Dissertations / Theses on the topic 'Temperature-adaptation'
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Jagdale, Ganpati Baburao. "Adaptation to temperature in entomopathogenic nematodes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq25772.pdf.
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Paget, Caroline Mary. "Environmental systems biology of temperature adaptation in yeast." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/environmental-systems-biology-of-temperature-adaptation-in-yeast(597a675a-aaf1-43bf-bd6c-143aeefc98be).html.
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Temperature is arguably the leading factor that drives adaptation of organisms and ecosystems. Remarkably, many sister species share the same habitat because of their different temporal or micro-spatial thermal adaptation. In this PhD, the underlying molecular mechanisms of the adaptation of closely related species to different temperatures are sought. A thermodynamic analysis was applied to a genome-scale metabolic model of S. cerevisiae at warm and cold temperatures to identify thermo-dependent reactions. Gene Ontology (GO) analysis of predicted cold-dependent reactions found that redox reactions were significantly enriched. A complementary large scale experimental approach was taken by competing 6,000 mutant strains at 16°C to identify genes that were responsible for the fitness at low temperatures. The experiment was carried out in three different nutritional conditions to test the plasticity of temperature dependency. A list of strains whose copy number significantly increased or decreased in all media conditions was constructed and analysed using Gene Ontology. Vitamin biosynthesis, lipid/fatty acid processes and oxido-reduction reactions were all found to be significantly affected by the cold condition. Combining the data from the two studies a list of candidate genes affected by temperature changes were generated. In particular, two genes, GUT2 and ADH3, were identified as potential cold favouring genes and studied in more detailed. Mutants for these two genes were created in a pair of natural sympatric cryotolerant and thermotolerant Saccharomyces yeasts, namely S. kudriavzevii CA111 and S. cerevisiae 96.2, representing an excellent ecological experimental model for differential temperature adaption. My results showed that when compared to the parental strains, both mutants showed lower fitness at cold temperatures as predicted, and in S. kudriavzevii CA111 these mutations significantly improve growth at warm temperatures. Results from all aspects of this work indicate that oxidation reduction reactions are important for cold acclimation. It is known that heat stress causes redox imbalances which are compensated by increasing glycerol production or cytosolic acetaldehyde. Since GUT2 and ADH3 are involved in these processes, mutations in these genes may not be able to compensate for temperature changes. My data also shows that vitamins may also play an important role in cold acclimation which would be an interesting line of investigation for future work. Overall this PhD thesis has incorporated in silico and in vivo work to identify potential processes and genes involved in the temperature adaptation of sister Saccharomyces yeast species. The approach and results provided in this study support the use of a systems biology framework to studying species adaptation to environmental changes, and show that such models can yield testable predictions that may lead to new biological discoveries.
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Hong, Dennis Hwe-Yang. "Temperature adaptation and range expansion of bacteriophage Phi-6 /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2002. http://wwwlib.umi.com/cr/ucsd/fullcit?p3070998.
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Steigenga, Marc Johan. "Adaptation or physiological constraint : temperature-mediated plasticity in reproduction." kostenfrei, 2008. http://opus.ub.uni-bayreuth.de/volltexte/2008/493/.
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Sweeney, Blake Alexander. "Development of a System for Studying Temperature Adaptation of Structural RNAS." Bowling Green State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1321542150.
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Behan, Moira Kathleen. "Homeoviscous adaptation to temperature and pressure. A biophysical and biochemical study." Thesis, University of Liverpool, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279656.
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Butler, Ethan E. "American Maize: Climate Change, Adaptation, and Spatio-Temporal Variation in Temperature Sensitivity." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17463972.
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Agricultural production is vulnerable to climate change. However, this vulnerability can be reduced by adapting food crops to a hotter climate. Many studies have ignored adaptation when quantifying the effect of climate change on crop yield, which has likely overestimated yield losses. Therefore, it is necessary to quantify agriculture's adaptive potential to climate change. Such work is challenging because there are no historical analogues to current or future warming. In place of such a precedent this work explores the varying sensitivity of maize yield to elevated temperatures through a suite of multiple linear regression models. These models use high resolution yield and crop development data available since 1981 in the United States to account for overlooked features of maize physiology and agricultural management. The results of these models substantially alter estimates of how crops will respond to a warming environment.
The studies here illustrate how finer scale details can be incorporated into broader regional models. Temperature sensitivity is found to vary with local climatology indicating that maize cultivars are adapted to their particular environment. Incorporating this historical adaptation into estimates of yield loss substantially reduces the effect of a modest warming. A physiological basis for spatial adaptation is apparent when maize development data are incorporated into the model -- cooler regions accelerate through sensitive development phases faster than hotter areas. The development data also suggest that crop development has been adapted to the seasonal cycle and that a non-trivial portion of the temporal trend in maize yield has resulted from management adjustments. Finally, the importance of spatio-temporal variation in temperature sensitivity is highlighted through case studies of recent years with record-setting yield losses. Spatial and/or temporal variation in temperature sensitivity is necessary to reduce bias in estimates of yield loss in these years.
This work builds from previous conclusions regarding the negative effects of hot temperatures, and suggests that while hotter temperatures will harm maize yields there are steps that farmers might take to manage and reduce these losses. Taken together these results quantify how extant adaptation may help to ameliorate yield losses in a hotter future.Earth and Planetary Sciences
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Gracey, Andrew Y. "Cold-adaptation of carp (Cyprinus carpio L.) : lipid unsaturation and induced desaturase expression." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321117.
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Winnard, Jr Paul. "Cold-Temperature Adaptation of Muscle Creatine Kinase from an Antartic Teleost (Chaenocephalus Aceratus)." Fogler Library, University of Maine, 2001. http://www.library.umaine.edu/theses/pdf/WinnardP2001.pdf.
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Schoenberger, Shirley Ann 1943. "High-temperature adaptation of three Sonoran Desert Bacillus species: Ecological and evolutionary prospects." Thesis, The University of Arizona, 1996. http://hdl.handle.net/10150/278546.
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Growth at high temperature of wild isolates of three species of Bacillus was analyzed to assess potential responses to global warming. Experimental populations were grown at temperatures from 32° to 60° C. The higher temperatures include ones near and above maxima previously reported for laboratory strains. Summer soil temperatures, three centimeters below the ground surface, were recorded at the same site from which the wild isolates came, show that temperatures in the Sonoran Desert often reach 50° to 60° C. The growth data show that the desert isolates of B. subtilis and B. licheniformis have thermal maxima close to those reported by Gordon et al. (1973), while B. megaterium grew well at 2-3°C above the reported maximum. Global Climate Models predict a rise of 1° to 4.5°C over the next 60-100 years. Such a rise could shorten periods of active growth and nutrient cycling by Bacillus decomposers.
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Holden, James Francis. "Ecology, diversity, and temperature-pressure adaptation of the deep-sea hyperthermophilic Archaea Thermococcales /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/11044.
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Boixel, Anne-Lise. "Environmental heterogeneity, a driver of adaptation to temperature in foliar plant pathogen populations?" Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASA010.
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Les facteurs environnementaux, au premier rang desquels la température, ont un impact sur la biologie des micro-organismes foliaires. Ils peuvent aussi modifier significativement leurs dynamiques populationnelles, voire leurs trajectoires évolutives. Classiquement, les modèles épidémiologiques, utilisés pour mieux gérer les maladies des plantes, intègrent l’influence des conditions météorologiques. Ils s’intéressent surtout à des réponses et des effets moyennés, ne tenant compte ni des variations des réponses individuelles, ni de l’hétérogénéité des changements environnementaux aux échelles réellement perçues par les agents pathogènes. Ces deux niveaux de simplification sont acceptables lorsque les états individuels et les variables continues qui leur sont associées, peu diversifiés, sont représentatifs de ceux de l'ensemble de la population. Il en va différemment lorsque les populations présentent des niveaux substantiels de variation individuelle susceptibles d’influencer leur capacité à s’adapter à leur environnement, et, par voie de conséquence, la dynamique des épidémies sous un climat fluctuant ou changeant. Pour mettre en évidence les conséquences de ces hypothèses réductrices, j’ai étudié comment la variation individuelle et l'hétérogénéité environnementale affectent simultanément la fitness, la composition phénotypique et la résilience des populations d'un agent pathogène foliaire (Zymoseptoria tritici) dans des couverts de blé. Trois étapes clés ont structuré l’exploration de ce cas d’étude. Tout d’abord, un protocole in vitro de phénotypage haut débit a été spécifiquement développé, validé et utilisé pour caractériser la diversité des réponses à la température de populations de Z. tritici échantillonnées à des échelles climatiques contrastées (variation spatiale et saisonnière) ainsi que leurs patrons d’adaptation. Les variations environnementales spatio-temporelles rencontrées dans les couverts de blé, considérées comme exerçant des pressions sélectives différentielles sur ces sensibilités thermiques individuelles, ont ensuite été examinées. Enfin, la façon dont la sélection de « thermotypes » (groupes fonctionnels rassemblant des individus présentant une même sensibilité thermique) détermine la dynamique adaptative des populations en réponse à l'hétérogénéité environnementale a été étudiée. Pour cela, des approches expérimentales (in vitro, in planta et in natura) et de modélisation (in silico) ont été couplées. Elles ont notamment porté sur plusieurs générations de populations placées dans des environnements sélectifs de plus en plus complexes. Ces travaux ont montré que le fait de négliger l'amplitude réelle de la variation phénotypique inter-individuelle d'une population microbienne et l'hétérogénéité des pressions de sélection, s’exerçant des échelles phyllo- à mésoclimatiques, conduit à sous-estimer la résilience de cette population, et donc son potentiel adaptatif. Les résultats de cette thèse, à l’interface entre épidémiologie, micrométéorologie et écologie, améliorent notre compréhension d’une part, de l'importance de la variation individuelle dans la dynamique adaptative des populations et, d’autre part, de la manière dont l'hétérogénéité environnementale permet de maintenir des populations globalement très diverses. Elle permet finalement d’expliquer l’existence de patrons d’adaptation, à la fois à des échelles locales et à des échelles très larges, par des dynamiques adaptatives «à deux vitesses»Environmental drivers, most notably temperature, affect the biology of phyllosphere microorganisms but also induce changes in their population dynamics, even in their evolutionary trajectories. The impact of climate on foliar plant disease epidemics is usually considered in forecasting models to inform management strategies. Such models focus on averages of environmental drivers but disregard both individual variation within populations and the scale and extent of biologically relevant environmental changes. These simplifications are glossing over substantial levels of individual variation that may have important consequences on the capacity of a population to adapt to environmental changes, and thus on the dynamics of epidemics in a fluctuating or changing climate. To examine the range of validity and consequences of these simplifying assumptions, I investigated how individual variation and environmental heterogeneity jointly affect fitness, phenotypic composition and resilience of populations of a foliar pathogen (Zymoseptoria tritici) inhabiting wheat canopies. Three complementary ways of exploration were adopted in this case study. First, an in vitro high-throughput phenotyping framework was developed, validated, and used to characterise the diversity in patterns of thermal responses existing across Z. tritici populations that were sampled over contrasted scales (spatial and seasonal variation of temperature). Second, the spatio-temporal thermal variations encountered in a wheat canopy, considered as a habitat exerting fluctuating selective pressures on these differential thermal sensitivities of individuals, were investigated in depth. Third, the way selection of “thermotypes” (functional groups of individuals displaying a similar thermal sensitivity) occurs and drives dynamics of Z. tritici populations was examined. To this end, both empirical (in vitro, in planta and in natura) and theoretical (in silico) competition experiments were conducted under increasingly complex selective environments. This research work demonstrates that glossing over the natural extent of individual phenotypic diversity in a phyllosphere microbial population and over the heterogeneity of selective pressures – from phyllo- to mesoclimate – leads to underestimate the resilience of this population, and thus its adaptive potential to environmental variations. In doing so, the results of this thesis, at the interface between epidemiology, micrometeorology, and ecology, improve our understanding of how important is individual variation to population dynamics and how environmental heterogeneity allows to maintain population diversity. Finally, this thesis provides insight into how large-scale patterns and local population processes are interlinked and display a “two-tier” adaptive dynamics
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Achebak, El Khadiri Hicham. "Trends in temperature-related mortality in spain: assessing early adaptation to warming climate." Doctoral thesis, Universitat Autònoma de Barcelona, 2021. http://hdl.handle.net/10803/672018.
