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1
Erickson, Cynthia Ann. "Brain and behavior: Searching for the biological basis of learning." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186534.
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The hippocampus is a brain structure known to be important for learning and memory, more specifically for the acquisition of spatial information. Hebb (1940) suggested that storage of information in the brain may involve modifications in the strength of synaptic connections. One example of an artificially-induced synaptic alteration that may share common mechanisms with memory formation is long-term synaptic enhancement (LTE). Recently, behaviorally-induced changes in hippocampal synapses have been discovered to occur in conjunction with exploratory behavior. This type of change has been called short-term exploratory modulation (STEM). It was proposed that STEM could share common mechanisms with artificially-induced LTE and memory formation in the hippocampus. The primary goals in this dissertation were to determine the relationship between STEM and LTE, to identify the mechanisms controlling these changes, and to determine whether STEM was a critical component of memory storage, a memory modulator, or an epiphenomenon. Synaptic changes in the hippocampus were measured by recording perforant-path evoked field potentials in the fascia dentata from awake behaving rats during rest and exploration or under sodium pentobarbital anesthesia. In the first experiment, a positive correlation was found between learning in the Morris swim task and STEM in young and aged rats. Comparisons of LTE and STEM indicated that STEM did not reflect the same type of synaptic change observed in LTE, such that the two phenomena did not interact with each other. Furthermore, the nature of the changes in the evoked potentials were observed to be different. Another feature that distinguishes STEM from LTE is that the induction of LTE is dependent on the NMDA receptor, whereas STEM is NMDA-receptor independent. When rats were anesthetized and their bodies warmed passively, they exhibited STEM-like changes which were highly correlated with body temperature. These temperature-induced changes in evoked potentials had little impact on the functional output of cells in the fascia dentata. It is therefore concluded that exploration-induced changes in the hippocampus are largely due to brain temperature changes and have minimal impact on the functioning of neurons as originally proposed.
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Beteta, Pacheco Edmundo. "The psychophisiology and the development of clinic psychology." Pontificia Universidad Católica del Perú, 2013. http://repositorio.pucp.edu.pe/index/handle/123456789/99911.
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Up to date anatomical and biochemistry studies related to Brain mechanisms of behavior are reviewed. This type of research shold be work up in clinical psychology related to prevention, diagnostic and therapy of behavior disorders. In this way, the clinical psychology should make clinical research at differents age groups of the population. He will be able to study epidemiological risk factors together with neuropsychologycal tests and Brain imagind studies.Se presentan los avances en Psicofisiología, destacando los estudios anatómicos y bioquímicos de los mecanismos cerebrales que intervienen en la conducta. Estas investigaciones permiten ampliar el campo de la Psicología Clínica, tanto en la prevención como en el diagnóstico y terapéutica de los desórdenes de la conducta. En este objetivo, el psicólogo clínico podrá realizar estudios de investigación en la comunidad con la metodología de correlacionar factores de riesgo epidemiológicos, tests neuropsicológicos y estudios por imágenes.
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Sugarman, Franz. "The biological basis of schizophrenia /." Online version of thesis, 1991. http://hdl.handle.net/1850/11644.
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Wickett, John C. "The biological basis of general intelligence." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ28528.pdf.
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Brookner, Carrie Kazinoff. "Biological basis of cervical tissue autofluorescence /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Camfield, David Alan. "The biological basis of openness to experience." Swinburne Research Bank, 2008. http://hdl.handle.net/1959.3/49815.
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Thesis (PhD) - Swinburne University of Technology, Brain Sciences Institute, 2008.[A thesis submitted for the degree of] Doctor of Philosophy, Brain Sciences Institute, Swinburne University of Technology - 2008. Typescript. Includes bibliographical references (p. 250-272) and index.
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Jokisch, Daniel. "The neuropsychological basis of perception of biological motion." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=97349638X.
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Magi, Ross. "Dynamic behavior of biological membranes." Thesis, The University of Utah, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3680576.
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Biological membranes are important structural units in the cell. Composed of a lipid bilayer with embedded proteins, most exploration of membranes has focused on the proteins. While proteins play a vital role in membrane function, the lipids themselves can behave in dynamic ways which affect membrane structure and function. Furthermore, the dynamic behavior of the lipids can affect and be affected by membrane geometry. A novel fluid membrane model is developed in which two different types of lipids flow in a deforming membrane, modelled as a two-dimensional Riemannian manifold that resists bending. The two lipids behave like viscous Newtonian fluids whose motion is determined by realistic physical forces. By examining the stability of various shapes, it is shown that instability may result if the two lipids forming the membrane possess biophysical qualities, which cause them to respond differently to membrane curvature. By means of numerical simulation of a simplified model, it is shown that this instability results in curvature induced phase separation. Applying the simplified model to the Golgi apparatus, it is hypothesized that curvature induced phase separation may occur in a Golgi cisterna, aiding in the process of protein sorting.
In addition to flowing tangentially in the membrane, lipids also flip back and forth between the two leaflets in the bilayer. While traditionally assumed to occur very slowly, recent experiments have indicated that lipid flip-flop may occur rapidly. Two models are developed that explore the effect of rapid flip-flop on membrane geometry and the effect of a pH gradient on the distribution of charged lipids in the leaflets of the bilayer. By means of a stochastic model, it is shown that even the rapid flip-flop rates observed are unlikely to be significant inducers of membrane curvature. By means of a nonlinear Poisson- Boltzmann model, it is shown that pH gradients are unlikely to be significant inducers of bilayer asymmetry under physiological conditions.
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Chung, Ying-Hua. "Water behavior in different biological environments." Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/1213.
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In this thesis, we report on our studies of water dynamics and structure in various biological environments which include: the surfaces of proteins and various oligosaccharides, the intervening space between proteins; and in the vicinity of cryoprotectant disaccharides in the liquid and ice phases. From a theoretical perspective, we propose methodology to compute diffusivity and residence times on the surface of biomolecules. In particular our proposed algorithm to compute residence times appears to be better in dealing with poor statistics associated with the number of water molecules that remain on a surfaces for extended times. The type of linkage between monomers and the anomeric configuration all play a major role in determining the structure and dynamics of water on the surface of carbohydrates.
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Alhaj-Hussein, Baraa Tajuddin. "Investigating the biological and genetic basis in 'Helicobacter pylori' biofilm formation." Thesis, London School of Hygiene and Tropical Medicine (University of London), 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558365.
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Bashir, Amreen. "Exploring the biological basis for Salmonella persistence in food manufacturing environments." Thesis, Aston University, 2016. http://publications.aston.ac.uk/28847/.
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The persistence of Salmonella spp. in low moisture foods is a challenge for the food industry as despite control strategies already in place, notable outbreaks still occur. The aim of this study was to characterise isolates of Salmonella, known to be persistent in the food manufacturing environment, by comparing their microbiological characteristics with a panel of matched clinical and veterinary isolates. The gross morphology of the challenge panel was phenotypically characterised in terms of cellular size, shape and motility. In all the parameters measured, the factory isolates were indistinguishable from the human, clinical and veterinary strains. Further detailed metabolic profiling was undertaken using the biolog Microbial ID system. Multivariate analysis of the metabolic microarray revealed differences in metabolism of the factory isolate of S.Montevideo, based on its upregulated ability to utilise glucose and the sugar alcohol groups. The remainder of the serotype-matched isolates were metabolically indistinguishable. Temperature and humidity are known to influence bacterial survival and through environmental monitoring experimental parameters were defined. The results revealed Salmonella survival on stainless steel was affected by environmental temperatures that may be experienced in a food processing environment; with higher survival rates (D25=35.4) at temperatures at 25°C and lower humidity levels of 15% RH, however a rapid decline in cell count (D10=3.4) with lower temperatures of 10°C and higher humidity of 70% RH. Several resident factories strains survived in higher numbers on stainless steel (D25=29.69) compared to serotype matched clinical and veterinary isolates (D25=22.98). Factory isolates of Salmonella did not show an enhanced growth rate in comparison to serotype matched solates grown in Luria broth, Nutrient broth and M9 minimal media indicating that as an independent factor, growth was unlikely to be a major factor driving Salmonella persistence. Using a live / dead stain coupled with fluorescence microscopy revealed that when no longer culturable, isolates of S.Schwarzengrund entered into a viable nonculturable state. The biofilm forming capacity of the panel was characterised and revealed that all were able to form biofilms. None of the factory isolates showed an enhanced capability to form biofilms in comparison to serotype-matched isolates. In disinfection studies, planktonic cells were more susceptible to disinfectants than cells in biofilm and all the disinfectants tested were successful in reducing bacterial load. Contact time was one of the most important factors for reducing bacterial populations in a biofilm. The genomes of eight strains were sequenced. At the nucleotide and amino acid level the food factory isolates were similar to those of isolates from other environments; no major genomic rearrangements were observed, supporting the conclusions of the phenotypic and metabolic analysis. In conclusion, having investigated a variety of morphological, biochemical and genomic factors, it is unlikely that the persistence of Salmonella in the food manufacturing environment is attributable to a single phenotypic, metabolic or genomic factor. Whilst a combination of microbiological factors may be involved it is also possible that strain persistence in the factory environment is a consequence of failure to apply established hygiene management principles.
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Gu, Chen Ph D. Massachusetts Institute of Technology. "The molecular basis for tumor growth suppression by tRNA methyltransferase 9-like (TRM9L)." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112512.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biological Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references.
