Dissertations / Theses on the topic 'Mammal interaction'

Les communautés écologiques sont connues pour être des systèmes complexes composés de multiple espèces entrant en interaction les unes avec les autres. De nombreux modèles théoriques ont été développés pour étudier les communautés. Certains ont souligné l'importance des effets indirects que les espèces pouvaient avoir les unes sur les autres, tels que les chaînes d'interactions et les modifications d'interactions (par modification du trait d'une des espèces en interaction ou de l'environnement où se déroule l'interaction). Bien que la science expérimentale vienne confirmer le rôle fondamental que pourrait avoir ces effets indirects, peu d'études à l'échelle des communautés en milieu naturel ont été conduites, et encore moins chez les grands mammifères. Le Parc National de Hwange, au Zimbabwe, est un écosystème de savane arborée semiaride caractérisé par une quasi-absence d'eau de surface naturelle (point d'eau, rivière) pendant la saison sèche, et ce n'est qu'avec la création de points d'eau artificiels pompés que la richesse spécifique des communautés de grands mammifères et les fortes abondances animales sont maintenues. De plus, cet écosystème a la remarquable particularité à la fois d'abriter l'une des plus fortes densités d'éléphants, et d'être considéré comme l'un des bastions africains pour sa population de lions. Le lion est connu comme étant un chasseur à l'affût, utilisant les éléments de son habitat (fourrés, souches, hautes herbes, etc.) pour se rapprocher au maximum de sa proie et lui bondir dessus par surprise. De plus, cette espèce semble profiter de l'agrégation des herbivores aux points d'eau pendant la saison sèche pour chasser autour de ces points d'eau. L'éléphant d'Afrique quant à lui est capable d'aménager son milieu et est ainsi susceptible de favoriser l'accès à certaines ressources pour les autres espèces, telles que des abris ou au contraire une meilleure visibilité. En revanche, de par sa masse corporelle exceptionnelle et son régime alimentaire généraliste, il est possible qu'il soit un compétiteur clé pour les autres herbivores. Enfin, étant très nombreux dans l'écosystème étudié, nécessitant de grandes quantités d'eau, et devenant de plus en plus agressifs au fil de la saison sèche, les éléphants influencent l'utilisation des points d'eau par les autres herbivores. Cette thèse porte donc sur le rôle que peuvent avoir les éléphants sur les interactions trophiques entre les lions et leurs proies, via des mécanismes d'effets indirects. Différents axes de recherche sont abordés. Le premier porte sur l'effet des éléphants sur la communauté de grands herbivores aux points d'eau, et plus particulièrement comment ils peuvent influencer leur distribution spatiale, et à terme leur vulnérabilité vis-à-vis des prédateurs. Un évitement spatial des éléphants par les autres herbviores en début de saison sèche suggère fortement que les éléphants sont de potentiels compétiteurs. Cependant, à la fin de la saison sèche, le phénomène s'inverse et certaines espèces d'herbivores se rapprochent fortement des éléphants. Deux scénarios portant sur les mécanismes pouvant expliquer ce patron ont été explorés, sans succès : une nécessité croissante d'accéder à de l'eau de meilleure qualité au niveau des pompes des points d'eau, et une augmentation du risque de prédation qui pourrait rendre les éléphants « attractifs » aux yeux des herbivores, les éléphants adultes étant invulnérables à la prédation et capables de les faire fuir par des comportements de harcèlement. Le deuxième axe de recherche porte sur l'effet des éléphants sur la distribution spatiale des herbivores à l'échelles du paysage et de l'habitat, et sur les conséquences possibles que cela peut avoir sur l'écologie spatiale des prédateurs. L'absence de ségrégation entre éléphants et herbivores ne supporte pas l'hypothèse d'un effet de compétition par exploitation, et l'investigation quant à l'effet sur les prédateurs n'a pas été poussée plus avant... [etc]<br>Species can indirectly affect other species and their interactions. The trophic interaction between a predator and its prey can be modified by the presence of a third species either through chain interactions (e.g. successive predation link) either through interaction modification. However, these indirect received few attentions in theorical modelling of food web, and fewer studies tried to explore this phenomenon at the scale of natural complex communities of large mammals. The role of the elephants as modifier of lion’s trophic interaction is explored in the semi-arid woodland savannah ecosystem of Hwange National Park, Zimbabwe. African elephants, as key competitor (male body mass ~ 4000 kg with aggressive behaviour) shape the behaviour of herbivores at waterholes results do not allow to state on the elephant mediation of lion trophic interaction at waterholes. In addition, elephants seem to facilitate the availability of food resources for impalas, possibly by increasing regrowth of shoots by breaking twigs and stem, as these last select habitats used by elephants. However, not effect of facilitation or competition were observed for the other herbivores, which lead to think that elephants do not influence lion trophic interaction in that way. Finally, by altering the physical environment (i.e. engineer species) the elephants affect the visibility and ambush sites for lions in the woody vegetation and ultimately seem to influence the lion kill site selection. This study suggests that indirect effects may act at the community level even if their observation and quantification are difficult in natural communities. Moreover, it supports the observation that it is important to take into account these indirect effects in order to have a thorough understanding and have a better ability to predict the consequences that disruptions may have on the structure and functioning of communities

This study aimed to provide scientific information on the status of marine mammals and threats from directed takes and incidental catches in fisheries in East Malaysia. Recommendations for the conservation of the animals and guidelines for further research are also provided. All available information on sightings, strandings, skeletal remains and threats to the marine mammals in East Malaysia prior to this study were reviewed.  A series of broad and aerial sighting surveys was conducted in the marine and fluvial waters.  The objective was to explore and observe marine mammals at sea, and to describe the present species composition, distribution and density. In conclusion, this study showed that marine mammals in East Malaysian waters are diverse. Dugongs and small citations are facing threats from by-catches in fisheries, declining fisheries resources, habitat loss and degradation, pollution, heavy vessel traffic and rapid urban and industrial development along its coastline.  In Sabah, traditional hunting for meat, illegal trawling in estuarine and riverine waters, and dynamite fishing are particularly detrimental to the species and their habitats.  Without an immediate, committed and concerted effort to educate the public, monitor fisheries, enforce conservation laws and conduct detailed assessment of the dugong and small cetacean populations and their habitats, there may be little hope to reduce or eliminate the threats and to maintain their present numbers in the waters of East Malaysia.

Within the Australian wet tropics bioregion, only 900 000 hectares of once continuous rainforest habitat between Townsville and Cooktown now remains. While on the Atherton Tableland, only 4% of the rainforest that once occurred there remains today with remnant vegetation now forming a matrix of rainforest dispersed within agricultural land (sugarcane, banana, orchard crops, townships and pastoral land). Some biologists have suggested that remnants often support both faunal and floral communities that differ significantly from remaining continuous forest. Australian tropical forests possess a relatively high diversity of native small mammal species particularly rodents, which unlike larger mammalian and avian frugivores elsewhere, have been shown to be resilient to the effects of fragmentation, patch isolation and reduction in patch size. While small mammals often become the dominant mammalian frugivores, in terms of their relative abundance, the relationship that exists between habitat diversity and structure, and the impacts of small mammal foraging within fragmented habitat patches in Australia, is still poorly understood. The relationship between foraging behaviour and demography of two small mammal species, Rattus fuscipes and Melomys cervinipes, and food resources in fragmented rainforest sites, were investigated in the current study. Population densities of both species were strongly related with overall density of seed resources in all rainforest fragments. The distribution of both mammal species however, was found to be independent of the distribution of seed resources. Seed utilisation trials indicated that M.cervinipes and R.fuscipes had less impact on seed resources (extent of seed harvesting) than did other rainforest frugivores. Experimental feeding trials demonstrated that in 85% of fruit species tested, rodent feeding increased seed germination by a factor of 3.5 suggesting that in Australian tropical rainforest remnants, small mammals may play a significant role in enhancing germination of large seeded fruits. This study has emphasised the role of small mammals in tropical rainforest systems in north eastern Australia, in particular, the role that they play within isolated forest fragments where larger frugivorous species may be absent.

Within the Australian wet tropics bioregion, only 900 000 hectares of once continuous rainforest habitat between Townsville and Cooktown now remains. While on the Atherton Tableland, only 4% of the rainforest that once occurred there remains today with remnant vegetation now forming a matrix of rainforest dispersed within agricultural land (sugarcane, banana, orchard crops, townships and pastoral land). Some biologists have suggested that remnants often support both faunal and floral communities that differ significantly from remaining continuous forest. Australian tropical forests possess a relatively high diversity of native small mammal species particularly rodents, which unlike larger mammalian and avian frugivores elsewhere, have been shown to be resilient to the effects of fragmentation, patch isolation and reduction in patch size. While small mammals often become the dominant mammalian frugivores, in terms of their relative abundance, the relationship that exists between habitat diversity and structure, and the impacts of small mammal foraging within fragmented habitat patches in Australia, is still poorly understood. The relationship between foraging behaviour and demography of two small mammal species, Rattus fuscipes and Melomys cervinipes, and food resources in fragmented rainforest sites, were investigated in the current study. Population densities of both species were strongly related with overall density of seed resources in all rainforest fragments. The distribution of both mammal species however, was found to be independent of the distribution of seed resources. Seed utilisation trials indicated that M.cervinipes and R.fuscipes had less impact on seed resources (extent of seed harvesting) than did other rainforest frugivores. Experimental feeding trials demonstrated that in 85% of fruit species tested, rodent feeding increased seed germination by a factor of 3.5 suggesting that in Australian tropical rainforest remnants, small mammals may play a significant role in enhancing germination of large seeded fruits. This study has emphasised the role of small mammals in tropical rainforest systems in north eastern Australia, in particular, the role that they play within isolated forest fragments where larger frugivorous species may be absent.

The rules and mechanical forces governing cell motility and interactions with the extracellular matrix of a tissue are often critical for understanding the mechanisms by which breast cancer is able to spread through the breast tissue and eventually metastasize. Ex vivo experimentation has demonstrated the the formation of long collagen fibers through collagen gels between the cancerous mammary acini responsible for milk production, providing a fiber scaffolding along which cancer cells can disorganize. We present a minimal mechanical model that serves as a potential explanation for the formation of these collagen fibers and the resultant motion. Our working hypothesis is that cancerous cells induce this fiber formation by pulling on the gel and taking advantage of the specific mechanical properties of collagen. To model this system, we present a hybrid method where we employ a new Eulerian, fixed grid simulation known as the Reference Map Method to model the collagen as a nonlinear viscoelastic material coupled with a multi-agent model to describe individual cancer cells. We find that these phenomena can be explained two simple ideas: cells pull collagen radially inwards and move towards the tension gradient of the collagen gel, while being exposed to standard adhesive and collision forces. From a computational perspective, we hope that our work can serve as a generalizable framework for future theoretical studies of the mechanical interactions between a large number of cells and a dynamic environment.

The deployment of camera traps, which automatically take pictures of wild animals moving in front of them, is now routinely used to survey terrestrial mammal communities worldwide. The resulting photographic data are used to answer questions relating to the richness and structure of mammal communities, the density of their component species, and how the latter might interact. This thesis fills key methodological gaps in how these questions are addressed. My first data chapter assesses how the exact placement of camera traps on natural game trails influences the characterisation of community richness, composition and structure in an east African savannah landscape. I find that a trail-based placement strategy leads to more species being detected more rapidly relative to a random one, and increases capture rates for carnivore species in particular. In contrast, I reveal in Chapter 3 how a non-random camera trap placement strategy can bias estimates of absolute density for an unmarked large carnivore, the lion Panthera leo, obtained using an ideal gas model approach. Chapter 4 considers spatiotemporal patterns in camera trap data, and to what extent they can be used to infer on the kleptoparasitic and predatory tendencies of spotted hyenas and lions, respectively, in Tanzania's Ruaha landscape. I find patterns to be generally uninformative, and so, in Chapter 5, turn to another method of collecting spatiotemporal data, Global Positioning Satellite telemetry, to make inferences on the spatial response of elk to wolves in Yellowstone National park. I find no evidence for a significant spatial avoidance of wolves by elk, suggesting that species interactions may not always lead to measurable spatial patterns. Nevertheless, in my final chapter, I use an individual-based modelling framework to simulate different types of prey responses to predator movement in the absence of confounding factors, and find that a huge amount of camera trapping effort would be required to distinguish between them. This thesis highlights how camera trap placement can affect the description of mammal communities and the estimation of species density. It also shows that we cannot rely solely on spatiotemporal patterns derived from camera traps to make inferences on complex interactive processes.

