Iodine is a biophilic element with one natural long-lived isotope, 129I (t1/2= 15.6 million years), and one stable isotope, 127I. The inventory of 129I in surface environments has been overwhelmed by anthropogenic releases over the past 50 years. The objective of this study is to utilize the elevated concentration and biophilic nature of 129I and the isotopic ratio of iodine (129I/127I) as a tracer of water mass movement and organic matter. Additionally, the significantly elevated values of 129I/127I could provide a geochronometer, similar to the way 14C is used, particularly for terrestrial organic matter that is less than 50 years old. A series of laboratory experiments and field investigations were carried out to characterize the dominant chemical forms of dissolved iodine, i.e., iodide (I-), iodate (IO 3-), and organic iodine (DOI) in natural waters. Sensitive methods were developed for the analysis of nanomolar quantities of 127I species in a variety of environmental systems using high performance liquid chromatography (HPLC) and an organic iodine decomposition technique, dehydrohalogenation. The potential use of 129I/127I as a hydrological tracer was evaluated through measurements of 129I and 127I, which were carried out in wells in the artificially recharged ground water basin of Orange County, California. Literature values of aquifer ages based on 3H/3He and δ18O tracer data, as well as time-series data of chloride and Santa Ana River flow rates over the past decade were compared to values for 129I and 127I. The iodine isotopes demonstrated a conservative behavior in these aquifers, suggesting that the observed variations of these isotopes reflect past river flow conditions during the time of recharge. The feasibility of using 129I/127I ratios to trace terrestrial organic matter across an estuary was tested. A novel analytical technique to determine 129I/127I ratios in DOI was developed for this investigation. The results of a Galveston Bay transect clearly show that 129I/127I ratios in DOI can remain elevated up to salinity of about 15, but that 129I/127I values of inorganic iodine species do not show any trend with change in salinity gradient due to fast isotopic and chemical equilibration in the estuarine waters.

The goal of this inductive study was to identify factors that facilitate and inhibit binational collaboration in the recovery of endangered species in the northern Mexico borderlands, focusing on the Mexican wolf (Canis lupus baileyi). A conceptual model was developed using qualitative techniques, providing the basis for design of a mail survey. The target population included participants with experience in recovery efforts for over a dozen species at risk in the region. Long interviews were recorded with 44 participants from Mexico and the United States. Thematic hierarchical analysis was used to develop a conceptual model of how interviewees talked about factors influencing binational collaboration. Issues were classified in five thematic clusters: project, organization, people, resources, culture/history. The survey was used to conduct a needs assessment, measuring respondents' attitudes about the relative priority of issues identified in the conceptual model. High priority needs were identified from each thematic cluster: (a) equitable participation in project design and implementation, (b) continuity of personnel, (c) coordination of federal, state and local efforts, (d) increased funding, managed with accountability, and (e) exchange visits to facilitate understanding of diverse perspectives. Responses to almost half the survey items indicated accord among the sample of respondents, providing a basis for shared common ground. The nature of discord was within the range of "manageable", with no clear polarization of attitudes measured. This exploratory data analysis suggested that the structure of the conceptual model developed from the Mexican wolf case study was generally a valid basis for future deductive analysis and reflection by practitioners. For 82% of 22 statements of need, priorities of participants in the Mexican wolf recovery efforts did not differ significantly from other respondents. Nationality (of respondents) significantly affected priority rankings for only 18% of the need statements. Significant effects of five demographic variables indicated that interactive effects should be examined in future multivariate analyses to determine how respondents' attitudes on issues related to priority rankings. Recommendations were provided for a more efficient and effective approach to collaborative problem-solving, engaging reflective practitioners from the private and public sectors in principled negotiation processes to better understand diverse perspectives.

The goal of my dissertation was to describe the dynamics of a group of Houston toads located at the Griffith League Ranch (GLR), Bastrop County, Texas. My research included using statistical modeling to predict activity and abundance, mark-recapture techniques to estimate survivorship, and simulation modeling to explore the impacts of the difference in age at first reproduction and to project the future dynamics of the population at the GLR. From 2001 – 2005, 225 individual Houston toads (199 M : 26 F) were captured using two methods: breeding pond surveys and drift fences. Houston toads were neither caught equally among capture methods, nor across years. Toad activity was mostly confined within their breeding season, and activity was not continuous. A logistic regression indicated activity depended on time of year, mean precipitation, mean minimum daily temperature, and mean percent lunation as well as two-way interactions with moon-phase and other variables. Abundance depended on time of year, current precipitation, minimum temperature, and two-way interactions between time of year and the other two variables. Twenty-one of the 199 males (10.5%) and no females were recaptured among years. The probability of male survival was estimated using program MARK. Eight of 16 candidate models were supported and all but one contained precipitation as a covariate, indicating precipitation is important for Houston toad survival. Survivorship estimates varied from 0.1 to 0.41. The sex ratio was significantly male-biased. The odds of catching females in traps were 3.5 greater than capturing females in a pond, while the odds of capturing males in a trap were 0.28 compared to ponds. Results from a simulation model indicated the sex ratio is biased because of the difference in maturation times between males and females, coupled with high juvenile mortality. Results from an individual-based, spatially-explicit, stochastic simulation model, indicated a relatively low probability (~ 0.013) of B. houstonensis going extinct at the GLR within the next 10 years. Emergent properties of the model were similar to results observed in the field or reported in the literature. The model also identified that dispersal of Houston toads should be a future research priority.