The human tRNA methyltransferase 9-like (TRM9L) gene is a homolog of yeast Trm9 and human ALKBH8 and it has an important function in suppressing tumor growth in colorectal cancer. Loss of heterozygosity events on the Chromosome 8p22 loci, where TRM9L is located, are overrepresented in a wide variety of cancers, including prostate cancer, breast carcinoma, and hepatocellular carcinoma; downregulation of TRM9L expression is also observed in many different types of cancer. These findings implicate a general role potentially played by TRM9L in tumor suppression. A mechanistic understanding of TRM9L would have a broad impact in oncology. The broad objective of my thesis research is to connect mechanistically the biochemical function of TRM9L to its tumor suppressing activity. Of my special interest is TRM9L is regulated at the protein level. In this thesis, I demonstrated that TRM9L is a phosphoprotein, with phosphorylation dynamics at serines S214, S255, S279, S291, S306, and S380 correlated with protein-protein interactions and tumorigenicity. Phosphorylation levels were found to be modulated by stressors to which cells become resistant when TRM9L is silenced. For example, oxidative stress caused by hydrogen peroxide (H202) exposure increased phosphorylation on S255, S291, and S380, but phosphorylation was unchanged in response to ionizing radiation. Using chemical genetics approaches, I showed that phosphorylation of S380 is downstream of ribosomal protein S6 kinase (RSK), which is downstream of H202-activated extracellular signalregulated kinase (ERK). TRM9L mutations S214A, S255A and S380A significantly enhanced tumor growth, while S214A and S255A mutations also abolished a direct interaction between TRM9L and certain 14-3-3 isoforms. The results revealed a novel oxidative stress phosphosignaling regulatory mechanism underlying TRM9L's tumor suppressor behavior. I also demonstrated that TRM9L altered the ability of colorectal cancer cells to respond to stresses caused by reactive oxygen and nitrogen species. Results supported the idea that TRM9L reduces the cell's capacity to detoxify harmful reactive oxygen and nitrogen species and effectively makes them more toxic. Finally, my finding supported the notion that TRM9L expression downregulates the hypoxia-induced cell migration, presumably by controlling an aspect of epithelialmesenchymal transition (EMT).
by Chen Gu.
Ph. D.
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Burkhart, Jessica Cheri, Chelsea Takamatsu, Daniel Gray, and Carol A. Barnes. "Understanding the Biological Basis of Cognitive Aging: The Role of Inhibitory Interneurons." Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/578894.
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Previous studies reveal decreases in hippocampal interneuron cell densities during normal aging. However, considerable variation in results exists within the literature. Overall, interneuron populations show either decreases or conservation in cell numbers expressing calcium binding proteins parvalbumin (PV) and calbindin (CB), and neuropeptides somatostatin (SOM) and neuropeptite Y (NPY) in hippocampal subregions of CA1, CA3, dentate granule cell layer, and dentate hilus. Notably, only few of the past aging studies showed correlations in cell loss with behavioral impairments in aged animals. This issue was addressed in the present study using male, young and old Fischer 344 rats, that were behaviorally characterized on four tasks before immunohistochemical staining and cell type quantification. Rats performed the Morris Watermaze, W-Track Continuous Spatial Alternation Task, Spontaneous Object Recognition (SOR) task, and Temporal Object Recognition (TOR) task. The old rats showed age-related deficits only in hippocampal-dependent memory tasks. Immunofluorescent imaging revealed an increase in SOM-immunoreactive interneurons in the dentate granule cell layer, as well as an increase in NPY expression in the dentate hilus. All other regions in which neurons were quantified showed no changes in any of the selected interneuron types examined. Contrary to previous findings, we found no decreases in interneuron populations anywhere in the hippocampus.
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Cowling, Jenny Elizabeth. "Physiological basis for biological invasion : the terrestrial amphipod Arcitalitrus dorrieni Hunt 1925." Thesis, University of Sheffield, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247178.
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Alleman, Austin [Verfasser]. "Genetic basis of behavior in Temnothorax ants / Austin Alleman." Mainz : Universitätsbibliothek Mainz, 2018. http://d-nb.info/1173062327/34.
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Barcelo, Batllori Silvia Barcelo. "Synthesis of sulforaphane and inhibition of cytochrome P450 enzymes as a basis for antigenotoxicity." Thesis, Aston University, 1997. http://publications.aston.ac.uk/15677/.
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Sulforaphane was synthesised with an overall yield of 15%, essentially via 1-methylsulfinylphthalimidobutane, which was oxidised to the sulfoxide moiety. Sulforaphane was a competitive inhibitor of CYPO2E1 in acetone-induced Sprague-Dawley rat microsomes (Ki 37.9 4.5 M), as measured by the p-nitrophenol hydroxylase assay. Ethoxyresorufin deethylase activity (EROD), a measurement of CYP1A activity, was also inhibited by sulforaphane (100 M) but was not competitive, and a preincubation time-dependence was observed. In view of these results, the capacity of sulforaphane to inhibit N-nitrosodimethylamine (NDMA)-induced genotoxicity (CYP2E1-mediated) was studied using mouse liver activation systems. Sulforaphane (>0.8 M) inhibited the mutagenicity of NDMA (4.4 mg/plate) in Salmonella typhimurium strain TA100 after pre-incubation for 45 min with acetone-induced liver 9000 g supernatants from Balb/c mice. Unscheduled DNA synthesis induced by NDMA (33.5 M) in mouse hepatocytes was also reduced by sulforaphane in a concentration-dependent manner (0.064-20 M). Sulforaphane was not genotoxic itself in any of these systems and cytotoxic only at high concentrations (>0.5 mM and > 40 M respectively). The ability of sulforaphane to modulate the orthologous human enzymes was studied using a human epithelial liver cell line (THLE) expressing individual human CYP450 isoenzymes. Using the Comet assay (a measurement of DNA strand breakage under alkaline conditions), NDMA (0.01-1 g/ml) and IQ (0.1-10 g/ml) were used to produce strand breaks in T5-2E1 cells (expressing human CYP2E1) and T5-1A2 cells (expressing human CYP1A2) respectively, however no response was observed in T5-neo cells (without CYP450 cDNA transfection). Sulforaphane inhibited both NDMA and IQ-induced DNA strand breakage in a concentration-dependent manner (0.1-10 M). Inhibition of CYP2E1 and CYP1A by sulforaphane may contribute to its chemoprotective potential.
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Ellis, Richard John. "Basis for the biocontrol of Pythium by fluorescent pseudomonads." Thesis, University of Oxford, 1997. http://ora.ox.ac.uk/objects/uuid:980ebd0a-5cd5-4408-858e-55e184e8566a.
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The aim of this thesis was to gain an understanding of the molecular and ecological basis for the biological control of Pythium by fluorescent pseudomonads. A fluorescent pseudomonad biocontrol agent (BCA), Pseudomonas fluorescens 54/96, identified as a potential candidate for commercial development, was analysed together with transposon induced mutants in a variety of assays for anti-fungal activity (Chapter 2). It was revealed that 54/96 had a fungistatic effect generated by a number of different mechanisms, which included nutrient competition and antibiosis. The synecology of this organism with Pythium was then compared to a similar organism (P. fluorescens SBW25) demonstrating a similar degree of anti-fungal activity (Chapter 3). The similarity of the population dynamics of these two strains prompted an examination of the genetic basis for the anti-fungal activity of the second strain, with the intention of comparing with 54/96 (Chapter 4). Again this revealed a multifactorial mode of action of SBW25 against Pythium. Whilst some mutants with reduced anti-fungal activity were deficient in growth on seed exudate others were unaffected, but the mechanisms appeared to be different to those utilized by 54/96. The comparison of strains was expanded to a larger collection of pseudomonad BCAs which were contrasted by a number of phenotypic and genotypic methods (Chapter 5). Various markers were identified which showed commonality within the different classes of BCA, the most useful of which was cyclopropanated fatty acids. These may prove to be a useful marker when screening for new pseudomonad BCAs. It was concluded that a greater understanding of the molecular, physiological and ecological basis of anti-fungal activity of bacterial will lead to the development of biocontrol strategies with improved efficacy.
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Andorf, Sandra. "A systems biological approach towards the molecular basis of heterosis in Arabidopsis thaliana." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5117/.
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Heterosis is defined as the superiority in performance of heterozygous genotypes compared to their corresponding genetically different homozygous parents. This phenomenon is already known since the beginning of the last century and it has been widely used in plant breeding, but the underlying genetic and molecular mechanisms are not well understood.
In this work, a systems biological approach based on molecular network structures is proposed to contribute to the understanding of heterosis.
Hybrids are likely to contain additional regulatory possibilities compared to their homozygous parents and, therefore, they may be able to correctly respond to a higher number of environmental challenges, which leads to a higher adaptability and, thus, the heterosis phenomenon.
In the network hypothesis for heterosis, presented in this work, more regulatory interactions are expected in the molecular networks of the hybrids compared to the homozygous parents. Partial correlations were used to assess this difference in the global interaction structure of regulatory networks between the hybrids and the homozygous genotypes.
This network hypothesis for heterosis was tested on metabolite profiles as well as gene expression data of the two parental Arabidopsis thaliana accessions C24 and Col-0 and their reciprocal crosses. These plants are known to show a heterosis effect in their biomass phenotype. The hypothesis was confirmed for mid-parent and best-parent heterosis for either hybrid of our experimental metabolite as well as gene expression data. It was shown that this result is influenced by the used cutoffs during the analyses. Too strict filtering resulted in sets of metabolites and genes for which the network hypothesis for heterosis does not hold true for either hybrid regarding mid-parent as well as best-parent heterosis.
