851 resultados para protein structure and folding
Resumo:
This thesis investigates two cases of Christian churches, which as a part of their mission seek to accommodate people who would otherwise not be interested in church. One of these communities consider themselves a part of the global 'emerging church' movement, and the other does not. I argue that both communities are employing what I call 'de-compartmentalization' strategy in order to adopt a pragmatic relationship with social and political issues. Furthermore I discuss the case of the emerging church community as an example of 'paraliminal community '; a concept I develop from the work of Victor Turner and Arnold van Gennep.
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Growth stimulation of Avena coleoptile tissue by indoleacetic acid (IAA) and fusicoccin (FC) was compared by measuring both their influence on RNA and protein synthesis during IAA or FC stimulated growth. FC stimulated growth more than IAA during the initial four hour exposure, after which the growth rate gradually declined to the control rate. FC, but not IAA, increased the uptake of 3H-Ieucine into tissue and the specific radioactivity of extracted protein. Cycloheximide inhibited the incorporation of 3H-Ieucine into protein by approximately 60% to 70% in all cases. In the presence of cycloheximide 3H-radioactivity accumulated in FC-treated tissue, whereas IAA did not seem to influence 3H-accumulation. These results suggest that FC stimulated leucine uptake into the tissue and that increased specific activity of coleoptile protein is due to increased leucine uptake, not an increased rate of protein synthesis. There was no measurable influence of IAA and/or FC on RNA and protein synthesis during the initial hours of a growth stimulation. Inhibitors of RNA and protein synthesis, actinomycin D and cycloheximide, respectively, severely inhibited IAA enhanced growth but only partially inhibited FC stimulated growth. The data are consistent with suggestions that a rapidly turning over protein participates in IAA stimulated growth, and that a continual synthesis of RNA and proteins is an absolute requirement for a long term growth response to IAA. On the contrary, FC-stimulated growth exhibited less dependency on the transcription and translation processes. The data are consistent with proposals suggesting different sites of action for FC and IAA stimulated growth. l?hen compared to CO2-free air, CO2 at 300 ppm had no significant influence on coleoptile growth and protein synthesis in the presence or absence of lAA or FC. Also, I mM malate, pH 6.0 did not influence growth of coleoptiles in the presence or absence of lAA. This result was obtained despite reports indicating that 300 ppm CO2 or I mM malate stimulates growth and protein synthesis. This lack of difference between CO2-treated and untreated tissue could indicate either that the interstitial space CO2 concentration is not actually different in the two treatments due to significant endogenous respiratory CO2 or else the data would suggest a very loose coupling between dark CO2 fixation and growth. IAA stimulated the in vivo fixation of 14c-bicarbonate (NaHI4c03) by about 25% and the addition of cycloheximide caused an inhibition of bicarbonate fixation within 30 min. Cycloheximide has also been reported to inhibit IAA-stimulated H+ excretion. These data are consistent with the acid growth theory and suggest that lAA stimulated growth involves dark CO2 fixation. The roles of dark CO2 fixation in lAA-stimulated growth are discussed.
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In the past ten years, many researchers have focussed their attention on parasites regarding the role they may play in causing variations in male secondary sexual traits and subsequent effects on female choice. Male age has also been suggested to be an important factor in female choice if old age reflects superior genes. This study investigated the effects that gregarine gut parasites, age, and diet have on the calling and mating behaviour of the male Texas field cricket, Gryllus integer. Male calling songs were recorded in the laboratory using a Digital Signal Processing Network. The song parameters measured were: pulse rate, pulse width, burst duration, pulses per burst, interburst interval, and percent missing pulses. The effects of parasite load and age on the various calling song parameters was investigated in crickets that were fed two different diets varying in nutritional quality. None of the calling song parameters were affected by either parasite load or age in either diet grou p. Courtship behaviour was ob served and recorded using an Eventlog recorder on an IBM computer in the laboratory. Females mated equally with paras(tized and unparasitized males and with old and young males The total duration and proportion of time spent performing each of 9 courtship displays were recorded for males on each diet. Only one display was affected by parasite load. Highly parasitized males fed the nutritionally inferior diet juddered for a proportionately shorter time than males with low parasite loads. Also, older males performed juddering and shaking antennae proportionally longer and juddering and raising wings for longer durations than younger males. Males that successfully mated were observed for performance of 8 post-copulatory guarding behaviour displays. None of the guarding behaviours were affected by parasite load. However, one display was affected by age, with older males performing guard turning for shorter durations than younger males. Results are discuss,ed in terms of the influence of parasites and age on female choice.
