The physiological ecology of five coastal species has been examined with respect to temperature and its effect on survival and distribution. The aims of the study have been to establish whether any direct correlation exists between distribution and the responses of the plants to temperature at different stages in the life cycle. The species Tinder consideration were the northern Ligusticum scoticum and Mertensia maritima and the southern Crithmum maritimum, Limonium binervosum and Glaucium flavum. Highest germination percentages for each species were found at temperatures close to those associated with the season favourable for germination in the natural habitat. Northern species had higher temperature requirements than the southern, corresponding to spring/ summer and autumn or spring germination respectively. Root respiration, measured as oxygen uptake, was found to be twice as great in the northern Ligusticum and Mertensia as in the southern Crithmum and Limonium over a range of experimental temperatures. This varied to some extent with time and temperature of pretreatment. The single experiment on the southern Glauci.um showed rates similar to those of the northern species. Arrhenius plots' of respiration data for the northern species showed a break in gradient at the upper end of the experimental temperature range which correlated well with apparently limiting July mean temperatures from the distribution maps. The southern Crithmum showed a break at lower temperature range close to the limiting January mean temperature. The response of Limonium to experimental temperature depended on the pretreatment; upper range breaks were shown after low pretreatment temperatures, and lower range breaks after higher pretreatment temperatures. The single experiment on Glaucium gave a straight line Arrhenius plot. Carbohydrate analyses of the same pretreated plants yielded additional information relevant to the survival and thus to the distribution in relation to temperature. The southern Crithmum had the highest starch content at all temperatures while the northern Ligusticum and Mertensia had less. Ratios of soluble sugar to starch were greatest in the northern species, possibly reflecting displacement of the equilibrium from starch to soluble sugar at lower temperatures. Overall a connection has been demonstrated between the direct effects of temperature on the plants and the limitation of distribution by temperature. This is clearest for the two northern species, Ligusticum scoticum and Mertensia maritima, less definite for the southern Crithmum maritimiim, and only suggested for Limonium binervosum with its apparently less simple temperature responses. Glaucium flavum appears anomalous and requires further study.

Small brightenings called x-ray bright points (Golub et al, 1974) occur in the solar corona. They are observed with the soft x-ray telescope on Skylab to be approximately 22 Mm in diameter with a brighter inner core of width 4-7 Mm although with the Normal Incidence X-ray Telescope their dimensions are observed to be typically 6 Mm x 9 Mm. By comparison with magnetograms of the photosphere it has been noticed recently that there is a high correlation between the occurrence of x-ray bright points and the mutual reduction of flux between two opposite polarity magnetic fragments. These fragments are originally unconnected magnetically, but move towards each other and simultaneously lose equal amounts of flux (cancel): they are called cancelling magnetic features (Martin et al, 1984). The observations relating to these features were reviewed by Priest et al. (1994) who suggested that they naturally evolve through three phases: the pre-interaction, interaction and cancellation phases. From this evidence qualitative pictures of the magnetic field structure for an x-ray bright point and associated cancelling magnetic feature were established. The aim of this thesis has been to build on the ideas of Priest et al. (1994) to produce a detailed theoretical model of an x-ray bright point and a cancelling magnetic feature. The magnetic field structures are estimated, and the position and lifetime of the bright point are calculated, as is the total amount of energy released during the bright point. This work is also extended to study more complex cancelling configurations representing the main basic types of cancelling magnetic feature. The results of these models determine the factors that affect the lifetime and position of a bright point and indicate which types of cancelling magnetic features are most likely to produce bright points that are long-lived, lie directly above the cancellation site and occur simultaneously with the cancellation phase. The complex structure of a bright point cannot be explained from the above two-dimensional models: thus two recently observed bright points were studied to see if the above model could be extended into three dimensions to explain the structure seen in soft x-ray images. The available observational data was used and leads to reasonable explanations for the complex shapes of both bright points. Finally, a more realistic model for the overlying field was set up involving a model of the field above a supergranule cell field with fragments of finite width. The interaction of an ephemeral region within this field was then studied and led to five different scenarios. The results obtained reaffirmed those found in the previous simpler models and suggest where bright points may appear in a cell relative to the cancelling magnetic feature and for how long the bright points might last. Predictions for the lifetimes of cancelling magnetic features are also made, indicating when the cancelling magnetic feature occurs relative to the bright point.

Thesis (Ph. D.)--University of Missouri--Columbia, 1999. / "May 1999." Typescript. Vita. Includes bibliographical references (leaves 108-124). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Vita. "May 2005" Includes bibliographical references.

