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The Theory Of Character-Based Community Analysis, Valerio De Pillar
The Theory Of Character-Based Community Analysis, Valerio De Pillar
Digitized Theses
Vegetation analysis is, as a rule, comparative. Based on community components, which are plant populations, the analysis is necessarily taxonomy dependent. The fact that alternative taxonomies may, depending on the defining character set and the degree of fuzziness inherent in grouping plant individuals, lead to different perceptions has been notoriously unobserved by the dominant ecological tradition.;In the presence of choice, the question arises: which taxonomy? My main theses in the dissertation are concerned with how to answer this question. Specifically, I argue that: (1) Different taxonomic systems have conceptual justification and practical utility in vegetation studies. (2) The utility of …
The Phosphoinositide Second Messenger System And The Regulation Of The Release Of Growth Hormone From Purified Rat Somatotrophs, Michelle Brigid French
The Phosphoinositide Second Messenger System And The Regulation Of The Release Of Growth Hormone From Purified Rat Somatotrophs, Michelle Brigid French
Digitized Theses
The release of growth hormone (GH) from the somatotrophs of the anterior pituitary is controlled by two hypothalamic hormones growth hormone-releasing factor (GRF) and somatostatin (SRIF). The former stimulates, while the later inhibits the release of GH. cAMP and Ca{dollar}\sp{lcub}2+{rcub}{dollar} are second messengers for GRF. Previous reports suggested that the phosphoinositide second messenger system was an additional pathway for GRF. Our purpose was to examine the role of this system in GRF action. We used perifused dispersed anterior pituitary cells and purified somatotrophs from male rats to ask: (1) Does activation of protein kinase C stimulate the release of GH …
Covariation Of Song, Morphological, And Allozyme Frequency Characters In The Rufous-Collared Sparrow, Zonotrichia Capensis, Stephen C. Lougheed
Covariation Of Song, Morphological, And Allozyme Frequency Characters In The Rufous-Collared Sparrow, Zonotrichia Capensis, Stephen C. Lougheed
Digitized Theses
In the Rufous-collared Sparrow (Zonotrichia capensis) song dialects, defined by rate of delivery of the terminal trill, are clearly associated with variation in vegetation. The local adaptation hypothesis suggests that these dialects may act as markers for different populations adapted to different local environmental conditions predicting that there will be a correlation between the patterns of vocal and genetic variation. Thus, covariation of allozyme frequencies, and morphological (external and skeletal) measures and song characters was investigated in northwestern Argentine populations of Rufous-collared Sparrows with particular reference to possible correlations between vocal dialects and population structure. Approximately 20 males were collected …
Characterisation Of The Photosynthetic Responses Of Spring And Winter Wheat To Growth At Cold-Hardening Temperatures, Vaughan M. Hurry
Characterisation Of The Photosynthetic Responses Of Spring And Winter Wheat To Growth At Cold-Hardening Temperatures, Vaughan M. Hurry
Digitized Theses
In vivo room temperature chlorophyll a fluorescence coupled with CO{dollar}\sb2{dollar} and O{dollar}\sb2{dollar} exchange are measured to determine the effect of cold-hardening on the photosynthetic capacity and the susceptibility to photoinhibition of six cultivars of wheat (Triticum aestivum L.), covering a range of freezing tolerance. The role of the photosystem II (PSII) repair cycle in resistance to, and recovery from, photoinhibition is assessed at both low temperatures (5{dollar}\sp\circ{dollar}C & {dollar}-3\sp\circ{dollar}C) and in the presence of the 70S protein synthesis inhibitor, chloramphenicol. The effect of long-term, repeated photoinhibitory events and sustained reduction in PSII efficiency on net carbon gained is also assessed.;Winter …
Characterization And Expression Of Polyubiquitin And Ubiquitin-Fusion Protein Genes In Tissues From Control And Heat-Shocked Maize Seedlings, Ling Liu
Digitized Theses
Ubiquitin is a highly conserved, 76 amino acid, heat-stable protein found in many eukaryotic cells, including Zea mays L. Northern and dot blot hybridization analyses, using the ubiquitin coding sequence as a probe, demonstrate that the ubiquitin genes in maize are constitutively expressed at a control temperature (25{dollar}\sp\circ{dollar}C), and that heat shock (42.5{dollar}\sp\circ{dollar}C) induces an increase in polyribosome-associated ubiquitin mRNAs in the radicles (4-fold) and plumules (2-fold) of 5-day-old maize (inbred: Oh43) seedlings. These data imply that maize ubiquitin is a heat shock protein.;To assess the implication that maize ubiquitin is a heat shock protein encoded from genes whose expression …
