening procedure for assessing shallow ground water's vulnerability to nitrate contamination. The procedure was based on the spatial distribution of ten key physical and chemical properties of soils. Both flow characteristics and attenuation capabilities of soils were incorporated into the assessment. Land surface areas were classified by the GIS to show the level of vulnerability present at a site as a result of existing natural conditions. The procedure produced a Vulnerability Index (VI), and resulted in VI ranging from 4.98 to 6.72 for the study area (with ten …

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Factors Controlling The Impacts Of South Louisiana Crude Oil On The Vegetation And Revegetation Of Coastal Wetlands., Qianxin Lin Jan 1996

Factors Controlling The Impacts Of South Louisiana Crude Oil On The Vegetation And Revegetation Of Coastal Wetlands., Qianxin Lin

LSU Historical Dissertations and Theses

The impacts of south Louisiana crude oil on three types of marsh, salt, brackish, and freshwater, dominated by Spartina alterniflora, S. patens, and Sagittaria lancifolia, respectively, were studied in the greenhouse. The influence of a number of factors such as marsh type, plant species, oil dosage, oil coverage, soil composition, leaf surface structure, season and meteorological conditions, on the impact of crude oil to marsh vegetation and revegetation were investigated. Vegetative sensitivity to south Louisiana crude oil increased in the order of S. lancifolia, S. alterniflora, and S. patens. Photosynthetic rates, stem densities, and the regrowth of aboveground biomass for …

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Synthesis, Molecular Characterization And Physical Behavior Of Novel Polymers And Polymer Blends: Poly(Aryl Ether)Sulfones, Labeled Poly(Gamma-Stearyl-Alpha, L-Glutamate) And Poly(Gamma-Stearyl-Alpha, L-Glutamate)/Polyethylene Blends., Frederick Harald Roos Jan 1996

Synthesis, Molecular Characterization And Physical Behavior Of Novel Polymers And Polymer Blends: Poly(Aryl Ether)Sulfones, Labeled Poly(Gamma-Stearyl-Alpha, L-Glutamate) And Poly(Gamma-Stearyl-Alpha, L-Glutamate)/Polyethylene Blends., Frederick Harald Roos

LSU Historical Dissertations and Theses

The structures of a number of novel poly(aryl ether) sulfones (nitro, aminomethyl, methyl and ethyl derivatives), which have applications as separation membranes, were determined unequivocally for the first time by applying sophisticated two-dimensional nuclear magnetic resonance (NMR) methods. The degree of substitution (DS) was found to vary among the products from 0.1 percent to about 2 percent (DS: nitro, 2.0; amino, 0.11; aminomethyl, 0.76; methyl, 2.12; ethyl, 2.05). Poly($\gamma$-stearyl-$\alpha$,L-glutamate), PSLG, is a "fuzzy rod" polymer composed of a central backbone that can exist as an $\alpha$-helix. This backbone, a polypeptide, is hydrophilic. The stearyl side chains (the "fuzzy" part of …

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Characterization Of Ionizing Radiation Sensitive (Irs) Mutants Of Deinococcus Radiodurans R1., Kumaraswamy S. Udupa Jan 1996

Characterization Of Ionizing Radiation Sensitive (Irs) Mutants Of Deinococcus Radiodurans R1., Kumaraswamy S. Udupa

LSU Historical Dissertations and Theses

Deinococcus radiodurans is extremely resistant to ionizing radiation and can withstand 5 kGy $\gamma$ radiation without loss of viability or evidence of mutation. Available evidence argues that an efficient DNA repair mechanism is responsible for the resistance these organisms possess to ionizing radiation. The enzymes which coordinate DNA repair in D. radiodurans are poorly characterized. Two new loci have been detected in D. radiodurans, namely, irrB and irrI which provide resistance. Mutational inactivation of either locus resulted in a partial loss of resistance to ionizing radiation. The extent of sensitivity was locus specific and differentially affected by inactivation of the …

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