In an over-representation analysis, the genes that show the largest heterosis effects according to our network hypothesis were compared to genes of heterotic quantitative trait loci (QTL) regions. Separately for either hybrid regarding mid-parent as well as best-parent heterosis, a significantly larger overlap between the resulting gene lists of the two different approaches towards biomass heterosis was detected than expected by chance. This suggests that each heterotic QTL region contains many genes influencing biomass heterosis in the early development of Arabidopsis thaliana. Furthermore, this integrative analysis led to a confinement and an increased confidence in the group of candidate genes for biomass heterosis in Arabidopsis thaliana identified by both approaches.Als Heterosis-Effekt wird die Überlegenheit in einem oder mehreren Leistungsmerkmalen (z.B. Blattgröße von Pflanzen) von heterozygoten (mischerbigen) Nachkommen über deren unterschiedlich homozygoten (reinerbigen) Eltern bezeichnet. Dieses Phänomen ist schon seit Beginn des letzten Jahrhunderts bekannt und wird weit verbreitet in der Pflanzenzucht genutzt. Trotzdem sind die genetischen und molekularen Grundlagen von Heterosis noch weitestgehend unbekannt. Es wird angenommen, dass heterozygote Individuen mehr regulatorische Möglichkeiten aufweisen als ihre homozygoten Eltern und sie somit auf eine größere Anzahl an wechselnden Umweltbedingungen richtig reagieren können. Diese erhöhte Anpassungsfähigkeit führt zum Heterosis-Effekt. In dieser Arbeit wird ein systembiologischer Ansatz, basierend auf molekularen Netzwerkstrukturen verfolgt, um zu einem besseren Verständnis von Heterosis beizutragen. Dazu wird eine Netzwerkhypothese für Heterosis vorgestellt, die vorhersagt, dass die heterozygoten Individuen, die Heterosis zeigen, mehr regulatorische Interaktionen in ihren molekularen Netzwerken aufweisen als die homozygoten Eltern. Partielle Korrelationen wurden verwendet, um diesen Unterschied in den globalen Interaktionsstrukturen zwischen den Heterozygoten und ihren homozygoten Eltern zu untersuchen. Die Netzwerkhypothese wurde anhand von Metabolit- und Genexpressionsdaten der beiden homozygoten Arabidopsis thaliana Pflanzenlinien C24 und Col-0 und deren wechselseitigen Kreuzungen getestet. Arabidopsis thaliana Pflanzen sind bekannt dafür, dass sie einen Heterosis-Effekt im Bezug auf ihre Biomasse zeigen. Die heterozygoten Pflanzen weisen bei gleichem Alter eine höhere Biomasse auf als die homozygoten Pflanzen. Die Netzwerkhypothese für Heterosis konnte sowohl im Bezug auf mid-parent Heterosis (Unterschied in der Leistung des Heterozygoten im Vergleich zum Mittelwert der Eltern) als auch auf best-parent Heterosis (Unterschied in der Leistung des Heterozygoten im Vergleich zum Besseren der Eltern) für beide Kreuzungen für die Metabolit- und Genexpressionsdaten bestätigt werden. In einer Überrepräsentations-Analyse wurden die Gene, für die die größte Veränderung in der Anzahl der regulatorischen Interaktionen, an denen sie vermutlich beteiligt sind, festgestellt wurde, mit den Genen aus einer quantitativ genetischen (QTL) Analyse von Biomasse-Heterosis in Arabidopsis thaliana verglichen. Die ermittelten Gene aus beiden Studien zeigen eine größere Überschneidung als durch Zufall erwartet. Das deutet darauf hin, dass jede identifizierte QTL-Region viele Gene, die den Biomasse-Heterosis-Effekt in Arabidopsis thaliana beeinflussen, enthält. Die Gene, die in den Ergebnislisten beider Analyseverfahren überlappen, können mit größerer Zuversicht als Kandidatengene für Biomasse-Heterosis in Arabidopsis thaliana betrachtet werden als die Ergebnisse von nur einer Studie.
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Le, Yevgeniya. "Immunocamouflage : the biophysical and biological basis of immunoprotection by grafted methoxypoly(ethylene glycol)." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/20562.
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Development of novel approaches for the direct immunomodulation of allogeneic donor cells would have significant utility in tissue transplantation. Immunocamouflage of cell surfaces by covalently grafted methoxypoly(ethylene glycol) (mPEG; PEGylation) has emerged as a promising approach. While previous studies demonstrated the in vitro and in vivo efficacy of immunocamouflaged allogeneic cells and viruses, the biophysical mechanisms of immunoprotection have not been well-defined due to the labile nature of biological samples. To overcome this limitation, polystyrene latex particles (1.2 and 8.0 µm) were used to elucidate the biophysical mechanisms of immunocamouflage via the effects of the chemical and physical properties of the polymer, as well as the consequences of target size. These findings were correlated with the biological studies utilizing human red blood cells and lymphocytes. It was demonstrated that the two biophysical mechanisms were responsible for the immunocamouflage of PEGylated surfaces: 1) hydrodynamic shielding of surface charge; and 2) steric exclusion of macromolecules from the surface. Surface charge camouflage of latex particles and erythrocytes was best achieved with long polymer chains, regardless of the target size. However, inhibition of surface-macromolecule interactions indicated a target size dependence. The biophysical latex model demonstrated that short chain polymers (2 kDa) were more effective at preventing protein adsorption to small beads (1.2 µm), while long chain polymers (20 kDa) exhibited increased efficacy on large particles (8.0 µm). Consistent with the biophysical model, immunocamouflage of lymphocytes (~10 µm) was best achieved using long chain polymers as measured by: 1) inhibition of antigen-antibody binding (CD3, CD4 and CD28); and 2) allorecognition in a 2-way mixed lymphocyte reaction. The biological model also demonstrated that cell surface topography and antigen localization were critical in selecting the optimal polymer size. Importantly, PEGylation did not result in any cellular toxicity at immunoprotective levels that rendered modified surfaces more biocompatible. Thus, these studies delineated the biophysical mechanisms of immunocamouflage defined by the chemical and physical parameters of the polymer and influenced by target size and surface complexity. Cell or tissue specific optimization of these factors will be critical for the efficient immunocamouflage of allogeneic cells in transfusion and transplantation medicine.
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Stevenson, Leonard. "A molecular basis for the biological control activity of a pseudomonas fluorescens strain." Thesis, University of Bristol, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240424.
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Alvarez, Luis M. (Luis Manuel). "Modulating cell behavior with engineered HER-receptor ligands." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/62985.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, September 2009."August 2009." Cataloged from PDF version of thesis.
Includes bibliographical references.
The primary motivation for this work is the manipulation of EGFR family signaling to influence regenerative responses of mesenchymal stem cells (MSC). Underlying the potential of regenerative medicine is the need to understand and control cell behavior. A 'cue, signal, response' paradigm has emerged as a framework for building predictive models for manipulation of cells to achieve desired responses. The HER receptor tyrosine kinase (RTK) family is an attractive target for manipulation of cues and signals, as its four members - epidermal growth factor receptor (EGFR or HERI), HER2, HER3 and HER4 - influence processes as diverse as development, wound healing, migration, and tissue homeostasis and family members are expressed by almost every cell type. All HER receptors require either homodimerization or heterodimerization with other family members for activation of signaling pathways, and the various dimer pairs are not equivalent in their ability to activate all the downstream pathways. Hence, signaling (and phenotypic) outcomes may be dictated not only by the number (or fraction) of each type of receptor ligated, but by the quantitative distribution of these receptors into various possible dimer pairs. The canonical physiological ligands for the HER family receptors are monomeric, allowing occupied receptors to freely homodimerize or heterodimerize. The premise of this work is that engineered bivalent ligands can drive specific dimerization events to enhance or inhibit signaling by various HER family receptors in a quantitative fashion that might be predicted on the basis of receptor expression. This work focuses on the design and implementation of engineered protein systems that are targeted to control homo and heterodimerization of HERI and HER3. One broad consequence of using homodimer ligands is to quantitatively force ligand-occupied HERI or HER3 to homodimerize and thus inhibit heterodimerization. Homodimerization may reinforce preferred signaling pathways (e.g, HERI-HERI vs HER1-HER2) - with implications for tissue regeneration and inhibit undesirable pathways (e.g. HER2-HER3) - with implications in cancer. Preliminary results suggest that whereas the monomeric HER3 ligand activates canonical signaling pathways expected from HER3-HER2 interactions, dimeric ligands inhibit signaling, presumably by forcing homodimerization of the kinase-inactive HER3 receptors. This thesis focuses on developing the design principles to use bivalent ligand dimers to control signaling, experimental testing of the hypothesis that signaling pathways can be controlled by such ligands and are quantitatively different than those for monovalent ligands, and demonstration of how such ligands influence proliferation of human marrow stromal cells, a cell type important for bone regeneration. In addition, the issue of practical implementation in a tissue engineering setting is addressed by implementing approaches to tether bivalent ligands to scaffolds in a manner that preserves signaling function.
by Luis M. Alvarez.
Ph.D.
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Tesdahl, Natalya S. "Molecular basis of autism-like behavior in SAPAP3-deficient mice." Thesis, University of Iowa, 2017. https://ir.uiowa.edu/etd/5657.