Made available in DSpace on 2015-12-06T23:44:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2006 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A pilocarpina é um agonista colinérgico que, quando injetada em altas doses (i.p.) a ratos, reproduz as principais características da epilepsia do lobo temporal (ELT) humana. O animal exibe diferentes padrões de comportamentos, incluindo status epilepticus (fase aguda), normalização comportamental (fase latente) e finalmente crises espontâneas e recorrentes (fase crônica). Os objetivos desse estudo foram analisar por microdiálise e HPLC a concentração de ATP e seus metabólitos na formação hipocampal de ratos que se encontram nas fases aguda e crônica do modelo experimental de ELT induzida por pilocarpina, e avaliar através de imunoblot e imuno-histoquímica, os receptores P2X2,4,7 na formação hipocampal desses animais, incluindo o grupo latente. O procedimento de microdiálise foi aplicado para determinação da concentração de purinas liberadas durante o status epilepticus (SE) em amostras coletadas nos seguintes tempos: Basal (3 amostras antes de qualquer tratamento), após a administração de metilescopolamina (usada para minimizar os efeitos periféricos da pilocarpina) e 30 min. 1H, 2H, 3H e 4H após a aplicação da pilocarpina. Os animais crônicos foram estudados nos períodos interictal e ictal. As amostras foram analisadas por HPLC com detecção por fluorescência. Animais de três grupos experimentais (G12H; GLat; GCro) e respectivos controles, foram empregados para o estudo dos receptores P2X2,4,7, através de imunoblot e imuno-histoquímica. O imunoblot foi revelado por quimiluminescência. A imuno-histoquímica foi feita com cortes fixados e flutuantes em tampão, usando anticorpo biotinilado e kit ABC e revelação com diaminobenzidina. O estudo bioquímico revelou um aumento de ADP, AMP e adenosina durante o SE. Na fase crônica, evidenciou-se uma redução de todas as purinas no período interictal, e um aumento das mesmas no período ictal, sendo significante para o ATP e adenosina. Em relação aos receptores estudados por imuno-histoquímica e imunoblot, observou-se uma intensa redução dos P2X4 versus CT no período crônico (35%, p<0.001, ANOVA), um aumento do P2X7 nas fases aguda e crônica (G12H: 20%, p<0,05; GCRO: 18% p<0,05, ANOVA).Com base nos resultados, conclui-se que o metabolismo das purinas está alterado na fisiopatologia da ELT induzida por pilocarpina, por exemplo, na fase aguda o aumento na concentração de ADP, AMP e de adenosina, pode estar refletindo um aumento na taxa metabólica do ATP pelas ectonucleotidases, como um mecanismo compensatório inibitório. No entanto, o ATP antes de ser metabolizado pode estar ativando receptores P2X7, e exercendo um papel importante na citotoxicidade. Já na fase crônica, a redução das purinas, infere principalmente um comprometimento na atividade inibitória mediada pela adenosina, que por sua vez pode facilitar a susceptibilidade às crises epilépticas. / Pilocarpine, a muscarinic cholinergic agonist when inject at high doses (i.p.) in rats, reproduces the main characteristics of Human Temporal Lobe Epilepsy (TLE). The animal exhibits different patterns of behavior, including status epilepticus (acute phase), electrophysiological and behavioral normalization (latent phase) and spontaneous recurrent seizures (chronic phase). The objectives of this study were to analyze by means of microdyalysis and HPLC, the concentration of ATP and its metabolites ADP, AMP and adenosine in the hippocampal formation of rats during the acute and chronic phases of pilocarpine model, and evaluating by western blotting and immunohistochemistry, the receptors P2X2,4,7 in the hippocampal formation of these animals. The microdyalysis procedure used to determine the purines concentration in the acute period, was taken according to the following periods of time: Basal (three samples before treatment onset), after methylscopolamine injection (used in order to minimize the peripheral effects of pilocarpine) and 30 min. 1h, 2h, 3h and 4h after pilocarpine injection. Chronic animals were studied during the interictal and ictal period. The samples were analyzed by a fluorescence detector coupled to HPLC. Animals from three different experimental groups (Group 12h = G 12h, Latent Group = G Lat, Chronic Group = G Cro) and their respective controls were utilized to analyze the purinergic receptors P2X2,4,7, by means of western blotting and immunohistochemistry. The immunohistochemistry was achieved with fixated slices floating on buffer solution, using biotinylated antibody, ABC kit and development with diaminobenzidine. The biochemical study revealed an increase of ADP, AMP and adenosine concentrations during the SE. In contrast, a reduction of all purines was detected in the hippocampal formation during the interictal period of chronic rats. Rats studied during the ictal phase, exhibited high concentrations of ATP and adenosine. The immunohistochemistry and western blotting analysis showed a great reduction of P2X4, versus CT in the chronic period (35%, p<0.001, ANOVA), and an increase of P2X7, in the acute and chronic phases (G12H: 20%, p<0.05; GCRO: 18% p<0.05, ANOVA). According to these findings, we can conclude that the metabolism of purines is altered in the hippocampal formation of rats in pilocarpine-induced epilepsy. In the acute phase, the increase of ATP metabolites may reflect an increase in the metabolism rates of ATP by the ectonucleotidases, possibly as a compensatory inhibitory mechanism. On the other hand, before ATP is hydrolyzed, it may activate P2X7 purinoceptor, and consequently, intensify hyperexcitability and cytotoxicity cascades. A decrease in all purines analyzed in the chronic phase could suggest an energy metabolism dysfunction in the epileptic hippocampus. The decrease in the adenosine concentrations might facilitate the onset of spontaneous and recurrent seizures. / BV UNIFESP: Teses e dissertações