Regulation Of Porcine Thecal Cell Steroidogenesis By Locally Produced Factors, Heidi E. Engelhardt
Regulation Of Porcine Thecal Cell Steroidogenesis By Locally Produced Factors, Heidi E. Engelhardt
Digitized Theses
Regulation of steroidogenesis (measured by radioimmunoassay) by peptides produced within the ovary was investigated in monolayer cultures of porcine thecal cells (TC). In serum-free cultures LH but not FSH stimulated accumulation of androstenedione (Ad) and progesterone (P). No further accumulation of either steroid occurred after 19h. Addition of fetal bovine serum (FBS; optimal at 1%) maintained steroidogenesis for 3-4 days, but Ad production declined, and, in the presence of LH, P production increased. IGF-I plus LH markedly enhanced P production, an effect most pronounced after 3-4 days of treatment, and not associated with increases in DNA per well. Changes in …
The Cytoskeleton In The Syncytial Epithelium Of Adult Schistosoma Mansoni, You Zhou
The Cytoskeleton In The Syncytial Epithelium Of Adult Schistosoma Mansoni, You Zhou
Digitized Theses
The surface layer of Schistosoma mansoni is an anucleated syncytium, covered by an apical plasma membrane (APM) and an overlying envelope (En), and is connected with the subsyncytial cell bodies via the membrane-bound cytoplasmic connections (MCC). This syncytium is considered as an adaptation for rapid and synchronous renewal of the surface membranes which play an important role in evasion of the host's immune system.;The present studies demonstrated the effects of the third complement component (C{dollar}\sb3{dollar}) and serotonin (5HT) on the synthesis of the discoid bodies (DBs) and multilamellar bodies (MLBs), and major syncytial inclusion bodies in vitro. With short-time incubations …
Photoinhibition Of Hardened And Non-Hardened Rye (Secale Cereale L Cv Musketeer) Studied With Isolated Thylakoids, Isolated Mesophyll Cells, And Intact Leaves, Line Lapointe
Digitized Theses
Photoinhibition of photosynthesis has been shown to be more severe when combined with other stresses. This suggests a possible correlation between the capacity to grow at low temperature and an increased resistance to photoinhibition at low temperature. Previous work has shown with chlorophyll a fluorescence that rye plants (Secale cereale L. cv Musketeer) acclimated to low temperature were more resistant to photoinhibition than non-hardened rye plants. The goal of the present study was to assess whether the morphological changes observed at the leaf level and the structural changes observed at the thylakoid level during the cold hardening process were responsible …
Statistical Inference For An Interacting Particle System, Willard J. Braun
Statistical Inference For An Interacting Particle System, Willard J. Braun
Digitized Theses
The growth patterns of cell tumors may be modelled stochastically by a multi-type lattice interacting particle system. The process is Markovian in time with spatial nearest-neighbor interactions. The cell population growth depends on several numerical parameters. These parameters specify the fission rates for individual cells and the types of resulting offspring cells.;Experimental methodology allows such a process to be observed at a specific time. It is assumed that the data obtained at this time is in the form of counts of cells of different types and locations. Based on such data, it is shown that certain statistics such as cell …
31-Phosphorous, Nuclear Magnetic Resonance Spectroscopy Studies Of Exercising Human Muscle, Gregory D. Marsh
31-Phosphorous, Nuclear Magnetic Resonance Spectroscopy Studies Of Exercising Human Muscle, Gregory D. Marsh
Digitized Theses
Phosphorous 31, nuclear magnetic resonance spectroscopy {dollar}(\sp{lcub}31{rcub}{dollar}P NMRS) was used as a non-invasive probe of forearm muscle metabolism in three studies of healthy men and women. Specific objectives of the studies were to: (1) observe the changes in high energy phosphates and intracellular pH in muscle, during a ramp exercise protocol, (2) study the effect of endurance training on muscle metabolism and evaluate the utility of the forearm ramp test as a means to assess muscle oxidative capacity, and (3) describe the kinetics of phosphocreatine (PCr) and inorganic phosphate (Pi) metabolism during the on and off transient response to moderate …
