Dissertations / Theses on the topic 'Stress adaptations'

Posttraumatic Stress Disorder (PTSD), the signature wound of the Iraq and Afghanistan wars, has caused veterans to face numerous and complex challenges within their intimate relationships post-deployment. Although other studies have explored the intimate relationships of veterans, the same level of research has not focused on OEF/OIF veterans from the standpoint of dyadic adaptation using the Dyadic Adaptation Scale (DAS). The purpose of this study was to explore the level of dyadic adaptation in intimate relationships of OEF/OIF veterans who self-reported PTSD and those who did not. More specifically, this study identified the factors that were related to the level of dyadic adaptation for this population. Participants were 126 OEF/OIF veterans who were enrolled in colleges and universities throughout the state of Iowa; provided basic background information in response to a demographics questionnaire; and completed the DAS to yield scores of the participants' dyadic adaptation within their intimate relationships, the Family Crisis Oriented Personal Evaluation Scales (F-COPES) that highlighted their levels of coping, and the Family Inventory of Life Events (FILE) that measured their life stressors within the last 12 months. The results of the correlation, MANOVA, ANOVA, and hierarchical regression analyses provided four major findings and implications. First, among participants with PTSD, DAS was correlated with tours of duty, FILE, F-COPES, and pharmacologic intervention, and among participants without PTSD, DAS was correlated with FILE. Second, the total dyadic adaptation scores for participating OEF/OIF veterans suggested an overall slight level of relationship dissatisfaction. Third, participants who self-reported PTSD had lower DAS total scores than participants who did not self-report PTSD. In addition, there was a significant difference on all four subscales (cohesion, satisfaction, consensus, and affectional expression) of the DAS between the two groups of participants. Fourth, in terms of participants who self-reported PTSD, tours of duty, types of relationships, and life stressors were the only variables that positively affected dyadic adaptation. In contrast, for participants who did not self-report PTSD, FILE was the only variable that affected the dyadic adaptation. These findings have important implications that highlight areas in which clinicians, educators, and individuals within the helping professions can join the Department of Veterans Affairs' initiatives to improve the reintegration of OEF/OIF veterans into their familiar roles post-deployment. Future research should explore the relationship norms pre-deployment and across relationship statutes, the identity of military intimate partners within treatment facilities, and the perceptions of treatment and dyadic adaptation after OEF/OIF veterans receive treatment in the community by civilian providers as compared to treatment in VA facilities.

Bacillus cereus est une bactérie à coloration de Gram positive capable de s'adapter à un grand nombre de stress tels que les bas pH ou les bas potentiels d'oxydo-réduction (Eh). Si certains des mécanismes d'adaptation de B. cereus à chacun de ces stress sont connus, les intéractions entre ces deux facteurs sur la physiologie bactérienne n'ont jamais été étudiés. Nous nous sommes donc intéressés à l'effet des variations de Eh sur la résistance au stress acide de B. cereus, aux adaptations métaboliques de B. cereus à pH acide et à l'intéraction de cette bactérie avec son environnement redox. Les résultats obtenus ont démontré, dans un premier temps, que la survie de B. cereus au choc acide était légèrement augmentée sous atmosphères à Eh réducteurs par rapport aux atmosphères à Eh oxydants. Nous avons également observé une réorientation majeure du métabolisme de B. cereus exposé à pH acide depuis la fermentation des acides mixtes vers la fermentation butanediolique. Cette réorientation joue vraisemblablement un rôle important dans la résistance au stress acide de B. cereus. Dans un second temps, nous avons étudié les intéractions de B. cereus avec son environnement redox et nous avons montré l'importance des groupements thiols exofaciaux dans l'activité réductrice de cette bactérie. L'ensemble de ces résultats permettent de mieux comprendre la physiologie de B. cereus confronté à un stress acide et aux variations de Eh et ouvre la voie à de nombreuses pistes de recherches novatrices
Bacillus cereus is a Gram positive bacterium able to adapt and survive to numerous stress, including acid stress or oxydo-reduction potential (Eh) variations. Some adaptations are documeted for each of these two stress. However, the interaction between Eh and pH on B. cereus physiology was never studied. Here, we focus on the impact of Eh variation on the acid resistance of B. cereus, on the metabolic adaptation of these bacteria under low pH and on the interaction of bacterial cells with their redox environement. Results obtained demonstrate that the acid survival of B. cereus was slighlty higher under reductive Eh than under oxdative Eh. Concerning acid adaptations, we observed a major metabolic adjustement for cells cultivated at low pH with an important shift from mixed acid fermentation to butanediolic fermentation. Finally, we demonstrate the importance of exofacials thiols groups in the reductive abilities of B. cereus. All these conclusions will help to better understand the response of B. cereus exposed to acid stress and Eh