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Les emissions antropogèniques de gasos d'efecte hivernacle han augmentat les temperatures anuals a Espanya al voltant d'un grau centígrad des de 1980. No obstant això, se sap poc sobre el grau en què la relació entre temperatura i mortalitat humana s'ha vist modificada com a conseqüència del ràpid escalfament del clima. L'objectiu general d'aquesta tesi doctoral és avaluar les tendències recents en el risc i càrrega de mortalitat associada a la calor i al fred, i d'aquesta manera, determinar si hi ha una adaptació per part de la societat espanyola a les conseqüències negatives de l'augment de les temperatures. Per a això, la recerca s'estructura al voltant de tres estudis empírics publicats en revistes acadèmiques, que constitueixen el nucli de la present tesi doctoral. En general, els resultats d'aquests estudis apunten a una reducció en el risc i càrrega de mortalitat associada a les temperatures càlides i fredes durant el període d'estudi 1980-2016. La reducció en l'impacte de la calor sobre la mortalitat podria ser compatible amb una resposta adaptativa que abordi específicament les conseqüències negatives del canvi climàtic. No obstant això, la reducció simultània de l'impacte de les temperatures fredes també posa de relleu la importància dels mecanismes d'adaptació que no estan directament lligats al canvi climàtic, com el desenvolupament socioeconòmic, les millores en els serveis sanitaris i socials, o una major conscienciació sobre els efectes en la salut dels factors ambientals, entre molts altres factors.Las emisiones antropogénicas de gases de efecto invernadero han aumentado las temperaturas anuales en España alrededor de un grado centígrado desde 1980. Sin embargo, se sabe poco sobre el grado en qué la relación entre temperatura y mortalidad humana se ha visto modificada como consecuencia del rápido calentamiento del clima. El objetivo general de esta tesis doctoral es evaluar las tendencias recientes en el riesgo y carga de mortalidad asociada al calor y al frío, y de esta manera, determinar si existe una adaptación por parte de la sociedad española a las consecuencias negativas del aumento de las temperaturas. Para ello, la investigación se estructura en torno a tres estudios empíricos publicados en revistas académicas, que constituyen el núcleo de la presente tesis doctoral. En general, los resultados de estos estudios apuntan a una reducción en el riesgo y carga de mortalidad asociada a las temperaturas cálidas y frías durante el período de estudio 1980-2016. La reducción en el impacto del calor sobre la mortalidad podría ser compatible con una respuesta adaptativa que aborde específicamente las consecuencias negativas del cambio climático. Sin embargo, la reducción simultánea del impacto de las temperaturas frías también pone de relieve la importancia de los mecanismos de adaptación que no están directamente ligados al cambio climático, como el desarrollo socioeconómico, las mejoras en los servicios sanitarios y sociales, o una mayor concienciación sobre los efectos en la salud de los factores ambientales, entre muchos otros factores.
Anthropogenic greenhouse gas emissions have increased annual temperatures in Spain by around one degree Celsius since 1980. However, little is known about the extent to which the association between temperature and human mortality has been modified as a result of the rapidly warming climate. The overarching aim of this PhD thesis is to assess the recent trends in the mortality risk and burden associated with heat and cold, and in this way, have a better understanding of an eventual early adaptation response of the Spanish society to the negative consequences of rising temperatures. For this purpose, the research is structured around three empirical studies published in academic journals, which constitute the core of the present PhD dissertation. Overall, results from these studies point to a reduction in the mortality risk and burden associated with warm and cold temperatures during the period 1980-2016. The reduction in the impact of heat on mortality could be compatible with an adaptive response specifically addressing the negative consequences of climate change. Nevertheless, the simultaneous reduction in the impact of cold temperatures also highlights the importance of the mechanisms of adaptation that are not necessarily associated with climate change, such as socioeconomic development, improvements in health care and social services, or an increase in the awareness of the risks of the environmental factors, among many other factors.
Universitat Autònoma de Barcelona. Programa de Doctorat en Demografia
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Wong, On-Lam Anderson. "Short term and long term physio-biochemical adaptations of the Japanese eel (Anguilla Japonica, Temminck & Schlegel) to temperaturechanges." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1989. http://hub.hku.hk/bib/B31209014.
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Basson, Christine Helene. "Thermal adaptation in the lizard Cordylus oelofseni : physiological and behavioural responses to temperature variation." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/95471.
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Thesis (MSc)--Stellenbosch University, 2013.ENGLISH ABSTRACT: As ectotherms, lizards are particularly vulnerable to changes in the thermal landscape and face extinction risk if they lack the capacity to rapidly adapt or behaviourally mitigate increasingly altered thermal environments. Theoretical models that predict lizards‟ response to climate change often fail to take into account the thermal characteristics of the microenvironment, the ability of lizards to behaviourally buffer climate variation in the habitat and the plastic nature of both behaviour and physiology over ecologically relevant time-scales. Here, I address this major knowledge gap using two separate research chapters in an experimental physiology approach. In Chapter 1, I investigated the temperature-dependence and plasticity of resting metabolic rate, water-loss rate and preferred body temperature of Cordylus oelofseni at several temporal scales (within and between seasons) and incorporated field observations to acquire a better understanding of this species‟ adaptive potential to buffer thermal changes in the habitat. Cordylus oelofseni showed plasticity of both behaviour and physiology in response to thermal acclimation, but relied on distinct strategies depending on the time-scale investigated. These results highlighted the complexity of underlying mechanisms used by these organisms to buffer temperature variation. In Chapter 2, I used an experimental approach to examine the energetic costs of thermoregulation in C. oelofseni and test the cost-benefit model of thermoregulation. This model‟s primary prediction states that lizards should thermoregulate carefully only when the associated costs are low. Using four enclosures that simulated different thermal qualities (temporal and spatial distributions of operative temperatures) in the habitat, I found limited support for the cost-benefit model. Lizards in the low-quality heterogeneous enclosures invested the same energetic effort and thermoregulated with similar overall accuracy as lizards in the high-quality heterogeneous enclosure. The costs incurred were not necessarily energetic, but reflected missed opportunities (e.g. less time to forage), something that, along with important interaction effects with body mass, deserves further attention when testing this model. Together, these results illustrate the importance of incorporating ecological reality at various time and spatial scales in order to make relevant predictions regarding the fate of lizards with projected climate change.
AFRIKAANSE OPSOMMING: As ektotermiese diere, is akkedisse veral sensitief vir veranderinge in die termiese landskap en staar uitsterwingsrisiko in die gesig as hulle nie die vermoë het om vinnig aan te pas of gedragsveranderinge te maak in omgewings wat toenemend verwarm nie. Teoretiese modelle wat akkedisse se reaksie op klimaatsverandering voorspel, neem dikwels nie die termiese eienskappe van die mikro-omgewing, die vermoë van akkedisse om met gedragsveranderinge klimaat variasie in die habitat te buffer en die plastieke aard van beide gedrag en fisiologie oor ekologies relevante tydskale in ag nie. Hier bespreek ek hierdie groot kennisgaping met behulp van twee afsonderlike navorsingshoofstukke in 'n eksperimentele fisiologie benadering. In Hoofstuk 1 het ek ondersoek ingestel na die temperatuur-afhanklikheid en plastisiteit van rustende metaboliese tempo, waterverlies tempo en voorkeur liggaamstemperatuur van Cordylus oelofseni by verskeie tydskale (binne en tussen seisoene) en inkorporeer veld waarnemings om 'n beter begrip te verkry van hierdie spesie se aanpasbare potensiaal om termiese veranderinge in die habitat te buffer. Cordylus oelofseni het plastisiteit van beide gedrag en fisiologie in reaksie op hitte-akklimatisering getoon, maar staatgemaak op verskillende strategieë, afhangende van die tyd-skaal wat ondersoek is. Hierdie resultate beklemtoon die kompleksiteit van die onderliggende meganismes wat gebruik word deur hierdie organisme om temperatuur verandering te buffer. In Hoofstuk 2 het ek 'n eksperimentele benadering gebruik om die energiekoste van termoregulering in C. oelofseni te ondersoek en die kostevoordeel model van termoregulering te toets. Hierdie model se primêre voorspelling verklaar dat akkedisse slegs versigtig moet termoreguleer wanneer die gepaardgaande koste laag is. Deur gebruik te maak van vier afskortings wat verskillende termiese eienskappe gesimuleer het (tyd en ruimtelike verspreiding van operatiewe temperature) in die habitat, het ek beperkte ondersteuning gevind vir die koste-voordeel model. Akkedisse in die lae-gehalte heterogene afskortings het dieselfde energieke moeite belê en getermoreguleer met soortgelyke algehele akkuraatheid as akkedisse in die hoë-gehalte heterogene kamp. Die kostes wat aangegaan is, is nie noodwendig energiek nie, maar weerspieël geleenthede wat gemis is (bv. minder tyd om kos te soek), iets wat, saam met belangrike interaksie effekte met liggaamsmassa, verdere aandag verdien wanneer hierdie model getoets word. Tesame illustreer hierdie resultate die belangrikheid van die integrasie van ekologiese werklikheid op verskillende tyd en ruimtelike skale, om relevante voorspellings oor die lot van akkedisse met geprojekteerde klimaatsverandering te kan maak.
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Schaffer, Joseph F. "Verification and Adaptation of an Infiltration Model for Water at Various Isothermal Temperature Conditions." Digital WPI, 1999. https://digitalcommons.wpi.edu/etd-theses/1061.
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"A series of one dimensional horizontal infiltration experiments were performed to investigate the predictive capabilities of the Kao and Hunt model. By modifying pristine laboratory apparatus, a reasonable range of soil temperatures was achieved. Experiments were run at approximately 5°C, 20°C, and 35°C. Distilled water was used as an infiltrating liquid and silica powder was used as soil. The infiltrating liquid was dispensed into the column at zero pressure head. The results of the experiments show that the model is adaptable to a range of temperature conditions by modifying terms for the liquid effects of the model, viscosity and surface tension. Experimental data and model predictions differed by 30 percent at most. Although the change in the rate of infiltration across the range of temperatures is perceivable, it is small in comparison to the effects caused by heterogeneity encountered in nature. "
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Jamali, Karim Dino. "Interaction of dwarfing genes in wheat (Triticum aestivum L.) and their adaptation to high temperature." Thesis, University of Newcastle Upon Tyne, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315613.
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Gashlan, Hana Mohamed A. "Fatty acid composition and glycerolipid metabolism during temperature adaptation in the marine cyanobacterium Aphanizomenon sp." Thesis, Swansea University, 2000. https://cronfa.swan.ac.uk/Record/cronfa42999.
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The nature and mechanisms of adaptive changes in the fatty acid composition of membrane glycerolipids in laboratory cultures of the marine cyanobacterium Aphanizomenon sp. induced by temperature transitions similar to those experienced by natural population of Aphanizomenon in the Baltic Sea were investigated. At 28° palmitic acid (16:0) predominated (35%) over α-linolenic acid (α-18:3; 23%), whilst in cells grown at 15°, α-18:3 (38%) predominated over 16:0 (25%). Changes in fatty acid composition of the major glycerolipids monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG0, sulfoquinovosyldiacylglycerol (SL) and phosphatidylglycerol (PG) were studied after temperature shifts from 28° to 15° and from 15° to 28°. After lowering the temperature, the level of 16:0 and 18:1 decreased in MGDG, DGDG and SL fractions, whilst the content of 16:3 and α-18:3 increased. In PG however the level of 16:1 and 18:1 increased whilst the level of α-18:3 decreased. After a temperature shift from 15° to 28° the level of 16:0 remained unchanged in MGDG and SL whilst α-18:3 decreased and 16:1 increased. Determination of the positional distribution of fatty acids present in the individual glycerolipid classes using Rhizopus lipase hydrolysis established the predominance of C-18 fatty acids at the sn-1 position and C-16 fatty acids at the sn-2 position; during the adaptation to lower temperature the most prominent change at the sn-1 position was an increase in 18:1, 18:3 and 16:3 levels in MGDG.
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López, Malo María. "Metabolic and molecular adaptation of wine yeasts at low temperature fermentation: strategies for their genetic improvement." Doctoral thesis, Universitat Rovira i Virgili, 2013. http://hdl.handle.net/10803/123828.
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La fermentación a baja temperatura incrementa el perfil aromático del vino. Sin embargo presenta algunos inconvenientes: descenso de la tasa de crecimiento, fermentaciones lentas o con paradas.
Se comparó el metaboloma de una levadura vínica creciendo a 12 ºC y 28 ºC. Las principales diferencias se observaron en el metabolismo lipídico y en la homeostasis redox. Se comparó el metaboloma de levaduras criotolerantes, Saccharomyces bayanus var. uvarum and Saccharomyces kudriavzevii, con el de S. cerevisiae creciendo a 12 ºC Las principales diferencias se encontraron en el metabolismo de la fructosa.
Se analizó la capacidad fermentativa y de crecimiento de cepas mutantes y sobre-expresantes del metabolismo lipídico. El incremento de la dosis génica de los genes PSD1, LCB3 y OLE1mejoraron el crecimiento y la capacidad fermentativa.
Se desarrollaron cepas mejor adaptadas al frío mediante evolución dirigida, se analizaron los cambios moleculares, observándose una inducción de 4 genes de la familia DAN/TIR.Low temperature alcoholic fermentations are becoming more frequent as they enhance wine’s aromatic profile but present some disadvantages: reduced growth rate, long lag phase, sluggish or stuck fermentations. We compared the metabolome of wine yeast growing at 12 ºC and 28 ºC in a synthetic must. The main differences were observed in lipid metabolism and redox homeostasis. We also compared the metabolome of the cryotolerant yeasts, Saccharomyces bayanus var. uvarum and Saccharomyces kudriavzevii, growing at 12 ºC to the metabolome of S. cerevisiae. The main differences were found for fructose metabolism. We also analyzed the growth and fermentation capacity of lipid mutants and overexpressing strains. The increase in gene-dosage of PSD1, LCB3 and OLE1 genes improved both growth and fermentation activity. Finally, we developed cold adapted wine yeast strains by evolutionary engineering, and deciphered the underlying changes, resulting in new strain with up-regulation of 4 genes belonging to DAN/TIR family.
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Bradley, Larry D. "Pressure and temperature effects on bacteriorhodopsin light to dark adaptation studied by near-infrared raman spectroscopy." Honors in the Major Thesis, University of Central Florida, 1994. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/123.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.Bachelors
Arts and Sciences
Physics
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Osborn, Scott Donald. "Adaptive heterothermy in desert mammals." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185449.