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Autism Spectrum Disorders (ASDs) are a diverse group of diseases that share the common features of deficits in social communication and rigid, repetitive behavior patterns. Most genetic alterations related to ASD can be broadly split into two categories – those pertaining to mTOR/PI3K signaling, and those pertaining to synaptic connections and structure. While a number of synaptic scaffolding proteins have been linked to ASD via human genetic studies and mouse models, SAP90/PSD95 associated protein 3 (SAPAP3) has not. Loss of SAPAP3 in mice, however, results in compulsive grooming behavior, which parallels one of the core features of ASD. On a molecular level, loss of SAPAP3 results in increased signaling via the group I metabotropic glutamate receptor mGluR5. As mGluR5 is known to regulate protein transcription and translation, we conducted a proteomic comparison of sapap3-/- mice relative to sapap3+/+ mice. We identified a number of differentially regulated proteins, the majority of which were upregulated in sapap3-/- mice. Of those, we chose to further investigate collapsin response mediator protein 2 (CRMP2), due to its role in regulating dendritic branching and neurogenesis. We found abnormalities in both dendritic branching and postnatal neurogenesis in sapap3-/- mice, changes which may contribute to some of their behavioral phenotypes. We also found that ultrasonic vocalization, a form of communication for mice, is altered in neonatal sapap3-/- mice. Taken together, these findings provide new direction that could lead to future therapeutics for patients with ASD, as well as an early read-out of the effectiveness of any potential treatment.
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Smith, Arthur J. "Implementing Core Values in the High-Tech Industry." ScholarWorks, 2011. https://scholarworks.waldenu.edu/dissertations/853.
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Previous research has indicated that the path-goal theory is an effective way to study leadership behavior; however, a gap exists in the literature with respect to its achievement-oriented and participative leadership dimensions in high-tech organizations. In this quantitative study, the effects of a core values intervention on the four leadership dimensions of House's path-goal theory were evaluated at a semiconductor manufacturer with a focus on the differences between supervisors and non-supervisory personnel. Data were gathered from the validated, company-developed Corporate Culture Survey that was administered pre and post intervention. Data were also gathered from a categorization task that sorted the Corporate Culture Survey items into leadership dimensions to form the dependent measures. ANOVA was used to determine whether significant changes in perceptions of leadership behavior by supervisors and non-supervisory personnel occurred on House's four leadership dimensions as a result of the values intervention. Results of a two-way ANOVA on the directive supervision subscale show an interaction between the pre-post intervention factor and supervisors/non-supervisory factor in addition to a main effect for the pre-post intervention factor. Analysis of the simple effects for directive leadership shows a significant pre-post intervention gain on mean score for non-supervisory personnel. Implications for social change include recognizing perceptions of enhanced directive leadership that can help remove manufacturing interruptions to increase productivity and decrease costs.
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Lau, Johnny King Lam. "The neural basis of object perception : dissociating action and semantic processing." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6811/.
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This thesis has evaluated the roles of dorsal and ventral processing streams in recognition and use of objects. Four main empirical studies are presented. First, to investigate how the cortical brain processes semantic and action knowledge in different object-related tasks, I examined structural data from stroke patients (Chapter 2) and functional data from healthy individuals (Chapter 3) using a voxel-wise statistical analysis method. Using data of different modalities (structural CT, fMRI) from different sources (patients’ lesions; healthy subjects’ functional activity) handled with a systematic analysis approach, I attempted to find convergent evidence to support the dissociation of semantic and action processing. Second, I also looked into the potential differentiation within the mechanisms underlying object-related action (Chapter 4) and object naming (Chapter 5) separately. Overall, comparable findings were provided from the voxel-based morphometric analysis of patients’ lesion data and the fMRI study with healthy participants: an association was observed between ventral brain structures and the retrieval of semantic knowledge/object recognition while a dorsal fronto-parietal-occipital network was found to support the processing of action knowledge/object-oriented action. Specific dissociations were also observed within the representations for object-oriented actions as well as the mechanisms underlying naming of objects.
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Wijeyekoon, Ruwani Shamila. "The biological basis of heterogeneity in Parkinson's disease : insights from an innate immune perspective." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/283202.
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The biological basis of the clinical heterogeneity in Parkinson's Disease (PD) is unclear. It is likely to involve complex interactions between genetic and environmental factors and between a range of pathological processes, including protein homeostasis and immune system function. Microglial activation in the brain and peripheral innate immune changes are known to occur in PD. Recently genetic, animal and cellular studies have linked several innate immune related genes and proteins (e.g. HLADR, TREM2, TLR2, TLR4, caspase-1) to PD and provided evidence that they may have a role in PD pathogenesis. Alpha-synuclein is central to PD, with evidence from neuropathology, genetics and animal/cell models indicating that it plays a significant pathogenic role. There is developing evidence directly linking innate immune activity and alpha-synuclein pathology. For example, inflammation, particularly in response to microbial infection, is associated with increased alpha-synuclein accumulation in the periphery and activation of the innate immune inflammasome related caspase-1 leads to increased cleavage and aggregation of alpha-synuclein. Overall Hypothesis- "Parkinson's disease (PD) and its clinical heterogeneity are associated with systemic changes in innate immune and associated microbial factors and in alpha-synuclein". This was investigated from the perspective of an epidemiological study, a study of peripheral blood monocyte, innate immune/microbial markers and a cerebrospinal fluid (CSF) study in PD patients. *The epidemiological study, involved the longitudinal PICNICS cohort of 290 Idiopathic PD patients, and showed that the use of medication known to influence alpha-synuclein and immune function is associated with motor heterogeneity in PD. *The peripheral immune study involved 41 early PD patients and 41 age, gender and MAPT genotype matched paired controls, with the PD patients categorised into 2 groups based on the presence of previously identified clinical and genetic risk factors for the development of an early dementia (impaired semantic fluency, pentagon copying and MAPT H1/H1 haplotype). This study demonstrated that the phenotypic profile of peripheral monocytes and the level of serum alpha-synuclein and relevant innate immune and microbial markers do differ in early PD compared to controls and that there are differential changes in those patients at higher versus lower risk for early dementia. The systemic alpha-synuclein related changes appear to be present overall in PD patients compared to controls, while the more microbial/innate immune related changes appear to be more prominent in the dementia higher risk group. *The CSF study involved samples from 35 PD patients and has demonstrated evidence of relationships between neurodegeneration-linked CSF tau species and inflammatory cytokines, and between CSF alpha-synuclein and cognitive function, suggesting that these factors may be involved in PD heterogeneity within the central nervous system as well. Overall, these studies provide evidence that variations in alpha synuclein/ tau homeostasis and innate immune and microbial factors are related to PD and its clinical heterogeneity.
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Khan, Tahmina. "Investigation of the biological and chemical basis underpinning contact lens solution induced corneal staining." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/investigation-of-the-biological-and-chemical-basis-underpinning-contact-lens-solution-induced-corneal-staining(3d84a7c2-54d9-4c8f-92ad-4d4fa6134c07).html.
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Purpose: Sodium fluorescein ('fluorescein') is the most commonly used diagnostic ophthalmic dye for clinical assessment of the ocular surface. An increase in fluorescein staining presents after the use of certain multi-purpose solutions (MPS) and contact lenses, which is a clinical phenomenon known as solution induced corneal staining (SICS). The clinical relevance and mechanisms underpinning fluorescein staining however is conflicting in the literature. Currently a number of studies indicate fluorescein localises within cells that are healthy and metabolically active, in contrast to conventional thought that fluorescein staining of MPS treated cells is indicative of cellular toxicity; however the precise mechanism underpinning fluorescein internalisation is unknown. The aim of this doctoral thesis was thus to investigate novel biological mechanisms mediating fluorescein uptake and to determine the chemical inducers of increased fluorescein staining. Methods: Spectrofluorimetry was used to analyse the fluorescence intensity of various fluorescein solutions and of tear samples after fluorescein application to the ocular surface. For assessment of fluorescein uptake in cell cultures exposed to test MPS, fluorescence microscopy was performed; subsequently a high content analysis (HCA) microscopy methodology developed in this thesis, was used to enumerate fluorescein fluorescence intensity. The physiological state of cell cultures treated with a number of MPS and fluorescein were also assessed using propidium iodide (PI), Caspase-3 antibody for apoptosis analysis, metabolic activity assays and confocal microscopy. Endocytosis, macropinocytosis, and receptor-mediated uptake, mechanisms which previous to this work have not been investigated in association with SICS and fluorescein uptake, were studied using chemical inhibitors and serum starvation in cell culture, and then analysed by HCA. To study the hyperfluorescence inducing properties of MPS components, surfactant Tetronic 1107 (an MPS surfactant component typically overlooked and not investigated as an inducer of SICS) and Triton X-100 (a surfactant not found in MPS) were exposed to cell cultures and after fluorescein treatment, were analysed by HCA; metabolic activity assessment of identically treated cultures were also performed. Similarly, HCA and metabolic activity measurements were also performed in cell cultures treated with MPS biocides PHMB and Polyquaternium-1 (PQ-1). Results: Fluorescein fluorescence intensity was not affected by temperature, by alkali solvents, or by different MPS formulations; concentration remains the primary factor by which fluorescein intensity is affected. It was seen that after 1% w/v fluorescein instillation on the ocular surface, fluorescein concentration in tear samples significantly decreased within the first minute and decreased to as little as 0.0001% w/v after 10 minutes. Fluorescence microscopy and HCA techniques revealed that on treatment with Biotrue® (Bausch+Lomb, referred to as P-PQ1-1107) and ReNu Sensitive Multi-purpose Solution® (Bausch+Lomb, referred to as P-1107), fluorescein uptake increased in cell cultures, as typically seen clinically. Also typically seen clinically, cell cultures treated with Opti-free Replenish® (Alcon; PQ1-Aldox-1304) and Complete Revitalens® (AMO; PQ1-Alex-904) did not induce hyperfluorescence. Significantly, only those cells treated with PQ1-Aldox-1304 and PQ1-Alex-904 exhibited an increase in PI and loss of metabolic activity. Additionally, given that no significant Caspase-3 staining in all test MPS cells was seen by fluorescence microscopy and blebbing was only observed by confocal microscopy in P-PQ1-1107 treated cells, increased fluorescein hyperfluorescence is unlikely to be related to apoptosis. Study of various biological internalisation mechanisms revealed that dynamin (a protein associated with endocytosis) inhibition in P-PQ1-1107 or P-1107 treated cells significantly decreases fluorescein uptake with no detrimental effect to cell metabolic activity. Interestingly, on quantifying fluorescein uptake in surfactant treated cells, a significant increase in hyperfluorescence was measured with only Tetronic 1107 at concentration 1% w/v with no significant effect on cellular metabolic activity. In contrast, cell culture treatment with biocides PHMB, and PQ-1 did not induce increased fluorescein uptake comparable to MPS PPQ1-1107 or P-1107; metabolic activity assays revealed that this is likely attributed to the decrease in cell metabolic activity exhibited with these biocides. Conclusions: The differential fluorescein staining associated clinically with four varied MPS was also seen in an unique in vitro model, allowing the subsequent study of the SICS phenomenon and the fundamental basis of fluorescein uptake. Using this in vitro model, it was seen that fluorescein internalisation is associated with the protein dynamin in healthy, metabolically active cells, and is unlikely to be mediated by apoptosis. Moreover, fluorescein uptake is induced by surfactant Tetronic 1107 and not biocides PHMB or PQ-1, which is in contrast to the popular belief that increased hyperfluorescence is induced by the biocide component of MPS.