Vitamin B12, or cobalamin, is a water soluble vitamin required as cofactor for two mammalian enzymatic processes: homocysteine remethylation to methionine in the cytoplasm using methionine synthase (MS), and fatty acid/amino acid metabolism in the mitochondrion using methylmalonyl-CoA mutase (MCM). Whereas the molecular nature of intracellular cobalamin metabolism in mammals remains poorly understood, the proteins MMACHC, MMADHC, LMBD1 and ABCD4 are implicated in its early uptake and processing. Due to the inherent challenges associated with the cellular utilization of cobalamin, we propose that these proteins mediate its early intracellular channeling; the objective of this thesis was to characterize the protein-protein interactions that coordinate this process.To gain insight into the function of MMADHC, recombinant isoforms were purified and low-resolution structural features were determined. MMADHC is monomeric and, in solution, adopts an extended conformation, with regions of disorder identified at the N-terminal domain. Panning combinatorial phage libraries against recombinant MMADHC allowed the mapping of putative sites of interaction on MMACHC. Kinetic analyses using surface plasmon resonance (SPR) confirmed a sub-micromolar affinity for the MMACHC–MMADHC interaction. Based on these studies, we propose that the function of MMADHC is exerted through its structured C-terminal domain via interactions with MMACHC in the cytoplasm.Clinical phenotypes and subcellular location of MS and MCM dictate that MMACHC functions in the cytoplasm while MMADHC functions at a branch point in the pathway in both the cytoplasm and the mitochondrion. To demonstrate that the MMACHC–MMADHC interaction is physiologically plausible, we used immunofluorescence and subcellular fractionation to confirm that MMACHC is cytoplasmic while MMADHC is dual-localized to the cytoplasm and mitochondria. Protein interaction analyses were extended by describing the recombinant production of the lysosomal membrane proteins LMBD1 and ABCD4. Detergent-solubilized LMBD1 and ABCD4 each formed homodimers in solution. SPR provided direct in vitro binding data for an LMBD1–ABCD4 interaction with low nanomolar affinity. Consistent with our phage display predictions, MMACHC interacted with LMBD1 and ABCD4 with high affinity.Our results support a model whereby membrane-bound LMBD1 and ABCD4 regulate the vectorial delivery of lysosomal cobalamin to cytoplasmic MMACHC, preventing cofactor dilution to the cytoplasmic milieu and protecting against inactivating side reactions. Subsequent formation of a cytoplasmic MMACHC–MMADHC complex then processes and partitions this cofactor to the downstream enzymes MCM and MS. These studies identify and characterize multiprotein complexes, advancing our basic understanding of early intracellular cobalamin metabolism.<br>La vitamine B12, ou bien la cobalamine, est une vitamine soluble requise pour deux processus enzymatiques distincts chez les mammifères; la production de l'acide aminée méthionine par la méthionine synthase (MS), et le métabolisme d'acides gras et d'acides aminées par la méthylmalonyl-CoA mutase (MCM). Malgré le fait que les procédées métaboliques intracellulaires de la cobalamine restes peu bien caractérisés, les protéines dont MMACHC, MMADHC, LMBD1, et ABCD4 jouent un rôle dans l'acquisition et le traitement de ce cofacteur. Vu les difficultés intrinsèques de l'utilisation cellulaire de la cobalamine, nous proposons que ces protéines assurent l'efficacité de son canalisation. Cette thèse avait pour objectif de caractériser les interactions protéine-protéine impliquées dans ce processus.Pour pouvoir caractériser la fonction de MMADHC, des isoformes protéiques ont été purifiées et leurs traits structurales ont étés déterminés à basse résolution. MMADHC se trouve à être monomérique et adopte une conformation étendue en solution, avec des régions non structurées dans la terminaison aminée de la protéine. Ensuite, des librairies combinatoires de phages ont été utilisées comme substrats pour tracer des sites d'interactions potentiels avec MMADHC. Les analyses kinésiques des interactions MMACHC–MMADHC ont été faites à l'aide de la résonance plasmonique de surface (SPR) et ont confirmées une intéraction d'affinité sub-micromolaire. Avec ces résultats, nous proposons que la fonction de MMADHC se fasse par sa terminaison acidique en interagissant avec MMACHC dans le cytoplasme.Les phénotypes cliniques et la localisation subcellulaire de MS et de MCM envisagent que MMACHC joue un rôle dans le cytoplasme et que MMADHC se trouve à être impliquée dans le processus au niveau de la mitochondrie et du milieu cytoplasmique. Pour démontrer que l'interaction MMACHC–MMADHC est physiologique, nous avons utilisé l'immunofluorescence et la fractionnement subcellulaire pour confirmer que MMACHC est cytoplasmique et que MMADHC se retrouvent au cytoplasme et au mitochondrie.Des analyses protéiques ont également engendré LMBD1 et ABCD4. Solubilisés à l'aide de détergent, ces deux protéines prennent la conformation d'homodimères en solution. Une interaction d'affinité nanomolaire entre LMBD1 et ABCD4 a été confirmée en SPR. En lien avec nos analyses de phages, MMACHC interagit avec haute affinité avec LMBD1 et ABCD4.Nos résultats supportent un modèle dans lequel LMBD1 et ABCD4, tous deux liés dans la membrane, régularisent l'octroi de la cobalamine lysosomale à MMACHC en prévenant la dilution de ce cofacteur dans le milieu cytoplasmique et en protégeant contre des réactions inactivant. La dissociation et le recrutement de la MMADHC cytoplasmique à MMACHC facilitent le transfert de la cobalamine vers les réactions enzymatiques catalysées par MCM et MS. L'identification et la caractérisation de ces complexes multiprotéiques font en sorte d'avancer nos connaissances générales sur le métabolisme de la cobalamine.

Female mammals play a central role in determination of social structure and are thus central to understanding the overall fission-fusion grouping pattern characteristic of many delphinid societies. Focusing specifically on female-female relatedness and association patterns, I have analysed more than 17 years of group composition, behavioural data, and genetic information to investigate complex interactions between behavioural ecology and relatedness and to also examine the common social evolutionary theory, that variation in mammalian social systems is typically attributed to five main factors: inclusive fitness, predation pressure, sexual conflict and male harassment, inbreeding avoidance, and resource competition. Overall, I found that female bottlenose dolphin association patterns depend upon the interplay between matrilineal kinship, biparental relatedness and home range overlap, and that female bottlenose dolphins seem to adapt their social strategies to seasonal variation in levels of predation and male harassment. The presence of both high sexual conflict and bisexual philopatry lead me to investigate the extent of inbreeding avoidance. I found that more than 14% of the calves were most likely the product of mating between close relatives, and identified female fitness costs to inbreeding. We were able to show that the effect of inbreeding on females??? fitness occurs via two independent mechanisms: being inbred and having at least one inbred calf. Inbred calves are on average weaned later than non-inbred calves, and a female???s first calf has a higher probability to be an inbred than subsequent calves. Last, I examined whether sociality provides inclusive fitness to female bottlenose dolphins through an investigation of both the additive genetic and social variance components of female calving success using a pedigree-free animal model. I found that variance in calving success of female bottlenose dolphins is best explained by complex genetic and social interactions. Females with high calving success showed both high genetic and social merit; they not only have good genes but also prefer to associate with others of high fitness. This study reveals that both social and heritable genetic variance contribute to fitness trait variance in the wild.

L'acide aminé sélénocystéine est codé par UGA qui agit généralement comme un codon stop. Une machinerie spécialisée est utilisée pour incorporer cet acide aminé dans les sélénoprotéines qui implique une structure en tige-boucle, appelée SECIS, et des protéines. L'une d’elles est SBP2, SECIS Binding Protein 2. Pour mieux comprendre ce mécanisme et identifier de nouveaux partenaires de l'élément SECIS, deux stratégies ont été développées. 1/ identification des contacts de l’élément SECIS avec le ribosome par des pontages covalents. Dans ce but, j’ai construit des ARN messagers modèles, l’élément SECIS contenant des agents pontants. Après action des UV, il s’avère que SBP2 est liée au SECIS dans les complexes 48S et 80S de pré-translocation. Lorsque la formation de la liaison peptidique est bloquée par l’anisomycine, l’élément SECIS n’est plus lié à SBP2 mais à des protéines ribosomiques, SBP2 étant présente dans le complexe. L'interprétation est la suivante. Pendant la transpeptidation, SBP2 est associée au ribosome mais ensuite SBP2 le quitte et se lie au SECIS à l'étape de pré-translocation. 2/ Le site de liaison de SBP2 sur la sous-unité 60S n’avait pas encore été localisé. Les complexes SBP2-40S, 60S-SBP2 et 80S-SBP2 ont été soumis aux diépoxybutane ou 2-iminothiolane. Nous avons montré que SBP2 se lie à la sous-unité 60S uniquement et que l'ARNr 28S contribue davantage au site de liaison que les protéines ribosomiques. Pour identifier cette région de l’ARNr 28S, les radicaux hydroxyles ont été employés et nous avons montré que SBP2 réside sur le côté solvant de la sous-unité 60S, à proximité du site A<br>The amino acid selenocysteine is encoded by a UGA triplet which acts generally as a stop codon. A specialized machinery is used to incorporate this amino acid into selenoproteins, involving a specific stem-loop, termed SelenoCysteine Insertion Sequence (SECIS), and some protein factors. One of those is the SECIS Binding Protein 2 (SBP2), which is necessary for ribosome recognition of the UGA as the Sec codon. Using synthetic selenocysteine mRNAs and translational inhibitors, several steps of mRNA translation were analyzed. The data obtained allowed us to propose the following mechanism for selenocysteine insertion : during the transpeptidation step of elongation, SBP2 is bound to the ribosome; however, after transpeptidation, SBP2 leaves the ribosome and binds the SECIS in the pre-translocation step. We showed earlier that SBP2 binds specifically to the purified human 60S but not to the 40S ribosome subunits but the actual location was unknown. The SBP2•40S, SBP2•60S and SBP2•80S complexes were thus studied using crosslinking reagents. SBP2 did not crosslink to the 40S subunit in either the 40S•SBP2 or 80S•SBP2 complexes, correlating with the binding data. However, SBP2 crosslinks to the 60S subunit in either the free state or in the 80S ribosome. I next showed that the 28S rRNA contributes more to the crosslink than ribosomal proteins. This led us to use hydroxyl radical footprinting to study the molecular environment of SBP2 on the ribosome. According to the probing data, the binding of SBP2 to the human 60S subunit protects 2 helices in expansion segment 7 of the 28S rRNA. I proposed that the SBP2 binding site is located in the vicinity of the L7/L12 stalk