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Endothermic homeothermy is a major feature of the adaptive suites of tachymetabolic animals such as mammals and birds. The advantages homeothermy confers on birds and mammals include relative independence from the environment, a stable internal milieu, and possibly the ability to sustain high aerobic activity (Bennett and Ruben 1979). Some mammals in situations of limited water or energy availability, however, depart markedly from homeothermy and instead display patterns of heterothermy. Torpor is a lowering of body temperature (T(b)) to conserve energy and/or water. I studied the energetics of arousal from torpor in two desert pocket mice species. The species differed in warming rates and arousal durations, but used similar amounts of energy to arouse. The smaller species, Perognathus amplus, lost mass more quickly while fasting in the cold, yet waited as long as the larger species, Chaetodipus baileyi, before entering torpor. P. amplus maintained a lower T(b) during topor than C. baileyi. The thermodynamics of arousal indicated that metabolic rate during arousal was a function of T(b) but not ambient temperature (Tₐ), that the animals changed thermal conductance to increase heat gain when Tₐ was greater than T(b), and that Q₁₀ decreased during arousals. In contrast to torpor, adaptive hyperthermia provides desert mammals in dry, hot environments a means to conserve water that would normally be used for evaporative cooling. I modeled the effects of body size on adaptive hyperthermia and discovered that small mammals gain the most in terms of water savings using this strategy, and that small and large mammals can spend larger fractions of the day active than do medium size mammals. I demonstrated that two desert ground squirrel species make use of adaptive hyperthermia during the summer near Tucson, Arizona by following free-ranging squirrels implanted with temperature-sensitive radio transmitters. Ground squirrel T(b) fluctuated almost continuously, ranging from about 35°C to over 42°C, and rarely approached steady state. Of the two species studied, Ammospermophilus harrisii had higher mean T(b), similar maximum T(b), and lower T(b) variability compared to Spermophilus tereticaudus. These results are consistent with the more wide-ranging foraging style of A. harrisii compared to S. tereticaudus.
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Wilches, Ricardo. "Evolution of genes related to temperature adaptation in Drosophila melanogaster as revealed by QTL and population genetics analyses." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-172396.
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The fixation of beneficial variants leaves genomic footprints characterized by a reduction of genetic variation at linked neutral sites and strong, localized allele frequency differentiation among subpopulations. In contrast, for phenotypic evolution the effect of adaptation on the genes controlling the trait is little understood. Theoretical work on polygenic selection suggests that fixations of beneficial alleles (causing selective sweeps) are less likely than small-to-moderate allele frequency shifts among subpopulations. This thesis encompasses three projects in which we have experimentally addressed the issue of selective sweeps vs. allele frequency shifts in the context of polygenic adaptation. We studied three X-linked QTL underlying variation in chill coma recovery time (CCRT), a proxy for cold tolerance, in Drosophila melanogaster from temperate (European) and tropical (African) environments. The analysis of these QTL was performed by means of selective sweep mapping and quantitative complementation tests coupled with expression assays.
While the results of the selective sweep mapping approach identified a gene (CG4491) that is unlikely to be affecting CCRT, quantitative and gene expression analyses revealed two linked candidate genes (brk and CG1677) that appear to differ in their evolutionary histories. We found that the difference in expression of the gene brk between populations affects CCRT variation. Cold tolerant flies from the temperate zone have a lower expression of this gene than cold sensitive flies from the tropics. We found that a likely cause of this difference is variation in a cis-regulatory element in the brk 5’ enhancer region. Sequence variants in this element exhibit moderate frequency differences between populations from temperate and tropical environments, forming two latitudinal clines: one from the equator to the north and another one in opposite direction to the south. In contrast, the other gene within the same QTL (CG1677), which is linked to brk, showed no measurable effect on cold tolerance but is a likely target of strong positive selection leading to a selective sweep in the European population.
These results are consistent with the aforementioned theoretical predictions about footprints of selection in polygenic adaptation. They are also proof of the conceptual bias incurred when identifying candidate genes within a QTL via selective sweep mapping, at least in naturally evolving populations. The challenge for the evolutionary genetics community in the coming years is to develop statistical tools that are as powerful and robust as those already available to map selective sweeps to identify sites in the genome where allele frequency shifts have occurred due to adaptive evolution at the phenotypic level.
Finally, the last section of the results is a report of a new population genetics dataset. It consists of a collection of 80 inbred lines from a natural D. melanogaster population in Sweden and 19 full genome sequences derived from this sample. We hope this material will provide us with further insight into the processes underlying adaptation to novel and stressful environments.
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Audsley, Jennifer M., and jennifer audsley@med monash edu au. "Alternative Approaches In The Preparation And Growth Of Influenza B Vaccine Viruses." RMIT University. Applied Sciences, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080414.141937.
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Influenza B viruses are a significant cause of disease and influenza B antigens are present in all human vaccines. Achieving suitable yields of seed viruses is often difficult for vaccine manufacturers. With influenza A viruses increases in yields have been achieved by the preparation of reassortants between a high-yielding donor strain and an epidemic strain. However, reassortment of influenza B viruses for the preparation of seeds has not been usually undertaken due to the lack suitable donor strains. Such an approach, which formed the basis of this thesis, could improve vaccine yields, lower costs and introduce a further element of predictability to vaccine manufacture. Potential donor strains were prepared from B/Lee/40 (B/Lee) by two approaches involving the selection of stable cold- and high- temperature mutants. Initial passaging was undertaken in specific-pathogen-free (SPF) chicken embryo kidney (CEK) cultures and later passage in SPF embryonated chicken eggs. Both approaches were successful, although a smaller number of viable progeny could be isolated from plaques obtained at 38aC. Potential donor strains, isolated by selection at either 25 or 38aC and plaque-purified in SPF CEK cultures, were tested for haemagglutinin and infectious titre, in comparison with the original parental strain by three methods, and for differences in antigenicity by cross-haemagglutination-inhibition tests. Potential donor strains selected at temperatures of 25aC (C25) and 38aC (H38) produced haemagglutination titres of 320 units/50ÝL and infectivities of 8.57 and 8.39 50% egg infectious doses, respectively, when grown in eggs at the permissive temperature (34aC). Reassorting experiments using the B/Lee-derived potential donor strains C25 and H38 and the epidemic strain, B/Johannesburg/5/99 (B/Johannesburg), showed that the preparation of reassortant progeny with both epidemic strain HA and NA was difficult. Only 1/24 of the resulting reassortants possessed both the HA and NA of the epidemic strain. None of the reassortant progeny produced in reassorting experiments using C25 and H38 and the epidemic strain B/Panama/45/90 (B/Panama) possessed the desired 6:2 gene constellation (i.e. genes for the two surface antigens of the epidemic strain and the remainder from the donor strain). The infectious titre of selected progeny from the reassortment experiments were determined by three methods and compared with their respective epidemic parents. Yields of several influenza B epidemic strains and potential donor strains were measured after growth in Madin-Darby canine kidney (MDCK) cells prepared in serum-containing (SC) and animal- and human-derived protein-free (AHPF) media. Optimal multiplicities of infection were determined for B/Panama, B/Johannesburg and C25 in MDCK cultures grown in SC medium. A series of experiments were then undertaken to determine the maximum virus yields in MDCK cells grown in SC medium, followed by a further experiment using C25, B/Panama, B/Johannesburg, and selected reassortants after preparation in AHPF medium. Cell culture yields from 5/6 viruses grown in MDCK cells prepared in AHPF medium were higher than in cells prepared in SC medium and approached those obtained in eggs.
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Carvalho, Ana Isabel do Carmo Verde de. "Efeito da exposição às temperaturas extremas na população portuguesa - um contributo da epidemiologia." Master's thesis, Faculdade de Ciências Médicas. Universidade Nova de Lisboa, 2008. http://hdl.handle.net/10362/4848.
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Backgroud: O International Panel on Climate Change prevê que o aumento da temperatura média global, até ao ano de 2100, varie entre 1,4 e 5,8ºC desconhecendo-se a
evolução da adaptação da população a esta subida da temperatura. Em Portugal morre-se
mais no Inverno que no Verão. Mas existem evidências de repercussões na mortalidade
atribuíveis ao calor extremo. Este estudo procura conhecer os grupos etários e/ou
populacionais que parecem revelar vulnerabilidade acrescida à exposição a temperaturas extremas e identificar indicadores de saúde apropriados para revelar esses mesmos efeitos. Métodos: Foram analisados dados de internamentos hospitalar e mortalidade por doenças cardiovasculares, respiratórias, renais, efeitos directos do frio e do calor, na população com
75 e mais anos de idade, nos distritos de Beja, Bragança e Faro, nos meses de Janeiro e
Junho. Para os dados de morbilidade o período de análise foi 2002 a 2005 e para os de mortalidade de 2002 a 2004. Os dados meteorológicos analisados corresponderam aos valores da temperatura máxima e percentis da temperatura máxima, nos meses de Janeiro (P10) e Junho (P90). Os excessos de internamentos hospitalares, definidos como os dias em que ocorreram internamentos acima do valor da média mais 2 desvio padrão, foram relacionados com a distribuição das temperaturas extremas (frias abaixo do P10, quentes acima do P90.Os dias com óbitos acima do valor da média foram relacionados com a distribuição das temperaturas extremas (frias abaixo do P10, quentes acima do P90). Os indicadores propostos foram baseados em Odds Ratios e intervalos de confiança que sugeriam as estimativas mais precisas. Resultados: O grupo que revelou maior vulnerabilidade às temperaturas extremas foi o grupo dos 75 e mais anos, com doenças cardiovasculares quando exposto a temperaturas extremas, nos 3 distritos observados.O nº de dias de excesso de óbitos por doenças cardiovasculares relacionados com
temperaturas extremas foi o mais elevado comparado com as restantes causas de morte. O grupo etário dos 75 e mais anos com de doenças respiratórias também é vulnerável, às
temperaturas extremas frias, nos 3 distritos. Verificaram-se dias de excessos de
internamentos hospitalares e óbitos por esta causa de morte, relacionados com a exposição
às temperaturas extremas frias. Em Junho, não se verificou excesso de mortalidade associado à exposição a temperaturas
extremas por esta causa, em qualquer dos distritos analisados. Apenas se verificou a associação entre os dias de ocorrência de internamentos hospitalares por doenças renais e o calor extremo, em Bragança. Conclusões: Foram encontradas associações estatísticas significativas entre dias de
excesso de ocorrência de internamentos hospitalares ou óbitos por causa e exposição a temperaturas extremas frias e quentes possibilitando a identificação de um conjunto de indicadores de saúde ambiental apropriados para monitorizar a evolução dos padrões de morbilidade, mortalidade e susceptibilidade das populações ao longo do tempo.-------------------- Backgroud: International Panel on Climate Change estimates that the rise of mean global temperature varies between 1,4 e 5,8ºC until 2100, with unknowing evolution adaptation of populations. In Portugal we die more in Winter than in Summer time. But there are several evidences of mortality attributable to extreme eat. The proposal of this study is to know the age and/or populations groups that reveal more
vulnerability to exposure to extreme temperature and identifying proper health indicators to reveal those effects. Methods: Data from hospital admissions and mortality caused by cardiovascular, respiratory, renal diseases and direct effects from direct exposure to extreme cold and heat, in population with 75 and more years, in Beja, Bragança and Faro districts, during January and June, were analysed. Analysis period for morbidity data was from 2002 to 2005 and form mortality was 2002 to 2004. Meteorological data analysed were maximum temperature and percentile of maximum
temperature, from January (P10) and June (P90. Relationship between excess of hospital admission, defined as the days that occurred hospital admissions above mean value more 2 standards desviation and distribution of extreme temperatures were established (cold under P10 and heat above P90. Proposal indicators were based on Odds Ratios and confidence intervals, suggesting the most precises estimatives. Results: The most vulnerable group to extreme temperature were people with 75 or more years older with cardiovascular diseases, observed in the 3 districts. Number of days caused by excess cardiovascular mortality and extreme temperature were the most number of days between the other causes. The group with 75 or more years old with respiratory diseases is vulnerable too, especially to cold extreme temperature, in all the 3 districts. There were excess of days of hospital admissions and days with deaths, for this cause relating to extreme cold temperature. In June, does not funded excess of mortality associated to extreme temperature by this
cause in any district of the in observation. Just was found relationship between days of hospital admissions caused by renal diseases
in Bragança in days with extreme heat. Conclusions: Were found statistically significant associations between days of excess of hospital admissions or deaths and exposure to extreme cold and heat temperatures giving the possibility of identifying a core of environmental indicators proper to monitoring patterns
and trends evolutions on morbidity, mortality and susceptibly of populations for a long time.
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Lee, Charles Kai-Wu. "Eurythermalism of a deep-sea symbiosis system from an enzymological aspect." The University of Waikato, 2007. http://hdl.handle.net/10289/2588.