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
As plantas não possuem mecanismos de defesa específicos para combater a diversidade de estresses abióticos e poluentes do ambiente, e sua sobrevivência depende da flexibilidade e adaptação dos seus próprios mecanismos de defesa naturais. Além disso, a manutenção da homeostase celular depende de vários mecanismos interligados e complexos, enquanto o sistema de defesa celular não segue um padrão específico de ação e pode ainda variar devido a vários fatores tais como a espécie do vegetal, o tempo de exposição ao estresse, o estágio de desenvolvimento da planta e também nos diferentes órgãos e tecidos analisados. Com base nessas considerações, esta dissertação teve como objetivo destacar e investigar o papel do Enxofre (S) e do Selênio (Se) contra diferentes estresses nas plantas, através das respostas enzimáticas, não enzimáticas e também outros mecanismos de defesa relacionados. No primeiro capítulo, o autor caracteriza os mecanismos bioquímicos gerais da defesa celular antioxidante, especificamente a formação das espécies reativas de oxigênio (EROs) e suas singularidades químicas e o estresse oxidativo induzido, o sistema de defesa antioxidante enzimático, especificamente as enzimas Superóxido Dismutase (SOD) e a Catalase (CAT), os mecanismos não-enzimáticas contra o estresse, incluindo o ciclo Aascorbato-Glutationa, a GSH (glutationa reduzida), as fitoquelatinas e também a formação de prolina. O estado nutricional da planta durante o estresse é crucial a fim de manter uma resposta de defesa adequada. Em vista disso, o capítulo dois apresenta uma revisão sobre a participação de Enxofre (S) na defesa contra o estresse. Este nutriente tem um papel importante em processos fundamentais, tais como o transporte de elétrons, estrutura, regulação, produção de oxigênio fotossintético, resistência a estresses abióticos e bióticos e no metabolismo secundário. Além disso, alguns elementos químicos são considerados benéficos para as plantas, no qual o Selênio (Se) é o mais relevante. No capítulo três, o autor descreve o papel do Se na amenização do estresse induzido pela contaminação por metais pesados, suas poderosas características antioxidantes, a melhoria da atividade de enzimas antioxidantes e também dos mecanismos globais de defesa. O capítulo quatro consiste em um projeto científico conduzido pelo autor. O objetivo deste estudo foi investigar se o Selênio, sob a forma de selenito (Na2SeO3), é capaz de evitar a absorção, translocação e concentração de cádmio (CdCl2), em diferentes tecidos no tomate, indicando os possíveis mecanismos para amenizar o estresse, bem como também analisar o estado geral dos frutos através das análises nutricionais, peso seco, pigmentos e concentração de Prolina livre. Os resultados demonstram que efeito atenuante do Se em tomateiro submetido ao Cd poderia estar relacionado com a restrição da absorção e translocação de Cd2+, aumentando a concentração de micronutrientes nos frutos e, finalmente, aumentando a concentração de prolina livre nos frutos.
Plants do not have specific defense mechanisms to counteract the diverse range of abiotic stresses and pollutants into the environment, and its survival depends on the flexibility and adaptability of its own natural defense mechanisms. Furthermore, the maintenance of cellular homeostasis depends on several interlinked and complex mechanisms, while the cellular defense system does not follow a specific pattern of action and may differ due to various factors such as plant species, exposure time to the stress, plant developmental stage, different organs and tissues analyzed. In the light of these considerations, this dissertation aimed to highlight and investigate the role of Sulfur and Selenium against different plant stresses, through the enzymatic and non-enzymatic plant responses and other related defense mechanisms. In the first chapter the author characterize the general biochemical mechanisms of the antioxidant cell defense, specifically the reactive oxygen species (EROs) formation and its chemical singularities and the induced oxidative stress, the enzymatic antioxidant defense system, specifically the superoxide dismutase (SOD) and Catalase (CAT) enzymes, the non-enzymatic mechanisms against the stress, including the Ascorbate-Glutathione cycle, the GSH (reduced glutathione), the phytochelatins and also proline formation. The plant nutritional status during the stress is crucial in order to maintain a proper defense response. In view of this, the chapter two is a published review about the participation of Sulfur (S) on the stress defense. This nutrient has a role in fundamental processes such as electron transport, structure, regulation and it is also associated with photosynthetic oxygen production, abiotic and biotic stress resistance and secondary metabolism. Moreover, few chemical elements are considered benefic to plants, while Selenium (Se) is the most relevant. In the chapter three the author describes the role of Se to detoxify the stress induced by heavy metal contamination, its powerful antioxidant characteristics and the improvement of the antioxidant enzymes activity and overall defense mechanisms. The chapter four consists of a scientific project conducted by the author. The aim of this study was to investigate whether Selenium, under the form of selenite (Na2SeO3), may avoid the uptake, translocation and concentration of Cadmium (CdCl2), in different tomato tissues, indicating possible mechanisms to counteract the stress, as well as to analyze the fruits overall status through the nutritional analyses, dry weight, pigments and proline concentration. The results demonstrate that alleviating effect of Se in tomato under Cd contamination could be related to restriction of Cd2+ uptake and translocation, enhancing micronutrient concentration in fruits and, finally, enhancing fruit proline concentration.
CAPES: 445978/2014-7

De par leur importante diversité phénotypique (10000 espèces), les oiseaux ont colonisé la plupart des niches écologiques, aussi " extrêmes " soient-elles. Les zones polaires (Arctique et Antarctiques) et le climat extrêmement froid qui les aractérise, suscitent l'intérêt de nombreuses études. Ce travail de thèse avait pour but d'explorer les différents mécanismes intervenant dans la mise en place de la thermorégulation chez l'oiseau. Nous nous sommes principalement intéressés, par une approche intégrative, de l'animal entier (méthodes de calorimétrie indirecte) à l'expression génique (techniques de RT-PCR), à caractériser les modifications métaboliques et l'implication d'une protéine découplante (avUCP) dans les mécanismes de thermorégulation, et principalement la thermogenèse sans frisson (NST) en réponse à une exposition chronique au froid.Au cours de deux études menées chez le caneton de Barbarie, nous avons démontré l'aspect " adaptatif " de la NST ainsi que l'implication potentielle de l'UCP aviaire dans ce mécanisme en faisant varier tout d'abord la température d'acclimatation puis la durée d'exposition pour caractériser la mise en place de la NST au cours de la croissance. Lors d'une troisième étude, nous nous sommes intéressés à une étape clé de la vie des manchots royaux (passage en mer) caractérisée par un stress thermique important et une activité physique accrue dus aux longs séjours en eau froide. Ce contexte environnemental et physiologique entraine nécessairement des adaptations métaboliques, comme la mise en place d'un métabolisme lipidique efficace soutenant ainsi les dépenses énergétiques accrues lors des voyages en mer.

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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
O crescimento populacional mundial tem contribuído para uma maior demanda de arroz, enquanto que alterações ambientais, causadas pelo homem, contribuem com o aumento da frequência de precipitações. Estas condições formam um ambiente de hipoxia, e restringem a produção do arroz. Frente a isso as plantas respondem com adaptações morfológicas e alterações em nível molecular. Portanto, este trabalho teve como objetivo avaliar os efeitos morfológicos e anatômicos em cultivares de arroz Oryza sativa L. submetidas a hipoxia e verificar o perfil de expressão dos genes de regulação complexa e simples de fatores de transcrição WRKY envolvidos na resposta ao estresse por hipoxia. Os resultados obtidos demonstraram que ocorre alterações morfológicas e anatômicas nas cultivares de arroz irrigado quando submetidas ao estresse por hipoxia, principalmente no sistema radicular. Ainda, o aerênquima é mais desenvolvido nas cultivares Epagri 108 e Nipponbare quando submetidas ao estresse por hipoxia. No estudo de expressão gênica através da técnica de qRT-PCR, foi possível observar que os genes WRKY responderam ao estresse por hipoxia, mas não foi possível, para este estresse, verificar uma diferença entre a resposta do perfil de expressão dos genes de regulação simples e complexa em plântulas de arroz sob estresse por hipoxia.
The growth of the world’s population has contributed for a greater demand of rice while environmental alterations caused by men contribute to an increase of rainfall. This conditions create a hypoxia environment and restrict the production of rice. Under these conditions, plants with morphological adaptations and alterations in molecular level. Thus, this work had as its objective to evaluate the morphological and anatomical effects in rice cultivars Oryza sativa L. submitted to hypoxia and to verify the expression profile of genes of complex and simple regulation of WRKY transcription factors involved in the response of stress by hypoxia. The results obtained demonstrated that morphological and anatomical alterations occur in cultivars of irrigated rice when submitted to stress by hypoxia, manly in their root system. Furthermore, the aerenchyma is more developed in the cultivars Epagri 108 and Nipponbare when submitted to stress by hypoxia. In the study of genic expression through the qRT-PCR technique, it was possible to observe that the WRKY genes responded to stress by hypoxia but it not possible, for this stress, to verify a difference between the response of the expression profile of genes of simple and complex regulation in seedlings of rice under stress by hypoxia.