The psychophysical experiments and numerical modelling reported in the present study are an investigation into the encoding of relative location of intensity changes in the human visual system. The study attempted, successfully, to explain some geometric illusions resulting from closely spaced image features ('crowding'), and determined the nature of information necessary for making judgments about the separation of intensity changes for different stimulus configurations. Experiments performed fell into two basic categories; those concerned with spatial interference, and studies of spatial interval judgments. The first set of experiments, studying spatial interference with relative localisation for intensity changes, was based on measurements made with stimuli composed of lowpass filtered bars and edges. The most successful model, which accounted for all of the data, was Watt and Morgan's (1984, 1985) MIRAGE; the results suggest that a good explanation of some geometric illusions can be derived using the principles of low-level vision. Spatial interference is strong evidence for combination of information across spatial scales, and the MIRAGE algorithm makes some highly accurate predictions. Relating the separation of image features is a fundamental task for the visual system, but there is no clear understanding of what information the system has available to perform this task. The second set of experiments explored the perception of separation, and precision of judgments of separation, for bars with a variety of orthoaxial contrast profiles. The data indicate that information is combined across spatial scales (as in MIRAGE) under certain circumstances in making separation judgments; this combination of information across scale occurs when the information on the scales combined is in agreement (ie. all scales have some task-related information), but when variance is added on coarser scales which is not relevant to the task, the system is capable of selecting the finest scales of filters available, and using only the information in the finest scale. This adaptive scale-selection process operates even at very brief exposure durations.

by Vincent, Wai-ip Law. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 128-134). / Abstract also in Chinese. / Chapter Chapter I. --- Literature Review / Chapter I.1. --- "Structure, functions and general physiology of equine sweat gland" / Chapter I.1.1. --- Ultrastructure of equine sweat gland --- p.1 / Chapter I.1.2. --- Functions and physiology of equine sweat gland --- p.3 / Chapter I.1.3. --- Experimental studies on equine sweat gland by functional approaches --- p.4 / Chapter I.1.4. --- Hormonal and neuronal regulation of sweat secretion in equidaes --- p.5 / Chapter I.1.5. --- Possible role(s) of extracellular ATP in equine sweat gland epithelia --- p.6 / Chapter I.1.6. --- Measurement of electrogenic anion secretion by short-circuit current (Isc) technique --- p.8 / Chapter I.2. --- Classification of purinergic receptors and its existence in biological systems / Chapter I.2.1. --- Functional classification of purinergic receptors --- p.13 / Chapter I.2.2. --- Basic structure of G-protein coupled P2Y receptors --- p.17 / Chapter I.2.3. --- Physiological function and significance of purinergic receptors --- p.20 / Chapter I.3. --- Objectives of study --- p.22 / Chapter Chapter II. --- Methods and Materials / Chapter II.l. --- Culture technique of the equine epithelial cells --- p.23 / Chapter II.2. --- Conventional short-circuit current (Isc) measurement technique / Chapter II.2.1. --- Introduction --- p.25 / Chapter II.2.2. --- Preparation of permeable supports and electrodes --- p.25 / Chapter II.2.3. --- Experimental set up and measurement of Isc --- p.28 / Chapter II.2.4. --- Measurement of Isc during experiment --- p.30 / Chapter II.3. --- Measurement of intracellular free calcium ( [Ca2+ ]ii) by microspectrofluorimetry / Chapter II.3.1. --- Preparation of cells --- p.31 / Chapter II.3.2. --- The set up and procedures for experiment --- p.31 / Chapter II.4. --- Simultaneous measurement of changes in [Ca2+ ]i and Isc / Chapter II.4.1. --- Experimental set up and manipulation --- p.35 / Chapter II.4.2. --- Other preparations before experiment --- p.37 / Chapter II.5. --- Material and solutions used for experiment / Chapter II.5.1. --- Culture media and enzyme --- p.40 / Chapter II.5.2. --- Chemicals and Drugs --- p.40 / Chapter II.5.3. --- Preparation of solution for experiments --- p.42 / Chapter II.6. --- Statistical analysis --- p.44 / Chapter Chapter III. --- Results / Chapter III.l. --- Effects of nucleotides on transepithelial ion transport / Chapter III.1.1. --- Basic electrophysiological properties of cultured equine sweat gland epithelia --- p.45 / Chapter III. 1.2. --- Short-circuit current (Isc) induced by nucleotides --- p.45 / Chapter III. 1.3. --- Identification of ion species responsible for the change in Isc --- p.50 / Chapter III. 1.4. --- Effects of chloride channels blockers on the UTP-induced Isc --- p.51 / Chapter III.2. --- Signal transduction mechanisms of P2Y-nucleotide receptors / Chapter III.2.1. --- The involvement of Gi-proteins --- p.56 / Chapter III.2.2. --- Effect of BAPTA on the increases in Isc induced by nucleotides --- p.58 / Chapter III.2.3. --- Study of P2Y-receptor mediated increase in [Ca2+]i --- p.62 / Chapter III.3. --- Characterization of the P2Y subtype(s) by cross desensitization experiments / Chapter III.3.1. --- Autologous desensitization experiments --- p.70 / Chapter III.3.2. --- Classical cross desensitization experiments --- p.70 / Chapter III.3.3. --- Characterization of the ATP-insensitive P2Y-receptor --- p.80 / Chapter III.3.4. --- Interaction between ATP and bradykinin --- p.87 / Chapter III.4. --- Simultaneous measurement of [Ca2+]i and Issc / Chapter III.4.1. --- Effect ofUDP and ADP --- p.89 / Chapter III.4.2. --- Correlation of Isc and [Ca2+]i --- p.92 / Chapter III.4.3. --- Cross desensitization experiments --- p.97 / Chapter III.5. --- Evidence of a [Ca2+]i-independent Isc-component induced by nucleotides / Chapter III.5.1. --- The time course of the ΔRf and ΔISC --- p.102 / Chapter III.5.2. --- Effect of ionomycin on the ΔISC and ΔRf induced by nucleotides --- p.110 / Chapter III.5.3. --- Effect of thapsigargin on the ΔISC and ΔRf induced by nucleotides --- p.110 / Chapter III.5.4. --- Effect of thapsigargin in nominal Ca2+-free solution --- p.115 / Chapter Chapter IV. --- Discussion / Chapter IV. 1. --- Role of extracellular nucleotides in epithelial tissues --- p.119 / Chapter IV.2. --- Characterization of an ATP-insensitive P2Y-nucleotide receptor --- p.120 / Chapter IV.3. --- Expression of the novel ATP-insensitive receptor on a functionally polarized epithelia --- p.122 / Chapter IV.4. --- Involvement of a [Ca2+]i -independent Isc induced by nucleotides --- p.124 / Chapter Chapter V. --- References --- p.128

PTEN (phosphatase and tensin homolog deleted on chromosome ten) is a potent tumor suppressor. PTEN’s tumor suppressor action is rooted in its phosphatase function on the lipid substrate phosphatidylinositol-(3,4,5)-trisphosphate (PI(3,4,5)P3). PTEN’s enzymatic activity is specific for the third position of the inositol headgroup. PI(3,4,5)P3 is a second messenger that is a part of the PI3K-Akt pathway, and its dysregulation leads to constitutively activated AKT. The result of AKT activation is cell cycle progression, motility, cell growth, and proliferation, and consequently, overaction leads to neoplastic growth and tumorigenesis. PTEN antagonizes this pathway by regulating PI(3,4,5)P3 population through its phosphatase activity which produces the lipid PI(4,5)P2 (phosphatidylinositol-(4,5)-bisphosphate). A result of PTEN’s function is that its activity must be localized at the PM (plasma membrane) since this is where its substrate resides. Additionally, the mole percent of the phosphoinositide family of lipids is small. From highest percent composition to lowest the phosphoinositide species in the PM rank as PI(4,5)P2 (~2%), PI(4)P (~1%), and PI(3,4,5)P3 (~0.02%). For PTEN to turn over its substrate, it must first translocate from the cytosol to the PM and then search through the plasma membrane for this rare but high in demand lipid. This is at the center of the scarcity paradox. This work explores how PTEN may overcome this paradox by using its multiple lipid binding domains to interact with multiple lipid partners to efficiently localize it toward a region with a high probability of having PI(3,4,5)P3. This hypothesis is tested using two kinetic methodologies. First, we use pre- steady state stopped-flow spectrometry to determine the rates that govern PTEN-lipid binding. Second, we use single-molecule total internal reflectance fluorescence (smTIRF) microscopy to resolve the diffusion coefficients and dwell times of bound PTEN on SLBs supported lipid bilayers (SLBs). We test PTEN against various lipid compositions to determine how the bilayer structure in addition to the chemistry of the lipid influences the enzyme’s binding. These compositions include PI(4,5)P2, PI phosphatidylinositol (PI), phosphatidylserine (PS), PI(4,5)P2/PI and PI(4,5)P2/PS. In addition to this kinetic work, we will also present a novel model membrane platform that takes advantage of a microfluidic device to develop lateral lipid gradients in SLBs. This microfluidic platform, in the future, will allow for the investigation of the dynamic behavior of proteins interacting with lipids but with a bilayer that has a structure recapitulating polarized membranes like in chemotaxing cells.