Predation by exotic predators (cats Felis catus and foxes Vulpes vulpes) is believed to be one of the factors that has contributed to the decline of medium-sized mammals in arid Australia. Other factors include habitat degradation by introduced herbivores (rabbits Oryctolagus cuniculus and grazing stock) and altered fire regimes after Aboriginal people moved into permanent settlements. In general, the impact of exotic predators on arid zone mammals is believed to be significant only when predator numbers have been elevated by increased food availability from exotic prey species (rabbits, house-mice Mus domesticus, cattle carcasses) or when native prey populations have already been dramatically reduced by competition from introduced herbivores. In much of the spinifex grasslands of the central Australian deserts, pastoralism never occurred, rabbit colonisation was extremely patchy and in some areas, traditional burning was still being practised when the extinctions commenced. None of the current models of mammalian extinctions adequately explain the declines in this environment. In this study I examined predator-prey interactions in two areas of the Tanami Desert to investigate whether predation by exotic predators may be a primary agent of extinction in its own right, capable of causing mass declines even in the absence of other human-induced perturbations. If this were the case then the following would be expected: (i) cats and foxes would eat medium-sized mammals when they are available, but be able to survive on alternative prey when mammals are scarce; (ii) populations of cats and foxes would be buffered against the declines of mammals during droughts, or would be able to recover more quickly than medium-sized mammals after droughts; (iii) medium-sized mammals would be more vulnerable to predation by cats and foxes than by dingoes Canis lupus dingo and other native predators, and (iv) there would be a correlation between the timings of the extinctions and the colonisation (or sudden increase) of cats and foxes. These predictions were investigated by monitoring the diets and relative abundance of cats, foxes and dingoes in relation to fluctuating prey availability in two areas of the Tanami Desert at latitudes separated by approximately 400 km. Mean annual rainfall is higher and more reliable in the northern study area which was situated in the centre of bilby Macrotis lagotis distribution within the Northern Territory, whereas the southern study area was located on the southern edge of the bilby�s range. Within each study area, monitoring occurred at three sites, approximately 20 km apart. Each site contained a sub-plot in each of two habitat types. Field work was conducted between September 1995 and December 1997. When the study began, the southern study area was experiencing drought conditions, however both study areas received significant rainfall in early 1997. The population dynamics of a variety of potential prey groups were monitored to examine their resilience during droughts, patterns of recolonisation after rainfall, and use of two habitat types: the ubiquitous sandplain, and the moister, nutrient enriched palaeodrainage habitat which is believed to have provided a refuge for medium-sized mammals during droughts. Native mammals were uncommon throughout the study period. Bilbies and macropods were significantly more abundant in the northern study area, and tended to occur more frequently in palaeodrainage habitat than sandplain. However, the palaeodrainage habitat did not appear to provide adequate refuge for the medium and large mammals during drought conditions in the southern study area, as they disappeared from the study sites altogether. Small mammals were significantly more abundant in the southern study area but densities remained low (less than 2% trap success) throughout the study, and showed little response to improved seasonal conditions. In contrast, the abundance and species richness of birds showed a marked increase following rainfall in the southern study area. Flocks of nomadic birds arrived within several months of drought-breaking rains, increasing the relative abundance of birds from 9.3 per km of transect in December 1996 to 49/km in July 1997. Reptiles were the most resilient prey group during the drought conditions. Both varanids and smaller reptiles were equally abundant in the wet and dry years and showed no difference in abundance between study areas. However, reptiles showed marked temperature-related patterns in activity, with many species becoming inactive in the winter months. A total of 142 cat scats, 126 fox scats and 75 dingo scats were analysed to investigate predator diets in the two study areas. Unlike cat, fox and dingo diets elsewhere in Australia (and the world), mammalian prey did not dominate. Reptile was the prey category that was most frequently consumed by cats and foxes in �summer� (October-April) and by dingoes throughout the year, and was identified as a �seasonal staple� prey type for all three predators in the Tanami Desert. When biomass of prey was taken into account, the varanids (predominantly the sand goanna Varanus gouldii) were the most important prey sustaining predators in the two study areas. Birds were an important part of the diets of cats and foxes in winter when reptiles were less active. Small mammals were consumed by cats and foxes throughout the study, in proportion to their field abundances. Invertebrates were a major component of the diets of foxes, representing 31% of prey items consumed. There was considerable overlap in the diets of the three predator species, but dingoes ate more medium (100-999 g) and large (greater than 1000 g) prey than cats and foxes did. The scarcity of medium-sized mammals in the study areas provided little opportunity to find evidence of predation events on such prey. However, bilby remains were found in two cat scats and one dingo scat in the northern study area, mulgara Dasycercus cristicauda remains occurred in several cat and fox scats from the southern study area, and there were fourteen occurrences of marsupial mole Notoryctes typhlops in predator scats during the study, primarily in fox scats. Elsewhere in Australia, there is ample evidence that cats and foxes regularly consume medium-sized mammalian prey (e.g. rabbits and ringtail possums Pseudocheirus peregrinus) when it is available. Overall cats were the most abundant eutherian predators in the two study areas, and they were significantly more abundant in the northern study area than the southern study area. Surveys revealed that cats can persist into droughts by feeding on reptilian prey. When the study commenced, cats occurred on five of the six sub-plots in the southern study area, despite six consecutive years of below-average rainfall. However, by the end of the first year, they could only be detected on one sub-plot. Recolonisation of the sites rapidly occurred after significant rainfall (260 mm in 2 months), when nomadic birds colonised the sites and provided a plentiful food source. Foxes also declined to very low densities during drought in the southern study area, but they had recolonised all sites by the winter of 1997. This coincided with the increase in abundance of birds, which became their most frequently consumed prey item. Overall, foxes were equally abundant in the two study areas, but statistical analyses revealed a significant interaction between latitude and habitat because in the southern study area foxes tended to utilise the palaeodrainage habitat more than the sandplain, whereas in the northern study area the majority of fox sign was detected in the sandplain habitat. This may have been due to the abundance of dingoes in the palaeodrainage habitat in the northern study area. Dingoes were significantly more abundant in the northern study area than the southern, where they were usually only present at one of the three sites. The northern study area had higher densities of macropods (supplementary prey for dingoes) and more reliable access to drinking water, which persisted in the palaeodrainage channels for up to 6 months after significant rain events. Dingo numbers were relatively stable throughout the study and did not increase in response to improved seasonal conditions in the southern study area in 1997. This study revealed that the distribution of foxes extends further north into the Tanami Desert than has previously been reported, and is not necessarily tied to the distribution of rabbits in the Northern Territory. Furthermore, discussion with Aboriginal people who lived a traditional lifestyle in the area until the 1940s, revealed that foxes were already present in the northern Tanami desert at that time, before the disappearance of many medium-sized mammal species. The patterns of medium-sized mammalian extinctions in the northern and western deserts between 1940 and 1960 is thus consistent with the colonisation of the fox. Although cats had been present in central Australia for at least 50 years before the mammalian declines occurred, this does not discount them from contributing to the extinction process. It is postulated that during the early decades of their colonisation of the arid interior, cat populations may have been maintained at low levels by predation from dingoes and also Aboriginal people (for whom cats were a favoured food). But between 1920 and 1960 the western deserts were depopulated of Aboriginal people, and human hunting of cats diminished. This coincided with the introduction of the dingo bounty scheme, which encouraged many Aboriginal people to continue making regular excursions into the deserts to collect dingo scalps. In this study, cat remains occurred in 9% of dingo scats, suggesting that dingoes may be an important predator of cats. Thus, there may have been an increase in the cat population between 1930 and 1960, producing a more significant impact on native mammal populations than had previously occurred. Information collected during this study was used to construct a new model of mammalian extinctions in the spinifex grasslands of central Australia that promotes predation by cats and foxes as the primary agent of extinction. The model proposes that cats and foxes will eat medium-sized mammals when they are available, but are capable of subsisting on naturally occurring alternative prey when mammals are scarce. Thus, cats and foxes can persist into drought periods by feeding on reptilian prey, which remains an abundant resource regardless of rainfall (at least during the warmer months). Predator populations eventually decline after a series of dry winters. When the drought breaks, the rapid response of nomadic birds provides a readily available food source for cats and foxes as they recolonise areas and commence breeding. Predation by cats and foxes thereby has the potential to exacerbate the declines of native prey populations during droughts and delay their recovery when seasonal conditions improve. In this way, introduced predators are capable of causing local extinctions of medium-sized mammals when populations contract during drought periods, even in the absence of introduced herbivores and altered fire regimes. Although dingoes also prey upon medium-sized mammals, dingoes did not cause extinctions of medium-sized mammals in the spinifex grasslands because (i) they are more reliant on drinking water than foxes and cats, thus waterless areas would have provided some degree of predation refugia, and (ii) their social structure and territoriality prevent high densities accumulating, even when resources are abundant. If further extinctions of medium-sized mammals (such as the bilby) are to be prevented, it may be necessary for wildlife managers to establish a series of predation refugia where fox and cat populations can be controlled without extinguishing local dingo populations. This could be achieved with a combination of predator-proof enclosures, zones in which foxes are killed through poison baiting and areas where Aboriginal people are employed to utilise traditional hunting methods to control introduced predators.

Le Cd est un métal lourd toxique très répandu. L'homme peut être exposé à ce contaminant environnemental par la fumée, la nourriture et l'eau. Le déoxynivalénol (DON) est l'une des mycotoxines les plus répandues dans les céréales. Si de nombreuses études ont étudié la toxicité du DON et du Cd individuellement, leur toxicité combinée est très peu connue. Cependant, les consommateurs peuvent être exposés à un mélange DON et Cd. Dans la présente étude, nous nous sommes concentrés sur les effets du DON et du Cd, seuls ou en combinaison, en utilisant une approche in vitro. Différentes lignées cellulaires humaines provenant du rein (HEK-293), de l'intestin (Caco-2), du sang (HL-60) et du foie (HepG2) ont été exposées à une gamme de doses de DON et Cd seuls et en combinaison. La toxicité induite a été évaluée avec le test CellTiter-Glo(r) Luminescent Assay, basé sur la mesure de la teneur en ATP, proportionnelle au nombre de cellules viables. Les interactions entre DON et Cd ont été analysées à l'aide de la méthode de l'indice de combinaison /isobologramme basée sur de l'équation à effet médian de la loi d'action de masse de Chou et Talalay (2006). Les cellules HEK-293 ont été exposées à des doses croissantes de DON, Cd et leur combinaison à différents ratios (DON / Cd de 2/1, 1/1, 1/2 et 1/8). Indépendamment du ratio, le type d'interaction observé dans les cellules HEK-293 allait de l'antagonisme modéré à presque additif. Dans les cellules Caco-2, les interactions variait de la légère synergie à l'antagonisme, quel que soit le ratio. Au ratio 1/1, dans les cellules HL-60 et HepG2, les interactions variaient de la synergie à l'antagonisme en fonction du niveau de cytotoxicité. Dans le milieu additionné de 1% de sérum de veau fœtal (FCS), la nature des interactions entre le DON et Cd sur les cellules HEK-293 et Caco-2 n'a pas montré de différence significative par rapport au milieu avec 10% de FCS. Les effets du DON et du Cd sur la fonction barrière intestinale et l'expression des gènes ont été évalués. Sur la perméabilité des monocouches de Caco-2, le DON et le mélange DON / Cd ont montré un effet dose-dépendant tandis qu'aucun effet n'a été observé pour le Cd. Le DON a induit une altération significative des cytokines inflammatoires alors que le Cd a montré une surexpression des gènes de la métallothionéine. Dans le milieu supplémenté avec 1% de FCS, nos résultats préliminaires ont montré des effets du Cd sur la fonction de barrière intestinale. Les effets combinés du DON et du Cd sur l'intégrité de barrière des cellules Caco-2 différentiées variait d'un antagonisme modéré à presque additif. En conclusion, notre étude indique que l'exposition combinée au DON et au Cd est spécifique à l'organe cible et au stade de développement de la cellule. De plus, les interactions entre le DON et le Cd devront être étudiées dans des expériences ex vivo et in vivo pour confirmer ces résultats<br>Cadmium (Cd) is a common and widespread toxic heavy metal. Human can be exposed to this environmental contaminant through smoke, food and water. Deoxynivalenol (DON) is one of the most prevalent mycotoxins in cereals. If numerous studies investigated the toxicity of DON and Cd individually, very little is known about their combined toxicity. However, consumers can be exposed to a cocktail DON and Cd. In the present study, we focused on the effects of DON and Cd, alone or in the mixture using in vitro approach. Different human cell lines from kidney (HEK-293), intestine (Caco-2), blood (HL-60) and liver (HepG2) were exposed to a range of doses of DON and Cd alone and in combination. The induced toxicity was evaluated with CellTiter-Glo(r) Luminescent Assay, based on the measure of ATP content, proportional to the number of viable cells. Interactions between DON and Cd were analyzed with isobologram-combination index method derived from the Median-Effect Equation of the Mass Action Law of Chou and Talalay (1984). HEK-293 cells were exposed to increasing doses of DON, Cd and their combinations at different ratios (DON/Cd of 2/1; 1/1; 1/2 and 1/8). Regardless of the ratio, the type of interaction observed in HEK-293 cells ranged from moderate antagonism to nearly additive. In Caco-2 cells, the interactions ranged from slight synergy to antagonism whatever the ratio. At ratio 1/1, in HL-60 and HepG2 cells, interactions ranged from synergy to antagonism depending on the cytotoxicity level. In the medium supplemented with 1% Fetal Calf Serum (FCS), the interaction of DON and Cd on HEK-293 and Caco-2 cells did not show a significant difference compared to medium with 10% FCS. Then, the effects of DON and Cd on the barrier function and gene expression were evaluated. On Caco-2 monolayers permeability, DON and DON/Cd mixture showed a dose- dependent effect while no effect was observed with Cd. DON-induced a significant alteration of inflammatory cytokines whereas Cd showed overexpression of metallothionein genes. In medium supplemented with 1% FCS, our preliminary results showed effects of Cd on intestinal barrier function. The combined effects of DON and Cd on Caco-2 cells barrier function ranged from moderate antagonism to nearly additive. In conclusion, our study indicates that the combined exposure to DON and Cd is specific to the target organ and development stage of the cells. Moreover, the interactions between DON and Cd will have to be investigated in ex vivo and in vivo experiments to confirm these results