Exercise training is known to increase endothelial function and provoke arterial remodelling both locally and systemically. This thesis was designed to further examine these relationships by investigating the acute response to different exercise intensities, with and without shear rate modification. Shear rate modification was also used to examine the impact of systemic exercise training on brachial haemodynamics. Finally, the effect of inactivity on vascular function and arterial remodelling were studied using novel models of inactivity. The aim of Study 1 was to examine the effect of shear stress on upper limb brachial artery dilation during acute cycle exercise of different intensities. The impact of three randomised bouts of 30 mins leg cycling (50, 70 and 85% HRmax) on brachial artery blood flow, shear rate (SR) and brachial diameter, was measured bilaterally and simultaneously. SR was further manipulated in one arm via forearm heating (40±1°C) in a water bath (+0C) throughout the exercise bouts. Exercise induced stepwise increases in SR in the unheated arm (~0C) (P<0.05). In the +o( arm, SR was significantly greater than in the ~o( limb. Brachial artery diameter increased post- exercise in ~o( by 3% (50%HRmax; P>0.05 vs. baseline), 7% (70%HRmax; P<0.05) and 9% (85%HRmax; P<0.05). In the+°C arm, post-exercise brachial diameter increased at all exercise intensities (P<0.05) and was significantly greater (P<0.05) than in the ~°C limb at 50% (12%), 70%HRmax (14%) and 85%HRmax (15%). In conclusion, increases in shear rate during incremental lower limb exercise are associated with increases in brachial artery diameter. This response is exaggerated with larger SR induced by localised heating, indicating that leg exercise has systemic effects on arterial diameter and that SR is an important stimulus to vasodilation during exercise in humans. The second study examined brachial artery flow mediated dilation (FMD) (using high resolution echo-Doppler) pre, and post (0, 1, 2, 24hr) 3 bouts of acute 30 min exercise at different (50, 70 and 85% HRmaxl intensities. Shear rate area-under-the- curve (from cuff deflation to peak dilatation; SRAUcl was calculated as the eliciting stimulus for FMD. Both baseline diameter and SRAUC were elevated by exercise. With covariate-control of these variables, the change in brachial artery FMD was negligible after exercise (~5 minutes post exercise) at 50% HRmax (6.3±2.6 vs. 5.9±2.5%; 95%(1 for difference: -0.59 to 1.34%) whilst a larger changes in FMD were noted after the exercise bouts at 70% (6.1±1.8 vs. 4.7±1.9%; 95%(1 for difference: 0.08 to 2.58%) and at 85% HRmax (6.6±1.6 vs. 3.6±2.2%; 95%(1: 0.41 to 5.42%). A further 2-way ANOVA revealed there were no changes in FMD at any other time- point post exercise (1, 2, 24hrs) and FMD normalised by Ihr post. These data indicate, for the first time, a 'dose-response' relationship between exercise intensity and the reduction in FMD, even when exercise-mediated changes in shear and baseline diameter are accounted for. The purpose of Study 3 was to examine the contribution of shear stress to changes in vascular function in the non-exercising upper limbs in response to lower limb (systemic) cycling exercise training. Subjects participated in an 8-week cycle training study undertaken at 80% HRmax, with unilateral cuff inflation around the forearm during each exercise bout. FMD, partly NO-mediated endothelial function (i.e. ischaemic handgrip exercise (iEX)), and endothelium-independent dilation to a NO donor (i.e. glyceryl trinitrate (GTN)) were measured at 2, 4 and 8 weeks. Cycle training increased FMD in the non-cuffed limb at week 2 after which, responses returned towards baseline levels (5.8±4.1, 8.6±3.8, 7.4±3.5, 6.0±2.3 at 0, 2, 4 and 8 weeks, respectively; ANOVA: P=0.04). No changes in FMD were observed in the cuffed arm. In addition, no changes were evident in response to iEX or GTN in either the cuffed or non-cuffed arms (P>O.05) across the 8 week intervention period. These data suggest that lower limb cycle training induces a transient increase in upper limb vascular function in healthy young humans which is, at least partly, mediated via shear stress. Exercise training is associated with rapid changes in endothelial function, which occur within days of starting training. Whilst long-term physical inactivity has a strong effect on vascular structure, little is known about the immediate impact of inactivity on vascular function. Therefore, Study 4 measured changes in vascular function before, during (day 4) and after 8 days of unilateral forearm inactivity induced by wearing a sling on the non-dominant arm. Maximal handgrip strength of the inactive forearm decreased after 8 days, confirming physical deconditioning. There were no significant changes in brachial artery baseline diameter, FMD, iEX or GTN across the 8 days in either arm (P>0.05). A significant decrease in peak blood flow was found in the intervention arm (2-way interaction: P=0.03) that is suggestive of remodelling of forearm resistance vessels. However, measures of (largely and partly) NO-mediated endothelial conduit artery function were not altered across an 8 day period of inactivity. Whilst increases in mean arterial shear stress are known to induce improvements in arterial function and remodelling in humans, animal data have demonstrated that retrograde shear is associated with pro-atherogenic effects. However, relatively little is known regarding the effect of retrograde shear rate on vascular function in humans in vivo. In order to provoke retrograde shear, subjects wore a compression sleeve on one forearm for 8 clays. Measurements were taken before and during acute (lhr) exposure to a compression sleeve on baseline day O. Measurements were taken after 4 and 8 days exposure to the compression sleeve. There were no significant changes in mean or antegrade shear rate during exposure to the compression sleeve. However, the compression sleeve resulted in an immediate increase in retrograde shear rate in 6 subjects (PO.05, control-group)i.e. subjects in whom the compression sleeve did not increase retrograde shear were the control group. The intervention group demonstrated a significant decrease in FMD after 1 h compression sleeve (PO.05). After 8-days using the compression sleeve, no significant changes in FMD, iEX, or GTN-response in the intervention and control group (all P>O.05) were observed. In conclusion, short-term increases in retrograde shear rate decrease FMD, but not chronically. Data in this thesis provide evidence for the role of blood flow and shear stress, as a result of exercise and inactivity, and its immediate effects upon the vasculature.