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The recently proposed and experimentally validated Equilibrium Model provides the most detailed description of temperature's effect on enzyme catalytic activity to date. By introducing an equilibrium between Eact, the active form of enzyme, and Einact, a reversibly inactivated form of enzyme, the Equilibrium Model explains apparent enzyme activity loss at high temperatures that cannot be accounted for by irreversible thermal denaturation. The Equilibrium Model describes enzyme behavior in the presence of substrates and under assay conditions; thus its associated parameters, deltaHeq and Teq, may have physiological significance. The Equilibrium Model parameters have been determined for twenty-one enzymes of diverse origins. The results demonstrated the wide applicability of the Equilibrium Model to enzymes of different types and temperature affinity. The study has also established deltaHeq as the first quantitative measure of enzyme eurythermalism and demonstrated the relationship between Teq and optimal growth temperature of organisms. The Equilibrium Model is therefore a useful tool for studying enzyme temperature adaptation and its role in adaptations to thermophily and eurythermalism. Moreover, it potentially enables a description of the originating environment from the properties of the enzymes. The Equilibrium Model has been employed to characterize enzymes isolated from bacterial episymbionts of Alvinella pompejana. A. pompejana inhabits one of the most extreme environments known to science and has been proposed as an extremely eurythermal organism. A metagenomic study of the A. pompejana episymbionts has unveiled new information related to the adaptive and metabolic properties of the bacterial consortium; the availability of metagenomic sequences has also enabled targeted retrieval and heterologous expression of A. pompejana episymbiont genes. By inspecting enzymes derived from the unique episymbiotic microbial consortium intimately associated with A. pompejana, the study has shed light on temperature adaptations in this unique symbiotic relationship. The findings suggested that eurythermal enzymes are one of the mechanisms used by the microbial consortium to achieve its adaptations. By combining metagenomic and enzymological studies, the research described in this thesis has lead to insights on the eurythermalism of a complex microbial system from an enzymological aspect. The findings have enhanced our knowledge on how life adapts to extreme environments, and the validation of the Equilibrium Model as a tool for studying enzyme temperature adaptation paves the way for future studies.
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Sommer, Angela. "Mechanismen und Grenzen der Temperaturanpassung beim Pierwurm Arenicola marina (L.) = Temperature adaptation in the polychaete worm Arenicola marina (L.). mechanisms and limitations /." Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung, 1998. http://www.gbv.de/dms/bs/toc/251247708.pdf.
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Besson, Anne Amelie, and n/a. "Effects of cool temperature on egg incubation, thermoregulation and physiological performance of tuatara (Sphenodon punctatus) : implications for conservation programmes." University of Otago. Department of Zoology, 2009. http://adt.otago.ac.nz./public/adt-NZDU20090713.160643.
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Tuatara (Sphenodon spp.) were once widespread over both the North and the South Islands of New Zealand approximately 1000 years ago but are now restricted to offshore islands due to introduced predators and habitat destruction. The survival of tuatara is now threatened by climate change because of isolation on islands that prevent them from migrating to cooler regions, and by their limited capacity to adapt due to their long life span and low genetic diversity. The thermal suitability of cooler regions for future translocations could be the key for tuatara conservation. The overall aim of the study was to determine the effect of cool temperature on the physiology, behaviour and egg incubation of Cook Strait tuatara (Sphenodon punctatus). As well answering specific questions about tuatara and their adaptation to cool temperature this study aimed at answering general questions about the behavioural and evolutionary ecology of reptiles.
I first compared the preferred body temperature, feeding responses and tolerance to cold temperature of tuatara (Sphenodon punctatus) with three lizard species that inhabit the Otago region of southern New Zealand: Hoplodactylus maculatus, Naultinus gemmeus and Oligosoma maccanni. As well as testing the co-adaptation hypothesis between preferred body temperature and physiological performance of reptiles, I wanted to determine whether tuatara (which are planned to be reintroduced from a warmer site to the Otago region) have similar responses to cool temperature as do Otago lizard species. I found that tuatara show responses to cold temperatures similar to those of lizards from southern New Zealand, suggesting that if tuatara are translocated outside of their geographical range, they are likely to survive.
I then tested if tuatara were capable of modifying their thermoregulatory behaviour if translocated to a cooler region. To do so, I conducted a laboratory experiment in which tuatara were provided with three thermal treatments corresponding to the thermal environments they would experience in their current habitat and the proposed reintroduction site. Contrary to the prediction of the cost-benefit model of thermoregulation, tuatara became active thermoregulators when the thermal quality of the habitat decreased. The results suggest that the model is less applicable to cold-adapted species and that if translocated to cooler regions, tuatara will be able to adjust their thermoregulatory behaviour to their thermal environment.
Tuatara are temperature-dependent sex determination (TSD) reptiles and their translocation to cooler regions could have an dramatic impact on the sex ratio of new populations. To determine if potentially lower incubation temperature would be a limiting factor for the reintroduction of tuatara, I translocated eggs to the proposed reintroduction site. Some tuatara embryos developed at the site (and later hatched in the laboratory), but incubation lasted longer than in natural nests and all hatchlings were female. This trend observed in biased sex ratio might change in the context of climate change as an increase of soil temperature by 3�C would allow the production of males at the proposed site.
The present study demonstrates that the translocation of tuatara further south, outside of their current geographical range, is possible and recommended. Tuatara show similar responses to cool temperatures compared with lizards that live in southern New Zealand, they can also adjust their thermoregulatory behaviour if translocated to cooler habitats, and tuatara embryos could potentially develop successfully in cooler regions. The greatest chance for the future survival of tuatara and TSD species in general, lies in translocation to other locations that are thermally suitable.
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Wilches, Ricardo [Verfasser], and Wolfgang [Akademischer Betreuer] Stephan. "Evolution of genes related to temperature adaptation in Drosophila melanogaster as revealed by QTL and population genetics analyses / Ricardo Wilches. Betreuer: Wolfgang Stephan." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2014. http://d-nb.info/1056876425/34.
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Ferreira, Gabriela da Silva. "Análise da atividade enzimática mitocondrial e mecanismos de adaptação em bovinos submetidos ao estresse pelo calor." Universidade Estadual Paulista (UNESP), 2019. http://hdl.handle.net/11449/180631.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Com aumento global da temperatura, compreender como o metabolismo de bovinos se adapta ao estresse térmico, permitirá selecionar animais melhor adaptados ao aumento da temperatura ambiente. Uma das possibilidades é compreender como cada raça responde a esse efeito ambiente. O trabalho objetivou expor ao sol duas raças distintas de bovinos com diferente resistência ao calor e estudar as alterações no metabolismo mitocondrial e comportamental após a exposição ao sol ou não por 60 dias. Foram analisados 23 animais da raça Angus – susceptível ao calor (12 ao sol e 11 sob sombra) e 25 Nelores – tolerantes ao calor (13 ao sol e 12 sob sombra). Após todos os animais passarem por período de adaptação de 60 dias, foram divididos entre os grupos e analisados os parâmetros ambientais (THI, HLI e AHLU), movimentação (por radiotelemetria), concentrações séricas de testosterona e LH por radioimunoensaio, espessura de tecido adiposo subcutâneo por ultrassonografia e atividade enzimática mitocondrial de músculo esquelético do complexo I (NADH oxidoredutase). A atividade mitocondrial foi avaliada em amostras da musculatura do tríceps braquial colhidas por biópsia periodicamente ao longo do experimento. Os parâmetros ambientais caracterizam o desconforto térmico que os animais foram submetidos, principalmente Angus sol com índice de AHLU muito acima de estresse extremo. Os Angus se movimentaram mais que os Nelore durante o período experimental (p<0,05) e os Nelore se movimentaram mais à noite em comparação ao dia (p<0,05). As concentrações de testosterona aumentaram do período de adaptação para o experimento para ambas as raças e tratamentos. Os animais da raça Nelore apresentaram maior depósito de gordura subcutânea que os Angus. A atividade mitocondrial aumentou significativamente do período de adaptação (P0) para o experimento (P1) e não diferiu durante o experimento entre as raça e os tratamentos. Animais endotérmicos mantidos em altas temperaturas respondem com adaptações metabólicas e comportamentais mediante o estresse exposto. Os Nelore se movimentam mais à noite quando a temperatura é mais amena e os Angus durante o dia à procura de conforto térmico. A atividade mitocondrial é aumentada devido a alta demanda de ATP provavelmente em repercussão da necessidade de sinalizar biogênese mitocondrial, reparação celular, movimentação e níveis aumentados de testosterona.
Cattle farmers are suffering challenges in the animal breeding, consequence of the global increase of the temperature. Understanding how the homeothermic metabolism adapts to the thermal stress, allows the selection of better adapted animals to the of the environmental temperature increase. One of those possibilities is to understand each breed reacts to this ambient effect. The work aimed to expose in the sun two different bovine breeds that have different heat resistance and evaluate the mitochondrial metabolism and behavioral changes during sun exposure. Twenty three Angus - susceptible to heat (12 in the sun and 11 in shadow) and 25 Nellore - heat tolerant (13 in the sun and 12 in shadow) animals were analyzed. After all the animals went through a 60 days adaptation period, the animals were sorted composing the groups and analyzed the environmental parameters, movement (by radiotelemetry) subcutaneous fat thickeness and mitochondrial enzymatic activity from squelectical muscle samples.The activity mitochondria were evaluated by the enzymatic reaction of the compound I (NADH oxidoreductase) in muscular tissue samples that were collected periodically during the experiment. The environmental parameters characterize the thermal discomfort that the animals were subjected to, mainly Angus sun with AHLU index well above extreme stress. The Angus moved more than the Nellore during the experimental period (p <0.05) and the Nellore moved more at night compared to the day (p <0.05). Testosterone concentrations increased from the adaptation period to the experimental for both breeds and treatments. The animals of the Nelore breed presented greater subcutaneous fat deposition than the Angus. Enzymatic mitochondrial activity increased significantly from the adaptation period (P0) to the experiment (P1) and did not differ during the experiment between breed and treatments. Homeothermic animals kept at high temperatures respond with metabolic and behavioral adaptations through exposed stress. The Nelore move more at night when the temperature is milder and the Angus during the day looking for thermal comfort. Mitochondrial activity is increased due to high ATP demand probably in repercussion of the need to signal mitochondrial biogenesis, cell repair, movement and increased levels of testosterone.
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Sonesson, Johan. "Early testing of adaptedness to temperature and water availability in Pinus sylvestris and Picea abies /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2000. http://epsilon.slu.se/avh/2000/91-576-5897-8.pdf.
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Hemmer-Brepson, Claire. "Effets de la température sur la balance oxydative de vertébrés ectothermes aquatiques à différentes échelles spatio-temporelles et conséquences sur les traits d'histoire de vie : modèle poisson." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4354.
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Le réchauffement climatique a des conséquences sur la phénologie, les aires de répartition et la taille des organismes. Cependant, les processus physiologiques sous-jacents à ces phénomènes restent peu connus. Les ectothermes dont le métabolisme est positivement corrélé à la température pourraient montrer, sous réchauffement climatique, une production accrue d'espèces réactives de l'oxygène (ERO). Ces ERO ont été depuis quelques décennies définis comme l'un des mécanismes physiologiques sous-jacents aux stratégies d'histoire de vie. Dans cette thèse, nous avons exploré la physiologie oxydative de poissons dans des contextes thermiques variés et ses conséquences sur la gestion des traits d'histoire de vie. Nos approches expérimentales et de terrains menées sur Oryzias latipes, Perca fluviatilis & Rutilus rutilus, nous ont permis de montrer ces liens. Ces résultats sont à compléter, notamment sur le terrain où de nombreux effets confondants ont rendu les conclusions difficilesGlobal warming affects the phenology, range and body-sizes of species. However, the underlying physiological processes remain poorly understood. Ectothermic organisms, whose metabolism is positively correlated with temperature, would show an increase in reactive oxygen species (ROS) production under global warming. These ROS have been proposed to be one of the physiological triggers of the life history strategies. In this thesis, we explored the oxidative physiology of fish in different warming contexts and their effects on life-history traits. Our experimental and field approaches on Oryzias latipes, Perca fluviatilis & Rutilus rutilus, allowed us highlight these links. However, further studies are necessary, especially in natura where many confounding effects have made conclusions difficult
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Westerlund, T. (Tarja). "Thermal, circulatory, and neuromuscular responses to whole-body cryotherapy." Doctoral thesis, University of Oulu, 2009. http://urn.fi/urn:isbn:9789514290435.
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Abstract
The purpose of this study was to examine thermal (body temperature, thermal sensation and comfort ratings), circulatory (blood pressure, heart rate variability) and neuromuscular performance responses to whole-body cryotherapy (WBC, -110 °C).
Altogether 66 healthy subjects were exposed to WBC for two minutes. The acute and long-term changes were examined, when the subjects were exposed to WBC three times a week during three months.
Skin temperatures decreased very rapidly during WBC, but remained such a high level that there was no risk for frostbites. The effects on rectal temperature were minimal. Repeated exposures to WBC were mostly well tolerated and comfortable and the subjects became habituated at an early stage of trials. WBC increased both systolic (24 mmHg) and diastolic (5 mmHg) blood pressures temporarily. Adaptation of blood pressure was not found during three months. The acute cooling-related increase in high-frequency power of RR-intervals indicated an increase in cardiac parasympathetic modulation, but after repeated WBC the increase was attenuated. The repeated WBC exposure-related increase in resting low frequency power of RR-intervals resembles the response observed related to exercise training. There are signs of neuromuscular adaptation, especially in dynamic performance. A single WBC decreased flight time in drop-jump exercise, but after repeated WBC these changes were almost vanished. This adaptation was confirmed by the change of the activity of the agonist muscle, which increased more and the change of the activity of antagonist muscle, which increased less/did not change after repeated WBC indicating reduced co-contraction and thus, neuromuscular adaptation.