<p>Probably no group of organisms has been as important as bacteriophages when it comes to the understanding of fundamental biological processes like transcriptional control, DNA replication, site-specific recombination, e.t.c.</p><p>The work presented in this thesis is a contribution towards the complete understanding of these organisms. Two proteins, integrase, and Cox, which are important for the choice of the life mode of bacteriophage P2, are investigated. P2 is a temperate phage, i.e. it can either insert its DNA into the host chromosome (by site-specific recombination) and wait (lysogeny), or it can produce new progeny with the help of the host protein machinery and thereafter lyse the cell (lytic cycle). The integrase protein is necessary for the integration and excision of the phage genome. The Cox protein is involved as a directional factor in the site-specific recombination, where it stimulates excision and inhibits integration. It has been shown that the Cox protein also is important for the choice of the lytic cycle. The choice of life mode is regulated on a transcriptional level, where two mutually exclusive promoters direct whether the lytic cycle (Pe) or lysogeny (Pc) is chosen. The Cox pro-tein has been shown to repress the Pc promoter and thereby making tran-scription from the Pe promoter possible, leading to the lytic cycle. Further, the Cox protein can function as a transcriptional activator on the parasite phage, P4. P4 has gained the ability to adopt the P2 protein machinery to its own purposes.</p><p>In this work the importance of the native size for biologically active integrase and Cox proteins has been determined. Further, structure-function analyses of the two proteins have been performed with focus on the protein-protein interfaces. In addition it is shown that P2 Cox and the P2 relative Wphi Cox changes the DNA topology upon specific binding. From the obtained results a mechanism for P2 Cox-DNA interaction is discussed.</p><p>The results from this thesis can be used in the development of a gene delivery system based on the P2 site-specific recombination system.</p>

Probably no group of organisms has been as important as bacteriophages when it comes to the understanding of fundamental biological processes like transcriptional control, DNA replication, site-specific recombination, e.t.c. The work presented in this thesis is a contribution towards the complete understanding of these organisms. Two proteins, integrase, and Cox, which are important for the choice of the life mode of bacteriophage P2, are investigated. P2 is a temperate phage, i.e. it can either insert its DNA into the host chromosome (by site-specific recombination) and wait (lysogeny), or it can produce new progeny with the help of the host protein machinery and thereafter lyse the cell (lytic cycle). The integrase protein is necessary for the integration and excision of the phage genome. The Cox protein is involved as a directional factor in the site-specific recombination, where it stimulates excision and inhibits integration. It has been shown that the Cox protein also is important for the choice of the lytic cycle. The choice of life mode is regulated on a transcriptional level, where two mutually exclusive promoters direct whether the lytic cycle (Pe) or lysogeny (Pc) is chosen. The Cox pro-tein has been shown to repress the Pc promoter and thereby making tran-scription from the Pe promoter possible, leading to the lytic cycle. Further, the Cox protein can function as a transcriptional activator on the parasite phage, P4. P4 has gained the ability to adopt the P2 protein machinery to its own purposes. In this work the importance of the native size for biologically active integrase and Cox proteins has been determined. Further, structure-function analyses of the two proteins have been performed with focus on the protein-protein interfaces. In addition it is shown that P2 Cox and the P2 relative Wphi Cox changes the DNA topology upon specific binding. From the obtained results a mechanism for P2 Cox-DNA interaction is discussed. The results from this thesis can be used in the development of a gene delivery system based on the P2 site-specific recombination system.