Le facteur de transcription NF-κB joue un rôle majeur dans lorchestration de nombreux processus biologiques, tels que les réponses immunitaires innée et adaptative, la division cellulaire, lapoptose et le développement. Le NF-κB est activé en réponse à un grand nombre de stimuli, comme les cytokines pro-inflammatoires, les agents viraux et bactériens et la stimulation antigénique des cellules du système immunitaire. Il peut être aussi activé dans des conditions de stress oxydant, par exemple après une exposition à des concentrations physiologiques (de lordre du µM) de peroxyde dhydrogène (H2O2). Au début de ce travail, le mécanisme conduisant à lactivation du NF-κB par le stress oxydant était mal connu et sujet à maintes controverses, ce qui nous a poussé à investiguer cette voie plus avant. Dans une première partie, nous nous sommes attachés à étudier le mécanisme dactivation du NF-κB dans des lymphocytes T soumis à un stress oxydant. Les cellules du système immunitaire sont en effet très sensibles à lenvironnement redox, et sont fréquemment en contact avec des espèces réactives de loxygène libérées par les cellules phagocytaires (monocytes/macrophages et neutrophiles) lors dune réponse inflammatoire. Comme le NF-κB est une protéine cruciale pour le développement et lhoméostasie des lymphocytes T, létude de sa modulation lors dun stress oxydant savère particulièrement importante. Nous avons pu mettre en évidence une activation importante du facteur de transcription lors dun traitement oxydant, ainsi quune dégradation presque compète de linhibiteur IκBα. Létude approfondie du mécanisme menant à cette dégradation a mis au jour un mécanisme dactivation tout à fait inédit, impliquant lactivation du complexe IKK via lintervention de lInositol Phosphatase SHIP-1. Dans cette première partie, nous avons également mis en évidence le rôle crucial de la protéine SHIP-1 dans la protection des lymphocytes T contre lapoptose induite par le stress oxydant, ce qui en fait une protéine clé dans la lhoméostasie des lymphocytes T. Dans un second temps, nous nous sommes intéressés au mécanisme influençant la fixation du NF-κB à lADN. Nous avons pu démontrer le rôle important de la protéine IKKα comme déterminant la fixation du NF-κB aux promoteurs de certains gènes, mettant ainsi au jour un mode daction inconnu pour cette protéine. Ce rôle est dautant plus intéressant quil est spécifique, ce qui pourrait déboucher sur des applications thérapeutiques intéressantes.