L’esperienza di aspettare e di essere genitore di due gemelli è innegabilmente diversa rispetto alla gravidanza alla genitorialità nel caso di un singolo bambino. La nascita gemellare è associata a conseguenze mediche, sanitarie, socio-emotive, psicologiche e dello sviluppo. Lo scopo di questo lavoro è stato quello di aggiungere conoscenze rispetto agli aspetti unici legati alla gravidanza gemellare e alla genitorialità. Ho esaminato il modo in cui le future mamme vivono la loro gravidanza e come le madri sperimentano l’essere genitori di due gemelli e come queste interagiscono con i loro bambini nel periodo post-partum. Per studiare meglio l'esperienza di aspettare e di essere madre di due gemelli, i risultati sono stati confrontati con la letteratura esistente e sono stati utilizzati diversi progetti di ricerca. È stata valutata la validità e le proprietà psicometriche della versione italiana del Baby Care Questionnaire; è stato valutato se l'esperienza unica di un gemello in attesa potesse influenzare negativamente l'attaccamento prenatale; è stato esplorato l'impatto della nascita gemellare sull'interazione madre-figlio nel primo periodo post-partum. Questa tesi ha stabilito che le madri di gemelli hanno esigenze particolari e affrontano sfide uniche. Le madri di gemelli sembrano essere meno adattate dal punto di vista psicologico alla loro gravidanza in termini di basso livello di attaccamento prenatale. Anche la costruzione di una relazione stretta e positiva potrebbe essere più difficile nel caso dei gemelli.<br>The experience of expecting and parenting twins is undeniably different from that of a singleton pregnancy and parenthood. Twin births are associated with medical, health care, socio-emotional, psychological and developmental consequences. The aim of this work was to add knowledge concerning the unique aspects of expecting and parenting twins. I examined the way the mothers-to-be live their pregnancy as well as how mothers experience parenting twins and interact with their babies in the post-partum period. To better investigate the unique experience of expecting and parenting twins, results were compared with the existing literature and different research design were used. It was evaluated the validity and the psychometric properties of the Italian version of the Baby Care Questionnaire; it was investigated if the unique experience of expecting twin may adversely affect prenatal attachment; it was explored the impact of twin birth on mother-child interaction in the early post-partum period. This thesis established that mothers of twins have unique needs and face unique challenges. Mothers of twins seems to be less psychological adjusted to their pregnancy in terms of lower level of prenatal attachment. Also the building of a close and positive relationship could be more difficult in the case of twins.

L’esperienza di aspettare e di essere genitore di due gemelli è innegabilmente diversa rispetto alla gravidanza alla genitorialità nel caso di un singolo bambino. La nascita gemellare è associata a conseguenze mediche, sanitarie, socio-emotive, psicologiche e dello sviluppo. Lo scopo di questo lavoro è stato quello di aggiungere conoscenze rispetto agli aspetti unici legati alla gravidanza gemellare e alla genitorialità. Ho esaminato il modo in cui le future mamme vivono la loro gravidanza e come le madri sperimentano l’essere genitori di due gemelli e come queste interagiscono con i loro bambini nel periodo post-partum. Per studiare meglio l'esperienza di aspettare e di essere madre di due gemelli, i risultati sono stati confrontati con la letteratura esistente e sono stati utilizzati diversi progetti di ricerca. È stata valutata la validità e le proprietà psicometriche della versione italiana del Baby Care Questionnaire; è stato valutato se l'esperienza unica di un gemello in attesa potesse influenzare negativamente l'attaccamento prenatale; è stato esplorato l'impatto della nascita gemellare sull'interazione madre-figlio nel primo periodo post-partum. Questa tesi ha stabilito che le madri di gemelli hanno esigenze particolari e affrontano sfide uniche. Le madri di gemelli sembrano essere meno adattate dal punto di vista psicologico alla loro gravidanza in termini di basso livello di attaccamento prenatale. Anche la costruzione di una relazione stretta e positiva potrebbe essere più difficile nel caso dei gemelli.<br>The experience of expecting and parenting twins is undeniably different from that of a singleton pregnancy and parenthood. Twin births are associated with medical, health care, socio-emotional, psychological and developmental consequences. The aim of this work was to add knowledge concerning the unique aspects of expecting and parenting twins. I examined the way the mothers-to-be live their pregnancy as well as how mothers experience parenting twins and interact with their babies in the post-partum period. To better investigate the unique experience of expecting and parenting twins, results were compared with the existing literature and different research design were used. It was evaluated the validity and the psychometric properties of the Italian version of the Baby Care Questionnaire; it was investigated if the unique experience of expecting twin may adversely affect prenatal attachment; it was explored the impact of twin birth on mother-child interaction in the early post-partum period. This thesis established that mothers of twins have unique needs and face unique challenges. Mothers of twins seems to be less psychological adjusted to their pregnancy in terms of lower level of prenatal attachment. Also the building of a close and positive relationship could be more difficult in the case of twins.

The landscapes of the Great Basin and Mojave Deserts are changing due to plant invasion. Highly flammable invasive grasses increase the size and frequency of fire causing a cascade of effects through the plant and animal communities. One of the most influential animal groups in desert systems is small mammals. We sought to learn how small mammals are impacted by fire and how their influence on the plant community differs between burned and unburned habitat. Small mammals did not have higher rates of mortality as a direct result of a controlled burn. In the Great Basin, there were short-term reductions in abundance, richness, and diversity of the small mammal community in burned plots. In the Mojave, species richness and diversity increased in burned plots shortly after fire and no abundance differences were detected. These results correspond with our prediction based on the dominant small mammal species at each site. Small mammals are primarily granivores; however, they also have strong impacts on the plant community via folivory. We tested for small mammal impacts on seedling survival in burned and unburned habitat. Small mammal access, burned vs. unburned habitat, and plant species were all important determinants of survival. Small mammals greatly reduced survival at both sites in burned and unburned habitat and often had a stronger impact in unburned than burned plots. Accounting for small mammal folivory may be a crucial step in successful post-fire rehabilitation. Finally, we used seed trays to test how small mammals influence the persistence of seed on the landscape. Small mammals reduced persistence of an invasive and native plant species in the Great Basin in 2012, yet a year later when small mammal abundance was reduced, no small mammal effect was observed. In the Mojave, persistence was reduced for the majority of species both years of the study. Small mammals did not appear to avoid seed of invasive plant species as we had predicted and may be important consumers reducing the reproductive potential of these invaders. If small mammals do prefer non-native seedlings over natives and are also consuming non-native seed, they may be greatly reducing the presence of non-natives both on the unburned landscape as well as after fire. Non-native consumption by small mammals could aid in the biotic resistance of these desert ecosystems. This research further enforces the important role that small mammals play as consumers, dispersers, and regulators of the plant community.

Driving into Yellowstone National Park for the first time is a moving experience. Gazing over the sweeping landscapes, seeing a geyser erupt 80 feet into the air, and having your first ‘wildlife encounter’, whether that be a 2 ton bull bison aggressively wallowing on his dirt mound, snorting and kicking up dust, or watching a pack of 6 wolves move through a valley off in the distance, pausing to howl in search of their companions. Yellowstone staff wishes to manage our park in a way that preserves these remarkable experiences. In order to effectively manage this dynamic ecosystem, it is critical to thoroughly understand how different animal and plant species interact with each other and their environment. Wolves were reintroduced to Yellowstone in 1995-1997 and park researchers and managers are still trying to understand how their presence impacts the ecosystem. In Yellowstone, wolves primarily prey on elk; however, predation on bison has started to increase in recent years. We still know little about how wolves hunt bison and what impacts wolves have had on how bison use their environment. The objective of this study was to better understand the behavioral and ecological interactions of wolves and bison, the most dangerous prey for wolves in North America. Since reintroduction, researchers have collected data on how wolves hunt both elk and bison. I used these data to understand 1) the conditions that allow wolves to capture their most dangerous prey, bison, 2) whether wolves have started preying on bison more often as the bison population increased, and 3) whether wolf reintroduction has limited bison use of Yellowstone’s most extreme high-elevation winter range. Finally, I collaborated with ecologists in Scandinavia to determine how wolf predation was affected by a competitor, the brown bear. My study adds to the current body of work addressing the effects of wolf reintroduction in Yellowstone. This research is unique because it focuses on wolf bison interactions, about which little is known in this system. This research also sheds light on the behavioral relationships at play in a special type of predator-prey interaction: predators that hunt dangerous prey

Human-wildlife conflicts (HWC) emerge as complex conservation challenges impairing human livelihood and wildlife populations. Research on HWC, however, has traditionally approached these components apart and focused on single/ similar species, hampering a broader understanding of the connections between ecological drivers and human dimensions of conflicts. We here develop and test a model integrating ecological and human components of HWC, focusing on three species - opossum, crab-eating fox and puma. We investigated the pathways through which the ecological context (forest cover) affects experiences with wildlife (contact and damage), and how such experiences influence tolerance via beliefs, emotions and attitude. We interviewed 114 landowners across 13 landscapes varying in forest cover in a region of the Brazilian Atlantic forest and tested our model using Piecewise Structural Equation Modeling. We found that: i. forest cover negatively affected tolerance, but just towards the largest species; ii. relevance and effects of distinct experiences with wildlife on beliefs and emotions varied across species; iii. beliefs and emotions influenced tolerance, but negative emotions were relevant only for the largest species. Conflicts with larger species can then be understood as disservices provided by forests, indicating the relevance of framing HWC within a broader perspective that consider the trade-offs with ecosystems services. For some species, positive experiences with wildlife may counteract the negative effects of damages to livestock in shaping human behavior. Models such as ours - that structure relationships between ecological and human components - can help identifying deeper, more effective leverage points to improve interventions to mitigate HWC<br>Conflitos entre seres humanos e fauna silvestre emergem como desafios complexos, ameaçando o sustento de populações humanas e a conservação de populações de animais silvestres. Contudo, pesquisas sobre conflitos tradicionalmente abordam esses componentes separadamente e focam em espécies individuais ou similares, dificultando o entendimento mais amplo das conexões entre determinantes ecológicos e dimensões humanas dos conflitos. Neste estudo, desenvolvemos e testamos um modelo conceitual integrando componentes ecológicos e humanos dos conflitos, focando em três espécies - gambá, cachorro-do-mato e onça-parda. Investigamos os caminhos através dos quais o contexto ecológico (cobertura florestal) afeta experiências (contato e dano), e como tais experiências influenciam a tolerância à fauna por meio de crenças, emoções e atitude. Entrevistamos 114 proprietários rurais em 13 paisagens com diferentes proporções de cobertura florestal em uma região da Mata Atlântica e testamos nosso modelo usando equações estruturais do tipo Piecewise. Encontramos que: i. a cobertura florestal afetou negativamente a tolerância, mas apenas para a maior espécie; ii. a importância e os efeitos de diferentes experiências com a fauna sobre crenças e emoções variaram entre as espécies; iii. crenças e emoções influenciaram a tolerância, mas emoções negativas foram relevantes apenas para a maior espécie. Conflitos com espécies maiores podem então ser entendidos como desserviços providos por florestas, indicando a relevância de inserir os conflitos humano-fauna em perspectiva mais ampla, que considere as relações com serviços ecossistêmicos. Para algumas espécies, experiências positivas podem compensar os efeitos negativos dos danos a criações na formação do comportamento humano. Modelos como o nosso - que estruturem as relações entre os componentes ecológicos e humanos - podem ajudar a identificar pontos de alavancagem mais profundos e efetivos para melhorar intervenções visando a mitigação dos conflitos com a fauna

