Biological Sciences electronic theses and disserations (MU)
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The items in this collection are the theses and dissertations written by students of the Division of Biological Sciences. Some items may be viewed only by members of the University of Missouri System and/or University of Missouri-Columbia. Click on one of the browse buttons above for a complete listing of the works.
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Item Structure and function of FtsZ and interacting protein partners in cell division of agrobacterium tumefaciens(University of Missouri--Columbia, 2024) Aubry, Brody; Brown, Pamela J.B.[EMBARGOED UNTIL 12/01/2025] Our understanding of bacterial cell division arises from research spanning over five decades of research from multidisciplinary approaches including genetics, biochemistry, cell biology, biophysics, and computational modeling. While the goal of most of this prior research has been to identify key players in bacterial cell division, most of our current understanding of cell division in diderm bacteria is based on research focused on Escherichia coli, a Gammaproteobacteria. The model of cell division built off the E. coli work is expansive and describes tens of core proteins critical for cell division, as well as a myriad of accessory proteins. Recent exploration of cell division in other diderm bacteria reveals that a summative model derived from E. coli is not sufficient. In this dissertation, we detail unique features for bacterial cell division found in Alphaproteobacterial members. Specifically, we focus on duplications of FtsZ, expansion of FtsZ C-Terminal Linker (CTL) domains, and the function of FzlA, a clade-specific FtsZ binding partner. Chapter 1, provides an overview comparing features involved in cell division in three diderm bacteria, E. coli, Caulobacter crescentus, and Agrobacterium tumefaciens, before introducing notable features of the predicted A. tumefaciens model that is explored in this dissertation. In chapter 2, we discuss FtsZ duplications and present our findings on toxicity induced by overexpression of FtsZ1. Chapter 3 explores the expansion of CTL domains in FtsZ proteins across the Alphaproteobacterial class, with a comprehensive analysis of the CTL function in A. tumefaciens. In chapter 4, we describe the Alphaproteobacterial FtsZ-binding partner FzlA and its functions in A. tumefaciens, in chapter 4. We conclude with chapter 5 by providing a summary of the contributions made to the field throughout this dissertation work.Item Spectral analysis of fluorescent substances in the eyes of flies and man(University of Missouri--Columbia, 1982) Miller, Gregory Vern; Stark, William S."Summary. The compound eyes of flies are known to contain fluorescing substances (e.g. Franceschini 1977). Measurements of changes in fluorescence and transmission occurring in the eye while it is exposed to light were used to discover properties of photoreceptors, predominantly Rl-6. Flies receiving intense light treatment and vitamin A deprivation were used to determine which components of compound eye fluorescence are actually associated with light transducing pigments. Also microscpectrofluorometry was used to measure the emission spectra of fluorescing substances in the eyes of white-eyed Drosophila. Emission was measured using 365 nm excitation. Careful calibrations of our microspectrofluorometer were used to calculate corrected spectra. Emission measurements from the deep pseudopupil, a means of visualizing receptive elements, were taken before and after treatment with intense ultraviolet light in both normal and vitamin A deprived flies. Two emission maxima exist in the eyes of normal flies: a blue peak (max = 460 λ) and a red peak ( max = λ650 nm) (Fig. 8). The long wavelength (red) emission is absent however, in vitamin A deprived flies (Stark et al. 1979c, Fig. 8). Intense UV treatment of normal flies reduced the blue emission and eliminated the red emission (Fig. 6). UV treatment of vitamin A deprived flies caused the same reduction in blue fluorescence (Fig. 9). Since vitamin A deprivation eliminates most photopigment (e.g. Harris et al. 1977) and UV sensitizing pigment (e.g. Stark et al. 1977) this blue emission is from substances unrelated to photoreception. Excitation spectra for the >570 nm (red) fluorescence were also measured in flies before and after intense UV treatment. The excitation difference spectrum maximum was at =350 nm with a minor second peak at =514 nm (Fig. 12) providing some evidence that the red fluorescence could be from the UV sensitizing pigment. Our findings indicate that the red, photopigmentrelated, component of our emission spectra comes from metarhodopsin (Fig. 13) and/or UV sensitizing pigment (Fig. 12). Much more intense exciting light can create other fluorescing substances. Intense blue and UV light destroys photopigment and produces a red-emitting substance called metarhodopsin’ (M', e.g. Franceschini et al. 1981) (see Figs. 2-5). We have also noted a surge of yellow fluorescence accompanying exposure of red eyes to the highest intensities of blue light available (Fig. 1). The source of this yellow fluorescence remains uncertain but it depends on eye color pigments. Neither M' nor these yellow emitting fluorophores contribute to the red component of our emission spectra (Figs. 6-8) however, since the intensity of the UV exciting light was much less than that necessary to create either of them."