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Sawicka, Joanna Elżbieta [Verfasser], Bo Barker [Akademischer Betreuer] Jørgensen, and Bernhard [Akademischer Betreuer] Fuchs. "Arctic to tropic - adaptation and response of anaerobic microorganisms to temperature effects in marine sediments / Joanna Elżbieta Sawicka. Gutachter: Bo Barker Jørgensen ; Bernhard Fuchs. Betreuer: Bo Barker Jørgensen." Bremen : Staats- und Universitätsbibliothek Bremen, 2011. http://d-nb.info/1071898086/34.
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El, Amil Rola. "Effet de l’hôte et de la température sur la structure de la population de Puccinia striiformis f. sp. tritici, agent de la rouille jaune du blé au Moyen Orient." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112236/document.
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L’adaptation des pathogènes à leurs hôtes et aux variations climatiques, particulièrement à la température est étudiée sur l’agent pathogène biotrophe obligatoire responsable de la rouille jaune du blé, Puccinia striiformis f. sp. tritici (Pst) au Moyen Orient. Cette étude s’est déroulée au Liban et en Syrie situés dans le berceau de la région de domestication du blé. Des gènes de résistance spécifique ont été postulés au stade plantule pour 87 lignées élites du programme d’amélioration de l’ICARDA,28 cultivars Libanais, et 23 landraces Libanaises en utilisant 11 pathotypes français disponibles à l’INRA-BIOGER. Un seul gène et une combinaison de gènes ont été postulés dans les lignées elites. Neuf gènes de résistance ont été identifiés dans les lignées élites ; plus de génotypes résistants figuraient parmi les lignées issues du programme d’amélioration. Les landraces sont les plus sensibles mais ont montré une ségrégation de réaction résistance parmi les plants sensibles.Pour la structuration de population pathogène du Liban et de la Syrie, un échantillonnage a été fait dans les deux pays sur du blé tendre, du blé dur et des repousses durant 2010-2011. Six isolats Libanais et 48 isolats Syriens ont été pathotypés avec une gamme de 43 hôtes différentiels. 275 échantillons ont été génotypés avec 20 marqueurs SSR. La population était clonale malgré avec la présence de l’hôte secondaire Berberis sp. dans la région, toutefois un nombre élevé de 50 MLG est observé était pour une population clonale. La présence de la race invasive PstS1/PstS2 caractérise cette région. Le profil de virulence Vr2, 6, 7, 9, 27 est le plus fréquent et typique du groupe génétique Méditerranéen (Bahri et al., 2009). La virulence Vr8 n’est pas fixée dans la population malgré sa présence dans la race invasive décrite depuis l’an 2000 (Milus et al., 2009). L’adaptation de la rouille jaune à la température a été décrite par Milus et al. (2009) et Mboup et al. (2012). Notre étude d’adaptation à la température a été faite sur un échantillon de 26 isolats provenant de zones froides et chaudes avec 4 isolats de référence. Nous avons testé deux paramètres d’agressivité, efficacité d’infection et période de latence sous quatre différents régimes de température (Chaud versus froid pour période de rosée et période d’incubation). Les isolats diffèrent pour leur réponse aux variations de température. Quelques isolats montrent une efficacité d’infection et une courte période de latence sous les différents régimes, d’autres sont efficaces au froid mais pas au chaud et vice versa. Pour l’efficacité d’infection, il n’y a pas d’adaptation mais par contre pour la période de latence on montre une adaptation à la température des isolats de la zone chaude ayant une efficacité d’infection. La température chaude de rosée a retardé la période de latence mais ce phénomène a été moins marqué pour les isolats d’origine chaude quand c’est incubé au chaud. Cette étude a montré que la population est clonale avec un haut nombre de pathotypes. Le germplasme n’est pas diversifié avec des gènes de résistance contre la rouille jaune. L’adaptation de l’agent de la rouille jaune à la température parmi les isolats testés a été décrite pour la période de latence pour les isolats provenant d’origine chaudeThe adaptation of fungal pathogen to its hosts and to the climate variation, in particular to the temperature, was investigated on wheat stripe (yellow) rust, caused by the biotroph fungus Puccinia striiformis f. sp. tritici (Pst) in the Middle East, focusing on Lebanon and Syria. This disease is a major problem for the crop in the region. Specific resistance genes were postulated in 138 wheat genotypes including elite lines, grown varieties and local landraces, using an array of 11 French pathotypes. Resistance gene diversity for yellow rust in wheat elite lines was higher than in current, commercial varieties grown in Lebanon, with nine Yr genes detected singly or in combination. Some varieties were resistant to all tested pathotypes and might provide interesting sources of resistance. Most of the Lebanese landraces were susceptible but also heterogeneous by their number of plants susceptible and resistant to a specific pathotype in a same landrace.A field survey was conducted in Lebanon and Syria in 2010-2011 and 275 Pst isolates were collected. The pathogen population was genotyped with 20 microsatellite markers and was found to be clonal, although the alternate host Berberis libanotica is present in the region. The dominant multilocus genotype shared similarity with the new invasive strain PstS1/PstS2 dispersed worldwide since 2000. The population was clonal with 10 pathotypes detected in Lebanon and Syria. 50 MLGs were detected considered high for clonal population. The virulence profiles combining Vr2, Vr6, Vr7, Vr9, and Vr27 are typical of the Mediterranean area according to group (Bahri et al., 2009) and corresponded to the worldwide invasive pathotype described since 2000 (Milus et al., 2009). The Vr8 was not fixed in this population, whereas this virulence is frequent in the Mediterranean genetic group (Bahri et al., 2009).Recently Pst strains have been described for adaptation to warm temperature (Milus et al., 2009; Mboup et al., 2012). The question of temperature adaptation in this study was whether the strains adapted to warm temperature are found in few clones of invasive strains or if they are selected in different pathogen genotypes locally under specific climate conditions. We selected 26 Pst isolates from the Middle East, 13 isolates from warm and 13 isolates from cold areas. We assessed their infection efficiency and latent period under four temperature regimes (high and warm temperature for the spore penetration phase, and high and warm temperature for the latency period). The isolates differed for the thermal aptitude for infection efficiency and latent period, but no clear relationship was established between the climate of the origin location of the isolate and its thermal aptitude. Some isolates were able to infect at high temperature but had long latency at high temperature and vice versa, some isolates had low infection efficiency and short latent period at high temperature, and few isolates were efficient either at high temperature or cold temperature for infection efficiency. Latency period showed pattern of local adaptation. Warm dew temperatures retarded sporulation, but this effect was far less marked for isolates from warm climates when incubated under warm conditions.This study provides details about probable effective yellow rust genes present in different genotypes and the prevalent pathotypes in the region. Moreover, the thermal aptitude for infection efficiency and latent period of some isolates under contrasting temperature will help us to build a better integrated disease management in the highlight of global warming
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Erdal, Ufuk Goksin. "The Effects of Temperatures on System Performance and Bacterial Community Structure in a Biological Phosphorus Removal System." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/26384.
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It is generally accepted that a decrease in temperature causes the rates of chemical and biochemical reactions to slow down, usually resulting in poorer performance of biological wastewater treatment systems. Despite this, early researchers repeatedly showed that excess biological phosphorus removal (EBPR) was more efficient at colder temperatures. Recent studies, however, have demonstrated that the reaction rates of EBPR processes decrease with temperature in accordance with Arrheniusâ Law, resulting in an apparent contradiction in the literature. The objective of this study was to investigate the EBPR temperature controversy. The experimental systems used were two, lab-scale UCT configuration plants fed with acetate as the sole volatile fatty acid (VFA) source. The results showed that EBPR systems do perform more efficiently at colder temperatures, i.e., at 5oC compared to 20oC. The reason for better system performance was determined to be related to reduced competition for substrate in the non-oxic zones that results in an increased population of phosphate accumulating organisms (PAOs) relative to non-PAOs and, therefore, greater EBPR efficiency even though the reaction rates are slower. The proliferation of PAOs relative to non-PAOs at cold temperature indicates that some of the PAOs are psychrophilic, i.e., they have alternate biochemical pathways that give them a competitive advantage over bacteria dependent upon glycogen metabolism. The activated sludge acclimated to 20oC had relatively high polyhydroxyvalerate (PHV) and glycogen contents relative to sludge acclimated to 5oC. It was initially hypothized that there is a significant competition between PAO and glycogen accumulating organisms (GAOs) at 20oC and cold temperature (5oC) nearly eliminates this competition in favor of the PAOs. A series of batch test experiments revealed that despite similar acetate utilization by the sludges grown at the two temperatures nearly 30% less PHA was produced by the sludge taken from the 20oC reactor, indicating that GAOs were a small fraction of the population at 20oC. Transmission electron microscopy pictures showed that the biomass acclimated to 20oC had a much more diverse bacterial population than the biomass acclimated to 5oC. However, no GAO population was detected in electron microscopy samples under any temperature conditions. The decreased P removal efficiency at 20oC was then attributed to the presence of fermentative or other non poly-P bacteria that are capable of utilizing substrate under anaerobic conditions.
PHA production greatly increased at 5oC, whereas glycogen metabolism substantially reduced. Even though glycogen is an essential requirement for EBPR mechanism, the EBPR microorganisms have the ability to adapt their metabolic pathways to environmental conditions and greatly reduce their need for glycogen. It is apperant that cold temperature inhibits some of the key enzymes in glycogen metabolism resulting in lower glycogen accumulation that in turn increases the EBPR performance. Therefore temperature not only exerts selective pressure on the dominant population but also alters the metabolic pathways of the EBPR process. Increased glycogen accumulation, as observed in this study at 20oC, may not be related to GAO proliferation as suggested by Filipe et al. (2001) instead it may be related to EBPR bacteria to efficiently use glycogen metabolism. Current models (Brdjanovic et al. 1997; Filipe et al. 2002) consider that GAO metabolism is an integral part of EBPR metabolism and the performance of EBPR processes depends on PAO/GAO fraction in the EBPR system. No GAO proliferation was observed even the A/O process was operated without P addition for more than 3 weeks at 10oC. Therefore such important concept should be further investigated before it is included in EBPR models.
EBPR stoichiometry was presumed to be insensitive to temperatures (Brdjanovic et al. 1997). However, observed stoichiometric values of PHA storage per unit glycogen utilization and PHA utilization per unit glycogen rephlenishment were quite different at different temperatures. Temperature, therefore, not only affects the kinetics of EBPR systems but also affects the EBPR stoichiometry.
Most prokaryotic cells have the ability to alter their cellular membrane fatty acid composition as temperature decreases to counteract the adverse effects of temperature on membrane fluidity (Becker et al., 1996). This unique ability is known as â homeoviscous adaptationâ . In this study, homeoviscous adaptation by EBPR activated sludge was investigated for a series of temperatures ranging from 20oC to 5oC using one of the lab scale EBPR systems. The fatty acid analysis results showed that the unsaturated to saturated fatty acid ratio increased from 1.40 to 3.61 as temperature dropped from 20 to 5oC. The increased cis-9-hexadecanoic acid (C16:1) at 5oC strongly indicated the presence of homeoviscous adaptation in the EBPR bacterial community. Thus the cell membranes of the EBPR community were still in a fluid state, and solute transport and proton motive force mechanisms were operable even at 5oC. It was concluded that loss of EBPR performance at low temperatures, as reported by McClintock et al. (1992) was not related to the physical state of the cellular membranes, but was probably caused by unsuitable operational conditions.
Even though the transport of volatile fatty acids (e.g. acetate) is an integral part of EBPR biochemistry and stoichiometry, this important concept has been ignored. Fleet (1997) concluded that acetate entry into bacterial cells in EBPR sludge was simple passive diffusion based upon the results of a single study (Baronofsky et al. 1984). However, this study showed that neither acetate nor propionate can cross the cell membrane via simple passive diffusion. The existence of apparent saturation curves when the substrate uptake rates (acetate and propionate) were plotted against the substrate concentrations suggested that transport of volatile fatty acids obey facilitated or active transport.
Following from the above results, an investigation of the impacts of operational conditions such as low solids retention time (SRT), presence of electron acceptors in the non-oxic zones, low anaerobic detention time, and lack of acclimation was performed. The results showed that the â critical, i.e., wash-outâ SRT increased as temperature decreased, but if the biomass was permitted to acclimate to the lower temperature, a major population shift would occur which would increase the capacity of the system for phosphorus (P) removal. When the 5 oC sludge was allowed to acclimate at a relatively high SRT (18 d), the systemâ s P-removal capacity greatly surpassed that of the 20 oC system. The decrease in EBPR performance because of the presence of nitrates in the non-oxic zones was determined to be greater than what would be predicted based on accepted stoichiometry.Ph. D.
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Wirtssohn, Sarah Kaarina. "Stimulus- and context-dependent temporal filtering in the auditory pathway of the locust." Doctoral thesis, Humboldt-Universität zu Berlin, Lebenswissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17396.