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Grano, Maldonado Mayra Ixchel. "The biological and behavioural basis of host selection in the transmission of Gyrodactylus (Monogenea)." Thesis, University of Stirling, 2010. http://hdl.handle.net/1893/3700.
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The ectoparasitic monogenean fluke, Gyrodactylus salaris, is a parasite known to be highly pathogenic to Atlantic salmon (Salmo salar). Although present in the environment of several neighbouring European countries, the UK is thought to be G. salaris-free, but, if national contingency plans to control this parasite are to be effective, it is vital that we understand the factors underlying its transmission from host to host. This study demonstrates that the majority of parasites transferring to new hosts are mature parasites that have reproduced at least once. Since, exploration and host transfer strategies pose a risk to survival; the parasite will endeavour to pass on its genes before attempting to transfer from one host to another. This study has also shown that when pregnant parasites are forced to leave their hosts, their offspring are aborted prematurely to ensure the survival of the mature parasite. Gyrodactylids do not possess a free-swimming stage in their life cycle, which allows for their migration between hosts. In spite of this, they are able to rapidly colonise naïve hosts, even in non-shoaling populations of fish. This study investigates the transmission strategies employed by detached parasites in the colonisation of new hosts. Observations of gyrodactylids collected from 3-spine sticklebacks, Gasterosteus acuelatus, suggest that their activity increases as a stickleback approaches, alerting the host to its presence. The parasite is then ingested directly by the prospective host. A time series of experimental exposures and specimens prepared for Scanning Electron Microscopy (SEM) suggest that once ingested, the parasites attach to the lining of the buccal cavity and then migrate out to their preferred colonisation site on the outer surface of the fish. It is proposed that this may be an alternative route for host infection. Similarly, direct ingestion by the scavenging on infected hosts by 3-spine sticklebacks suggests another route of infection of new hosts. Although these routes of transmission may be of lesser significance, infections in the buccal cavity may be an important indicator for detection of infection and those personnel involved in screening fish for gyrodactylids should be aware that this is an area in which infections can occur. This study also demonstrated that the use of the anaesthetic 2-phenoxyethanol does not affect the number of gyrodactylids which leave the host to colonise a new host. Additionally, observations of the transmission process suggest that turbulence produced by the movement of the fish’s fins may facilitate the transfer of detached parasites from the substrate. While this hypothesis appears to be supported by video evidence and photographic stills gathered throughout the duration of this study, further work should be conducted using particle tracking techniques to determine the efficacy of using a vortex effect as a means of colonising new hosts. Field sampling processes may have an effect on this type of research, giving rise to problems with the accurate diagnosis, management and control of gyrodactylids in a variety of fish. Gyrodactylus infected specimens of 3-spine stickleback (Gasterosteus aculeatus L.), minnows (Phoxinus phoxinus L.) and stone loach (Barbatula barbatula L.) from one Scottish river were cohabited. The study found that small numbers of Gyrodactylus do transfer to atypical hosts. This study highlights that personnel involved in fish disease surveillance programmes should be aware of the consequences of transporting multiple species in the same transport vessel as gyrodactylids may infect species previously thought to be resistant. Equally, diagnosticians should be aware of the fact that atypical species may act as temporary hosts and that their gyrodactylid fauna should not be assumed. Non-feeding life-cycle stages, such as the dispersal stages of parasites, are dependant for survival upon finite energy reserves gathered during feeding phases. Thus, those individuals with more limited reserves will die sooner and consequently have less time available to find a new host once detached. At this stage, the principal energy reserves in gyrodactylids are stored as large lipids droplets. Confocal laser scanning microscopy (CLSM) has been used to investigate the distribution of lipid droplets in Gyrodactylus, which have migrated off their fish host, testing the hypothesis that these droplets function as a proxy for the nutritional state. This study, demonstrated that the lipid droplets were particularly associated with the gut and that there is a significant variability in the volume of stored lipid carried out by each individual. Transmission Electron Microscopy (TEM) showed that gyrodactylids carry lipid droplets at all stages of their life cycle, including at release from the birth pore. It is likely that transferring worms require stored energy reserves to survive in the event of failure to establish contact with a new host. These reserves could allow the parasite to survive without a host for several days. As gyrodactylids appear to respond to a range of stimuli including vibration and chemicals released from the host, the presence or absence of such cues may have consequences on the rates of Gyrodactylus transmission. If these chemical stimuli can be identified and then mimicked or blocked, then this may offer potential opportunities for the control of gyrodactylid behaviour and for disrupting their transmission to new hosts. Baseline gyrodactylid behaviour, in the absence of a host, was determined under white light and infrared. This was achieved using a specially constructed arena and purpose written image analysis software to analyse parasite movement under different lighting conditions. The study found that gyrodactylids were more active in the dark than in light conditions, typically displaying longer, more sinuous tracks under red light than under white light. To begin investigating the effect of chemical presence on gyrodactylid behaviour, the activity of octopaminergic agonists and antagonist which bind to muscle receptors and alter muscle activity, were assessed. The impact of octopamine hydrochloride, clonidine hydrochloride, amitraz and, a toxic reference, chlordimeform, over a range of concentrations (0.2 to 3.2µM/L) were assessed on gyrodactylid behaviour. All of the four chemicals affected Gyrodactylus and produced muscle tetanus, causing muscle spasms when extension was attempted. Prolonged exposure resulted in death. Only the highest concentration of chlordimeform, the toxic reference, affected 100% of Gyrodactylus after 24 hours. After 48 hours, all of the Gyrodactylus treated with chlordimeform were either affected, moribund or dead. Amitraz was more toxic than chlordimeform with 80% of Gyrodactylus being dead after 24 hours at the highest concentration. After 48 hours 100% of Gyrodactylus exposed to 3.2 µm/L amitraz were dead, and up to 80% were dead in those exposed to lower concentrations; with no parasites being left unaffected. Although these particular compounds are toxic to fish, the effect of these agonistic chemicals on Gyrodactylus behaviour and survival is interesting and suggests that a closely related compound that is safe for use against fish may offer a potential treatment for the control of G. salaris infections in rivers. An ultrastructure study was undertaken to contribute to the current understanding of gyrodactylid ultrastructure. The findings of this research require broad understanding of gyrodactylid behaviour for their interpretation. Photographic evidence was gathered using transmission and electron microscopy. From these results, it is clear that Gyrodactylus gasterostei on a three-spine stickleback host will respond to a range of stimuli (i.e. vibration or chemical cues released from the host) in their assessment of host suitability.
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Nahallage, Charmalie A. D. "Stone handling behavior in Japanese macaques: biological, environmental and social perspectives of a cultural behavior." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/124370.
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Kyoto University (京都大学)0048
新制・課程博士
博士(理学)
甲第14126号
理博第3339号
新制||理||1491(附属図書館)
UT51-2008-N443
京都大学大学院理学研究科生物科学専攻
(主査)准教授 Huffman Michael Alan, 教授 渡邊 邦夫, 教授 林 基治
学位規則第4条第1項該当
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Raja, Sathishkumar [Verfasser]. "The neuronal basis of spontaneous flight behavior in Drosophila / Sathishkumar Raja." Berlin : Freie Universität Berlin, 2013. http://d-nb.info/1036130460/34.
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Hidayat, Egi. "On Identification of Biological Systems." Doctoral thesis, Uppsala universitet, Avdelningen för systemteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-215699.
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System identification finds nowadays application in various areas of biological research as a tool of empiric mathematical modeling and model individualization. A fundamental challenge of system identification in biology awaits in the form of response variability. Furthermore, biological systems tend to exhibit high degree of nonlinearity as well as significant time delays. This thesis covers system identification approaches developed for the applications within two particular biomedical fields: neuroscience and endocrinology. The first topic of the thesis is parameter estimation of the classical Elementary Motion Detector (EMD) model in insect vision. There are two important aspects to be taken care of in the identification approach, namely the nonlinear dynamics of the individual EMD and the spatially distributed structure of multiple detectors producing a measurable neural response. Hence, the suggested identification method is comprised of two consecutive stages addressing each of the above aspects. Furthermore, visual stimulus design for high spatial excitation order has been investigated. The second topic is parameter estimation of mathematical model for testosterone regulation in the human male. The main challenges of this application are in the unavailability of input signal measurements and the presence of an unknown pulsatile feedback in the system resulting in a highly nonlinear closed-loop dynamics. Semi-blind identification method has been developed based on a recently proposed pulse-modulated model of pulsatile endocrine regulation. The two system identification problems treated in the thesis bear some resemblance in the sense that both involve measured signals that can be seen as square-integrable functions of time. This property is handled by transforming the signals into the Laguerre domain, i.e. by equivalently representing the functions with their infinite Laguerre series.
