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Articles 1 - 11 of 11
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Homologous Neurons And Their Locomotor Functions In Nudibranch Molluscs, James M. Newcomb
Homologous Neurons And Their Locomotor Functions In Nudibranch Molluscs, James M. Newcomb
Biology Dissertations
These studies compare neurotransmitter localization and the behavioral functions of homologous neurons in nudibranch molluscs to determine the types of changes that might underlie the evolution of species-specific behaviors. Serotonin (5-HT) immunohistochemistry in eleven nudibranch species indicated that certain groups of 5 HT-immunoreactive neurons, such as the Cerebral Serotonergic Posterior (CeSP) cluster, are present in all species. However, the locations and numbers of many other 5 HT-immunoreactive neurons were variable. Thus, particular parts of the serotonergic system have changed during the evolution of nudibranchs. To test whether the functions of homologous neurons are phylogenetically variable, comparisons were made in species …
Investigation Into The Mechanism(S) Which Permit The High-Rate, Degradation Of Pahs And Related Petroleum Hydrocarbons In Sequencing Batch Reactors By Attached Cells In A Controlled Mixed Bacterial Community., Emad Ibraheim Hussein
Biology Dissertations
A stable mixed culture, deposited as ATCC 55644, previously shown to degrade petroleum hydrocarbons at relatively high concentrations was used as the source of inoculum. This culture was grown in Stanier’s minimal media, either in the presence of different concentrations of naphthalene, nitrobenzene and toluene (NNT) or naphthalene and toluene (NT) as the sole source of C and/or N. Results showed that the majority of the strains isolated from the mixed culture were able to grow in the presence of NNT or NT. A total of 20 different isolates were isolated from the mixed culture. Individual isolates were grown in …
The Role Of Ecological Interactions In Polymicrobial Biofilms And Their Contribution To Multiple Antibiotic Resistance, Heather Adele O'Connell
The Role Of Ecological Interactions In Polymicrobial Biofilms And Their Contribution To Multiple Antibiotic Resistance, Heather Adele O'Connell
Biology Dissertations
The primary objectives of this research were to demonstrate that: 1.) antibiotic resistant bacteria can promote the survival of antibiotic sensitive organisms when grown simultaneously as biofilms in antibiotics, 2.) community-level multiple antibiotic resistance of polymicrobial consortia can lead to biofilm formation despite the presence of multiple antibiotics, and 3.) biofilms may benefit plasmid retention and heterologous protein production in the absence of selective pressure. Quantitative analyses of confocal data showed that ampicillin resistant organisms supported populations of ampicillin sensitive organisms in steady state ampicillin concentrations 13 times greater than that which would inhibit sensitive cells inoculated alone. The rate …
Steroid Sensitive Neurons And Male Rat Mating Behavior, Gloria Gradine Huddleston
Steroid Sensitive Neurons And Male Rat Mating Behavior, Gloria Gradine Huddleston
Biology Dissertations
Male rat mating is a suite of individual behaviors mediated by the actions of two metabolites of testosterone (T), dihydrotestosterone (DHT) and estradiol (E2), on the brain. Individually, neither metabolite fully maintains or restores mating in castrated males, but both combined are as effective as T. Two hormone-responsive areas of the brain, the medial preoptic area (MPO) and the medial amygdala (MEA), are crucial for mating. These studies ask: by what mechanism(s) does E2 act in the MPO and MEA? We blocked the conversion of T to E2 in the MEA of intact male rats and sexual behavior was not …
Functional Role Of Dead-Box P68 Rna Helicase In Gene Expression, Chunru Lin
Functional Role Of Dead-Box P68 Rna Helicase In Gene Expression, Chunru Lin
Biology Dissertations
How tumor cells migrate and metastasize from primary sites requires four major steps: invasion, intravasation, extravasation and proliferation from micrometastases to malignant tumor. The initiation of tumor cell invasion requires Epithelial-Mesenchymal Transition (EMT), by which tumor cells lose cell-cell interactions and gain the ability of migration. The gene expression profile during the EMT process has been extensively investigated to study the initiation of EMT. In our studies, we indicated that tyrosine phosphorylation of human p68 RNA helicase positively associated with the malignant status of tumor tissue or cells. Studying of this relationship revealed that p68 RNA helicase played a critical …
Identification And Functional Analysis Of Crustacean Serotonin Receptors., Nadja Spitzer
Identification And Functional Analysis Of Crustacean Serotonin Receptors., Nadja Spitzer
Biology Dissertations