Some epithelial cancers can be induced to revert to quiescent differentiated tissues when combined with embryonic mesenchyme; however, the mechanism of this induction is unknown. This dissertation is based on the hypothesis that because extracellular matrix (ECM) plays a critical role during organ development in the embryo, it also may mediate the differentiation-inducing effects of embryonic mesenchyme on cancer cells. To test this hypothesis, I first optimized methods to isolate ECMs from whole tissues or cultured cells, and to repopulate them with cultured cells, using embryonic tooth as a model system. In Chapter 2, I describe these studies and use them to demonstrate that embryonic ECM is sufficient to regulate odontogenic signaling, cell fate decisions and histodifferentiation during normal tooth development. In Chapter 3, I adapt these methods to show that culture of breast cancer cells with ECM derived from embryonic mammary mesenchyme decreases tumor cell proliferation, and stimulates differentiation, including formation of hollow acini and ducts as well as enhanced expression of estrogen receptor-alpha and decreased migration. Further, when the inductive ECMs were injected into fast-growing breast tumors in mice, they significantly inhibited cancer expansion. Critically, the differentiation observed with ECM was the same as that observed in co-culture with mammary mesenchyme cells, showing that ECM is playing a dominant role in tumor cell normalization. In Chapter 4, I then set out to determine the mechanism by which embryonic ECM normalizes tumor cells, I analyzed the contributions of bound cytokines, ECM composition and mechanics. Western blot analysis revealed several bound growth factors, which remained following decellularization; however, removal of these growth factors using high salt washes had no effect on ECM-mediated normalization of tumors. Further, using proteomics analysis I identified eleven ECM proteins present only within inductive ECMs and by testing these proteins in 3D culture, I found three proteins -- collagen III, biglycan and SPARC -- that increased lumen formation to a similar extent as embryonic ECM. These data confirm that mesenchyme-induced tumor cell normalization is mediated by the insoluble ECM, and reveal the identity of some of the inductive molecules responsible for these effects.

Mestrado em Biologia Molecular e Celular<br>Objectivos: Os receptores tirosina cinase MET, ErbB-2 e EGFR foram identificados como tendo um papel importante no desenvolvimento e progressão de cancro. O objectivo deste estudo foi determinar a expressão e procurar interacções dos receptores MET, ErbB-2 e EGFR em linhas celulares de carcinomas de tiróide e mama, e em tumores mamários. Métodos: Neste estudo a expressão e interacções dos receptores MET, ErbB-2 e EGFR foi determinada em duas linhas celulares de carcinoma da tiróide (TPC-1 e 8505C) e em duas linhas celulares de carcinomas da mama (MDAMB- 231 e SkBr3). A expressão de MET foi também estudada, por Imunohistoquímica, numa serie de 219 carcinomas invasivos da mama, em microarrays, com um acompanhamento dos pacientes de 13 anos. Resultados: Observámos que MET, ErbB-2 e EGFR são expressos em todas as linhas de tiróide e mama, e observámos também interacções entre MET e ErbB-2. Na série de tumores mamários a expressão de MET foi significativamente relacionada com factores de prognóstico bem estabelecidos como ErbB-2, receptor de estrogénio, grau histológico e subtipos moleculares, sendo também significativamente associada com a diminuição da sobrevida das pacientes. Por análise multivariada MET demonstrou ter um valor prognóstico independente. Conclusões: O nosso estudo sugere que a comunicação entre MET e ErbB-2 pode ter um importante impacto clínico-patológico e que merece uma futura investigação, nomeadamente ao nível do desenvolvimento de novas terapêuticas. ABSTRACT: Aims: Receptor tyrosine kinases (RTKs) MET, ErbB-2 and EGFR have been identified to play an important role in cancer development and progression. Our aim was to determine MET, ErbB-2 and EGFR expression and search for their interactions in thyroid and breast carcinoma-derived cell lines and human breast tumours. Methods: We have studied the RTKs expression and interactions in two thyroid carcinoma-derived cell lines (TPC-1 and 8505C) and in two breast carcinomaderived cell lines (MDA-MB-231 and SkBr3). We have also studied, by Immunohistochemistry, MET expression on a series of 219 invasive breast carcinomas with 13-year disease follow, using tissue-microarray. Results: We observed that MET, ErbB2 and EGFR were expressed in both thyroid and breast cell lines, and we found physical interactions between MET and ErbB2. In the series of breast tumours, MET expression was significative correlated with established prognostic factors such ErbB-2, oestrogen receptor (ER), grade and subtype, and was also significatively associated with poor clinical outcome of the patients. By multivariate analysis MET showed to have an independent prognostic value. Conclusions: Our study suggests that the cross-communication between MET, and ErbB-2 may have clinicopathological impact and deserves further analysis namely in the design of novel combined therapeutic approaches.

Introduktion: Omkring 10–15% av nyblivna mammor drabbas av förlossningsdepression. Depression hos en nybliven mamma innebär förhöjd risk att relationen mellan henne och hennes nyfödda ej utvecklas optimalt. Då sköterskan på barnavårdscentralen har en kontinuerlig kontakt med nyfödda och deras mammor, kan de vara ett stöd i anknytningsprocessen. Syfte: Syftet med studien var att beskriva barnavårdscentralsköterskors reflektioner av att arbeta med mammor med förlossningsdepression och deras barn. Metod: Studien hade en beskrivande design med kvalitativ ansats. Data samlades in via åtta semistrukturerade intervjuer med barnavårdscentralsköterskor. Det insamlade materialet analyserades med en kvalitativ innehållsanalys. Huvudresultat:  Ett underliggande tema i studien var; ”Att använda sina kunskaper och inse sina begränsningar, för ett förtroendefullt samspel”. Temat bestod av fyra beskrivande kategorier; ”Vägar att upptäcka mammor med förlossningsdepression”, ”Interaktionen med mamman”, ”Strategier i arbetet” och ”Utmaningar med arbetet” Slutsats: Under studiens gång har det framkommit att om riktlinjer och rutiner ska fungera optimalt i arbetet med att upptäcka mamman med förlossningsdepression krävs en god kommunikation. Redan vid det första mötet med mamman började en resa som kunde innebära ett fungerande samspel eller en envägskommunikation. Detta krävde utöver formell kunskap om förlossningsdepression, en förmåga till interaktion med mamman.  Det handlade om att vinna mammans förtroende.<br>Introduction: About 10–15% of new mothers are affected by Post Partum Depression. A new mother with depression means a higher risk of attachmentsproblem with her newborn child. The child health care nurse has a regular contact with newborns and their mothers. Therefor they can have an important role in the process of attachment. Aim: The aim of the study was to describe reflections of the child health care nurses in their work with mothers with Postpartum Depression and their newborn. Method: The present study had a descriptive design with a qualitative approach. Eight child health care nurses  were interviewed with semi-structured interviews. The material was analyzied using qualitative content analysis. Result: A underlying theme was; ”To have knowledge and to know your limitations, for a trustworthy interaction.” The theme had four descriptive categories; ” Ways to discover the mother with a postpartum depression”, ”The interaction with the mother” ”Strategies at work” and ”Challenges in work”. Conclusion: During the study it has been revealed that if guidelines and routines are to work optimally discovering the mother with Post Partum Depression, it requires a good communication. Already at the first meeting a journey began, that could mean a working interaction or not. It required in addition to formal knowledge of Postpartum depression also an ability to interact with the mother. It was about getting the mother´s confidence.

Bovine fibroblasts and epithelial cells were isolated from surgically biopsied mammary tissue. Characterization of population doubling time, cytoskeletal intermediate filaments, cryopreservation survival, and viability were performed on all fibroblast and epithelial cells. Several clonal fibroblast cell lines were cotransfected with a plasmid bearing the SV-40 Large-T-antigen, and the pSV-2 neo plasmid. Transfected cells were subsequently selected with G418 sulfate and cloned.<br>MAC-T cells and non-clonal primary bovine mammary epithelial cells proliferated in response to IGF-I, insulin, serum and serum albumin. MAC-T cells did not proliferate when cultured in EGF, estrogen, progesterone, estrogen+progesterone, growth hormone, prolactin, and only modest proliferation was obtained after TGF-$ alpha$ treatment. Subsequent experiments used serum, insulin or IGF-I (and its analogues) to stimulate cellular proliferation. Serum albumin was not added to serum-free media preparations since it stimulated cellular proliferation.<br>TGF-$ beta$ receptors were characterized in MAC-T cells and normal fibroblasts. Affinity labelling studies revealed that MAC-T and MF-2 cells contained type I, II, and III autoregulatable receptors. Fibroblast proliferation, was inhibited 50% by TGF-$ beta$. TGF-$ beta$ inhibited MAC-T cellular proliferation at concentrations among the lowest ever reported, ED$ sb{ rm 50}$ = 4 pm. TGF-$ beta$ was not cytotoxic at concentrations 1000-fold higher.<br>Retinoic acid (RA) also inhibited proliferation of MAC-T cells. Inhibition of proliferation did not occur when cells were growth stimulated by IGF-I analogues that do not bind IGFBPs. Unlike TGF-$ beta$, RA treatment increased IGFBP-2 and decreased IGFBP-3 protein expression by cells into media and on the cell's membrane. RA was cytotoxic at concentrations 10-fold higher than ED$ sb{100}$.<br>Fibroblasts and epithelial cells expressed the gap junction (GJ) protein, connexin43, with transformed fibroblasts expressing significantly less connexin43. Perinuclear and cell surface connexin43 was immunodetected in epithelial and fibroblasts cells. TGF-$ beta$, RA or cAMP, increased connexin43 protein expression, especially phosphorylated species. Only cAMP noticeably altered immunolocalization patterns of connexin43, causing a shift from perinuclear pools to the cell surface. None of the growth inhibitors affected GJ communication as measured by dye transfer. Therefore, mammary epithelial cells are growth inhibited by TGF-$ beta$ and RA by distinct mechanisms and both growth inhibitors significantly enhance the gap junction protein, connexin43, without increasing GJ communication.