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Die zeitliche Filterung von sensorischem Input ist entscheidend für das Erkennen vieler Stimuli. Auditorische Neurone führen dazu mehrere Verarbeitungsschritte und Signaltransformationen durch, u.a. durch zeitliche Integration, zeitliche Auflösung und Selektion eines zeitlichen Merkmals. Um zu testen ob zeitliche Filterung von Stimuluseigenschaften (Intensität) oder Kontext (Temperatur) abhängt untersuchte ich Neurone in der Hörbahn der Wanderheuschrecke. Zuerst untersuchte ich zeitliche Integration in Rezeptoren und Interneuronen. Zeitverlauf und Ausmaß der Integration waren Neuronen-spezifisch. Während periphere Neurone die akustische Energie integrierten, unterschied sich die zeitliche Integration der Interneuronentypen stark, was eine spezifische zeitliche Filterung ermöglicht. Die Analyse postsynaptischer Potentiale deckte presynaptische und intrinsische Mechanismen der Integration auf, was darauf hindeutet, dass Unterschiede zwischen Neuronen wahrscheinlich auf Typ-spezifischer Verarbeitung beruhen. Zweitens erforschte ich die neuronale Antwort auf den zweiten Stimulus in einem Stimuluspaar mit einem Interstimulus-Intervall von wenigen Millisekunden. Die Veränderung der Antwort auf den zweiten im Vergleich zum ersten Stimulus zeigt den Effekt von akuter, kurzfristiger Adaptation und ist ein Maß für die maximale zeitliche Auflösung. In der sensorischen Peripherie trat moderate Adaptation auf, deren Einfluss exponentiell abfiel. Viele Interneurone zeigten dagegen nicht-lineare Effekte, wie die Unterdrückung oder Verstärkung der Antwort auf den zweiten Stimulus. Drittens testete ich den Effekt von Temperatur auf zeitliche Filterung. Die Selektivität von Interneuronen für zeitliche Stimulusmerkmale wurde bei wechselnden Temperaturen untersucht. Mit steigender Temperatur präferierten Neurone ein zeitlich komprimiertes Merkmal. Diese temperaturabhängige Veränderung könnte zur Temperatur-Kopplung von Sender und Empfänger bei den wechselwarmen Heuschrecken beitragen.Temporal filtering of sensory input is crucial for the recognition of many sensory stimuli. Auditory neurons perform various computations and signal transformations to accomplish temporal filtering of acoustic input, comprising temporal integration, temporal resolution and temporal feature selection. To test whether temporal filtering processes within a neuron type depend on stimulus features, such as intensity, and on context, such as temperature, I conducted neurophysiological recordings from neurons in the auditory pathway of migratory locusts. First, I examined temporal integration in receptors and interneurons. The time course and extent of integration of subthreshold acoustic stimuli were neuronspecific. While peripheral sensory neurons acted as energy integrators, interneurons showed different temporal integration profiles, enabling neuron-specific temporal filtering. The analysis of postsynaptic potentials elucidated implemented mechanisms, suggesting that temporal integration is based on neuron-specific presynaptic and neuron-intrinsic computations. Second, I studied the response recovery of receptors and interneurons to the second stimulus in a stimulus pair, separated by a few milliseconds. This revealed the effect of acute, short-term adaptation and thus indicated the maximal temporal resolution of these neurons. In the sensory periphery response recovery was shaped by moderate adaptation and an exponential recovery. In many interneurons non-linear effects occurred, comprising a suppression of the response to the second stimulus and a response gain. Third, I tested the effect of temperature on temporal filtering. Temporal feature selectivity of interneurons was examined at cold and warm temperatures. With increasing temperature, the neurons preferred a temporally compressed feature. Temperature-dependent changes in temporal feature selectivity might thus contribute to temperature coupling of the sender and the receiver of the poikilothermic grasshoppers.
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Matumba, Tshifhiwa Given. "Genetics and thermal biology of littorinid snails of the genera Afrolittorina, Echinolittorina and Littoraria (Gastropoda: Littorinidae) from temperate, subtropical and tropical regions." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1001953.
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With the anticipated effects of climate change due to global warming, there is concern over how animals, especially ectotherms, will respond to or tolerate extreme and fluctuating environmental temperature stress. Littorinid snails are intertidal ectotherms that live high on the shore where they experience both extreme and variable conditions of temperature and desiccation stress, and are believed to live close to their tolerance limits. This study investigated the thermal biology of littorinid snails of the genera Afrolittorina, Echinolittorina and Littoraria from temperate, subtropical and tropical regions in South Africa and Brunei Darussalam using thermal tolerance, heart function, and proteome approaches. The effects of conditions, such as rate of change in temperature, acclimation, heat shock, season and starvation were also tested. In addition, the evolutionary relationships and genetic diversity between and within the South African Afrolittorina spp. were investigated using mitochondrial and nuclear markers. Genetic results confirmed that these are two distinct species, with the brown to black A. knysnaensis predominant in the cool-temperate region of South Africa and the pale blue-grey A. africana in the subtropical region. There was low genetic variation and differentiation within each species, suggesting high gene flow among populations as a result of the effects of ocean currents on the dispersal of their planktotrophic larvae. Tests using exposure to high temperatures revealed differences in the thermal tolerances, heart performance and protein profiles of species from different latitudes, regions and zones on the shore. Thermal tolerance conformed to expectations, with clear, statistically significant trends from high tolerance in subtropical species to lower tolerance in temperate species. However, for Afrolittorina spp., there were no significant differences in the thermal tolerances of conspecifics from different regions, though there was a significant difference in thermal tolerance between juveniles and adults. Overall, adults of all species showed higher thermal tolerances than juveniles. Although lethal temperatures for these species were higher in summer than winter, laboratory acclimation had no effect on heat coma temperatures. All species showed some regulation of heart rate, with a degree of independence of heart rate from temperature across mid-range temperatures. The tropical species showed quick induction and good regulation of heart rate followed by the subtropical and temperate species, which displayed mixed responses including regulation, partial regulation and lack of regulation. Overall, tropical Echinolittorina spp. showed good regulation, while the subtropical E. natalensis and Littoraria glabrata exhibited a mixture of partial regulation and regulation. The subtropical/temperate Afrolittorina spp. showed high individual variability, some animals exhibiting regulation, while others did not. These effects seem to be largely phylogenetically determined as there were no differences in the heart rate responses of Afrolittorina spp. from different regions. The temperatures at which heart rate became independent of temperature (thermoneutral zone) were within the range experienced under natural conditions. In addition, there were differences in Arrhenius breakpoint and endpoint temperatures, showing a trend from higher in tropical animals to lower for temperate animals. Conditions such as acclimation, heat shock and starvation had little or no effect on heart performance. However, a slow increase in temperature induced good regulation of heart rate with noticeable shifts of breakpoints and endpoints for Afrolittorina spp. Lastly, there were differences in the proteome responses between and within Afrolittorina spp. as a function of species, size and treatment. Although both large and small A. knysnaensis had a greater number of protein spots in their proteome than A. africana (though the difference was not significant), the later showed significantly higher differential expression of certain proteins following heat stress. In addition, juveniles of both species displayed greater numbers of protein spots in their proteome than adults. The results indicate a difference in the physiological and biochemical responses (i.e. adaptations) of these snails to temperature, and this seems to relate to differences in biogeography, phylogeny, species identity and ecology. The ability to regulate heart rate is phylogenetically determined, while thresholds and lethal limits correspond to biogeography and species ecology. The proteome seems to correspond to species ecology. The results also indicate that these littorinids can tolerate high temperature stress and in this respect they are well suited to life in the intertidal zones or habitats where temperature and other stresses or conditions are extreme and can change abruptly. However, the limited ability of these snails to acclimate to different temperatures suggests that they are already living close to their tolerance limits with small safety margins or narrow thermal windows and so may be vulnerable to small rises in substratum temperature and/or solar radiation.
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Stattin, Eva. "Root freezing tolerance and storability of Scots pine and Norway spruce seedlings /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5639-8.pdf.
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Nardin, Maxime. "Ajustement biologique du mélèze aux variations environnementales le long d’un gradient altitudinal : approche microdensitométrique de la réponse au climat." Thesis, Orléans, 2013. http://www.theses.fr/2013ORLE2071/document.
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La forte variation climatique, notamment de la température qui est associée à la distribution altitudinale de certains peuplements d’arbres forestiers peut induire des pressions de sélection divergentes favorisant l’expression de phénotypes différents en fonction de l’altitude. Cette thèse a pour objectif de déterminer si des adaptations locales existent et peuvent être mises en évidence dans un peuplement de mélèze (Larix decidua Mill.) distribué le long d’un gradient altitudinal situé dans les Alpes françaises, à proximité de Briançon. Quatre placettes d’environ 200 mélèzes ont été délimitées à 2300 m, 2000 m, 1700 m et 1350 m d’altitude le long de ce gradient. Une variabilité phénotypique significative a été observée entre ces niveaux altitudinaux pour la plupart des caractères étudiés : circonférence, hauteur de l’arbre, pourcentage d’aubier ainsi que pour toutes les variables microdensitométriques de cernes sauf une (la largeur de cerne). Une analyse de génétique des populations utilisant des marqueurs microsatellites a mis en évidence une faible influence de la dérive génétique sur la diversité génétique et une forte intensité de flux de gènes entre les différents niveaux altitudinaux étudiés. La différenciation génétique inter-altitudes a été estimée à l’aide d’une approche in-situ basée sur les données phénotypiques seules (PST) et comparée à la différenciation observée à l’aide des marqueurs microsatellites (FST). Cette analyse indique que l’hypothèse d’adaptations locales avec l’altitude peut être raisonnablement avancée pour les caractères de hauteur, circonférence, pourcentage d’aubier et densité du bois initial. Au contraire, l’adaptation locale n’apparait pas comme une hypothèse acceptable pour les caractères de largeur de cerne, surface de cerne, largeur du bois final et densité du bois finalThe strong climatic variation, in particular the temperature variation, which is associated with the altitudinal distribution of certain stands of forest trees, can induce different divergent selection pressure favoring altitude-dependent phenotype expression. The aim of the present thesis is to determine if local adaptation exists and can be identified in an European larch stand (Larix decidua Mill.) distributed along an altitudinal gradient located in the French Alps near Briançon. four plots of about 200 larches were delimited at 2300 m, 2000 m, 1700 m and 1350 m along this altitudinal gradient. A significant phenotypic variability was observed between these altitudinal levels for most characters studied: circumference, tree height, percentage of sapwood and for all the annual-ring microdensity variables except one (ring width). A population genetics analysis using microsatellite markers showed a small effect of genetic drift on the genetic diversity but an intensive gene flow between the altitudinal levels studied. The inter-altitudinal genetic differentiation was estimated using an in-situ approach based on phenotypic data only (PST) and compared with the differentiation observed by means of microsatellite markers (FST). This analysis indicates that the assumption of local adaptation with altitude can be reasonably proposed for the characters of height, circumference, percentage of sapwood and earlywood density. On the contrary, the local adaptation does not appear to be an acceptable assumption concerning characters such as ring width, ring surface area, latewood width and latewood density
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Lourenço, Flávia Mendes dos Santos. "Metodologia do teste de envelhecimento acelerado em sementes de tomilho (Thymus vulgaris L.) e mini tomate (Solanum lycopersicum var. cerasiforme)." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/153260.
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A utilização de testes de vigor, que sejam eficientes no diagnóstico da qualidade das sementes, é de vital importância no sucesso da agricultura. Nesse sentido, a utilização de metodologias que sejam mais adequadas à determinadas espécies é uma ferramenta importante para ser utilizada nos testes de vigor, visando realizar uma avaliação apurada da qualidade das sementes. Assim, objetivou-se estudar se as variações na realização do teste de envelhecimento acelerado, em termos de tempo de exposição e temperatura, realizado na forma tradicional ou em solução salina, resultaria numa combinação eficiente para avaliar a qualidade fisiológica de sementes de tomilho (Thymus vulgaris L.) e mini tomate (Solanum lycopersicum var. cerasiforme). Foi utilizado o delineamento inteiramente casualizado com os tratamentos obtidos da combinação temperaturas (36, 38, 40 e 42 ºC) x tempo de exposição (24, 36, 48 e 72 horas) x procedimentos (tradicional e solução salina), com quatro repetições para cada lote. As médias foram comparadas pelo teste de Tukey a 5% de probabilidade. Determinou-se também o coeficiente de correlação simples (r) entre os resultados dos testes de envelhecimento acelerado e o teste de emergência de plântulas em substrato. Tanto o tempo de exposição como a temperatura, foram fatores que afetaram o desempenho das sementes, de modo geral reduzindo-o com o aumento da temperatura. O uso da solução salina, permitiu a utilização de determinada temperatura por maior espaço de tempo, sem reduzir drasticamente os resultados.
The use of vigor tests, which are efficient in the diagnosis of seed quality, is of vital importance in the success of agriculture. In this sense, the use of methodologies, which are more appropriate to certain species, is an important tool to be used in the vigor tests, aiming at an accurate evaluation of the seeds quality. The aim of this study was to study whether the variations in the performance of the accelerated aging test, in terms of exposure time and temperature, in the traditional form or in saline solution, would result in an efficient combination to evaluate the physiological quality of thyme seeds (Thymus vulgaris L.) and tiny tomato (Solanum lycopersicum var. cerasiforme). It was used a completely randomized design with the treatments obtained from the combination of temperatures (36, 38, 40 and 42 ºC) x exposure time (24, 36, 48 and 72 hours) x procedure (traditional and saline solution) repetitions for each batch. The averages were compared by the Tukey test at 5% probability. The simple correlation coefficient (r) between the accelerated aging test results and the emergence test of substrate seedlings was also determined. Both the exposure time and temperature were factors that affected seed performance, generally reducing it with increasing temperature. The use of saline allowed the use of a certain temperature for a longer period, without drastically reducing the results.