Multi environment trials conducted over mapping population are often used to test genotypes in a set of environments that represent the target environmental range. The first part of this work is the evaluation of the ‘Nure’ x ‘Tremois’ double-­‐haploid mapping population, together with an association panel comprising 185 barley varieties representative of the barley germplasm cultivated in the Mediterranean basin. Plant material was tested across eighteen site by year field trials combination, in six countries across the Mediterranean basin. Trials were growth at sites contrasting for natural rainfall (high vs low on the base of past meteorological data) or at the same site with one being rainfed and the other with supplementary irrigation. Trials conducted for two years in each one of the sites and this allowed tocollect a huge data series comprising agronomical traits defining grain yield and yield components, phenological and environmental data, subsequently used to identify genomic regions involved in barley adaptation. The 118 doubled haploid lines of the mapping population were genotyped with Diversity Array Technology® (DaRT) marker assay and subsequently a total of 15 CAPS and SSCP marker for candidate genes involved in phenology regulation and abiotic stress response were added to the linkage map based on DaRT markers. Data collected were firstly used to perform QTLs analysis with composite interval mapping for any environment/ trait combination, results showed eight QTLs for grain yield, days to heading and grain yield components. . The two mostly frequents QTLs for grain yield and days to heading were located on barley chromosome 1H (3 trials), 2H (8 trials) and 5H (5 trials) overlapping respectively HvFT3 gene, the earliness per se locus (eam6/Eps-­‐2) and the vernalization gene Vrn_H1. A further QTL multi-­‐environment analysis was performed and revealed that across the 18 field trials QTL for eam6/Eps-­‐2 (2H) and Vrn-­‐H1 (5H) were commons for days to heading and grain yield. We use all the environmental information collected to check QTLs sensitivities to co-­‐environmental co-­‐variables. Most of significant associations collected were related to temperature and temperature-­‐based variables troughtout the growing cycle. Eam6/Eps-­‐2 showed non-­‐crossover QTL.E interaction, while for Vrn-­‐H1 crossover interactions were revealed. The 185 barley accession were genotyped with 1536 SNPs and data collected for this population for cold resistance in two field trials in Spain an Italy, the first trial was characterized by an exceptional winter, while the second was previously know has frost-­‐prone environment. Results from genome wide association analysis showed 13 positive associations with specific genomic regions. Interestingly several of these QTL were coincident with the position of previously mapped loci for cold tolerance, on chromosomes 2HL, 4HL and 5HL.
Els assajos en localitats múltiplas de poblacions de mapeo s'utilitzen freqüentment per a testar genotips en un conjunt d'ambients representatius de la condicions climàtiques on es volen introduir aquests genotips. La primera part d'això treball ha estat l'avaluació de la població de mapeo ‘Nure x Tremois’ constituïda de 118 de doble haploides d'ordi, juntament amb panell d'associació que comprèn 185 varietats d'ordi representatives del germoplasma conreat en la conca Mediterrània. El material vegetal ha estat assajat en una combinació de divuit camps per any desllorigats en sis països de la conca mediterrània. Els assajos s'han portat a terme en camps amb diferent disponibilitat d'aigua, classificats sobre la base de les dades relatives a les freqüència i quantitat de les precipitacions o en el mateix lloc amb un camp en secà i altre regat. Els assajos es van portar a terme per dos anys en cada localitat i això va permetre la recollida d'un gran volum de dades que comprenen caràcters agronómicos relacionats amb rendiment i components del rendiment, dades fenológicos i ambientals. Aquestes dades es van utilitzar després per a la identificació de regions genomicas involucrades en l'adaptació de l'ordi a l'ambient. Els 118 dobles haploides de la població ‘Nure x Tremois’ es genotiparon amb marcadors DaRT (Diversity Array Technology), després un set de 15 marcadors CAPS I SCCP per a gens candidats involucrats en la regulació de les fases fenológicas van ser afegits al mapa de lligament construït amb els marcadors DaRT. Les dades van ser utilitzats per a fer una anàlisi de QTL amb procediment ‘Composite Interval Mapping’ para cada combinació ambienti/ caràcter. Es van trobar diversos QTLs per rendiment i data d'espigolat i components del rendiment. Els QTL mes freqüents trobats per rendiment i data de floració i components del rendiment estan localitzats en els cromosomes 1H (3 camps), 2H (8 camps) i 5H (5 camps) coincidents respectivament amb HvFT3 locus, eam6/Eps-­‐2 (earliness per se) locus i amb el locus de vernalización Vrn-­‐H1. Una ulterior anàlisi de QTL feta amb el mètode “Multi Environment Trial” ha revelat que els QTL localitzats en el locus eam6/Eps-­‐2 (cromosoma 2H) i Vrn-­‐H1 (cromosoma 5H) són comunes per rendiment i data de floració en els 18 camps d'assaig. Per això utilitzem tots el dades ambientals col·leccionades durant tot el cicle del cultiu per a investigar la sensibilitat de dites QTL a les co-­‐variables ambientals. La majoria de les associacions oposades estan relacionades amb temperatures i variables relacionades amb aquestes. Eam6/Eps-­‐2 mostra una interacció de tipus quantitatiu amb aquestes variables mentre Vrn-­‐H1 mostra una interacció de tipus qualitatiu amb aquestes variables. Les 185 varietats assajades van ser genotipadas amb 185 SNPs i fenotipadas per resistència a fred en dos assajos uneixo a Espanya i altre a Itàlia. El primer assaig va ser caracteritzat per un hivern excepcionalment fred, mentre el d'Itàlia ha estat utilitzat en passat per testar resistència a fred a causa de els hiverns rígids que solen registrar-­‐se en aquesta localitat. Les dades van ser utilitzats per a portar a terme la analisis GWAS “Genome Wide Association Analysis” . Els resultats van permetre identificar 13 regions genomicas involucrades en la resistència a frio. Entre elles tres regions coincideixen amb loci ja mapeados i coneguts per ser involucrats en la resposta a frio en los cromosomes 2HL, 4HL i 5HL.
Los ensayos en localidades múltiplas de poblaciones de mapeo se utilizan frecuentemente para testar genotipos en un conjunto de ambientes representativos de la condiciones climáticas donde se quieren introducir dichos genotipos. La primera parte de esto trabajo ha sido la evaluación de la población de mapeo ‘Nure x Tremois’ constituida de 118 de doble haploides de cebada, junto con panel de asociación que comprende 185 variedades de cebada representativas del germoplasma cultivado en la cuenca Mediterránea. El material vegetal ha sido ensayado en una combinación de dieciocho campos por año dislocados en seis países de la cuenca mediterránea. Los ensayos se han llevado a cabo en campos con diferente disponibilidad de agua, clasificados en base a los datos relativos a las frecuencia y cantidad de las precipitaciones o en el mismo sitio con un campo en secano y otro regado. Los ensayos se llevaron a cabo por dos años en cada localidad y esto permitió la recogida de un gran volumen de datos que comprenden caracteres agronómicos relacionados con rendimiento y componentes del rendimiento, datos fenológicos y ambientales. Dichos datos se utilizaron después para la identificación de regiones genomicas involucradas en la adaptación de la cebada al ambiente. Los 118 dobles haploides de la población ‘Nure x Tremois’ se genotiparon con marcadores DaRT (Diversity Array Technology), después un set de 15 marcadores CAPS Y SCCP para genes candidatos involucrados en la regulación de las fases fenológicas fueron añadidos al mapa de ligamento construido con los marcadores DaRT. Los datos fueron utilizados para hacer una análisis de QTL con procedimiento ‘Composite Interval Mapping’ para cada combinación ambiente/ carácter. Se encontraron varios QTLs por rendimiento y fecha de espigado y componentes del rendimiento. Los QTL mas frecuentes encontrados por rendimiento y fecha de floración y componentes del rendimiento están localizados en los cromosomas 1H (3 campos), 2H (8 campos) y 5H(5 campos) coincidentes respectivamente con HvFT3 locus, eam6/Eps-­‐2 (earliness per se) locus y con el locus de vernalización Vrn-­‐H1. Una ulterior análisis de QTL hecha con el método “Multi Environment Trial” ha revelado que los QTL localizados en el locus eam6/Eps-­‐2 (cromosoma 2H) y Vrn-­‐H1 (cromosoma 5H) son comunes por rendimiento y fecha de floración en los 18 campos de ensayo. Por esto utilizamos todos lo datos ambientales coleccionadas durante todo el ciclo del cultivo para investigar la sensibilidad de dichos QTL a las co-­‐variables ambientales. La mayoría de las asociaciones encontradas están relacionadas con temperaturas y variables relacionadas con estas. Eam6/Eps-­‐2 muestra una interacción de tipo cuantitativo con dichas variables mientras Vrn-­‐H1 muestra una interacción de tipo cualitativo con dichas variables. Las 185 variedades ensayadas fueron genotipadas con 185 SNPs y fenotipadas por resistencia a frío en dos ensayos uno en España y otro en Italia. El primer ensayo fue caracterizado por un invierno excepcionalmente frío, mientras el de Italia ha sido utilizado en pasado por testar resistencia a frío debido a los inviernos rígidos que suelen registrarse en dicha localidad. Los datos fueron utilizados para llevar a cabo la analisis GWAS “Genome Wide Association Analysis”. Los resultados permitieron identificar 13 regiones genomicas involucradas en la resistencia a frio. Entre ellas tres regiones coinciden con loci ya mapeados y conocidos por ser involucrados en la respuesta a frio en los cromosomas 2HL, 4HL y 5HL.