Les termites forment un groupe animal important en milieu tropical, où leur richesse spécifique est plus élevée que dans n’importe quel autre écosystème. Ils se nourrissent de matière organique végétale à différent état de décomposition, du bois dur à la matière organique minérale du le sol. Cette diversification du régime alimentaire ne se produit que chez les Termitidae, parfois appelés « termites supérieurs », alors que les autres familles se nourrissent exclusivement de bois ou d’herbe. Les termites humivores sont extrêmement abondants en Amérique du Sud et en Afrique tropicale, mais sont relativement peu étudiés par rapport aux termites xylophages. C’est particulièrement vrai pour le groupe Anoplotermes, qui représente le groupe de termites le moins bien connu. Ce travail vise à faire la lumière sur l’écologie et la diversité de ce groupe strictement humivore, et comprend les sections suivantes : (1) Des échantillonnages standardisés dans sept sites de Guyane Française ont révèle, avec quelques exceptions, que les termites xylophages sont relativement peu spécialisés à un site. Au contraire, les espèces du groupe Anoplotermes, ainsi que les termites humivores en général, sont spécialisés à un type de forêt. Cette spécialisation contribue plus que probablement à la diversification écologique, et donc, à une augmentation de la richesse spécifique des termites humivores. (2) En utilisant les ratios d’isotopiques δ13C et δ15N, nous avons aussi trouvé qu’il existe une spécialisation des espèces le long d’un gradient d’humification chez le groupe Anoplotermes, de l’interface entre le bois pourri et le sol au sol pauvre en matière organique. Donc, au moins deux facteurs favorisent la richesse spécifique du groupe Anoplotermes dans le sol, malgré le manque d’évidence pour une séparation spatiale et temporelle entre les espèces. Cette spécialisation spécifique réduit la compétition interspécifique aux espèces se nourrissant de matière organique au même état de décomposition. (3) Ce mécanisme n’est probablement pas restreint aux espèces du groupe Anoplotermes et le ratio isotopique δ15N varie considérablement entre les termites humivores de manière générale. Les termites humivores comptent des espèces avec des régimes alimentaires différents ne partageant pas toujours les mêmes niches écologiques. Cette diversification du régime alimentaire ne c’est pas produit de manière aléatoire durant l’évolution des termites et les espèces proches tendent à se nourrir du même substrat. (4) Au niveau intraspécifique, il semble que la compétition contraigne la dynamique des colonies. En effet, chez A. banksi, nous avons trouvé que les nids matures sont surdispersés. Les nouveaux nids se trouvent principalement à une certaine distance des nids établis, plus particulièrement dans les trous laissés par les nids morts. Si ce patron est le résultat d’une sélection des sites de nidification, ou plutôt d’une exclusion compétitive reste sujet à discussion, mais met néanmoins en évidence la présence de compétition chez les termites humivores du groupe Anoplotermes. (5) Au vu de la richesse spécifique locale du groupe Anoplotermes, le nombre d’espèces décrites reste remarquablement bas. Après inspection du matériel type, seuls 30 espèces du groupe se sont avérés valides en Amérique du Sud, alors que 80% des espèces que nous avons collectées sont nouvelles pour la science. Cette disproportion entre ce qui est connu et la diversité réelle du groupe, met en évidence le besoin de réaliser des études supplémentaires pour améliorer la connaissance de ce groupe peu connu, le groupe Anoplotermes.

Amyloid diseases are a world-wide problem causing great human suffer and large economical costs. Although amyloid deposits, a common denominator in all amyloid disorders, are detrimental to the surrounding tissue, there is a poor correlation between total amyloid burden and clinical symptoms. Soluble oligomers are much more potent to exert a tissue damaging effect.  Alzheimer’s disease (AD) is strongly linked to self-assembly of the amyloid-β (Aβ) peptide. Antibodies selectively targeting cytotoxic Aβ-species are useful both for understanding oligomer formation and for their therapeutic abilities. We hypothesized that the effect of avidity would compensate for a low single site affinity and be enough to selectively target oligomers. To evaluate this hypothesis, we focused on the IgM isotype having ten antigen-binding sites. In accordance with the hypothesis, the IgM isotype effectively bound oligomeric Aβ also in presence of a vast excess of its monomeric counterpart, clearly illustrating the potentiating effect of avidity. As a continuation of this work, we have shown that the avidity effect from a bivalent binding is enough to induce oligomer specificity. This finding facilitates a direct application on the clinically more useful IgG isotype, where the binding properties now can be controlled in detail. The method is general and we have, using this technique, also designed oligomer specific antibodies targeting α-synuclein. Transthyretin (TTR) is an amyloidogenic protein involved in both hereditary and sporadic amyloidosis. The cytotoxicity of TTR is intriguing since studies have shown cytotoxic potential from oligomers, tetramers and even monomers. Elucidation of the molecular properties associated with TTR cytotoxicity is hence of interest. By preventing tetramer dissociation, TTR aggregation and TTR-induced cytotoxicity is abolished. Based on this rationale, a current therapeutic strategy is to stabilize the TTR tetramer with small molecules. The kinetic stability within the spectra of known TTR mutations spans more than three orders of magnitude. However, although the most stable mutants are inert, a poor correlation within the group of cytotoxic variants exists where the cytotoxic effect is not potentiated in proportion to their kinetic stability. Through analysis of a large spectra of TTR variants, our results indicate that TTR induced cytotoxicity requires an intermediate stability of the TTR molecule. The kinetic stability should be low enough to permit tetramer dissociation and the thermodynamic stability high enough to prevent instant aggregation and to allow formation of the cytotoxic fold.