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Barbany, Puig Montserrat. "Three Dimensional Simulitary of Molecules with biological interest on the basis of molecular interaction potentials." Doctoral thesis, Universitat Pompeu Fabra, 2006. http://hdl.handle.net/10803/7146.
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Una de les àrees més prometedores en recerca biomèdica i farmacèutica és el disseny molecular computacional, que intenta establir relacions entre propietats físico-químiques i activitat biològica. L'èxit d'aquestes tècniques depen críticament de la qualitat de la descripció molecular. En aquest sentit, metodologies basades en potencials d'interacció molecular (MIP) són eines útils per la comparació de compostos que presenten comportaments biològics semblants.
Aquest projecte desenvolupa eines per comparar molècules basades en la caracterització de llurs MIPs. El programa de similaritat molecular MIPsim ha estat desenvolupat i aplicat a diferents problemes biològics.
Aquesta tesi consisteix en quatre estudis científics que mostren l'ús del MIPSim en aliniament molecular, catalisi enzimàtica, en acoratge de molècules dins el lligand i en estudis 3D-QSAR.
One of the most promising areas in biomedical and pharmaceutical research is computer assisted molecular design, which tries to stablish relationships between physicochemical properties and biological activity.
The success of these techniques depends critically on the quality of the molecular description. In this sense, methodologies based on molecular interaction potentials (MIP) are useful tools for the comparison of compounds displaying related biological behaviours.
This project aims to develop tools to compare 'molecules based on the characterization 'of their MIPs. To this end, the molecular similarity program MIPSim has been further developed and applied to different biological problems.
This thesis consists on four scientific studies showing the use of MIPSim for molecular alignment, enzymatic catalysis, ligand-protein docking and 3D-QSAR analyses.
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Ghezzo, Alessandro <1962>. "The biological basis of autism spectrum disorders: evaluation of oxidative stress and erytrocyte membrane alterations." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7116/.
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This case-control study involved a total of 29 autistic children (Au) aged 6 to 12 years, and 28 gender and age-matched typically developing children (TD). We evaluated a high number of peripheral oxidative stress parameters, erythrocyte and lymphocyte membrane functional features and membrane lipid composition of erythrocyte. Erythrocyte TBARS, Peroxiredoxin II, Protein Carbonyl Groups and urinary HEL and isoprostane levels were elevated in AU (confirming an imbalance of the redox status of Au); other oxidative stress markers or associated parameters (urinary 8-oxo-dG, plasma Total antioxidant capacity and plasma carbonyl groups, erythrocyte SOD and catalase activities) were unchanged, whilst peroxiredoxin I showed a trend of elevated levels in red blood cells of Au children. A very significant reduction of both erythrocyte and lymphocyte Na+, K+-ATPase activity (NKA), a reduction of erythrocyte membrane fluidity, a reduction of phospatydyl serine exposition on erythrocyte membranes, an alteration in erythrocyte fatty acid membrane profile (increase in MUFA and in ω6/ω3 ratio due to decrease in EPA and DHA) and a reduction of cholesterol content of erythrocyte membrane were found in Au compared to TD, without change in erythrocyte membrane sialic acid content and in lymphocyte membrane fluidity. Some Au clinical features appear to be correlated with these findings; in particular, hyperactivity score appears to be related with some parameters of the lipidomic profile and membrane fluidity, and ADOS and CARS score are inversely related to peroxiredoxin II levels. Oxidative stress and erythrocyte structural and functional alterations may play a role in the pathogenesis of Autism Spectrum Disorders and could be potentially utilized as peripheral biomarkers.
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Swope, Joseph. "Self-Hypnosis and Volitional Control of Finger Temperature Among Adults." ScholarWorks, 2011. https://scholarworks.waldenu.edu/dissertations/1051.
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Raynaud's disease is a condition in which circulation to the hands becomes restricted, causing an uncomfortable sense of cold and occasionally injury. The cause of Raynaud's disease is unknown. Earlier studies have shown that hetero-hypnosis is effective in the treatment of Raynaud's disease. Cost and access to providers limit such a treatment's availability. Theories of hypnosis suggest that self-hypnosis underlies all hypnotic processes. This study examined the utility of self-hypnosis and focused attention on the volitional control of hand temperature. Forty-three adult participants ranging in age from 19 to 77 years with no hypnosis experience were randomly divided into 2 groups; 20 completed the study. Eleven participants listened to a self-hypnosis recording and 9 listened to a mostly blank recording containing periodic instructions to concentrate on controlling finger temperature. A paired samples t test showed a significant difference in means between pre- and post-treatment ability. A second t test did not show a significant difference in means between the groups' ability. Analysis of survey data did not show a significant relationship between participant demographic data and ability to control finger temperature. However, analysis of participant survey responses did show that self-hypnosis was significantly more enjoyable than conscious concentration, which suggests that self-hypnosis has greater potential for adoption if used in the treatment of Raynaud's disease. Because self-hypnosis was found to be enjoyable and effective it may be superior to other treatments that are unpleasant or have pharmacological side effects. These findings will inform sufferers of Raynaud's disease and researchers in their efforts to treat the disease. The positive social change implications of this study are to expand treatment options for a disease that affects 4% of the world's population.
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Kowalko, Johanna Elizabeth. "The genetic basis of behavior in the blind Mexican cavefish, Astyanax mexicanus." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11104.
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In recent years, considerable progress has been made towards understanding the genetic basis of the evolution of morphological traits. In contrast, relatively little is known about how behavioral traits evolve. Astyanax mexicanus, a species of fish that exists in both surface and cave forms, is an ideal system to study behavioral evolution. Surface and cave morphs of Astyanax mexicanus differ in a variety of morphological and behavioral traits. They are interfertile, allowing for genetic analysis of the evolution of these traits. Finally, Astyanax mexicanus exists in multiple, independently evolved cave populations, providing an excellent system for studying convergent evolution.
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Metz, Hillery. "The Genetic Basis of Behavior: Burrow Construction in Deer Mice (Genus Peromyscus)." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467514.
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Understanding how complex, adaptive behavior evolves is a major goal of biological research. Phenotypic differences between closely-related species often arise due to evolution by natural selection and can be a powerful resource for understanding biological diversity and its mechanistic underpinnings. In this dissertation, I capitalize on striking behavioral differences between two interfertile sister species of Peromyscus rodents. I pursue the proximate mechanisms underlying this behavioral adaptation by investigating both the ontogeny and genetics of innate differences in burrow construction behavior in Peromyscus polionotus and P. maniculatus.
In Chapter 1, I compare the ontogeny of burrow construction behavior of Peromyscus polionotus and P. maniculatus across early development. I find that P. polionotus begins burrowing precociously (as early as 17 days of age) compared to P. maniculatus (27 days of age), despite P. polionotus being physically smaller and less active in a wheel running assay. Furthermore, juvenile P. polionotus constructed long burrows complete with species-specific escape tunnels. Interspecific cross-fostering did not alter the developmental trajectory of either species, indicating that these differences are innate. Moreover, F1 hybrids followed the behavioral ontogeny of P. polionotus, indicating that precocious burrow construction segregates in a P. polionotus-dominant manner. Finally, I show that a quantitative trait locus (QTL) associated with adult tunnel length in these species is predictive of precocious digging in recombinant F2 hybrids, demonstrating that either a single pleiotropic locus or a group of tightly-linked genes control behavioral differences across life stages in P. polionotus.
In Chapter 2, I dissect the genetic architecture of this complex behavior in adult animals using an experimental cross. By introgressing the burrow architecture of P. polionotus into the genetic background of P. maniculatus, I analyze the underlying genetic architecture of differences in burrowing behavior, and show that escape tunnels are likely a threshold trait. Next, I use a novel image-based analysis to collect measurements of burrow shape and demonstrate the utility of a more rigorous measurement of extended phenotypes.
Finally, in Chapter 3, I combine two forward-genetics approaches—QTL mapping and transcriptome analysis—to nominate specific candidate genes for the differences in burrowing behavior between P. polionotus and P. maniculatus. Using a large advanced backcross mapping population (n=751), I detect five QTL contributing to differences in burrow architecture between these species: three loci for entrance tunnel length variation, and two loci for escape tunnel length. In the transcriptome study, I focus on gene expression in F1 hybrids to detect allele-specific expression (ASE), as ASE in an F1 hybrid indicates cis-regulatory differences between the parental lineages. I find widespread bias favoring expression from the P. polionotus-allele in F1 hybrid brains, which may be a molecular reflection of P. polionotus-like burrowing behavior of hybrids. Finally, I use ASE to nominate candidate genes within the detected QTL regions, and find genes related to behavioral disorders, circadian rhythms, and activity patterns; these genes represent promising candidates for future functional studies.Biology, Organismic and Evolutionary
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Chittum, Harold S. "A Molecular Basis for Erythromycin Sensitivity and Resistance in Escherichia Coli." Digital Commons @ East Tennessee State University, 1993. https://dc.etsu.edu/etd/2655.