L’objectif est d'établir des repères qui pourraient permettre une meilleure prédiction quant aux facultés de maîtrise et de décision des joueurs de basket-ball en situation stressante. Problématique: le basketteur de haut niveau présente-t-il des caractéristiques psychologiques lui permettant de faire face a la situation de stress a laquelle il est confronte? Est-il possible de déterminer un profit de basketteur capable de faire face efficacement dans ces conditions? Hypothèse: l'évaluation psychologique du basketteur permet d'établir une relation entre sa performance, et la détection d'une dominante, ou cognitive, ou affectivo-émotionnelle, ou sociale, ou d'une combinaison des trois à partir de ce constat, on peut en déduire des applications dans le domaine de la détection, de l'accompagnement et du soutien à l'entrainement et a la compétition. Une étude différentielle portant sur 140 basketteurs (dont 44 relèvent du haut niveau) et 370 sujets de référence est conduite avec pour objectif la recherche de caractéristiques propres aux basketteurs, et particulièrement de celles qui caractérisent le haut niveau. L'étude ayant un aspect multidimensionnel utilise de nombreux instruments psychologiques essentiellement destines à des sujets "dit normaux". La démarche en entonnoir commence par une comparaison des basketteurs à des populations dites normales pour se terminer par une comparaison à la performance propre des basketteurs eux-mêmes. La seconde partie plus clinique aborde des suivis longitudinaux possibles. Les résultats pourraient, contrairement a certaines idées reçues, qualifiant les joueurs de basket ball "comme ayant des tendances marquées a la socialisation", signifier qu'ils manifestent plutôt des défenses par rapport à leur environnement". Certains résultats indiquent que les meilleurs investiraient moins d'énergie dans les moyens de défenses que les autres joueurs
The subject is to establish indicators which could allow a better prediction of self control and decisive abilities of basket ball players in situation of stress or strain. Problematic : does the top ranking basket ball player present the psychological features to cope a situation of stress. Is it possible to establish a basket ball player profile able to cope under pressure. Hypothesis : the psychological evaluation of basket ball player establishes a relationship between his performance and the detection of a dominant characteristic, either cognitive, emotional or social, finally both of them. From this assessment we can deduct applications in the field of detection, supersion and support in training and competitive situations. A differential study in which 140 basket ball players among them 44 are top ranking and 370 reference subjects is led for a research of particular basket ball players features and in particular for top rankers. This study with a multidimensional aspect uses many psychological instruments essentially meant for "normal" subjects. With the help of a filtering method, it starts with a comparison between basket ball players and normal people and ends with a comparison with the performance of these basket ball players themselves. The second part is more clinic and is built on a steady work repated during several years. The results could unlike generally accepted ideas qualify the basket ball players to have "marked tendencies for socialization" rather to be "tinged with defence connected with their environment". Some of those results might show that the best players would invest less energy in defence than than the others

La betaine est un osmoprotecteur universel et permet a toutes les cellules vivantes capables de la synthetiser ou de l'accumuler de mieux resister a la perte d'eau. L'etude de l'adaptation au stress hyperosmotique chez lactococcus lactis vise la comprehension et le controle de la survie aux stress osmotique chez les bacteries, notamment dans les alimentsau et niveau de leur usage industriel. Les fonctions essentielles dans la reponse au stress osmotique ont ete recherchees par mutagenese insertionnelle. Chez notre souche modele, la capacite a transporter la betaine est indispensable a la croissance en presence de nacl. L. Lactis possede un systeme de transport de la betaine original, appele busa : il est constitue de deux proteines, dont l'une, bi-fonctionnelle, resulte de la fusion du canal transmembranaire et du domaine de liaison du substrat. Busa est un osmosenseur, active par l'augmentation de l'osmolarite. La transcription de l'operon busa est tres fortement stimulee par un choc hyperosmotique. L'activation de busa depend de la composition en lipides membranaires, modifiee a forte osmolarite. L'etude de la diversite de la reponse au stress osmotique de l'espece l. Lactis montre que la capacite a se developper en presence de nacl est liee a la presence et a l'expression de busa chez les souches testees. Les souches osmosensibles presentent differents degres de perte de fonction, des pseudogenes a l'absence d'operon. Chez un autre mutant osmosensible, nous avons identifie un gene de fonction inconnue, dont l'interruption compromet la croissance a forte osmolarite en absence de betaine. Ce phenotype s'accompagne d'une croissance en biofilm osmodependante et d'une forte adhesion a certains materiaux abiotiques (acier, polystyrene). La complementation fonctionnelle du mutant avec une copie sauvage du gene touche restaure la croissance a forte osmolarite, mais n'a pas d'effet sur la croissance en biofilm.

The food-borne pathogen Listeria monocytogenes is more salt tolerant in the complex medium brain heart infusion (BHI, 2.0M NaCI upper limit for growth) than in a chemically-defined medium (DM, 1.0M NaCI upper limit for growth). The components in BHI responsible for the characteristic salt tolerance of L. monocytogenes are peptone and glycine betaine. At high osmolarity, the growth stimulation by peptone was higher than expected from nutritional supplementation, indicating that an osmoprotective mechanism was also at play. Peptone provided a higher level of osmotic protection than the compatible solute glycine betaine which was a moderate osmoprotectant. Our growth data demonstrated that of the free amino acids and peptides contained in peptone it is the peptides which are the osmoprotectants for L monocytogenes. Furthermore, specific peptides, such as PGG (prolyl-glycyl- glycine) and PHP (prolyl-hydroxyproline), behaved in growth experiments as the compatible solute glycine betaine, i.e. stimulation of growth at high osmolarity and no effect at low osmolarity. Our analysis of the changes in the intracellular pools of amino acids, under conditions of sosmotic stress, when peptone or specific peptide are supplied to the growth medium, has shown the following features in the mechanism of adaptation of L. monocytogenes to osmotic stress: i) Peptides are taken up, by at least two specific transport systems. ii) Subsequently, peptides are hydrolysed intracellularly by peptidases. iii) As a consequence of ii), a significant increase in the pool of free amino acids occurs. Osmoadaptation in L. monocytogenes iv) We have also demonstrated that depending on the nature of the constituent amino acids, some peptides are not fully hydrolysed which leads to the accumulation of an intracellular peptide pool in L. monocytogenes. v) Proline, glycine and hydroxyproline are the amino acids preferentially accumulated as free amino acids or as part of peptides. vi) The intracellular accumulation of free amino acids and peptides is positively correlated to an increase in the external osmolarity and has an important role in the osmoadaptation of L. monocytogenes.