Mucus-Secreting Cells Of The Colon In Health And Disease, Deena Patricia Rodney
Mucus-Secreting Cells Of The Colon In Health And Disease, Deena Patricia Rodney
Digitized Theses
Two morphologically distinct mucous cell types have been described in the ascending colon of rat and man. These include the goblet cells and non-goblet mucous (NGM) cells. The latter are known in the rat as "deep crypt secretory" (DCS) cells.;The purpose of this study was to examine various aspects of these NGM cells, including the histochemical nature of the rat DCS cell and human NGM cells. In addition, the reactions of the NGM cells were studied and compared to those of the goblet cells in an experimental model of colitis and in human IBD. A range of mammalian species, classed …
Studies Of Cis- Andtrans-Acting Genetic Elements In The Genome Of Minute Virus Of Mice, Ralph Salvino
Studies Of Cis- Andtrans-Acting Genetic Elements In The Genome Of Minute Virus Of Mice, Ralph Salvino
Digitized Theses
Studies presented in this thesis involve the identification and/or further characterization of cis-acting and trans-acting genetic elements required for minute virus of mice (MVM) DNA replication and gene expression. Plasmids with mutations introduced into the viral genome within the full length infectious plasmid pMM984 were transfected into murine A9 and primate COS-7 cells and viral DNA replication and gene expression were assessed using in vivo transient DNA replication and chloramphenicol acetyl transferase expression assays.;Results indicated that the nonstructural gene product NS-1 is a trans-acting protein that is required for the excision and replication of the viral genome and for capsid …
The Effects Of Gastrin Releasing Peptide In Fetal Sheep, Pregnant Sheep And Non Pregnant Sheep, Pamela Elizabeth Houghton
The Effects Of Gastrin Releasing Peptide In Fetal Sheep, Pregnant Sheep And Non Pregnant Sheep, Pamela Elizabeth Houghton
Digitized Theses
These studies examined the hypothesis that GRP stimulates insulin release from the endocrine pancreas of ovine fetuses. This could occur due to the action of GRP directly within the fetal compartment or due to indirect effects of GRP on glucose and insulin concentrations in the maternal compartment which in turn influences the availability of glucose for transplacental transfer to the fetus and hence produce alterations in fetal insulin release.;The studies performed provided the following results: (1) IR-GRP was detectable in nerves of the GI tract and in the systemic circulation but not in the pancreas of fetal and adult sheep; …
The Organization Of The Maize Photosystem Ii Light-Harvesting Apparatus Under Normal And Chilling Conditions, Douglas A. Campbell
The Organization Of The Maize Photosystem Ii Light-Harvesting Apparatus Under Normal And Chilling Conditions, Douglas A. Campbell
Digitized Theses
The maize light harvesting system is structurally and functionally perturbed by chilling stress, with alterations in fluorescence parameters and protein processing. The molecular basis for these changes was investigated through biochemical analysis of the photosystem II-associated light-harvesting complexes (LHC II) of maize mesophyll thylakoids.;LHC II complexes from thylakoids were separated into three populations by mildly-denaturing electrophoresis. LHC II-1 contains four polypeptides and is equivalent to the oligomeric LHC IIb complex of Thornber et al. (1988). A less abundant oligomeric band, LHC II-2, contains a subset of the LHC IIb polypeptides, along with the LHC IIa complex (CP 29). The LHC …
Biochemical And Morphological Characterization Of Cytoplasmic Particles From Avian Reticulocytes, Timothy W. Blaker
Biochemical And Morphological Characterization Of Cytoplasmic Particles From Avian Reticulocytes, Timothy W. Blaker
Digitized Theses
Ferritin can be isolated from quail reticulocyte lysates using a rapid two-step purification method that combines heat denaturation and proteinase-K treatments to produce high yields of pure, undegraded ferritin. Ferritin remains in the supernatant of heat-denatured samples, and subsequent treatment with proteinase-K eliminates non-ferritin proteins that remain in the supernatant as well as non-ferritin proteins that are found in association with ferritin.;Ferritin is a heat shock protein of quail reticulocytes. Its synthesis in heat-shocked cells is 3-5 times greater than in control cells. Ferritin subunits synthesized in response to heat shock consist of isoforms that are identical in size and …