CLCA2 is a p53-inducible transmembrane protein that is frequently downregulated in breast cancer. CLCA2 is a 943 amino acid type I transmembrane protein that is cleaved near amino acid 700 to produce a diffusible 100kD product. The N-terminus contains a hydrolase-like domain with well-conserved HEXXH zinc binding amino acid motif that was proposed to cleave the precursor auto-proteolytically. We investigate the auto-proteolysis of CLCA2 precursor. Using membrane extracts or purified protein from CLCA2-transfected cells, we show here that CLCA2 cleavage is catalyzed by zinc and inhibited by metal chelator EDTA. Moreover, an E165Q mutation in the metal binding site abolished processing without affecting stability or trafficking. The mutant could be cleaved by co-transfected wild type CLCA2, showing that the mutation had not caused an un-cleavable conformation and suggesting that it occurs in trans. Wild type CLCA2 was able to cleave CLCA2 E165Q mutant in vitro only after denaturation and renaturation, suggesting that a conformational shift is required for cleavage. The efficiency of cleavage increased steeply with increasing concentration of precursor, consistent with trans proteolysis but not cis or cleavage by another agent. Accordingly, CLCA2 molecules bearing different epitope tags formed a stable complex that could be co-immunoprecipitated. Cleavage appears to be specific within isoforms; CLCA1 was unable to neither cleave CLCA2 nor form a stable complex with it. Furthermore, cleavage causes a conformational shift: an N-terminal antibody that immunoprecipitates the precursor fails to precipitate the N-terminal product unless it is first denatured with ionic detergent. We found that cleavage is enhanced by p53 induction due to DNA damage, implying that the cleavage has functional consequences for stress response. Moreover, we found that HEK and MCF10A cells expressing the E165Q mutant had a higher proliferation rate than cells expressing wild type CLCA2, suggesting that the metalloprotease activity contributes to the anti-proliferative effect of CLCA2. Physiologically, CLCA2 plays an essential role in epithelial differentiation. It is induced during epithelial differentiation in immortalized human mammary epithelial cells (HMEC), and its knockdown causes epithelial to mesenchymal transition (EMT). To determine how CLCA2 promotes epithelial differentiation, we searched for interactors using membrane dihybrid screening. We discovered a strong interaction with Epithelial V-like Antigen 1 (EVA1) and confirmed by co-immunoprecipitation. Like CLCA2, EVA1 is a type I transmembrane protein that is regulated by p53 family. EVA1 resembles tight junction proteins called Junctional Adhesion Molecules (JAMs) by structure but we found by confocal analysis that EVA1 is localized the lateral interface at cell-cell junctions. Analysis of transcriptional profiles revealed that EVA1 is frequently downregulated in breast tumors and breast cancer cell lines, especially those of mesenchymal phenotype, and upregulated during epithelial differentiation. Like CLCA2, knockdown of EVA1 resulted in rapid EMT in immortalized HMEC. The interacting domains were delimited by deletion analysis, revealing that both the proteins interact via their transmembrane segments (TMS). The interaction was specific, as other transmembrane proteins did not interact with CLCA2 or EVA1. We also found that CLCA2 binds to ZO-1 and beta-catenin at its c-terminus but EVA1 does not. Interestingly, we found that EVA1 does interact with ZO-1 in the presence of CLCA2, indicating that these three form a complex at the cell-cell junctions that allows stabilization of belt-like adherens junctions (AJ). On the other hand CLCA2 may also stabilize adherens junctions by sequestering beta-catenin at the cell-cell junctions. These results indicate that CLCA2 plays a key role in maintaining epithelial differentiation via multiple ways. Either by binding to beta-catenin or forming a complex with EVA1 and ZO-1, it plays a pivotal role in maintaining epithelial differentiation. This explains the downregulation of both CLCA2 and EVA1 during tumor progression.

Human breast cancer (HBC), canine (CMT), and feline mammary tumors (FMT) are extremely common and are characterized by a remarkable both inter- and intra-tumor heterogeneity. Intra-tumor heterogeneity is due to the coexistence of cancer cells that differ between each other in terms of phenotypic, genetic, behavioral characteristics, and metastatic potential. Cancer stem cells (CSCs) are thought to be responsible for such heterogeneity, resistance to therapy, and metastasis development. Several pathways are altered in CSCs, such as the oncogenic Wnt/-catenin and Hippo pathways, and CSCs are associated to the epithelial-to-mesenchymal transition (EMT) process. The aims of this study were to i) isolate and characterized mammary CSCs; ii) investigate EMT process and Wnt/-catenin and Hippo pathways in mammary cancer of the three species; iii) establish a metastatic mouse model of breast cancer seeking for genes responsible of metastatic dissemination; iv) isolate and characterize extracellular vesicles (EVs), which is one of the main forms of intercellular communication, from canine and feline mammary tumors as well as study the role that EVs play during tumor development. CSC-like cells were isolated from established canine and feline mammary tumor cell lines (CYPp and FMCp, respectively) and phenotypically and molecularly characterized for common CSC markers: CD44, CD24, CD133, SOX2, OCT4. Moreover, gene (qPCR) and protein (IHC and WB) expression of Wnt/-catenin and Hippo pathways-related molecules (-catenin, CCND1, YAP, TAZ, CTGF, ANKRD1) as well as protein expression (IHC) of EMT-related molecules (E-cadherin, SNAIL, TWIST, ZEB) were evaluated in a subset of human, canine, and feline mammary cancer tissues, that were also phenotypically characterized for the following markers: CK8/18, CK5/6, CK14, CD44, and vimentin. Additionally, triple negative breast cancer (TNBC) cell line MDA-MB-231 was used to establish a clinically relevant in vivo metastatic model. Finally, EVs were isolated and characterized from CYPp and FMCp and human glioblastoma-derived EVs were used to study tumor angiogenesis. We found that CD44, CD133, SOX2, and OCT4 expression increase in CSC-like cells (mammospheres) compared to parental adherent cells, therefore they could be used as useful markers in CMTs and FMTs. Wnt/-catenin and Hippo pathways seem to be deregulated at a post-transcriptional level in HBCs, CMTs, and FMTs. Interesting similarities were confirmed between TNBCs and FMTs, as well as between ER+ HBC and CMTs. In our metastatic model, mice developed distant metastases and we found a few genes that might play a role during metastatic dissemination. Among these, caspase 3 seems to be involved in brain metastases. Additionally, EVs were isolated from CYPp and FMCp, visualized by transmissible electron microscopy, counted using nanoparticle tracking analysis, and characterized by immunogold and WB (Alix, CD63, TSG101). Finally, using a human glioblastoma cell line (GBM8) we demonstrated that EVs are directly involved in tumor angiogenesis. Overall, this study confirms the use of dogs and cats as spontaneous models of mammary cancer development due to highly interesting biological similarities among the three species. Also, identification of EVs in CMTs and FMTs opens an interesting unexplored field in veterinary medicine.<br>Human breast cancer (HBC), canine (CMT), and feline mammary tumors (FMT) are extremely common and are characterized by a remarkable both inter- and intra-tumor heterogeneity. Intra-tumor heterogeneity is due to the coexistence of cancer cells that differ between each other in terms of phenotypic, genetic, behavioral characteristics, and metastatic potential. Cancer stem cells (CSCs) are thought to be responsible for such heterogeneity, resistance to therapy, and metastasis development. Several pathways are altered in CSCs, such as the oncogenic Wnt/-catenin and Hippo pathways, and CSCs are associated to the epithelial-to-mesenchymal transition (EMT) process. The aims of this study were to i) isolate and characterized mammary CSCs; ii) investigate EMT process and Wnt/-catenin and Hippo pathways in mammary cancer of the three species; iii) establish a metastatic mouse model of breast cancer seeking for genes responsible of metastatic dissemination; iv) isolate and characterize extracellular vesicles (EVs), which is one of the main forms of intercellular communication, from canine and feline mammary tumors as well as study the role that EVs play during tumor development. CSC-like cells were isolated from established canine and feline mammary tumor cell lines (CYPp and FMCp, respectively) and phenotypically and molecularly characterized for common CSC markers: CD44, CD24, CD133, SOX2, OCT4. Moreover, gene (qPCR) and protein (IHC and WB) expression of Wnt/-catenin and Hippo pathways-related molecules (-catenin, CCND1, YAP, TAZ, CTGF, ANKRD1) as well as protein expression (IHC) of EMT-related molecules (E-cadherin, SNAIL, TWIST, ZEB) were evaluated in a subset of human, canine, and feline mammary cancer tissues, that were also phenotypically characterized for the following markers: CK8/18, CK5/6, CK14, CD44, and vimentin. Additionally, triple negative breast cancer (TNBC) cell line MDA-MB-231 was used to establish a clinically relevant in vivo metastatic model. Finally, EVs were isolated and characterized from CYPp and FMCp and human glioblastoma-derived EVs were used to study tumor angiogenesis. We found that CD44, CD133, SOX2, and OCT4 expression increase in CSC-like cells (mammospheres) compared to parental adherent cells, therefore they could be used as useful markers in CMTs and FMTs. Wnt/-catenin and Hippo pathways seem to be deregulated at a post-transcriptional level in HBCs, CMTs, and FMTs. Interesting similarities were confirmed between TNBCs and FMTs, as well as between ER+ HBC and CMTs. In our metastatic model, mice developed distant metastases and we found a few genes that might play a role during metastatic dissemination. Among these, caspase 3 seems to be involved in brain metastases. Additionally, EVs were isolated from CYPp and FMCp, visualized by transmissible electron microscopy, counted using nanoparticle tracking analysis, and characterized by immunogold and WB (Alix, CD63, TSG101). Finally, using a human glioblastoma cell line (GBM8) we demonstrated that EVs are directly involved in tumor angiogenesis. Overall, this study confirms the use of dogs and cats as spontaneous models of mammary cancer development due to highly interesting biological similarities among the three species. Also, identification of EVs in CMTs and FMTs opens an interesting unexplored field in veterinary medicine.

The Cape Horn Biosphere Reserve is located at the southern tip of South America. This large archipelago is considered one of the last pristine areas left on the world. Despite it being an unpopulated area with most of the native forest cover intact, it has not been exempt from biological invasions, one of the major drivers of biodiversity loss. Three species that naturally interact in their native range in North America – American beavers (Castor canadensis), muskrats (Ondatra zibethicus), and American mink (Neovison vison) – were independently introduced in this remote region. In my dissertation, I investigated (i) the hypothesis of niche expansion in the invasive mink population on Navarino Island towards terrestrial habitats; (ii) potential mink impact on breeding success of forest-bird populations; (iii) habitat selection of small-rodent species and their perception on the mink's novel predation risk; and (iv) the dynamics of multiple-species invasions under the hypothesis of an invasional meltdown. Additionally, I worked within the framework of environmental philosophy. I provide an example of combining ecological and cultural dimensions within the International Long-Term Ecological Research network to disentangle the ethical dilemmas that surround the management of invasive species. I finally proposed a management plan based on the idea of multiple invasive species management, discussing potential solutions to overcome the challenges that the control of invasive species represent and to more effectively protect the biological integrity of the native ecosystems.

Les proteoglycanes composes de chaines de chondroitine sulfate isoles de la media-intima d'aorte de porc possedent une affinite pour la lipoproteine lipase purifiee a partir du lait de vache. Etude du complexe enzyme-proteoglycanes marque a l'iode 125