The experiments described in this thesis sought to test two putative functions of the amygdala. The first set of experiments was aimed at asking whether small and large amygdala lesions are capable of blocking responses to acute unconditioned stress. The second set of experiments sought to determine what role the amygdala may play in adapting to stress. The bulk of previous literature on the amygdala show its role in gaining emotional responses to situations. A role in adaptation to stress would require the amygdala to be able to drive less and less response to a repeated stimulus over time. In order to model stress in the laboratory, restraint stress of Lister Hooded rats was employed in these studies. Stress was measured experimentally by a variety of measures. Plasma levels of the stress hormone corticosterone was measured by radio-immuno-assay. Expression of c-fos mRNA measured by in situ hybridisation was used as a non-specific marker of neuronal activation in the brain. Expression of corticotropin releasing hormone (CRH) and arginine vasopressin (AVP), peptides critical in controlling corticosterone secretion and known to be modulated by stress, were measured in the paraventricular hypothalamic nucleus (PVN) also by in situ hybridisation. Telemetry was used to measure heart rate an indicator of the autonomic response to stress. Two types of lesion were studied, neurotoxic lesions of the central nucleus of the amygdala (CeA), and neurotoxic lesions of the entire amygdaloid complex including the central nucleus, lateral, basolateral, basomedial, medial and cortical nuclei (AMY). In all experiments, lesioned animals were compared with sham operated animals. Lesions were assessed as to their affect on acute stress, and also on adaptation to repeated stress.

Thesis (Ph.D.)--Boston University PLEASE 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.
Bacteria exhibit highly adaptive behaviors in the face of stress, which poses significant challenges for the eradication of infectious disease as well as for the success of biotechnology efforts to harness microbes as production chassis. Systems biology, which studies interactions between the components of a biological system, presents a framework for using computational strategies to further understand the complexity of bacterial physiology. In this work we use systems biology to elucidate the comprising mechanisms of two facets of bacterial stress adaptation. In the first part of this work, we develop a method to facilitate the characterization of small non-coding RNAs, which are involved in mediating adaptive physiological responses to changing environmental conditions. We implement a network biology approach based on expression profiling to predict the functional and regulatory interactions for small RNAs in Escherichia coli. We experimentally validate functional predictions for three small RNAs in our inferred network and demonstrate that a specific small RNA interacts with a transcription factor in a mutually inhibitory relationship, demonstrating a new cellular regulatory motif in bacteria. In the second part of this work, we investigate the role of phages, viruses which infect bacteria, in the adaptation of the microbiome to stressful environments. Disruption of intestinal homeostasis has been studied at the level of microbial composition; however, investigation of the gut ecosystem has evinced a myriad of resident phages, and it remains unclear how perturbation of the gut environment affects these viral symbionts. Our analysis demonstrates that antibiotic treatment, a prevalent stress for commensal microbes, enriches the phage metagenome for stress-specific and niche-specific functions. We also show that antibiotic treatment expands the interactions between phage and bacterial species, leading to a more highly connected phage-bacterial network for gene exchange. Our work indicates that the adaptive capacity of the phageome may represent a community-based mechanism for protecting the gut microfiora and preserving its functional robustness during antibiotic stress. Systems biology approaches toward understanding bacterial behavior within an environmental and evolutionary context may improve our relationships with microbes, which will be critical in an era where the potential of these organisms remains both promising and incipient.