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Camut, Lucie. "Rôle des gibbérellines dans l’adaptation des plantes à la disponibilité en azote." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAJ109.
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Les gibbérellines (GAs) sont des phytohormones régulant divers aspects de la croissance et du développement de la plante en réponse aux signaux endogènes et exogènes. Au niveau moléculaire, les GAs stimulent la dégradation des protéines DELLA, répresseurs nucléaires de croissance. L’azote (N), macronutriment essentiel au développement de la plante, représente un des facteurs les plus limitant pour la productivité agricole. Le nitrate (NO3-), principale source de N pour les plantes cultivées, est une molécule soluble dont la disponibilité varie dans l’espace et le temps. Depuis la Révolution Verte des années 1960, l’application d’engrais azotés et l’utilisation de variétés de céréales semi-naines (altérées dans leurs réponses aux GAs) à forts rendements ont permis d’augmenter significativement la productivité agricole. Récemment, il a été rapporté que des transporteurs NO3 - appartenant à la famille des NPF (NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER FAMILY) étaient capables de transporter des GAs. Malgré les liens historiques et scientifiques établis entre les GAs et le NO3-, peu d’études se sont intéressées à l’effet du nitrate sur la biosynthèse, le transport et la signalisation GA chez les plantes. A l’aide d’approches génétiques, moléculaires et biochimiques réalisées chez Arabidopsis et le bl, ce travail de thèse démontre que le nitrate augmente la production et le transport acropète de GA12 (un intermédiaire de biosynthèse de GAs) et en conséquence, stimule la dégradation des répresseurs DELLAs. La diminution de l’abondance des DELLAs active la division cellulaire et donc la croissance de la plante. Par ailleurs, à l’aide de micro-greffes et de tests d’import de GAs réalisés dans des oocytes de Xenopus laevis, nous montrons que NPF2.12 et NPF2.13 facilitent le transport basipète de GA12 et du nitrate. Enfin, nous montrons que le transport acropète de GA12 est accru en réponse à une élévation de la température ambiante. Pris dans leur ensemble, ces résultats révèlent que la biosynthèse et le transport de GAs sont finement régulés en réponse à la disponibilité en nitrate et aux fluctuations de la température, permettant une croissance adaptée et optimale de la planteThe phytohormones gibberellins (GAs) regulate major aspects of plant growth and development in response to endogenous and exogenous signals. GAs promote growth by stimulating the degradation of nuclear growth repressing DELLA proteins. Nitrogen (N), a macronutrient essential for plant development, is one of the most limiting factors for agricultural productivity. Nitrate (NO3-) represents the main N source for cultivated plants but its availability fluctuates in both time and space due to its high solubility. Since the Green Revolution in the 1960’s, the use of N-fertilizers associated with high-yielding semi-dwarf cereal varieties, altered in GA responses, led to impressive yield increases. Recently, it has been reported that some NO 3 - transporters belonging to the NPF family (NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER FAMILY), were able to transport GAs. Despite these observations, the effect of nitrate on GA biosynthesis, transport and signaling pathway is still unknown. Using genetics, molecular and biochemical approaches performed in Arabidopsis and wheat, this thesis work demonstrates that nitrate activates GA biosynthesis and GA12 transport (an inactive GA precursor), and as a consequence, DELLA protein degradation. The reduction in DELLA abundance increases cell division rate and thus plant growth. Moreover, through micrograftings and GA import assays in Xenopus laevis oocytes, we show that NPF2.12 and NPF2.13 facilitate the basipetal transport of GA12 and nitrate. Finally, we show that GA12 transport is enhanced by a small elevation of the ambient temperature. Altogether, these results reveal that GA biosynthesis and transport are tightly regulated in response to nitrate availability and temperature changes, enabling adaptive and optimal growth of the plant
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Kusi, Joseph, and Ying Li. "Climate Change Impacts: Heat-Related Mortality Projections and Population Adaptive Responses in United States." Digital Commons @ East Tennessee State University, 2015. https://dc.etsu.edu/etsu-works/26.
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We miss summer time during winter especially when it snows heavily resulting in cancelation of classes but we turn to ignore high temperature and its associated health impacts during summer. Several studies have shown that high temperatures during summer are associated with morbidity and mortality in many cities in the United States over the past decade. Gradual increase in temperature over the past years raises public health concerns about the impacts of heat on human health in future and the role of adaptation. Our study aimed at assessing future heat-related mortality due to climate change in the United States. We hypothesized that incidence of premature death will increase with future temperature rise and population adaptation will reduce the mortality rate. We reviewed research articles on temperature-related premature death. The literature search was limited to studies conducted in United States and seven studies which demonstrated positive association between temperature and premature death were selected for this study. We predicted future high temperature-related mortality using BenMap benefit model designed to estimate 2015 Appalachian Student Research Forum Page 111 air pollution impacts on public health. Based on the selected studies, BenMap model projected 2020-2050 temperature scenario using modeled daily mean apparent temperature to estimate future heat-related mortality. Our results showed that high temperatures would cause an increase in heat-related mortality and adaptation would minimize the effects of climate change as people get used to high temperatures. The outcome of our study confirms the positive association between high temperature and mortality which emphasizes the need for policy makers to take appropriate actions such as greenhouse gas emission reduction to protect public health.
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Masroor, Waliullah. "Coping with salinity and temperature changes : a focus on the gill response in European sea bass Dicentrarchus labrax." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTG008/document.
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Le loup ou bar européen effectue une partie de son cycle de vie dans les lagunes et estuaires, des eaux de transitions caractérisées par des fluctuations environnementales plus marquées qu’en milieu marin. Les mécanismes d’acclimatation à la salinité à des températures plus élevées qu’en milieu marin sont encore relativement inexplorés. Dans cette étude, des juvéniles de loup ont été préacclimatés pendant deux semaines à l’eau de mer (EM) à 18 °C (eau tempérée) ou à 24 °C (eau chaude) puis transférés soit dans l’eau douce (ED) soit dans l’EM aux deux températures testées. À 24 °C, les loups parviennent à maintenir leur pression osmotique sanguine relativement constante, quelle que soit la salinité testée. En revanche, la hausse de température affecte significativement différents traits physiologiques liés à l’osmorégulation, la régulation acido- basique, l’excrétion azotée et la production de mucus. Cette étude a notamment montré qu’une acclimatation thermique à 24 °C modifie la structure morphologique de la branchie et induit un déséquilibre de la balance ionique sanguine. Ce déséquilibre concerne particulièrement les ions Na+ et a pour conséquence une diminution du ratio Na+/Cl- plasmatique, pouvant être symptomatique d’une acidose sanguine. Après transfert en douce, une augmentation moins importante de la densité des ionocytes branchiaux et de l’activité de la pompe Na+/K+ ATPase a été observée à 24 °C comparé à 18 °C. De plus, certains transporteurs ioniques jouant un rôle clé dans l’absorption ionique en eau douce n’ont pas été induits au niveau transcriptionnel à 24 °C. Cela suggère une capacité réduite des poissons de passer d’un épithélium branchial hypo-osmorégulateur vers un épithélium hyper-osmorégulateur lors d’un transfert en eau douce à 24 °C vs 18 °C. Au niveau moléculaire, la hausse de température a affecté l’expression de plusieurs transporteurs ioniques branchiaux, notamment en EM. À 24 °C, la surexpression de transporteurs liés au transport de proton H+ pourrait être le signe d’un déséquilibre acido- basique. De plus, l’induction de transporteurs d’ammonium pourrait indiquer un besoin accru d’excréter de l’azote par voie branchiale, potentiellement lié à un métabolisme plus élevé en eau chaude. L’expression des gènes codant pour la protéine chaperonne HSP90 a été fortement affectée par la hausse de température et dans une moindre mesure par la dessalure. Pour finir, l’analyse des mucocytes suggère que la production de mucus pourrait être induite en réponse au stress thermique. Ce type d’étude fonctionnelle sur l’acclimatation à différents régimes de température permet d’apporter des éléments de compréhension pour pouvoir prédire les réponses des téléostéens face aux conséquences du changement globalThe European sea bass Dicentrarchus labrax undertakes seasonal migrations to estuaries and lagoons that are characterized by fluctuations in environmental conditions. It is unclear to what extent salinity acclimation mechanisms are affected at temperatures higher than in the sea, as usually encountered in transitional waters in spring and summer. In this study, juvenile sea bass were pre-acclimated to seawater (SW) at 18 °C (temperate) or 24 °C (warm) for two weeks and then transferred to either fresh water (FW) or SW at the considered temperatures. We have shown that sea bass are able to efficiently maintain blood osmolality at 24 °C at both salinities. However, temperature increase induced significant changes regarding several physiological traits related to osmoregulation, acid-base regulation, ammonia excretion and mucus production. This study showed that thermal acclimation at 24 °C affects gill morphology through gill remodeling and whole-organism ion balance. Plasma Na+ levels seemed to be particularly affected leading to decreased plasma Na+/Cl- ratio in warm conditions, suggesting a blood acidosis. Following FW transfer, the major effects observed were a lower increase in the density of branchial ionocytes and in Na+/K+-ATPase activity at 24 °C compared to 18 °C. Moreover, several key ion transporters involved in ion uptake were not transcriptionally induced following FW transfer at 24 °C. These data suggest a less effective capacity to switch from hypo-to hyper-osmoregulation after FW transfer when fish are exposed to higher temperature. At the molecular level, the temperature increase affected the expression of several branchial transporters, notably in SW. At 24 °C, higher expression of transporters linked to H+ transport might be linked to an acid-base imbalance. Moreover, the induction of ammonia-transporting channels might also indicate increased need for nitrogen excretion, potentially due to enhanced metabolism in warm conditions. Molecular chaperones HSP90 expression was strongly affected by temperature increase and to a lesser extent by salinity decrease. Finally, gill goblet cells analysis suggested that mucus production is increased in response to thermal stress. This study and additional functional studies investigating different temperature regimes provide insights on the effect of increased temperatures on fish responses and may help to predict how teleost will face the consequences of global change
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Artigaud, Sébastien. "Approche intégrative de la réponse d'un organisme marin face au changement climatique : la coquille Saint-Jacques Pecten maximus et les stress thermique et hypoxique." Thesis, Brest, 2013. http://www.theses.fr/2013BRES0078/document.
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Les écosystèmes côtiers sont parmi les plus vulnérables aux changements globaux actuels, qui entraînent notamment une augmentation de la température de l'eau, ainsi que de la fréquence des épisodes hypoxiques. La coquille Saint-Jacques, Pecten maximus, est une espèce subtidale évoluant à des profondeurs de 2 à 210 m. Malgré son intérêt commercial et un intérêt écologique majeur, cette espèce n'a fait l'objet que de peu d'études au niveau moléculaire. L'objectif de cette thèse était de caractériser les mécanismes moléculaires régissant l'acclimatation de cette espèce aux contraintes thermique et hypoxique. Nous avons dans un premier temps caractérisé les modifications d'expression des gènes/protéines, par des approches transcriptomiques (RNAseq) et protéomiques (2-DE), dans un tissu, le manteau, d'animaux exposés à une contrainte thermique prolongée (56 jours). Nous avons ainsi pu identifier les voies majeures de régulation (eg., AP-1), les grandes fonctions (eg., cytosquelette) et processus (eg., apoptose) impliqués dans la réponse, mais également d'observer les grandes orientations du métabolisme (eg., dégradation des lipides de réserve). La réponse des organismes à l'hypoxie dépend de leur manière de gérer les faibles teneurs en oxygène. Nous avons d'abord, par une approche comparative avec une espèce intertidale, la moule (Mytilus spp.), caractérisée la réponse physiologique de la coquille Saint-Jacques à l'hypoxie. Nous avons pu ainsi déterminer ses paramètres d'oxyregulation, plus particulièrement son Point critique en 02 (Pc02). Le développement d'une approche protéomique, couplant l'effet de la température et de l'hypoxie, nous a ensuite permis d'identifier plusieurs protéines (CK2, GLN, etc.) potentiellement impliquées dans la réponse au niveau moléculaire. Enfin, dans l'optique de mieux comprendre la physiologie particulière de ces mollusques dans leur environnement naturel, nous avons comparé les signatures protéomiques de deux populations de P. maximus évoluant dans des écosystèmes contrastés, i.e. en limite nord- (Norvège) et au centre- (Brest) de l'aire de répartition de l'espèce. Les résultats suggèrent des différences majeures entre les deux populations au niveau du cytosquelette. En conclusion, ce travail ouvre des perspectives nouvelles pour la compréhension des mécanismes moléculaires régissant l'adaptation des mollusques aux contraintes thermiques et hypoxiques, deux stress particulièrement importants pour les organismes marins dans le contexte du changement globalCoasts are among the most vulnerable ecosystems to the ongoing global changes, which result in increased water temperatures and frequencies of hypoxic episodes. The great scallop, Pecten maximus, is a subtidal species living at depths of 2-210 m. In spite of its commercial and major ecological values, only few studies at the molecular level were performed on this species. This thesis aimed at characterizing the molecular mechanisms implied in acclimation of this species to thermal and hypoxia stresses. We first characterized the changes of expression of the genes / proteins in response to a long-term thermal stress (56 days), by using both a transcriptomic- (RNAseq) and a proteomic- (2-DE based) approaches, in the mantle tissue of scallops. This allowed us to identify key regulatory pathways (eg., AP-1), the major functions (eg., cytoskeleton) and processes (eg., apoptosis) involved in the response, but also to observe the main orientations of metabolism (eg., degradation of lipid reserves). The response of organisms to hypoxia depends on how they cope with low oxygen availability. Therefore, we first carried out a comparative approach with an intertidal species, the mussel (Mytilus spp.) to characterize the physiological response of P. maximus to hypoxia. Of note, we could determine its oxyregulatory parameters, particularly its critical point in 02 (Pc02). Then, coupling the effects of temperature and of hypoxia, we developed a proteomic approach that allowed us to identify several proteins (CK2, GLN, etc.) potentially involved in the response at the molecular level. Finally, in an effort to better understand the particular physiology of these mollusks in their natural environment, we compared the proteomic signatures of two populations of P. maximus living in highly contrasted ecosystems, ie in the northern limit- (Norway) and the center- (Brest) of the biogeographical distribution of this species. The results suggest major differences between the two populations, especially at the cytoskeleton level. In all, this work opens new avenues for understanding the molecular mechanisms governing the adaptation of mollusks to heat and hypoxia, two stresses that will most probably greatly influence the lifestyle of marine organisms and populations in future years
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JASZAY, THIERRY. "Electrochimie en milieu aqueux a haute temperature et sous pression des materiaux passivables. Adaptation des techniques stationnaires et non stationnaires. Application au titane en milieu chlorure et au nickel, allie ou non, en milieu faiblement ionise des generateurs de vapeur." Nantes, 1991. http://www.theses.fr/1991NANT2026.