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The effect of erythromycin on the 50S ribosomal subunit during cell growth has been extensively investigated. Sucrose density gradient analysis of ribosomes formed in the presence and absence of the drug revealed a 50S specific assembly defect is partially responsible for erythromycin's inhibitory effects on wild type cells. Examination of two erythromycin-resistant mutants of E. coli (N281 and N282) revealed that mutant N281 (L22 mutant) but not N282 (L4 mutant) was assembly defective in the presence of the drug, although only at much higher drug concentrations (300 ug/ml vs. 75 ug/ml for wild type cells). The altered genes from each mutant have been isolated and sequenced. The L22 mutant was found to contain a 9 bp deletion which eliminated codons 82-84, and the sequence Met-Lys-Arg from the protein. The L4 mutant had an A to G transition mutation in codon 63 resulting in a Lys to Glu change in the protein. Complementation of each mutant by their respective wild type genes resulted in an increased sensitivity to the drug in the partial diploid strains. Two other macrolide antibiotics (oleandomycin and spiramycin) were also examined but revealed no apparent assembly effect on wild type cells. The MLS antibiotics also appeared to be unable to effect assembly. However, the erythromycin derivative azithromycin showed a similar effect on assembly to that of the parent compound although clarithromycin (another erythromycin derivative) did not. These results suggest erythromycin and azithromycin effect assembly through ribosomal protein L4 and to a lesser extent through protein L22.
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Matti, Sakari Itkonen. "Application of Biological Control Principle in Understanding of Human Behavior Modulations." Kyoto University, 2020. http://hdl.handle.net/2433/259069.
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Li, Xiao Qing. "DNA ploidy as a predictor for biological behavior of musculoskeletal tumors." Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1057946627.
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Ahmed, Hafiz. "Modeling and synchronization of biological rhythms : from cells to oyster behavior." Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10129/document.
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La modélisation, l’analyse et le contrôle des oscillations, notamment des rythmes biologiques ont été étudiés dans cette thèse. La thèse est divisée en deux parties. Dans la première partie, motivée par un problème pratique de la surveillance de l'environnement côtier, cette thèse considère les rythmes biologiques des huîtres. En utilisant les informations des rythmes biologiques, une solution de surveillance environnementale indirecte en utilisant les huîtres comme bio-capteur a été proposé. La solution proposée se base sur l'estimation de la perturbation par la modélisation du rythme biologique des huîtres par un oscillateur de Van der Pol. Une limite inhérente de cette approche est que celle-ci fonctionne uniquement grâce à la détection des comportements anormaux. Cependant les comportements anormaux ne sont pas tous liés à la pollution. Nous considérons donc la détection d'un type particulier de comportement oscillatoire anormal à savoir la ponte, qui est un phénomène naturel et non lié à la pollution. Le premier problème de la deuxième partie est la robustesse des oscillations dans la division cellulaire. Les oscillations persistent dans les oscillateurs génétiques après la division cellulaire. Dans cette thèse, nous fournissons des conditions d'analyse qui garantissent la synchronisation de phase après la division cellulaire. Enfin, nous considérons le problème de la synchronisation des systèmes multi-stables en utilisant l’Input-to-State Stability (ISS). En utilisant une généralisation récente de la théorie de l'ISS pour les systèmes multi-stables, nous proposons des conditions suffisantes pour la synchronisation des systèmes multi-stablesModeling, analysis and control of oscillations, notably biological rhythms have been studied in this thesis. The thesis is divided into two parts. In part-I, motivated by a practical problem of environmental monitoring of coastal environment, this thesis considers the biological rhythms of oysters. Using the information of biological rhythms, an indirect environmental monitoring solution using oysters as bio-sensor has been proposed. The proposed solution works on estimating the perturbation by modeling the biological rhythm of oysters through Van der Pol oscillator model. An inherent limit of this approach is that it works through detecting abnormal behavior only. However abnormal behaviors are not all related to pollution. So, we consider the detection of a particular type of abnormal oscillatory behavior i.e. spawning (behavior during reproduction) which is a natural phenomenon and not related to pollution. In part-II, oscillations are studied from a theoretical point of view. The first problem of this part is the robustness of oscillations under cell division. Oscillations persist in genetic oscillators after cell division. In this thesis, we provide analytical conditions that guarantee phase synchronization after cell division using Phase Response Curve (PRC) formalism. Finally we consider the problem of synchronization of multi-stable systems using Input-to-State (ISS) stability tool. Using a recent generalization of ISS theory for multi-stable systems, we propose sufficient conditions for the synchronization of multi-stable systems. As a side result, this work has been applied for the global synchronization of the Brockett oscillator
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Kurniawan, Veldri. "The neural basis of multisensory spatial and feature-based attention in vision and somatosensation." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/40755/.
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Attention refers to the cognitive processes that prioritise a subset of available sensory information for enhanced processing, and which can be directed towards spatial locations, object features, time, or other aspects of the environment. While the majority of research has focused on studying attention within sensory modalities, a growing body of evidence has demonstrated that attention interact with multisensory processes. Several neuroimaging studies have shown that higher cortical regions activated during attention to multiple sensory modalities overlap significantly with the dorsal and ventral frontoparietal regions activated during visual attention tasks. This evidence has led some researchers to propose the existence of supramodal frontoparietal system that controls the deployment of attention across various sensory modalities. Although influential, this hypothesis has been challenged by other studies that discovered evidence for modality-specific regions in the parietal cortex. In this thesis, I investigated the generality and specificity of the frontoparietal network associated with multisensory spatial and feature-based attention, in vision and touch, by applying multivoxel pattern analysis (MVPA) to fMRI data. Recent studies have successfully demonstrated that MVPA methods could be used to discriminate various experimental conditions from weak distributed patterns of activity within overlapping cortical regions found by univariate fMRI analysis. Here, I applied similar logic to examine overlapping frontoparietal regions activated during multisensory attention. Contrary to the supramodal hypothesis, the results supported the existence of modality-specific systems in the posterior parietal cortex during both attention to spatial locations and stimulus features. Additional evidence for modality-specific processes was also indicated in the patterns of top-down modulatory activity in visual cortex. Overall, the current findings supported the view that both modality-specific and potentially supramodal frontoparietal regions work in concert to selectively bias activity in sensory cortical regions during various states of attention.
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Masureel, Matthieu. "Molecular basis of secondary multidrug transport." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209479.
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The Major Facilitator Superfamily groups a vast number of secondary transporters that import or export distinct substrates. Among these, multidrug antiporters constitute a peculiar class of transporters, both because of their multispecificity, recognizing structurally very diverse substrates, and because of their transport mechanism, that relies on bilayer-mediated extrusion of cytotoxic compounds. An accurate and detailed description of the conformational changes that underlie the transport cycle is still lacking and the structural basis for energetic coupling in these transporters has not been elucidated, with so far only limited crystallographic evidence available. We investigate the molecular basis of secondary multidrug transport with biochemical and biophysical studies on LmrP, a Major Facilitator Superfamily multidrug transporter from Lactococcus lactis. We used extensive continuous-wave electron paramagnetic resonance and double electron-electron resonance measurements on a library of spin-labeled LmrP mutants to uncover the conformational states involved in transport and to investigate how protons and ligands shift the equilibrium between conformers to enable transport. We find that the transporter switches between outward-open and outward-closed conformations depending on the protonation states of specific acidic residues forming a transmembrane protonation relay. We observe that substrate binding restricts the conformational freedom of LmrP and induces localized conformational changes. Our data allows to build a model of secondary multidrug transport wherein substrate binding initiates the transport cycle by opening the extracellular side to protons. Subsequent protonation of membrane-embedded acidic residues induces substrate release to the extracellular side and triggers a cascade of conformational changes that culminates in a proton release to the intracellular side. Parallel to this, we have optimized our purification and expression protocol in order to set up crystallization trials on LmrP. Through extensive screening and optimization of the lipidation state of LmrP, using ad hoc methods for sample preparation, we were able to obtain low-resolution diffracting crystals. By improving our lipidation technique and modifying the lipid composition we further improved crystal quality. Other factors such as ligand addition, the presence of secondary detergent and additives for controlling phase separation and nucleation were tested, paving the way to high resolution structure determination of LmrP.Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Idiculla, Thomaskutty B. "Gender Invariance of Behavior and Symptom Identification Scale Factor Structure." Thesis, Boston College, 2008. http://hdl.handle.net/2345/1815.