--Page 4.Item Effects of experimental autoimmune encephalomyelitis on properties and function of the mouse major pelvic ganglion neurons(University of Missouri--Columbia, 2024) Henderson, Sherryl LaVon; Schulz, DavidExperimental autoimmune encephalomyelitis (EAE) serves as a valuable mouse model for studying the pathophysiology of multiple sclerosis (MS), a chronic autoimmune disease characterized by inflammation and demyelination of the central nervous system (CNS). While EAE mimics many aspects of MS, its effects on the lower urinary tract (LUT) remain poorly understood. This study investigated alterations in lower urinary tract output, excitability of major pelvic ganglion (MPG) neurons, and expression profiles of MPG neurons in EAE. Adult female SJL/J mice were induced with EAE, and clinical scores were monitored daily. Real-time quantitative polymerase chain reaction (qPCR) was employed to analyze gene expression in MPGs, while functional bladder output and electrophysiological measurements of MPG neurons were conducted to evaluate lower urinary tract output and MPG neuron excitability. The results revealed significant changes in lower urinary tract output, with decreased urine output observed in EAE mice compared to controls. Furthermore, MPG neuron excitability was altered, with changes in passive membrane properties and action potential characteristics observed in EAE-induced animals. Analysis of gene expression profiles in MPG neurons revealed significant alterations in the mRNA levels of ion channels and receptors implicated in bladder control mechanisms. These findings provide valuable insights into the pathophysiological mechanisms underlying lower urinary tract dysfunction in EAE, suggesting potential targets for therapeutic intervention in MS-related bladder dysfunction. Further research is warranted to elucidate the complex interplay between immune-mediated CNS damage and LUT dysfunction in MS and related conditions.Item RNA polymerase II from mutant and wild type strains of Caenorhabditis elegans(University of Missouri--Columbia, 1985) Sanford, Thomas Robert; Golomb, MiriamStudies of transcription in Caenorhabditis elegans, a model organism for the study of developmental genetics, should contribute to an understanding of the developmental process in metazoans. This research describes preliminary characterization of RNA polymerase II, the enzyme that transcribes messenger RNA. RNA polymerase I, II, and III from C. elegans were isolated, and their sensitivities to the fungal toxin O-amanitin measured. Sensitivities of these enzymes to amanitin were similar to those of the coresponding RNA polymerases from vertebrates. RNA polymerase II from the nematode was 50% inhibited by 7 [mu]g/ml of the amatoxin and RNA polymerase III by 80 [mu]g/ml, whereas RNA polymerase I was insensitive to 500 [mu]g/ml of the toxin. Mutants of C. elegans were isolated which can grow and reproduce in concentrations of amanitin which arrest development of wild type worms. One of these mutant strains (DR432) was shown to contain an altered RNA polymerase II which when purified was 150 times less sensitive to the amatoxin than wild type enzyme. The mutation in DR432, ama-l(ml30), is dominant and located on linkage group IV. RNA polymerase II isolated from ama-l/+ heterozygotes contains equal proportions of two components, corresponding in amanitin sensitivity to the enzymes from DR432 and wild type. Thus, ama-1 appears to affect a subunit of RNA polymerase II. A procedure was desinged for obtaining highly purified RNA polymerase II from C. elegans. The structure of the enzyme was examined by denaturing gel electrophoresis and found to consist of two large subunits ([greater than] 100 kd), and eight smaller subunits ([less than] 50 kd). The structure of the nematode RNA polymerase II closely resembles that of the corresponding enzyme from other animals. Polyclonal antibodies against C, elegans and Drosophila RNA polymerase II were shown to bind to several subunits of the C. elegans RNA polymerase II in protein blots.Item The foraging behavior and habitat use of breeding red-shouldered hawks (Buteo lineatus) in southeastern Missouri(University of Missouri--Columbia, 1986) Parker, Margaret A.; Faaborg, John"The objective of this study was to provide more information on the habitat use and requirements of Red-shouldered Hawks in southeastern Missouri. The study was designed to learn more about the hawk's nesting habitat characteristics, foraging habitats, and prey preferences. Because of the increased food demands on breeding hawks during the nestling phase, special emphasis was put on this period. The three major areas of the hawk's habitat selection and behavior that were studied are described below."--Page 4.