Resumo:
Polyglutamine is a naturally occurring peptide found within several proteins in neuronal cells of the brain, and its aggregation has been implicated in several neurodegenerative diseases, including Huntington's disease. The resulting aggregates have been demonstrated to possess ~-sheet structure, and aggregation has been shown to start with a single misfolded peptide. The current project sought to computationally examine the structural tendencies of three mutant poly glutamine peptides that were studied experimentally, and found to aggregate with varying efficiencies. Low-energy structures were generated for each peptide by simulated annealing, and were analyzed quantitatively by various geometry- and energy-based methods. According to the results, the experimentally-observed inhibition of aggregation appears to be due to localized conformational restraint placed on the peptide backbone by inserted prolines, which in tum confines the peptide to native coil structure, discouraging transition towards the ~sheet structure required for aggregation. Such knowledge could prove quite useful to the design of future treatments for Huntington's and other related diseases.
Resumo:
The present thesis describes syntheses, structural studies, and catalytic reactivity of new non-classical silane complexes of ruthenium and iron. The ruthenium complexes CpRu(PPri3)CI(T]2-HSiR3) (1) (SiR3 = SiCh (a), SiClzMe (b), SiCIMe2 (c), SiH2Ph (d), SiMe2Ph (e» were prepared by reactions of the new unsaturated complex CpRu(PPri3)CI with silanes. According to NMR studies and X-ray analyses, the complexes la-c exhibit unusual simultaneous Si··· H and Si··· CI-Ru interactions. The complex CpRu(PPri3)CI was also used for the preparation of the first examples of late transition metal agostic silylamido complexes CpRu(PPri3)(N(T]2-HSiMe2)R) (2) (R= Ar or But), which were characterized by NMR spectroscopy. The iron complexes CpFe(PMePri2)H2(SiR3) (3) (SiR3 = SiCh (a), SiClzMe (b), SiCIMe2 (c), SiH2Ph (d), SiMe2Ph (e» were synthesized by the reaction of the new borohydride iron complex CpFe(PMePri2)(B~) with silanes in the presence NEt3. The complexes 3 exhibit unprecedented two simultaneous and equivalent Si··· H interactions, which was confirmed by X-ray analyses and DFT calculations. A series of cationic ruthenium complexes [CpRu(PR3)(CH3CN)(112-HSiR'3)]BAF (PR3 = PPri 3 (4), PPh3 (5); SiR'3 = SiCh (a), SiClzMe (b), SiClMe2 (c), SiH2Ph (d), SiMe2Ph (e» was obtained by substitution of one of the labile acetonitrile ligands in [CpRu(PR3)(CH3CNh]BAF with sHanes. Analogous complexes [TpRu(PR3)(CH3CN)(T]2 -HSiR' 3)]BAF (5) were obtained by the reaction of TpRu(PR3)(CH3CN)CI with LiBAF in the presence of silanes. The complexes 4-5 were characterized by NMR spectroscopy, and the observed coupling constants J(Si-H) allowed us to estimate the extent of Si-H bond activation in these compounds. The catalytic activity in hydrosilylation reactions of all of the above complexes was examined. The most promising results were achieved with the cationic ruthenium precatalyst [CpRu(PPri3)(CH3CN)2t (6). Complex 6 shows good to excellent catalytic activity in the hydrosilylation of carbonyls, dehydrogenative coupling of silanes with alcohols, amines, acids, and reduction of acid chlorides. We also discovered very selective reduction of nitriles and pyridines into the corresponding N-silyl imines and l,4-dihydropyridines, respectively, at room temperature with the possibility of catalyst recycling. These chemoselective catalytic methods have no analogues in the literature. The reactions were proposed to proceed via an ionic mechanism with intermediate formation of the silane a-complexes 4.