Myosin Transformation In Thyrotoxic Rat Soleus Muscle, Margaret Mary Sopper
Myosin Transformation In Thyrotoxic Rat Soleus Muscle, Margaret Mary Sopper
Digitized Theses
Male Sprague-Dawley rats were injected with 300{dollar}\mu{dollar}g/kg body weight of Triiodo-L-thyronine (T{dollar}\sb3{dollar}) and L-thyroxine (T{dollar}\sb4{dollar}) on alternate days over a 28-day treatment period. Thyrotoxicosis was confirmed by increased serum T{dollar}\sb3{dollar} levels and a pronounced ventricular hypertrophy (p {dollar}\le{dollar} 0.05 after 5 days). The effects of thyroid hormone on isometric contractile properties of the slow-twitch soleus muscle were studied in situ after 2, 5, 7, 15, 21 or 28 days. Time to peak tension (TPT) and one half relaxation time (1/2 RT) were significantly reduced after 5 days (T-5, p {dollar}\le{dollar} 0.05) and reached 56.7% and 51.1% of age-matched control values …
Structure/Function Studies Of Trypanosome Variant Surface Glycoproteins, Vern Bruce Carruthers
Structure/Function Studies Of Trypanosome Variant Surface Glycoproteins, Vern Bruce Carruthers
Digitized Theses
Antigenic variation is manifested by many prominent infectious organisms in adaptive response to host immunity. However, polymorphism in antigenic structure is often limited by the necessity to maintain functionality of the antigen. It follows that it may be possible to design molecularly defined vaccines capable of accounting for variable antigenic phenotype. For this reason, the focus of the present thesis was to develop a model system using trypanosome variant surface glycoprotein (VSG) for examining the effects of amino acid sequence variation on the specificity of antigenic determinants.;In order to assess the suitability for a model system of four VSGs (isoVAT …
Studies On The In Vitro Transposition Of Bacteriophage Mu Dna, Michael Gordon Surette
Studies On The In Vitro Transposition Of Bacteriophage Mu Dna, Michael Gordon Surette
Digitized Theses
The early steps in the transposition of Mu DNA have been examined in vitro using purified Mu A, Mu B and E. coli HU proteins, a mini-Mu donor plasmid and target DNA. Two stable protein-DNA complexes, or transpososomes, have been characterized. Type 1 complex formation requires a supercoiled mini-Mu donor plasmid, Mu A and HU protein. In the Type 1 complex the two ends of Mu are held together, creating two independent topological domains; a supercoiled Mu domain and a relaxed vector domain (due to nicking at the Mu ends). In the presence of Mu B protein, ATP, and target …
Food Limitation And The Adaptive Significance Of Clutch Size In American Coots (Fulica Americana), Todd William Arnold
Food Limitation And The Adaptive Significance Of Clutch Size In American Coots (Fulica Americana), Todd William Arnold
Digitized Theses
For many species of birds, egg formation costs are considered important constraints on timing of breeding, clutch size, and egg size. For American Coots (Fulica americana), body reserves and current food availability are both thought to affect these aspects of reproduction. In order to test the egg formation hypothesis, I conducted numerous observational and manipulative experiments on wild, free-ranging American Coots. Clutch size declined with laying date in five out of six years, contrary to seasonal patterns of food availability in prairie wetlands. Clutch size increased during two of three years in response to supplemental feeding. Laying date was only …
Growth Temperature Effects On Photosynthesis And Photoinhibition Of Spinach (Spinacia Oleracea L), Steven Ray Boese
Growth Temperature Effects On Photosynthesis And Photoinhibition Of Spinach (Spinacia Oleracea L), Steven Ray Boese
Digitized Theses
Spinacea oleracea L. cv Savoy was utilized to determine the effects of growth temperature and temperature shifts after leaf expansion on growth, photosynthesis and photoinhibition.;Growth was slowed at 5{dollar}\sp\circ{dollar}C with the second leaves reaching full expansion at 92 days after planting compared to 32 days for 16{dollar}\sp\circ{dollar}C grown plants. Growth at 5{dollar}\sp\circ{dollar}C compared to 16{dollar}\sp\circ{dollar}C resulted in a 2 to 3 fold increases in leaf area, dry weight per area, and leaf thickness of fully expanded leaves. Further, growth at 5{dollar}\sp\circ{dollar}C resulted in an increase from 2 to 3 palisade layers and an increase in the freezing tolerance from {dollar}-2\sp\circ{dollar}C …