Along the shores of the Northern hemisphere Fucus (Phaeophyceae) species are a prominent presence, providing substrate, shelter, and food for many species. Fucus evanescens, a non-indigenous species (NIS) in Sweden, and F. radicans, a recently described species that so far has only been found inside the species poor Baltic Sea, are the focus of this thesis. Interactions with enemies (e.g. predators, herbivores, parasites) have been shown to play a role in the success of NIS. The low consumption of Fucus evanescens by the generalist gastropod Littorina littorea in Sweden was found to depend on high levels of chemical defense in the introduced population, not the failure of the herbivore to recognize F. evanescens as suitable food. A survey of the relative abundance of F. radicans and F. vesiculosus and the most common associated fauna along the Swedish Bothnian Sea coast showed that F. radicans and F. vesiculosus are equally abundant throughout the range of F. radicans. The most common associated fauna were found to be more abundant on F. radicans compared to F. vesiculosus.  In Sweden, where F. radicans had lower levels of defense chemicals than F. vesiculosus, F. radicans was grazed more than F. vesiculosus in bioassays. This could, together with other factors, influence the range of F. radicans. Fucus radicans and F. vesiculosus are closely related, recently separated, and growing sympatrically, therefore, possible reproductive barriers between F. radicans and F. vesiculosus were studied. In Estonia F. radicans and F. vesiculosus reproduces at different times of the year. No such clear reproductive barrier was found between the two species in Sweden where they reproduce at the same time and fertilization success and germling survival were the same for hybrids as for F. vesiculosus. Since the high clonality of F. radicans means that the gentic diversity in F. radicans populations is low I investigated how genetic diversity translates to phenotypic diversity in nine traits. Phlorotannin levels, recovery after desiccation, and recovery after freezing showed inherited variation, while the other six traits showed no variation related to genetic diversity. Phenotypic variation in populations of F. radicans will be higher in populations with higher genetic diversity and this might be beneficial to the community. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Accepted.</p>

Biological diversity is one out of four dimensions, characterizing the subject of Biology ac-cording to the school curriculum. As a concept, biological diversity had its break through at the UN environmental conference in Rio de Janeiro in 1992, where the convention about bio-logical diversity, named CBD, was signed. According to the convention, almost all the na-tions of the world have engaged themselves to preserve the national diversity of species, in-cluding the diversity of genetics and ecological systems. This thesis focuses the biological diversity from the perspective of school books. The aim is to find out how the biological diversity is presented in biology books for students aged 12-15 years. In 1994, the current Swedish secondary and high school curriculum called LPO-94 was pre-sented. The biology books used in this study were published between 1994 and 2007, all of them exist in many editions and are published by three different publishers. The conclusion of the study is that all the biology books that were examined have reached different levels of the development in the field of biological diversity.

This study investigated the role of an invasive tall cane, Arundo donax L. (Arundo), in the riparian water cycle. Four 100 meter transects were arrayed perpendicular to the lower Rio Grande in southwest Texas. The first objective was to determine the primary water source for Arundo by using naturally occurring stable isotopes. Surface soil, river water, groundwater, precipitation and rhizome samples were collected every month during 2010 and 2011 growing seasons, which coincided with a major flood that saturated soils in the first year followed by extreme drought in the second year. The second objective was to characterize how Arundo water use varied with water availability gradients in the riparian zone. Leaf gas exchange and leaf delta13C were measured along potential moisture gradients. The third objective was to understand the interaction between groundwater and surface water, and whether Arundo water use affected daily groundwater fluctuations. The isotope ratio of rhizome water was consistent with shallow soil moisture uptake and with previous observations of a relatively shallow, fibrous root system. Floodwater from July 2010 persisted in the soil for at least a year despite a severe drought, and became the dominant water source for Arundo during much of the study period. Although the alluvial water table in this floodplain was shallow (< 6 m) and subject to changes in river level, groundwater seemed not to be an important source for Arundo, so long as the soil moisture was sufficient. In this study, Arundo was not found to experience soil moisture limitation, and the spatial variability of Arundo transpiration was not associated with any soil moisture availability gradients. Arundo was found to close its stomata in response to increasing vapor pressure deficit (VPD), causing declining transpiration rate and increasing leaf delta13C composition. Significant exchange between the river and the alluvial groundwater was reflected in the similarity of isotopic compositions and the high correlation between river and groundwater elevations. Cross correlation analysis showed that over 50% of the diurnal groundwater fluctuations were caused by river stage changes. Consistent with the above ecophysiological and stable isotope results, Arundo water use was not found to influence daily groundwater fluctuations.

Integrating mutualism into the study of ecological communities is likely to be critical to understanding community dynamics and to predict the consequences of anthropogenic changes to ecosystems. Invasive species are among the greatest of these threats to global biodiversity. Throughout the Pacific, the invasive ant Anoplolepis gracilipes associates mutualistically with Morinda citrifolia , a native plant with extrafloral nectaries (EFN). I tested the hypothesis that these interactions can mediate invader impacts Anoplolepis gracilipes abundances were positively correlated with the dominance of EFN-bearing plants per site and negatively correlated with the species richness of native ants. Additionally, A. gracilipes displayed a higher magnitude of responses to nectar than other dominant ants. Mutualisms also had significant impacts on the structure of arthropod communities. These effects were strongest when A. gracilipes dominated local ant assemblages. These results suggest that novel mutualisms between invasive and native species can facilitate the impacts of invasions on communities.