Dissertação (mestrado)—Universidade de Brasília, Faculdade Gama, Programa de Pós-Graduação em Engenharia Biomédica, 2015.<br>Submitted by Fernanda Percia França (fernandafranca@bce.unb.br) on 2016-03-11T18:10:28Z No. of bitstreams: 1 2015_DanieldeSouzaBraga.pdf: 26329045 bytes, checksum: 198bb14740fdbbf67ef13fc1a02502e0 (MD5)<br>Approved for entry into archive by Patrícia Nunes da Silva(patricia@bce.unb.br) on 2016-05-27T14:19:02Z (GMT) No. of bitstreams: 1 2015_DanieldeSouzaBraga.pdf: 26329045 bytes, checksum: 198bb14740fdbbf67ef13fc1a02502e0 (MD5)<br>Made available in DSpace on 2016-05-27T14:19:02Z (GMT). No. of bitstreams: 1 2015_DanieldeSouzaBraga.pdf: 26329045 bytes, checksum: 198bb14740fdbbf67ef13fc1a02502e0 (MD5)<br>O estudo da anatomia humana é essencial na prática clínica, exame físico, exames radiológicos, cirurgia e na reabilitação física, assim, torna-se parte inseparável da educação em saúde. O prognóstico de doenças, como o câncer de mama, pode ser mais favorável se identificado e tratado precocemente, o que exige uma maior atenção nos centros de pesquisas, programas governamentais e organismos internacionais para o desenvolvimento de tecnologias que auxiliem no aprimoramento dos métodos de detecção, tratamento e treinamento clinico. O objetivo desse estudo foi implementar uma Rede Neural Artificial (RNA) do tipo Interactive Activation and Competition (IAC) utilizando a Arquitetura Orientada a Serviço (AOS) para auxiliar o estudo de conteúdos da anatomia da mama feminina para estudantes da graduação da área da saúde. Foram disponibilizados textos, imagens, vídeos e interações com modelos em terceira dimensão (3D) para o entendimento das estruturas externas e internas da mama feminina. Foi aplicado aos 29 participantes do curso de Fisioterapia da Universidade Católica de Brasília (UCB) um questionário após a utilização do sistema de tutoria. Constatou-se que os estudantes percebem o ensino e aprendizagem com as seguintes distribuições em relação a recursos tecnológicos: Vídeos (37%), Imagens (33%), 3D (19%) e Textos (11%), além da expansão do conteúdo de Anatomia da Mama Feminina para Afecções (47%) e Doenças (33%). Esse trabalho gerou dois aplicativos, isto é, a Plataforma de RNA IAC Orientada a Serviço (PRIS), que implementa uma RNA IAC com igual distribuição de valores (teste de hipótese não paramétrico de Mann-Whitney) em comparação com a ferramenta de simulação PDPTools (p-value = 0,96 > α = 0,05), e o sistema Anatomia da Mama Feminina (ANAMAMA), um gerenciador de conteúdo para a área de anatomia da mama feminina. ___________________________________________________________________________ ABSTRACT<br>The study of human anatomy is essential in clinical practice, physical examination, radiological examinations, surgery and physical rehabilitation, then, it becomes an inseparable part of health education. The prognosis of diseases such as breast cancer, may be more favorable if identified and treated early, which requires a greater attention in research centers, government programs and international organizations for the development of technologies assisting in the improvement of detection methods, treatment and clinical training. The purpose of this paper was to implement an Artificial Neural Network (ANN) type Interactive Activation and Competition (IAC) using a Service Oriented Architecture (SOA) to assist the contents of study of the female breast anatomy to undergraduate students in the health field. Texts, images, videos and interactions with three-dimension models (3D) to understand the external and internal structures of the female breast were made available. After using the tutoring system a questionnaire was applied to the 29 participants of the Physiotherapy course of the Catholic University of Brasilia (UCB). It was observed that students perceive teaching and learning with the following distributions in relation to technological resources: Videos (37%), Images (33%), 3D (19%) and Texts (11%), in addition to the expansion of content of Female Breast Anatomy for Disorders (47%) and Diseases (33%). Such paper led to two applications, namely, ANN IAC Service Oriented Platform (PRIS), which implements an ANN IAC with equal value distribution (Mann-Whitney´s non-parametrical hypothesis test) compared with the simulation tool PDPTools (p-value = 0.96 > α = 0.05), and the Female Breast Anatomy system (ANAMAMA), a content manager for the anatomy of the female breast area.

Les membres de la famille RHO de GTPpases monomériques sont des interrupteurs moléculaires impliqués dans la transduction de nombreux signaux aboutissant notamment à la motilité cellulaire et à la transcription de gènes. Notre travail a porté sur le complexe formé entre la protéine G RHO et RHO-GDI, son régulateur naturel. Les deux protéines sont associées dans le cytosol mais il est nécessaire qu'elles soient séparées pour que RHO puisse exercer sa fonction. Nous nous sommes intéressés aux stimuli permettant d'activer leur protéine G à partir de son complexe avec RHO-GDI. Nous avons d'abord mis au point dans un système d'expression eucaryote la production de complexes formés in vivo entre les GTPases de la famille RHO et RHO-GDI. La purification de ces complexes a abouti à la production de cristaux et devrait permettre l'étude de leurs structures tridimensionnelles. Nous avons utilisé ces complexes pour étudier l'effet des phosphoïnositides sur l'état d'association de RHO avec RHO-GDI. Nous avons montré que ces lipides induisaient une conformation pré-activée du complexe, sans toutefois dissocier les deux partenaires. La méthode double-hybride nous a permis de cloner par interaction avec RHO-GDI l'ensemble des membres de la famille RHO ainsi que plusieurs régulateurs potentiels. Cette methode a ensuite servi à étudier les zones de RHO susceptibles d'interagir avec RHO-GDI grâce à la production de mutants de RHOA. L'interaction entre la GTPase RHO et RHO-GDI met en oeuvre un résidu isoprène lié à l'extrémité c-terminale de RHO. Les mutants de RHOA ne portant pas ce résidu sont cependant toujours capables d'interagir avec RHO-GDI, vraissemblablement grâce à la zone d'insertion de RHO. Enfin, une technique d'overlay a été utilisée pour mettre en évidence des partenaires membranaires du complexe RHO/RHO-GDI activé par les phosphoïnositides. Une protéine de 32kda, lâchement attachée à la membrane, a ainsi été isolée comme régulateur potentiel du complexe RHO/RHO-GDI.

The effect of shared enemies between invasive and native species has been argued to facilitate biological invasions (i.e., the apparent competition hypothesis or ACH). This study investigated a previously untested possibility: whether granivorous small mammals facilitate cheatgrass (Bromus tectorum) invasion by driving food-mediated apparent competition between cheatgrass and native grasses. Specifically, we tested three predictions that must be true if such apparent competition occurs. First, cheatgrass invasion augments total seeds available to granivorous small mammals. Second, density of granivorous small mammals increases in response to increased seed availability (simulated with experimental additions of cheatgrass seeds). Third, granivorous small mammals prefer seeds from native grasses over cheatgrass seeds. We tested these predictions in the Great Basin Desert of Utah, USA. Cheatgrass invasion augmented total yearly seed production. Granivorous small mammals preferred native seeds over cheatgrass seeds. However, neither abundance, richness, nor diversity of granivorous small mammals increased in response to experimental additions of cheatgrass seed. We therefore conclude that granivorous small mammals did not drive food-mediated apparent competition during the study period. The lack of support for the ACH in this study may suggest that the role of small mammal-driven apparent competition is either unimportant in the Great Basin, or that the appropriate indirect interactions between small mammals, cheatgrass, and native grasses have yet to be evaluated. Testing the third prediction required the separation of seeds from the soil matrix. We employed a chemical flotation methodology to recover target seeds from soil, and developed a novel method of decanting target material from the flotation solution. We compared the utility of the novel method to that of a traditional decantation method. Specifically, we compared effectiveness (the proportion of seeds recovered from a known sample), rapidity (the time required to decant that sample), efficiency (the number of seeds decanted per second), and recovery bias (the effect of relative density on seed recovery) between methods. Our proposed method was more effective, more rapid, more efficient, and less biased than the traditional method. Therefore, any future work relying on flotation to analyze seed banks should clearly describe how samples are decanted and should consider the proposed method as a potential means of enhancing the efficiency of chemical flotation.

Preparation et caracterisation de porphyrines cationiques dont le nombre et la position des charges varient. Cytotoxicite vis-a-vis des cellules l1210 et de bacteries sensibles aux intercalants et deficients ou non dans leurs systemes de reparation de l'adn

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2017-03-14T18:51:10Z No. of bitstreams: 1 texto completo.pdf: 943385 bytes, checksum: 8adee72c3a2e9d49512f689910c76c69 (MD5)<br>Made available in DSpace on 2017-03-14T18:51:10Z (GMT). No. of bitstreams: 1 texto completo.pdf: 943385 bytes, checksum: 8adee72c3a2e9d49512f689910c76c69 (MD5) Previous issue date: 2016-12-09<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Mastite causada por Escherichia coli tem a capacidade de estimular intensamente o sistema imunológico e desencadear rapida inflamação na glândula mamária. Em contraste, Mycobacterium avium subsp. paratuberculosis (MAP), agente etiológico da paratuberculose, caracterizada por enterite granulomatosa crônica, pode infectar a glândula mamária sem estimular intensamente a resposta inflamatória. A interação dessas duas bactérias na glândula mamária ainda é desconhecida. Em alguns casos, tanto a eliminação de MAP pelo leite como pelas fezes podem ocorrer de forma passiva, após a infecção ascendente da glândula mamária ou após ingestão de MAP, respectivamente. Estes animais, chamados passive-shedders, são importantes como uma fonte de infecção a animais suscetíveis no rebanho. O objetivo deste estudo foi investigar a relação entre MAP e E. coli em células de glândula mamária sob condições experimentais e verificar a presença de animais passive-shedders. A relação entre uma cepa K-10 de MAP e E. coli isolada de leite mastítico em linhagem de células epiteliais mamárias (MAC-T) foi avaliada. As células previamente infectadas com MAP diminuíram a invasão de E. coli durante 120 min de experimentação. Contudo, a eficiência da translocação de E. coli e a viabilidade das células MAC-T não foram comprometidas. Ao contrário, células previamente infectadas por E. coli aumentaram a capacidade de translocação baso-apical de MAP até os 30 min e diminuiu aos 120min pós-infecção. A quantificação de citocinas relevou que a expressão de IL-1β aos 120min foi significativa (P<0.05) para células infectadas por MAP + E. coli e E. coli apenas. As expressões de MAPKp 38 e IL-10 não foram significativas, independente do tempo pós-infecção. Para detectar a ocorrência de animais passive-shedders, 10 propriedades foram previamente investigadas para a presença de MAP. Treze cabras foram positivas por cultura de fezes e/ou PCR de leite. Dentre os animais positivos, quatro (4/13) foram adquiridas e avaliados por IS900-PCR, cultura de fezes, de leite e de tecido, e sorologia (ELISA). Todos os resultados foram negativos no período de um ano, demonstrando que os animais realizaram o fenômeno pass-through e a contaminação ascendente da glândula mamária, sem tornarem-se infectados. No geral, esses resultados indicam que a presença de MAP nas células mamárias pode dificultar a capacidade de invasão de E. coli, mas quando no interior da célula mamária, translocam-se mais eficientemente. No entanto, quando as células são previamente infectadas por E. coli, MAP é rapidamente atraído da região subepitelial para a superfície celular. A produção de IL-1β intensifica a atração de macrófagos para o sítio de infecção, onde MAP se beneficia, infectando-os.<br>Mastitis caused by Escherichia coli can intensely stimulate the immune system and rapidly trigger inflammation in the mammary gland. In contrast, Mycobacterium avium subsp. paratuberculosis (MAP), the etiological agent of paratuberculosis, characterized by chronic granulomatous enteritis, can infect the mammary gland without intensely stimulating the inflammatory response. The interaction of these two species in the mammary gland is still unknown. In some cases, both the elimination of MAP by milk and faeces may occur passively, either through ascending infection of the mammary gland or through ingestion of MAP, respectively. These animals are called passive- shedders and are important as a source of infection to susceptible animals in the herd. The aim of this study was to investigate the relationship between MAP and E. coli in mammary gland cells under experimental conditions and verify the presence of passive- shedder animals. The relationship between a K-10 strain of MAP and E. coli isolated from mastitic milk in mammary epithelial cell lines was evaluated. Cells previously infected by MAP decreased E. coli invasiveness during 120min experimentation. However, the efficiency of E. coli translocation was not compromised, nor was the viability of the MAC-T cells. In contrast, cells previously infected by E. coli showed increased basal-apical translocation capacity of MAP up to 30 min and decreased at 120 min postinfection. Quantification of cytokines showed that IL-1β expression at 120 min was significantly increased in cells infected by MAP + E. coli and E. coli only. Expression of MAPKp 38 and IL-10 were not significant, regardless of time postinfection. To determine the occurrence of passive-shedders, 10 properties were previously investigated for MAP detection. Thirteen goats were positive by faeces culture and/or milk PCR. Among the positive animals, four (4/13) were evaluated by IS900-PCR, feces culture, milk and tissue culture and serology (ELISA). All the results were negative over a one-year period, demonstrating that the animals performed pass- through phenomenon and upward contamination of the mammary gland without becoming infected. Together, these results indicate that the presence of MAP in mammary cells may hamper capacity of E. coli invasion, but when within the mammary cell, the bacteria evade more efficiently. However, when the cells are pre-infected by E. coli, MAP is rapidly attracted from the subepithelial region to the cell surface. IL-1β production enhances the attraction of macrophages to the site of infection, where MAP benefits by infecting them.