Afin de repeupler la mer Caspienne, la propagation artificielle de l’esturgeon Acipenser persicus est maintenant une pratique courante avec rejets annuels de juvéniles directement en mer. Cependant, une forte mortalité est régulièrement observée suite à la libération directe en mer de juvéniles pesant 2-3 g. L'objectif a donc été d'analyser les capacités d’acclimatation de juvéniles de l’eau douce à l’eau saumâtre et d'identifier un moyen possible d’améliorer les taux de survie d’esturgeons de moins de 3 g.Dans une première partie, l'effet de transferts abruptes ou progressifs sur 5 jours de l'eau douce (ED) à une salinité de 11‰ (salinité de la mer Caspienne, CSW) a été étudié chez des juvéniles de 1 à 2 g, 2 à 3 g et de 3 à 5 g. Ont été mesurés les taux de mortalité, l'osmolalité plasmatique, l’expression et la localisation (branchies, reins, valvule spiralée, caecum pylorique) des principales protéines de transport : la Na+, K+-ATPase (NKA), la H+-ATPase vacuolaire (VHA), le Na+, K+, 2Cl- (NKCC) et la ‘Cystic Fibrosis Transmembrane conductance Regulator’ (CFTR). Une étude des changements d'expression génique et protéique de la NKA au niveau des branchies a également été effectuée. Enfin, une étude ultrastructurale (TEM et SEM) des cellules à chlorure branchiales a été effectuée.Dans une deuxième partie, un traitement hormonal avec le cortisol a été effectué afin d’améliorer la capacité d'acclimatation. Des juvéniles de moins de 2g ont été traités pendant 24h en ED avec des bains de cortisol à 3 concentrations différentes : 3, 5 et 7 mg.l-1. Les poissons ont été ensuite directement transférés de l'eau douce à la CSW et échantillonnés après 1, 4 et 9 jours après transfert en CSW. Les taux de mortalité, l'osmolalité plasmatique, le nombre et l’aire des cellules à chlorure des branchies ont été évalués.Ainsi, les poissons de plus de 3 g sont capables de survivre et s’acclimatent à la CSW. Malgré une augmentation initiale de l'osmolalité plasmatique après transfert de salinité, les juvéniles réduisent ensuite leur osmolalité plasmatique jusqu'à la pression osmotique de la mer Caspienne. Cependant, beaucoup de poissons de moins de 3 g ne peuvent survivre à l’augmentation brutale de salinité et la pression osmotique du sang des poissons survivants reste élevée. L’expression de la NKA et du NKCC, la taille et le nombre des cellules à chlorure des branchies sont également plus élevés. Les juvéniles pesants plus de 2 g augmentent aussi fortement leur activité de NKA branchiale après transfert de salinité. L'étude ultrastucturale a révélé des surfaces apicales similaires pour les cellules à chlorure branchiales des poissons en ED et acclimatés à la CSW. Le cytoplasme de ces cellules dans les poissons pesant plus de 2 g apparait plus dense et gonflé par rapport aux poissons pesant moins de 2 g. Cela pourrait être dû à l'allongement des replis de la membrane basale (réseau tubulo-vésiculaire) et/ou à une densité plus élevée des mitochondries. L’expression branchiale du gène NKA des poissons acclimatés à la CSW est apparue d'abord sur- puis sous-exprimée 4 jours après le transfert de salinité pour atteindre le niveau des poissons en ED. Au niveau intestinal et des reins, aucune différence n'a pu être détectée entre les différents groupes de poids suite au transfert de salinité. Malgré une osmolarité plasmatique réduite, le nombre et la taille des cellules à chlorure des poissons traités avec le cortisol montrent 9 jours après transfert, les mêmes tendances que celles observées pour les poissons non traités.Ainsi, cette étude a révélé que seuls les esturgeons juvéniles de plus de 3 g peuvent être directement rejetés en mer Caspienne. Pour les poissons de 2-3 g, un protocole spécial pendant le transfert de salinité doit être considéré alors que les poissons pesant moins de 2 g ne peuvent tolérer une augmentation de salinité même après un traitement au cortisol
For restocking purposes, artificial propagation of Persian sturgeon (Acipenser persicus) and annual releases into the Caspian Sea are now common practice. However, high mortality is regularly observed following the direct release of 2-3 g juveniles into the Caspian Sea. Therefore, the aim of the study was to analyse the acclamatory capacities of juvenile Persian sturgeons to elevated salinity and to identify a possible way to improve survival rates of juveniles weighting less than 3 grams.In the first part of this study, the effect of abrupt and 5-day gradual salinity transfers from freshwater (FW) to 11‰ Caspian Sea water (CSW) were investigated in juvenile Persian sturgeons with three different weight groups: 1-2 g (1.62 ± 0.27 g), 2-3 g (2.55 ± 0.41 g) and 3-5 g (4.28 ± 0.76 g). Daily mortality rates, plasma osmolality, immunofluorescence localization of the main ion transporter proteins such as Na+, K+-ATPase (NKA), Vacuolar H+-ATPase (VHA), Na+,K+,2Cl–(NKCC) and Cystic Fibrosis Transmembrane conductance Regulator (CFTR) at the gill, kidney, pyloric caecum and intestinal spiral valve levels, ultrastructural studies (TEM and SEM) of the gills for chloride cell changes and changes of branchial NKA gene and protein expression were measured 4 and 10 days after abrupt transfer to CSW and 9 and 15 days after the initial gradual transfer (i.e. 4 and 10 days after reaching CSW), respectively.In the second part of study, hormonal treatment with cortisol was used to enhance the acclimation capability of fish weighing less than 2g. Fish were treated with a cortisol bathing method using three different concentrations; 3, 5 and 7 mg.l-1 for 24 hours in FW. Fish were then directly transferred from FW to CSW (11‰) and sampled after 1, 4 and 9 days post-transfer to CSW. Daily mortality rate, plasma osmolality and branchial chloride cell number and area were evaluated.The obtained results showed that fish weighing more than 3g are able to survive and could successfully acclimate to CSW. Despite initial plasma osmolality increase after salinity transfer, juveniles could reduce their plasma osmolality down to the CSW osmotic pressure after 15 days of acclimation in CSW. However, fish under 3 g could not survive abrupt salinity increase, and blood osmotic pressure of the remaining surviving fish increased and remained elevated during the whole experimental period. At the gill level, higher chloride cell size and number, with also higher NKA and NKCC content were observed allowing juveniles weighing more than 2 g to sharply increase their NKA activity after salinity transfer. The electron microscopic study revealed similar apical surfaces for branchial chloride cells in FW and CSW-acclimated fish. It also indicated that the cytoplasm of these cells in fish weighing more than 2 g were denser and inflated compared to fish weighing less than 2 g. This could be due to the elongation of the basal membrane infoldings (tubulo-vesicular network) and/or a higher density of mitochondria. Because sequences of NKA and NKCC1 genes were not reported for sturgeon fish, two partial sequences of NKA (632 bp) and NKCC1 (538 bp) were obtained from this present study and were registered in Genbank. Branchial NKA gene of CSW-acclimated fish was firstly upregulated and then downregulated to the level for FW fish after 4 days following salinity transfer. At the kidney and intestinal level, no difference could be detected between the different weight groups during salinity transfer. Despite lower plasma osmolality, number and size of the chloride cells in treated fish with cortisol show the same trends as the untreated control fish after 9-days post transfer. Consequently, this study revealed that only Persian sturgeon juveniles weighing more than 3 g can directly be released into the Caspian Sea. Fish weighting 2-3 g need special care during salinity transfer and fish weighing less than 2 g cannot tolerate Caspian Sea salinity even after cortisol treatment

Endochondral bone development depends on the progression of chondrocyte proliferation, hypertrophy and terminal differentiation, which requires precise transcriptional regulation and signaling coordination. Disturbance of this process would disrupt chondrocyte differentiation and lead to chondrodysplasias. In cells, a highly conserved mechanism, ER stress signaling, has been developed to sense the protein load and maintain the cellular homeostasis. In humans, mutations in COL10A1 induce ER stress and result in metaphyseal chondrodysplasia type Schmid (MCDS). Previous analysis of a MCDS mouse model (13deltg mouse) had revealed a novel mechanism of chondrocyte adaptation to ER stress. The hypertrophic chondrocytes survive ER stress by reverting to a pre-hypertrophic like state (Tsang et al., 2007). To dissect the underlying mechanisms that coordinate chondrocyte survival, reverted differentiation and adaptation to ER stress, different chondrocyte populations in the wild type and 13del growth plates were fractionated for global gene expression analyses. The genome-wide expression profiles of proliferating chondrocytes, prehypertrophic chondrocytes, hypertrophic chondrocytes and terminally differentiated chondrocytes in the wild type growth plate provide molecular bases to understand the processes underlying both physiological and pathological bone growth. Systematic analyses of these transcriptomic data revealed the gene expression patterns and correlation in the dynamics of endochondral ossification. Genes associated with sterol metabolism and cholesterol biosynthesis are enriched in the prehypertrophic chondrocytes. Selected genes (Wwp2, Zbtb20, Ppa1 and Ptgis) that may potentially contribute to endochondral ossification were identified differentially expressed in the growth plate. Bioinformatics approaches were applied to predict regulatory networks in chondrocytes at different differentiation stages, implying the essential and dominant roles of Sox9 in coordination of stage specific gene expression. We further confirmed that Sox9 directly regulates the transcription of Cyr61, Lmo4, Ppa1, Ptch1 and Trps1, suggesting that Sox9 integrates different steps of chondrocyte differentiation via regulation of its target genes and partially crosstalk with IHH signaling pathway. The information on gene expression and regulation from physiological growth plate provides important basis to understand the molecular defects of chondrodysplasia. The hypertrophic zone in 13del growth plate was fractionated into upper, middle and lower parts for microarray profiling, corresponding for the onset of ER stress, onset of reverted differentiation and adaptation phase. Comparative transcriptomics of wild type and 13del growth plates revealed genes related to glucose, amino acid and lipid metabolisms are up regulated in response to ER stress. Fgf21 was identified as a novel ER stress inducible factor regulated by ATF4. Removal of Fgf21 results in increasing cell apoptosis in 13del hypertrophic zone without affecting the reverted differentiation process. Up regulation of genes expression related to hypoxic stress (Slc2a1, Hyou1, Stc2 and Galectin3) in 13del hypertrophic chondrocytes suggested that survival and adaptation of chondrocytes to ER stress involve cross-regulation by other stress pathways. Our findings have provided a new insight into the mechanisms that facilitate chondrocyte survival under ER stress in vivo, and propose the integrative effects of hypoxic stress pathway during the stress adaptation process, which broaden the molecular horizons underlying chondrodysplasias caused by protein folding mutations.
published_or_final_version
Biochemistry
Doctoral
Doctor of Philosophy