Constantly changing environments force animals to adapt by cycling through multiple physiological states. Plasticity in sensory, motor, and modulatory neural circuits is an essential part of these adaptive processes. Invertebrates with their accessible, identifiable neurons are excellent models for investigating the molecular and cellular mechanisms underlying state-dependent neural plasticity, and provide insight into similar processes in more complex systems. These properties have allowed highly detailed characterization of several crustacean circuits with respect to their connectivities, cellular properties, responses to various inputs, and outputs. Serotonin (5-HT) is an important neuromodulator in virtually every animal species. 5-HT signals are mediated primarily by …
Chemosensory Responses In Azospirillum Brasilense, Bonnie Baggett Stephens
Chemosensory Responses In Azospirillum Brasilense, Bonnie Baggett Stephens
Biology Dissertations
The ability to swim and navigate the surrounding environment confers an advantage to motile bacteria, allowing the occupation of niches that are optimum for survival and growth. Bacteria are too small to sense their environment spatially, so they must sense the environment temporally by comparing the past and present environments and altering their motility accordingly. Chemotaxis systems coordinate flagellar motility responses with temporal sensing of the environment. Chemotaxis is proposed to be involved in plant root colonization by directing soil bacteria toward root exudates of various cereals, promoting growth. The nitrogen-fixing alpha-proteobacterium Azospirillum brasilense utilizes chemotaxis to navigate its environment …
Immunoglobulins And Immunoglobulin Fc Receptors In Nonhuman Primates Commonly Used In Biomedical Research, Kenneth Alton Rogers
Immunoglobulins And Immunoglobulin Fc Receptors In Nonhuman Primates Commonly Used In Biomedical Research, Kenneth Alton Rogers
Biology Dissertations
Antibodies neutralize and eliminate pathogens, malignancies, and toxins by acting either alone or in association with Fc receptors which, once engaged, activate the elimination mechanisms of phagocytic cells. Based on structural differences, antibodies are divided into functionally distinct classes (IgM, IgD, IgG, IgE and IgA). Structure-function relationships within these classes are not well characterized. In addition, animal models for the assessment of potential therapeutic strategies for the modulation of the interaction between antibodies and Fc receptors are not established. Nonhuman primates are widely used to model human diseases and, represent excellent in vivo systems for this assessment. Therefore, we have …
Social Status-Dependent Changes In Behavior And Neurogenesis In The Crayfish Procambarus Clarkii, Cha-Kyong Song
Social Status-Dependent Changes In Behavior And Neurogenesis In The Crayfish Procambarus Clarkii, Cha-Kyong Song
Biology Dissertations
Crayfish (Procambarus clarkii) form dominance hierarchies, which are patterns of repeated fights with expected outcomes of winner and loser. Establishment of hierarchies allows dominants the first access to limited resources over subordinates, and leads to behavioral and cellular changes corresponding to the social status. Here, the animals¡¯ responses to an unexpected unilateral touch, a non-social stimulus, were examined with respect to their social status and to their social context. Isolates oriented to the stimulus source with raised claws and elevated posture. Dominants also oriented to the stimulus both when tested alone and in the presence of a subordinate. Subordinates oriented …
The Role Of Autoinducer-2 In Escherichia Coli Biofilm Formation And The Discovery Of A Plant-Derived Quorum Sensing Inhibitor, Chen Niu
Biology Dissertations
The objectives of this work are: 1) to determine whether plant essential oil components influence the ability of Escherichia coli and several Pseudomonas species to form biofilms, and inhibit bacterial quorum sensing; 2) to understand the role of autoinducer-2 (AI-2) in biofilm formation by E. coli W3110. The biofilm formation assays determined that cinnamon, cassia and citronella oils differentially affected growth-normalized biofilm formation by E. coli. Cinnamaldehyde (CA) also inhibited the swimming motility of E. coli. Subinhibitory concentrations of CA were effective at inhibiting two types of acyl homoserine lactone (HSL) mediated quorum sensing (QS), and also AI-2 mediated QS. …
The Role Of The Sia And Siu Abc-Type Transporters In Iron Utilization And Virulence In Streptococcus Pyogenes, Griselle Enid Montanez
The Role Of The Sia And Siu Abc-Type Transporters In Iron Utilization And Virulence In Streptococcus Pyogenes, Griselle Enid Montanez
Biology Dissertations
A limited understanding of iron uptake mechanisms is available for Streptococcus pyogenes, a hemolytic human pathogen capable of using a variety of hemoproteins in addition to ferric and ferrous iron. This study characterizes the transporters of iron-complexes siuADBG (for streptococcal iron uptake) and siaABC (for streptococcal iron acquisition). These ABC-type transporters are encoded by iron regulated operons and their protein products are homologous to components of heme and siderophore transporters found in both Gram-positive and Gram-negative bacteria. Mutants of the membrane permeases siuG and siaB were constructed and characterized. Mutations in both transporters demonstrated growth reduction in comparison to the …