L'IFN induit, à la surface des kératinocytes, l'expression de l'icam-1 qui est un ligand de l'intégrine lfa-1 exprimée à la surface des lymphocytes actives. Ces deux molécules sont impliquées dans l'adhérence des lymphocytes sur les kératinocytes traites par L'IFN, mais l'interaction entre l'icam-1 et lfa-1 ne rend pas compte à elle seule de toute cette adhérence. En effet, nous avons montré que l'adhérence des lymphocytes n'est pas totalement inhibée lorsque les kératinocytes actives par L'IFN ou les lymphocytes actives par le PMA sont préincubes, respectivement, en présence d'anticorps anti-icam-1 ou anti-lfa-1. Ces résultats suggèrent la participation d'autres molécules d'adhésion dans l'interaction kératinocytes/lymphocytes. Nos résultats montrent un rôle important des intégrines de la famille 1, exprimées aussi bien sur les lymphocytes que les kératinocytes dans cette adhérence. Nous avons en particulier montre un rôle majeur des intégrines 31 et 21. Parallèlement, L'IFN diminue l'expression des intégrines de la famille 1 à la surface des kératinocytes. La régulation de l'expression des intégrines 1 par L'IFN met en jeu des tyrosines kinases et des protéines kinases c alors que l'expression de l'icam-1 fait intervenir les protéines kinases calcium calmoduline dépendantes. L'étude des mécanismes d'action de L'IFN, a permis l'identification de différents seconds messagers induits par cette cytokine dans les kératinocytes. Ainsi, L'IFN induit une augmentation du contenu en inositolphosphates, dans les kératinocytes après 1 minute d'activation. Une autre voie de transduction a aussi été mise en évidence : la voie dépendante des glycosylphosphatidylinositols. Par ailleurs, L'IFN inhibe totalement l'expression de l'intégrine 51 présente à la surface des kératinocytes normaux et entraine une perte d'adhérence des cellules sur la fibronectine. Ces différents évènements cellulaires sont contrôlées par l'activation d'une protéine kinase c.

Människors olikheter bemöts ofta med fördomar och stereotypa uppfattningar, men detär av största vikt att förstå att ingen människa är en funktionsvariation, utan en unikindivid med en unik personlighet. Denna studies syfte var att få en djupare förståelse förhur mammor till barn med autismdiagnos upplever samt känslomässigt ochbeteendemässigt hanterade hur allmänheten bemötte deras barn. Studiens resultatkopplades an till Goffmans teorier om face samt stigma och motstrategier till stigma.Studien hade en kvalitativ fenomenologisk inriktning och var uppbyggd påsemistrukturerade intervjuer med 10 stycken mammor till barn med autismdiagnos.Resultatet visade att mammor till barn med autismdiagnos upplevde både negativa ochpositiva bemötanden gentemot barnen. Negativa bemötanden ledde till negativa känslorhos mammorna, medan positiva bemötanden ledde till positiva känslor. Dock kundeman se en majoritet av negativa bemötanden. Mammornas hantering av ett negativtbemötande från omgivningen tog sig uttryck i att försvara eller hjälpa sitt barn, eller attlämna, alternativt välja bort den sociala interaktionen. Slutligen kunde konstateras attdet på mikronivå fortfarande fanns mycket att göra för att främja känslan av acceptansför olikheter i samhället.<br>Human differences are often addressed with prejudices and stereotypical perceptions,but it is important to understand that no one is their disability, but a unique individualwith a unique personality. The purpose of this study was to gain a deeper understandingof how mothers of children with autism experienced, and emotionally and behaviorallydealt with how the public responded to the children. The results of the study were linkedto Goffman's theories about face, stigma and counter strategies to stigma. The study hada qualitative phenomenological focus and was based on semistructured interviews with10 mothers of children with autism. The result showed that mothers of children withautism experienced both negative and positive responses towards the children. Negativeresponses led to negative emotions, while positive responses led to positive emotions.However, one could see a majority of negative receptions. How the mothers dealt withnegative response from the environment was expressed in defending or helping herchild, alternatively leaving the social interaction. Finally, it was found that at a microlevel there was still a lot to do to promote the sense of acceptance for differences insociety.

L'objectif de ce travail est de comparer la liaison et les effets biologiques de l'hormone de croissance (gh) 1) dans les adipocytes du tissu inguinal de jeunes rats zucker obeses fa/fa et minces fa/fa; 2) dans les preadipocytes de rats zucker en culture primaire au cours de la differenciation adipocytaire. 1. Les etudes de liaison de la gh et les courbes dose-reponse pour le transport et le metabolisme du glucose sont realisees avec des adipocytes soit fraichement isoles (f) soit preincubes 3 h (p)

Esta tesis doctoral es una investigación aplicada a la comunicación en un grupo psicoterapéutico con mujeres que han superado un cáncer de mama. Se diseña una matriz terapéutica, GAFA (Analítica, Formativa y de Ayuda social), que combina las potencialidades de las tres modalidades de intervención, y propicia un proceso de ayuda interactiva basada en la implicación de las participantes, desde la escucha y el habla dialogada, y en el señalamiento y la elaboración discusiva de los nudos biográficos a través de la comunicación grupal. El funcionamiento del grupo, cuya primera convocatoria ha contado con siete mujeres participantes y la terapeuta, se ha estudiado utilizando la metodología observacional que incorpora el análisis cuantitativo y cualitativo de la interacción. A lo largo de nueve sesiones de noventa minutos de duración se ha codificado la conducta interactiva verbal y no verbal en el contexto de la tarea GAFA. Comprobado el grado de concordancia entre observadores (>80%), los resultados confirman la utilidad del método GAFA (implicar a las mujeres curadas de cáncer de mama en un proceso de normalización de la propia vida), y apoyan la idea de que el esfuerzo por sobrevivir (resiliencia), que se alimenta de esperanza (perspectiva de futuro) y sensibilidad relacional (conciencia interpersonal), necesita ser verbalizado como entrega que se abre a la palabra (crítica) del otro. Los procesos interactivos vinculados a los movimientos de fase, dentro de cada reunión, y a la experiencia acumulada (número de sesiones rodadas) de las participantes, se identifican y se describen como patrones secuenciales (análisis secuencial). El carácter descriptivo de esta investigación nos autoriza a mantener, mejorar, modificar y complementar la arquitectura del método GAFA, de acuerdo con el estudio realizado. Palabras clave: curación del cáncer de mama, psicoterápia de grupo, análisis de la interacción, patrones de ayuda, análisis del contenido referencial.<br>Aquesta tesi doctoral és una investigació aplicada a la comunicació dins un grup psicoterapèutic amb dones que han superat un càncer de pit. Es dissenya una matriu terapèutica, GAFA (Analítica, Formativa i d’Ajuda social), que combina les potències de les tres modalitats d’intervenció i propicia un procés d’ajut interactiu basat en la implicació de les participants, des de l’escolta i la parla dialogada i la indicació i l'elaboració discussiva dels nusos biogràfics mitjançant la comunicació grupal. El funcionament del grup, la primera convocatòria del qual ha comptat amb set dones participants i la terapeuta, ha estat estudiat fent servir la metodologia observacional que comporta l’anàlisi quantitativa i qualitativa de la interacció. Al llarg de nou sessions de noranta minuts cadascuna, s’ha codificat la conducta interactiva verbal i no verbal dins el context de la tasca GAFA. Un cop comprovat el grau de concordança entre els observadors (>80%), els resultats confirmen la utilitat del mètode GAFA (implicar dones curades de càncer de pit en un procés de normalització de les seves vides) i recolzen la idea que l’esforç per sobreviure (resiliència), que es nodreix d’esperança (perspectives de futur) i sensibilitat relacional (conciència interpersonal), necessita ésser verbalitzat en tant que entrega que s’obre a la paraula (crítica) de l’altre. Els processos interactius vinculats als moviments de fase, dins de cada reunió, i a l’experiència acumulada (nombre de sessions rodades) de les participants s’identifiquen i es descriuen com a patrons seqüencials (anàlisi seqüencial). El caràcter descriptiu de la present investigació ens autoritza a mantenir, millorar, modificar i completar l’arquitectura del mètode GAFA, d’acord amb l’estudi portat a terme. Paraules clau: curació del càncer de pit, psicoteràpia de grup, anàlisi de la interacció, patrons d’ajuda, anàlisi del contingut referencial.

Un accroissement de la motricité utérine est induit par 2 inhibiteurs de l'enképhalinase: l'Acétorphan et le Thiorphan chez la rate au 21ème jour de la gestation. Elévation des prostaglandines F2 alpha et E2 et décroissance du Bêta -Oestradiol

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico<br>FAPEMIG - Fundação de Amparo a Pesquisa do Estado de Minas Gerais<br>A agregação de parasitas em determinados indivíduos da população de hospedeiros está associada à exposição e à suscetibilidade diferenciais, que variam de acordo com o sexo, o tamanho corporal, a condição reprodutiva, o comportamento de uso do espaço (que influencia a probabilidade de capturas e recapturas em diferentes locais) e os fatores ambientais. Desse modo, o objetivo desse estudo foi avaliar a influência de tais fatores sobre a infecção de Eimeria spp. (endoparasita intestinal) em Gracilinanus agilis, um marsupial didelfídeo semélparo neotropical. O local de coletas foi um fragmento de cerrado sentido restrito na Estação Ecológica do Panga, MG, entre 2011 a 2015. Foi utilizado um método de capturamarcação- recaptura para os hospedeiros e avaliada a prevalência e a abundância do parasita, por meio de análises fecais laboratoriais. A abundância e a prevalência de Eimeria spp. foram associadas, principalmente, à condição reprodutiva dos indivíduos, com ambos os sexos apresentando maior prevalência e alta abundância parasitária durante o final do período reprodutivo, que coincide com a época chuvosa. Machos apresentaram mais parasitas do que as fêmeas durante a estação seca, época de início do período reprodutivo, no qual o acasalamento ocorre. Não foi comprovada a hipótese de que a maior abundância de parasitas nos machos seria decorrente de seu maior deslocamento espacial. No entanto, o número de recapturas de G. agilis correlacionou-se significativamente com a abundância de Eimeria spp. Esse padrão pode ser explicado pelo maior contato do marsupial com suas próprias fezes, as quais transmitem os parasitas, como também pelo aumento do estresse ocasionado pelo aprisionamento na armadilha, que afeta negativamente a eficiência do sistema imunológico. Assim, a presença e a abundância de Eimeria spp. ao longo do período reprodutivo em ambos os sexos, parece estar mais associada com a susceptibilidade do hospedeiro do que com sua exposição, visto que não houve relação entre mobilidade e infecção. Porém, as medidas de deslocamento nesse estudo devem ser avaliadas com cautela, dado o baixo número de recapturas utilizado para estimativa do uso do espaço em G. agilis.<br>The aggregation of parasites in certain individuals of the host population is associated with differential exposure and susceptibility, which vary according to sex, body size, reproductive condition, space use behavior (which influences the probability of catches and recaptures in different locations) and environmental factors. Thus, the objective of this study was to evaluate the influence of such factors on the infection of Eimeria spp. (intestinal endoparasite) in Gracilinanus agilis, a semelparous didelphid neotropical marsupial. The collection site was a restricted-sense cerrado fragment at the Panga Ecological Station, MG, between 2011 to 2015. A capture-mark-recapture method was used for the hosts identification and the prevalence and abundance of the parasite were evaluated by means of laboratory fecal analyzes. The abundance and prevalence of Eimeria spp. were associated mainly with the reproductive status of the individuals, with both sexes presenting higher prevalence and high parasitic abundance during the end of the reproductive period, which coincides with the rainy season. Males had more parasites than females during the dry season, when the breeding season begins, in which mating occurs. The hypotheses wasn’t confirmed that the highest abundance on males would be due to their greater spatial displacement. However, the number of recaptures of G. agilis was significantly correlated with the abundance of Eimeria spp. This pattern can be explained by the greater contact of the marsupial with its own feces, which transmit the parasites, as well as by the increased stress caused by the entrapment, that negatively influences the immunological system efficiency. Thus, the presence and abundance of Eimeria spp. during the reproductive period in both sexes seems to be due to behavioral differences that define distinctions in susceptibility to infection rather than host exposure, once we failed to find any correlation between host mobility and Eimeria infection. However, our estimates of G. agilis use of space shoud be viewed with caution, due to the low number of recaptures which could lead to underestimates, and consequently disrupts any existing relationship between these variables.<br>Dissertação (Mestrado)