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This paper studies vertical R&D spillovers between upstream and downstream firms. The model incorporates two vertically related industries, with horizontal spillovers within each industry and vertical spillovers between the two industries. Four types of R&D cooperation are studied : no cooperation, horizontal cooperation, vertical cooperation, and simultaneous horizontal and vertical cooperation. Vertical spillovers always increase R&D and welfare, while horizontal spillovers may increase or decrease them. The comparison of cooperative settings in terms of R&D shows that no setting uniformly dominates the others. Which type of cooperation yields more R&D depends on horizontal and vertical spillovers, and market structure. The ranking of cooperative structures hinges on the signs and magnitudes of three competitive externalities (vertical, horizontal, and diagonal) which capture the effect of the R&D of a firm on the profits of other firms. One of the basic results of the strategic investment literature is that cooperation between competitors increases (decreases) R&D when horizontal spillovers are high (low); the model shows that this result does not necessarily hold when vertical spillovers and vertical cooperation are taken into account. The paper proposes a theory of innovation and market structure, showing that the relation between innovation and competition depends on horizontal spillovers, vertical spillovers, and cooperative settings. The private incentives for R&D cooperation are addressed. It is found that buyers and sellers have divergent interests regarding the choice of cooperative settings and that spillovers increase the likelihood of the emergence of cooperation in a decentralized equilibrium.
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In an economy where cash can be stored costlessly (in nominal terms), the nominal interest rate is bounded below by zero. This paper derives the implications of this nonnegativity constraint for the term structure and shows that it induces a nonlinear and convex relation between short- and long-term interest rates. As a result, the long-term rate responds asymmetrically to changes in the short-term rate, and by less than predicted by a benchmark linear model. In particular, a decrease in the short-term rate leads to a decrease in the long-term rate that is smaller in magnitude than the increase in the long-term rate associated with an increase in the short-term rate of the same size. Up to the extent that monetary policy acts by affecting long-term rates through the term structure, its power is considerably reduced at low interest rates. The empirical predictions of the model are examined using data from Japan.
Resumo:
Des études antérieures ont démontré que le métabolisme de la rétine, son apport sanguin et sa consommation de l'oxygène sont plus élevés dans le noir (Riva C.E. et al. 1983, Wang L. et al. 1996, Tam B.M. and Moritz O.L. 2007). Les stimuli physiologiques jouent supposément un rôle important dans le développement des différents systèmes nerveux (Arthur W. Spira, David Parkinson 1991). La privation de la rétine de son stimulus physiologique, la lumière, est un moyen valable de démontrer la validité de ce concept. D'autres études ont affirmé que les injections de dichlorure de paraquat dans la cavité vitréenne causent une sévère rétinopathie (Rétinopathie induite par paraquat: RIP). Cette rétinopathie est provoquée par les dérivés réactifs de l'oxygène (DRO) générés par le paraquat (Cingolani C. et al. 2006, Lu L. et al. 2006). Le but de notre premier projet (''Dark rearing project'') était de déterminer si les conséquences nocives de l'hyperoxie postnatale chez les rats albinos SD pourraient être amoindries en élevant une portée de rats au noir. Nos résultats suggèrent qu'une augmentation du métabolisme de la rétine causée par la déprivation de lumière chez les ratons, pourrait protéger ou masquer certains effets néfastes de l'hyperoxie postnatale. Le but de notre deuxième étude (''Paraquat project'') était d'examiner les possibles points de similitude entre RIP et d'autres modèles de rétinopathies oxydatives étudiés présentement par notre équipe, à savoir: Rétinopathie induite par l'oxygène (RIO) et Rétinopathie induite par la lumière (RIL). Nos résultats suggèrent que l'injection de dichlorure de paraquat dans la cavité vitréenne cause des changements sévères de la fonction de la rétine, tandis que sa structure semble intacte. La sévérité de ces changements dépend inversement de la maturité de la rétine au moment de l'injection.
Resumo:
Thèse diffusée initialement dans le cadre d'un projet pilote des Presses de l'Université de Montréal/Centre d'édition numérique UdeM (1997-2008) avec l'autorisation de l'auteur.
Resumo:
The basic objective of the present study has been to observe the process and pattern of employment diversification among the rural women workers in Ernakulam district. The evidences are that the women workers in the rural areas of the state are being increasingly diversified into the tertiary sector. The clear cut evidence for the fact that in Kerala non-agricultural employment of rural women is increasing with more and more of them getting diversified into the tertiary sector. The women get more self esteem and recognition in terms of the work being done by them. In the urban areas of the state as a poverty eradicating measure the Kerala government has already introduced a new scheme under the banner of Kudumbasree. Another fact noticed in the study that the sectoral shift of women workers has posed a grave problem to the agricultural sector. The reluctance of workers to do manual jobs on land and the prevalence of high wages among the agricultural labours has left many a cultivable area fallow or has induced farmers to shift to less labour –intensive crops. The situation is expected to worsen in future as even the high wages fail to attract the young generation to this sector. To conclude the study has fulfilled all its objectives, viz; highlighting the rural employment structure in Kerala, examining the process, pattern, determinants and consequences of diversification among rural women workers in the sample villages. Being the first of its kind at the micro level in the state it contributes to the available literature in the area enriching the database that is crucially lacking for devising projects at the village and block-level. There exists ample scope for future research of similar nature in an urban background where the secondary data-sources are hinding towards a reversal of trends from non-agriculture to agriculture.