Two marine algae, Dunaliella parva and Chlorococcum submarinum were selected to study the effect of pH stress on single celled algae. D. parva has been well characterised physiologically, but not with regards to pH stress. C submarinum has not been so extensively studied, but is known to grow over a wide pH range from pH 4.5 to 10.5. It was of prime importance that the algal cells were grown at the desired extreme values of external pH. Problems were encountered at high levels of pH but were overcome by growing the algae in a fermenter set up as a batch culture. This method of growth was used for both algae at extreme values of external pH and it allowed the accurate control of the media pH by the automatic addition of acid or alkali. pH 7.5 cells were grown in normal flask batch culture. The cell number, cell volume, and chlorophyll content of both algae were determined over a wide range of pH values, showing that differences in external pH had significant effects on individual cells. Protein concentrations were measured and were shown to increase in pH 9.0 grown cells. Determination of cell volume, internal pH and membrane potential have been carried out using radiolabelled isotopes for algae grown over a wide pH range. Cell volume was shown to increase at both acid and alkaline pH values. The internal pH of both algae was found to be at a more neutral pH than the external pH. For both D. parva and C submarinum, the membrane potential increased with increasing external pH. Enzyme activities in crude extracts were measured to establish the effects of external pH changes on metabolic pathways. The activity of these enzymes, taken from different organelles in the cell, was used to investigate the uniformity of internal pH.

High soil salinity is a major environmental stress that adversely affects crop production throughout the world. It is now estimated that half of the world’s cropland is affected by salt stress. To cope with various environmental stresses, plants are able to spatially and temporally regulate gene expression through changes in DNA methylation and chromatin conformation, known as epigenetic modifications. Recent studies indicated that epigenetic modifications induced by environmental stress can be inherited over several generations, despite a genomewide epigenetic resetting of epigenetic imprints that takes place during plants reproduction. In this thesis, I evaluated in Arabidopsis thaliana the effect of multigeneration salt stress treatments on the genome-wide dynamics of DNA methylation and tolerance to high salinity. My results show that the immediate progenies of stressed plants displayed better germination and survival rate under high salinity, but contrary to current theories this effect is lost in the following non-stressed generation. Genome-wide DNA methylation analysis revealed that stress induced discrete de novo methylation and demethylation changes on epigenetically labile regions of the plant genome. These acquired tolerance and methylation marks are likely under parent-of-origin control as a result of a robust epigenetic reprogramming that takes place in the male germline. Stress-induced methylation marks identified are associated with transcriptional changes of stress responsive genes and correlated with antisense long-non coding RNA expression. Overall this work establish for the first time a link between differential DNA methylation, gene expression and shortterm adaptation to stress in plants.

Role strain, coping, and adaptational outcomes were examined for a sample of 205 eighth grade adolescents. Differences by gender and family type on amount of role strain, use of coping strategies, and levels of emotional stress and well-being in family and peer roles were identified. Results indicate gender differences in degree of strain experienced in the family role and in use of Social Support and Ventilation as coping strategies. Female adolescents report significantly greater strain than males in family roles. Females, in comparison to males, use Social Support to a significantly greater degree and Ventilation significantly less often as a coping response. Differences by family type were found for the use of Family Support as a coping strategy. Adolescents in single-parent families utilize Family Support as a coping strategy significantly less often than adolescents in two-parent families. Results are discussed and directions for future research are recommended.
Master of Science

Organisms exist in complex and dynamic environments. Facing numerous challenges, microorganisms must continuously monitor environmental changes and adapt to these if they are to survive. For example, the major fungal pathogen of humans, Candida albicans experiences diverse stresses, including temperature fluctuations, oxidative stress and enzymic processes, that cause molecular damage. Post-translational modifications such as phosphorylation play major roles in stress adaptation, for example through activation of MAP kinase pathways and transcription factors such as the heat shock transcription factor, Hsf1. However, other post-translational modifications such as ubiquitination and sumoylation have been relatively understudied. Nevertheless, they are believed to play crucial regulatory roles in many cellular processes including stress adaptation. Therefore, in this study the roles of ubiquitin and SUMO (small ubiquitin-like modifier) have been investigated in C. albicans. Proteomics was used to identify ubiquitination and sumoylation targets, and this was combined with molecular analyses of the UBI4 and SMT3 genes, which encode polyubiquitin and SUMO, respectively. Both ubiquitination and sumoylation were shown to play important roles in morphogenesis, cell division and stress adaptation in C. albicans, including adaptation to heat and oxidative stresses. In addition, the dynamics of heat shock adaptation were examined in C. albicans using a systems biology approach. Hsf1 is known to activate HSP90. In this study, Hsf1 was found to be transiently phosphorylated in response to heat shock, and Hsp90 was found to down-regulate this Hsf1 phosphorylation. This led to the identification of an autoregulatory loop that controls thermal adaptation in C. albicans. A mathematical model of heat shock regulation (constructed in collaboration with Katarzyna Tyc and Edda Klipp) provided novel insights into the regulation of this evolutionarily conserved environmental response and the significance of thermal adaptation during systemic Candida infection.

Small RNA are short, 18-25 nt molecules that regulate gene expression in plants and animals. Two main types, microRNA (miRNA) and short interfering RNA (siRNA) perform this regulation by transcript silencing, translation inhibition, DNA methylation and chromatin remodeling. This thesis is an investigation into small RNA activity in archaeological plant material, specifically barley grain from Qasr Ibrim, a multi-period archaeological site in southern Egypt. It is of particular interest due to its unusual phenotype, suggestive of stunted development that is unexpected in a staple, domesticated cultivar, and the unusual level of DNA and RNA preservation attributable to the extremely arid climate at the site. The research presented here is a comparative analysis of small RNA profiles and epigenetic states of Qasr Ibrim barley and modern, unstressed counterparts. It concludes that differential microRNA and epigenetic profiles are the result of stress response, adaptation, dormancy and / or viral infection unique to the archaeological grain. The primary method of investigation was generation of small RNA sequence data using the Illumina GAIIx platform. This was followed by extensive bioinformatic analysis (RNA diagenesis patterns, miRNA prediction, siRNA target prediction and small genome in silico reconstruction) the results of which were in turn validated experimentally (genomic methylation states, locus-specific methylation analysis and direct miRNA detection). The research represents a twofold contribution to knowledge: first, proof-of-principle that biologically meaningful archaeological RNA can be extracted despite its relative instability to DNA, and second that a unique miRNA profile and epigenetic state is detectable in this particular cultivar of archaeological barley.