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Ce travail a pour objet l'etude du comportement electrochimique de materiaux industriels confrontes a un environnement aqueux a temperature et pression elevees. Il traite notamment du nickel, de ses alliages utilises dans les generateurs de vapeur et du titane, employe, par exemple, dans les evaporateurs. L'utilisation des methodes electrochimiques dans ces conditions particulieres a conduit a la realisation de deux dispositifs specifiques capables, par les solutions techniques adoptees (inertie chimique des autoclaves, exploitation d'une reference interne: electrode dynamique a hydrogene, electrode tournante, maitrise de la phase,. . . ), d'assurer, jusqu'a 300c et 150 bar, une information aussi sure et complete que celle obtenue dans des conditions habituelles de temperature et de pression. Ainsi, l'acces aux courants stationnaires et a l'impedance electrochimique permet d'avancer les elements d'une modelisation de la dissolution et de la passivation du titane en milieu chlorure, dans laquelle la formation de l'oxyde tio2 tient une place importante. Sur la base de ce resultat, un mecanisme propose pour le nickel active en milieu basique faiblement ionise avec une incidence particuliere de l'oxyde nio est applique a certains alliages, notamment l'alliage 800. Le role predominant du nickel sur la dissolution de ces alliages permet de situer les risques d'une exploitation en eau chaude pressurisee
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Breton, Solène. "Relation entre le métabolisme lipidique membranaire et l’adaptation à la température chez les picocyanobactéries marines du genre Synechococcus." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS503.
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Les picocyanobactéries marines sont les plus petits organismes photosynthétiques, mais aussi les plus abondants sur Terre, assurant près de 20% de la production primaire océanique. Parmi elles, les Synechococcus marins présentent une large distribution latitudinale qui peut s’expliquer par la spécialisation physiologique de lignées phylogénétiques le long du gradient latitudinal de température du globe (i.e. écotypes de température). Pour ces cellules phototrophes, la régulation de la fluidité des membranes, où se situent les complexes photosynthétiques, est absolument essentielle pour la survie de la cellule à différentes températures. Cependant, très peu de données sont disponibles sur la composition lipidique des membranes et sa régulation chez les cyanobactéries marines. Mon travail de thèse a consisté en une étude de thermophysiologie comparée de souches représentatives des clades dominants les communautés naturelles de Synechococcus dans les océans, habitant différentes niches thermiques. Nous avons montré que les différents écotypes de température ont des preferenda thermiques distincts et ajustent leur appareil photosynthétique en fonction de la température de croissance. Une étude de lipidomique a permis de mettre en évidence les spécificités membranaires de ces cyanobactéries marines. De plus, cette étude montre qu’en utilisant une trentaine d’espèces moléculaires de lipides, les écotypes de températures utilisent des stratégies de thermorégulation différentes basées sur l’activité différentielle d’enzymes lipide-désaturases. Mon travail de thèse suggère ainsi que la régulation de la fluidité membranaire a représenté un verrou physiologique pour la colonisation de différentes niches thermiques par les Synechococcus marins durant leur microdiversification en écotypes au cours de l’évolutionMarine picocyanobacteria are the smallest, but also the most abundant photosynthetic organisms on Earth, responsible for nearly 20% of oceanic primary production. Among them, marine Synechococcus display a wide latitudinal distribution that is underpinned by the physiological specialization of phylogenetic lineages along the latitudinal gradient of temperature (i.e. temperature ecotypes). For these photosynthetic cells, the regulation of the membrane fluidity, where the photosynthetic complexes are located, is essential for the cell survival at different temperatures. However, very little data is available on the lipid composition of membranes and its thermoregulation in marine cyanobacteria. My PhD thesis is a comparative thermophysiology study of strains representative of the major clades of the natural communities in the oceans, inhabiting different thermal niches. We showed that the different temperature ecotypes have distinct thermal preferenda and adjust their photosynthetic apparatus depending on the growth temperature. A lipidomic study allowed evidencing the membrane specificities of these marine cyanobacteria. In addition, this study shows that, using nearly 30 molecular species of membrane lipids, the temperature ecotypes have implemented different thermoregulation strategies, which are based on the differential activities of lipid desaturase enzymes. My thesis work suggests that the regulation of membrane fluidity has been an important matter for the colonization of different thermal niches by marine Synechococcus during their evolutionary ecotypic microdiversification
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Li, Ying, and Joseph Kusi. "Projecting Future Heat-Related Mortality in the United States under Global Climate Change." Digital Commons @ East Tennessee State University, 2015. https://dc.etsu.edu/etsu-works/18.
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Global climate change is anticipated to raise the overall temperatures and is likely to increase future mortality attributable to heat. Predicting future health consequences of higher temperatures at the regional, national and global level based on historical temperature-mortality relationships can be challenging due in part to the uncertainties in the location-specific temperature-mortality relationship, the heat threshold, and how populations will adapt or acclimatize. This study reviews published estimates of the warm season temperature-mortality relationships around the world and explores the heterogeneity in terms of the magnitude of the relationship and the threshold. We also investigate the potential effects of adaptation and acclimatization on the estimates of excess heat-related deaths based on empirical evidence, and propose a method that can be used in future projections to address the uncertainties. This study contributes to the literature of projecting the future public health burden of heat-related effects, which provides valuable information to climate policy decision making.
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Bennani-Kabchi, Naïma. "Etude des variations saisonnieres de facteurs nutritionnels, hormonaux et metaboliques chez un rongeur desertique, le merion (meriones shawi)." Clermont-Ferrand 2, 1988. http://www.theses.fr/1988CLF2E407.
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Bendia, Amanda Gonçalves. "A vida microbiana em um vulcão antártico: diversidade e adaptação procariótica na Ilha Deception." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/42/42132/tde-11052017-134917/.
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Vulcões ativos na Antártica contrastam com a paisagem predominantemente gelada do continente. Eles fornecem condições únicas capazes de selecionar uma grande variedade de adaptações microbianas. A Ilha Deception localiza-se na região da Península Antártica e difere de outros vulcões antárticos especialmente pela influência marinha e temperaturas mais elevadas. Foram coletadas amostras de sedimentos associados a fumarolas e geleiras em dois sítios geotermais de Deception, com temperaturas variando entre 0°C a 98°C. Diferentes técnicas independentes de cultivo foram empregadas com o intuito de entender como as comunidades microbianas respondem as variações ambientais extremas produzidas pela atividade vulcânica. Os resultados indicaram que a co-ocorrência de arqueias hipertermófilas e suas adaptações com micro-organismos metabolicamente diversos adaptados a regiões geladas representa uma estrutura de comunidades única para ecossistemas antárticos. Este trabalho forneceu dados ineditos sobre questoes centrais de diversidade e adaptacao microbiana a ambientes geotermais polares.Active volcanoes in Antarctica contrast with the predominately icy landscape. They harbor unique conditions capable to select an extreme range of microbial adaptations. Deception Island is located in the Antarctic Peninsula region and differs from other Antarctic volcanoes specially by its higher temperatures and marine influence. We collected sediment samples associated to active fumaroles and glaciers on two geothermal sites of Deception Island, with temperatures ranging from 0°C to 98°C. Different cultivation-indepedent techniques were used to understand how microbial communities respond to extreme environmental variations produced by volcanic activity. The results indicate that co-occurrence of hyperthermophiles and their specific adaptations with metabolically diverse cold-adapted micro-organisms represents a unique community structure for antarctic ecosystems. This study provided primordial data on central questions about microbial diversity and adaptation to polar geothermal environments.
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Poser, Christophe. "Influence de la température sur la phénologie de la canne à sucre : conséquences sur la phase d'implantation de la culture dans les Hauts de La Réunion." Thesis, La Réunion, 2013. http://www.theses.fr/2013LARE0030/document.
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Cette étude s'intéresse aux effets de la température sur le développement de la canne à sucre et le potentiel d'expansion de cette culture au sein de nouvelles zones géographiques. En particulier, elle vise à caractériser les stades de développement de la plante durant lesquels les basses températures agissent afin d'extrapoler des zones géographiques d'adaptation. Un travail plus particulier est engagé sur l'effet des basses températures en condition d'altitude tropicales dans Les Hauts de La Réunion. L'implantation en cycle de plantation est identifiée comme une étape très importante pour les cultures de canne, et pour la culture dans les Hauts en particulier, car elle conditionne non seulement la date de première récolte et son niveau mais elle a un impact sur le cycle de repousse. Les expérimentations ont lieu à la fois en milieu contrôlé (chambre climatique et serre) et en conditions réelles (champs à différentes altitudes). Une étude méthodologique sur la qualité du matériel végétal est réalisée pour valider les conditions d'expérimentation. Cette étude montre que des expérimentations de débourrement de bourgeons peuvent être réalisées avec des boutures d'un seul bourgeon, de taille réduite. Les comparaisons de débourrement à différentes températures nécessitent d'utiliser des boutures triées, saines, et homogènes, c'est-à-dire provenant de la partie médiane de la tige-mère. Les bourgeons de la partie supérieure (entrenœuds non consolidés à croissance non terminée) et ceux issus de la base de la plante devront être écartés. L'influence de la température est quantifiée sur différentes variétés lors de la phase de débourrement-levée, puis au cours des stades de développement suivants jusqu'à la fermeture du couvert végétal. La température influence considérablement sur le processus de débourrement. Le modèle thermique élaboré, bien que limité à une gamme de températures, prédit de façon satisfaisante la levée à température constante et permet de quantifier les différences variétales observées. Les expérimentations au champ révèlent des différences dans les dynamiques d'émission et de croissance des tiges et de mise en place de la surface foliaire, non seulement entre sites d'altitude différente mais aussi entre variétés. La température joue un rôle majeur dans cette différenciation. De plus, selon le processus étudié, le classement des variétés suivant leurs performances n'est pas strictement identique d'un site à l'autre. Ce constat révèle l'intérêt d'approfondir l'étude sur la période d'installation du feuillage en conditions climatiques variées. Le modèle de débourrement-levée développé au cours de cette étude a permis d'identifier des indicateurs pour évaluer la capacité d'adaptation de différentes variétés de canne à sucre. Associés à une base de données météorologique géolocalisée, ces derniers mettent en évidence l'importance de la température seuil dans la capacité d'adaptation des variétés à différentes zones géographiques. Les méthodes et outils élaborés au cours de cette thèse ont d'ores et déjà des retombées pour accompagner les outils traditionnels de sélection variétale à La Réunion et sont extrapolables dans des zones à températures plus fraîches. Ces retombées pourraient s'accroître avec la mise au point de nouveaux itinéraires techniques. Enfin, la poursuite des travaux cartographiques, comme outils d'étude du potentiel d'implantation des cultures dans les Hauts, constitue également un axe prometteur pour la valorisation des acquis de cette thèseThis thesis is centered on the effects of temperature on sugarcane development and its potential for geographical expansion under low temperatures in high-altitude tropical conditions. In the highlands of Reunion Island (les Hauts), the duration of the germination, in planting years, affects the date and the level of the first harvest, as well as the sugarcane yield in the following ratoon crop cycle. Trials took place in climate chambers, greenhouses and fields at different temperatures and altitudes. A preliminary study validates the conditions governing the experimentation: bud bursts can be studied through single, healthy, single bud cuttings that are taken from the middle section of the mature stem. Temperature considerably influences the primary tiller germination and emergence stages. The thermal model that was developed satisfactorily predicts bursting at a constant temperature and allows for the quantification of observed varietal differences. Field trials reveal a disparity in the production and growth dynamics of leaves and stems according to locations and varieties. Temperature influences this differentiation. Among the indicators that were elaborated, the duration for the seedling of half the population, when applied to a climatic database, allows one to define geographical zones and time periods conducive to the introduction of sugarcane according to its variety. The methods presented herein can be used in varietal selection for all zones where cold temperature limits the spread of crops. Results could be used for the development of new cultural practices or for further studies in geo-referenced agronomic zoning