Resumo:
The main objective of the present study is to model the gravity fields in terms of lithospheric structure below the western continental margin of India (WCMI) identify zones of crustal mass anomalies and attempt to infer the location of Ocean Continent transition in the Arabian Sea. In this study, the area starting from the western shield margin to the region covering the deep oceanic parts of the Arabian Sea which is bounded by Carlsberg and Cerg and Central Indian ridges in the south, eastern part of the Indus Cone in the west and falling between 630E and 800E longitudes, and 50N - 240N latitudes has been considered. The vast amount of seismic reflection and refraction data in the form of crustal velocities, basement configuration and crustal thicknesses available for the west coast as well as the eastern Arabian Sea has been utilized for this purpose
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The changes occuring to cashew kernels during storage at two humidity levels - 80% to 20% with respect to organoleptic characteristics, protein content, carbohydrate content, oil content, iodine and peroxide values were studied. From the present study it is concluded that organoleptic characteristics of cashew kernels deteriorates with increase in humidity. Decrease in protein and carbohydrate content of stored cashew kernel is dependent on humidity. Humidity increased oxidative rancidification.
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It examine the aspects of Madhya Pradesh’s industrial structure which throw light on the development, viability and the efficiency of not only the over all industrial sector but also some of the selected industries of the state. The major objectives of are to examine the nature and characteristics of economic backwardness in Madhya Pradesh in an inter-state comparative framework and to analyse the pace and pattern of industrial growth in Madhya Pradesh against the backdrop of liberalization. To explore the industrial structure of Madhya Pradesh using the major structural ratios and industry mix. This study has underlined some structural as well as region specific constraints to the accelerated growth of the manufacturing industry in Madhya Pradesh. The industrial structure of Madhya Pradesh is concentrated and lop-sided. This is evidenced by the dominancy of single industry, basic metal and alloys. A diversified industrial structure is essential for promoting interdependent growth of the manufacturing industry based on the inter-industry linkages and agglomeration. The thesis gives a broad spectrum of regional disparities in development and evidence for Madhya Pradesh’s backwardness also portrayed and reflects the changing industrial structure of the state.
Resumo:
In natural rubber/high styrene resin microcellular sheets, part of natural rubber was replaced by latex reclaim prepared from waste latex products. The mechanical properties and cell structure of the products were evaluated. It was found that latex reclaim can replace about 30% of natural rubber without affecting the technical properties of the microcellular sheets.
Resumo:
Cast Ai-Si alloys are widely used in the automotive, aerospace and general engineering industries due to their excellent combination of properties such as good castability, low coefficient of thermal expansion, high strength-to-weight ratio and good corrosion resistance. The present investigation is on the influence of alloying additions on the structure and properties of Ai-7Si-0.3Mg alloy. The primary objective of this present investigation is to study these beneficial effects of calcium on the structure and properties of Ai-7Si-0.3Mg-xFe alloys. The second objective of this work is to study the effects of Mn,Be and Sr addition as Fe neutralizers and also to study the interaction of Mn,Be,Sr and Ca in Ai-7Si-0.3Mg-xFe alloys. In this study the duel beneficial effects of Ca viz;modification and Fe-neutralization, comparison of the effects of Ca and Sr with common Fe neutralizers. The casting have been characterized with respect to their microstructure, %porosity and electrical conductivity, solidification behaviour and mechanical properties. One of the interesting observations in the present work is that a low level of calcium reduces the porosity compared to the untreated alloy. However higher level of calcium addition lead to higher porosity in the casting. An empirical analysis carried out for comparing the results of the present work with those of the other researchers on the effect of increasing iron content on UTS and % elongation of Ai-Si-Mg and Ai-Si-Cu alloys has shown a linear and an inverse first order polynomial relationships respectively.