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Thesis advisor: Thomas O'HareThe Behavior and Symptom Identification Scale 24 (BASIS-24) is a psychiatric outcome measure used for inpatient and outpatient populations. This 24-item measure comprises six subscales: depression/functioning; interpersonal relationships; self-harm; emotional lability; psychosis; and substance abuse. Earlier studies examined the reliability and validity of the BASIS-24, but none empirically examined its factor structure across gender. The purpose of this study was therefore to assess the construct validity of the BASIS-24 six-factor model and find evidence of configural, metric, strong and strict factorial invariance across gender. The sample consisted of 1398 psychiatric inpatients that completed BASIS-24 at admission and discharge at 11 facilities nation-wide. Confirmatory factor analyses were used to test measurement invariance of the BASIS-24 six-factor model across males and females. The single confirmatory factor analysis showed the original six-factor model of BASIS-24 provided an acceptable fit to the male sample at admission (RMSEA=0.058, SRMR=0.070, CFI=0.975, NNFI=0.971 and GFI=0.977) and at discharge (RMSEA=0.059, SRMR=0 .078, CFI=0.977, NNFI=0.972, and GFI=0.969). The goodness-of-fit indices for the female group at admission (RMSEA=0.055, SRMR=0.067, CFI=0.980, NNFI=0.976, and GFI=0.983), and at discharge (RMSEA=0.055, SRMR=0.079, CFI=0.98, NNFI=0.977, and GFI=0.971) also revealed that the six factor model fit reasonably well to the data. The goodness-of-fit indices between the unconstrained and constrained models showed that all four multi-group models were equivalent for both male and female samples at admission and discharge in terms of goodness-of-fit examined through the ΔCFI and that all of them show an acceptable fit to the data. The decrease in CFI was <0.008 for admission sample and <0.003 for discharge sample and both fell below the 0.01 cut-off. This indicates that the configural, metric, as well as the strong and strict factorial invariance of BASIS-24 exist across males and females. The two important contributions of the present study are: 1) BASIS-24 can be used as a reliable and valid symptom measurement tool in assessing psychiatric inpatient populations which can compare quantitative differences in the magnitude of patient symptoms and functioning across genders; 2) the current study provides an example of useful statistical methodology for examining specific questions related to factorial invariance of the BASIS-24 instrument across gender. Implications of social work practice and research are discussed
Thesis (PhD) — Boston College, 2008
Submitted to: Boston College. Graduate School of Social Work
Discipline: Social Work
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Celone, Kim A. "Characterizing the brain-behavior basis of habit learning in women with eating disorders." Thesis, Boston University, 2012. https://hdl.handle.net/2144/32012.
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Thesis (Ph.D.)--Boston UniversityPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
This thesis examined brain function in women with eating disorders who meet clinically significant subthreshold DSM-IV criteria for bulimia nervosa (Sub-BN) by investigating the acquisition of motor and cognitive habits. Habit learning is an implicit learning process that is associated with a pattern of parallel processing in fronto-striatal implicit memory system and the medial temporal lobe (MTL) explicit or associative memory system. Neuropsychological and neuroimaging evidence suggest fronto-striatal dysfunction plays a role in the formation and maintenance of maladaptive behaviors and thought patterns in eating disorders. Eighteen Sub-BN and nineteen healthy control women (MC) performed both motor and cognitive habit learning tasks during a single fMRI session. The first experiment examined motor-sequence habit learning via the serial reaction time task (SRTT). The results revealed similar habit learning performance between Sub-BN and healthy control women; however Sub-BN participants demonstrated decreased prefrontal cortex-striatal activation and corresponding MTL increases during habit formation. The second experiment examined regional brain activity during cognitive habit learning on the weather prediction task (WPT), which creates a competing response environment. Findings suggest Sub-BN participants show increased overall caudate nucleus and dorsolateral prefrontal cortex (DLPFC) activation, in addition to initial decreased involvement of the MTL and later increased involvement of the DLPFC. The third experiment utilized functional and effective network connectivity to further explore the data from experiments one and two. The results provide additional support for a disruption in MTL and fronto-striatal memory system interactions, as well as additional disruptions in patterns of "Default Mode Network" and cerebellar connectivity. This thesis demonstrates that during habit learning, disrupted interactions between MTL and fronto-striatal memory systems may be characteristic of the underlying neurobiology of eating disorders. High perfectionism and low self efficacy may result in sensitivity to uncertainty in individuals with eating disorders that alters the adaptive mechanism that controls the utilization of memory systems. In addition, changes in "Default Mode Network" connectivity, as well as increased affective cerebellar connectivity may represent mechanisms that maintain overall beliefs regarding uncertainty. Together, these findings represent viable mediators of the rigid and preoccupying thoughts and behaviors characteristic of individuals with eating disorders.
2031-01-02
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Scott, Lena. "Plasticity in the dopamine 1 receptor system : behavior and cell biological studies /." Stockholm, 2004. http://diss.kib.ki.se/2004/91-7140-060-5/.
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Sewell, Mary Kathryn. "The localization and behavior of fluorescently tagged magnetic nanoparticles in biological systems." Thesis, [Tuscaloosa, Ala. : University of Alabama Libraries], 2009. http://purl.lib.ua.edu/103.
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Adedipe, Folukemi Ebunoluwa. "Investigation of ecological behavior of two Coccinellidae beetle adults for biological control." Morgantown, W. Va. : [West Virginia University Libraries], 2009. http://hdl.handle.net/10450/10491.
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Thesis (M.S.)--West Virginia University, 2009.Title from document title page. Document formatted into pages; contains vii, 60 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
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Stich, Daniel Stephen. "Behavior and population dynamics of grass carp incrementally stocked for biological control." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/34212.
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Grass carp Ctenopharyngodon idella have been stocked throughout the world due to their utility as a biological control. In the United States, the species has been used to successfully control invasive, aquatic weeds such as hydrilla Hydrilla verticillata. Despite the large body of research surrounding the use of grass carp, few studies have demonstrated widely applicable methods for evaluating the success of weed control based on grass carp behavior and population dynamics. Classic methods of biological control using grass carp often rely on a single, large stocking of fish. Few of these studies have demonstrated success in achieving intermediate levels of weed control. Managers would be better equipped to make decisions regarding stocking and maintenance grass carp populations with better information about behavior, survival, and population structure. Improved decision making could result in reduced cost and increased effectiveness of stocking. In order to examine current knowledge gaps for management, I investigated the movements and habitat use of grass carp, post-stocking survival, age-specific survival rates, and population dynamics of grass carp in Lake Gaston, North Carolina and Virginia.
I characterized relationships between grass carp behavior and environmental factors using radio-telemetry. The average rate of movement for grass carp in Lake Gaston was about 137 m/d. Rapid dispersal after stocking was followed by long periods of no movement. However, when time after stocking was held constant in models of behavior, fish moved about 200 m/d more in the second year after stocking than in the first year, and were found closer to shore. On average, grass carp were found about 40 m from shore in about 2.5-3.5 m of water, although mean depth of water at grass carp locations varied seasonally, being shallowest in summer and deepest in winter. Although depth of water at grass carp locations did not vary by stocking location, Grass carp were found closer to shorelines in the upper reservoir than in the lower reservoir. I found significant relationships between grass carp behavior and hydrological processes such as lake elevation and dam releases in the reservoir, as well as with other environmental factors such as water temperature, photoperiod, and weather conditions. The results of this study should be useful in better understanding how behavior can affect management decisions. Specifically, grass carp behavior appears to change with age and environmental conditions within large reservoir systems. Future research should focus more closely on the effects of large-scale flow dynamics on grass carp behavior.
I estimated age-1 survival of grass carp from mark-recapture models designed for radio-tagged animals, and characterized relationships between age-1 survival and factors under the control of management, such as stocking locations and size at stocking. . According to the most-plausible model developed in this study, survival of age-1 grass carp in Lake Gaston varied throughout the year, and the probability of an individual grass carp surviving to the end of its first year (±SE) was 0.57(±0.10). According to the second-most-plausible model developed in this study, grass carp survival varied between stocking locations, and was twice as high in the upper reservoir (0.87±0.09) than in the lower reservoir (0.43±0.11). The differences in survival between stocking locations suggest that the cost-effectiveness of grass carp stocking could be improved by focusing stocking efforts in specific regions of Lake Gaston. Furthermore, none of the models developed in this study that incorporated the effects of size (length and weight) or condition factor accounted for a meaningful amount of the total model weights. These results suggest that costs of grass carp stocking could be reduced in Lake Gaston by using a smaller minimum size (352 mm, TL) than is commonly referred to in the literature (450 mm, TL).
I used grass carp collected by bowfishers in Lake Gaston to characterize the age, growth, and survival of grass carp in the system. From these data, I characterized relationships between fish population dynamics and annual hydrilla coverage. Grass carp collected from Lake Gaston ranged in age 1-16 years. Growth of grass carp in Gaston was described by the von Bertalanffy growth function as Lt = 1297(1-e -0.1352 (t+1.52)). I estimated mortality from the von Bertalanffy growth parameters using methods based on growth, temperature, and age; and with each mortality estimate I estimated population size and standing biomass of grass carp. Use of age-specific mortality rates produced lower estimates of grass carp numbers and standing biomass in Lake Gaston than did the use of a single, instantaneous mortality rate for all ages. I determined that growth of grass carp slowed considerably after the fourth year and that slowed growth, in combination with changes in mortality, resulted in a decrease in the amount of hydrilla controlled by a given cohort after four years in Lake Gaston. This phenomenon resulted in an approximately linear relationship between the biomass of grass carp at year i and hectares of hydrilla at year i+3. Based on this relationship, I predicted that the biomass of grass carp necessary to reduce hydrilla coverage to the target level of 120 ha in Lake Gaston is about 91,184 kg (±38,146 kg) and that the current biomass of grass carp in Lake Gaston is about 108,073 kg (±3,609 kg). I conclude that grass carp biomass is at or near levels that should reduce hydrilla coverage to 120 ha between 2013 and 2018. This research provides an effective means for synthesis of information that is critical to understanding sterile, triploid grass carp populations when assumptions of other methods cannot be met. The results of this study should be of immediate utility to hydrilla management efforts in Lake Gaston and other systems. Furthermore, the age-specific mortality rates developed in this study should be useful as starting values for grass carp management in similar systems.Master of Science
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Reeves, Justin. "Plant Finding Behavior of Phytophagous Insects and Biological Control of Aquatic Plants." Kent State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=kent1285168402.
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Keeley, Brian Lee. "Cognitive science as the computational neuroethology of intelligent behavior : why biological facts are important for explaining intelligent behavior /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1997. http://wwwlib.umi.com/cr/ucsd/fullcit?p9804512.
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Ross, Graham Andrew. "An investigation into the biological basis of #late effect' endpoints in the rectum of rats after radiation." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339103.
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